U.S. patent application number 11/536211 was filed with the patent office on 2007-02-01 for plating apparatus, plating cup and cathode ring.
This patent application is currently assigned to Dainippon Screen Mfg. Co., Ltd.. Invention is credited to Ryuichi Hayama, Hideaki Matsubara, Masahiro Miyagi, Yasuhiro Mizohata.
Application Number | 20070023277 11/536211 |
Document ID | / |
Family ID | 32588627 |
Filed Date | 2007-02-01 |
United States Patent
Application |
20070023277 |
Kind Code |
A1 |
Mizohata; Yasuhiro ; et
al. |
February 1, 2007 |
PLATING APPARATUS, PLATING CUP AND CATHODE RING
Abstract
A plating apparatus (10) provided with: a plating vessel (61a to
61d) having a cylindrical side wall (361) for containing a plating
liquid; a substrate holding mechanism (74a to 74d) for generally
horizontally holding a generally round substrate (W) to be treated;
a cathode ring (80) provided in the substrate holding mechanism and
having substantially the same inner diameter as the plating vessel
for sealing a peripheral edge portion of a lower surface of the
substrate, the cathode ring having a cathode (83) to be brought
into contact with the substrate held by the substrate holding
mechanism; and a rotative driving mechanism (45) for rotating the
substrate held by the substrate holding mechanism together with the
cathode ring; wherein the plating vessel has an upper edge portion
complementary in configuration to a portion of the cathode ring
opposed to the plating vessel so that the lower surface of the
substrate held by the substrate holding mechanism can approach the
plating vessel so as to be substantially flush with the upper edge
of the plating vessel without interference between the upper edge
portion of the plating vessel and the cathode ring.
Inventors: |
Mizohata; Yasuhiro; (Kyoto,
JP) ; Matsubara; Hideaki; (Kyoto, JP) ;
Miyagi; Masahiro; (Kyoto, JP) ; Hayama; Ryuichi;
(Kyoto, JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
US
|
Assignee: |
Dainippon Screen Mfg. Co.,
Ltd.
|
Family ID: |
32588627 |
Appl. No.: |
11/536211 |
Filed: |
September 28, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10405016 |
Mar 31, 2003 |
|
|
|
11536211 |
Sep 28, 2006 |
|
|
|
Current U.S.
Class: |
204/212 ;
257/E21.175 |
Current CPC
Class: |
H01L 21/2885 20130101;
C25D 7/123 20130101; C25D 5/04 20130101; C25D 5/08 20130101; C25D
17/005 20130101; C25D 17/12 20130101; C25D 17/06 20130101; C25D
17/001 20130101; C25D 21/08 20130101; C25D 5/003 20130101 |
Class at
Publication: |
204/212 |
International
Class: |
C25D 17/00 20060101
C25D017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 21, 2003 |
JP |
2003-012681 |
Claims
1-48. (canceled)
49. A plating apparatus for plating a substrate, the apparatus
comprising: a cassette stage for receiving thereon a cassette which
is capable of accommodating a substrate to be treated; a plating
unit comprising a cathode ring having a cathode to be brought into
contact with the substrate and rotatable together with the
substrate kept in contact with the cathode, and a plating cup
having an anode disposed therein and capable of containing a
plating liquid which contains a plating accelerating additive, a
plating retarding additive and chlorine as minor constituents
thereof; a cleaning unit for cleaning the substrate; a substrate
transport mechanism for transporting the substrate between the
cassette placed on the cassette stage, the plating unit and the
cleaning unit; a post-treatment agent supplying section for
supplying a post-treatment agent to the cleaning unit; a minor
constituent managing section comprising an analyzing section for
quantitatively analyzing the plating accelerating additive and the
plating retarding additive in the plating liquid being used in the
plating unit, and a minor constituent management controller for
controlling the minor constituent managing section, the analyzing
section comprising an analyzing cup capable of containing a part of
the plating liquid to be analyzed, a plurality of reagent supply
nozzles for supplying analytic liquid reagents into the analyzing
cup, and a rotary electrode, a counter electrode and a reference
electrode for a CVS analysis or a CPVS analysis; an enclosure which
houses therein a substrate treating section including the plating
unit, the cleaning unit and the substrate transport mechanism; and
a system controller for controlling the entire apparatus, wherein
at least one of the plural reagent supply nozzles has an opening
having an open diameter of 0.1 mm to 1 mm.
50. A plating apparatus as set forth in claim 49, wherein the
analyzing cup has a drain port provided in a bottom thereof,
wherein the bottom of the analyzing cup is inclined downward toward
the drain port.
51. A plating apparatus as set forth in claim 49, wherein the
analyzing section further comprises a deionized water nozzle for
supplying deionized water into the analyzing cup.
52. A plating apparatus as set forth in claim 49, wherein the
plating cup comprises a plating vessel having a cylindrical side
wall for containing a plating liquid; and the cathode ring has
substantially the same inner diameter as the plating vessel, the
cathode ring being for sealing a peripheral edge portion of a lower
surface of the substrate; wherein the plating unit further
comprises: a substrate holding mechanism for generally horizontally
holding a generally round substrate to be treated, the substrate
holding mechanism comprising the cathode ring; and a rotative
driving mechanism for rotating the substrate held by the substrate
holding mechanism together with the cathode ring; wherein the
plating vessel has an upper edge portion complementary in
configuration to a portion of the cathode ring opposed to the
plating vessel so that the lower surface of the substrate held by
the substrate holding mechanism can approach the plating vessel so
as to be substantially flush with an upper edge of the plating
vessel without interference between the upper edge portion of the
plating vessel and the cathode ring; wherein the cathode ring
includes a body and an abutment portion for abutting the lower
surface of the substrate, the abutment portion being composed of a
rigid material and projecting as tapered inwardly from the body of
the cathode ring; and the abutment portion has a sealing surface
for sealing the peripheral edge portion of the lower surface of the
substrate; wherein the substrate holding mechanism further
comprises a substrate back side press plate having a projection
composed of a soft material, the substrate back side press plate
opposing the abutment portion of the cathode ring; and the
substrate holding mechanism is constructed to hold a substrate by
the sealing surface of the abutment portion and the projection of
the substrate back side press plate.
53. A plating apparatus for plating a substrate, the apparatus
comprising: a cassette stage for receiving thereon a cassette which
is capable of accommodating a substrate to be treated; a plating
unit comprising a cathode ring having a cathode to be brought into
contact with the substrate and rotatable together with the
substrate kept in contact with the cathode, and a plating cup
having an anode disposed therein and capable of containing a
plating liquid which contains a plating accelerating additive, a
plating retarding additive and chlorine as minor constituents
thereof; a cleaning unit for cleaning the substrate; a substrate
transport mechanism for transporting the substrate between the
cassette placed on the cassette stage, the plating unit and the
cleaning unit; a post-treatment agent supplying section for
supplying a post-treatment agent to the cleaning unit; a minor
constituent managing section comprising an analyzing section for
quantitatively analyzing the plating accelerating additive and the
plating retarding additive in the plating liquid being used in the
plating unit, and a minor constituent management controller for
controlling the minor constituent managing section; the analyzing
section comprising an analyzing cup capable of containing a part of
the plating liquid to be analyzed, a plurality of reagent supply
nozzles for supplying analytic liquid reagents into the analyzing
cup, and a rotary electrode, a counter electrode and a reference
electrode for a CVS analysis or a CPVS analysis; an enclosure which
houses therein a substrate treating section including the plating
unit, the cleaning unit and the substrate transport mechanism; and
a system controller for controlling the entire apparatus, wherein
the analyzing section further comprises a syringe pump for
supplying the analytic reagent into the analyzing cup, wherein the
syringe pump is controlled by the minor constituent management
controller.
54. A plating apparatus as set forth in claim 53, wherein the
analyzing cup has a drain port provided in a bottom thereof,
wherein the bottom of the analyzing cup is inclined downward toward
the drain port.
55. A plating apparatus as set forth in claim 53, wherein the
analyzing section further comprises a deionized water nozzle for
supplying deionized water into the analyzing cup.
56. A plating apparatus as set forth in claim 53, wherein the
plating cup comprises a plating vessel having a cylindrical side
wall for containing a plating liquid; and the cathode ring has
substantially the same inner diameter as the plating vessel, the
cathode ring being for sealing a peripheral edge portion of a lower
surface of the substrate; wherein the plating unit further
comprises: a substrate holding mechanism for generally horizontally
holding a generally round substrate to be treated, the substrate
holding mechanism comprising the cathode ring; and a rotative
driving mechanism for rotating the substrate held by the substrate
holding mechanism together with the cathode ring; wherein the
plating vessel has an upper edge portion complementary in
configuration to a portion of the cathode ring opposed to the
plating vessel so that the lower surface of the substrate held by
the substrate holding mechanism can approach the plating vessel so
as to be substantially flush with an upper edge of the plating
vessel without interference between the upper edge portion of the
plating vessel and the cathode ring; wherein the cathode ring
includes a body and an abutment portion for abutting the lower
surface of the substrate, the abutment portion being composed of a
rigid material and projecting as tapered inwardly from the body of
the cathode ring; and the abutment portion has a sealing surface
for sealing the peripheral edge portion of the lower surface of the
substrate; wherein the substrate holding mechanism further
comprises a substrate back side press plate having a projection
composed of a soft material, the substrate back side press plate
opposing the abutment portion of the cathode ring; and the
substrate holding mechanism is constructed to hold a substrate by
the sealing surface of the abutment portion and the projection of
the substrate back side press plate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a plating apparatus for
plating a substrate such as a semiconductor wafer with copper.
[0003] 2. Description of Related Art
[0004] In the production of a semiconductor device, a plating
process is often performed for plating one surface of a
semiconductor wafer (hereinafter referred to simply as "wafer").
Plating apparatuses for the plating of the wafer are required to
perform complicated process steps and to provide a high-quality
metal film (for example, having a highly uniform thickness) by the
plating. Since the semiconductor wafer is formed with fine holes
and grooves, it is necessary to fill the fine holes and grooves
with copper by the plating.
[0005] An exemplary plating apparatus for the copper plating of the
semiconductor wafer is disclosed in U.S. Pat. No. 6,261,433 B1.
[0006] However, none of the conventional plating apparatuses are
satisfactory in the quality of a film formed by the plating,
operability, productivity and the like.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide a
plating apparatus which is capable of properly performing a plating
process.
[0008] It is another object of the present invention to provide a
plating apparatus which features easier operation.
[0009] It is further another object of the present invention to
provide a plating apparatus which features higher productivity.
[0010] It is still another object of the present invention to
provide a plating cup which ensures that a plating process can
properly be performed.
[0011] It is further another object of the present invention to
provide a cathode ring which ensures that a plating process can
properly be performed.
[0012] A plating apparatus (10) according to the present invention
comprises: a plating vessel (61a to 61d) having a cylindrical side
wall (361) for containing a plating liquid; a substrate holding
mechanism (74a to 74d) for generally horizontally holding a
generally round substrate (W) to be treated; a cathode ring (80)
provided in the substrate holding mechanism and having
substantially the same inner diameter as the plating vessel for
sealing a peripheral edge portion of a lower surface of the
substrate, the cathode ring having a cathode (83) to be brought
into contact with the substrate held by the substrate holding
mechanism; and a rotative driving mechanism (45) for rotating the
substrate held by the substrate holding mechanism together with the
cathode ring; wherein the plating vessel has an upper edge portion
complementary in configuration to a portion of the cathode ring
opposed to the plating vessel so that the lower surface of the
substrate held by the substrate holding mechanism can approach the
plating vessel so as to be substantially flush with an upper edge
of the plating vessel without interference between the upper edge
portion of the plating vessel and the cathode ring. The components
represented by the parenthesized alphanumeric characters are
equivalent to those to be described in the following embodiment.
However, it should be understood that the present invention be not
limited to the embodiment. This definition is also applied to the
following description.
[0013] With this arrangement, the plating liquid is contained in
the plating vessel, and the lower surface of the to-be-treated
substrate can be brought into contact with the plating liquid with
the substrate being generally horizontally held by the substrate
holding mechanism. The substrate may have a diameter greater than
the inner diameter of the cathode ring. In this case, the
peripheral edge portion of the lower surface of the substrate can
be sealed by the cathode ring. Since the inner diameter of the
cathode ring is virtually equal to the inner diameter of the
plating vessel, a surface area of the substrate exposed from the
cathode ring has a round shape having a diameter virtually equal to
the inner diameter of the plating vessel, and the exposed surface
area of the substrate is brought into contact with the plating
liquid in a plating process.
[0014] With the lower surface of the substrate kept in contact with
the plating liquid, an electrolytic plating process can be
performed on the lower surface of the substrate by electrically
energizing the substrate via the cathode. At this time, the
substrate can be moved relative to the plating liquid by rotating
the substrate by means of the rotative driving mechanism, whereby
the uniformity of the plating is improved.
[0015] The plating liquid may be supplied into the plating vessel,
for example, via a pipe connected to the bottom of the plating
vessel. In this case, the plating process can be performed, while
the plating liquid is continuously supplied into the plating vessel
to overflow from the upper edge of the plating vessel. Thus, the
surface of the plating liquid is kept raised slightly from the edge
of the plating vessel (e.g., by about 2.5 mm). Since the upper edge
portion of the plating vessel is complementary in configuration to
the portion (lower portion) of the cathode ring opposed to the
plating vessel, the substrate held by the substrate holding
mechanism can be brought into contact with the plating liquid
raised from the edge of the plating vessel without interference
between the upper edge portion of the plating vessel and the
cathode ring.
[0016] Further, the lower surface of the substrate held by the
substrate holding mechanism can be brought into substantially flush
relation with the upper edge of the plating vessel, so that a
distance between the lower surface of the substrate and the upper
edge of the plating vessel can be reduced (e.g., to 0.3 mm to 1.0
mm) in the plating process. In this case, the plating liquid
continuously supplied into the plating vessel flows in the form of
a laminar flow along the lower surface of the substrate to the
peripheral edge of the substrate in the vicinity of the lower
surface of the substrate, and then flows out of the plating vessel
through a gap defined between the upper edge of the plating vessel
and the lower surface of the substrate.
[0017] Even if air bubbles are trapped between the substrate and
the plating liquid, the air bubbles flow together with the plating
liquid out of the plating vessel. The laminar flow of the plating
liquid flowing along the lower surface of the substrate to the
peripheral edge of the substrate and the absence of the air bubbles
on the lower surface of the substrate make it possible to form a
uniform film by the plating. That is, this plating apparatus can
advantageously perform the plating process.
[0018] The inventive plating apparatus may further comprise a first
adjustment mechanism (230, 231, 233, 235, 238A, 238B) for generally
aligning the center axis of the plating vessel with the rotation
axis of the cathode ring.
[0019] With this arrangement, the center axis of the plating vessel
can virtually be aligned with the rotation axis of the cathode ring
by the first adjustment mechanism. Where the rotation axis and
center axis of the cathode ring coincide with each other, the
interference between the plating vessel and the cathode ring can be
prevented even if the cathode ring is slightly spaced from the
upper edge of the plating vessel. This state is maintained even
when the substrate is rotated by the rotative driving
mechanism.
[0020] In the inventive plating apparatus, the upper edge of the
plating vessel is present within substantially the same plane. The
apparatus may further comprise a second adjustment mechanism (238A,
238B) for positioning the upper edge of the plating vessel within a
generally horizontal plane.
[0021] With this arrangement, the upper edge of the plating vessel
can be positioned within the generally horizontal plane by the
second adjustment mechanism. Therefore, the substrate generally
horizontally held by the substrate holding mechanism can be spaced
a substantially constant distance from the upper edge of the
plating vessel in adjacent relation. Thus, the substrate can
circumferentially be spaced a sufficiently small distance from the
upper edge of the plating vessel in non-contact adjacent
relation.
[0022] With the upper edge of the plating vessel positioned within
the generally horizontal plane, the plating liquid continuously
supplied into the plating vessel from the pipe connected to the
bottom of the plating vessel overflows circumferentially uniformly
from the upper edge of the plating vessel. Thus, the exposed area
of the lower surface of the substrate can entirely be brought into
contact with the plating liquid.
[0023] The inventive plating apparatus may further comprise a
retracting mechanism (222a, 44a) having a pivot shaft (223)
generally horizontally disposed at a lower height than the bottom
of the plating vessel and coupled to the substrate holding
mechanism, the retracting mechanism (222a, 44a) being capable of
pivoting the substrate holding mechanism about the pivot shaft to
move the substrate holding mechanism between an upper position
above the plating vessel and a retracted position apart from the
upper position.
[0024] With this arrangement, the substrate holding mechanism can
be located at the upper position above the plating vessel in the
plating process, and retracted from the upper position to the
retracted position in maintenance of the apparatus by the
retracting mechanism.
[0025] The inventive plating apparatus may further comprise a
cathode cleaning liquid supplying mechanism (81) for supplying a
cathode cleaning liquid to the cathode of the cathode ring for
cleaning the cathode in the plating process.
[0026] The cathode is generally prevented from contacting the
plating liquid when the peripheral edge portion of the substrate
kept in contact with the cathode is sealed by the cathode ring.
Where the sealing by the cathode ring is insufficient, however, the
plating liquid is likely to reach the cathode. Further, even if the
sealing by the cathode ring is proper, the plating liquid remaining
on the exposed surface of the substrate is likely to be sucked into
the gap between the substrate and the cathode ring to contact the
cathode when the cathode ring is disengaged from the substrate
after the completion of the plating process.
[0027] With the aforesaid arrangement, the cathode cleaning liquid
can be supplied to the cathode by the cathode cleaning liquid
supplying mechanism to rinse away the plating liquid adhering on
the cathode. Thus, the cathode can be kept clean to properly
electrically energize the substrate for the electrolytic
plating.
[0028] Another plating apparatus (10) according to the present
invention comprises: a plating vessel (61a to 61d) for containing a
plating liquid for performing a plating process on a substrate (W)
to be treated; a substrate holding mechanism (74a to 74d) to be
disposed above the plating vessel for generally horizontally
holding the substrate to bring the substrate into contact with the
plating liquid contained in the plating vessel; and a retracting
mechanism (222a, 44a) having a pivot shaft (223) generally
horizontally disposed at a lower height than the bottom of the
plating vessel and coupled to the substrate holding mechanism, the
retracting mechanism being capable of pivoting the substrate
holding mechanism about the pivot shaft to move the substrate
holding mechanism between an upper position above the plating
vessel and a retracted position apart from the upper position.
[0029] According to the present invention, the substrate held by
the substrate holding mechanism can be brought into contact with
the plating liquid contained in the plating vessel for the plating
thereof. Further, the substrate holding mechanism can be located at
the upper position above the plating vessel in the plating process,
and retracted from the upper position to the retracted position in
maintenance of the apparatus by the retracting mechanism.
[0030] In the inventive plating apparatus, the plating vessel may
have a cylindrical side wall (361), and the substrate holding
mechanism may include a cathode ring (80) having substantially the
same inner diameter as the plating vessel for sealing a peripheral
edge portion of a lower surface of the to-be-treated substrate, the
cathode ring being rotatable about a rotation axis thereof, the
cathode ring including a cathode (83) to be brought into contact
with the substrate held by the substrate holding mechanism. The
plating apparatus may further comprise a first adjustment mechanism
(230, 231, 233, 235, 238A, 238B) for aligning the center axis of
the plating vessel with the rotation axis of the cathode ring.
[0031] With this arrangement, the peripheral edge portion of the
lower surface of the substrate held by the substrate holding
mechanism is covered with the cathode ring, and an inward round
area of the lower surface of the substrate is exposed from the
cathode ring. With the exposed area of the lower surface of the
substrate kept in contact with the plating liquid contained in the
plating vessel, the substrate is electrically energized by the
cathode of the cathode ring for electrolytic plating.
[0032] Where the rotation axis and center axis of the cathode ring
coincide with each other, the plating vessel and the cathode ring
can be kept in circumferentially adjacent relation without
interference therebetween by aligning the center axis of the
plating vessel with the rotation axis of the cathode ring by the
first adjustment mechanism.
[0033] In the inventive plating apparatus, the plating vessel has
an upper edge present within substantially the same plane. The
apparatus may further comprise a second adjustment mechanism (238A,
238B) for positioning the upper edge of the plating vessel within a
generally horizontal plane.
[0034] With this arrangement, the upper edge of the plating vessel
can be positioned within the generally horizontal plane by the
second adjustment mechanism. Therefore, the substrate generally
horizontally held by the substrate holding mechanism can be brought
into non-contact adjacent relation to the upper edge of the plating
vessel, whereby the surface area of the substrate exposed from the
cathode ring can be brought into contact with the plating liquid
contained (filled) in the plating vessel.
[0035] In the inventive plating apparatus, the plating vessel may
have a cylindrical side wall (361), and the substrate holding
mechanism may include a cathode ring (80) having substantially the
same inner diameter as the plating vessel for sealing a peripheral
edge portion of a lower surface of the to-be-treated substrate, the
cathode ring being rotatable about a rotation axis thereof, the
cathode ring including a cathode (83) to be brought into contact
with the to-be-treated substrate. The apparatus may further
comprise a cathode cleaning liquid supplying mechanism (81) for
supplying a cathode cleaning liquid to the cathode for cleaning the
cathode in the plating process.
[0036] With this arrangement, the electrolytic plating process can
be performed on the substrate by electrically energizing the
substrate by the cathode. The cathode ring generally prevents the
cathode from contacting the plating liquid in the plating process.
However, if the plating liquid happens to reach the cathode for
some reason, the cathode can be cleaned by the cathode cleaning
liquid supplying mechanism. Thus, the cathode can be kept clean,
and properly brought into contact with the substrate for the
electrolytic plating.
[0037] Further another plating apparatus (10) according to the
present invention comprises: a plating vessel (61a to 61d) for
containing a plating liquid; an anode (76) disposed in the plating
vessel; a mesh member (49) of a resin disposed at a higher height
than the anode in the plating vessel; and a substrate holding
mechanism (74a to 74d) for holding a to-be-treated substrate (W) so
as to locate the substrate at a plating position in contact with
the plating liquid filled in the plating vessel, wherein a distance
between the substrate located at the plating position and the mesh
member is 0.5 mm to 30 mm.
[0038] According to the present invention, an electrolytic plating
process can be performed on the substrate kept in contact with the
plating liquid by electrically energizing the plating liquid
through the anode. At this time, the mesh-member is present between
the anode and the substrate. Since the mesh member is composed of
the resin, the electrical resistance of the plating liquid in a
region between the anode and the substrate in the plating vessel is
increased due to the presence of the mesh member.
[0039] The plating apparatus may further comprise a cathode to be
brought into contact with a peripheral edge portion of the
substrate. In an electrical conduction path extending from the
anode through the plating liquid to the cathode kept in contact
with the peripheral edge portion of the substrate, a path passing
through the center of the substrate has substantially the same
electrical resistance as a path passing through the peripheral edge
port ion of the substrate but not through the center of the
substrate. This is because the electrical resistance of the plating
liquid contained in the plating vessel is increased by the mesh
member and, hence, the electrical resistance between the center of
the substrate and the peripheral edge portion of the substrate
(cathode) is much smaller than the electrical resistance of the
path extending from the anode to the substrate.
[0040] A film growth rate in the plating process is virtually
proportional to the amperage of the electric current flowing across
the interface between the substrate and the plating liquid. Where
the path passing through the center of the substrate has
substantially the same electrical resistance as the path passing
through the peripheral edge portion of the substrate but not
through the center of the substrate as described above, the
electric current generally uniformly flows between the plating
liquid and the substrate at different points on the substrate.
Thus, the film growth rate in the plating process is generally
uniform over the substrate. Therefore, the film formed by the
plating has a generally uniform thickness.
[0041] The mesh member preferably covers almost the entire plating
vessel as viewed in plan. Thus, the plating liquid in the plating
vessel has a uniform electrical resistance as measured vertically
at different points within a horizontal plane.
[0042] Where the plating liquid is supplied into the plating vessel
through a pipe connected to the bottom of the plating vessel, the
plating liquid flows upward from a lower side in the plating
vessel. At this time, contaminants in the plating liquid can be
removed by the mesh member. The plating liquid flowing upward from
the lower side is rectified into a generally uniform upward flow by
the mesh member.
[0043] The plating apparatus may further comprise a rotative
driving mechanism for rotating the substrate held by the substrate
holding mechanism. Since the substrate located at the plating
position and the mesh member are spaced only 0.5 mm to 30 mm from
each other in adjacent relation, the plating liquid is drawn by the
substrate in a limited region when the substrate is rotated in
contact with the plating liquid. This suppresses the eddy flow of
the plating liquid which is unwanted for the plating. Thus, the
film formed by the plating has a uniform thickness.
[0044] The distance between the substrate located at the plating
position and the mesh member is preferably 0.5 mm to 20 mm.
[0045] The mesh member may include a plurality of mesh members
which are vertically stacked one on another. The stacked mesh
members have an increased total thickness as measured vertically.
This enhances the effect of increasing the electrical resistance
between the anode and the substrate, the effect of removing the
contaminants and the effect of rectifying the plating liquid. The
plating liquid flows in the form of a laminar flow along the lower
surface of the substrate to the peripheral edge of the substrate in
the vicinity of the lower surface of the substrate.
[0046] A plating cup (56a to 56d) according to the present
invention comprises: a plating vessel (61a to 61d) for containing a
plating liquid; a shower head (75) for diffusively introducing the
plating liquid into the plating vessel from a plating liquid
introduction port (54) provided in the bottom of the plating
vessel; a mesh anode (76) disposed at a higher height than the
shower head in the plating vessel; and a mesh member (49) of a
resin disposed at a higher height than the anode in the plating
vessel.
[0047] According to the present invention, the plating liquid can
diffusively be introduced in various directions (at various angles)
into the plating vessel by the shower head. Since the plating
liquid is introduced into the plating vessel from the plating
liquid introduction port provided in the bottom of the plating
vessel, the plating liquid flows upward from a lower side in the
form of an upward flow in the plating vessel. Since the anode is of
a mesh shaped, the plating liquid can pass upwardly through the
anode.
[0048] The plating liquid flows further upward to pass upwardly
through the mesh member disposed at a height higher than the anode.
At this time, the plating liquid is rectified into a uniform upward
flow.
[0049] With the use of the plating cup, a plating process can be
performed on a to-be-treated substrate, while the plating liquid is
introduced from the plating liquid introduction port to overflow
from the upper edge of the plating vessel with the substrate kept
in contact with the surface of the plating liquid. Since the
plating liquid is supplied in the form of a uniform upward flow to
the surface of the substrate, the substrate can uniformly be
plated.
[0050] Contaminants in the plating liquid can be removed by the
mesh member. Thanks to the aforesaid effects, the plating process
can advantageously be performed with the use of the plating
cup.
[0051] In the inventive plating cup, the mesh member may include a
plurality of mesh members which are stacked one on another.
[0052] The stacked mesh members have an increased total thickness
as measured vertically. This enhances the plating liquid rectifying
effect and the contaminant removing effect.
[0053] Still another plating apparatus (10) according to the
present invention comprises: a cathode (83) to be brought into
contact with a substrate (W) to be treated; and a cathode cleaning
liquid supplying mechanism (81) for supplying a cathode cleaning
liquid to the cathode for cleaning the cathode.
[0054] According to the present invention, an electrolytic plating
process can be performed on the substrate by electrically
energizing the substrate by the cathode. If the cathode is
contaminated with the plating liquid, the cathode can be cleaned by
the cathode cleaning liquid supplying mechanism. Thus, the cathode
can be kept clean, so that the electrolytic plating process can be
performed with the cathode properly kept in contact with the
substrate.
[0055] The inventive plating apparatus may further comprise a
conductivity meter (212) disposed downstream of the cathode in a
flow channel of the cathode cleaning liquid supplied by the cathode
cleaning liquid supplying mechanism for measuring the electrical
conductivity of the cathode cleaning liquid.
[0056] With this arrangement, the electrical conductivity of the
cathode cleaning liquid flowing in the vicinity of the cathode can
be measured by the conductivity meter, which is disposed downstream
of the cathode in the cathode cleaning liquid flow channel.
[0057] The plating apparatus may generally be constructed so as not
to permit the plating liquid to intrude into the cathode cleaning
liquid flow channel. The plating process can be performed by
supplying the cathode cleaning liquid to the cathode while
measuring the electrical conductivity of the cathode cleaning
liquid flowing in the vicinity of the cathode by means of the
conductivity meter. The cathode cleaning liquid and the plating
liquid differ in electrical conductivity. Therefore, if the plating
liquid is mixed in the cathode cleaning liquid, the electrical
conductivity of the cathode cleaning liquid measured by the
conductivity meter is changed. This makes it possible to detect the
intrusion of the plating liquid into the cathode cleaning liquid
flow channel, thereby avoiding such an event that the plating
process is continuously performed with the cathode left
contaminated with the plating liquid.
[0058] The cathode cleaning liquid may be, for example, deionized
water. In this case, the electrical conductivity measured by the
conductivity meter is drastically increased by even a very small
amount of the plating liquid mixed in the cathode cleaning
liquid.
[0059] The inventive plating apparatus may further comprise a
cathode cleaning liquid collection vessel (210) for collecting the
cathode cleaning liquid supplied by the cathode cleaning liquid
supplying mechanism.
[0060] With this arrangement, the cathode cleaning liquid can be
collected separately from the plating liquid used in the plating
vessel by providing the cathode cleaning liquid collection vessel
dedicated to the collection of the cathode cleaning liquid.
[0061] Further another plating apparatus (10) according to the
present invention is adapted to perform a plating process on a
to-be-treated substrate (W) with the use of a plating liquid, and
comprises: a liquid supplying mechanism (81) for supplying liquid
to a restriction region (80f) where intrusion of the plating liquid
is prevented in the plating apparatus, the restriction region
having a liquid inlet and a liquid outlet; and a conductivity meter
(212) for measuring the electrical conductivity of the liquid
flowing out of the outlet of the restriction region.
[0062] The plating liquid may usually be prevented from intruding
into the restriction region. According to the present invention, if
the plating liquid happens to intrude into the restriction region
for some reason, the plating liquid flows together with the liquid
supplied by the liquid supplying mechanism to reach the
conductivity meter. Where the liquid supplied by the liquid
supplying mechanism and the plating liquid differ in electrical
conductivity, the intrusion of the plating liquid into the
restriction region where the intrusion of the plating liquid is
usually prevented can be detected on the basis of the electrical
conductivity measured by the conductivity meter.
[0063] The restriction region may be the inside of a through-hole
or a planar region having a surface on which the liquid flows.
[0064] In the inventive plating apparatus, the liquid supplying
mechanism may be capable of supplying the liquid in the plating
process.
[0065] With this arrangement, the intrusion of the plating liquid
into the restriction region can be detected in the plating process.
If the plating process cannot properly be performed when the
plating liquid intrudes into the restriction region, the plating
process can be interrupted.
[0066] The inventive plating apparatus may further comprise a
liquid collection vessel (210) for collecting the liquid supplied
by the liquid supplying mechanism.
[0067] With this arrangement, the liquid can be collected
separately from the plating liquid by providing the liquid
collection vessel dedicated to the collection of the liquid
supplied by the liquid supplying mechanism.
[0068] Still another plating apparatus (10) according to the
present invention comprises: a plating vessel (61a to 61d) for
containing a plating liquid for performing a plating process on a
substrate (W) to be treated; a cathode (83) to be brought into
contact with the substrate in the plating process; a recovery
vessel (62a to 62d) disposed around the plating vessel for
recovering the plating liquid overflowing from the plating vessel;
and a cathode cleaning liquid collection vessel (210) disposed
around the recovery vessel for collecting a cathode cleaning liquid
for cleaning the cathode.
[0069] According to the present invention, the plating process can
be performed, while the plating liquid is supplied into the plating
vessel to overflow from the plating vessel into the recovery vessel
with the to-be-treated substrate kept in contact with the surface
of the plating liquid filled in the plating vessel. In this case,
the plating liquid is raised from the upper edge of the plating
vessel, so that the to-be-treated substrate can easily be brought
into contact with the surface of the plating liquid. An
electrolytic plating process can be performed by electrically
energizing the substrate with the substrate kept in contact with
the cathode.
[0070] The cathode cleaning liquid used for the cleaning of the
cathode can be collected separately from the plating liquid used in
the plating vessel by the cathode cleaning liquid collection vessel
provided separately from the recovery vessel. Thus, the cathode
cleaning liquid can be prevented from being mixed in the plating
liquid, so that the plating liquid is suitable for reuse. In this
case, the plating process can be performed on the substrate, for
example, while the plating liquid is circulated through the plating
vessel and the recovery vessel.
[0071] The inventive plating apparatus may further comprise a
conductivity meter (212) disposed downstream of the cathode in a
flow channel of the cathode cleaning liquid used for the cleaning
of the cathode for measuring the electrical conductivity of the
cathode cleaning liquid.
[0072] With this arrangement, the electrical conductivity of the
cathode cleaning liquid flowing in the vicinity of the cathode can
be measured by the conductivity meter, which is disposed downstream
of the cathode in the cathode cleaning liquid flow channel.
[0073] The plating apparatus may generally be constructed so as not
to permit the plating liquid to intrude into the cathode cleaning
liquid flow channel. Since the cathode is disposed in the cathode
cleaning liquid flow channel, the plating liquid is usually kept
out of contact with the cathode.
[0074] The plating process can be performed by supplying the
cathode cleaning liquid to the cathode while measuring the
electrical conductivity of the cathode cleaning liquid flowing in
the vicinity of the cathode by means of the conductivity meter. The
cathode cleaning liquid and the plating liquid differ in electrical
conductivity. Therefore, if the plating liquid is mixed in the
cathode cleaning liquid, the electrical conductivity of the cathode
cleaning liquid measured by the conductivity meter is changed. This
makes it possible to detect the intrusion of the plating liquid
into the cathode cleaning liquid flow channel, thereby avoiding
such an event that the plating process is continuously performed
with the cathode left contaminated with the plating liquid.
[0075] The inventive plating apparatus may further comprise a
cathode cleaning liquid supplying mechanism (81) for supplying the
cathode cleaning liquid to the cathode for the cleaning of the
cathode.
[0076] With this arrangement, the cathode cleaning liquid can
automatically be supplied to the cathode by the cathode cleaning
liquid supplying mechanism. This facilitates the operation of the
plating apparatus.
[0077] Further another plating apparatus according to the present
invention comprises: an anode (76) for electrically energizing a
plating liquid; a cathode (83) for electrically energizing a
substrate (W) to be treated; and a plating power source (82) for
applying a voltage between the anode and the cathode; wherein an
electrical conduction path between the anode and the plating power
source and an electrical conduction path between the cathode and
the plating power source are isolated from the ground.
[0078] According to the present invention, an electrolytic plating
process can be performed on the to-be-treated substrate by applying
the voltage between the anode and the cathode by the plating power
source with the anode and the cathode kept in contact with the
plating liquid and the substrate, respectively, and with the
substrate kept in contact with the plating liquid. Thus, a target
metal contained in the form of cations (e.g., copper ions) in the
plating liquid can be deposited on the substrate.
[0079] Since the electrical conduction path between the anode and
the plating power source and the electrical conduction path between
the cathode and the plating power source are not connected to the
ground, an electric current is prevented from flowing through
unintended portions in the plating apparatus, and a noise is
prevented from interfering with electric currents flowing between
the anode and the plating power source and between the cathode and
the plating power source.
[0080] The inventive plating apparatus may further comprise: a
substrate holding mechanism (74a to 74d) for holding the
to-be-treated substrate (W), the substrate holding mechanism
including a rotary shaft (77); a rotative driving mechanism (45)
for rotating the substrate held by the substrate holding mechanism
about the rotary shaft; and an electrical conduction line (198)
provided in the rotary shaft and rotatable together with the rotary
shaft by a rotation force of the rotative driving mechanism, the
electrical conduction line being electrically connected to the
cathode and electrically isolated from the rotary shaft; wherein
the cathode is provided in the substrate holding mechanism and
adapted to be brought into contact with the substrate held by the
substrate holding mechanism.
[0081] With this arrangement, the substrate can be moved relative
to the plating liquid by rotating the substrate by the rotative
driving mechanism while keeping the substrate held by the substrate
holding mechanism in contact with the plating liquid. Thus, the
substrate can uniformly be plated.
[0082] The rotary shaft may be composed of an electrically
conductive material such as a metal. Since the electrical
conduction line is electrically isolated from the rotary shaft, an
electric current flowing through the electrical conduction line
does not flow through the rotary shaft and other electrically
conductive members contacting the rotary shaft even if the rotary
shaft is electrically conductive. Further, no noise interferes with
the electric current flowing through the electrical conduction line
via the rotary shaft. Therefore, a predetermined amperage of
electric current is allowed to flow through the to-be-treated
substrate via the cathode.
[0083] The inventive plating apparatus may further comprise: a
cathode ring (80) provided with the cathode and adapted to be
brought into contact with a peripheral edge portion of the
to-be-treated substrate; a spin base (78) which supports the
cathode ring; and an insulative member (78i) provided between the
cathode ring and the spin base.
[0084] With this arrangement, the electrical conduction path
between the cathode and the plating power source can be isolated
from the spin base by the insulative member even if the spin base
is composed of an electrically conductive member such as a metal.
Therefore, the electric current flowing through the electrical
conduction path between the cathode and the plating power source
does not flow through the spin base and other electrically
conductive members contacting the spin base. Further, no noise
interferes with the electric current flowing through the electrical
conduction line between the cathode and the plating power source
via the spin base. Therefore, a predetermined amperage of electric
current is allowed to flow through the to-be-treated substrate via
the cathode.
[0085] The inventive plating apparatus may further comprise a
rotary connector (197) for electrically connecting the cathode and
the plating power source via a liquid metal.
[0086] With this arrangement, the electrical connection between the
plating power source on the side of a stationary system and the
cathode can be maintained by the rotary connector, even if the
cathode is rotated together with the substrate holding
mechanism.
[0087] The liquid metal may be, for example, mercury (Hg).
[0088] Still another plating apparatus (10) according to the
present invention comprises a substrate holding mechanism (74a to
74d) for holding a substrate (W) to be treated; a cathode (83) to
be brought into contact with the substrate held by the substrate
holding mechanism; a first rotary shaft (77) having a first
electrical conduction line (198) electrically connected to the
cathode, and coupled to the substrate holding mechanism; a rotative
driving mechanism (45) for rotating the substrate held by the
substrate holding mechanism about the first rotary shaft; a second
rotary shaft (194) having a second electrical conduction line
(194); a rotation force transmission mechanism (193, 195, 196) for
transmitting a rotative driving force between the first rotary
shaft and the second rotary shaft and establishing an electrical
conduction path between the first and second electrical conduction
lines; and a rotary connector (197) attached to one end of the
second rotary shaft and electrically connected to the second
electrical conduction line.
[0089] According to the present invention, an electrical conduction
path is established as extending from the rotary connector to the
cathode through the second electrical conduction line, the rotation
force transmission mechanism and the first electrical conduction
line. Thus, an electrical conduction path can be established
between the plating power source connected to the rotary connector
on the side of a stationary system and the cathode.
[0090] The rotation speed of the second rotary shaft can be reduced
as compared with the rotation speed of the first rotary shaft by
the rotation force transmission mechanism. Thus, the rotary
connector can be rotated at a lower rotation speed for reduction of
a load exerted on the rotary connector, whereby the service life of
the rotary connector can be extended. The rotative driving
mechanism may be coupled to the first rotary shaft or to the second
rotary shaft.
[0091] The rotary connector may be of a slidable type (e.g., a slip
ring), but is preferably of a non-slidable type. Where the rotary
connector is of a non-slidable type, a noise is less likely to
interfere with an electric current flowing between the plating
power source connected to the rotary connector on the side of the
stationary system and the cathode.
[0092] The rotation force transmission mechanism may comprise: a
first pulley attached to the first rotary shaft and at least partly
electrically conductive; a second pulley attached to the second
rotary shaft and at least partly electrically conductive; and a
belt stretched between the first and second pulleys and at least
partly electrically conductive.
[0093] Further another plating apparatus (10) according to the
present invention comprises: a treatment fluid supplying member
(203, 81b) having a fluid channel (81c) formed therein for
supplying a treatment fluid to a substrate (W) to be treated; and a
rotary joint (191) being disposed in the treatment fluid supplying
member, and including a rotor (244), a stator (243) and a sliding
portion defined between the rotor and the stator, the rotary joint
having a main channel (270) to constitute a part of the fluid
channel and a leak channel (271) branched from the main channel,
the sliding portion being disposed in the leak channel.
[0094] According to the present invention, the treatment fluid can
be supplied to the to-be-treated substrate from a treatment fluid
supply source located on the side of a stationary system via the
rotary joint even if the to-be-treated substrate is rotated
together with a part of the treatment fluid supplying member. Since
the main channel of the rotary joint constitutes a part of the
fluid channel, the treatment fluid flows through the main
channel.
[0095] At this time, the internal pressure of the leak channel is
reduced as compared with the internal pressure of the main channel,
whereby a part of the treatment fluid flowing through the main
channel flows into the leak channel. Since the sliding portion is
disposed in the leak channel, particles generated around the
sliding portion are expelled out of the rotary joint via the leak
channel. Thus, the particles generated around the sliding portion
are prevented from being supplied to the to-be-treated
substrate.
[0096] The inventive plating apparatus may further comprise a
substrate holding mechanism (74a to 74d) having a support shaft
(81b) to be disposed generally vertically for holding the
to-be-treated substrate, wherein the fluid channel is provided in
the support shaft and the rotary joint is attached to one end of
the support shaft.
[0097] With this arrangement, the to-be-treated substrate held by
the substrate holding mechanism can be rotated by rotating the
substrate holding mechanism about the support shaft disposed
generally vertically. At this time, the treatment fluid can be
supplied from the treatment liquid supply source located on the
side of the stationary system to the fluid channel provided in the
support shaft via the rotary joint attached to the one end (upper
end) of the support shaft.
[0098] A cathode ring (80) according to the present invention has a
cathode (83) to be brought into contact with a peripheral edge
portion of a substrate (W) to be treated, and comprises: a first
electrically conductive member (80c) provided in the cathode ring
for electrically connecting to a plating power source (82); a
second electrically conductive member (80d) provided in the cathode
ring and electrically connected to the cathode; and a third
electrically conductive member (80e) provided between the first
electrically conductive member and the second electrically
conductive member, the third electrically conductive member being
resilient and kept in resilient contact with the first and second
electrically conductive members for electrical connection between
the first electrically conductive member and the second
electrically conductive member.
[0099] According to the present invention, the electrical
connection between the first electrically conductive member and the
second electrically conductive member can be maintained by keeping
the third electrically conductive member in resilient contact with
the first and second electrically conductive members, even if the
cathode ring is warped. Thus, an electric current is allowed to
flow between the plating power source and the cathode. Therefore,
the plating process can properly be performed on the substrate with
the use of the cathode ring.
[0100] The third electrically conductive member may be, for
example, a coil spring.
[0101] Another cathode ring (80) according to the present invention
comprises: a ring-shaped support member (80b, 80u); a cathode (83)
provided in the support member and adapted to be brought into
contact with a peripheral edge portion of a substrate (W) to be
treated; an electrically conductive member (80d, 80e, 80c) provided
in the support member and establishing an electrical conduction
path between the cathode and a plating power source (82); and a
seal member (80r) provided between the support member and the
electrically conductive member for providing a seal between the
support member and the electrically conductive member for
prevention of intrusion of a plating liquid into the support
member.
[0102] According to the present invention, the electrical
conduction path is established as extending from the plating power
source to the cathode through the electrically conductive member.
Thus, an electrolytic plating process can be performed on the
substrate by electrically energizing the substrate in contact with
the cathode by the plating power source.
[0103] Further, the seal member prevents the intrusion of the
plating liquid into the support member to keep the inside of the
support member clean.
[0104] Further another cathode ring (80) according to the present
invention comprises: a cathode (83) to be brought into contact with
a peripheral edge portion of a substrate (W) to be treated; and a
positioning member (78j, 79j) for fixing the cathode ring in a
predetermined position with respect to a spin base (78) which is
adapted to rotate while supporting the cathode ring.
[0105] According to the present invention, the cathode ring can
easily be fixed in the predetermined position with respect to the
spin base by the positioning member. The predetermined position
herein means a position at which the center axis of the cathode
ring generally coincides with the rotation axis of the spin base.
Thus, the cathode ring can properly be rotated together with the
spin base.
[0106] Still another cathode ring (80) according to the present
invention comprises: a cathode (83) to be brought into contact with
a peripheral edge portion of a substrate (W) to be treated; and an
abutment portion (80a) for holding the substrate in abutment
against the substrate, the abutment portion being composed of a
rigid material and having a sealing surface (80s) for sealing the
peripheral edge portion of the substrate.
[0107] According to the present invention, an area of the substrate
to be brought into contact with a plating liquid can be limited by
sealing the peripheral edge portion of the substrate by the sealing
surface.
[0108] Since the abutment portion is composed of the rigid
material, the size of the abutment portion and its periphery can be
reduced. That is, where the abutment portion is not composed of the
rigid material, an abutment portion supporting member should be
provided separately from the abutment portion as extending from a
side opposite from the substrate, so that the size of the abutment
portion and its periphery is increased thereby to reduce the area
of the substrate to be brought into contact with the plating
liquid. Further, when the substrate abutting against the abutment
portion is kept in contact with the plating liquid which is filled
in a plating vessel and overflows from the edge of the plating
vessel, the plating liquid is liable to be stagnated by the
abutment portion supporting member, leading to a problem of
deterioration in the uniformity of the plating.
[0109] According to the present invention, there is no need to
provide the abutment portion supporting member separately from the
abutment portion, making it possible to overcome the aforesaid
problem.
[0110] Examples of the rigid material include rigid vinyl chloride
resins, rigid fluororesins and polyimide resins. The sealing
surface is preferably a polished surface. Thus, the sealing surface
can be brought into more intimate contact with the to-be-treated
surface of the substrate.
[0111] Still another plating apparatus (10) according to the
present invention is adapted to perform a plating process on a
to-be-treated surface of a generally round semiconductor wafer (W)
having a plurality of fine holes or grooves formed in the surface
thereof and a barrier layer and a seed layer sequentially provided
on the surface as covering the holes or grooves, and comprises: a
cassette stage (16) for receiving thereon a cassette (C) capable of
accommodating the semiconductor wafer to be treated, the cassette
stage including a cassette guide (51) for limiting a cassette
loading position on the cassette stage and a cassette detection
sensor (52) for detecting the presence or absence of the cassette
at a predetermined position on the cassette stage; a plurality of
plating units (20a to 20d) each including a cathode ring (80)
having a cathode (83) to be brought into contact with the
semiconductor wafer and rotatable together with the semiconductor
wafer kept in contact with the cathode, and a plating vessel (61a
to 61d) capable of containing a plating liquid and having an anode
(76) disposed therein; a plurality of cleaning units (22a, 22b)
each including a cup (101) having a drain port (105a) and adapted
to clean the semiconductor wafer therein, a wafer holding member
(102) for holding the semiconductor wafer in the cup, a wafer
rotating mechanism (103) for rotating the semiconductor wafer held
by the wafer holding member, and a cleaning liquid supply nozzle
(102d, 107) for supplying a cleaning liquid including a
post-treatment agent to the surface of the semiconductor wafer held
by the wafer holding member, the cup being connected to an air
exhaustion mechanism for exhausting air from the cup; a wafer
transport mechanism (TR) for transporting the semiconductor wafer
subjected to the plating process in any of the plating units to any
of the cleaning units, the wafer transport mechanism including an
extendible arm (41, 42) capable of generally horizontally holding
the semiconductor wafer, a vertical movement mechanism (24) for
moving up and down the arm, and a horizontal rotating mechanism
(25) for rotating the semiconductor wafer held by the arm within a
generally horizontal plane; a post-treatment agent supplying
section (4) including a post-treatment agent tank (290) which
contains the post-treatment agent to be used in the cleaning units,
a tank enclosure (291) which houses therein the post-treatment
agent tank, and a vat (292) for receiving therein the
post-treatment agent which leaks out of the post-treatment agent
tank, the tank enclosure being connected to an air outlet pipe
(297) for exhausting air from the tank enclosure; a minor
constituent analyzing section (3) including an analyzing cup (336)
for containing the plating liquid for analyzing a specific minor
constituent of the plating liquid to be used in the plating units,
and a rotary platinum electrode (308) disposed in the analyzing
cup; an enclosure (30) which houses therein a wafer treating
section (12) including the plating units, the cleaning units and
the wafer transport mechanism, the enclosure including a barrier
wall for isolating the inside thereof from an external environment,
a frame (37) which supports the wafer treating section, and a
filter (31) provided in an upper portion thereof, the enclosure
having a loading/unloading port (Wh) for loading and unloading the
semiconductor wafer or the cassette capable of accommodating the
semiconductor wafer, a deionized water pipe introduction port (32h)
through which a deionized water pipe (32) is introduced into the
enclosure, a compressed air pipe introduction port (33h) through
which a compressed air pipe (33) is introduced into the enclosure,
an air outlet opening provided in the bottom of the enclosure for
exhausting air from the enclosure, and an air outlet pipe
connection port (34h, 35h) connected to an air outlet pipe (34, 35)
for exhausting air from the enclosure, the enclosure being
constructed so that air introduced into the enclosure through the
filter is exhausted from the enclosure through the air outlet
opening and the air outlet pipe connected to the air outlet pipe
connection port; and a system controller (155) for controlling the
entire plating apparatus, the system controller including a
plurality of printed circuit boards (155P), a central processing
unit (155C), a storage device (155M) having a semiconductor storage
medium and a magnetic storage medium and storing therein a plating
apparatus control program at least partly described in a high-level
language, a serial port (280, 281), a keyboard (157) having
alphabet inputting keys and numeral inputting keys, and a display
(156).
[0112] According to the present invention, the plating process and
the cleaning process can be performed by the plating units and the
cleaning units, respectively, in the single plating apparatus.
[0113] The cassette placed on the cassette stage can accommodate an
untreated semiconductor wafer (hereinafter referred to simply as
"wafer") as well as a wafer subjected to the plating process and
the cleaning process.
[0114] The cassette can easily be placed in the predetermined
position on the cassette stage by the cassette guide. Thus, the arm
of the wafer transport mechanism can access the cassette placed on
the cassette stage on the basis of cassette position information
preliminarily stored in the storage device of the system controller
for loading/unloading of the wafer. Since the presence or absence
of the cassette on the cassette stage can be detected by the
cassette detection sensor, it is possible to avoid such an event
that the arm of the wafer transport mechanism accesses the cassette
stage on the assumption that the cassette is placed on the cassette
stage on which actually no cassette is placed.
[0115] In the plating unit, the wafer kept in contact with the
cathode is brought into contact with the plating liquid contained
in the plating cup, and the cathode and the anode are electrically
energized, whereby a metal film (e.g., a copper film) can be formed
on the wafer by electrolytic plating.
[0116] In the cleaning unit, contaminants adhering on the surface
of the wafer can be removed, for example, by the post-treatment
agent for cleaning the wafer. At this time, the wafer can uniformly
be cleaned by supplying the cleaning liquid toward the wafer from
the cleaning liquid supply nozzle while rotating the wafer held by
the wafer holding member by means of the wafer rotating mechanism.
Mist of the cleaning liquid and the like generated during the
cleaning of the wafer can be expelled out of the plating apparatus
by the air exhaustion mechanism connected to the cup.
[0117] The cleaning liquid may include deionized water besides the
post-treatment agent. In this case, the cleaning liquid supply
nozzle may include a post-treatment agent supply nozzle and a
deionized water supply nozzle.
[0118] The wafer transport mechanism is capable of transporting the
wafer from the plating unit to the cleaning unit, so that the
plating process and the cleaning process can successively be
performed on the wafer. The wafer transport mechanism may be
capable of transporting the wafer between the cassette placed on
the cassette stage and the plating unit or the cleaning unit. In
this case, the untreated wafer can be transported from the
cassette, for example, to the plating unit and to the cleaning unit
in sequence by the wafer transport mechanism so as to be
automatically subjected to the plating process and the cleaning
process in sequence and then accommodated again in the cassette
under the control of the system controller.
[0119] When only a small amount of the post-treatment agent remains
in the post-treatment agent tank in the post-treatment agent
supplying section, the post-treatment agent tank may be replaced
with another post-treatment agent tank containing a sufficient
amount of the post-treatment agent. Since the post-treatment agent
tank is housed in the tank enclosure, the post-treatment agent is
unlikely to be scattered out of the tank enclosure even if the
post-treatment agent is splashed during the replacement of the
post-treatment agent tank. Further, the air outlet pipe is
connected to the tank enclosure, so that vapor or mist of the
post-treatment agent generated in the tank enclosure can be
expelled out of the plating apparatus.
[0120] The volume of the vat is preferably equal to or greater than
the volume of the post-treatment agent tank (where a plurality of
post-treatment agent tanks are provided, the total volume of the
plurality of post-treatment agent tanks). Even if the
post-treatment agent entirely leaks out of the post-treatment tank,
the post-treatment agent can be received in the vat.
[0121] In the minor constituent analyzing section, a CVS (cyclic
voltammetric stripping) analysis or a CPVS (cyclic pulse
voltammetric stripping) analysis can be performed on the plating
liquid contained in the analyzing cup with the use of the rotary
platinum electrode. Where the plating liquid contains a plating
accelerating additive (hereinafter referred to simply as
"accelerator") and a plating retarding additive (hereinafter
referred to simply as "retarder") as minor constituents thereof,
the accelerator and the retarder can quantitatively be analyzed
through the CVS analysis or the CPVS analysis.
[0122] Where the concentration of the accelerator or the retarder
is lower than a lower limit of a predetermined concentration range
as the result of the analysis, a replenishment liquid containing
the accelerator or the retarder is added in a proper amount to the
plating liquid so as to adjust the concentration of the accelerator
or the retarder in the predetermined concentration range. Thus, the
plating process can properly be performed on the wafer with the use
of the plating liquid having a properly adjusted accelerator or
retarder concentration.
[0123] Since the wafer treating section is housed in the enclosure,
the plating process, the cleaning process and a like process can be
performed in a clean atmosphere isolated from the external
environment. By exhausting air from the enclosure through the air
outlet pipe, the internal pressure of the enclosure can be reduced
to a negative pressure, and external air from which contaminants
are removed by the filter can be introduced into the enclosure.
[0124] The external air may be forced into the enclosure through
the filter by fans and let out from the air outlet opening. Thus,
down-flow of clean air occurs in the enclosure.
[0125] Deionized water can be supplied into the wafer treating
section through the deionized water pipe introduced into the
enclosure through the deionized water pipe introduction port
provided in the enclosure. The deionized water may be used, for
example, for the cleaning process in the cleaning units. Some of
driving mechanisms employed in the plating units and the cleaning
units may pneumatically be driven. Compressed air for driving these
driving mechanisms can be supplied to the driving mechanisms
through the compressed air pipe introduced into the enclosure
through the compressed air pipe introduction port provided in the
enclosure.
[0126] The operation of the plating apparatus can be controlled on
the basis of the plating apparatus control program stored in the
storage device of the system controller, for example, to
automatically sequentially perform the plating process and the
cleaning process on the untreated wafer. The display may be capable
of displaying the status of the plating apparatus (wafer treating
status). The keyboard may permit the operator to input wafer
treating conditions and the like. Thus, the plating apparatus
ensures easy operation and high productivity.
[0127] In the inventive plating apparatus, the plating vessel may
have an upper edge portion complementary in configuration to a
portion of the cathode ring opposed to the plating vessel, so that
a lower surface of the to-be-treated semiconductor wafer kept in
contact with the cathode can approach the plating vessel so as to
be substantially flush with the upper edge of the plating vessel
without interference between the upper edge portion of the plating
vessel and the cathode ring.
[0128] With this arrangement, the wafer kept in contact with the
cathode can be brought into contact with the plating liquid filled
in the plating vessel and raised from the edge of the plating
vessel without interference between the upper edge portion of the
plating vessel and the cathode ring, because the upper edge portion
of the plating vessel is complementary in configuration to the
portion (lower portion) of the cathode ring opposed to the plating
vessel.
[0129] Since the lower surface of the wafer kept in contact with
the cathode can be brought into substantially flush relation with
the upper edge of the plating vessel, a distance between the lower
surface of the wafer and the upper edge of the plating vessel can
be reduced (e.g., to 0.3 mm to 1.0 mm) in the plating process. In
this case, the plating liquid continuously supplied into the
plating vessel flows in the form of a laminar flow along the lower
surface of the wafer to the peripheral edge of the wafer in the
vicinity of the lower surface of the wafer, and then flows out of
the plating vessel from a gap defined between the upper edge of the
plating vessel and the lower surface of the wafer.
[0130] Even if air bubbles are trapped between the wafer and the
plating liquid, the air bubbles flow together with the plating
liquid out of the plating vessel. The laminar flow of the plating
liquid flowing along the lower surface of the wafer to the
peripheral edge of the wafer and the absence of the air bubbles on
the lower surface of the wafer make it possible to uniformly form a
film by the plating.
[0131] The inventive plating apparatus may further comprise: a
wafer holding mechanism (74a to 74d) to be disposed above the
plating vessel for holding the to-be-treated semiconductor wafer to
bring the semiconductor wafer into contact with the plating liquid
contained in the plating vessel; and a retracting mechanism (222a,
44a) having a pivot shaft (223) generally horizontally disposed at
a lower height than the bottom of the plating vessel and coupled to
the wafer holding mechanism, the retracting mechanism being capable
of pivoting the wafer holding mechanism about the pivot shaft to
move the wafer holding mechanism between an upper position above
the plating vessel and a retracted position apart from the upper
position.
[0132] With this arrangement, the wafer holding mechanism can be
located at the upper position above the plating vessel in the
plating process and retracted from the upper position to the
retracted position in maintenance of the apparatus by the
retracting mechanism.
[0133] The cathode ring may constitute a part of the wafer holding
mechanism.
[0134] The inventive plating apparatus may further comprise: a mesh
member (49) of a resin disposed at a higher height than the anode
in the plating vessel; and a wafer holding mechanism (74a to 74d)
for holding the to-be-treated semiconductor wafer to locate the
semiconductor wafer at a plating position at which the
semiconductor wafer is kept in contact with the plating liquid
filled in the plating vessel; wherein a distance between the
semiconductor wafer located at the plating position and the mesh
member is 0.5 mm to 30 mm.
[0135] With this arrangement, the mesh member is present between
the anode and the wafer held by the wafer holding mechanism in the
plating process, so that the electrical resistance between the
anode and the wafer is greater than the electrical resistance of
the to-be-treated surface of the wafer. Thus, an electric current
uniformly flows across an interface between the wafer and the
plating liquid at different points on the wafer. Therefore, the
film formed by the plating has a substantially uniform
thickness.
[0136] Where the plating liquid can be introduced into the plating
vessel through a pipe connected to the bottom of the plating
vessel, the plating liquid flows upward from a lower side in the
plating vessel. At this time, contaminants in the plating liquid
can be removed by the mesh member. Further, the plating liquid
flowing upward from the lower side of the plating vessel is
rectified into a virtually uniform upward flow by the mesh
member.
[0137] Since the wafer located at the plating position and the mesh
member are spaced only 0.5 mm to 30 mm from each other in adjacent
relation, the plating liquid is drawn by the wafer in a narrowly
limited region when the wafer is rotated in contact with the
plating liquid. This suppresses the eddy flow of the plating liquid
which is unwanted for the plating. Thus, the film formed by the
plating has a uniform thickness.
[0138] The inventive plating apparatus may further comprise: a
shower head (75) for diffusively introducing the plating liquid
into the plating vessel from a plating liquid introduction port
(54) provided in the bottom of the plating vessel; and a mesh
member (49) of a resin disposed at a higher height than the shower
head in the plating vessel; wherein the anode has a mesh shape and
is located at a height between the shower head and the mesh
member.
[0139] With this arrangement, the plating liquid can diffusively be
introduced in various directions (at various angles) into the
plating vessel by the shower head. The plating liquid is introduced
into the plating vessel from the plating liquid introduction port
provided in the bottom of the plating vessel, so that the plating
liquid flows upward from a lower side in the form of an upward flow
in the plating vessel. Since the anode is of a mesh shape, the
plating liquid can pass upwardly through the anode.
[0140] The plating liquid flows further upward to pass upwardly
through the mesh member disposed at a higher height than the anode.
At this time, the plating liquid is rectified into a uniform upward
flow. Therefore, the uniformity of the film formed by the plating
can be improved by keeping the wafer in contact with the rectified
plating liquid in the plating process.
[0141] The inventive plating apparatus may further comprise a
cathode cleaning liquid supplying mechanism (81) for supplying a
cathode cleaning liquid to the cathode for cleaning the cathode in
the plating process.
[0142] With this arrangement, the cathode cleaning liquid can be
supplied to the cathode for the cleaning of the cathode, so that
the plating process can be performed with the cathode kept
clean.
[0143] The inventive plating apparatus may further comprise: a
liquid supplying mechanism (81) for supplying liquid to a
restriction region (80f) where intrusion of the plating liquid is
prevented in the plating apparatus, the restriction region having a
liquid inlet and a liquid outlet; and a conductivity meter (212)
for measuring the electrical conductivity of the liquid flowing out
of the outlet of the restriction region.
[0144] The plating liquid may usually be prevented from intruding
into the restriction region. With this arrangement, if the plating
liquid happens to intrude into the restriction region for some
reason, the plating liquid flows together with the liquid supplied
by the liquid supplying mechanism to reach the conductivity meter.
Where the liquid supplied by the liquid supplying mechanism and the
plating liquid differ in electrical conductivity, the intrusion of
the plating liquid into the restriction region where the intrusion
of the plating liquid is usually prevented can be detected on the
basis of the electrical conductivity measured by the conductivity
meter.
[0145] The restriction region may be a region of the cathode ring
where the intrusion of the plating liquid is prevented.
Alternatively, the restriction region may be the inside of a
through-hole having an outlet and an inlet or a planar region
having a surface on which the liquid flows.
[0146] The inventive plating apparatus may further comprise: a
recovery vessel (62a to 62d) disposed around the plating vessel for
recovering the plating liquid overflowing from the plating vessel;
and a cathode cleaning liquid collection vessel (210) disposed
around the recovery vessel for collecting the cathode cleaning
liquid used for cleaning the cathode kept in contact with the
to-be-treated semiconductor wafer in the plating process.
[0147] With this arrangement, the plating liquid and the cathode
cleaning liquid can separately be collected by the recovery vessel
and the cathode cleaning liquid collection vessel.
[0148] The inventive plating apparatus may further comprise a
plating power source (82) for applying a voltage between the anode
and the cathode, wherein an electrical conduction path between the
anode and the plating power source and an electrical conduction
path between the cathode and the plating power source are isolated
from the ground.
[0149] With this arrangement, the electrical conduction path
between the anode and the plating power source and the electrical
conduction path between the cathode and the plating power source
are not connected to the ground, whereby an electric current is
prevented from flowing through unintended portions in the plating
apparatus, and a noise is prevented from interfering with electric
currents flowing between the anode and the plating power source and
between the cathode and the plating power source.
[0150] In the inventive plating apparatus, the plating units may
each further comprise: a wafer holding mechanism (74a to 74d) for
holding the to-be-treated semiconductor wafer; a first rotary shaft
(77) having a first electrical conduction line (198) electrically
connected to the cathode, and coupled to the wafer holding
mechanism; a rotative driving mechanism (45) for rotating the
semiconductor wafer held by the wafer holding mechanism about the
first rotary shaft; a second rotary shaft (194) having a second
electrical conduction line (194); a rotation force transmission
mechanism (193, 195, 196) for transmitting a rotative driving force
between the first rotary shaft and the second rotary shaft and
establishing an electrical conduction path between the first and
second electrical conduction lines; and a rotary connector (197)
attached to one end of the second rotary shaft and electrically
connected to the second electrical conduction line.
[0151] With this arrangement, an electrical conduction path is
established as extending from the rotary connector to the cathode
through the second electrical conduction line, the rotation force
transmission mechanism and the first electrical conduction line.
Thus, an electrical conduction path can be established between the
plating power source connected to the rotary connector on the side
of a stationary system and the cathode.
[0152] The rotation speed of the second rotary shaft can be reduced
as compared with the rotation speed of the first rotary shaft by
the rotation force transmission mechanism. Thus, the rotary
connector can be rotated at a lower rotation speed for reduction of
a load exerted on the rotary connector, whereby the service life of
the rotary connector can be extended.
[0153] In the inventive plating apparatus, the plating units may
each further comprise: a treatment fluid supplying member (203,
81b) having a fluid channel (81c) formed therein for supplying a
treatment fluid to the to-be-treated wafer; and a rotary joint
(191) being disposed in the treatment fluid supplying member, and
including a rotor (244), a stator (243) and a sliding portion
defined between the rotor and the stator, the rotary joint having a
main channel (270) to constitute a part of the fluid channel and a
leak channel (271) branched from the main channel, the sliding
portion being disposed in the leak channel.
[0154] With this arrangement, the treatment fluid can be supplied
to the to-be-treated wafer from a treatment fluid supply source
located on the side of the stationary system via the rotary joint
even if the to-be-treated wafer is rotated together with a part of
the treatment fluid supplying member. Since the sliding portion is
disposed in the leak channel, particles generated around the
sliding portion can be expelled out of the rotary joint through the
leak channel. Thus, the particles generated around the sliding
portion are prevented from being supplied to the to-be-treated
wafer.
[0155] In the inventive plating apparatus, the cathodering may
comprise: a first electrically conductive member (80c) provided in
the cathode ring and electrically connected to a plating power
source (82); a second electrically conductive member (80d) provided
in the cathode ring and electrically connected to the cathode; and
a third electrically conductive member (80e) provided between the
first electrically conductive member and the second electrically
conductive member, the third electrically conductive member being
resilient and kept in resilient contact with the first and second
electrically conductive members for electrical connection between
the first electrically conductive member and the second
electrically conductive member.
[0156] With this arrangement, the electrical connection between the
first electrically conductive member and the second electrically
conductive member can be maintained by keeping the third
electrically conductive member in resilient contact with the first
and second electrically conductive members, even if the cathode
ring is warped. Thus, an electric current is allowed to flow
between the plating power source and the cathode.
[0157] In the inventive plating apparatus, the cathode may be
adapted to be brought into contact with a peripheral edge portion
of the semiconductor wafer, and the cathode ring may comprise: a
ring-shaped support member (80b, 80u) which supports the cathode;
an electrically conductive member (80d, 80e, 80c) provided in the
support member and establishing an electrical conduction path
between the cathode and a plating power source (82); and a seal
member (80r) provided between the support member and the
electrically conductive member for providing a seal for prevention
of intrusion of the plating liquid into the support member.
[0158] With this arrangement, the electrical conduction path is
established as extending from the plating power source to the
cathode through the electrically conductive member. Thus, the
electrolytic plating process can be performed on the wafer by
electrically energizing the wafer kept in contact with the cathode
by the plating power source.
[0159] Further, the seal member prevents the intrusion of the
plating liquid into the support member to keep the inside of the
support member clean.
[0160] In the inventive plating apparatus, the plating units may
each further comprise a spin base (78) which supports the cathode
ring, and the cathode ring may further comprise a positioning
member (78j, 79j) for fixing the cathode ring in a predetermined
position with respect to the spin base.
[0161] With this arrangement, the cathode ring can easily be fixed
in the predetermined position with respect to the spin base by the
positioning member. The predetermined position herein means a
position at which the center axis of the cathode ring generally
coincides with the rotation axis of the spin base. Thus, the
cathode ring can properly be rotated together with the spin
base.
[0162] In the inventive plating apparatus, the cathode may be
adapted to be brought into contact with the peripheral edge portion
of the semiconductor wafer, and the cathode ring may further
comprise an abutment portion (80a) for holding the semiconductor
wafer in abutment against the semiconductor wafer, the abutment
portion being composed of a rigid material and having a sealing
surface (80s) for sealing the peripheral edge portion of the
semiconductor wafer.
[0163] With this arrangement, an area of the wafer to be brought
into contact with the plating liquid can be limited by sealing the
peripheral edge portion of the wafer by the sealing surface.
[0164] Since the abutment portion is composed of the rigid
material, the size of the abutment portion and its periphery can be
reduced.
[0165] The foregoing and other objects, features and effects of the
present invention will become more apparent from the following
description of the preferred embodiments with reference to the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0166] FIG. 1 is a block diagram illustrating the construction of a
plating apparatus according to one embodiment of the present
invention;
[0167] FIG. 2 is a schematic plan view of a wafer treating
section;
[0168] FIG. 3 is a schematic perspective view illustrating the
construction of an enclosure of the wafer treating section;
[0169] FIG. 4 is a schematic sectional view illustrating a jack
bolt and a frame attached to the enclosure;
[0170] FIG. 5(a) is a schematic plan view for explaining the
construction of a robot body provided in the wafer treating
section;
[0171] FIG. 5(b) is a schematic side view for explaining the
construction of the robot body provided in the wafer treating
section;
[0172] FIG. 5(c) is a schematic front view for explaining the
construction of the robot body provided in the wafer treating
section;
[0173] FIG. 6(a) is a schematic plan view of a cassette stage on
which a cassette is placed;
[0174] FIG. 6(b) is a schematic side view of the cassette stage on
which the cassette is placed;
[0175] FIG. 7 is a schematic front view illustrating the
construction of a plating section;
[0176] FIG. 8 is a diagram illustrating a relationship between the
concentrations of copper in plating liquid samples and measured
absorbances;
[0177] FIG. 9 is a schematic sectional view illustrating the
construction of a plating unit;
[0178] FIG. 10 is a schematic sectional view illustrating a portion
around a rotary pipe on a greater scale;
[0179] FIG. 11 is a schematic sectional view of a rotary joint;
[0180] FIG. 12 is a schematic sectional view illustrating a portion
around a wafer as observed in a plating process;
[0181] FIG. 13(a) is a schematic plan view illustrating the entire
cathode ring (as viewed from the side of a spin base);
[0182] FIG. 13(b) is a schematic sectional view illustrating the
entire cathode ring;
[0183] FIG. 13(c) is a schematic plan view illustrating an inner
peripheral portion of the cathode ring on a greater scale;
[0184] FIG. 14(a) is a schematic plan view illustrating the entire
cathode;
[0185] FIG. 14(b) is a schematic plan view illustrating a part of
the cathode on a greater scale;
[0186] FIG. 14(c) is a schematic sectional view illustrating a part
of the cathode on a greater scale;
[0187] FIG. 15 is a schematic diagram illustrating an electrical
equivalent circuit in a plating vessel;
[0188] FIG. 16 is a schematic plan view of a plating cup;
[0189] FIG. 17 is a schematic sectional view illustrating a portion
around a deionized water supply nozzle;
[0190] FIG. 18 is a schematic sectional view illustrating a portion
around a liquid trap;
[0191] FIG. 19 is a schematic sectional view illustrating a portion
around a junction between an air outlet pipe and a cathode cleaning
liquid collection vessel;
[0192] FIG. 20 is a schematic sectional view illustrating the
plating unit with the spin base facing upward;
[0193] FIG. 21 is a schematic side view of the plating unit;
[0194] FIG. 22 is a schematic side view of the plating cup;
[0195] FIG. 23 is a schematic sectional view illustrating the
construction of a bevel etching unit;
[0196] FIG. 24 is a schematic sectional view illustrating the
construction of a cleaning unit;
[0197] FIG. 25 is a block diagram illustrating the construction of
a control system for the wafer treating section;
[0198] FIG. 26 is a schematic diagram illustrating the construction
of a major constituent managing section;
[0199] FIG. 27 is a schematic diagram illustrating the construction
of an analyzing cup provided in a minor constituent managing
section;
[0200] FIG. 28 is a schematic perspective view illustrating the
construction of a post-treatment agent supplying section; and
[0201] FIG. 29 is a block diagram illustrating the construction of
control systems for the major constituent managing section, the
minor constituent managing section and the post-treatment agent
supplying section.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0202] FIG. 1 is a block diagram illustrating the construction of a
plating apparatus 10 according to one embodiment of the present
invention.
[0203] The plating apparatus 10 includes a wafer treating section 1
for plating a surface of a semiconductor wafer (hereinafter
referred to simply as "wafer") with the use of a plating liquid and
etching (bevel-etching) a peripheral edge of the wafer after the
plating, a major constituent managing section 2 having a copper
supply source for supplying copper ions to the plating liquid for
management of the concentrations of major constituents of the
plating liquid, a minor constituent managing section 3 for managing
minor constituents of the plating liquid, and a post-treatment
agent supplying section 4 for supplying a post-treatment agent to
the wafer treating section for post-treatment of the wafer after
the plating. The plating apparatus 10 is disposed in a clean
room.
[0204] The plating liquid for use in the wafer treating section 1
contains sulfuric acid (supporting electrolyte), copper ions
(target metal), iron (oxidizing/reducing agent) and water as major
constituents thereof. The plating liquid further contains chlorine,
a plating accelerating additive (brightener) and a plating
retarding additive (suppresser) as minor constituents thereof.
[0205] Two plating liquid transport pipes P12a, P12b extend between
the wafer treating section 1 and the major constituent managing
section 2 for transporting the plating liquid between these
sections in opposite directions. Similarly, a sampling pipe 322 and
a replenishment pipe 324 extend between the wafer treating section
1 and the minor constituent managing section 3 for transporting the
plating liquid between these sections in opposite directions.
Further, a post-treatment agent pipe P14 extends between the wafer
treating section 1 and the post-treatment agent supplying section 4
for supplying the post-treatment agent from the post-treatment
agent supplying section 4 to the wafer treating section 1.
[0206] The wafer treating section 1 includes a system controller
for controlling the entire plating apparatus 10. The wafer treating
section 1 is connected to the major constituent managing section 2,
the minor constituent managing section 3 and the post-treatment
agent supplying section 4 via signal lines L12, L13 and L14,
respectively. The operations of the major constituent managing
section 2, the minor constituent managing section 3 and the
post-treatment agent supplying section 4 are controlled by the
system controller provided in the wafer treating section 1.
[0207] The plating liquid being used in the wafer treating section
1 is transported (sampled) into the minor constituent managing
section 3 through the sampling pipe 322. The minor constituent
managing section 3 has an analyzing cup in which at least one of
the minor constituents of the plating liquid transported from the
wafer treating section 1 can be analyzed through a CVS (cyclic
voltammetric stripping) analysis.
[0208] The minor constituent managing section 3 includes a minor
constituent management controller, which is capable of calculating
the amounts of the minor constituents to be added to the plating
liquid in the wafer treating section 1 so as to adjust the
concentrations of the minor constituents of the plating liquid on
the basis of the results of the CVS analysis. Under the control of
the minor constituent management controller, the minor constituents
are supplied in the amounts thus calculated to the plating liquid
in the wafer treating section 1 through the replenishment pipe
324.
[0209] The post-treatment agent supplying section 4 includes an
agent tank containing the post-treatment agent, and an agent supply
mechanism for supplying the post-treatment agent from the agent
tank to the wafer treating section 1. Examples of the
post-treatment agent include an etching liquid to be used for the
bevel etching and a cleaning liquid.
[0210] FIG. 2 is a schematic plan view of the wafer treating
section 1.
[0211] The wafer treating section 1 is adapted to perform a plating
process for forming a thin copper film on the surface of the wafer
W, then perform an etching process for etching the peripheral edge
of the wafer W, and perform a cleaning process for cleaning the
entire surfaces of the wafer W.
[0212] A wafer loading/unloading section 19 is disposed along a
first transport path 14 extending linearly horizontally. In the
wafer loading/unloading section 19, a plurality of cassette stages
16 (four cassette stages in this embodiment) which are each adapted
to receive thereon one cassette C capable of accommodating a wafer
W are arranged along the first transport path 14. The wafer W is of
a generally round shape, and has a multiplicity of fine holes or
grooves formed in the to-be-treated (to-be-plated) surface thereof
and a barrier layer and a copper seed layer formed on the surface
thereof.
[0213] A second linear transport path 15 is provided horizontally
and perpendicularly to the first transport path 14. In this
embodiment, the second transport path 15 extends from a middle
portion of the first transport path 14. A plating section 12
including four plating units 20a to 20d arranged along the second
transport path 15 is provided on one side of the second transport
path 15. The plating units 20a to 20d are each adapted to plate the
surface of the wafer W with copper.
[0214] A post-treatment section 13 including two bevel etching
units 21a, 21 band two cleaning units (spin cleaning units) 22a,
22b arranged along the second transport path 15 is provided on the
other side of the second transport path 15. The bevel etching units
21a, 21b are each adapted to etch the peripheral edge of the wafer
W, while the cleaning units 22a, 22b are each adapted to clean
opposite sides of the wafer W.
[0215] The first transport path 14 and the second transport path 15
constitute a T-shaped transport path, and a single transport robot
TR is provided on the T-shaped transport path. The transport robot
TR includes transport guide rails 17 disposed along the second
transport path 15, and a robot body 18 movable along the transport
guide rails 17. The operation of the transport robot TR is
controlled by a transport controller 29.
[0216] The robot body 18 is capable of transporting the wafer W
along the first transport path 14 and along the second transport
path 15. Therefore, the robot body 18 can access any of the
cassettes C placed on the cassette stages 16 to load and unload a
wafer W, and access any of the plating units 20a to 20d, the bevel
etching units 21a, 21b and the cleaning unit 22a, 22b to load and
unload the wafer W.
[0217] A basic wafer transport route and a basic process sequence
are as follows. First, an untreated wafer W is unloaded from one of
the cassettes C, then transported to the front of one of the
plating units 20a to 20d, and loaded into the plating unit 20a to
20d by the robot body 18 so as to be subjected to the plating
process. In turn, the wafer W subjected to the plating process is
unloaded from the plating unit 20a to 20d, and loaded into one of
the bevel etching units 21a, 21b so as to be subjected to the bevel
etching process.
[0218] Subsequently, the wafer W subjected to the bevel etching
process is unloaded from the bevel etching unit 21a, 21b, then
transported along the second transport path 15, and loaded in to
one of the cleaning units 22a, 22b by the robot body 18 so as to be
subjected to the cleaning process.
[0219] Further, the wafer W subjected to the cleaning process is
unloaded from the cleaning unit 22a, 22b and then transported along
the second transport path 15 toward the first transport path 14 by
the robot body 18. Upon reaching the first transport path 14, the
robot body 18 starts moving along the first transport path 14
toward a cassette C placed on one of the cassette stages 16, and
loads the wafer W on the cassette C.
[0220] FIG. 3 is a schematic perspective view illustrating the
construction of an enclosure 30 of the wafer treating section
1.
[0221] The enclosure 30 has a generally rectangular box-like outer
shape defined by a plurality of barrier walls (boundary walls) for
isolating the inside thereof from the external environment. In the
enclosure 30, partition walls are provided between the second
transport path 15 and the plating section 12 and between the second
transport path 15 and the post-treatment section 13. The space of
the second transport path 15 is isolated from the space of the
plating section 12 and from the space of the post-treatment section
13 by the partition walls, except when the wafer W is loaded and
unloaded with respect to these sections.
[0222] A filter 31 for filtering off contaminants in air is
provided in a top barrier wall of the enclosure 30. The filter 31
includes a first filter 31a disposed above the cassette stages 16,
the first transport path 14 and the second transport path 15, and a
second filter 31b disposed above the post-treatment section 13.
Fans not shown are provided above the first filter 31a for forcibly
introducing external air into the enclosure 30.
[0223] The cassette stage 16 is separated from the first transport
path 14 by a barrier wall. This barrier wall has wafer
loading/unloading ports Wh, through which the cassettes C placed on
the cassette stages 16 are accessed from the first transport path
14 for the loading and unloading of the wafer W.
[0224] A plurality of slit-like openings 36 are provided in a
portion of the enclosure 30 below the second transport path 15 as
extending longitudinally of the second transport path 15. Since the
space of the second transport path 15 is isolated by the enclosure
30 and the internal partitions, the space of the second transport
path 15 is kept at a positive pressure when air is forcibly
introduced into the enclosure 30 through the first filter 31a.
Therefore, internal air is exhausted from the enclosure 30 through
the openings 36. Thus, air flows from the upper side toward the
lower side (the down-flow of air occurs) in the space of the second
transport path 15.
[0225] Since no reagent is used in the space of the second
transport path 15, the air flowing through this space is not
contaminated. Therefore, the air flowing through the space of the
second transport path 15 is exhausted through the openings 36
around the enclosure 30.
[0226] Air outlet ports 34h, 35h are respectively provided in a
lower portion of a barrier wall defining the plating section 12 and
a lower portion of a barrier wall defining the post-treatment
section 13 on a side of the enclosure 30 opposite from the cassette
stages 16. The air outlet port 34h is connected to one end of an
air outlet duct 34, while the air outlet port 35h is connected to
one end of an air outlet duct 35. The other ends of the air outlet
ducts 34, 35 are connected to an in-plant exhauster system line.
Thus, air possibly exposed to the plating liquid and the
post-treatment agent in the plating section 12 and the
post-treatment section 13 can forcibly be exhausted outside the
clean room.
[0227] By forcibly exhausting the air from the post-treatment
section 13 through the air outlet port 35h, the internal pressure
of the post-treatment section 13 is kept at a negative pressure, so
that external air is sucked into the post-treatment section 13
through the second filter 31b. Thus, air flows downward in the
space of the post-treatment section 13.
[0228] A deionized water pipe introduction port 32h and a
compressed air pipe introduction port 33h are provided in the
vicinity of the air outlet port 35h in the barrier wall formed with
the air outlet port 35h. A deionized water pipe 32 and a compressed
air pipe 33 for supplying deionized water and compressed air for
use in the wafer treating section 1 are introduced into the wafer
treating section 1 through the deionized water pipe introduction
port 32h and the compressed air introduction port 33h,
respectively.
[0229] A frame 37 formed by combining iron structural parts is
attached to a lower peripheral edge of the enclosure 30 to support
the entire wafer treating section 1. A plurality of jack bolts 38
are attached to the frame 37 as properly spaced longitudinally of
the structural parts of the frame 37. The frame 37 is supported by
the jack bolts 38 so as to be spaced a predetermined distance from
the floor of the clean room in which the wafer treating section 1
is disposed.
[0230] FIG. 4 is a schematic sectional view illustrating the jack
bolt 38 and the frame 37.
[0231] The structural parts of the frame 37 each have a laterally
open U-shaped cross section, and include two generally horizontal
and parallel plate portions. A lower one of the plate portions
serves as a support plate 37a which has an internal thread portion.
The jack bolt 38 includes a bolt portion 38b having an external
thread portion provided on its circumference, a generally round
base disk 38a fixed generally perpendicularly to a lower end of the
bolt portion 38b, and a lock nut 38c fitted around the bolt portion
38b.
[0232] The bolt portion 38b is engaged with the internal thread
portion of the support plate 37a and extends generally vertically
through the support plate 37a. The lock nut 38c is tightened toward
the support plate 37a from the lower side of the support plate 37a.
A distance between the base disk 38a and the support plate 37a,
i.e., the height of the frame 37 from the floor of the clean room,
is adjustable by variably positioning the support plate 37a with
respect to the length of the bolt portion 38b.
[0233] For the adjustment of the height of the frame 37, the lock
nut 38c is loosened (the lock nut 38c is rotated with respect to
the bolt portion 38b so as to be moved apart from the support plate
37a), and then the base disk 38a is rotated in a proper direction.
Thus, the bolt portion 38b is rotated together with the base disk
38a, so that the position of the support plate 37a with respect to
the length of the bolt portion 38b is changed for the adjustment of
the height of the frame 37 from the floor of the clean room. After
the adjustment, the lock nut 38c is tightened toward the support
plate 37a, whereby the bolt portion 38b is locked with respect to
the support plate 37a.
[0234] The plurality of jack bolts 38 attached to the frame 37 have
the same construction as shown in FIG. 4. Therefore, the leveling
adjustment of the wafer treating section 1 can be achieved by
attaching at least three jack bolts 38 to the frame 37 in a
non-aligned manner and adjusting the positions of the support
plates 37a with respect to the lengths of the bolt portions
38b.
[0235] FIGS. 5(a), 5(b) and 5(c) are a schematic plan view, a
schematic side view and a schematic front view, respectively, for
explaining the construction of the robot body 18.
[0236] The robot body 18 includes a base 23, a vertical articulated
arm 24 attached to the base 23, a pivotal driving mechanism 25
attached to the vertical articulated arm 24, and a substrate holder
26 to be driven pivotally about a vertical pivot axis V0 by the
pivotal driving mechanism 25 (only the substrate holder 26 is shown
in FIG. 5(a)).
[0237] The substrate holder 26 includes a body 40 having a flat
top, and a pair of retractable arms 41, 42 provided on the flat top
of the body 40. A retractable driving mechanism (not shown) for
horizontally advancing and retracting the pair of retractable arms
41, 42 is incorporated in the body 40.
[0238] The retractable arms 41 and 42 respectively include first
arm portions 41a and 42a, second arm portions 41b and 42b, and
substrate holder hands (effecters) 41c and 42c. The body 40 has a
generally round shape as seen in plan, and the first arm portions
41a, 42a are attached to a peripheral edge portion of the body 40
pivotally about vertical pivot axes thereof. The first arm portions
41a, 42a are driven pivotally about the pivot axes by the
retractable driving mechanism provided in the body 40.
[0239] The retractable arms 41, 42 each constitute a so-called
scholar robot, which is operative so that the second arm portion
41b, 42b is pivoted about a vertical pivot axis thereof in
synchronization with the pivoting of the first arm portion 41a,
42a. Thus, the first arm portion 41a, 42a and the second arm
portion 41b, 42b of the retractable arm 41, 42 are stretched and
unstretched so as to advance and retract the substrate holder hand
41c, 42c.
[0240] When the retractable arms 41, 42 are in an unstretched
state, the substrate holder hands 41c, 42c are kept in vertically
overlapped relation (FIG. 5(a)). Therefore, the substrate holder
hand 41c of the retractable arm 41 has a bent shape for prevention
of interference with the substrate holder hand 42c of the
retractable arm 42 (FIG. 5(b)).
[0241] The vertical articulated arm 24 includes a first arm 24a and
a second arm 24b. The first arm 24a is attached to the base 23 so
that the first arm 24a is pivotal about a horizontal pivot axis H1
at one end thereof. The second arm 24b is attached to the other end
of the first arm 24a pivotally about a horizontal pivot axis H2 at
one end thereof. The pivotal driving mechanism 25 is attached to
the other end of the second arm 24b pivotally about a horizontal
pivot axis H3. The pivot axes H1, H2 and H3 are parallel to each
other.
[0242] A motor 27 for pivoting the first arm 24a is provided in the
base 23, and a motor 28 for pivotally driving the second arm 24b is
provided in a coupling between the first arm 24a and the second arm
24b. The motor 28 is rotatable in synchronization with the motor
27. A driving force transmission mechanism (not shown) for
transmitting a driving force from the motor 28 to the pivotal
driving mechanism 25 is incorporated in the second arm 24b. Thus,
the pivotal driving mechanism 25 can constantly hold the substrate
holder 26 in the same attitude (e.g., in such an attitude as to
hold the wafer W horizontally), even if the first arm 24a and the
second arm 24b are pivoted.
[0243] A motor (not shown) is incorporated in the pivotal driving
mechanism 25. The pivotal driving mechanism 25 receives a driving
force from this motor to pivotally drive the substrate holder 26
about the vertical pivot axis V0.
[0244] With this arrangement, the transport robot TR can move the
substrate holder hands 41c, 42c horizontally and vertically within
a range hatched in FIG. 5(c).
[0245] When the robot body 18 accesses the cassette C placed on the
cassette stage 16 (see FIG. 2), the robot body 18 is moved to ends
of the transport guide rails 17 on the side of the first transport
path 14 by the transport controller 29. In this state, the
substrate holder 26 is brought into opposed relation to the
cassette C on the cassette stage 16 by the operation of the
vertical articulated arm 24. That is, the substrate holder 26 can
be moved along the first transport path 14, while the base 23 is
kept located on the transport guide rails 17.
[0246] Then, the retractable arm 41, 42 is brought into opposed
relation to the cassette C by the operation of the pivotal driving
mechanism 25, and caused to access the cassette C by the
retractable driving mechanism not shown for loading and unloading
the wafer W with respect to the cassette C. When the wafer W is
transferred between the cassette C and the retractable arm 41, 42,
the substrate holder 26 is slightly moved up or down by the
operation of the vertical articulated arm 24.
[0247] When the robot body 18 accesses any of the plating units 20a
to 20d, the bevel etching units 21a, 21b and the cleaning units
22a, 22b (see FIG. 2), the robot body 18 is moved to the front of
the corresponding unit on the transport guide rails 17 by a
movement mechanism not shown. In this state, the substrate holder
26 is moved up or down to the height of a substrate
loading/unloading port of the unit by the operation of the vertical
articulated arm 24, and the retractable arm 41, 42 is brought into
opposed relation to the unit by pivoting the substrate holder 26 by
means of the pivotal driving mechanism 25.
[0248] In this state, the retractable arm 41, 42 is caused to
access the unit by the retractable driving mechanism for the
loading and unloading of the wafer W. When the wafer W is
transferred between the unit and the retractable arm 41, 42, the
substrate holder 26 is slightly moved up or down by the operation
of the vertical articulated arm 24.
[0249] With this arrangement, the cassette C, the plating units 20a
to 20d, the bevel etching units 21a, 21b and the cleaning units
22a, 22b can be accessed by the single robot body 18 for the
loading and unloading of the wafer W.
[0250] The wafer W subjected to the plating process in the plating
unit 20a to 20d (hereinafter referred to as "entire-surface-plated
wafer") has a copper film formed on the entire surface thereof
including the peripheral edge thereof by the plating, before the
wafer W is subjected to the bevel etching process in the bevel
etching unit 21a, 21b. Therefore, the substrate holder hand 41c,
42c which holds the entire-surface-plated wafer is contaminated
with copper. Hence, it is preferred that one of the substrate
holder hands 41c, 42c is dedicated to holding the
entire-surface-plated wafer. Thus, the contamination with copper is
prevented from spreading via the substrate holder hand 41c or
42c.
[0251] FIGS. 6(a) and 6(b) are a schematic plan view and a
schematic side view, respectively, of the cassette stage 16 on
which the cassette C is placed.
[0252] The cassette stage 16 includes a planar cassette base 50 for
receiving thereon the cassette C. The cassette base 50 has a
generally square shape as seen in plan. The cassette C has a
generally square shape having a smaller size than the cassette base
50 as seen in plan, and has a wafer loading/unloading opening Ce
provided on one lateral side thereof.
[0253] The cassette base 50 has cassette guides 51 provided on one
surface (upper surface) thereof in association with four corners of
the cassette C as seen in plan. Therefore, the cassette C can be
located in position on the cassette base 50 with its corners in
contact with the cassette guides 51. With the cassette C located in
position on the cassette base 50, the wafer loading/unloading
opening Ce faces toward the first transport path 14 (see FIG.
2).
[0254] A light emitting element 52a and a light receiving element
52b are respectively provided at generally middle points on
opposite edges of the cassette base 50 (excluding an edge having
the wafer loading/unloading opening Ce) on the surface of the
cassette base 50. The light emitting element 52a and the light
receiving element 52b constitute a transmissive photosensor 52.
When no cassette C is present on the cassette base 50, light
emitted from the light emitting element 52a is received by the
light receiving element 52b. When the cassette C is present on the
cassette base 50, the light emitted from the light emitting element
52a is blocked by the cassette C and does not reach the light
receiving element 52b. Thus, a judgment can be made on the presence
or absence of the cassette C on the cassette base 50.
[0255] FIG. 7 is a schematic front view illustrating the
construction of the plating section 12.
[0256] The plating section 12 includes a plurality of plating units
(the four plating units 20a to 20d in this embodiment) for the
plating of the wafer W, and a plating liquid container 55 for
containing the plating liquid. The plating units 20a to 20d
respectively include plating cups 56a to 56d for containing the
plating liquid, and wafer holding/rotating mechanisms (treatment
heads) 74a to 74d to be located above the plating cups 56a to
56d.
[0257] The plating liquid container 55 is capable of containing the
plating liquid in a much greater amount than the plating cups 56a
to 56d (e.g., 20 times the total volume of the plating cups 56a to
56d). Since a great amount of the plating liquid can be stored in
the plating liquid container 55, the total amount of the plating
liquid to be used in the plating section 12 can be increased. Thus,
variations in the composition of the plating liquid can be reduced
during the plating process.
[0258] The plating liquid transport pipe P12a for transporting the
plating liquid to the major constituent managing section 2 is
connected to the bottom of the plating liquid container 55 in
communication with the plating liquid container 55. The plating
liquid transport pipe P12b for introducing the plating liquid
transported from the major constituent managing section 2 into the
plating liquid container 55, the sampling pipe 322 for transporting
the plating liquid to the minor constituent managing section 3, and
the replenishment pipe 324 for transporting the plating liquid
between the minor constituent managing section 3 and the plating
liquid container 55 in opposite directions are introduced into the
plating liquid container 55 from the top of the plating liquid
container 55. The plating liquid transport pipe P12b, the sampling
pipe 322 and the replenishment pipe 324 extend to a depth at which
open ends thereof are submerged in the plating liquid in the
plating liquid container 55.
[0259] The plating cups 56a to 56d are located at a higher position
than the plating liquid container 55. A liquid supply pipe 57
extends from the bottom of the plating liquid container 55, and is
branched into four branch liquid supply pipes 58a to 58d. The
branch liquid supply pipes 58a to 58d extend upward to be
respectively connected to bottom center portions of the plating
cups 56a to 56d in communication with the plating cups 56a to
56d.
[0260] Pumps P1 to P4, filters 59a to 59d and flow meters 60a to
60d are provided in this order from a lower side to an upper side
in the respective branch liquid supply pipes 58a to 58d. The pumps
P1 to P4 are respectively capable of pumping the plating liquid
from the plating liquid container 55 to the plating cups 56a to
56d. The operations of the pumps P1 to P4 are controlled by the
system controller 155. The filters 59a to 59d are capable of
removing particles (contaminants) from the plating liquid. Signals
indicative of the flow rates of the plating liquid is outputted
from the flow meters 60a to 60d, and inputted to the system
controller 155.
[0261] The plating cups 56a to 56d respectively include cylindrical
plating vessels (liquid containing portions) 61a to 61d provided
inwardly thereof, and recovery vessels 62a to 62d surrounding the
plating vessels 61a to 61d. The branch liquid supply pipes 58a to
58d are connected in communication with the plating vessels 61a to
61d. Branch return pipes 63a to 63d extend from bottom portions of
the recovery vessels 62a to 62d. The branch return pipes 63a to 63d
are connected in communication with a return pipe 64, which extends
into the plating liquid container 55.
[0262] With the aforesaid arrangement, the plating liquid is
supplied, for example, to the plating vessel 61a from the plating
liquid container 55 through the liquid supply pipe 57 and the
branch liquid supply pipe 58a by operating the pump P1. The plating
liquid overflows from the top of the plating vessel 61a, and is fed
back into the plating liquid container 55 from the recovery vessel
62a through the branch return pipe 63a and the return pipe 64 by
gravity. That is, the plating liquid is circulated through the
plating liquid container 55 and the plating cup 56a.
[0263] Similarly, the plating liquid is circulated through the
plating liquid container 55 and the plating cup 56b, 56c or 56d by
operating the pump P2, P3 or P4. When the plating process is
performed in any of the plating units 20a to 20d, the plating
liquid is circulated through the plating cup 56a to 56d of the
corresponding plating unit 20a to 20d and the plating liquid
container 55. Thus, the plating liquid container 55 is shared by
the four plating units 20a to 20d.
[0264] One end of a bypass pipe 65 is connected to the branch
liquid supply pipe 58a between the pump P1 and the filter 59a. The
other end of the bypass pipe 65 is introduced into the plating
liquid container 55. Absorptiometers 66A, 66B for measuring
absorbances of the plating liquid at specific wavelengths of light
are provided in the bypass pipe 65. The absorptiometer 66A is
provided for determining the concentration of copper in the plating
liquid, while the absorptiometer 66B is provided for determining
the concentration of iron in the plating liquid.
[0265] When the pump P1 is operated to circulate the plating liquid
through the plating liquid container 55 and the plating cup 56a, a
part of the plating liquid flowing through the branch liquid supply
pipe 58a flows into the bypass pipe 65 due to a pressure loss by
the filter 59a. That is, the plating liquid can be introduced into
the bypass pipe 65 without provision of a dedicated pump in the
bypass pipe 65.
[0266] The absorptiometers 66A, 66B each include a cell 67A, 67B
composed of a transparent material, and a light emitting section
68A, 68B and a light receiving section 69A, 69B disposed in opposed
relation with the cell 67A, 67B interposed therebetween. The light
emitting sections 68A and 68B are respectively capable of emitting
light beams having specific wavelengths corresponding to absorption
spectra of copper and iron (e.g., 780 nm for copper). The light
receiving sections 69A and 69B are respectively capable of
measuring the intensities of the light beams emitted from the light
emitting sections 68A and 68B and transmitted through the plating
liquid in the cells 67A and 67B. The absorbances of the plating
liquid are determined on the basis of the light intensities.
Signals indicative of the absorbances are outputted from the
absorptiometers 66A, 66B, and inputted to the system controller
155.
[0267] A temperature sensor 70 and an electromagnetic conductivity
meter 71 are attached to a side wall of the plating liquid
container 55. The temperature sensor 70 and the electromagnetic
conductivity meter 71 are located at a height lower than the
surface level of the plating liquid contained in the plating liquid
container 55. Detectors of the temperature sensor 70 and the
electromagnetic conductivity meter 71 project into the plating
liquid container 55, and are respectively adapted to measure the
temperature and electrical conductivity of the plating liquid.
Output signals of the temperature sensor 70 and the electromagnetic
conductivity meter 71 are inputted to the system controller
155.
[0268] The concentrations of copper andiron in the plating liquid
can be determined by measuring the absorbances of the plating
liquid at the specific wavelengths of light. An explanation will be
given to how to determine the copper concentration on the basis of
the absorbance of the plating liquid.
[0269] For the determination of the copper concentration of the
plating liquid, a relationship between the copper concentration and
the absorbance is preliminarily determined. First, plural plating
liquid samples having different copper concentrations are prepared.
Copper sulfate is added as a copper source for the preparation of
the plating liquid samples. The plating liquid samples each have
substantially the same composition as the plating liquid actually
used for the plating process, except that the copper concentrations
thereof are different. The absorbances of the plating liquid
samples are measured by the absorptiometer 66A. Thus, the
relationship between the copper concentration and the absorbance
(copper calibration line) is determined on the basis of the known
copper concentrations and the measured absorbances of the plating
liquid samples as shown in FIG. 8.
[0270] For the determination of an unknown copper concentration of
the plating liquid, the absorbance of the plating liquid is
measured by the absorptiometer 66A. Then, the copper concentration
is determined on the basis of the measured absorbance and the
copper calibration line.
[0271] Similarly, a relationship between the iron concentration and
the absorbance (iron calibration line) is preliminarily determined
on the basis of known iron concentrations and measured absorbances
of plating liquid samples, and the concentration of iron in the
plating liquid is determined on the basis of the absorbance of the
plating liquid measured by the absorptiometer 66B and the iron
calibration line.
[0272] The system controller 155 includes a storage device storing
therein data of the copper calibration line and the iron
calibration line. The system controller 155 is capable of
determining the copper concentration on the basis of the output
signal of the absorptiometer 66A and the data of the copper
calibration line, and determining the iron concentration on the
basis of the output signal of the absorptiometer 66B and the data
of the iron calibration line.
[0273] An ultrasonic level meter 72 is provided above the plating
liquid container 55. The ultrasonic level meter 72 is capable of
detecting the surface level of the plating liquid in the plating
liquid container 55. An output signal of the ultrasonic level meter
72 is inputted to the system controller 155. A capacitive level
meter may be employed instead of the ultrasonic level meter 72.
[0274] The plating liquid container 55, the liquid supply pipe 57,
the branch liquid supply pipes 58a to 58d, the branch return pipes
63a to 63d and the return pipe 64 are disposed in a pipe chamber 73
virtually air-tightly enclosed by the enclosure 30 and partition
walls of the wafer treating section 1. The pipe chamber 73 has the
air outlet port 34h, which is connected to the air outlet duct 34.
The other end of the air outlet duct 34 is connected to the
in-plant exhauster system line. The internal pressure of the pipe
chamber 73 is reduced to a negative pressure by air exhaustion
through the exhauster system line, so that air possibly exposed to
the plating liquid and the like in the plating section 12 can
forcibly be exhausted out of the clean room.
[0275] FIG. 9 is a schematic sectional view illustrating the common
construction of the plating units 20a to 20d as observed in the
plating process. The wafer holding/rotating mechanisms 74a to 74d
are each supported by a column-shaped inversion base 181 extending
generally horizontally. An inversion driving section 43 is
connected to one end of the inversion base 181.
[0276] The inversion driving section 43 includes a column-shaped
vertical base 182 extending vertically, a rotary actuator 183
attached to the vertical base 182 and having a rotation shaft
perpendicular to the vertical base 182 and parallel to the
inversion base 181, and a toothed pulley 184 attached to the
rotation shaft of the rotary actuator 183, a toothed pulley 185
attached to a shaft extending parallel to the shaft of the rotary
actuator 183 and supported rotatably by the vertical base 182, and
a timing belt 186 stretched between the toothed pulley 184 and the
toothed pulley 185 for transmitting a rotation force of the rotary
actuator 183.
[0277] The rotary actuator 183 may be, for example, pneumatically
driven. The inversion base 181 is attached to the vicinity of the
shaft of the toothed pulley 185 perpendicularly to the toothed
pulley 185. The inversion base 181 and the wafer holding/rotating
mechanism 74a to 74d supported by the inversion base 181 can be
pivoted (inverted) about the horizontal shaft as indicated by an
arrow a in FIG. 9 by a pivotal driving force of the rotary actuator
183. Thus, the wafer W held by the wafer holding/rotating mechanism
74a to 74d can face upward or downward toward the plating cup 56a
to 56d.
[0278] The vertical base 182 is coupled to a lift mechanism 44. The
lift mechanism 44 includes a column-shaped guide 44a extending
generally vertically, a support member 44b extending from the guide
44a perpendicularly to the length of the guide 44a, a first motor
44c attached to the support member 44b and having a rotation shaft
extending generally vertically, and a ball thread 44d coaxially
attached to the rotation shaft of the first motor 44c The first
motor 44c is located below the ball thread 44d. The first motor 44c
may be, for example, a servo motor.
[0279] A support member 182a having an internal thread portion is
provided in threading engagement with the ball thread 44d in the
vicinity of a lower end of the vertical base 182. The guide 44a
vertically guides the vertical base 182 while preventing the
vertical base 182 from rotating about the axis of the ball thread
44d.
[0280] With this arrangement, the vertical base 182 can be moved
vertically by rotating the first motor 44c. Therefore, the
inversion base 181 coupled to the vertical base 182 and the wafer
holding/rotating mechanism 74a to 74d supported by the inversion
base 181 can vertically be moved up and down (in directions
indicated by arrows b in FIG. 9).
[0281] The wafer holding/rotating mechanism 74a to 74d includes a
rotary pipe 77 and a disk-shaped spin base 78 attached to one end
of the rotary pipe 77 perpendicularly to the rotary pipe 77.
[0282] FIG. 10 is a schematic sectional view illustrating a portion
around the rotary pipe 77 on a greater scale. Referring to FIGS. 9
and 10, the rotary pipe 77 is supported rotatably about its axis by
the inversion base 181 via a bearing 181b.
[0283] A plurality of wafer transfer pins 84 are provided on a
surface of the spin base 78 opposite from the rotary pipe 77
between the center and the peripheral edge of the spin base 78. A
plurality of support posts (e.g., four support posts) 79 are
provided in a peripheral edge portion on the surface of the spin
base 78 opposite from the rotary pipe 77. An annular cathode ring
80 is attached to distal ends of the support posts 79. The support
posts 79 have a greater length than the wafer transfer pins 84.
[0284] The cathode ring 80 has an abutment portion 80a projecting
toward the center of the cathode ring 80. The abutment portion 80a
has an inner diameter slightly smaller than the diameter of the
wafer W. The cathode ring 80 further has a projection 80p
projecting opposite from the support posts 79.
[0285] A susceptor 81 is provided coaxially with the rotary pipe
77. The susceptor 81 includes a support shaft 81b extending through
the rotary pipe 77, and a disk-shaped wafer back side press plate
81a attached to an end of the support shaft 81b (on the side of the
cathode ring 80) perpendicularly to the support shaft 81b. The
support shaft 81b is supported coaxially with the rotary pipe 77 by
a ball spline 190, while being permitted to move axially of the
rotary pipe 77.
[0286] The wafer back side press plate 81a is surrounded by the
plurality of support posts 79. The wafer back side press plate 81a
has a slightly smaller diameter than the wafer W. An end portion of
the support shaft 81b opposite from the wafer back side press plate
81a projects out of the rotary pipe 77.
[0287] The susceptor 81 is coupled to a susceptor movement
mechanism 46. The susceptor movement mechanism 46 includes an air
cylinder 46a attached to the inversion base 181 and having a piston
extending parallel to the support shaft 81b, and a transmission
member 46b which couples the piston of the air cylinder 46a to the
support shaft 81b. The transmission member 46b is fixed to the end
portion of the support shaft 81b projecting out of the rotary pipe
77 opposite from the wafer back side press plate 81a. The susceptor
81 can be moved along the center axis of the rotary pipe 77 by
driving the air cylinder 46a.
[0288] The wafer back side press plate 81a is formed with holes in
association with the wafer transfer pins 84. Thus, the wafer
transfer pins 84 are inserted into the holes of the wafer back side
press plate 81a as the susceptor 81 is moved with respect to the
rotary pipe 77. With the aforesaid arrangement, the wafer W can be
held by the abutment portion 80a of the cathode ring 80 and the
wafer back side press plate 81a.
[0289] A rotative driving mechanism 45 for rotating the rotary pipe
77 about its axis is coupled to the rotary pipe 77. The rotative
driving mechanism 45 includes a second motor 45a provided on the
inversion base 181 and having a rotation shaft parallel to the axis
of the rotary pipe 77, a toothed pulley 45b fixed to the rotation
shaft of the second motor 45a, a toothed pulley 45c provided around
the rotary pipe 77, and a timing belt 45d stretched between the
toothed pulley 45b and the toothed pulley 45c for transmitting a
rotation force of the second motor 45a. The toothed pulleys 45b,
45c and the timing belt 45d are housed in a cover 181c (not shown
in FIG. 9) attached to the inversion base 181.
[0290] The rotary pipe 77 can be rotated about its axis (in a
direction indicated by an arrow c in FIG. 9) by a rotative driving
force of the second motor 45a. The second motor 45a may be, for
example, a servo motor. The rotation of the rotary pipe 77 is
transmitted to the support shaft 81b through the ball spline 190,
so that the rotary pipe 77 and the susceptor 81 are rotated
together. Thus, the wafer W held by the abutment portion 80a of the
cathode ring 80 and the wafer back side press plate 81a can be
rotated.
[0291] In the plating process, the wafer holding/rotating mechanism
74a to 74d is moved down by the lift mechanism 44 with the wafer W
thus held as facing downward, and a lower surface of the wafer W is
brought into contact with the plating liquid filled in the plating
vessel 61a to 61d.
[0292] A rotary joint 191 is attached to the end of the support
shaft 81b opposite from the wafer back side press plate 81a. One
end of a supply pipe 203 and one end of a leak pipe 204 are
connected to the rotary joint 191. The other end of the supply pipe
203 is branched into a cathode cleaning liquid pipe 201 and a
nitrogen gas pipe 202.
[0293] The cathode cleaning liquid pipe 201 is connected to a
cathode cleaning liquid supply source, and the nitrogen gas pipe
202 is connected to a nitrogen gas supply source. A valve 201V is
provided in the cathode cleaning liquid pipe 201, so that a cathode
cleaning liquid can be supplied into the rotary joint 191 by
opening the valve 201V. The cathode cleaning liquid may be, for
example, deionized water. In this case, the cathode cleaning liquid
(deionized water) can be supplied in to the cathode cleaning liquid
pipe 201 through the deionized water pipe 32 (see FIG. 3) which is
introduced into the enclosure 30 through the deionized water supply
pipe introduction port 32h of the enclosure 30.
[0294] A valve 202V is provided in the nitrogen gas pipe 202, so
that nitrogen gas can be supplied into the rotary joint 191 by
opening the valve 202V.
[0295] A single fluid channel 81c extends-through the support shaft
81b along the center axis of the support shaft 81b. A plurality of
fluid channels 81d are provided in the wafer back side press plate
81a in communication with the fluid channel 81c as extending from
the center to the peripheral edge of the wafer back side press
plate 81a. The fluid channels 81d open in the peripheral edge of
the wafer back side press plate 81a.
[0296] Even during the rotation of the susceptor 81, a treatment
fluid such as the cathode cleaning liquid or nitrogen gas can be
supplied into the fluid channels 81c, 81d from the cathode cleaning
liquid supply source or the nitrogen gas supply source on the side
of a stationary system through the rotary joint 191.
[0297] A part of the cathode a cleaning liquid supplied from the
supply pipe 203 is drained through the leak pipe 204. Thus,
particles generated by slidable members in the rotary joint 191 are
washed away into the leak pipe 204 by the cathode cleaning liquid
so as to be prevented from flowing into the fluid channels 81c,
81d.
[0298] FIG. 11 is a schematic sectional view of the rotary joint
191. The rotary joint 191 includes a stator 243 connected to the
supply pipe 203 and the leak pipe 204, and a rotor 244 connected to
the support shaft 81b of the susceptor 81.
[0299] The stator 243 includes a body 247, an inner cylinder 245
projecting from the body 247, and an outer cylinder 246 provided
around the inner cylinder 245 coaxially with the inner cylinder 245
and projecting from the body 247. The body 247, the inner cylinder
245 and the outer cylinder 246 are integrally formed. A joint 248
connected to the supply pipe 203 and a joint 249 connected to the
leak pipe 204 are attached to the body 247 as extending
perpendicularly to the lengths of the inner cylinder 245 and the
outer cylinder 246. A treatment fluid supply port 256 and a leak
port 257 extend from the joint 248 and the joint 249, respectively,
inwardly of the body 247.
[0300] The rotor 244 includes a joint 251 for connection to the
support shaft 81b, and a cylindrical member 250 as extending
coaxially with the support shaft 81b connected to the joint 251.
The rotor 244 has a through-hole 262 extending along the center
axis thereof. The joint 251 includes a connection pipe 258 having
an outer thread portion and a flange 260. The support shaft 81b has
an inner thread portion provided on an end interior surface thereof
and engaged with the outer thread portion of the connection pipe
258. The end of the support shaft 81b engaged with the connection
pipe 258 is restricted in position by the flange 260. A fluororesin
packing 261 is provided between the support shaft 81b and the
flange 260.
[0301] The cylindrical member 250 is fitted in an annular space
defined between the inner cylinder 245 and the outer cylinder 246
of the body 247 coaxially with the inner cylinder 245 and the outer
cylinder 246. The treatment fluid supply port 256, an inner space
245a of the inner cylinder 245 and the through-hole 262 of the
rotor 244 communicate with each other, and constitute a main
channel 270 for introducing the treatment fluid (the cathode
cleaning liquid or nitrogen gas) supplied from the supply pipe 203
into the fluid channel 81c provided in the support shaft 81b.
[0302] A first gap 252 is defined between the inner cylinder 245
and the cylindrical member 250, while a second gap 253 is defined
between the outer cylinder 246 and the cylindrical member 250. The
width of the first gap 252 (a distance between the inner cylinder
245 and the cylindrical potion 250) is, for example, 0.1 mm, but is
increased in the vicinity of a distal end of the cylindrical member
250. The width of the second gap 253 (a distance between the outer
cylinder 246 and the cylindrical member 250) is several
millimeters.
[0303] The main channel 270 and the first gap 252 communicate with
each other through a first communication portion 254 provided in
the vicinity of a distal end of the inner cylinder 245, while the
first gap 252 and the second gap 253 communicate with each other
through a second communication portion 255 provided in the vicinity
of the distal end of the cylindrical member 250. The leak port 257
communicates with a part of the second communication portion 255.
The first gap 252, the part of the second gap 253 and the leak port
257 constitute a leak channel 271, and the main channel 270 and the
leak pipe 204 communicate with each other through the leak channel
271.
[0304] A first spacer 263, a sealing ring 264, a second spacer 265,
a C-ring 266, two bearings 267 and a third spacer 268 are disposed
in the second gap 253 in this order from the side of the second
communication portion 255. These components except the C-ring 266
each have a closed ring shape and surround the cylindrical member
250. The sealing ring 264 is held between the first spacer 263 and
the second spacer 265 thereby to be located at a fixed position
axially of the outer cylinder 246.
[0305] The first spacer 263 and the second spacer 265 contact the
outer cylinder 246, but do not contact the cylindrical member 250.
The bearings 267 are located at fixed positions axially of the
cylindrical member 250, and support the cylindrical member 250 and
the outer cylinder 246 in a rotatable manner. The C-ring 266 is
fitted in a shallow groove provided in a predetermined position of
the cylindrical member 250.
[0306] The sealing ring 264 includes a fluororesin press-fit member
(lip portion) 264a having a U-shaped cross section opening toward
the second communication potion 255, a coil spring (helical spring)
264b provided in the press-fit member 264a, and a press member 264c
partly covering an open portion of the press-fit member 264a. The
press-fit member 264a is urged outward from the center of the coil
spring 264b by the resilient force of the coil spring 264b, and
kept in contact with the outer cylinder 246 and the cylindrical
member 250. The coil spring 264b is composed of a material
resistant to the cathode cleaning liquid to be used. The press
member 264c presses the coil spring 264b to prevent the coil spring
264b from disengaging from the press-fit member 264a.
[0307] The outer cylinder 246 has an outer thread portion provided
on an outer surface portion adjacent to the distal end thereof. A
fixture ring 269 having an inner thread portion in association with
the outer thread portion is fitted around the outer cylinder 246.
The fixture ring 269 includes a flange 269a provided at an end
thereof adjacent to the rotor 244 as projecting inwardly thereof.
The flange 269a extends between the third spacer 268 and the flange
260.
[0308] When the rotary joint 191 is assembled by combining the
stator 243 with the rotor 244, the fixture ring 269 is threadingly
engaged around the outer cylinder 246, whereby the third spacer 268
can be squeezed toward the second gap 253 (toward the second
communication portion 255) by the flange 269a. Thus, the C-ring
266, the bearings 267 and the third spacer 268 can be introduced
into the predetermined axial positions.
[0309] An end of the leak pipe 204 opposite from the rotary joint
191 usually opens at the atmospheric pressure, while the treatment
fluid flowing through the main channel 270 is generally
pressurized. Therefore, the treatment fluid flowing through the
main channel 270 partly flows into the leak channel 271 which has a
lower internal pressure. The treatment fluid (particularly, the
cathode cleaning liquid) flowing through the leak channel 271
partly flows through the second communication portion 255 to reach
the second gap 253, but the flow thereof is prevented by the
sealing ring 264. Therefore, there is no possibility that the
treatment fluid leaks toward the bearings 267.
[0310] When the support shaft 81b is rotated, the rotor 244 is also
rotated. The rotor 244 is supported with respect to the stator 243
via the sealing ring 264 and the bearings 267 and, hence, can
freely be rotated with respect to the stator 243. By the rotation
of the rotor 244, the press-fit member 264a is brought into
friction with either or both of the outer cylinder 246 and the
cylindrical member 250. Although the fluororesin press-fit member
264a has a sufficient wear resistance, a small amount of particles
are generated.
[0311] Since the treatment fluid flows from the first gap 252
toward the leak port 257 in the leak channel 271, the particles
generated around the sealing ring 264 are drained together with the
treatment fluid (particularly, the cathode cleaning liquid) into
the leak pipe 204 through the leak channel 271. Therefore, there is
no possibility that the treatment fluid flowing through the main
channel 270 is contaminated with the particles.
[0312] An ejector may be attached to the end of the leak pipe 204
opposite from the rotary joint 191. In this case, when the flow
rate of the treatment fluid flowing into the leak channel 271 from
the main channel 270 is low, a pressure on the side of the leak
port 257 is reduced to a negative level by the ejector for forcibly
increasing the flow rate of the treatment fluid. Even if the
internal pressure of the main channel 270 is close to the
atmospheric pressure, the flow rate of the treatment fluid flowing
through the leak channel 271 can be increased.
[0313] Thus, the flow rate of the treatment fluid flowing through
the leak channel 271 can be adjusted by adjusting the pressure on
the side of the leak port 257, suppressing the movement of the
particles generated around the sealing ring 264 toward the main
channel 270. The flow of the particles toward the main channel 270
can further be suppressed by reducing the width of the first gap
252 to 50 .mu.m.
[0314] Where the first gap 252 has a reduced width, the treatment
fluid present in the first gap 252 experiences a great pressure
loss. Therefore, even if the treatment fluid flowing through the
main channel 270 is highly pressurized to increase the flow rate of
the treatment fluid in the main channel 270, a great pressure (or
load) is not exerted on the sealing ring 264. Therefore, the
service life of the sealing ring 264 is prolonged. Where the
treatment fluid is the cathode cleaning liquid, the cathode
cleaning liquid present in the second gap 253 serves to lubricate
and cool the sealing ring 264. This also prolongs the service life
of the sealing ring 264.
[0315] The particles can be washed away by a small amount of the
treatment fluid flowing through the leak channel 271. By reducing
the width of the first gap 252, the amount of the treatment fluid
flowing through the first gap 252 can be reduced, thereby reducing
the consumption of the treatment fluid such as the cathode cleaning
liquid.
[0316] Since the inner cylinder 245 and the outer cylinder 246 are
formed integrally with the body 247, the inner cylinder 245 and the
outer cylinder 246 are spaced exactly the predetermined distance.
Further, the cylindrical member 250 is supported with respect to
the outer cylinder 246 at three positions by the sealing ring 264
and the two bearings 267, so that the distance between the
cylindrical member 250 and the outer cylinder 246, i.e., the width
of the second gap 253, can be kept exactly at the predetermined
level. Therefore, the distance between the cylindrical member 250
and the inner cylinder 245, i.e., the width of the first gap 252,
is also kept at the predetermined level. Hence, there is no
possibility that the cylindrical member 250 is brought into contact
with the inner cylinder 245.
[0317] A plurality of leak channels 271 and a plurality of leak
ports 257 may be provided.
[0318] FIG. 12 is a schematic sectional view illustrating a portion
around the wafer as observed in the plating process. FIG. 13(a) is
a schematic plan view illustrating the entire cathode ring 80 (as
viewed from the side of the spin base 78), and FIG. 13(b) is a
schematic sectional view of the cathode ring 80. FIG. 13(c) is a
schematic plan view illustrating an inner peripheral portion of the
cathode ring 80 on a greater scale.
[0319] With reference to FIGS. 12 and 13(a) to 13(c), an
explanation will be given to the construction of the cathode ring
80. The cathode ring 80 includes an upper ring 80u, a conduction
plate 80c and a base ring 80b arranged in this order from the side
of the spin base 78. The upper ring 80u, the conduction plate 80c
and the base ring 80b each have an annular shape. The base ring 80b
is composed of a rigid material. The conduction plate 80c is
covered with the upper ring 80u and the base ring 80b. The upper
ring 80u and the base ring 80b are opposed (adjacent) to each other
along the outer periphery of the conduction plate 80c and along the
inner periphery of the conduction plate 80c opposite from the spin
base 78.
[0320] The conduction plate 80c is electrically conductive. The
conduction plate 80c has a higher strength than the upper ring 80u
and the base ring 80b to impart the entire cathode ring 80 with a
sufficient strength.
[0321] The base ring 80b is provided with the abutment portion 80a
which is composed of a rigid material. Examples of the rigid
material include rigid vinyl chloride resins, rigid fluororesins
and polyimide resins. The abutment portion 80a has a sealing
surface 80s to be brought into contact with the wafer W in opposed
relation to the wafer back side press plate 81a. The sealing
surface 80s is a polished surface. Since the base ring 80b is
provided with the abutment portion 80a, the base ring 80b has a
slightly smaller inner diameter than the upper ring 80u.
[0322] An annular projection 81e slightly projecting toward the
abutment portion 80a is provided on a peripheral portion of the
wafer back side press plate 81a opposed to the abutment portion
80a. The projection 81e is composed of a soft material. For
example, the projection 81e may be an O-ring of a silicone rubber
or a coil spring coated with a fluororesin. In the plating process,
the wafer W is generally horizontally held between the projection
81e and the abutment portion 80a as shown in FIG. 12.
[0323] In this state, a surface 80g of the abutment portion 80a
opposed to the plating vessel 61a to 61d (opposite from the sealing
surface 80s) is inclined downward outwardly from the center of the
cathode ring 80. That is, the abutment portion 80a projects as
tapered inwardly from the body of the cathode ring 80, so that a
force can be exerted on the wafer W toward the center axis of the
cathode ring 80 which is perpendicular to the projecting direction
of the abutment portion 80a. Since the base ring 80b including the
abutment portion 80a is composed of the rigid material, this
structure can be realized.
[0324] Thus, the total size of the abutment portion 80a and its
periphery can be reduced, whereby the inner diameter of the
abutment portion 80a can correspondingly be increased. Therefore,
the effective plating area, i.e., the area of the wafer W in
contact with the plating liquid, can be increased.
[0325] The base ring 80b has a plurality of through-holes extending
radially therethrough. These through-holes communicate with a gap
defined between the upper ring 80u and the base ring 80b along the
inner periphery of the cathode ring 80, and constitute fluid
channels 80f which extend in generally coplanar relation. The fluid
channels 80f open toward the center of the cathode ring 80.
[0326] Where the wafer back side press plate 81a and the cathode
ring 80 are located in position in the plating process, the fluid
channels 80f are located at a lower position than the fluid
channels 81d. A multiplicity of notches 80k (see FIG. 13(c)) are
provided in an inner peripheral portion of the upper ring 80u,
whereby the cathode cleaning liquid flowing out of the fluid
channels 81d opening in the periphery of the wafer back side press
plate 81a can be introduced into the fluid channels 80f in the
plating process.
[0327] A cathode 83 is disposed in the fluid channels 80f (in the
gap between the upper ring 80u and the base ring 80b). Therefore,
the cathode 83 can be cleaned with the cathode cleaning liquid in
the plating process. The cathode 83 is disposed within
substantially the same plane as the sealing surface 80s outwardly
of the abutment portion 80a with respect to the center of the
cathode ring 80.
[0328] FIG. 14(a) is a schematic plan view illustrating the shape
of the cathode 83, and FIG. 14(b) is a diagram illustrating a part
of the cathode 83 on a greater scale. FIG. 14(c) is a schematic
sectional view of the cathode 83.
[0329] The cathode 83 is composed of a spring stainless steel
having a thickness of about 0.1 mm, and has a surface plated with
platinum. This prevents formation of an oxide film on the surface
of the cathode 83, and prevents dissolution of the cathode 83 even
if a reverse electric field is applied to the cathode 83. The
platinum film of the cathode 83, if having a very small thickness,
has a shorter service life. The cathode 83 behaves resiliently in
contact with wafer W. However, if the platinum film of the cathode
83 is too thick, the film is liable to be cracked in the resilient
behavior. In view of these, the thickness of the platinum film of
the cathode 83 is preferably about 0.01 .mu.m to about 2 .mu.m.
[0330] The cathode 83 has a ring portion 83r having a slightly
greater inner diameter than the upper ring 80u, and a multiplicity
of contact portions 83c generally equidistantly arranged like a
comb circumferentially of the ring portion 83r as extending from
the ring portion 83r toward the center of the ring portion 83r. The
contact portions 83c are each bent at an angle .theta. of 5 to 60
degrees with their distal ends raised from the cathode ring 80
toward the wafer back side press plate 81a (see FIG. 12).
[0331] With the cathode 83 attached to the cathode ring 80, the
distal ends of the contact portions 83c project from the gap
between the upper ring 80u and the base ring 80b toward the inner
periphery of the upper ring 80u (see FIGS. 12 and 13(c)). The angle
of the bent contact portions 83c is restricted by the upper ring
80u (see FIG. 12).
[0332] Referring to FIG. 12, the abutment portion 80a is brought
into contact with a portion of one surface of the wafer W slightly
inward from the peripheral edge of the wafer W in the plating
process. The cathode 83 is brought into resilient contact with a
peripheral edge portion of the surface of the wafer W contacting
the abutment portion 80a, while the wafer W is held between the
abutment portion 80a and the wafer back side press plate 81a. That
is, the contact portions 83c can be kept in contact with the wafer
W at a predetermined contact pressure.
[0333] An electrically-conductive electrode press 80d having a ring
shape coaxial with the cathode ring 80 is disposed between the base
ring 80b and the upper ring 80u on a side of the conduction plate
80c opposite from the spin base 78. The electrode press 80d has a
groove formed circumferentially thereof, and a coil spring 80e
having a ring shape coaxial with the electrode press 80d is housed
in the groove.
[0334] The cathode 83 is fixed to the electrode press 80d for
electrical connection, and the electrode press 80d and the
conduction plate 80c are kept in resilient contact with each other
by the coil spring 80e for electrical connection. Thus, the
electrical connection is maintained between the electrode press 80d
and the conduction plate 80c, even if the base ring 80b is pressed
by the wafer back side press plate 81a to be warped or slightly
offset from the upper ring 80u. This ensures proper plating of
wafer W.
[0335] The support posts 79 are electrically conductive, and extend
through the upper ring 80u so as to be electrically connected to
the conduction plate 80c. The support posts 79 are not provided
equidistantly circumferentially of the cathode ring 80, but
provided in two pairs which are spaced at about 180 degrees around
the center of the cathode ring 80 (see FIG. 13(a)). Thus, the wafer
W can easily be inserted between the wafer back side press plate
81a and the cathode ring 80 through a space defined between the
support posts 79 arranged at a wider interval.
[0336] O-rings 80r are provided between the support posts 79 and
the upper ring 80u (around the support posts 79), between the upper
ring 80u and the base ring 80b around the conduction plate 80c,
between the upper ring 80u and the electrode press 80d (along the
inner periphery of the electrode press 80d), and between the base
ring 80b and the electrode press 80d (along the outer periphery of
the electrode press 80d). This prevents the plating liquid from
intruding into the cathode ring 80 (the base ring 80b and the upper
ring 80u). Thus, the inside of the cathode ring 80 can be kept
clean.
[0337] Electrically conductive coupling members 79j are attached to
ends of the support posts 79 opposite from the conduction plate
80c. The coupling members 79j each couple two adjacent support
posts 79 (see FIG. 13(a)). The coupling members 79j are each formed
with a positioning hole 79h.
[0338] A conduction line 198 is provided within the spin base 78
and the rotary pipe 77. The conduction line 198 may be, for
example, a coated conduction cable, which is electrically isolated
from the spin base 78 and the rotary pipe 77. Electrically
conductive coupling members 78j are each attached to the peripheral
portion of the surface of the spin base 78 facing toward the
cathode ring 80 via an insulative plate 78i. The coupling members
78j each have a positioning pin 78p provided in association with
the positioning hole 79h of the coupling member 79j. The conduction
line 198 is electrically connected to the coupling member 78j via a
conduction stud 78s extending through the insulative plate 78i. The
coupling members 78j are respectively coupled to the coupling
members 79j.
[0339] With the aforesaid arrangement, the cathode 83 is
electrically connected to the conduction line 198. Even if the spin
base 78 and the rotary pipe 77 are composed of a metal, an electric
current flowing through a conduction path between a plating power
source 82 and the cathode 83 is prevented from flowing through the
spin base 78 and the rotary pipe 77 by the insulative plates
78i.
[0340] The coupling members 78j are respectively coupled to the
coupling members 79j with the positioning pins 78p fitted in the
positioning holes 79h. Thus, the cathode ring 80 is fixed to the
spin base 78 in predetermined positional relation. In this state,
the center axis of the cathode ring 80 and the center axis
(rotation axis) of the spin base 78 are generally aligned with each
other, so that the cathode ring 80 can properly be rotated together
with the spin base 78. Even when the cathode ring 80 and the spin
base 78 are rotated at a high speed, there is no possibility that
the cathode ring 80 is offset from the spin base 78.
[0341] The cathode ring 80 can be detached from the spin base 78
for cleaning thereof by decoupling the coupling members 78j and 79j
from each other. At this time, the cathode ring 80 can be cleaned
by immersing the cathode ring 80 in the cleaning liquid without the
need for disassembling the cathode ring 80, because the O-rings 80r
prevents the cleaning liquid from intruding into the cathode ring
80. When the cathode ring 80 is detached from the spin base 78, the
support posts 79 serve as handles of the cathode ring 80.
[0342] When the cathode ring 80 is attached to the spin base 78,
the coupling members 78j and 79j are coupled to each other with the
positioning pins 78p inserted into the positioning holes 79h,
whereby the cathode ring 80 can easily be fixed to the spin base 78
in predetermined positional relation.
[0343] Referring to FIGS. 9 and 10, an electrical connection
mechanism 192 is provided between the plating power source 82 and
the conduction line 198, so that electrical connection can be
established between the conduction line 198 rotated together with
the cathode ring 80 and the plating power source 82 on the side of
the stationary system.
[0344] The electrical connection mechanism 192 includes an
electrically conductive pulley 193 fitted around an end portion of
the rotary pipe 77 opposite from the spin base 78, an electrically
conductive rotary shaft 194 rotatably attached to the inversion
base 181 in parallel relation to the rotary pipe 77, an
electrically conductive pulley 195 fitted around the rotary shaft
194, an electrically conductive belt 196 stretched between the
pulley 193 and the pulley 195, and a rotary connector 197 attached
to a distal end of the rotary shaft 194.
[0345] An end of the rotary shaft 194 opposite from the rotary
connector 197 is rotatably supported by a bearing box 200 attached
onto the inversion base 181. The end of the rotary shaft 194
adjacent to the bearing box 200 is isolated from the surroundings
by the bearing box 200.
[0346] The pulley 193 is isolated from the rotary pipe 77. The
pulleys 193, 195 each have a surface plated with gold, for example,
which is kept in contact with the belt 196. The belt 196 may be a
steel belt having a surface plated with gold, for example. In this
case, the electrical resistance between the pulley 193 and the
pulley 195 can be reduced.
[0347] The pulley 193 and the pulley 195 are mechanically connected
to each other by the belt 196. When the rotary pipe 77 is rotated
by the rotative driving mechanism 45, the rotative driving force is
transmitted to the rotary shaft 194 via the pulley 193, the belt
196 and the pulley 195, whereby the rotary shaft 194 is rotated.
Even during the rotation of the rotary pipe 77 and the rotary shaft
194, the electrical connection between the pulleys 193 and 195 is
maintained through the belt 196.
[0348] The rotary connector 197 is capable of electrically
connecting the stationary system to the rotary system, and has a
stationary terminal 197a and a rotary terminal 197b. The rotary
connector 197 is of a non-slidable type, which has no sliding
contact between the solid components, but establishes the
electrical connection between the stationary terminal 197a and the
rotary terminal 197b, for example, by mercury (Hg). Therefore, the
electrical connection between the terminals 197a and 197b is stable
with a reduced noise. In addition, the rotary connector 197 has a
longer service life.
[0349] The conduction line 198 (see FIG. 12) is electrically
connected to the pulley 193. The pulley 193 is electrically
isolated from the rotary pipe 77. Further, the pulley 195 is
electrically connected to the rotary shaft 194. The rotary shaft
194 is electrically connected to the rotary terminal 197b of the
rotary connector 197. The stationary terminal 197a of the rotary
connector 197 is electrically connected to the plating power source
82 via a conduction line 199A.
[0350] With the aforesaid arrangement, a conduction path between
the cathode 83 and the plating power source 82 is established via
the electrode press 80d, the coil spring 80e, the conduction plate
80c, the support posts 79, the coupling members 79j, 78j, the
conduction studs 78s, the conduction line 198, the pulley 193, the
belt 196, the pulley 195, the rotary shaft 194, the rotary
connector 197 and the conduction line 199A. Thus, the to-be-treated
surface of the wafer W held between the cathode ring 80 and the
wafer back side press plate 81a can electrically be energized.
[0351] Even when the wafer W is rotated by the rotative driving
mechanism 45, the electrical connection between the cathode 83 and
the plating power source 82 is maintained by the electrical
connection mechanism 192. Where the belt 196 is stretched between
the pulleys 193 and 195 with a sufficiently great tensile force,
the belt 196 can be brought into non-sliding contact with the
pulleys 193 and 195. Since the rotary connector 197 is of a
non-slidable type, there is no sliding contact in the conduction
path between the plating power source 82 and the cathode 83.
Therefore, the electrical connection can properly be established
between the plating power source 82 and the cathode 83, while a
noise attributable to the sliding contact such as a so-called brush
noise is suppressed.
[0352] Since the rotary joint 191 and the rotary connector 197 are
respectively attached to the ends of the support shaft 81b and the
rotary shaft 194, the replacement thereof is easy. That is, when
either of the rotary joint 191 and the rotary connector 197 is
detached or attached, interference between the rotary joint 191 and
the rotary connector 197 can be avoided, which may otherwise occur
where the rotary joint 191 and the rotary connector 197 are both
attached to the support shaft 81b or the rotary pipe 77.
[0353] Since the rotary joint 191 and the rotary connector 197 are
respectively attached to the ends of the support shaft 81b and the
rotary shaft 194, the lengths of the support shaft 81b (rotary pipe
77) and the rotary shaft 194 can be reduced. Therefore, the size of
the wafer holding/rotating mechanism 74a to 74d as measured axially
of the support shaft 81b can be reduced, so that the wafer
holding/rotating mechanism 74a to 74d can be inverted with a
reduced turning radius.
[0354] By properly setting the ratio of the diameter of the pulley
193 to the diameter of pulley 195, the rotary shaft 194 can be
rotated at a sufficiently low rotation speed even if the rotary
pipe 77 is rotated at a high speed. Thus, a load exerted on the
rotary connector 197 can be reduced to extend the service life of
the rotary connector 197.
[0355] Where the pulleys 193 and 195 are directly engaged with each
other without the belt 196, the same effects can be provided.
Further, where electrically conductive gears are employed instead
of the pulleys 193, 195 and meshed with each other, the same
effects can be provided.
[0356] The components which constitute the conduction path
extending from the cathode 83 to the plating power source 82 are
isolated from the other metal components, the metal screws and the
metal bearings, and assuredly isolated from the ground. This
prevents the electric current from flowing through unintended
portions, and prevents a noise from interfering with the electric
current flowing between the cathode 83 and the plating power source
82.
[0357] The operations of the plating power source 82, the inversion
driving section 43 (rotary actuator 183), the lift mechanism 44
(first motor 44c), the rotative driving mechanism 45 (second motor
45a) and the susceptor movement mechanism 46 (air cylinder 46a),
and the opening and closing of the valves 201V, 202V are controlled
by the system controller 155.
[0358] Next, an explanation will be given to the construction of
the plating cup 56a to 56d. Referring to FIGS. 9 and 12, the
plating vessel 61a to 61d includes a cylindrical side wall 361
having an inner diameter virtually equal to the outer diameter of
the wafer W. The upper edge of the plating vessel 61a to 61d is
present within substantially the same plane. A plating liquid
introduction port 54 is provided in a bottom center portion of the
plating vessel 61a to 61d. The branch liquid supply pipe 58a to 58d
is connected to the plating liquid introduction port 54 as slightly
projecting into the plating vessel 61a to 61d. A hemispherical
shower head 75 having a multiplicity of holes is attached to an end
of the branch liquid supply pipe 58a to 58d located in the plating
vessel 61a to 61d. The plating liquid is diffusively introduced in
various directions (at various angles) into the plating vessel 61a
to 61d through the shower head 75.
[0359] A plating liquid outlet port 53 is provided in the bottom of
the plating liquid recovery vessel 62a to 62d. The branch return
pipe 63a to 63d is connected in communication with the plating
liquid recovery vessel 62a to 62d via the plating liquid outlet
port 53.
[0360] A cathode cleaning liquid collection vessel 210 is provided
around the plating liquid recovery vessel 62a to 62d for collecting
the cathode cleaning liquid used for the cleaning of the cathode
83. That is, the plating cup 56a to 56d has a triple structure
having the plating vessel 61a to 61d, the plating liquid recovery
vessel 62a to 62d and the cathode cleaning liquid collection vessel
210 arranged in this order from the inside to the outside. Thus,
the cathode cleaning liquid and the plating liquid can separately
be collected.
[0361] A three-dimensional filter including a plurality of mesh
members 49 (about 3 to about 300 mesh members) of a fluororesin
(e.g., a tetrafluoroethylene polymer (TEFLON.RTM.)) stacked one on
another is provided in an upper portion of the plating vessel 61a
to 61d. For example, the mesh members 49 each have an open mesh
size of about 0.0.5 mm to about 5 mm. Contaminants in the plating
liquid can be removed by the mesh member 49.
[0362] The mesh members 49 each have a round plan shape having an
outer diameter virtually equal to the inner diameter of the plating
vessel 61a to 61d. The plurality of stacked mesh members 49
generally entirely cover the plating vessel 61a to 61d as viewed in
plan. The plating liquid supplied upward from the lower side of the
plating vessel 61a to 61d is rectified into a generally uniform
upward flow by the mesh members 49.
[0363] By stacking the mesh members 49, the effect of removing the
contaminants from the plating liquid and the effect of rectifying
the plating liquid can be enhanced.
[0364] A mesh anode 76 is provided at a level about one fourth the
depth of the plating vessel 61a to 61d from the bottom in the
plating vessel 61a to 61d (between the shower head 75 and the mesh
members 49). The anode 76 is a titanium mesh member coated with
iridium oxide, and is insoluble in the plating liquid. Since the
anode 76 is mesh-shaped, the flow of the plating liquid is not
hindered by the anode 76.
[0365] The anode 76 has a round plan shape having an outer diameter
virtually equal to the inner diameter of the plating vessel 61a to
61d, and generally entirely covers the plating vessel 61a to 61d as
viewed in plan. The anode 76 is connected to the plating power
source 82 via a conduction line 199B.
[0366] Components which constitute a conduction path extending from
the anode 76 to the plating power source 82 are isolated from the
other metal components, and assuredly isolated from the ground.
This prevents an electric current from flowing through unintended
portions, and prevents a noise from interfering with the electric
current flowing between the anode 76 and the plating power source
82.
[0367] FIG. 15 is a schematic diagram illustrating an electric
equivalent circuit in the plating vessel 61a to 61d. With reference
to FIG. 15, an explanation will be given to how the mesh members 49
influence the uniformity of the plating.
[0368] It is herein assumed that: the plating liquid has an
electrical resistance R.sub.L in a region of the plating vessel
between the anode 76 and the mesh members 49; the plating liquid
has an electrical resistance R.sub.P in a region of the plating
vessel where the vertically stacked mesh members 49a are disposed;
the seed layer formed on the to-be-treated surface of the wafer W
has an electrical resistance r.sub.s between the center and the
periphery thereof; and a voltage V is applied between the cathode
83 and the anode 76.
[0369] Provided that the amperage of the electric current flowing
vertically from the center of the anode 76 to the center of the
wafer W is i.sub.c and the amperage of the electric current flowing
vertically from the peripheral portion of the anode 76 to the
peripheral portion of the wafer W is i.sub.E, the voltage V is
represented by an expression
V=i.sub.E(R.sub.L+R.sub.P)=i.sub.c(R.sub.L+R.sub.P+r.sub.s) That
is, the amperage i.sub.E of the electric current flowing vertically
from the peripheral portion of the anode 76 to the peripheral
portion of the wafer W is smaller than the amperage i.sub.c of the
electric current flowing vertically from the center of the anode 76
to the center of the wafer W.
[0370] In the region where the mesh members 49 are disposed, the
electric current flows only through the plating liquid which fills
voids of the mesh members 49, because the mesh members 49 are
composed of an insulative material. Therefore, the plating liquid
in the region where the mesh members 49 are present has a higher
electrical resistance than the plating liquid in the region where
the mesh members 49 are absent. Where the volume ratio of the solid
component (mesh members 49) in the region where the mesh members 49
are present is 50%, for example, the electrical resistance R.sub.P
is about twice greater. Accordingly, the electrical resistance
r.sub.s of the seed layer between the center and the periphery of
the seed layer is smaller than the electrical resistance
R.sub.L+R.sub.P of the plating liquid in the entire plating vessel
including the region where the mesh members 49 are present
(r.sub.s<<R.sub.L+R.sub.P).
[0371] Therefore, there is only a small difference between the
amperage i.sub.c of the electric current flowing vertically from
the center of the anode 76 to the center of the wafer W and the
amperage i.sub.E of the electric current flowing vertically from
the peripheral portion of the anode 76 to the peripheral portion of
the wafer W (i.sub.E.apprxeq.i.sub.c). Since a film growth rate in
the plating process is proportional to the amperage of the electric
current flowing across the interface between the plating liquid and
the wafer W, a difference in the thickness of the film formed by
the plating between the center and the peripheral portion of the
wafer W is reduced. That is, the uniformity of the thickness of the
film formed by the plating is improved by providing the mesh
members 49 in the plating liquid. The uniformity of the film
thickness is improved as the electrical resistance of the
conduction path is increased by the provision of the mesh members
49.
[0372] Referring to FIG. 12, an upper edge portion of the plating
vessel 61a to 61d has a reduced wall thickness with its outer
circumferential portion cut away. The upper edge of the plating
vessel 61a to 61d has a surface 60i inclined downward outwardly
from the center of the plating vessel 61a to 61d. The inclined
surface 61i is brought into opposed parallel relation to the
inclined surface 80g of the abutment portion 80a of the cathode
ring 80. The outer circumferential portion of the plating vessel
61a to 61d adjacent to the upper edge is concavely curved for
prevention of interference with the projection 80p of the cathode
ring 80.
[0373] Thus, the upper edge portion of the plating vessel 61a to
61d is complementary in configuration to the portion of the cathode
ring 80 (base ring 80b) to be brought into opposed relation to the
plating vessel 61a to 61d. This prevents the interference between
the plating vessel 61a to 61d and the cathode ring 80 in the
plating process, while permitting the wafer W to approach the
plating vessel 61a to 61d until the lower surface of the wafer W
and the upper edge of the plating vessel 61a to 61d are located at
substantially the same level. That is, a distance between the upper
edge of the plating vessel 61a to 61d and the wafer W can
arbitrarily be adjusted within a predetermined range from 0 mm.
[0374] Since the abutment portion 80a is tapered inwardly of the
cathode ring 80, an angle formed between the lower surface of the
wafer W and the inclined surface 80g is obtuse. Thus, the plating
liquid can flow out of the plating vessel 61a to 61d without
stagnation around the abutment portion 80a. This permits the
plating liquid to flow from the center to the periphery of the
wafer W over the entire lower surface of the wafer W, thereby
improving the uniformity of the plating.
[0375] Where the abutment portion 80a is not composed of a rigid
material, it is necessary to provide a member (hereinafter referred
to as "abutment portion support member") for supporting the
abutment portion 80a from a lower side (opposite from the sealing
surface 80s). In this case, the abutment portion support member
interferes with the upper edge of the plating vessel 61a to 61d, so
that the wafer W is merely permitted to reach a predetermined
distance short of the upper edge of the plating vessel 61a to 61d.
Therefore, the plating liquid cannot flow in the aforesaid manner,
making the uniform plating impossible.
[0376] Further, the plating liquid stagnates around the abutment
portion support member in the plating process. The plating liquid
is liable to remain around the abutment portion support member to
contaminate the wafer W after the completion of the plating
process. In this embodiment, however, these problems are eliminated
because the abutment portion 80a and the base ring 80b are composed
of the rigid material.
[0377] The projection 80p of the cathode ring 80 is inserted in an
upper portion of the recovery vessel 62a to 62d in the plating
process.
[0378] With the wafer W in contact with the plating liquid, the
distance between the wafer W and the mesh members 49 is adjusted
within a range between 0.5 mm and 30 mm (preferably, 0.5 mm and 20
mm) in consideration of the flow of the plating liquid. More
specifically, where the distance between the wafer W and the mesh
members 49 is reduced as described above, the plating liquid is
drawn by the rotating wafer W only in a limited region. This
suppresses the eddy flow of the plating liquid which is unwanted
for the plating. Thus, the film formed by the plating has a uniform
thickness.
[0379] FIG. 16 is a schematic plan view of the plating cup 56a to
56d. Referring to FIGS. 9 and 16, the cathode cleaning liquid
collection vessel 210 has a generally square shape as seen in plan.
A deionized water supply nozzle 205 for supplying deionized water
to the cathode cleaning liquid collection vessel 210 and a liquid
trap 211 for trapping the liquid in the cathode cleaning liquid
collection vessel 210 are provided in one pair of opposed corner
portions in the cathode cleaning liquid collection vessel 210. The
cathode cleaning liquid collected in the cathode cleaning liquid
collection vessel 210 through the fluid channels 80f formed in the
cathode ring 80 (see FIG. 12) is washed away into the liquid trap
211 by the deionized water supplied from the deionized water supply
nozzle 205.
[0380] The deionized water supply nozzle 205 may be obviated, so
that only the cathode cleaning liquid flows through the cathode
cleaning liquid collection vessel 210 into the liquid trap 211.
[0381] Air outlet pipes 215 are provided in the other pair of
opposed corner portions (provided with neither the deionized water
supply nozzle 205 nor the liquid trap 211) in the cathode cleaning
liquid collection vessel 210 in communication with the cathode
cleaning liquid collection vessel 210.
[0382] FIG. 17 is a schematic sectional view illustrating a portion
around the deionized water supply nozzle 205. The deionized water
supply nozzle 205 is provided upright on the bottom 210a of the
cathode cleaning liquid collection vessel 210, and has two openings
205a, 205b laterally opening at a predetermined height from the
bottom 210a. The openings 205a, 205b open in opposite
directions.
[0383] A deionized water pipe 206 is attached to the bottom 210a in
communication with the deionized water supply nozzle 205 so as to
supply deionized water to the deionized water supply nozzle 205.
The deionized water is discharged from the openings 205a, 205b of
the deionized water supply nozzle 205 toward the two air outlet
pipes 215 (see FIG. 16).
[0384] FIG. 18 is a schematic sectional view illustrating a portion
around the liquid trap 211. The liquid trap 211 is attached to a
lower side of the bottom 210a. A liquid drain port 210b is provided
in the bottom 210a, and an annular projection 207 having a small
height is provided around the liquid drain port 210b on an upper
side of the bottom 210a. The liquid in the cathode cleaning liquid
collection vessel 210 flows into the liquid trap 211 through the
liquid drain port 210b when the liquid surface is higher than the
annular projection 207.
[0385] A conductivity meter 212 is inserted in the liquid trap 211.
Thus, the electrical conductivity of the liquid trapped in the
liquid trap 211 can be measured. An output signal of the
conductivity meter 212 is inputted to the system controller 155
(see FIG. 9).
[0386] An overflow pipe 213 extends from an upper edge portion of a
side wall of the liquid trap 211, and a drain pipe 214 extends from
the bottom of the liquid trap 211. During the plating process, the
flow channel of the drain pipe 214 is closed, so that the liquid
(the cathode cleaning liquid and the like) flowing into the cathode
cleaning liquid collection vessel 210 fills the liquid trap 211 and
overflows through the overflow pipe 213. When the plating unit 20a
to 20d is not in use, the flow channel of the drain pipe 214 is
opened to drain the liquid from the liquid trap 211.
[0387] An outer vessel 208 is attached to the lower side of the
bottom 210a. The liquid trap 211 and parts of the overflow pipe 213
and the drain pipe 214 adjacent to junctions with the liquid trap
211 are accommodated in the outer vessel 208.
[0388] FIG. 19 is a schematic sectional view illustrating a portion
around a junction between the air outlet pipe 215 and the cathode
cleaning liquid collection vessel 210. The air outlet pipe 215 is
introduced into the cathode cleaning liquid collection vessel 210
through the bottom 210a. A hood 209 is attached to an end of the
air outlet pipe 215. The hood 209 has an opening formed in an upper
portion of a side wall thereof, but covers an upper side of an open
end of the air outlet pipe 215. Thus, the liquid such as the
cathode cleaning liquid is less liable to enter the air outlet pipe
215.
[0389] Gas can be exhausted from the plating cup 56a to 56d through
the air outlet pipes 215. Thus, air possibly exposed to the plating
liquid in the plating cup 56a to 56d can be exhausted to the
outside through the cathode cleaning liquid collection vessel 210
and the air outlet pipes 215.
[0390] Next, an explanation will be given to the plating process to
be performed by the plating section 12. Referring to FIG. 9, the
system controller 155 first controls the inversion driving section
43 to invert any of the wafer holding/rotating mechanisms 74a to
74d (herein assumed to be the wafer holding/rotating mechanism 74a)
with the wafer back side press plate 81a thereof facing upward.
Further, the system controller 155 controls the susceptor movement
mechanism 46 to move the wafer back side press plate 81a toward the
rotary pipe 77, so that the wafer transfer pins 84 project out
through the wafer back side press plate 81a. This state is shown in
FIG. 20.
[0391] The rotation angular position of the spin base 78 is
adjusted so that a circumferential portion of the spin base 78
having a wider support post interval (see FIG. 13(a)) is positioned
in opposed relation to the second transport path 15. The spin base
78 is kept at the rotation angular position by a retention torque
of the second motor 45a.
[0392] On the other hand, an untreated wafer W is taken out of the
cassette C by means of the retractable arm 41 or the retractable
arm 42 of the transport robot TR (see FIGS. 5(a) to 5(c)). The
wafer W is loaded onto the wafer transfer pins 84 through the space
between the support posts 79 by the transport robot TR with the
center of the wafer W coinciding with the center axis of the rotary
pipe 77 (see FIG. 13(a)). In this state, the to-be-treated surface
of the wafer W faces upward.
[0393] Then, the system controller 155 controls the susceptor
movement mechanism 46 to move the wafer back side press plate 81a
upward apart from the rotary pipe 77. Thus, the projection 81e of
the wafer back side press plate 81a presses the peripheral edge
portion of the lower (back) surface of the wafer W, and the
peripheral edge portion of the upper surface of the wafer W is
pressed against the abutment portion 80a of the cathode ring 80.
That is, the wafer W is held between the wafer back side press
plate 81a and the abutment portion 80a.
[0394] At this time, the projection 81e of the soft material is
resiliently deformed, and the abutment portion 80a is brought into
intimate contact with the entire peripheral edge portion of the
wafer W. That is, the peripheral edge portion of the upper surface
of the wafer W is sealed by the sealing surface 80s of the abutment
portion 80a. Thus, the areas of the wafer W and the cathode ring 80
to be brought into contact with the plating liquid are limited. At
the same time, the cathode 83 is biased into contact with the
peripheral edge portion of the upper surface (to-be-treated
surface) of the wafer W.
[0395] The system controller 155 controls the inversion driving
section 43 to invert the wafer holding/rotating mechanism 74a so
that the wafer W faces downward. Then, the pump P1 is actuated
under the control of the system controller 155 to supply the
plating liquid into the plating vessel 61a at a flow rate of about
10 l/min (see FIG. 7). Thus, the plating vessel 61a is filled with
the plating liquid, which is slightly raised from the edge of the
plating vessel 61a to overflow into the recovery vessel 62a.
[0396] In turn, the system controller 155 controls the lift
mechanism 44 to lower the wafer holding/rotating mechanism 74a.
When the distance between the lower surface of the wafer W and the
surface of the plating liquid is reduced to several millimeters,
the system controller 155 controls the plating power source 82 to
apply a first voltage between the anode 76 and the cathode 83, and
the lowering rate of the wafer holding/rotating mechanism 74a is
reduced (e.g., to about 50 mm/sec to about 0.1 mm/sec).
[0397] Thus, the lower surface of the wafer W is slowly brought
into contact with the surface of the plating liquid filled in the
plating vessel 61a. Thus, a portion of the lower surface of the
wafer W inward of the sealing surface 80s of the abutment portion
80a is entirely kept in contact with the plating liquid. That is,
air present between the wafer W and the plating liquid is allowed
to easily escape by slowly bringing the lower surface of the wafer
W into contact with the plating liquid.
[0398] Thus, the contact of the wafer W with the plating liquid is
completed. Then, the system controller 155 controls the lift
mechanism 44 to stop lowering the wafer holding/rotating mechanism
74a. In the aforesaid process, a period from the start of the
contact of the wafer W with the plating liquid to the completion of
the contact should be such that the seed layer formed on the lower
surface of the wafer W is hardly dissolved in the plating liquid.
With the wafer W in contact with the plating liquid, the distance
between the upper edge of the plating vessel 61a and the
to-be-treated surface of the wafer W is, for example, about 0.3 mm
to about 1 mm, and the cathode ring 80 is loosely fitted around the
upper edge of the plating vessel 61a.
[0399] Since the upper edge of the plating vessel 61a is located
adjacent the to-be-treated surface of the wafer W as described
above, the plating liquid can be kept in contact with the
to-be-treated surface of the wafer W ranging from the center to the
peripheral portion abutting against the abutment portion 80a. Thus,
the uniformity in the thickness of the film formed by the plating
is improved. The plating liquid flows in the form of a laminar flow
from the center to the periphery of the wafer W in the vicinity of
the interface of the wafer W, and then flows into the plating
liquid recovery vessel 62a through a gap between the upper edge of
the plating vessel 61a and the wafer W.
[0400] Even if air bubbles are trapped between the wafer W and the
plating liquid, the air bubbles flow out of the plating vessel 61a
together with the plating liquid. Since the angle formed between
the lower surface of the wafer W and the inclined surface 80g is
obtuse (see FIG. 12), the air bubbles can easily be expelled out of
the plating vessel 61a. The laminar flow of the plating liquid
occurring in the vicinity of the lower surface of the wafer W and
the absence of the air bubbles under the lower surface of the wafer
W make it possible to form a uniform film by the plating.
[0401] Subsequently, the system controller 155 controls the
rotative driving mechanism 45 to rotate the wafer W at a relatively
low rotation speed (e.g., 10 rpm to 100 rpm), and then controls the
plating power source 82 to apply a second voltage (plating voltage)
between the anode 76 and the cathode 83 for several minutes. The
second voltage is set for electrical energization of the anode 76
and the cathode 83 according to a predetermined electric current
pattern. Further, the valve 201V is opened under the control of the
system controller 155 to introduce the cathode cleaning liquid into
the fluid channels 81c, 81d.
[0402] Electrons are donated to copper ions in the plating liquid
in the interface between the plating liquid and the lower surface
of the wafer W connected to the cathode 83 by the application of
the second voltage between the anode 76 and the cathode 83, so that
copper atoms are deposited on the lower surface of the wafer W.
That is, the lower surface of the wafer W is plated with copper.
The plating liquid and the wafer W are moved relative to each other
by the rotation of the wafer W, whereby the uniformity of the
plating of the wafer W is improved.
[0403] Since the wafer W has an outer diameter virtually equal to
the inner diameter of the plating vessel 61a and the anode 76
virtually covers the entire plating vessel 61a as seen in plan, a
generally uniform electric field is formed between the anode 76 and
the seed layer formed on the lower surface of the wafer W. Thus,
the copper film formed by the plating has a uniform thickness.
[0404] Iron ions as an oxidizing/reducing agent are present in the
form of divalent and trivalent iron ions in the plating liquid. The
copper supply source (copper tube) housed in the major constituent
managing section 2 (see FIG. 1) is deprived of electrons by the
trivalent iron ions to release copper ions, while the trivalent
iron ions are turned into divalent iron ions. On the other hand,
the divalent iron ions donate electrons to the anode 76 thereby to
be turned into trivalent iron ions.
[0405] In this embodiment, the mesh anode 76 has a sufficiently
great surface area (e.g., a surface area two to ten times the area
to be plated). Further, the plating liquid can be applied to the
entire anode 76 at a sufficiently high flow rate by the shower head
75. Thus, a sufficient amount of divalent iron ions can be supplied
to the a node 76 to promote the reaction in which the divalent iron
ions donate electrons to the anode 76 thereby to be turned into
trivalent iron ions.
[0406] Thus, the iron ions cyclically experience the oxidization
and the reduction, so that the amount of electrons transferred
between the plating liquid and the anode 76 is virtually balanced
with the amount of electrons transferred between the cathode 83
(the lower surface of the wafer W) and the plating liquid.
[0407] Therefore, the plating process is free from bubbles of
active oxygen, which may otherwise be generated when the
oxidizing/reducing agent is not used. Thus, oxidative decomposition
of the additives contained in the plating liquid can be retarded.
Further, it is possible to eliminate the possibility that the
oxygen bubbles adhere on the lower surface of the wafer W and fill
the fine holes or grooves formed in the surface (lower surface) of
the wafer W to hinder the plating.
[0408] The plating liquid is drawn by the rotating wafer W in the
vicinity of the interface between the plating liquid and the wafer
W, and subjected to a centrifugal force. However, the plating
liquid can assuredly be introduced into the recovery vessel 62a by
the projection 80p of the cathode ring 80.
[0409] The cathode cleaning liquid introduced into the fluid
channels 81c, 81d flows out of the peripheral openings of the wafer
back side press plate 81a, and is introduced into the cathode
cleaning liquid collection vessel 210 through the fluid channels
80f (see FIG. 12). Thus, the cathode 83 is cleaned with the cathode
cleaning liquid. At this time, the cathode cleaning liquid flows
over the peripheral edge portion of the wafer W, but the particles
generated by the sliding components of the rotary joint 191 are not
introduced into the fluid channels 81c, 81d. Hence, there is no
possibility that the particles adhere on the wafer W.
[0410] The plating liquid is present opposite from the cathode 83
with respect to the wafer W and the abutment portion 80a. That is,
the cathode 83 contacts the portion of the wafer W which is limited
in contact with the plating liquid by the abutment portion 80a.
Therefore, the plating liquid does not flow to the cathode 83 if
the peripheral edge portion of the wafer W is sufficiently sealed
by the sealing surface 80s of the abutment portion 80a. On the
other hand, if the sealing between the wafer W and the abutment
portion 80a is insufficient, the plating liquid flows into a gap
between the wafer W and the abutment portion 80a to reach the
cathode 83.
[0411] If the plating process is continued with the plating liquid
left leaking through the gap between the wafer W and the abutment
portion 80a, an unintended portion of the lower surface of the
wafer W is plated. This influences the thickness of the film formed
on the predetermined portion of the lower surface of the wafer W by
the plating so that the film formed by the plating has a smaller
thickness in the vicinity of the abutment portion 80a than in the
other region. Therefore, the wafer W is non-uniformly plated. If
the electrically energized cathode 83 is kept in contact with the
plating liquid, the cathode 83 is plated, making it impossible to
properly electrically energize the wafer W.
[0412] However, the plating liquid reaching the cathode 83 is
washed away by the cathode cleaning liquid, so that the cathode 83
is kept clean. Then, the cathode cleaning liquid containing the
plating liquid flows into the liquid trap 211 from the cathode
cleaning liquid collection vessel 210.
[0413] The cathode cleaning liquid and the mixture of the cathode
cleaning liquid and the plating liquid differ in electrical
conductivity. Where the cathode cleaning liquid is deionized water,
for example, the electrical conductivity of the cathode cleaning
liquid is drastically increased by the plating liquid slightly
mixed in the cathode cleaning liquid. Therefore, a threshold is
properly set for the electrical conductivity measured by the
conductivity meter 212, so that the system controller 155 can
detect the leakage of the plating liquid from the gap between the
wafer W and the abutment portion 80a on the basis of the output
signal of the conductivity meter 212.
[0414] Upon detection of the leakage of the plating liquid, the
operation of the plating unit 20a is automatically interrupted
under the control of the system controller 155, and the operator is
informed of the leakage of the plating liquid. This prevents
continuation of uneven plating of the wafer W to avoid continuous
production of defective products, and prevents the cathode 83 from
being continuously plated.
[0415] The cathode cleaning liquid (liquid) may be supplied to a
region other than the cathode 83 where the intrusion of the plating
liquid is prevented (restricted). Even in this case, the leakage of
the plating liquid can be detected on the basis of the output
signal of the conductivity meter 212 if the plating liquid is
leaked from the gap between the wafer W and the abutment portion
80a and enters the fluid channel.
[0416] After the plating process is performed on the wafer W for a
predetermined period, the system controller 155 controls the
plating power source 82 to stop the energization between the anode
76 and the cathode 83, and controls the lift mechanism 44 to lift
the wafer W so that the lower surface of the wafer W is spaced
several millimeters apart from the surface of the plating liquid
filled in the plating vessel 61a.
[0417] Further, the system controller 155 controls the rotative
driving mechanism 45 to rotate the wafer W at a relatively high
speed (e.g., 200 rpm to 1000 rpm) for several tens seconds. Thus,
the plating liquid is laterally spun off from the lower surface of
the wafer W. At this time, the plating liquid spun off from the
lower surface of the wafer W is also introduced into the recovery
vessel 62a to 62d. In this process, the plated surface of the wafer
W is kept covered with a film of the plating liquid rather than
completely dried. Thus, the plated surface of the wafer W is
prevented from being corroded during transportation of the wafer
W.
[0418] Upon completion of the energization by the plating power
source 82, the valve 201V is closed and the valve 202V is opened
under the control of the system controller 155. Thus, the cathode
cleaning liquid remaining in the fluid channels 81c, 81d is purged
by nitrogen gas, and the cathode cleaning liquid in the fluid
channels 80f is laterally drained by a centrifugal force. The
cathode cleaning liquid remaining in the leak pipe 204 may be
sucked to be drained by the ejector not shown.
[0419] In turn, the system controller 155 controls the rotative
driving mechanism 45 to stop the rotation of the wafer W, and
controls the lift mechanism 44 to lift the wafer holding/rotating
mechanism 74a to a predetermined position. Then, the system
controller 155 controls the inversion driving section 43 to invert
the wafer holding/rotating mechanism 74a so that the wafer W faces
upward. The rotation angular position of the spin base 78 is
adjusted so that the circumferential portion of the spin base 78
having a wider support post interval is positioned in opposed
relation to the second transport path 15. The spin base 78 is kept
at the rotation angular position by a retention torque of the
second motor 45a.
[0420] Thereafter, the system controller 155 controls the susceptor
movement mechanism 46 to move the wafer back side press plate 81a
down toward the rotary pipe 77, whereby the wafer W is disengaged
from the wafer back side press plate 81a. At this time, the wafer W
is smoothly released from the sealing surface 80s by the resilience
of the cathode 83, so that the wafer W is supported on the wafer
transfer pins 84 as shown in FIG. 20. Since the cathode cleaning
liquid is not present in the fluid channels 80f, the cathode
cleaning liquid does not drip on the upper surface (plated surface)
of the wafer W.
[0421] After the wafer W is moved apart from the abutment portion
80a, the plating liquid remaining on the plated surface of the
wafer W is sucked through a gap between the sealing surface 80s and
the wafer W, so that the contact portions 83c of the cathode 83 are
contaminated with the plating liquid. However, the plating liquid
adhering to the contact portions 83c is rinsed off with the cathode
cleaning liquid before and during the plating process to be
performed on the next wafer W. Thus, the next plating process can
be performed with the contact portions 83c kept clean.
[0422] The treated wafer W is unloaded through the space between
the support posts 79 by the retractable arm 42 or the retractable
arm 41 of the transport robot TR. Thus, the plating process on the
single wafer W is completed.
[0423] The plating process may be performed simultaneously in the
plating cups 56a to 56d by simultaneously actuating the four pumps
P1 to P4, or in some of the plating cups 56a to 56d by actuating
corresponding ones of the pumps P1 to P4.
[0424] FIG. 21 is a schematic side view of the plating unit 20a.
With reference to FIG. 21, an explanation will be given to an
operation to be performed for the maintenance of the plating unit
20a. Since the plating units 20b to 20d have the same construction
as the plating unit 20a, the maintenance operation can be performed
in the same manner.
[0425] An outer cover 220 is provided as a part of the barrier wall
of the enclosure 30 on a side of the plating unit 20a opposite from
the second transport path 15 (see FIG. 2). The outer cover 220 is
removable from the enclosure 30. When the maintenance operation of
the plating unit 20a is performed, the outer cover 220 is
removed.
[0426] One end of the guide 44a of the lift mechanism 44 (a lower
end of the guide 44a when located vertically) is hinged to a first
frame 222a of the wafer treating section 1. Thus, the guide 44a is
pivotal about a pivot axis 223 which extends generally horizontally
and parallel to the length of the second transport path 15. The
pivot shaft 223 is located closer to the outer cover 220 than the
plating cup 56a at a lower position than the plating cup 56a.
[0427] The guide 44a can be fixed to a frame 222b of the wafer
treating section 1 by a fixture screw 224. The position at which
the guide 44a is fixed by the fixture screw 224 is higher than the
position of the pivot axis 223. With the guide 44a fixed to the
frame 222b by the fixture screw 224, the vertical base 182 is
located vertically, and the wafer holding/rotating mechanism 74a is
located above the plating cup 56a. In this state, the plating
process is performed.
[0428] The pivoting of the guide 44a is restricted by the frame
222b so as not to be inclined toward the plating cup 56a. That is,
the guide 44a is only permitted to pivot apart from the plating cup
56a from a vertical position.
[0429] A gas damper 225 is pivotally coupled at one end thereof to
a part of the guide 44a adjacent to the pivot shaft 223. The gas
damper 225 is pivotally coupled at the other end thereof to a frame
222c of the wafer treating section 1. The coupling between the
frame 222c and the gas damper 225 is located at a lower position
than the coupling between the frame 222a and the gas damper 225 and
the pivot shaft 223. The gas damper 225 includes a cylinder and a
piston, and is designed so that the piston resists a force exerted
thereon inwardly of the cylinder by the pressure of gas charged in
the cylinder. A piston end of the gas damper 225 is attached to the
guide 44a, while a cylinder end of the gas damper 225 is attached
to the frame 222c.
[0430] In the lift mechanism 44, a support member 44b projects from
the guide 44a toward the outer cover 220 when the guide 44a is
located vertically. When the wafer holding/rotating mechanism 74a
and the lift mechanism 44 are pivoted about 90 degrees around the
pivot shaft 223 from the vertical position of the guide 44a, an end
of the support member 44b abuts against a stopper 227 provided on
the frame of the wafer treating section 1 for prevention of further
pivoting of the guide 44a. In this state, the guide 44a is kept
generally horizontally. A portion of the stopper 227 to be brought
into abutment against the support member 44b is covered with a
rubber, so that a shock exerted thereon can be alleviated when the
support member 44b abuts against the stopper 227.
[0431] When the maintenance operation of the plating unit 20a is
performed, the outer cover 220 is removed with the plating process
stopped. Thus, the operator can perform the maintenance operation
on the side of the apparatus where the outer cover has been
attached. Subsequently, the fixture screw 224 is removed, and the
wafer holding/rotating mechanism 74a is gradually inclined toward
the operator by pivoting the guide 44a about the pivot shaft
223.
[0432] At this time, the gas damper 225 is operative so that the
piston is forced into the cylinder. Therefore, only a small force
is required for the operator to incline the wafer holding/rotating
mechanism 74a with the aid of the resilient force of the gas damper
225. Even if the operator inadvertently lets his hands off from the
wafer holding/rotating mechanism 74a, the resilient force of the
gas damper 225 prevents the wafer holding/rotating mechanism 74a
from abruptly falling down.
[0433] With the guide 44a kept generally horizontally, the support
member 44b abuts against the stopper 227, so that the wafer
holding/rotating mechanism 74a cannot be moved further more. In
this state, the wafer holding/rotating mechanism 74a projects
laterally from the wafer treating section 1, so that the top of the
plating cup 56a is open. This state is illustrated by a
two-dot-and-dash line in FIG. 21. Thus, the operator can easily
access an intended portion, and easily perform the maintenance
operation.
[0434] Next, an explanation will be given to the maintenance of the
plating cup 56a to 56d. The plating process should be performed
with the rotation axis (center axis) of the cathode ring 80
coinciding with the center axis of the plating vessel 61a to 61d.
This is because the cathode ring 80 is spaced a very small distance
from the upper edge of the plating vessel 61a to 61d in the plating
process and, hence, the plating vessel 61a to 61d interferes with
the cathode ring 80 if the rotation axis (center axis) of the
cathode ring 80 is offset from the center axis of the plating
vessel 61a to 61d (see FIG. 12). The position and attitude of the
plating cup 56a to 56d is properly adjusted so that the rotation
axis (center axis) of the cathode ring 80 coincides with the center
axis of the plating vessel 61a to 61d.
[0435] Unless the upper edge of the plating vessel 61a to 61d is
present within a generally horizontal plane, the plating liquid
cannot be raised from the entire edge of the plating vessel 61a to
61d so as to be brought into contact with the wafer W. In this
case, the wafer W held generally horizontally and the upper edge of
the plating vessel 61a to 61d cannot be spaced a generally constant
distance from each other in adjacent relation by the wafer
holding/rotating mechanism 74a to 74d.
[0436] Therefore, the upper edge of the plating vessel 61a to 61d,
if not kept horizontal, should be leveled horizontally.
[0437] FIG. 22 is a schematic side view of the plating cup 56a.
With reference to FIG. 22, an explanation will be given to how to
adjust the position and attitude of the plating cup 56a and how to
level the upper edge of the plating cup 56a within a generally
horizontal plane. Since the plating cups 56b to 56d have the same
construction as the plating cup 56a, the adjustment can be achieved
in the same manner.
[0438] A first planar base plate 230 is unitarily fixed to the
lower portion (bottom) of the plating cup 56a. The first base plate
230 is slightly greater in size than the bottom face of the plating
cup 56a as viewed in plan, and laterally projects from the bottom
of the plating cup 56a. A second planar base plate 231 having a
slightly greater size than the first base plate 230 as viewed in
plan is attached to the lower side of the first base plate 230
(opposite from the plating cup 56a). The second base plate 231 is
fixed to a frame 236 of the wafer treating section 1.
[0439] The first base plate 230 and the second base plate 231 each
have through-holes extending through the thickness thereof, and the
branch liquid supply pipe 58a and the branch return pipes 63a
extend through these through-holes. The branch liquid supply pipe
58a and the branch return pipes 63a are connected to the plating
cup 56a via joints 239 of a resin (e.g., a fluororesin). The joints
239 facilitate the attachment and detachment of the branch liquid
supply pipe 58a and the branch return pipes 63a with respect to the
plating cup 56a.
[0440] The first base plate 230 has at least three fixture holes
233 formed in a peripheral edge portion thereof as extending
through the thickness thereof. The second base plate 231 has inner
thread portions provided therein in association with the fixture
holes 233. Fixture screws 235 having outer thread portions are
respectively inserted through the fixture holes 233 and tightened
into the inner thread portions 234 formed in the second base plate
231. Thus, the first base plate 230 is fixed to the second base
plate 231.
[0441] The inner diameter of the fixture holes 233 is greater than
the outer diameter of the fixture screws 235. For example, the
fixture holes 233 each have an inner diameter of about 10 mm, while
the fixture screws 235 each have an outer diameter of about 6 mm.
In this case, the first base plate 230 is movable by about 4 mm in
any directions within the plane of the first base plate 230. In
this case, washers 237 each having an outer diameter of 18 mm, for
example, are provided between screw heads of the fixture screws 235
and the first base plate 230 to prevent the screw heads of the
fixture screws 235 from falling into the fixture holes 233.
[0442] With the fixture screws loosened, the first base plate 230
can be moved in any directions within the plane of the first base
plate 230 to adjust the horizontal position of the plating vessel
61a.
[0443] The second base plate 231 is fixed to the frame 236 by at
least three pairs of push screws 238A and pull screws 238B arranged
in circumferentially spaced relation. The heights of the second
base plate 231 from the frame 236 at the positions of the
respective pairs of the push screws 238A and the pull screws 238B
can be adjusted by properly adjusting the push screws 238A and the
pull screws 238B. Thus, the inclination of the second base plate
231 can be adjusted. Therefore, the attitude of the plating cup 56a
can be adjusted.
[0444] In general, the upper edge of the plating vessel 61a is
leveled within a generally horizontal plane by attaching the first
base plate 230 to the horizontally leveled second base plate 231 in
intimate contact with the second base plate 231. For the leveling
of the upper edge of the plating vessel 61a, a leveler is first
placed on the second base plate 231 with the plating vessel 61a
removed, and then the second base plate 231 is leveled
horizontally. Thereafter, the first base plate 230 is attached to
the second base plate 231 in intimate contact with the second base
plate 231. Thus, the upper edge of the plating vessel 61a is
leveled within a generally horizontal plane.
[0445] At this time, the fixture screws 235 are loosened. In turn,
the wafer holding/rotating mechanism 74a is lowered, and the first
base plate 230 is moved with respect to the second base plate 231
so that the cathode ring 80 is fitted around the upper edge of the
plating vessel 61a. Thus, the horizontal position of the plating
vessel 61a is adjusted.
[0446] In general, the rotation axis (center axis) of the cathode
ring 80 and the center axis of the plating vessel 61a are adjusted
generally parallel to each other with the wafer holding/rotating
mechanism 74a and the plating cup 56a kept in opposed relation.
Therefore, the plating vessel 61a is properly positioned in the
aforesaid manner so that the center axis of the plating vessel 61a
and the rotation axis (center axis) of the cathode ring 80 can
virtually coincide with each other. With the plating vessel 61a
thus properly positioned, the fixture screws 235 are tightened to
fix the position of the plating vessel 61a.
[0447] In use of the plating cup 56a (plating vessel 61a) adjusted
in the aforesaid manner, the upper edge of the plating vessel 61a
and the wafer W held between the cathode ring 80 and the wafer
holding/rotating mechanism 74a can be spaced a very small distance
from each other in adjacent relation without interference. Since
the plating liquid can be raised from the entire edge of the
plating vessel 61a, the lower surface of the wafer W held by the
wafer holding/rotating mechanism 74a can easily and generally
entirely be brought into contact with the plating liquid.
[0448] FIG. 23 is a schematic sectional view illustrating the
common construction of the bevel etching units 21a, 21b.
[0449] A spin chuck 86 for generally horizontally holding and
rotating the wafer W is provided in a generally cylindrical cup 85.
The spin chuck 86 is adapted to hold the wafer W by sucking a
center portion of the lower surface of the wafer W without
contacting the peripheral edge of the wafer W. The spin chuck 86
has a vertical rotation shaft 87, and a rotative driving force is
transmitted from a rotative driving mechanism 88 to the rotation
shaft 87. A lift mechanism 89 for moving up and down the spin chuck
86 is coupled to the spin chuck 86, so that the spin chuck 86 can
be brought into a state where its upper portion is accommodated in
the cup 85 and into a state where its upper portion is located
above an upper edge of the cup 85.
[0450] The cup 85 includes three cups 85a to 85c coaxially
arranged. The outermost one of the cups 85a to 85c has an upper
edge located at the highest position, and the middle cup 85b has an
upper edge located at the lowest position. An annular treatment
liquid guide plate 85d as seen in plan is coupled to an upper edge
of the innermost cup 85c. An outer edge of the treatment liquid
guide plate 85d is bent to be inserted into a space between the cup
85a and the cup 85b.
[0451] A treatment liquid collection vessel 97 having an open top
is defined between the cup 85a and the cup 85b, and an air outlet
vessel 98 is defined between the cup 85b and the cup 85c. A liquid
drain port 97a is provided in the bottom of the treatment liquid
collection vessel 97, and an air outlet port 98a is provided in the
bottom of the air outlet vessel 98.
[0452] A rinse nozzle 90 is provided above the cup 85. A rinse
liquid pipe 91 is connected in communication with the rinse nozzle
90, and a rinse liquid supply source 92 is connected to the rinse
liquid pipe 91. A valve 91V is provided in the rinse liquid pipe
91. With the valve 91V being open, the rinse liquid can be
discharged through the rinse nozzle 90 to be supplied to the upper
surface of the wafer W held by the spin chuck 86.
[0453] Another rinse nozzle 99 extends through the treatment liquid
guide plate 85d from the lower side. A rinse liquid pipe 100 is
connected in communication with the rinse nozzle 99, and the rinse
liquid supply source 92 is connected to the rinse liquid pipe 100.
A valve 100V is provided in the rinse liquid pipe 100. With the
valve 100V being open, the rinse liquid can be discharged through
the rinse nozzle 99 to be supplied to the lower surface of the
wafer W held by the spin chuck 86.
[0454] The rinse liquid may be, for example, deionized water. In
this case, the rinse liquid (deionized water) can be supplied into
the rinse liquid pipes 91, 100 through the deionized water pipe 32
(see FIG. 3) extending through the deionized water pipe
introduction port 32h formed in the enclosure 30.
[0455] An etching pipe 93 is provided generally vertically above
the cup 85. The etching pipe 93 has a groove 94 provided in a lower
end portion thereof as opening horizontally toward the center of
the cup 85 in association with the surface of the wafer W held by
the spin chuck 86. The peripheral edge of the wafer W can be
inserted in the groove 94. The inner space of the groove 94 and the
inner space of the etching pipe 93 communicate with each other.
[0456] A movement mechanism 95 is coupled to the etching pipe 93.
The etching pipe 93 can be moved vertically and radially of the cup
85 by the movement mechanism 95. Thus, the etching pipe 93 can be
moved between a treatment position at which the peripheral edge of
the wafer W is inserted in the groove 94 and a retracted position
at which the etching pipe 93 is retracted from the treatment
position apart from the wafer W. The etching pipe 93 can also be
retracted laterally beyond the cup 85.
[0457] The etching pipe 93 is connected via the post-treatment
agent pipe P14 to an etching liquid supply source 96 disposed in
the post-treatment agent supplying section 4 (see FIG. 1) and
containing the etching liquid. A valve 93V is provided in the
post-treatment agent pipe P14 between the etching pipe 93 and the
etching liquid supply source 96. With the valve 93V being open, the
etching liquid can be supplied to the inner space of the groove 94.
The flow rate of the etching liquid can also be adjusted by the
valve 93V. The etching liquid may be, for example, a mixture of
sulfuric acid, hydrogen peroxide aqueous solution and water.
[0458] The operations of the rotative driving mechanism 88, the
lift mechanism 89 and the movement mechanism 95, and the opening
and closing of the valves 91V, 100V, 93V are controlled by the
system controller 155.
[0459] When the peripheral edge of the wafer W is to be etched by
the bevel etching unit 21a, 21b, the system controller 155 first
controls the movement mechanism 95 to retract the etching pipe 93
at the retracted position.
[0460] In turn, the system controller 155 controls the lift
mechanism 89 to move up the spin chuck 86 so that the upper portion
of the spin chuck 86 is located above the upper edge of the cup 85.
The wafer W subjected to the plating process in the plating section
12 is loaded into the bevel etching unit 21a or 21b by the
retractable arm 41 or the retractable arm 42 of the transport robot
TR (see FIGS. 5(a) to 5(c)), and held by the spin chuck 86 by
suction with the center of the wafer W coinciding with the center
axis of the rotation shaft 87. The surface of the wafer W subjected
to the plating process faces upward.
[0461] Thereafter, the system controller 155 controls the lift
mechanism 89 to move down the spin chuck 86. Thus, the wafer W held
by the spin chuck 86 is surrounded by the cup 85a. Then, the system
controller 155 controls the rotative driving mechanism 88 to rotate
the wafer W held by the spin chuck 86. The rotation speed of the
wafer W is, for example, about 500 rpm.
[0462] In this state, the valves 91V and 100V are opened under the
control of the system controller 155. Thus, the rinse liquid is
supplied to the upper and lower surfaces of the wafer W from the
rinse nozzles 90 and 99. The rinse liquid spreads toward the
peripheral edge of the wafer W by a centrifugal force, and flows
over the entire upper surface of the wafer W and the lower surface
of the wafer W except a portion thereof in contact with the spin
chuck 86. Thus, the wafer W is cleaned.
[0463] The rinse liquid is spun off laterally of the wafer W by the
centrifugal force, and flows over the interior of the cup 85a and
the upper surface of the treatment liquid guide plate 85d down into
the treatment liquid collection vessel 97. The rinse liquid is
introduced into a collection tank not shown through the liquid
drain port 97a. Further, gas is exhausted from the cup 85 through
the air outlet port 98a by an air exhauster system not shown. Thus,
mist of the rinse liquid and the like are prevented from scattering
out of the cup 85.
[0464] After the rinsing process is performed for a predetermined
period, the valves 91V, 100V are closed under the control of the
system controller 155. The wafer W is continuously rotated, whereby
the rinse liquid remaining on the wafer W is mostly spun off.
[0465] Subsequently, the system controller 155 controls the
movement mechanism 95 to move the etching pipe 93 to the treatment
position. Thus, the peripheral edge of the wafer W is inserted in
the groove 94 as shown in FIG. 23. At this time, the rotation speed
of the wafer W may be, for example, about 500 rpm. Then, the valve
93V is opened under the control of the system controller 155. The
flow rate of the etching liquid may be, for example, 20 ml/min.
Thus, the etching liquid is supplied into the groove 94 from the
etching liquid supply source 96. The etching liquid flows out of
the groove 94, so that the groove 94 is virtually filled with the
etching liquid.
[0466] Since the peripheral edge of the wafer W is inserted in the
groove 94, a part of the thin copper film formed on the peripheral
edge of the wafer W is dissolved by the etching liquid. With the
wafer W being rotated, the peripheral edge of the wafer W is moved
relative to the etching pipe 93 located at the treatment position.
As a result, the entire peripheral edge of the wafer W is etched.
An etching width is determined by an insertion depth of the wafer W
in the groove 94, so that the etching process can accurately be
performed with a desired etching width.
[0467] Like the rinse liquid, the etching liquid spun off laterally
of the wafer W by a centrifugal force is once collected in the
collection vessel 97, and then introduced into the collection tank
not shown through the liquid drain port 97a. During this period,
gas is continuously exhausted through the air outlet port 98a, so
that mist of the etching liquid is prevented from scattering out of
the cup 85.
[0468] After the etching liquid is continuously supplied for a
predetermined period (e.g., several tens seconds) for the etching
of the thin copper film on the peripheral edge of the wafer W, the
valve 93V is closed under the control of the system controller 155
to stop the supply of the etching liquid to the groove 94. Thus,
the etching process for etching the peripheral edge of the wafer W
is completed in the absence of the etching liquid in the groove
94.
[0469] Thereafter, the valves 91V, 100V are opened again under the
control of the system controller 155 to supply the rinse liquid to
the surfaces of the wafer W. Thus, the etching liquid remaining on
the peripheral edge portion of the wafer W is rinsed away with the
rinse liquid. During this period, the system controller 155
controls the movement mechanism 95 to move the etching pipe 93 to
the retracted position.
[0470] After the rinse liquid is continuously supplied for a
predetermined period (e.g., about one minute), the valves 91V, 100V
are closed under the control of the system controller 155 to stop
the supply of the rinse liquid. The system controller 155 controls
the rotative driving mechanism 88 to rotate the spin chuck 86 at a
high rotation speed (e.g., about 1000 rpm) for a predetermined
period (e.g., several tens seconds) for spinning off the rinse
liquid from the wafer W for drying. Then, the rotation of the spin
chuck 86 is stopped.
[0471] Subsequently, the system controller 155 controls the lift
mechanism 89 to move up the spin chuck 86 so that the wafer W held
by the spin chuck 86 is located above the upper edge of the cup 85.
Then, the wafer W is released out of the suction-held state.
[0472] In turn, the treated wafer W is unloaded by the retractable
arm 42 or the retractable arm 41 of the transport robot TR. Thus,
the etching process for the etching of the peripheral edge of the
single wafer W is completed. Since no thin copper film is present
on the peripheral edge of the treated wafer W, there is no
possibility that copper adheres on the substrate holder hand 41c,
42c (see FIG. 5(a)) when the peripheral edge of the wafer is held
by the substrate holder hand 41c, 42c in the subsequent steps.
[0473] In this embodiment, the cup 85 is fixed, and the spin chuck
86 is adapted to be moved up and down by the lift mechanism 89.
However, it is merely necessary to vertically move the spin chuck
86 and the cup 85 relative to each other. For example, the spin
chuck 86 may vertically be fixed, and the cup 85 may be adapted to
be moved up and down. Even in this case, the upper portion of the
spin chuck 86 can be located above the upper edge of the cup 85, so
that the wafer W can be loaded and unloaded by the retractable arm
41 or the retractable arm 42.
[0474] FIG. 24 is a schematic sectional view illustrating the
common construction of the cleaning units 22a, 22b.
[0475] A spin chuck 102 for generally horizontally holding and
rotating the wafer W is provided in a generally cylindrical cup
101. The spin chuck 102 includes a vertical rotation shaft 102a and
a disk spin base 102b provided at an upper end of the rotation
shaft 102a perpendicularly to the rotation shaft 102a. A plurality
of chuck pins 102e are provided upright on a peripheral edge
portion of an upper surface of the spin base 102b in
circumferentially spaced relation. The chuck pins 102e
cooperatively support a peripheral edge portion of the lower
surface of the wafer W in abutment against the peripheral surface
(circumferential surface) of the wafer W for holding the wafer
W.
[0476] A rotative driving force is transmitted to the rotation
shaft 102a of the spin chuck 102 from a rotative driving mechanism
103. A lift mechanism 104 for moving up and down the spin chuck 102
is coupled to the spin chuck 102, so that the spin chuck 102 can be
brought into a state where its upper portion is accommodated in the
cup 101 and into a state where its upper portion is located above
an upper edge of the cup 101.
[0477] The cup 101 includes three cups 101a to 101c coaxially
arranged. The outermost one of the cups 101a to 101c has an upper
edge located at the highest position, and the middle cup 101b has
an upper edge located at the lowest position. An annular treatment
liquid guide plate 101d as seen in plan is coupled to an upper edge
of the innermost cup 101c. An outer edge of the treatment liquid
guide plate 101d is bent to be inserted into a space between the
cup 101a and the cup 101b.
[0478] A treatment liquid collection vessel 105 having an open top
is defined between the cup 101a and the cup 101b, and an air outlet
vessel 106 is defined between the cup 101b and the cup 101c. A
liquid drain port 105a is provided in the bottom of the treatment
liquid collection vessel 105, and an air outlet port 106a is
provided in the bottom of the air outlet vessel 106.
[0479] A nozzle 107 is provided above the cup 101. The nozzle 107
is connected in communication with the rinse liquid supply source
via a valve 107V. By opening the valve 107V, the rinse liquid can
be discharged toward the wafer W held by the spin chuck 102 from
the nozzle 107.
[0480] The rotation shaft 102a has a treatment liquid supply
channel 102c extending therethrough axially thereof, and an open
upper end serving as a treatment liquid outlet port 102d. The
cleaning liquid can be supplied into the treatment liquid supply
channel 102c through the post-treatment agent pipe P14 from a
cleaning liquid supply source provided in the post-treatment agent
supplying section 4 (see FIG. 1). The rinse liquid can also be
supplied into the treatment liquid supply channel 102c from the
rinse liquid supply source.
[0481] The cleaning liquid may be, for example, a mixture of
sulfuric acid, a hydrogen peroxide aqueous solution and water. The
rinse liquid may be, for example, deionized water. In this case,
the rinse liquid (deionized water) can be supplied into the
treatment liquid supply channel 102c and the nozzle 107 via the
deionized water pipe 32 (see FIG. 3) extending through the
deionized water pipe introduction port 32h formed in the enclosure
30.
[0482] A valve 108V is provided between the treatment liquid supply
channel 102c and the cleaning liquid supply source. A valve 109V is
provided between the treatment liquid supply channel 102c and the
rinse liquid supply source. By closing the valve 109V and opening
the valve 108V, the cleaning liquid can be discharged from the
treatment liquid outlet port 102d. By closing the valve 108V and
opening the valve 109V, the rinse liquid can be discharged from the
treatment liquid outlet port 102d. Thus, the cleaning liquid or the
rinse liquid can be supplied to the center of the lower surface of
the wafer W held by the spin chuck 102.
[0483] The operations of the rotative driving mechanism 103 and the
lift mechanism 104, and the opening and closing of the valves 107V,
108V, 109V are controlled by the system controller 155.
[0484] When the wafer W is to be cleaned in the cleaning unit 22a
or 22b, the system controller 155 controls the lift mechanism 104
to move up the spin chuck 102 so that the upper portion of the spin
chuck 102 is located above the upper edge of the cup 101. The wafer
W subjected to the bevel etching process in the bevel etching unit
21a or 21b is loaded into the cleaning unit 22a or 22b by the
retractable arm 41 or the retractable arm 42 of the transport robot
TR (see FIGS. 5(a) to 5(c)), and mechanically held by the chuck
pins 102e with the center of the wafer W coinciding with the center
axis of the rotation shaft 102a.
[0485] Thereafter, the system controller 155 controls the lift
mechanism 104 to move down the spin chuck 102. Thus, the wafer W
held by the spin chuck 102 is surrounded by the cup 101a. Then, the
system controller 155 controls the rotative driving mechanism 103
to rotate the wafer W held by the spin chuck 102. The rotation
speed of the wafer W is, for example, about 500 rpm. Gas is
exhausted from the cup 101 through the air outlet port 106a by the
exhauster system not shown.
[0486] In this state, the valves 107V, 108V are opened under the
control of the system controller 155. Thus, the rinse liquid and
the cleaning liquid are discharged toward the wafer W from the
nozzle 107 and the treatment liquid outlet port 102d, respectively.
The rinse liquid and the cleaning liquid supplied to the surfaces
of the wafer W spread toward the peripheral edge of the wafer W by
a centrifugal force. Thus, the entire lower surface of the wafer W
is cleaned.
[0487] The rinse liquid and the cleaning liquid are spun off
laterally of the wafer W by the centrifugal force, and flows over
the interior of the cup 101a and the upper surface of the treatment
liquid guide plate 101d down into the treatment liquid collection
vessel 105. The rinse liquid and the cleaning liquid are introduced
into the collection tank not shown through the liquid drain port
105a. Further, gas is exhausted from the cup 101. Thus, mist of the
cleaning liquid can be exhausted through the air outlet port 106a
so as to be prevented from scattering out of the cup 101.
[0488] After this process is performed for a predetermined period,
the valve 108V is closed and the valve 109V is opened under the
control of the system controller 155. Thus, the rinse liquid is
discharged toward the lower surface of the wafer W from the
treatment liquid outlet port 102d. The supply of the rinse liquid
to the upper surface of the wafer W from the nozzle 107 is
continued. Thus, the cleaning liquid is rinsed away from the lower
surface of the wafer W. After this process is continued for a
predetermined period (e.g., about one minute), the valves 107V and
109V are closed under the control of the system controller 155 to
stop the supply of the rinse liquid to the wafer W.
[0489] Subsequently, the system controller 155 controls the
rotative driving mechanism 103 to rotate the wafer W held by the
spin chuck 102 at a high speed, for example, at about 2000 rpm.
Thus, the rinse liquid remaining on the wafer W is mostly spun off
for drying the wafer W. After the high-speed rotation of the wafer
W is continued for a predetermined period (e.g., several tens
seconds), the system controller 155 controls the rotative driving
mechanism 103 to stop the rotation of the wafer W.
[0490] In turn, the system controller 155 controls the lift
mechanism 104 to move up the spin chuck 102 so that the wafer W
held by the spin chuck 102 is located above the upper edge of the
cup 101. Thus, the wafer W is released from the chuck pins
102e.
[0491] Then, the treated wafer W is unloaded by the retractable arm
42 or the retractable arm 41 of the transport robot TR. Thus, the
cleaning process for the cleaning of the single wafer W is
completed.
[0492] In this embodiment, the cup 101 is fixed, and the spin chuck
102 is adapted to be moved up and down by the lift mechanism 104.
However, it is merely necessary to vertically move the spin chuck
102 and the cup 101 relative to each other. For example, the spin
chuck 102 may vertically be fixed, and the cup 101 may be adapted
to be moved up and down. Even in this case, the spin base 102b can
be located above the upper edge of the cup 101, so that the wafer W
can be loaded and unloaded by the retractable arm 41 or the
retractable arm 42.
[0493] FIG. 25 is a block diagram illustrating the construction of
a control system for the wafer treating section 1.
[0494] The system controller 155 is provided in the wafer treating
section 1, and controls the wafer treating section 1, the major
constituent managing section 2, the minor constituent managing
section 3 and the post-treatment agent supplying section 4 to
comprehensively manage the entire plating apparatus 10. More
specifically, the system controller 155 monitors the states of the
respective sections, sends proper control commands and data to the
respective sections, and takes in data from the respective
sections.
[0495] Hardware of the system controller 155 includes a central
processing unit (CPU) 155C having a processing capability of 10
MIPS (million instructions per second) or more, a storage device
155M including a semiconductor memory having a storage capacity of
10 Mbytes or more and a magnetic memory having a storage capacity
of 1 Mbyte or more, RS-232C compatible serial ports 280, RS-485
compatible serial ports 281, and a plurality of printed circuit
boards 155P. The magnetic memory may be, for example, a hard disk
(HD) incorporated in a hard disk drive (HDD), or a flexible disk
(FD) to be inserted in a flexible disk drive (FDD).
[0496] Software employed in the system controller 155 includes an
operating system, and application programs which are at least
partly described in a high-level language. These programs are
stored in the storage device 155M. The application programs include
recipes for performing the plating process, the bevel etching
process, the cleaning process and the like.
[0497] The system controller 155 is connected to a color display
156, a keyboard 157 and a pointing device (e.g., a mouse) 156p, so
that the operator can interact with the system controller 155 for
inputting and outputting information. The system controller 155 is
further connected to an audible alarm generator 158. When a certain
event occurs, e.g., when the leakage of the plating liquid occurs
which is judged on the basis of the output signal of the
conductivity meter 212 (see FIG. 9) or when the residual amount of
the copper supply source (copper tube) for supplying copper ions to
the plating liquid is reduced below a predetermined level, an
audible alarm is given, and information on the alarm is displayed
on the color display 156.
[0498] The system controller 155 is connected to the transport
controller 29 (see FIG. 2), the major constituent managing section
2 and the minor constituent managing section 3 via the RS-232C
compatible serial ports 280 by cables. The system controller 155 is
further connected to a motor controller 159 by a pulse-string
input/output cable, and connected to a pump controller 160, the
flow meters 60a to 60d and the absorptiometers 66A and 66B by
analog signal cables.
[0499] Thus, the system controller 155 is capable of controlling
motors provided in the rotative driving mechanisms 45, 88, 103 (see
FIGS. 9, 23 and 24), for example, via the motor controller 159, and
controlling the operations of the pumps P1 to P4 (see FIG. 7) in
the plating section 12, for example, via the pump controller
160.
[0500] Signals indicative of the flow rates from the flow meters
60a to 60d (see FIG. 7) are inputted as analog signals to the
system controller 155. Further, the system controller 155 controls
the operations of the absorptiometers 66A, 66B (e.g., light
emission of the light emitting sections 68A, 68B) on an analog
signal basis, and receives analog signals outputted from the light
receiving sections 69A, 69B.
[0501] The system controller 155 is further connected to the major
constituent managing section 2, the post-treatment agent supplying
section 4 and serial/parallel converters 161a, 161b via the RS-485
compatible serial ports 281 by cables. In FIG. 25, only two
serial/parallel converters 161a, 161b are shown, but the system
controller 155 may be connected to a greater number of
serial/parallel converters.
[0502] The serial/parallel converters 161a and 161b are
respectively connected to electromagnetic valves 162a and 162b, and
sensors 163a and 163b (e.g., the temperature sensor 70, the
electromagnetic conductivity meter 71, the ultrasonic level meter
72 (see FIG. 7)) via parallel cables. The electromagnetic valves
162a, 162b are capable of controlling air valves (e.g., the valves
91V, 101V (see FIG. 23) and the valve 107V (see FIG. 24)).
[0503] FIG. 26 is a schematic diagram illustrating the construction
of the major constituent managing section 2.
[0504] The major constituent managing section 2 includes at least
one copper dissolution tank (two copper dissolution tanks 110a,
110b in this embodiment) for supplying copper ions to the plating
liquid, a buffer container 111 for supplying a replacement liquid
to one of the copper dissolution tanks 110a, 110b not in use, and
an undiluted replacement liquid supplying section 112 for supplying
an undiluted replacement liquid as a source of the replacement
liquid to the buffer container 111.
[0505] Copper tubes 146 are provided as the copper supply source in
each of the copper dissolution tanks 110a, 110b. The plating liquid
is circulated through the plating liquid container 55 of the wafer
treating section 1 and the copper dissolution tank 110a, 110b,
whereby copper ions consumed by the plating are replenished in the
plating liquid. In the copper dissolution tank 110a (10b) through
which the plating liquid is not circulated in communication with
the plating liquid container 55, the surface of the copper tubes
146 can be maintained in a proper state by filling the replacement
liquid in the copper dissolution tank 110a (110b). This ensures
proper leach-out of copper ions from the copper tubes 146 when the
circulation of the plating liquid through the plating liquid
container 55 and the copper dissolution tank 110a (10b) is
started.
[0506] The copper dissolution tanks 110a, 110b each have a
cylindrical sealed structure having a closed bottom and a generally
vertical axis. The copper dissolution tank 110a, 110b is placed on
a weight meter 154a, 154b, which is adapted to measure the total
weight of the copper dissolution tank 110a, 110b including its
content.
[0507] The copper dissolution tank 110a, 110b includes an outer
pipe 116a, 116b constituting a side wall thereof, and an inner pipe
117a, 117b provided in the outer pipe 116a, 116b. An inner space of
the inner pipe 117a, 117b communicates with a space (hereinafter
referred to as "annular space 145") defined between the outer pipe
116a, 116b and the inner pipe 117a, 117b in a lower portion of the
copper dissolution tank 110a, 110b. The copper tubes 146 are
accommodated in the annular space 145.
[0508] The buffer container 111 has a cover 120 having a plurality
of piping ports for piping, and is virtually sealed. Upper and
lower portions of the buffer container 111 are connected in
communication with each other by a bypass pipe 125 vertically
extending along the exterior of the buffer container 111. A
constant volume check sensor 126 is provided at a predetermined
height on a lateral side of the bypass pipe 125 for detecting the
presence or absence of liquid at this predetermined height within
the bypass pipe 125.
[0509] The liquid (e.g., the replacement liquid) is allowed to
freely flow between the buffer container 111 and the bypass pipe
125, so that a liquid surface level in the buffer container 111 is
virtually equal to a liquid surface level in the bypass pipe 125.
Thus, the presence or absence of the liquid at the predetermined
height in the buffer container 111 can be detected by the constant
volume check sensor 126.
[0510] One end of a circulation pipe 118 is connected to the bottom
of the buffer container 111 via a piping port for communication
between the circulation pipe 118 and the buffer container 111. The
other end of the circulation pipe 118 is branched into branch
circulation pipes 121, 122 at a branch point B1. The branch
circulation pipe 121 is further branched into branch circulation
pipes 121a, 121b, while the branch circulation pipe 122 is further
branched into branch circulation pipes 122a, 122b.
[0511] The branch circulation pipes 121a and 121b are respectively
connected to upper portions of the inner pipes 117a and 117b of the
copper dissolution tanks 110a and 110b. The branch circulation
pipes 122a and 122b are respectively connected to liquid outlet
pipes 149a and 149b provided in the copper dissolution tanks 110a
and 110b. Valves AV3-2 and AV4-2 are provided in the branch
circulation pipes 121a and 121b, respectively. Valves AV3-3 and
AV4-3 are provided in the branch circulation pipes 122a and 122b,
respectively.
[0512] Branch circulation pipes 119a and 119b are connected in
communication with the annular spaces 145 of the copper dissolution
tanks 110a and 110b, respectively. Valves AV3-1 and AV4-1 are
provided in the branch circulation pipes 119a and 119b,
respectively. The branch circulation pipes 119a, 119b are connected
to one end of a circulation pipe 119. The other end of the
circulation pipe 119 is branched into branch circulation pipes 119d
and 119e at a branch point B2.
[0513] The valves AV3-1, AV3-2, AV3-3, AV4-1, AV4-2, AV4-3 are
collectively disposed in a copper dissolution tank channel
switching section 153.
[0514] The branch circulation pipe 119d extends into the buffer
container 111 through the piping port formed in the cover 120
(through the cover 120). A valve AV2-2 is provided in the branch
circulation pipe 119d.
[0515] One end of a channel switching pipe 115 is connected to the
circulation pipe 118 at a branch point B3. A valve AV1-4 is
provided at the other end of the channel switching pipe 115. By
opening the valve AV1-4, the liquid can be drained from the other
end of the channel switching pipe 115. The plating liquid transport
pipes P12a and P12b are connected to the channel switching pipe 115
via valves AV1-3 and AV1-2, respectively.
[0516] A valve AV1-1 is provided in the circulation pipe 118
between the buffer container 111 and the branch point B3. A valve
AV1-5, a pump P5 and a flow meter 123 are provided in the
circulation pipe 118 between the branch point B3 and the branch
point B1 in this order from the branch point B3. An emptiness check
sensor 127 is provided on a lateral side of the circulation pipe
118 in the vicinity of the buffer container 111 (between the buffer
container 111 and the branch point B3). The emptiness check sensor
127 is capable of detecting the presence or absence of the liquid
at the height of the emptiness check sensor 127 in the circulation
pipe 118. This makes it possible to determine whether or not the
buffer container 111 is empty.
[0517] The valves AV1-1, AV1-2, AV1-3, AV1-4, AV1-5 are
collectively disposed in an inlet-side main channel switching
section 113.
[0518] The branch circulation pipe 119e is connected to the plating
liquid transport pipe P12b at a branch point B4. A valve AV2-1 is
provided in the branch circulation pipe 119e. The valves AV2-1,
AV2-2 are collectively disposed in an outlet-side main channel
switching section 114.
[0519] A plating liquid flow channel can be switched by means of
the inlet-side main channel switching section 113, the copper
dissolution tank channel switching section 153 and the outlet-side
channel switching section 114.
[0520] The undiluted replacement liquid supplying section 112
includes an undiluted replacement liquid tank 128 containing the
undiluted replacement liquid, and a measure cup 129 for dispensing
a predetermined amount of the undiluted replacement liquid. The
undiluted replacement liquid may be, for example, concentrated
sulfuric acid. The measure cup 129 has a cover 129a, and is
virtually sealed. The measure cup 129 has a bottom having an
inverted cone shape. A liquid outlet port is provided in a center
portion of the bottom of the measure cup 129. That is, the bottom
of the measure cup 129 is inclined downward toward the liquid
outlet port. An undiluted replacement liquid transport pipe 130
extends from an upper portion of the measure cup 129 into a bottom
portion of the undiluted replacement liquid tank 128. A valve AV6-3
is provided in the undiluted replacement liquid transport pipe
130.
[0521] The undiluted replacement liquid supplying section 112 is
connected to the buffer container 111 by an undiluted replacement
liquid supply pipe 124. The undiluted replacement liquid supply
pipe 124 extends to the upper portion of the measure cup 129
through the cover 129a. One end of an undiluted replacement liquid
transport pipe 131 is connected to the center portion of the bottom
(liquid outlet port) of the measure cup 129. The other end of the
undiluted replacement liquid transport pipe 131 is connected to the
undiluted replacement liquid supply pipe 124 at a branch point B5.
A valve AV6-1 is provided in the undiluted replacement liquid
supply pipe 124 between the branch point B5 and the measure cup
129. A valve AV6-2 is provided in the undiluted replacement liquid
transport pipe 131.
[0522] A leak pipe 132 extends through the cover 129a to be
connected in communication with the measure cup 129. A valve AV6-4
is provided in the leak pipe 132 outside the measure cup 129. By
opening the valve AV6-4, the internal pressure of the measure cup
is set at the atmospheric pressure.
[0523] A constant volume check sensor 133 is provided at a
predetermined height on a lateral side of the measure cup 129 for
detecting the presence or absence of liquid at this predetermined
height in the measure cup 129. An emptiness check sensor 134 is
provided on a lateral side of the undiluted replacement liquid
transport pipe 131 in the vicinity of the measure cup 129. The
emptiness check sensor 134 is capable of detecting the presence or
absence of liquid at the height of the emptiness check sensor 134
in the undiluted replacement liquid transport pipe 131. This makes
it possible to determine whether or not the measure cup 129 is
empty.
[0524] A deionized water supply pipe 135 extends through the cover
120 to be connected in communication with the buffer container 111.
Thus, deionized water can be supplied to the buffer container 111
from a deionized water supply source not shown. A valve AV7-1 is
provided in the deionized water supply pipe 135.
[0525] An air inlet/outlet pipe 136 is introduced into the buffer
container 111 through the cover 120. An air pump 137 is connected
to an end of the air inlet/outlet pipe 136 opposite from the buffer
container 111. A three-way valve AV8-3 is provided in the air
inlet/outlet pipe 136. The three-way valve AV8-3 is adapted to
selectively establish air communication between the buffer
container 111 and the air pump 137 and between the buffer container
111 and the atmosphere.
[0526] The air pump 137 has an air exhaustion pipe 138 and an air
supply pipe 139. The air inlet/outlet pipe 136 is connected in
communication with the air exhaustion pipe 138 and the air supply
pipe 139. A three-way valve AV8-1 is provided in the air exhaustion
pipe 138, while a three-way valve AV8-2 is provided in the air
supply pipe 139. The three-way valves AV8-1, AV8-2, AV8-3, which
may be air valves, are collectively disposed in a pressure
increasing/reducing section 164.
[0527] Air can be supplied into the buffer container 111 by
establishing communication between the atmosphere and the air pump
137 by the three-way valve AV8-1 and between the air pump 137 and
the air inlet/outlet pipe 136 by the three-way valve AV8-2, and
actuating the air pump 137. Gas can be exhausted from the buffer
container 111 by establishing communication between the air
inlet/outlet pipe 136 and the air pump 137 by the three-way valve
AV8-1 and between the air pump 137 and the atmosphere by the
three-way valve AV8-2, and actuating the air pump 137.
[0528] The opening and closing of the valve AV7-1 and the valves in
the inlet-side main channel switching section 113, the outlet-side
main channel switching section 114, the copper dissolution tank
channel switching section 153, the undiluted replacement liquid
supplying section 112 and the pressure increasing/reducing section
164, and the operations of the pump P5 and the air pump 137 are
controlled by the system controller 155 of the wafer treating
section 1 via the serial/parallel converter 165. Output signals of
the constant volume check sensors 126, 133, the emptiness check
sensors 127, 134, the flow meter 123 and the weight meters 154a,
154b are inputted to the system controller 155 of the wafer
treating section 1 via the serial/parallel converter 165.
[0529] With reference to FIG. 26, an explanation will hereinafter
be given to the operation of the major constituent managing section
2 during the plating process performed in the plating section
12.
[0530] Prior to the plating process, the system controller 155
determines which of the copper dissolution tanks 110a, 110b is to
be used. One of the copper dissolution tanks 110a, 110b which
contains the copper tubes 146 whose total weight is lightest is
used. The other copper dissolution tank is not used, but reserved
as a spare.
[0531] The storage device 155M of the system controller 155 stores
data of the net weights of the respective copper dissolution tanks
110a, 110b and the weights of the respective copper dissolution
tanks 110a, 110b measured when the plating liquid is filled
therein. The system controller 155 calculates the weights of the
copper tubes 146 in the copper dissolution tanks 110a, 110b on the
basis of the output signals of the weight meters 154a, 154b.
[0532] It is herein assumed that the weight of the copper tubes 146
in the copper dissolution tank 110a is judged to be the lightest
and sufficient to supply copper ions to the plating liquid for a
predetermined period. In this case, a flow channel is established
for circulating the plating liquid through the plating section 12
and the copper dissolution tank 110a under the control of the
system controller 155. More specifically, the valves AV1-3, AV1-5,
AV3-2, AV3-1, AV2-1 are opened, and the other valves are
closed.
[0533] In this state, the pump P5 is actuated under the control of
the system controller 155. Thus, the plating liquid is supplied
into the copper dissolution tank 110a from the plating section 12,
flows over the interior and exterior surfaces of the copper tubes
146 in the copper dissolution tank 110a, and returned into the
plating section 12. In the copper dissolution tank 110a, the copper
tubes 146 are deprived of electrons by trivalent iron ions in the
plating liquid, whereby the trivalent iron ions are reduced to
divalent iron ions. Copper ions are leached into the plating liquid
from the copper tubes 146 deprived of the electrons.
[0534] Thus, the copper ions are supplied from the copper tubes
146, while being consumed on the lower surface of the wafer W
during the plating process. On the other hand, the trivalent iron
ions are reduced to the divalent iron ions in the vicinity of the
copper tubes 146, while the divalent iron ions are oxidized into
trivalent iron ions in the vicinity of the anode 76.
[0535] Where the concentrations of the copper ions, the divalent
iron ions and the trivalent iron ions in the plating liquid are not
within the predetermined concentration ranges, the plating process
cannot properly be performed with a poorer capability of filling
the holes or grooves formed in the surface of the wafer W with
copper. Therefore, the concentrations of the copper ions and the
divalent and trivalent iron ions in the plating liquid should be
kept at the predetermined concentration levels (within the
predetermined concentration ranges). That is, the amount of the
copper ions consumed on the lower surface of the wafer W should
substantially be equalized with the amount of the copper ions
leaching out of the copper tubes 146, and the amount of the
divalent iron ions occurring in the vicinity of the anode 76 should
substantially be equalized with the amount of the trivalent iron
ions occurring in the vicinity of the copper tubes 146.
[0536] The copper ion consumption rate at which the copper ions are
consumed in the plating liquid by the plating is determined by the
operation statuses of the respective plating units 20a to 20d. The
copper ion leaching rate at which the copper ions leach into the
plating liquid from the copper tubes 146 in the copper dissolution
tank 110a is determined by the surface area of the copper tubes 146
in contact with the plating liquid, the flow rate of the plating
liquid flowing in the vicinity of the copper tubes 146 and the
concentration of the trivalent iron ions in the plating liquid.
[0537] The inner and outer peripheral surface areas of the copper
tube 146 account for a major percentage of the total surface area
of the cupper tube 146. As the dissolution of the copper tube 146
proceeds, the thickness and length of the copper tube 146 are
reduced. However, the reduction rate of the length is negligible.
Therefore, the outer and inner peripheral surface areas of the
copper tube 146 (the total surface area of the copper tube 146) are
considered to be virtually constant before complete dissolution of
the copper tube 146, even if the dissolution of the copper tube 146
proceeds. Whether or not the copper tube 146 is very close to the
complete dissolution is determined on the basis of the output
signal of the weight meter 154a. The flow rate of the plating
liquid flowing into the copper dissolution tank 11a may be employed
as the flow rate of the plating liquid flowing in the vicinity of
the copper tube 146.
[0538] Therefore, the system controller 155 determines the pumping
rate of the pump P5 on the basis of the operation statuses of the
plating units 20a to 20d and the output signal of the
absorptiometer 66B indicative of the concentration of the iron
ions. The pumping rate of the pump P5 is regulated at a
predetermined level on the basis of the feedback of the output
signal of the flow meter 123 to the system controller 155. Under
such control, the amount of the copper ions supplied to the plating
liquid is balanced with the amount of the copper ions consumed in
the plating liquid to keep the copper ion concentration virtually
constant in the plating liquid.
[0539] If the dissolution of the copper tubes 146 in the copper
dissolution tank 110a extremely proceeds, the total surface area of
the copper tubes 146 is rapidly reduced, making it difficult to
supply the copper ions to the plating liquid at a constant rate. To
avoid such an event, the supply of the plating liquid to the copper
dissolution tank 110a is stopped when the weight of the copper
tubes 146 in the copper dissolution tank 110a is reduced below a
predetermined level (e.g., 20% to 30% of the initial weight). Then,
the supply of the plating liquid to the copper dissolution tank
110b is started.
[0540] More specifically, when the system controller 155 judges on
the basis of the signal of the weight meter 154a that the weight of
the copper tubes 146 in the copper dissolution tank 110a is reduced
below the predetermined level, the valves AV4-1 and AV4-2 are
opened and the valves AV3-1 and AV3-2 are closed under the control
of the system controller 155. Thus, the plating liquid is
circulated through the plating section 12 and the copper
dissolution tank 110b. Where the copper tubes 146 contained in the
copper dissolution tank 110b has a sufficient weight, the copper
ions can stably be supplied into the plating liquid.
[0541] Since the two copper dissolution tanks 110a, 110b are
provided in the major constituent managing section 2, the copper
ions can constantly be supplied to the plating liquid without
excess and deficiency. Thus, the surface of the wafer W can
properly be copper-plated with the fine holes or grooves thereof
properly filled with copper.
[0542] A copper plate or a copper mesh may be accommodated instead
of the copper tube 146 as the copper supply source in the copper
dissolution tank 110a, 110b.
[0543] Next, an explanation will be given to the operation of the
major constituent managing section 2 after the completion of the
plating process in the plating section 12. If the plating liquid is
circulated through the plating liquid container 55 and the copper
dissolution tank 110a or 110b when the plating process is not
performed in any of the plating units 20a to 20d, the concentration
of the copper ions in the plating liquid is increased beyond the
proper concentration range. This is because the copper ions are
continuously supplied to the plating liquid from the copper tubes
146, though the copper ions are not consumed.
[0544] If the circulation of the plating liquid is stopped, the
surface of the copper tubes 146 in the copper dissolution tank
110a, 110b is irreversibly deteriorated. Therefore, the surface of
the wafer W cannot properly be copper-plated with a poorer
capability of filling the fine holes or grooves thereof with
copper, when the plating process is performed again in any of the
plating units 20a to 20d by resuming the circulation of the plating
liquid.
[0545] To cope with this, the plating liquid in the copper
dissolution tank 110a, 110b is replaced with the replacement liquid
for prevention of the increase in the concentration of the copper
ions in the plating liquid and the deterioration of the surface of
the copper tubes 146 upon the completion of the plating process in
the plating section 12. It is herein assumed that the plating
liquid in the copper dissolution tank 110a is replaced with the
replacement liquid.
[0546] The deterioration of the surface of the copper tubes 146 may
occur within several hours. On the other hand, the plating process
is often resumed immediately after the completion of the plating
process in the plating section 12 due to a change in a production
plan. In this case, if the plating liquid in the copper dissolution
tank 110a is already replaced with the replacement liquid, the
replacement liquid in the copper dissolution tank 110a should be
replaced again with the plating liquid. The time required for the
replacement of the plating liquid in the copper dissolution tank
110a is about 5 minutes to about 10 minutes, so that the
productivity is reduced. Therefore, the plating liquid in the
copper dissolution tank 110a is replaced with the replacement
liquid after a lapse of a 2- to 3-hour standby period from the
completion of the plating process in the plating section 12.
[0547] If the plating process is less likely to be resumed
immediately after the completion of the plating process in the
plating section 12, the plating liquid in the copper dissolution
tank 110a may be replaced with the replacement liquid immediately
after the completion of the plating process.
[0548] First, the pump P5 is stopped and all the valves in the
major constituent managing section 2 are closed under the control
of the system controller 155. In turn, the system controller 155
controls the pressure increasing/reducing section 164 to supply air
into the buffer container 111. Thus, the internal pressure of the
buffer container 111 is increased.
[0549] Then, the valves AV2-2, AV3-1, AV3-2, AV1-5, AV1-2 are
opened under the control of the system controller 155. Thus, air
pressurized in the buffer container 111 is introduced into the
annular space 145, so that the plating liquid is forced out of the
copper dissolution tank 110a into the plating liquid container 55
in the plating section 12.
[0550] The system controller 155 calculates the weight of the
plating liquid in the copper dissolution tank 110a on the basis of
the output signal of the weight meter 154a, and maintains the
aforesaid conditions until it is judged that almost all the plating
liquid is expelled from the copper dissolution tank 110a. When the
system controller 155 judges that almost all the plating liquid is
expelled from the copper dissolution tank 110a, the valve AV3-3 is
opened for a predetermined period under the control of the system
controller 155. Thus, the plating liquid remaining in the bottom
portion of the copper dissolution tank 11a is virtually completely
discharged through the liquid outlet pipe 149a.
[0551] Subsequently, the valve AV7-1 is opened under the control of
the system controller 155 to introduce deionized water into the
buffer container 111. When it is judged on the basis of the output
signal of the constant volume check sensor 126 that the surface of
deionized water rises to reach the predetermined level in the
buffer container 111, the valve AV7-1 is closed under the control
of the system controller 155. Thus, a predetermined amount of
deionized water is contained in the buffer container 111.
[0552] In turn, the valves in the major constituent managing
section 2 except the three-way valves AV8-1, AV8-2, AV8-3 are
closed, and air is exhausted from the buffer container 111 by the
pressure increasing/reducing section 164 under the control of the
system controller 155. Thus, the internal pressure of the buffer
container 111 is reduced. Then, the valves AV6-1, AV6-3 are opened
under the control of the system controller 155. Thus, the internal
pressure of the measure cup 129 is also reduced, so that the
undiluted replacement liquid is sucked into the measure cup 129
from the undiluted replacement liquid tank 128 through the
undiluted replacement liquid transport pipe 130.
[0553] During this period, the system controller 155 monitors the
output signal of the constant volume check sensor 133, and judges
whether the surface of the undiluted replacement liquid in the
measure cup 129 reaches the predetermined level. If it is judged
that the surface of the undiluted replacement liquid reaches the
predetermined level, the valves AV6-3, AV6-1 are closed under the
control of the system controller 155. Thus, a predetermined volume
of the undiluted replacement liquid is dispensed in the measure cup
129.
[0554] Then, the valves AV6-2, AV6-4 are opened under the control
of the system controller 155. Thus, the internal pressure of the
measure cup 129 is set at the atmospheric pressure, so that the
undiluted replacement liquid is transported from the measure cup
129 into the buffer container 111 having a lower internal pressure
through the undiluted replacement liquid transport pipe 131 and the
undiluted replacement liquid supply pipe 124 and mixed with the
deionized water in the buffer container 111.
[0555] Since the bottom of the measure cup 129 is inclined downward
toward the undiluted replacement liquid transport pipe 131 (liquid
outlet port), the undiluted replacement liquid is virtually
completely discharged from the measure cup 129. When it is judged
on the basis of the output signal of the emptiness check sensor 134
that the measure cup 129 is empty, the valves AV6-2, AV6-4 are
closed under the control of the system controller 155.
[0556] Thus, the replacement liquid which has a predetermined
composition and a predetermined concentration (e.g., 10% sulfuric
acid aqueous solution) is prepared in the buffer container 111.
[0557] In turn, the system controller 155 controls the three-way
valve AV8-3 to establish communication between the buffer container
111 and the atmosphere. Thus, the internal pressure of the buffer
container 111 is set at the atmospheric pressure. Thereafter, the
valves AV1-1, AV1-5, AV3-2, AV3-1, AV2-2 are opened, and the pump
P5 is actuated under the control of the system controller 155. At
this time, the pump P5 is operated only for a predetermined period,
or operated until it is judged on the basis of the output signal of
the weight meter 154a that the copper dissolution tank 110a is
filled with the replacement liquid.
[0558] Thereafter, the pump P5 is stopped, and all the valves in
the major constituent managing section 2 are closed under the
control of the system controller 155. Then, the valves AV1-1, AV1-4
are opened under the control of the system controller 155, whereby
the replacement liquid remaining in the buffer container 111 is
drained. Thus, the replacement of the plating liquid in the copper
dissolution tank 110a with the replacement liquid is completed.
[0559] Thus, the increase in the copper ion concentration of the
plating liquid can be prevented. Further, the deterioration of the
surface of the copper tube 146 can be prevented. Therefore, when
the plating process is performed again in any of the plating units
20a to 20d by circulating the plating liquid through the plating
section 12 and the copper dissolution tank 110a (110b), the surface
of the wafer W can properly be copper-plated with the fine holes
and grooves thereof properly filled with copper. Even if a small
amount of the replacement liquid of the sulfuric acid aqueous
solution is mixed in the plating liquid, the replacement liquid
does not adversely affect the plating liquid because sulfuric acid
is a supporting electrolyte of the plating liquid.
[0560] In the replacement of the plating liquid with the
replacement liquid, deionized water may be introduced into and
discharged from the copper dissolution tank 110a before the
introduction of the replacement liquid after the plating liquid is
discharged from the copper dissolution tank 110a. Thus, the copper
dissolution tank 110a is cleaned with deionized water, so that the
amount of the plating liquid mixed with the replacement liquid can
be reduced. The introduction of the deionized water into the copper
dissolution tank 110a can be achieved in substantially the same
manner as the introduction of the replacement liquid into the
copper dissolution tank 110a, except that only deionized water is
introduced into the buffer container 111 from the deionized water
supply source (but the undiluted replacement liquid is not
introduced after the introduction of the deionized water).
[0561] Where the replacement liquid filled in the copper
dissolution tank 110a, 110b is replaced again with the plating
liquid, the following operation is performed. First, the
replacement liquid is expelled from the copper dissolution tank
110a, 110b in substantially the same manner as when the plating
liquid is expelled from the copper dissolution tank 110a, 110b for
the replacement of the plating liquid with the replacement liquid.
In this operation, however, the expelled replacement liquid is
drained by closing the valve AV1-2 and opening the valve AV1-4
under the control of the system controller 155.
[0562] Thereafter, all the valves in the major constituent managing
section 2 are closed, and then the valves AV1-2, AV1-5, AV3-2,
AV3-1, AV2-1, for example, are opened under the control of the
system controller 155. Thus, the plating liquid is introduced into
the copper dissolution tank 110a.
[0563] Next, an explanation will be given to the construction and
function of the minor constituent managing section 3. FIG. 27 is a
schematic diagram illustrating the construction of the analyzing
cup provided in the minor constituent managing section 3.
[0564] The minor constituent managing section 3 includes a sampling
section 319, and a plating liquid transport pipe 330 extends
between the sampling section 319 and the analyzing cup 336. The
plating liquid is transported from the plating liquid container 55
(see FIG. 7) provided in the wafer treating section 1 into the
sampling section 319 through the sampling pipe 322, and then
dispensed in a predetermined amount into the analyzing cup 336
through the plating liquid transport pipe 330. The analyzing cup
336 has a volume of about 50 ml to about 200 ml.
[0565] The analyzing cup 336 has an open top. A nozzle 330N is
connected to an end of the plating liquid transport pipe 330 on the
side of the analyzing cup 336. The nozzle 330N is disposed in an
upper portion of the analyzing cup 336. The plating liquid
transported from the sampling section 319 can be supplied into the
analyzing cup 336 through the nozzle 330N.
[0566] A plating accelerating additive (hereinafter referred to as
"accelerator"), a plating retarding additive (hereinafter referred
to be "retarder") and a base liquid for diluting the plating liquid
to be analyzed are used in the minor constituent managing section
3. The minor constituent managing section 3 includes a reagent
supplying section 313 which is adapted to accommodate the
accelerator, the retarder and the base liquid as analytic reagents
and supply these reagents to the analyzing cup 336.
[0567] An accelerator transport pipe 351, a retarder transport pipe
352 and a base liquid transport pipe 353 extend from the reagent
supplying section 313 to the analyzing cup 336. Nozzles 351N, 352N
and 353N are respectively connected to ends of the accelerator
transport pipe 351, the retarder transport pipe 352 and the base
liquid transport pipe 353 on the side of the analyzing cup 336. The
nozzles 351N, 352N and 353N are disposed in the upper portion of
the analyzing cup 336. The accelerator, the retarder and the base
liquid can be supplied into the analyzing cup 336 through the
nozzles 351N, 352N and 353N, respectively.
[0568] A deionized water pipe 356 extends from the deionized water
source to the analyzing cup 336. A valve 356V is provided in the
deionized water pipe 356. A nozzle 356N provided in the upper
portion of the analyzing cup 336 is connected to the deionized
water pipe 356. By opening the valve 356V, deionized water can be
supplied into the analyzing cup 336 through the nozzle 356N.
[0569] The nozzles 330N, 351N, 352N, 353N and 356N are each located
at such a height as to be kept out of contact with liquid contained
in the analyzing cup 336. The nozzles 330N, 351N, 352N, 353N and
356N each have an open diameter of 0.1 mm to 1 mm. Thus, very small
amounts of the plating liquid, the accelerator, the retarder, the
base liquid and deionized water can be supplied dropwise into the
analyzing cup 336.
[0570] The analyzing cup 336 has a funnel-shaped bottom portion
downwardly tapered. A drain port 336h is provided at the lowest
portion of the analyzing cup 336. That is, the bottom portion of
the analyzing cup 336 is inclined downward toward the drain port
336h. A drain pipe 344 is connected to the drain port 336h, and a
valve 344V is provided in the drainpipe 344. By opening the valve
344V, the liquid in the analyzing cup 336 can be drained. Since the
bottom portion of the analyzing cup 336 is inclined downward toward
the drain port 336h (drain pipe 344), the liquid in the analyzing
cup 336 can virtually completely be drained.
[0571] A rotary electrode 308, a counter electrode 309 and a
reference electrode 310 are inserted in the analyzing cup 336. The
counter electrode 309 and the reference electrode 310 each have a
rod shape, and are disposed generally vertically.
[0572] The rotary electrode 308 is composed of platinum (Pt), and
exposed from one end of a cylindrical rod 308a of an insulative
material. The rotary electrode 308 has a mirror-finished exposed
portion. The rod 308a is disposed vertically with the rotary
electrode 308 facing downward. The rod 308a is held rotatably about
a center axis thereof by a holder not shown.
[0573] An electrically conductive member 308b extends through the
rod 308a along the center axis of the rod 308a. One end of the
electrically conductive member 308b is electrically connected to
the rotary electrode 308. The other end of the electrically
conductive member 308b projects from the rod 308a, and a rotary
connector 312 is attached to the projection. A rotary terminal of
the rotary connector 312 is electrically connected to the
electrically conductive member 308b, while a stationary terminal of
the rotary connector 312 is electrically connected to a
potentiostat 172 via a conduction line.
[0574] A pulley 315 is fitted around an end portion of the rod 308a
adjacent to the rotary connector 312. A pulley 317 fitted around a
rotation shaft of a motor 316 is disposed on a lateral side of the
pulley 315. A belt 318 is stretched between the pulley 315 and the
pulley 317. By driving the motor 316, the rotary electrode 308 can
be rotated about the center axis of the rod 308a.
[0575] The counter electrode 309 is composed of copper, and
electrically connected to the potentiostat 172 via a conduction
line.
[0576] The reference electrode 310 includes an outer glass tube
310a, an inner glass tube 310b provided in the outer glass tube
310a, and a silver/silver chloride electrode 310c provided in the
inner glass tube 310b. The inside of the inner glass tube 310b
slightly communicates with the outside of the outer glass tube
310a. The silver/silver chloride electrode 310c is electrically
connected to the potentiostat 172 and the minor constituent
management controller 169 via conduction lines.
[0577] A sweep voltage specified by the minor constituent
management controller 169 is applied to the potentiostat 172. The
potentiostat 172 regulates an electric current flowing between the
counter electrode 309 and the rotary electrode 308 so that a
voltage between the reference electrode 310 and the rotary
electrode 308 (action electrode) is equalized with the sweep
voltage. A voltage (signal) indicative of an electric current level
observed at this time is applied to the minor constituent
management controller 169.
[0578] The opening and closing of the valves 356V, 344V and the
operation of the motor 316 are controlled by the minor constituent
management controller 169.
[0579] The concentrations of the accelerator and the retarder in
the plating liquid can be measured in the analyzing cup 336. An
explanation will be given to how to measure the concentration of
the accelerator or the retarder in the plating liquid through the
CVS analysis.
[0580] First, a predetermined amount of the plating liquid is
transported from the sampling section 319 into the analyzing cup
336 through the plating liquid transport pipe 330. Then, the minor
constituent management controller 169 controls the motor 316 to
rotate the rotary electrode 308 about the axis of the rod 308a.
[0581] In turn, the minor constituent management controller 169
controls the potentiostat 172 to cause the sweep voltage to
fluctuate in a predetermined cycle. Thus, the deposition and
removal (stripping) of copper with respect to the rotary electrode
308 (action electrode) cyclically occur. The electric current
flowing through the rotary electrode 308 when copper deposited on
the rotary electrode 308 is stripped has a certain correlation with
the concentration of the accelerator or the retarder in the plating
liquid. Therefore, the concentration of the accelerator or the
retarder can be determined by monitoring the electric current
flowing through the rotary electrode 308 by the minor constituent
management controller 169.
[0582] The accelerator, the retarder and the base liquid are each
added in a predetermined amount to the plating liquid in the
analyzing cup 336 as required during the analysis.
[0583] After completion of the CVS analysis, the minor constituent
management controller 169 calculates the amount of the accelerator
or the retarder to be added to the plating liquid on the basis of
the calculated accelerator concentration or retarder concentration
so that the concentration of the accelerator or the retarder in the
plating liquid in the plating section 12 can be kept within a
predetermined concentration range. The minor constituent managing
section 3 includes a replenishment section not shown for
additionally supplying the accelerator and the retarder into the
plating liquid container 55 provided in the plating section 12. The
minor constituent management controller 169 controls the
replenishment section to supply the retarder or the accelerator in
the calculated amount into the plating liquid in the plating liquid
container 55 through the replenishment pipe 324.
[0584] The minor constituent managing section 3 is not necessarily
required to include the replenishment section. In this case, the
operator may manually add a replenishment liquid in a required
amount to the plating liquid contained in the plating liquid
container 55.
[0585] Next, an explanation will be given to the construction and
function of the post-treatment agent supplying section 4. FIG. 28
is a schematic perspective view illustrating the construction of
the post-treatment agent supplying section 4.
[0586] The post-treatment agent supplying section 4 includes a
post-treatment agent tank 290 which contains the post-treatment
agent (e.g., the etching liquid and the cleaning liquid) to be used
in the bevel etching units 21a, 21b and the cleaning units 22a,
22b, and a tank enclosure 291 which houses the post-treatment agent
tank 290. In this embodiment, only the single post-treatment agent
tank 290 is shown, assuming that the same agent is employed as the
etching liquid for use in the bevel etching units 21a, 21b and as
the cleaning liquid for use in the cleaning units 22a, 22b. Where a
plurality of post-treatment agents are used, a plurality of
post-treatment agent tanks 290 may be employed.
[0587] The tank enclosure 291 has a top cover 293 and a front door
294. By opening the cover 293 or the door 294, the post-treatment
agent tank 290 can be taken in and out of the tank enclosure 291.
With the cover 293 and the door 294 being closed, the tank
enclosure 291 is virtually sealed.
[0588] A vat 292 is provided on the bottom of the tank enclosure
291, and the post-treatment agent tank 290 is placed in the vat
292. The volume of the vat 292 is greater than the volume of the
post-treatment agent tank 290 (where the plurality of
post-treatment agent tanks 290 are provided, the total volume of
the post-treatment agent tanks 290). Even if the post-treatment
agent is entirely leaked out of the post-treatment agent tank 290,
the leaked post-treatment agent can be received in the vat 292.
[0589] An air outlet port 295 and a post-treatment agent pipe
introduction port 296 are provided in a rear face of the tank
enclosure 291. An air outlet pipe 297 is connected to the air
outlet port 295 for exhausting air from the tank enclosure 291. By
exhausting air through the air outlet pipe 297 with the tank
enclosure 291 being virtually sealed, the internal pressure of the
tank enclosure 291 can be kept at a negative level.
[0590] A short protection pipe 298 is inserted through the
post-treatment agent pipe introduction port 296, and the
post-treatment agent pipe P14 is inserted through the protection
pipe 298. That is, the two pipes are inserted through the
post-treatment agent pipe introduction port 296.
[0591] The post-treatment agent pipe P14 extends from an inside
bottom portion of the post-treatment agent tank 290 to each of the
bevel etching units 21a, 21b and the cleaning units 22a, 22b. The
valve 93V (see FIG. 23) and the valve 108V (see FIG. 24) provided
in the post-treatment agent pipe P14 are disposed in the
post-treatment agent supplying section 4 (though not shown in FIG.
28). By actuating a pump not shown with the valve 93V or 108V being
open, the post-treatment agent (the etching liquid or the cleaning
liquid) can be supplied into the bevel etching units 21a, 21b or
the cleaning units 22a, 22b from the post-treatment agent tank
290.
[0592] FIG. 29 is a block diagram illustrating the construction of
control systems for the major constituent managing section 2, the
minor constituent managing section 3 and the post-treatment agent
supplying section 4.
[0593] The major constituent managing section 2 includes the
serial/parallel converter 165 and an operation panel 166. The
system controller 155 provided in the wafer treating section 1 is
connected to the serial/parallel converter 165 via the RS-485
compatible serial port by a cable, and connected to the operation
panel 166 via the RS-232C compatible serial port by a cable.
[0594] Electromagnetic valves 167 and sensors 168 (e.g., the
constant volume check sensors 126, 133, the emptiness check sensors
127, 134 and the weight meters 154a, 154b (see FIG. 26)) are
connected in parallel to the serial/parallel converter 165. The
electromagnetic valves 167 are capable of controlling air valves
(e.g., the valve AV1-1 and the like (see FIG. 26)). The operator
can input and output information on the major constituent managing
section 2 by means of the operation panel 166.
[0595] The minor constituent managing section 3 includes the minor
constituent management controller 169, so that a control operation
can be performed independently of the system controller 155
provided in the wafer treating section 1. The minor constituent
management controller 169 is connected to the system controller 155
via the RS-232C compatible serial port by a cable.
[0596] A display 170, a keyboard 171, an audible alarm generator
400, the potentiostat (power source) 172, a syringe pump 173 and a
serial/parallel converter 174 are connected to the minor
constituent management controller 169. The display 170 and the
keyboard 171 permit the operator to interact with the minor
constituent management controller 169 for inputting and outputting
information.
[0597] The syringe pump 173 is capable of adding the analytic
reagents dropwise to the plating liquid contained in the analyzing
cup 336 when the concentrations of the minor constituents of the
plating liquid are measured. Further, the syringe pump 173 is
capable of quantitatively dispensing replenishment liquids
respectively containing the minor constituents in amounts to be
added to the plating liquid in the plating section 12.
[0598] Electromagnetic valves 175 and sensors 176 (e.g., surface
level sensors provided on containers for quantitatively dispensing
the reagents and the like) are connected to the serial/parallel
converter 174 by parallel cables. The electromagnetic valves 175
are capable of controlling air valves. The serial/parallel
converter 174 converts serial signals from the minor constituent
management controller 169 into parallel signals, which are in turn
outputted to the electromagnetic valves 175 and the like. Further,
the serial/parallel converter 174 converts parallel signals from
the sensors 176 into serial signals, which are in turn outputted to
the minor constituent management controller 169.
[0599] The post-treatment agent supplying section 4 includes a
serial/parallel converter 177. The system controller 155 provided
in the wafer treating section 1 is connected to the serial/parallel
converter 177 via the RS-485 compatible serial port by a cable.
Electromagnetic valves 178 and sensors 179 are connected to the
serial/parallel converter 177 by parallel cables. The
electromagnetic valves 178 are capable of controlling air valves
(e.g., the valve 93V (see FIG. 23) and the valve 108V (see FIG.
24)). The sensors 179 include a liquid surface sensor attached to
the post-treatment agent tank 290, an air exhaustion pressure
sensor for measuring an air exhaustion pressure in the air outlet
pipe 297, and a leakage detection sensor provided in the vat 292
for detecting leakage of the post-treatment agent and the like.
[0600] While the present invention has been described in detail by
way of the embodiment thereof, it should be understood that the
foregoing disclosure is merely illustrative of the technical
principles of the present invention but not limitative of the same.
The spirit and scope of the present invention are to be limited
only by the appended claims.
[0601] This application corresponds to Japanese Patent Application
No. 2003-12681 filed with the Japanese Patent Office on Jan. 21,
2003, the disclosure of which is incorporated herein by
reference.
* * * * *