U.S. patent application number 12/453347 was filed with the patent office on 2009-09-03 for plating apparatus.
Invention is credited to Masaaki Kimura, Rei Kiumi, Fumio Kuriyama, Nobutoshi Saito, Takashi Takemura, Toshikazu Yajima.
Application Number | 20090218231 12/453347 |
Document ID | / |
Family ID | 30767712 |
Filed Date | 2009-09-03 |
United States Patent
Application |
20090218231 |
Kind Code |
A1 |
Yajima; Toshikazu ; et
al. |
September 3, 2009 |
Plating apparatus
Abstract
A plating apparatus according to the present invention has a
plating tank for holding a plating solution, an anode disposed so
as to be immersed in the plating solution in the plating tank, a
regulation plate disposed between the anode and a plating workpiece
disposed so as to face the anode, and a plating power supply for
supply a current between the anode and the plating workpiece to
carry out plating. The regulation plate is disposed so as to
separate the plating solution held in the plating tank into a
plating solution on the anode side and a plating solution on the
plating workpiece side, and a through-hole group having a large
number of through-holes is formed in the regulation plate.
Inventors: |
Yajima; Toshikazu; (Tokyo,
JP) ; Takemura; Takashi; (Tokyo, JP) ; Kiumi;
Rei; (Tokyo, JP) ; Saito; Nobutoshi; (Tokyo,
JP) ; Kuriyama; Fumio; (Tokyo, JP) ; Kimura;
Masaaki; (Tokyo, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
1030 15th Street, N.W.,, Suite 400 East
Washington
DC
20005-1503
US
|
Family ID: |
30767712 |
Appl. No.: |
12/453347 |
Filed: |
May 7, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10485350 |
Aug 19, 2004 |
|
|
|
PCT/JP03/09144 |
Jul 18, 2003 |
|
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12453347 |
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Current U.S.
Class: |
205/96 ;
205/148 |
Current CPC
Class: |
C25D 7/123 20130101;
C25D 17/008 20130101; C25D 17/001 20130101; C25D 17/002 20130101;
C25D 21/12 20130101 |
Class at
Publication: |
205/96 ;
205/148 |
International
Class: |
C25D 21/10 20060101
C25D021/10; C25D 5/00 20060101 C25D005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2002 |
JP |
2002-210097 |
Claims
1-26. (canceled)
27. A method for plating a workpiece, comprising: disposing a
plating workpiece vertically in a plating tank so as to be immersed
in 5 a plating solution in said plating tank; disposing an anode
vertically in said plating tank so as to be immersed in the plating
solution in said plating tank and face the plating workpiece;
disposing a regulating plate vertically between the workpiece and
said anode so as to separate the plating solution held in said
plating tank into a plating solution on said 10 anode side and a
plating solution on the plating workpiece side; and supplying a
current between said anode and the plating workpiece to carry out
plating while agitating the plating solution on the workpiece side
and regulating an electric filed in said plating tank, which is
produced between said anode and the plating workpiece, by the
regulation plate.
28. The method according to claim 27, wherein said electric filed
in said plating tank is regulated by promoting leakage of said
electric filed through a large number of through-holes provided in
said regulation plate while preventing the plating solution from
passing through said through-holes, thereby spreading the leaked
electric filed uniformly.
29. The method according to claim 28, wherein said through holes
are formed in a circular area corresponding to the shape of the
workpiece so as to form the through-hole group.
30. The method according to claim 27, wherein said electric field
in said plating tank is regulated by passing said electric filed
uniformly through a cylindrical member connected to a surface of
said regulation plate continuously with a hole formed in said
regulation plate.
31. The method according to claim 30, wherein said hole has an
inside diameter corresponding approximately to an outside diameter
of a surface of the plating workpiece.
32. The method according to claim 30, wherein said cylindrical
member has an inside diameter corresponding approximately to an
outside diameter of a surface of the plating workpiece.
33. The method according to claim 27, further comprising: supplying
the plating solution into said plating tank from a bottom of said
plating tank while allowing the plating solution to overflow an
upper end of an overflow weir of said plating tank.
34. The method according to claim 27, wherein said agitating of the
plating 15 solution is performed by reciprocating a paddle in
parallel to the plating workpiece.
35. The method according to claim 28, further comprising: supplying
the plating solution into said plating tank from a bottom of said
plating tank while allowing the plating solution to overflow an
upper end of an overflow weir of said plating tank.
36. The method according to claim 30, further comprising: supplying
the plating solution into said plating tank from a bottom of said
plating tank while allowing the plating solution to overflow an
upper end of an overflow weir of said plating tank.
37. The method according to claim 28, wherein said agitating of the
plating solution is performed by reciprocating a paddle in parallel
to the plating workpiece.
38. The method according to claim 30, wherein said agitating of the
plating solution is performed by reciprocating a paddle in parallel
to the plating workpiece.
Description
[0001] This application is a divisional of U.S. application Ser.
No. 10/485,350, filed Aug. 19, 2004, which is a national stage
application of International application No. PCT/JP03/09144, filed
Jul. 18, 2003.
TECHNICAL FIELD
[0002] The present invention relates to a plating apparatus for
carrying out plating of a surface of a plating workpiece to be
plated, such as a substrate, and more particularly to a plating
apparatus for forming a plated film in fine interconnect trenches
or holes, via holes, through-holes, or resist openings formed in a
surface of a semiconductor wafer or the like, or for forming a bump
(protruding electrode), which provides electrical connection with
an electrode of a package or the like, on a surface of a
semiconductor wafer.
BACKGROUND ART
[0003] In TAB (Tape Automated Bonding) or FC (Flip Chip), for
example, it has widely been practiced to form protruding connecting
electrodes (bumps) of gold, copper, solder, lead-free solder, or
nickel, or a multi-layer laminate of these metals at predetermined
portions (electrodes) on a surface of a semiconductor chip having
interconnects formed therein, and to electrically connect the
interconnects via the bumps with electrodes of a package or with
TAB electrodes. Methods of forming bumps include various methods,
such as electroplating, vapor deposition, printing, and ball
bumping. With a recent increase in the number of I/O in a
semiconductor chip and a trend toward finer pitches, electroplating
has more frequently been employed because it can cope with fine
processing and has relatively stable performance.
[0004] With an electroplating method, a metal film (plated film)
having a high purity can readily be obtained. Further, an
electroplating method has a relatively high deposition rate of a
metal film, and control of thickness of the metal film can be
performed relatively easily.
[0005] FIG. 37 shows an example of a conventional plating apparatus
which employs a so-called face-down method. The plating apparatus
has an upwardly opened plating tank 12 for holding a plating
solution 10 therein and a vertically movable substrate holder 14
for detachably holding a substrate W in a state such that a front
face (surface to be plated) of the substrate W faces downward
(face-down). An anode 16 is disposed horizontally at a bottom of
the plating tank 12. Overflow tanks 18 are provided around an upper
portion of the plating tank 12. Further, a plating solution supply
nozzle 20 is connected to the bottom of the plating tank 12.
[0006] In operation, a substrate W held horizontally by the
substrate holder 14 is located at a position such as to close an
opening at an upper end of the plating tank 12. In this state, the
plating solution 10 is supplied from the plating solution supply
nozzle 20 into the plating solution tank 12 and allowed to overflow
the upper portion of the plating tank 12, thereby bringing the
plating solution 10 into contact with a surface of the substrate W
held by the substrate holder 14. Simultaneously, the anode 16 is
connected via a conductor 22a to an anode of a plating power supply
24, and the substrate W is connected via a conductor 22b to a
cathode of the plating power supply 24. Thus, due to a potential
difference between the substrate W and the anode 16, metal ions in
the plating solution 10 receive electrons from the surface of the
substrate W, so that metal is deposited on the surface of the
substrate W so as to form a metal film.
[0007] According to the plating apparatus, uniformity of the
thickness of the metal film formed on the surface of the substrate
W can be adjusted to a certain extent by adjusting the size of the
anode 16, an interpolar distance and potential difference between
the anode 16 and the substrate W, a supply rate of the plating
solution 10 supplied from the plating solution supply nozzle 20,
and the like.
[0008] FIG. 38 shows an example of a conventional plating apparatus
which employs a so-called dipping method. The plating apparatus has
a plating tank 12a for holding a plating solution 12a therein and a
vertically movable substrate holder 14a for detachably holding a
substrate W in a state such that a front face (surface to be
plated) is exposed while a peripheral portion of the substrate W is
water-tightly sealed. An anode 16a is held by an anode holder 26
and disposed vertically within the plating tank 12. Further, a
regulation plate 28 made of a dielectric material having a central
hole 28a is disposed in the plating tank 12 so as to be positioned
between the anode 16a and the substrate W when the substrate W held
by the substrate holder 14a is disposed at a position facing the
anode 16a.
[0009] In operation, the anode 16a, the substrate W, and the
regulation plate 28 are immersed in the plating solution in the
plating tank 12a. Simultaneously, the anode 16a is connected via a
conductor 22a to an anode of a plating power supply 24, and the
substrate W is connected via a conductor 22b to a cathode of the
plating power supply 24. Accordingly, metal is deposited onto the
surface of the substrate W so as to form a metal film in the same
manner as described above.
[0010] According to the plating apparatus, distribution of
thickness of the metal film formed on the surface of the substrate
W can be adjusted to a certain extent by disposing the regulation
plate 28 having the central hole 28a between the anode 16a and the
substrate W disposed at a position facing the anode 16a, and
adjusting a potential distribution on the plating bath 12a with the
regulation plate 28.
[0011] FIG. 39 shows another example of a conventional plating
apparatus which employs a so-called dipping method. The plating
apparatus differs from the apparatus shown in FIG. 38 in that a
ring-shaped dummy cathode (dummy electrode) 30 is provided instead
of a regulation plate, that a substrate W is held by a substrate
holder 14a in a state such that the dummy cathode 30 is disposed
around the substrate W, and that the dummy cathode 30 is connected
to a cathode of a plating power supply 24 during plating.
[0012] According to the plating apparatus, uniformity of thickness
of a plated film formed on the surface of the substrate W can be
improved by adjusting an electric potential of the dummy cathode
30.
[0013] On the other hand, for example, when a metal film (plated
film) for interconnects or bumps is formed on a surface of a
semiconductor substrate (wafer), the metal film formed is required
to be uniform in surface profile and in film thickness over the
entire surface of the substrate. There are increasing demands for a
high degree of uniformity in recent high-density packaging
technologies such as SOC and WL-CSP. However, with the above
conventional plating apparatuses, it is quite difficult to form a
metal film that meets a high degree of uniformity requirement.
[0014] Specifically, when a substrate is plated by the plating
apparatus shown in FIG. 37, a metal film is formed under a strong
influence of a flow of the plating solution. If the plating
solution flows fast, as shown in FIG. 40A, the thickness of the
metal film P tends to be thicker in a central portion of the
substrate W, to which metal ions are sufficiently supplied, than in
a peripheral portion of the substrate W. If the flow of the plating
the solution is made considerably weak in order to prevent the
above phenomenon, as shown in FIG. 40B, the thickness of the metal
film P tends to be thicker in a peripheral portion of the substrate
W than in a central portion. When a substrate W is plated by the
plating apparatus shown in FIG. 38, a potential distribution can be
improved by the regulation plate having the central hole, so that
the uniformity of the film thickness distribution of a metal film
can be improved to a certain extent over the entire surface of the
substrate. However, as shown in FIG. 40C, the metal film P tends to
have an undulate thickness distribution, in which the film
thickness is thicker in a central portion and a peripheral portion
of the substrate W. Further, when a substrate is plated by the
plating apparatus shown in FIG. 39, it is difficult to adjust a
voltage applied to the dummy electrode (dummy cathode). In
addition, it becomes necessary to remove a metal film attached to a
surface of the dummy electrode, and the removal necessitates a
troublesome operation.
[0015] In the conventional plating apparatuses, there is a general
tendency that due to a surface potential distribution produced over
a surface of a substrate, the film thickness of a plated film is
larger in a peripheral portion of the substrate, which serves as an
electrically receiving portion, causing a U-shaped film thickness
distribution over the substrate surface (see FIG. 40B). This is one
of the main factors that impair the uniformity of film thickness.
In order to suppress this phenomenon, a regulation plate or a dummy
electrode is employed in a method of regulating supply of metal
ions to a surface of a substrate, i.e. regulating a flow of a
plating solution, and a method of controlling or regulating a
potential distribution on a surface of a substrate and an electric
field in a plating tank.
[0016] The regulating method of a flow of a plating solution and
the regulating method using a regulation plate are intended to
concentrate metal ions or an electric field to a central portion of
a substrate to raise a plated film at the central portion of the
substrate, thereby adjusting a film thickness distribution of the
plated film over the entire substrate surface so as to be a
W-shaped distribution and minimizing a film thickness variation
from an average film thickness (see FIG. 40C). Accordingly, the
uniformity of the film thickness is greatly influenced by
regulation of the flow of the plating solution and by selection and
fine control of the position of the regulation plate and the size
of the central hole. Thus, the uniformity of the film thickness is
greatly influenced by the degree of adjustment (tuning).
[0017] On the other hand, the method using a dummy electrode is
intended to broaden a range of a potential distribution from a
substrate surface to a region including the dummy electrode around
the substrate, thereby shifting the raised portion of the plated
film in the electrically receiving portion to the dummy electrode
and obtaining an extremely uniform film thickness on the substrate
surface. As an equivalent method to the method employing a dummy
electrode, there has also been known a method which uses a pattern
in a peripheral portion of a substrate as a "discarded chip" so as
to serve as a dummy electrode. In such methods that employ a dummy
electrode, the uniformity of the film thickness is influenced by
adjustment of a voltage. Further, it is necessary to periodically
remove a metal film (plated film) attached to the dummy electrode,
which necessitates a troublesome operation. When a pattern in a
peripheral portion of a substrate is used as a "discarded chip" so
as to serve as a dummy electrode, the number of effective chips per
substrate is inevitably reduced to thereby cause a lowered
productivity.
[0018] All of the above-described methods eventually adjust a film
thickness distribution to obtain a uniform film thickness
distribution. Thus, none of the above-described methods are
intended to positively control or regulate an electric field in a
plating tank, which is produced between an anode and a plating
workpiece as a cathode, so as to control and improve a potential
distribution on a surface of the plating workpiece, thereby
equalizing and improving the film thickness distribution of the
plated film which would otherwise become a U-shaped
distribution.
SUMMARY OF THE INVENTION
[0019] The present invention has been made in view of the above
drawback. It is, therefore, an object of the present invention to
provide a plating apparatus which can form a metal film (plated
film) having a uniform thickness over an entire plating workpiece
with a relatively simple arrangement and without needs for a
complicated operation and setting.
[0020] In order to achieve the above object, the present invention
provides a plating apparatus characterized by comprising a plating
tank for holding a plating solution; an anode disposed so as to be
immersed in the plating solution in the plating tank; a regulation
plate disposed between the anode and a plating workpiece disposed
so as to face the anode; and a plating power supply for supply a
current between the anode and the plating workpiece to carry out
plating, wherein the regulation plate is disposed so as to separate
the plating solution held in the plating tank into a plating
solution on the anode side and a plating solution on the plating
workpiece side, and a through-hole group having a large number of
through-holes is formed in the regulation plate.
[0021] According to the present invention, an electric field leaks
through a large number of through-holes formed in the regulation
plate disposed in the plating tank, and the leaked electric field
spreads uniformly. Accordingly, a potential distribution can be
made more uniform over an entire surface of the plating workpiece,
and a within wafer uniformity of a metal film formed on the surface
of the plating workpiece can be enhanced. Further, the plating
solution is prevented from passing through a large number of
through-holes formed in the regulation plate provided in the
plating tank. Accordingly, a non-uniform metal film thickness is
prevented from being formed on the surface of the plating workpiece
due to influence of a flow of the plating solution.
[0022] According to a preferred aspect of the present invention,
the through-hole group is formed by a plurality of slit-like
elongated holes extending linearly in one direction or extending in
an arc. The use of slit-like elongated holes as the through-holes
can promote leakage of electric field while preventing the plating
solution from passing through the through-holes. For example, the
widths of the elongated holes are set to be about 0.5 to 20 mm,
preferably about 1 to 15 mm. The lengths of the elongated holes are
determined depending upon the shape of the plating workpiece.
[0023] According to a preferred aspect of the present invention,
the through-hole group is formed by a plurality of cross holes
extending crosswise in vertical and horizontal directions.
[0024] According to a preferred aspect of the present invention,
the through-hole group is formed by a combination of a plurality of
fine holes, a plurality of holes having different diameters, and
slit-like elongated holes. The use of a combination of a plurality
of fine holes, a plurality of holes having different diameters, and
slit-like elongated holes as the through-hole group can increase
the productivity. For example, the diameters of the fine holes or
small holes (peripheral holes) are set to be about 1 to 20 mm,
preferably about 2 to 10 mm. For example, the diameters of large
holes (central holes) are set to be about 50 to 300 mm, preferably
about 30 to 100 mm.
[0025] It is desirable that the through-hole group be formed in the
regulation plate substantially over an entire area facing the
plating workpiece, and formed in an area substantially similar to a
shape of the plating workpiece. With such a through-hole group, it
is possible to form a metal film having a good film thickness
uniformity in all directions on the plating workpiece.
[0026] Preferably, the plating apparatus comprises an agitating
mechanism provided between the plating workpiece and the regulation
plate for stirring the plating solution held in the plating tank.
By agitating the plating solution between the plating workpiece and
the regulation plate by the agitating mechanism during plating,
sufficient ions can be supplied more uniformly to the plating
workpiece. Therefore, a metal film having a more uniform thickness
can be formed more rapidly.
[0027] Preferably, the agitating mechanism should comprise a
paddle-type agitating mechanism having a paddle which reciprocates
parallel to the plating workpiece. By reciprocating a paddle
parallel to the plating workpiece during plating to agitate the
plating solution by the paddle, the directionality of the flow of
the plating solution can be eliminated, and simultaneously
sufficient ions can be supplied more uniformly to the surface of
the plating workpiece.
[0028] According to a preferred aspect of the present invention,
the anode and the regulation plate are provided in a vertical
direction. This arrangement provides a plating apparatus with a
small installation space and having excellent maintainability.
[0029] The present invention also provides another plating
apparatus characterized by comprising a plating tank for holding a
plating solution; an anode disposed so as to be immersed in the
plating solution in the plating tank; a regulation plate disposed
between the anode and a plating workpiece disposed so as to face
the anode; and a plating power supply for supply a current between
the anode and the plating workpiece to carry out plating, wherein
the regulation plate is disposed so as to separate the plating
solution held in the plating tank into a plating solution on the
anode side and a plating solution on the plating workpiece side,
and a plating solution passage is formed in the regulation plate
for allowing an electric field to uniformly pass therethrough and
allowing the plating solution to pass therethrough.
[0030] By thus allowing the electric field produced between the
anode and the plating workpiece in the plating tank to pass
uniformly through the plating solution passage without leaking out
of the plating solution passage, distortion or deviation of the
electric field can be adjusted and corrected so as to equalize a
potential distribution over an entire surface of the plating
workpiece, thereby enhancing a within wafer uniformity of a metal
film formed on the plating workpiece.
[0031] The length of the plating solution passage is properly
determined depending upon the shape of the plating tank, the
distance between the anode and the plating workpiece, and the like.
However, the length is generally 10 to 90 mm, preferably 20 to 75
mm, more preferably 30 to 60 mm.
[0032] Preferably, the plating solution passage is defined by an
inner circumferential surface of a cylindrical member or a
rectangular block. This arrangement can simplify the structure.
[0033] It is desirable that a large number of through-holes having
a size such as to prevent leakage of an electric field be formed in
a circumferential wall of the cylindrical member. With this
arrangement, the plating solution is allowed to pass through the
through-holes formed in the circumferential wall of the cylindrical
member while preventing leakage of the electric field. Accordingly,
the concentration of the plating solution is prevented from being
different between the inside and outside of the cylindrical member.
With respect to the shape of the through-holes, for example, fine
holes, slit-like elongated holes, cross holes extending vertically
and horizontally, and a combination thereof may be exemplified.
[0034] According to a preferred aspect of the present invention,
the plating apparatus comprises an agitating mechanism provided in
at least one of a space between the plating workpiece and the
regulation plate and a space between the anode and the regulation
plate for agitating the plating solution held in the plating tank.
By agitating the plating solution during plating, the concentration
of the plating solution containing metal ions and various additives
can be made uniform in the plating tank, and the plating solution
having a uniform concentration can be supplied to the plating
workpiece. Accordingly, a metal film having a more uniform
thickness can be formed more rapidly.
[0035] The agitating mechanism is preferably a paddle-type
agitating mechanism having a paddle which reciprocates parallel to
the plating workpiece.
[0036] The agitating mechanism may comprise a plating solution
injection type agitating mechanism having a plurality of plating
solution injection nozzles for ejecting the plating solution toward
the plating workpiece. By injecting the plating solution from the
plurality of plating solution injection nozzles toward the plating
workpiece, the plating solution in the plating tank can be agitated
so as to uniformize the plating solution concentration and,
simultaneously, to sufficiently supply components of the plating
solution to the plating workpiece. Thus, a metal film having a more
uniform thickness can be formed more rapidly.
[0037] The plating solution passage may be formed in the regulation
plate integrally with the regulation plate. A thick regulation
plate may be used, and a through-hole may be formed in the
regulation plate so as to serve as a plating solution passage.
[0038] The present invention provides yet another plating apparatus
comprising a plating tank for holding a plating solution; an anode
disposed so as to be immersed in the plating solution in the
plating tank; a regulation plate disposed between the anode and a
plating workpiece disposed so as to face the anode for separating
the plating solution held in the plating tank into a plating
solution on the anode side and a plating solution on the plating
workpiece side, the regulation plate having a plating solution
passage for allowing an electric field to uniformly pass
therethrough and allowing the plating solution to pass
therethrough; a plating power supply for supply a current between
the anode and the plating workpiece to carry out plating; and an
electric field adjustment ring disposed at an end of the plating
solution passage on the plating workpiece side for adjusting an
electric field at a peripheral portion of the plating
workpiece.
[0039] By adjusting an electric field at a peripheral portion of
the plating workpiece by the electric field adjustment ring, an
electric field produced between the anode and the plating workpiece
can be uniformized over an entire surface of the plating workpiece,
including an edge portion of the plating workpiece, which serves as
an electrically receiving portion. Therefore, a within wafer
uniformity of a metal film formed on the plating workpiece can be
further enhanced.
[0040] The shape of the electric field adjustment ring may be
properly determined depending upon the shape of the plating tank,
the shape of the plating workpiece, the distance between the anode
and the plating workpiece, and the like. The width of the ring is
generally set to be in a range of 1 to 20 mm, preferably 3 to 17
mm, more preferably 5 to 15 mm.
[0041] A gap between the electric field adjustment ring and the
plating workpiece is generally set to be in a range of 0.5 to 30
mm, preferably 1 to 15 mm, more preferably 1.5 to 6 mm.
[0042] According to a preferred aspect of the present invention,
the plating solution passage is defined by an inner circumferential
surface of a cylindrical member, and the electric field adjustment
ring is connected to an end of the cylindrical member on the
plating workpiece side.
[0043] Alternatively, the plating solution passage may be defined
by an inner circumferential surface of a cylindrical member, and
the electric field adjustment ring may be disposed at an end of the
cylindrical member on the plating workpiece side so as to be
separated from the cylindrical member. With such a separated
plating solution passage, the cylindrical member and the electric
field adjustment ring can be separated so as to offer a broader
choice.
[0044] Alternatively, the plating solution passage may be defined
by an inner circumferential surface of a cylindrical member, and
the electric field adjustment ring may be formed on an end surface
of the plating workpiece side. With this arrangement, the number of
parts can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 is an overall layout of a plating facility having a
plating apparatus according to an embodiment of the present
invention;
[0046] FIG. 2 is a schematic view of a transfer robot provided in a
plating space of a plating processing apparatus shown in FIG.
1;
[0047] FIG. 3 is a schematic cross-sectional view of a plating
apparatus provided in the plating processing apparatus shown in
FIG. 1;
[0048] FIG. 4 is a schematic perspective view of a main portion of
the plating apparatus shown in FIG. 3;
[0049] FIG. 5 is a plan view of a regulation plate provided in the
plating apparatus shown in FIG. 3;
[0050] FIG. 6 is a schematic diagram illustrating a state of a
metal film (plated film) formed by the plating apparatus shown in
FIG. 3;
[0051] FIGS. 7A through 7E are cross-sectional diagrams
sequentially illustrating a process of forming a bump (protruding
electrode) on a substrate;
[0052] FIG. 8 is a plan view showing another example of a
regulation plate;
[0053] FIG. 9 is a plan view showing still another example of a
regulation plate;
[0054] FIG. 10 is a plan view showing yet another example of a
regulation plate;
[0055] FIG. 11 is a plan view showing yet another example of a
regulation plate;
[0056] FIG. 12 is a plan view showing yet another example of a
regulation plate;
[0057] FIG. 13 is a plan view showing yet another example of a
regulation plate;
[0058] FIG. 14 is a plan view showing yet another example of a
regulation plate;
[0059] FIG. 15 is a plan view showing yet another example of a
regulation plate;
[0060] FIG. 16 is a plan view showing yet another example of a
regulation plate;
[0061] FIG. 17 is a plan view showing yet another example of a
regulation plate;
[0062] FIG. 18 is a plan view showing yet another example of a
regulation plate;
[0063] FIG. 19 is a plan view showing yet another example of a
regulation plate;
[0064] FIG. 20 is a schematic cross-sectional view showing a
plating apparatus according to another embodiment of the present
invention;
[0065] FIG. 21A is a perspective view showing a regulation plate
and a cylindrical member provided in the plating apparatus shown in
FIG. 20;
[0066] FIG. 21B is a front view of FIG. 21A;
[0067] FIG. 22 is a schematic diagram illustrating a state of a
metal film (plated film) formed by the plating apparatus shown in
FIG. 20;
[0068] FIG. 23 is a schematic cross-sectional view showing a
plating apparatus according to still another embodiment of the
present invention;
[0069] FIG. 24A is a perspective view showing another example of a
regulation plate and a cylindrical member;
[0070] FIG. 24B is a front view of FIG. 24A;
[0071] FIG. 25A is a perspective view showing still another example
of a regulation plate and a cylindrical member;
[0072] FIG. 25B is a front view of FIG. 25A;
[0073] FIG. 26A is a perspective view showing yet another example
of a regulation plate and a cylindrical member;
[0074] FIG. 26B is a front view of FIG. 26A;
[0075] FIG. 27A is a perspective view showing yet another example
of a regulation plate and a cylindrical member;
[0076] FIG. 27B is a front view of FIG. 27A;
[0077] FIG. 28 is a schematic cross-sectional view showing a
plating apparatus according to yet another embodiment of the
present invention;
[0078] FIG. 29A is a perspective view showing a regulation plate, a
cylindrical member, and an electric field adjustment ring provided
in the plating apparatus shown in FIG. 28;
[0079] FIG. 29B is a front view of FIG. 29A;
[0080] FIG. 30 is a schematic diagram illustrating a metal film
(plated film) formed by the plating apparatus shown in FIG. 28;
[0081] FIG. 31 is a schematic cross-sectional view showing a
plating apparatus according to yet another embodiment of the
present invention;
[0082] FIG. 32A is a perspective view showing another example of a
regulation plate, a cylindrical member, and an electric field
adjustment ring;
[0083] FIG. 32B is a front view of FIG. 32A;
[0084] FIG. 33A is a perspective view showing still another example
of a regulation plate, a cylindrical member, and an electric field
adjustment ring;
[0085] FIG. 33B is a front view of FIG. 33A;
[0086] FIG. 34A is a perspective view showing yet another example
of a regulation plate, a cylindrical member, and an electric field
adjustment ring;
[0087] FIG. 34B is a front view of FIG. 34A;
[0088] FIG. 35A is a perspective view showing yet another example
of a regulation plate, a cylindrical member, and an electric field
adjustment ring;
[0089] FIG. 35B is a front view of FIG. 35A;
[0090] FIG. 36 is a schematic cross-sectional view showing a
plating apparatus according to yet another embodiment of the
present invention;
[0091] FIG. 37 is a schematic cross-sectional view showing an
example of a conventional plating apparatus;
[0092] FIG. 38 is a schematic perspective view showing another
example of a conventional plating apparatus;
[0093] FIG. 39 is a schematic perspective view showing still
another example of a conventional plating apparatus; and
[0094] FIGS. 40A through 40C are schematic diagrams illustrating
various states of metal films (plated films) formed by conventional
plating apparatuses.
BEST MODE FOR CARRYING OUT THE INVENTION
[0095] Embodiments of the present invention will be described below
with reference to the drawings. The following embodiments show
examples in which a substrate such as a semiconductor wafer is used
as a plating workpiece.
[0096] FIG. 1 shows an overall layout of a plating facility having
a plating apparatus according to an embodiment of the present
invention. The plating facility is designed so as to automatically
perform all the plating processes including pretreatment of a
substrate, plating, and post treatment of the plating, in a
successive manner. The interior of an apparatus frame 110 having an
armored panel attached thereto is divided by a partition plate 112
into a plating space 116 for performing a plating process of a
substrate and treatments of the substrate to which a plating
solution is attached, and a clean space 114 for performing other
processes, i.e. processes not directly involving a plating
solution. Two substrate holders 160 (see FIG. 2) are arranged in
parallel, and substrate attachment/detachment stages 162 to attach
a substrate to and detach a substrate from each substrate holder
160 are provided as a substrate delivery section on a partition
portion partitioned by the partition plate 112, which divides the
plating space 116 from the clean space 114. Loading/unloading ports
120, on which substrate cassettes storing substrates are mounted,
are connected to the clean space 114. Further, the apparatus frame
110 has a console panel 121 provided thereon.
[0097] In the clean space 114, there are disposed at four corners
an aligner 122 for aligning an orientation flat or a notch of a
substrate with a predetermined direction, two cleaning/drying
devices 124 for cleaning a plated substrate and rotating the
substrate at a high speed to spin-dry the substrate, and a
pretreatment device 126 for carrying out a pretreatment of a
substrate, e.g., according to the present embodiment, a rinsing
pretreatment including injecting pure water toward a front face
(surface to be plated) of a substrate to thereby clean the
substrate surface with pure water and, at the same time, wet the
substrate surface with pure water so as to enhance a hydrophilicity
of the substrate surface. Further, a first transfer robot 128 is
disposed substantially at the center of these processing devices,
i.e. the aligner 122, the cleaning/drying devices 124, and the
pretreatment device 126, to thereby transfer and deliver a
substrate between the processing devices 122, 124, and 126, the
substrate attachment/detachment stages 162, and the substrate
cassettes mounted on the loading/unloading ports 120.
[0098] The aligner 122, the cleaning/drying devices 124, and the
pretreatment device 126 disposed in the clean space 114 are
designed so as to hold and process a substrate in a horizontal
state in which a front face of the substrate faces upward. The
transfer robot 128 is designed so as to transfer and deliver a
substrate in a horizontal state in which a front face of the
substrate faces upward.
[0099] In the plating space 116, in order from the partition plate
112, there are disposed a stocker 164 for storing or temporarily
storing the substrate holders 160, an activation treatment device
166 for etching, for example, an oxide film, having a large
electric resistance, on a seed layer formed on a surface of a
substrate with a chemical liquid such as sulfuric acid or
hydrochloric acid to remove the oxide film, a first rinsing device
168a for rinsing the surface of the substrate with pure water, a
plating apparatus 170 for carrying out plating, a second rinsing
device 168b, and a blowing device 172 for dewatering the plated
substrate. Two second transfer robots 174a and 174b are disposed
beside these devices so as to be movable along a rail 176. One of
the second transfer robots 174a transfers the substrate holders 160
between the substrate attachment/detachment stages 162 and the
stocker 164. The other of the second transfer robots 174b transfers
the substrate holders 160 between the stocker 164, the activation
treatment device 166, the first rinsing device 168a, the plating
apparatus 170, the second rinsing device 168b, and the blowing
device 172.
[0100] As shown in FIG. 2, each of the second transfer robots 174a
and 174b has a body 178 extending in a vertical direction and an
arm 180 which is vertically movable along the body 178 and
rotatable about its axis. The arm 180 has two substrate holder
retaining portions 182 provided in parallel for detachably
retaining the substrate holders 160. The substrate holder 160 is
designed so as to hold a substrate W in a state in which a front
face of the substrate is exposed while a peripheral portion of the
substrate is sealed, and to be capable of attaching the substrate W
to the substrate holder 160 and detaching the substrate W from the
substrate holder 160.
[0101] The stocker 164, the activation treatment device 166, the
rinsing devices 168a, 168b, and the plating apparatus 170 are
designed so as to engage with outwardly projecting portions 160a
provided at both ends of each substrate holder 160 to thus support
the substrate holders 160 in a state such that the substrate
holders 160 are suspended in a vertical direction. The activation
treatment device 166 has two activation treatment tanks 183 for
holding a chemical liquid therein. As shown in FIG. 2, the arm 180
of the second transfer robot 174b holding the substrate holders
160, which are loaded with the substrates W, in a vertical state is
lowered so as to engage the substrate holders 160 with upper ends
of the activation treatment tanks 183 to support the substrate
holders 160 in a suspended manner as needed. Thus, the activation
treatment device 166 is designed so that the substrate holders 160
are immersed together with the substrates W in the chemical liquid
in the activation treatment tanks 183 to carry out an activation
treatment.
[0102] Similarly, the rinsing devices 168a and 168b have two
rinsing tanks 184a and two rinsing tanks 184b which hold pure water
therein, respectively, and the plating apparatus 170 has a
plurality of plating tanks 186 which hold a plating solution
therein. The rinsing devices 168a, 168b and the plating apparatus
170 are designed so that the substrate holders 160 are immersed
together with the substrates W in the pure water in the rinsing
tanks 184a, 184b or the plating solution in the plating tanks 186
to carry out rinsing treatment or plating in the same manner as
described above. The arm 180 of the second transfer robot 174b
holding the substrate holders 160 with substrates W in a vertical
state is lowered, and air or inert gas is injected toward the
substrates W mounted on the substrate holders 160 to blow away a
liquid attached to the substrate holders 160 and the substrates W
and to dewater the substrates W. Thus, the blowing device 172 is
designed so as to carry out blowing treatment.
[0103] As show in FIGS. 3 and 4, each plating tank 186 in the
plating apparatus 170 is designed so as to hold a plating solution
10 therein. Thus, the substrates W, which are held in a state such
that the front faces (surfaces to be plated) are exposed while
peripheral portions of the substrate holders 160 are water-tightly
sealed, are immersed in the plating solution 10.
[0104] Overflow tanks 46 are provided at both sides of the plating
tank 186 for receiving a plating solution 10 overflowing upper ends
of overflow weirs 44 of the plating tank 186. The overflow tanks 46
and the plating tank 186 are connected through a circulation pipe
48. The circulation pipe 48 has a circulating pump 50, a
thermostatic unit 52, and a filter 54 provided in the circulation
pipe 48. A plating solution 10 supplied into the plating tank 186
by operation of the circulating pump 50 fills the plating tank 186,
then overflows the overflow weirs 44, flows into the overflow tanks
46, and returns to the circulating pump 50. Thus, the plating
solution 10 is circulated.
[0105] An anode 56 having a circular shape corresponding to the
shape of the substrate W is held by an anode holder 58 and provided
vertically in the plating tank 186. Thus, when the plating solution
10 is filled in the plating tank 186, the anode 56 is immersed in
the plating solution 10. Further, a regulation plate 60 is provided
between the anode 56 and the substrate holder 160 to partition the
interior of the plating tank 186 into an anode side chamber 40a and
a substrate side chamber 40b and to separate the plating solution
10 held in the plating tank 186 into an anode side plating solution
and a substrate side plating solution.
[0106] A paddle-type agitating mechanism 64 having a plurality of
paddles 62 extending vertically downward is disposed between the
substrate holder 160 and the regulation plate 60. The paddles 62
are reciprocated within the plating solution in the substrate side
chamber 40b in parallel to the substrate W held by the substrate
holder 160, thereby stirring the plating solution in the substrate
side chamber 40b.
[0107] The regulation plate 60 has a thickness of, for example,
about 0.5 to 10 mm and is made of a dielectric material including
PVC, PP, PEEK, PES, HT-PVC, PFA, PTFE, and other resin materials. A
through-hole group 68 including a large number of through-holes 66
is provided in a predetermined area of the regulation plate 60,
which is substantially the entire area facing the surface of the
substrate W when the substrate W is held by the substrate holder
160 and located at a predetermined plating position in the plating
tank 186, and which is a circular area similar to the shape of the
substrate W.
[0108] According to the present embodiment, as particularly shown
in FIG. 5, the through-holes 66 are formed by slit-like elongated
holes extending linearly in a horizontal direction. The
through-holes (elongated holes) 66 are lineally arranged in
parallel within a circular area corresponding to the shape of the
substrate W so as to form the through-hole group 68. The
through-holes (elongated holes) 66 generally have a width of about
0.5 to 20 mm, preferably about 1 to 15 mm. The length of the
through-hole 66 is determined depending upon the size (diameter) of
the substrate W.
[0109] Thus, the through-hole group 68 including a large number of
through-holes 66 is provided in the regulation plate 60 so that an
electric field leaks through the respective through-holes 66 at the
time of plating, and so that the leaked electric field spreads
uniformly. Accordingly, a potential distribution can be made more
uniform over the entire surface (surface to be plated) of the
substrate W, and a within wafer uniformity of a metal film formed
on the surface of the substrate W can be enhanced. Further, the
plating solution 10 is prevented from passing through a large
number of through-holes 66 formed in the regulation plate 60
provided in the plating tank 186. Accordingly, a non-uniform metal
film thickness is prevented from being formed on the surface of the
substrate W due to influence of a flow of the plating solution 10
(return flow of the plating solution).
[0110] Particularly, the use of slit-like elongated holes as the
through-holes 66 can prevent the plating solution 10 from passing
through the through-holes (elongated holes) 66 and simultaneously
promote leakage of the electric field. Further, by forming the
through-hole group 68, including a large number of through-holes 66
(i.e., minimize the amount of plating solution passing through),
substantially in the entire area facing the surface of the
substrate W which is a circular area similar to the shape of the
substrate W, a metal film having a good film thickness uniformity
can be formed in all directions on the surface of the substrate
W.
[0111] With the plating apparatus 170, a plating solution 10 is
first filled in the plating tank 186 and circulated as described
above. In this state, the substrate holder 160 holding the
substrate W is lowered to locate the substrate W at a predetermined
position within the plating tank 186 at which the substrate W is
immersed in the plating solution 10. The anode 56 is connected via
a conductor 22a to an anode of a plating power supply 24, and the
substrate W is connected via a conductor 22b to a cathode of the
plating power supply 24. At the same time, the paddle-type
agitating mechanism 64 is operated so as to reciprocate the paddles
62 along the surface of the substrate W to thereby agitate the
plating solution 10 in the substrate side chamber 40b. As a result,
a metal is deposited on the surface of the substrate W so as to
form a metal film on the surface of the substrate W.
[0112] At that time, as described above, an electric field leaks
through a large number of through-holes 66 formed in the regulation
plate 60, and the leaked electric field spreads uniformly.
Accordingly, a potential distribution can be made more uniform over
the entire front face (surface to be plated) of the substrate W,
and a metal film P having an enhanced within wafer uniformity can
be formed on the surface of the substrate W as shown in FIG. 6.
Further, by agitating the plating solution 10 between the substrate
W and the regulation plate 60 with the paddles 62 during plating,
the directionality of the flow of the plating solution can be
eliminated, and simultaneously sufficient ions can be supplied more
uniformly to the surface of the substrate W. Therefore, a metal
film having a more uniform thickness can be formed more
rapidly.
[0113] After completion of the plating, the plating power supply 24
is disconnected from the substrate W and the anode 56, and the
substrate holder 160 is pulled up together with the substrate W.
After necessary treatments such as water-cleaning and rinsing of
the substrate W, the plated substrate W is transferred to a
subsequent process.
[0114] A series of bump plating processes in the plating facility
thus constructed will be described below with reference to FIGS. 7A
through 7E. First, as shown in FIG. 7A, a seed layer 500 is
deposited as a feeding layer on a surface of a substrate W, and a
resist 502 having a height H of, for example, about 20 to 120 .mu.m
is applied onto the entire surface of the seed layer 500.
Thereafter, an opening 502a having a diameter D.sub.1 of, for
example, about 20 to 200 .mu.m is formed at a predetermined
position of the resist 502. Substrates W thus prepared are housed
in a substrate cassette in a state such that front faces (surfaces
to be plated) of the substrates face upward. The substrate cassette
is mounted on the loading/unloading port 120.
[0115] One of the substrates W is taken out of the substrate
cassette mounted on the loading/unloading port 120 by the first
transfer robot 128 and placed on the aligner 122 to align an
orientation flat or a notch of the substrate with a predetermined
direction. The substrate W thus aligned is transferred to the
pretreatment device 126 by the first transfer robot 128. In the
pretreatment device 126, a pretreatment (rinsing pretreatment)
using pure water as a pretreatment liquid is carried out. On the
other hand, two substrate holders 160 which have been stored in a
vertical state in the stocker 164 are taken out by the second
transfer robot 174a, rotated through 90.degree. so that the
substrate holders 160 are brought into a horizontal state, and then
placed in parallel on the substrate attachment/detachment stages
162.
[0116] Then, the substrates W which have been subjected to the
aforementioned pretreatment (rinsing pretreatment) are loaded into
the substrate holders 160 placed on the substrate
attachment/detachment stages 162 in a state such that peripheral
portions of the substrates are sealed. The two substrate holders
160 which have been loaded with the substrates W are simultaneously
retained, lifted, and then transferred to the stocker 164 by the
second transfer robot 174a. The substrate holders 160 are rotated
through 90.degree. into a vertical state and lowered so that the
two substrate holders 160 are held (temporarily stored) in the
stocker 164 in a suspended manner. The above operation is carried
out repeatedly in a sequential manner, so that substrates are
sequentially loaded into the substrate holders 160, which are
stored in the stocker 164, and are sequentially held (temporarily
stored) in the stocker 164 at predetermined positions in a
suspended manner.
[0117] On the other hand, the two substrate holders 160 which have
been loaded with the substrates and temporarily stored in the
stocker 164 are simultaneously retained, lifted, and then
transferred to the activation treatment device 166 by the second
transfer robot 174b. Each substrate is immersed in a chemical
liquid such as sulfuric acid or hydrochloric acid held in the
activation treatment tank 183 to thereby etch an oxide film, having
a large electric resistance, formed on the surface of the seed
layer so as to expose a clean metal surface. The substrate holders
160 which have been loaded with the substrates are transferred to
the first rinsing device 168a in the same manner as described above
to rinse the surfaces of the substrates with pure water held in the
rinsing tanks 184a.
[0118] The substrate holders 160 which have been loaded with the
rinsed substrates are transferred to the plating apparatus 170 in
the same manner as described above. Each substrate W is supported
in a suspended manner by the plating tank 186 in a state such that
the substrate W is immersed in the plating solution 10 in the
plating tank 186 to thus carry out plating on the surface of the
substrate W. After a predetermined period of time has elapsed, the
substrate holders 160 which have been loaded with the substrates
are retained again and pulled up from the plating tank 186 by the
second transfer robot 174b. Thus, the plating process is
completed.
[0119] Thereafter, the substrate holders 160 are transferred to the
second rinsing device 168b in the same manner as described above.
The substrate holders 160 are immersed in pure water in the rinsing
tanks 184b to clean the surfaces of the substrates with pure water.
Then, the substrate holders 160 which have been loaded with the
substrates are transferred to the blowing device 172 in the same
manner as described above. In the blowing device 172, inert gas or
air is injected toward the substrates to blow away a plating
solution and water droplets attached to the substrate holders 160.
Thereafter, the substrate holders 160 which have been loaded with
the substrates are returned to predetermined positions in the
stocker 164 and held in a suspended state in the same manner as
described above.
[0120] The second transfer robot 174b sequentially performs the
above operation repeatedly so that the substrate holders 160 which
have been loaded with the plated substrates are sequentially
returned to predetermined positions in the stocker 164 and held in
a suspended manner.
[0121] On the other hand, the two substrate holders 160 which have
been loaded with the plated substrates are simultaneously retained
and placed on the substrate attachment/detachment stages 162 by the
second transfer robot 174a in the same manner as described
above.
[0122] The first transfer robot 128 disposed in the clean space 114
takes the substrate out of the substrate holders 160 placed on the
substrate attachment/detachment stages 162 and transfers the
substrate to either one of the cleaning/drying devices 124. In the
cleaning/drying device 124, the substrate held in a horizontal
state such that the front face of the substrate faces upward is
cleaned with pure water or the like and rotated at a high speed to
spin-dry the substrate. Thereafter, the substrate is then returned
to the substrate cassette mounted on the loading/unloading port 120
by the first transfer robot 128. Thus, a series of plating
processes is completed. As a result, as shown in FIG. 7B, a
substrate W having a plated film 504 grown in the opening 502a
formed in the resist 502 can be obtained.
[0123] The spin-dried substrate W as described above is immersed in
a solvent such as acetone at a temperature of, for example, 50 to
60.degree. C. to remove the resist 502 from the substrate W as
shown in FIG. 7C. Further, as shown in FIG. 7D, an unnecessary seed
layer 502, which is exposed after plating, is removed. Next, the
plated film 504 formed on the substrate W is reflowed to form a
bump 506 having a round shape due to surface tension. The substrate
W is then annealed at a temperature of, for example, 100.degree. C.
or more to remove residual stress in the bump 506.
[0124] According to this embodiment, delivery of substrates in the
plating space 116 is performed by the second transfer robots 174a
and 174b disposed in the plating space 116, whereas delivery of
substrates in the clean space 114 is performed by the first
transfer robot 128 disposed in the clean space 114. Accordingly, it
is possible to improve the cleanliness around a substrate in the
plating processing apparatus which performs all the plating
processes including pretreatment of a substrate, plating, and
post-treatment of the plating, in a successive manner, and to
increase a throughput of the plating processing apparatus. Further,
it is possible to reduce loads on facilities associated with the
plating processing apparatus and to achieve downsizing of the
plating processing apparatus.
[0125] According to the present embodiment, a plating tank 186
having a small footprint is used in the plating apparatus 170 for
carrying out plating. Accordingly, it is possible to achieve
further downsizing of the plating apparatus having a large number
of plating tanks 186 and reduce loads on associated facilities in a
plant. In FIG. 1, one of the two cleaning/drying devices 124 may be
replaced with a pretreatment device.
[0126] FIGS. 8 through 19 show various examples of a through-hole
group including a large number of through-holes in a regulation
plate 60. Specifically, FIG. 8 shows an example in which
through-holes 66a are formed by slit-like elongated holes extending
linearly in a vertical direction, and the through-holes (elongated
holes) 66a are arranged linearly in parallel in a circular area
corresponding to the shape of a substrate W so as to form a
through-hole group 68a. FIG. 9 shows an example in which
through-holes (elongated holes) 66b are arranged linearly in
parallel in a rectangular area corresponding to the shape of a
substrate W so as to form a through-hole group 68b, which is
suitable for a rectangular substrate W.
[0127] FIG. 10 shows an example in which a through-hole group 68c
is formed by a plurality of through-holes (elongated holes) 66c
which are slit-like elongated holes extending linearly
substantially across the entire width of an area of a regulation
plate 60 facing a surface of a substrate W. In this case, when a
rectangular substrate W is used, as shown in FIG. 11, through-holes
(elongated holes) 66d may be arranged in parallel in a rectangular
area corresponding to the shape of the substrate W so as to form a
through-hole group 68d. Further, the through-holes 66d may be
arranged so as to extend linearly in a vertical direction, which is
not shown.
[0128] FIG. 12 shows an example in which through-holes (cross
holes) 66e which are cross holes extending crosswise in vertical
and horizontal directions are arranged uniformly in a circular area
so as to form a through-hole group 68e. In this case, when a
rectangular substrate W is used, as shown in FIG. 13, through-holes
(cross holes) 66f may be arranged uniformly in a rectangular area
corresponding to the shape of the substrate W so as to form a
through-hole group 68f.
[0129] FIG. 14 shows an example in which a plurality of
through-holes (fine holes) 66g which are fine holes is distributed
uniformly in a circular area so as to form a through-hole group
68g. In this illustrated example, the diameter of each through-hole
(fine hole) 66g is set to be 2 mm, and 633 holes are provided in
total. Although the diameters of the through-holes 66g as well as
small holes (peripheral holes) 66h.sub.2 through 66h.sub.5
described below may be set arbitrarily within a range of, for
example, 1 to 20 mm, they should preferably be in a range of about
2 to 10 mm. When the through-hole group 68g is formed by the
through-holes (fine holes) 66g, productivity of the regulation
plate 60 can be increased.
[0130] FIG. 15 shows an example in which a through-hole group 68h
is formed by a plurality of through-holes 66h having different
diameters, i.e. a large hole (central hole) 66h.sub.1 having a
large diameter and located at a central portion, and small holes
(peripheral holes) 66h.sub.2 through 66h.sub.5 arranged outside of
the large hole 66h.sub.1 along a circumferential direction in a
plurality of arrays (four arrays in FIG. 15) having diameters
gradually reduced in a radial direction. The diameter of the large
hole (central hole) 66h.sub.1 is set to be 84 mm in this example.
Although the diameter of the large hole may be set arbitrarily
within a range of, for example, 50 to 300 mm, it should preferably
be in a range of about 30 to 100 mm. The diameters of the small
holes (peripheral holes) 66h.sub.2 through 66h.sub.5 are set to be
10 mm, 8 mm, 7 mm, and 6 mm, respectively.
[0131] FIG. 16 shows an example in which a through-hole group 68J
is formed by a plurality of through-holes 66J including a central
hole 66i.sub.1 located at a central portion, and elongated holes
66i.sub.2 through 66i.sub.6 arranged outside of the central hole
66i.sub.1 along a circumferential direction in a plurality of
arrays (five arrays in FIG. 16). In this example, the diameter of
the central hole 66i.sub.1 is set to be 34 mm, and the widths of
the elongated holes 66i.sub.2 through 66i.sub.6 are set to be 27
mm, 18.5 mm, 7 mm, 7 mm, and 7 mm, respectively.
[0132] FIG. 17 shows an example in which a through-hole group 68j
is formed by a plurality of through-holes 66j including a large
hole (central hole) 66j.sub.1 having a large diameter and located
at a central portion, elongated holes 66j.sub.2 arranged outside of
the central hole 66j.sub.1 along a circumferential direction, and
small holes (peripheral holes) 66j.sub.3 through 66j.sub.6 arranged
outside of the elongated holes 66j.sub.2 in a plurality of arrays
(four arrays in FIG. 17) having diameters gradually reduced in a
radial direction. In this example, the diameter of the large hole
(central hole) 66j.sub.1 is set to be 67 mm, the width of the
elongated hole 66j.sub.2 is set to be 17 mm, and the diameters of
the small holes (peripheral holes) 66j.sub.3 through 66j.sub.6 are
set to be 9 mm, 8 mm, 7 mm, and 6 mm, respectively.
[0133] FIG. 18 shows an example in which a through-hole group 68k
is formed by a plurality of through-holes 66k including a large
hole (central hole) 66k.sub.1 having a large diameter and located
at a central portion, elongated holes 66k.sub.2, 66k.sub.3 arranged
outside of the central hole 66k.sub.1, along a circumferential
direction in a plurality of arrays (two arrays in FIG. 18), and
small holes (peripheral holes) 66k.sub.4, 66k.sub.5 arranged
outside of the elongated holes 66k.sub.3 in a plurality of arrays
(two arrays in FIG. 18) having diameters gradually reduced in a
radial direction. In this example, the diameter of the large hole
(central hole) 66k.sub.1 is set to be 80 mm, the widths of the
elongated holes 66k.sub.2, 66k.sub.3 are set to be 7 mm, and the
diameters of the small holes (peripheral holes) 66k.sub.4,
66k.sub.5 are set to be 6 mm and 4 mm, respectively.
[0134] FIG. 19 shows an example in which a through-hole group 68l
is formed by a plurality of through-holes 661 including a large
hole (central hole) 66l.sub.1 having a large diameter and located
at a central portion, and a plurality of slit-like elongated holes
66l.sub.2 arranged outside of the central hole 66l.sub.1 at a
predetermined pitch along a circumferential direction and extending
linearly in a radial direction. The widths of the elongated holes
66l.sub.2 are generally in a range of about 0.5 to 20 mm,
preferably about 1 to 15 mm. The lengths of the elongated holes
66l.sub.2 are set arbitrarily according to the shape of a plating
workpiece.
[0135] Thus, a through-hole group is formed by a combination of a
plurality of through-holes having desired shapes, such as a
plurality of fine holes, a plurality of holes having different
diameters, and slit-like elongated holes. Accordingly, a
through-hole group can meet various requirements regarding plating
sites, plating conditions, and the like.
[0136] In the examples shown in FIGS. 14 through 19, through-holes
are arranged in a circular area so as to form a through-hole group.
However, as described above, when a rectangular substrate is used,
through-holes may be arranged, as a matter of course, in a
rectangular area corresponding to the shape of the substrate so as
to form a through-hole group.
[0137] As described above, according to the present invention, an
electric field leaks through a large number of through-holes formed
in a regulation plate provided in the plating tank, and the leaked
electric field spreads uniformly. Accordingly, a potential
distribution can be made more uniform over the entire surface of a
plating workpiece, and a within wafer uniformity of a metal film
formed on the surface of the plating workpiece can be enhanced.
Further, a plating solution is prevented from passing through a
large number of through-holes formed in the regulation plate
provided in the plating tank 186. Accordingly, non-uniform metal
film thickness is prevented from being formed on the surface of the
plating workpiece due to influence of a flow of the plating
solution.
[0138] FIG. 20 shows a plating apparatus 170a according to another
embodiment of the present invention, and FIGS. 21A and 21B show a
regulation plate and a cylindrical member forming a plating
solution passage which are used in the plating apparatus 170a. The
plating apparatus 170a differs from the apparatus shown in FIGS. 3
through 5 in that the plating apparatus 170a employs a regulation
plate 60 having a thickness of, for example, about 0.5 to 10 mm and
having a central hole 60a at the center thereof which faces a
substrate W held by a substrate holder 160 and has an inside
diameter D corresponding to the outside diameter of the substrate
W, and that a cylindrical member 200 having an inside diameter
equal to the inside diameter D of the central hole 60a is
concentrically connected to a surface of the regulation plate 60 on
the substrate holder 160 side continuously (i.e., concentrically)
with the central hole 60a so as to define a plating solution
passage 200a inside an inner circumferential surface of the
cylindrical member 200 for allowing an electric field to pass
uniformly therethrough and allowing a plating solution 10 to pass
therethrough. As with the regulation plate 60, the cylindrical
member 200 is made of a dielectric material including PVC, PP,
PEEK, PES, HT-PVC, PFA, PTFE, and other resin materials. Other
constructions are the same as those shown in FIGS. 3 through 5.
[0139] The inside diameters D of the central hole of the regulation
plate 60 and the cylindrical member 200 are generally set to be
approximately in a range of .+-.10 mm of an outside diameter
(plated surface outside diameter) of a surface of a substrate W to
be plated, preferably in a range of .+-.5 mm of an outside diameter
of a surface to be plated, more preferably in a range of .+-.1 mm
of an outside diameter of a surface to be plated. The length L of
the cylindrical member 200 may properly be set depending upon the
shape of the plating tank 186, the distance between the anode 56
and the substrate W, and the like. However, the length L is
generally set to be in a range of 10 to 90 mm, preferably 20 to 75
mm, more preferably 30 to 60 mm.
[0140] Thus, an electric field produced between the anode 56 and
the substrate W in the plating tank 186 passes along the plating
solution passage 200a, i.e., passes uniformly through the
cylindrical member 200 without leaking out of the cylindrical
member 200. Accordingly, distortion and deviation of the electric
field can be adjusted and corrected so as to equalize a potential
distribution over the entire surface of the substrate W. As a
result, as shown in FIG. 22, a metal film P having an enhanced
within wafer uniformity can be formed on the surface of the
substrate W although it has a slightly thicker film at an edge
portion of the substrate W.
[0141] Specifically, a regulation plate 60 generally is as thin as
about 0.5 to 10 mm. Therefore, with a regulation plate 60 having
only a central hole 60a formed therein, an electric field produced
between the anode 56 and a substrate W in the plating tank 186 is
not sufficiently regulated, and distortion or deviation of an
electric field is caused. Accordingly, the substrate tends to be
thicker at an edge portion, which serves as an electrically
receiving portion. According to the present example, passing of an
electric field is regulated over the length L of the cylindrical
member 200, so that the above drawback is solved. Thus, a within
wafer uniformity of a metal film can be enhanced.
[0142] In this example, as in the examples shown in FIGS. 3 through
5, a paddle-type agitating mechanism 64 having a plurality of
paddles 62 extending vertically downward is disposed between the
cylindrical member 200 and the substrate W held by the substrate
holder 160. The paddle-type agitating mechanism 64 is operated
during plating so as to reciprocate the paddles 62 along the
surface of the substrate W, thereby agitating the plating solution
10 in a substrate side chamber 40b. Accordingly, the directionality
of the flow of the plating solution can be eliminated, and
simultaneously sufficient ions can be supplied more uniformly to
the surface of the substrate W. Therefore, a metal film having a
more uniform thickness can be formed more rapidly.
[0143] FIG. 23 shows a plating apparatus 170b according to still
another embodiment of the present invention. The plating apparatus
170b differs from the apparatus shown in FIGS. 21 and 22 in that a
plating solution injection type agitating mechanism 202 is disposed
between the cylindrical member 200 and a substrate W held by the
substrate holder 160 instead of the paddle-type agitating mechanism
64. Specifically, the plating solution injection type agitating
mechanism 202 has a plating solution supply pipe 204, for example,
in a ring shape, communicating with a circulation pipe 48 and
immersed in the plating solution 10 in the plating tank 186, and a
plurality of plating solution injection nozzles 206 attached to
predetermined portions of the plating solution supply pipe 204
along a circumferential direction for ejecting the plating solution
10 toward the substrate W held by the substrate holder 160. A
plating solution 10 fed by a pump 50 is supplied to the plating
solution supply pipe 204 and injected from the plating solution
injection nozzles 206 toward the substrate. Thus, the plating
solution 10 is introduced into the plating tank 186, overflows
upper ends of overflow weirs 44, and is circulated.
[0144] Thus, the plating solution 10 is injected from a plurality
of plating solution injection nozzles 206 toward the substrate W.
Accordingly, the plating solution 10 in the plating tank 186 can be
agitated so as to make the plating solution concentration uniform
and, simultaneously, to sufficiently supply components of the
plating solution 10 to the substrate W. Thus, a metal film having a
more uniform thickness can be formed more rapidly.
[0145] In this example, the cylindrical member 200 is coupled to a
surface of the regulation plate 60 on the substrate W side.
However, as shown in FIG. 24B, an insertion hole 60b may be formed
in the regulation plate 60, and a cylindrical member 200 having an
inside diameter D, a length L, and a plating solution passage 200a
inside an inner circumferential surface thereof may be inserted
into the insertion hole 60b. In this manner, the cylindrical member
200 may be held at a predetermined position along a longitudinal
direction of the cylindrical member 200. This arrangement ensures a
sufficient length L as the cylindrical member 200 even if a
distance between the regulation plate 60 and the paddles 62 (see
FIG. 20) or the plating solution supply pipe 204 (see FIG. 23) is
short.
[0146] Further, as shown in FIGS. 25A and 25B, the cylindrical
member 200 may have a circumferential wall having a large number of
through-holes 200b which have a size such as to prevent leakage of
an electric field. With this arrangement, the plating solution 10
can pass through the through-holes 200b formed in the
circumferential wall of the cylindrical member 200 while preventing
leakage of the electric field. Accordingly, the concentration of
the plating solution is prevented from being different between the
inside and outside of the cylindrical member 200. With respect to
the shape of the through-holes, besides fine holes as in this
example, slit-like elongated holes, cross holes extending
vertically and horizontally, and a combination thereof may be
exemplified.
[0147] Further, as shown in FIGS. 26A and 26B, a regulation plate
210 may be formed by a plate having a sufficient thickness, and a
through-hole having a predetermined inside diameter may be formed
at a predetermined position in the regulation plate 210 so that the
through-hole serves as a plating solution passage 210a having a
predetermined inside diameter D and a predetermined length L. In
such a case, the number of parts can be reduced.
[0148] Furthermore, as shown in FIGS. 27A and 27B, a rectangular
block 212 having a sufficient thickness may be prepared so that a
through-hole formed in the rectangular block 212 serves as a
plating solution passage 210a having a predetermined inside
diameter D and a predetermined length L, and the rectangular block
212 may be connected to a surface of a regulation plate 60 having a
center hole 60a on the substrate W side.
[0149] FIG. 28 shows a plating apparatus 170c according to yet
another embodiment of the present invention, and FIGS. 29A and 29B
shows a regulation plate, a cylindrical member forming a plating
solution passage, and an electric field adjustment ring which are
used in the plating apparatus 170c shown in FIG. 28. The plating
apparatus 170c differs from the apparatus shown in FIGS. 20 and 21
in the following points: An electric field adjustment ring 220
having the same inside diameter D as an inside diameter of the
cylindrical member 200 and a width A is concentrically attached to
a substrate W side end surface of the cylindrical member 200 having
a plating solution passage 200a defined inside an inner
circumferential surface thereof. The electric field adjustment ring
220 is disposed close to a substrate W with a gap G1. Further, the
paddle-type agitating mechanism 64 having a plurality of paddles 62
extending vertically downward is disposed between the anode 56 and
the regulation plate 60 in the anode side chamber 40a so as to
reciprocate the paddles 62 in parallel to the substrate W held by
the substrate holder 160, thereby agitating the plating solution.
Thus, the paddle-type agitating mechanism 64 agitates the plating
solution 10 in the anode side chamber 40a. Other constructions are
the same as those shown in FIGS. 20 and 21.
[0150] As with the regulation plate 60 and the cylindrical member
200, the electric field adjustment ring 220 is made of a dielectric
material including PVC, PP, PEEK, PES, HT-PVC, PFA, PTFE, and other
resin materials. Other elements of the construction are the same as
those shown in FIGS. 3 through 5. The shape of the electric field
adjustment ring 220 may properly be set depending upon the shapes
of the plating tank 186 and the substrate W, the distance between
the anode 56 and the substrate W, and the like. However, the width
A is generally set to be in a range of 1 to 20 mm, preferably 3 to
17 mm, more preferably 5 to 15 mm. A gap G1 between the electric
field adjustment ring 220 and the substrate W is generally set to
be in a range of 0.5 to 30 mm, preferably 1 to 15 mm, more
preferably 1.5 to 6 mm.
[0151] The electric field adjustment ring 220 serves to adjust an
electric field at a peripheral portion of the substrate W by
covering a location near a peripheral portion of a substrate W over
a predetermined width. Thus, an electric field is adjusted at a
peripheral portion of the substrate W. Accordingly, an electric
field produced between the anode 56 and the substrate W can be made
uniform over the entire surface of the substrate W, including an
edge portion of the substrate W, which serves as an electrically
receiving portion. Therefore, as shown in FIG. 30, a metal film P
having an enhanced within wafer uniformity can be formed on the
surface of the substrate W, including the edge portion of the
substrate.
[0152] FIG. 31 shows a plating apparatus 170d according to yet
another embodiment of the present invention. The plating apparatus
170d has a plating solution injection type agitating mechanism 202,
which is shown in FIG. 23, disposed between the anode 56 and the
regulation plate 60 in the anode side chamber 40a, instead of the
paddle-type agitating mechanism 64 used in the plating apparatus
shown in FIGS. 28 and 29. Specifically, in this example, a plating
solution 10 fed by a pump 50 is supplied to the plating solution
supply pipe 204 and injected from the plating solution injection
nozzles 206 toward a plating solution passage 200a of the
cylindrical member 200. Thus, the plating solution 10 is introduced
into the plating tank 186, overflows upper ends of overflow weirs
44, and is circulated. Other elements of the construction are the
same as those shown in FIGS. 28 and 29.
[0153] Thus, the plating solution injection type agitating
mechanism 202 is disposed in the anode side chamber 40a, and the
plating solution is injected from the plating solution injection
nozzles 206 toward the plating solution passage 200a of the
cylindrical member 200. The plating solution can be supplied
through the plating solution passage 200a to the substrate W held
by the substrate holder 160 even if a gap G1 between an electric
field adjustment ring 220 and the substrate W held by the substrate
160 is narrow.
[0154] As shown in FIGS. 32A and 32B, an insertion hole 60b may be
formed in the regulation plate 60, and a cylindrical member 200
having an inside diameter D, a length L, a plating solution passage
200a inside an inner circumferential surface thereof, and an
electric field adjustment ring 220 attached to an end surface
thereof may be inserted into the insertion hole 60b substantially
in the same manner as shown in FIGS. 24A and 24B. Thus, the
cylindrical member 200 may be held at a predetermined position
along a longitudinal direction of the cylindrical member 200.
[0155] As shown in FIGS. 33A and 33B, a large number of
through-holes 200b having a size such as to prevent leakage of an
electric field may be formed in a circumferential wall of a
cylindrical member 200 having an electric field adjustment ring 220
attached to an end surface thereof substantially in the same manner
as shown in FIGS. 25A and 25B. Thus, the plating solution 10 can
pass through the through-holes 200b formed in the circumferential
wall of the cylindrical member 200 while preventing leakage of the
electric field.
[0156] Further, as shown in FIGS. 34A and 34B, the electric field
adjustment ring 220 may not be fixed to the end surface of the
cylindrical member 200, but may be supported by a support 222 so as
to have a gap G2 between the front of the substrate W side end
surface of the cylindrical member 200 and the substrate W. As with
the gap G1 between the electric field adjustment ring 220 and the
substrate W, the gap G2 is generally set to be in a range of 0.5 to
30 mm, preferably 1 to 15 mm, more preferably 1.5 to 6 mm. With the
plating solution passage 200a thus formed, the cylindrical member
200 and the electric field adjustment ring 220 can be separated so
as to offer a broader choice.
[0157] As shown in FIGS. 35A and 35B, a plating solution passage
224a having a predetermined inside diameter D and a length L may be
defined by an inner circumferential surface of a thick ring 224
having a sufficient thickness, and an electric field adjustment
ring 224b having a predetermined width A may be formed by a
substrate side end surface of the thick ring 224. In this case, the
number of parts can be reduced.
[0158] Although the aforementioned examples show that the present
invention is applied to a so-called dipping type plating apparatus,
the present invention is also applicable to a face-down type
plating apparatus or a face-up type plating apparatus.
[0159] FIG. 36 shows an example in which the present invention is
applied to a face-down type plating apparatus. In this example, the
following structures are added to a conventional plating apparatus
shown in FIG. 37. Specifically, a regulation plate 230 having a
central hole 230a formed therein is disposed at an upper position
of the plating tank 12 so as to separate the interior of the
plating tank 12 into an anode side chamber 12a and a substrate side
chamber 12b. Further, a cylindrical member 232 having an inside
diameter equal to the diameter of the central hole 230a and an
inner circumferential surface forming a plating solution passage
232a is concentrically attached to an upper surface of the
regulation plate 230 in a manner so as to project upward. With this
arrangement, an electric field produced between the anode 16 and a
substrate W in the plating tank 12 can pass along the plating
solution passage 232a, i.e. uniformly through the cylindrical
member 232 without leaking out of the cylindrical member 232.
Accordingly, distortion and deviation of the electric field can be
adjusted and corrected so as to equalize a potential distribution
over the entire surface of the substrate W.
[0160] An electric field adjustment ring having an inside diameter
equal to an inside diameter of the cylindrical member and a
predetermined width may concentrically be attached to an upper end
surface of the cylindrical member so as to cover a location near a
peripheral portion of the substrate W over a predetermined width.
Thus, an electric field can be adjusted at the peripheral portion
of the substrate W. Accordingly, an electric field produced between
the anode 56 and the substrate can be made uniform over the entire
surface of the substrate, including an edge portion of the
substrate, which serves as an electrically receiving portion.
Therefore, a metal film having an enhanced within wafer uniformity
can be formed on the surface of the substrate, including the edge
portion of the substrate.
* * * * *