U.S. patent application number 10/843557 was filed with the patent office on 2004-12-09 for apparatus and method for plating a substrate.
Invention is credited to Endo, Yasuhiko, Kuriyama, Fumio, Sekimoto, Masahiko, Strausser, Stephen.
Application Number | 20040245112 10/843557 |
Document ID | / |
Family ID | 33487292 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040245112 |
Kind Code |
A1 |
Sekimoto, Masahiko ; et
al. |
December 9, 2004 |
Apparatus and method for plating a substrate
Abstract
The present invention is directed to a plating apparatus and
method in which bubbles generated at the plating surfaces are
easily removed and the uniformity of the thickness of the plated
film within the plated surface can be improved. The plating
apparatus comprises a cassette table for loading a cassette in
which a substrate having a plating surface is contained. An aligner
for aligning the substrate, a rinser-dryer for rinsing and drying
the substrate, and a plating unit for plating the substrate are
also provided. The plating unit comprises a plating vessel
containing a plating solution, a holder for holding the substrate
to immerse the substrate in the plating solution in the plating
vessel. The plating surface is exposed to a nozzle which ejects the
plating solution toward the plating surface.
Inventors: |
Sekimoto, Masahiko; (Tokyo,
JP) ; Kuriyama, Fumio; (Tokyo, JP) ; Endo,
Yasuhiko; (Tokyo, JP) ; Strausser, Stephen;
(Austin, TX) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
33487292 |
Appl. No.: |
10/843557 |
Filed: |
May 12, 2004 |
Current U.S.
Class: |
205/133 ;
204/224R; 204/274; 205/80 |
Current CPC
Class: |
C25D 5/08 20130101 |
Class at
Publication: |
205/133 ;
204/274; 204/224.00R; 205/080 |
International
Class: |
C25D 005/00; C25D
005/08; C25D 017/00; C25C 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 29, 2003 |
JP |
JP2003-153420 |
Claims
1. An apparatus for plating a substrate, said substrate having a
plating surface to be plated, said apparatus comprising: a cassette
table for loading a cassette containing therein a substrate; an
aligner for aligning said substrate; a rinser-dryer for rinsing and
drying said substrate; and a plating unit for plating said
substrate, said plating unit comprising a plating vessel containing
a plating solution, a holder for holding said substrate while being
immersed in said plating solution in said plating vessel so as to
expose said plating surface to said plating solution, and a nozzle
for ejecting said plating solution toward said plating surface.
2. The apparatus of claim 1, wherein said nozzle is movable
parallel to said plating surface.
3. The apparatus of claim 1, wherein said nozzle is provided
between an anode, which is placed within said plating vessel to
confront said plating surface, and said plating surface.
4. The apparatus of claim 1, wherein said nozzle is provided on a
puddle movably arranged within said plating vessel for agitating
said plating solution within said plating vessel.
5. The apparatus of claim 1, wherein said nozzle is provided on a
regulation plate arranged between an anode placed in said plating
vessel and said plating surface.
6. The apparatus of claim 1, wherein an ejecting angle of said
nozzle relative to said plating surface is adjustable.
7. The apparatus of claim 1, wherein said nozzle is supplied with a
plating solution within said plating vessel circulated by a
circulation line.
8. The apparatus of claim 1, wherein said nozzle is provided with a
flow controller for controlling a flow rate of said plating
solution ejected by said nozzle.
9. The apparatus of claim 1, wherein said nozzle comprises a nozzle
assembly comprising a plurality of nozzles.
10. A method of plating a substrate having a plating surface to be
plated, said method comprising: holding said substrate with a
substrate holder; immersing said holder in a plating solution
contained in a plating vessel so as to expose said plating surface
to said plating solution; placing a nozzle in said plating vessel
to confront to said plating surface; ejecting a plating solution
from said nozzle toward said plating surface.
11. The method of claim 10, wherein aid nozzle is moved while
ejecting said plating solution.
12. An apparatus for plating a substrate having a plating surface
to be plated, said apparatus comprising: a plating vessel
containing a plating solution; a holder for holding said substrate
while exposing said plating surface to said plating solution within
said plating vessel; a nozzle provided in said plating vessel for
ejecting a plating solution toward said plating surface.
13. The apparatus of claim 12, wherein said nozzle is movable
relative to said plating surface.
14. The apparatus of claim 12, wherein said nozzle is arranged to
eject said plating solution at a substantially right angle relative
to said plating surface.
15. The apparatus of claim 12, wherein said nozzle is arranged to
eject said plating solution at an oblique angle relative to said
plating surface.
16. An apparatus for plating a substrate having a plating surface
to be plated, said apparatus comprising: a plating vessel
accommodating a plating solution and an anode therein and having a
lateral opening; a substrate holder for holding said substrate
while exposing said plating surface to said plating solution within
said plating vessel and sealing said substrate to prevent
infiltration of plating solution to a surface of said substrate
other than said exposed plating surface; and holder driving
assembly for driving said substrate holder to a position where said
plating surface covers said opening of said plating vessel.
17. The apparatus of claim 16, wherein said substrate holder is
laterally slidable.
18. The apparatus of claim 16, wherein said plating vessel
comprises a weir member for confining a reservoir surrounding said
anode within said plating vessel, which can contain plating
solution therein for immersing said anode.
19. The apparatus of claim 18, further comprising an auxiliary
plating solution supply system for circulating said plating
solution within said reservoir chamber.
20. The apparatus of claim 16, further comprising a rapid drain
system for rapidly draining plating solution from said plating
vessel.
21. The apparatus of claim 16, further comprising a nozzle for
ejecting plating solution toward said plating surface of said
substrate held by said substrate holder.
22. The apparatus of claim 16, wherein said substrate holder
comprises a detachable seal unit comprising a seal ring and a
cathode integrated together.
23. The apparatus of claim 22, wherein said seal unit comprises a
seal member for water-tightly sealing said opening of said plating
vessel.
24. A method of plating a substrate having a plating surface to be
plated, said method comprising: accommodating a plating solution
and an anode in a plating vessel having a lateral opening; holding
said substrate with a substrate holder while exposing said plating
surface to said plating solution within said plating vessel and
sealing said substrate to prevent infiltration of plating solution
to a surface of said substrate other than said exposed plating
surface; and driving said substrate holder to a position where said
plating surface covers said opening of said plating vessel.
25. The method of claim 24, wherein said plating vessel comprises a
weir member for confining a reservoir surrounding said anode within
said plating vessel, said method comprising immersing said anode by
introducing plating solution within said reservoir.
26. The method of claim 24, further comprising rapidly draining
plating solution from said plating vessel after plating is
finished.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus and method for
plating a substrate, and more particularly to an apparatus and
method used for plating metal films on a surface of a substrate
such as a semiconductor wafer having fine interconnection grooves,
holes or apertures of resist films thereon, or for forming solder
bumps or protruding electrodes for electrically connecting to
electrodes of semiconductor chip packages.
[0003] 2. Description of the Related Art
[0004] In a TAB (Tape Automated Bonding) process or "flip-chip"
process, the surface of a semiconductor chip having interconnects
is formed with bumps or protruding electrodes comprised of gold,
copper, solder, or nickel, or a layered structure of the
above-mentioned materials, for electrically connecting with other
chip package electrodes or TAB electrodes.
[0005] Such bumps can be formed by processes such as
electroplating, vapor deposition, printing, and ball-bumping.
Recent trends of increasing number in I/O terminals on
semiconductor chips, and smaller pitches of interconnections have
lead to a wide use of electroplating, which can provide a fine
structure metallization and relatively stable operation.
[0006] Electroplating processes can be generally categorized in two
types; a fountain type or cup type process in which a substrate
such as a semiconductor wafer is plated while the surface to be
plated faces downward and a plating solution flows upward to
metallize the surface; and a dip type process in which the
substrate is vertically placed in a plating vessel (container,
cell, or the like) and the solution is supplied from the bottom to
overflow from the top of the plating vessel.
[0007] FIG. 28 shows an example of a conventional dip type
electroplating unit. The electroplating unit comprises: a substrate
holder 10 for detachably holding a substrate W such as
semiconductor wafer; a plating vessel 16 containing a plating
solution 12, in which the substrate W supported by a substrate
holder 10 and an anode 14 are immersed so as to confront each
other; and a power source 18 for applying plating voltage between
the anode 14 and feeder layer (seed layer) formed on the surface to
be plated of the substrate W to supply plating current. An overflow
vessel 22 is provided beside the plating vessel 16 for receiving a
plating solution 12 which has flown over an upper edge of an
overflow weir 20 of the plating vessel 16. The overflow vessel 22
and the plating vessel 16 is communicated through a circulation
line 24 provided with a circulation pump 26, a thermostat unit 28,
and a filter 30. Thus, the plating solution 12 driven by the
circulation pump 26 is supplied to and fills the plating vessel 16,
and then overflows the weir 20 to flow into the overflow vessel 22
and returns to the circulation pump 26 for circulation.
[0008] With the plating unit, and by supplying the plating solution
12 into the plating vessel 16 from the bottom portion to overflow
the weir 20, arranging the substrate holder 10 in the plating
solution 12 within the plating vessel 16 so as to confront the
anode 14, and applying prescribed plating voltage between the anode
14 and the substrate W, a plated film is formed on the surface of
the substrate W.
[0009] A plurality of puddles (agitating rods) are vertically
suspended from a lower surface of a puddle shaft 32, which is
arranged above the plating vessel 16, horizontally between the
substrate holder 10 and the anode 14, and parallel to their
surfaces. The puddles are reciprocated horizontally in a direction
parallel to the substrate W via the puddle shaft 32 to agitate the
plating solution 12 within the plating vessel 16, so as to
facilitate the formation of a plating film with uniform
thickness.
[0010] Also, the substrate holder 10 used in the conventional dip
type electroplating unit can detachably holds the substrate W while
sealing the peripheral edge surface and the rear surface to expose
the front surface to be plated. The substrate W is immersed in the
plating solution 12 together with the holder for plating.
[0011] It is necessary to securely seal the peripheral portion of
the substrate to prevent the plating solution from infiltrating to
the rear surface of the substrate which confront the surface to be
plated when the holder is immersed into the plating solution. A
conventional substrate holder comprises a pair of supports (holding
members) which are open-and closeable to each other, and one
support is provided with a fixer ring. The substrate holder is used
to hold a substrate by driving the fixer ring to rotate, while the
substrate is held between the supports, to push the one support
toward the other so that the a seal ring attached to the one
support is pressed against the peripheral region of the substrate
surface for sealing.
[0012] When the substrate is subjected to a series of steps
including plating and other accompanying processes, the substrate
is held by the holder and the holder having the substrate is
transferred to plating or processing vessels, and the substrate is
immersed into the plating solution or other processing solutions
together with the holder.
SUMMARY OF THE INVENTION
[0013] The first object of this invention is to provide a plating
apparatus and method in which bubbles generated at the plating
surfaces are easily removed and the uniformity of the thickness of
the plated film within the plated surface can be improved by
controlling the flow of the plating solution within the plating
vessel.
[0014] Another object of the invention is to provide a plating
apparatus and method which can plate a substrate while the
peripheral portion is securely sealed, which is suitable for a
small number and small lot production, and can facilitate to
produce a compact plating apparatus.
[0015] An apparatus for plating a substrate having a plating
surface to be plated in accordance with one aspect of the present
invention comprises: a cassette table for loading a cassette
containing therein a substrate; an aligner for aligning the
substrate; a rinser-dryer for rinsing and drying the substrate; and
a plating unit for plating the substrate, the plating unit
comprising a plating vessel containing a plating solution, a holder
for holding the substrate while being immersed in the plating
solution in the plating vessel so as to expose the plating surface
to the plating solution, and a nozzle for ejecting the plating
solution toward the plating surface.
[0016] The nozzle may be movable parallel to the plating
surface.
[0017] The nozzle may be provided between an anode placed within
the plating vessel to confront the plating surface, and the nozzle
may be provided between the anode and the plating surface.
[0018] The nozzle may be provided on a puddle, which is movably
arranged within the plating vessel for agitating the plating
solution within the plating vessel.
[0019] The nozzle may be provided on a regulation plate arranged
between an anode placed in the plating vessel and the plating
surface.
[0020] An ejecting angle of the nozzle relative to the plating
surface may be adjustable.
[0021] The nozzle may be supplied with a plating solution within
the plating vessel circulated by a circulation line.
[0022] The nozzle may be provided with a flow controller for
controlling a flow rate of the plating solution ejected by the
nozzle.
[0023] The nozzle may comprise a nozzle assembly comprising a
plurality of nozzles.
[0024] A method of plating a substrate having a plating surface to
be plated in accordance with one aspect of the present invention
comprises: holding the substrate with a substrate holder; immersing
the holder in a plating solution contained in a plating vessel so
as to expose the plating surface to the plating solution; placing a
nozzle in the plating vessel to confront to the plating surface;
ejecting a plating solution from the nozzle toward the plating
surface.
[0025] An apparatus for plating a substrate having a plating
surface to be plated in accordance with another aspect of the
present invention comprises: a plating vessel containing a plating
solution; a holder for holding the substrate while exposing the
plating surface to the plating solution within the plating vessel;
a nozzle provided in the plating vessel to confront to the plating
surface for ejecting a plating solution toward the plating
surface.
[0026] The nozzle may be movable relative to the plating
surface.
[0027] The nozzle may be arranged to eject the plating solution at
a substantially right angle relative to the plating surface.
[0028] The nozzle may be arranged to eject the plating solution at
an oblique angle relative to the plating surface.
[0029] An apparatus for plating a substrate having a plating
surface to be plated in accordance with another aspect of the
present invention comprises: a plating vessel accommodating a
plating solution and an anode therein and having a lateral opening;
a substrate holder for holding the substrate while exposing the
plating surface to the plating solution within the plating vessel
and sealing the substrate to prevent infiltration of plating
solution to a surface of the substrate other than the exposed
plating surface; and a holder driving assembly for driving the
substrate holder to a position where the plating surface covers the
opening of the plating vessel.
[0030] The substrate holder may be laterally slidable.
[0031] The plating vessel may comprise a weir member for confining
a reservoir surrounding the anode within the plating vessel, which
can contain plating solution therein for immersing the anode.
[0032] The apparatus may further comprise an auxiliary plating
solution supply system for circulating the plating solution within
the reservoir chamber.
[0033] The apparatus may further comprise a rapid drain system for
rapidly draining plating solution from the plating vessel.
[0034] The apparatus may further comprise a nozzle for ejecting
plating solution toward the plating surface of the substrate held
by the substrate holder.
[0035] The substrate holder may comprise a detachable seal unit
comprising a seal ring and a cathode integrated together.
[0036] The seal unit may comprise a seal member for water-tightly
sealing the opening of the plating vessel.
[0037] A method of plating a substrate having a plating surface to
be plated, the method comprising: accommodating a plating solution
and an anode in a plating vessel having a lateral opening; holding
the substrate with a substrate holder while exposing the plating
surface to the plating solution within the plating vessel and
sealing the substrate to prevent infiltration of plating solution
to a surface of the substrate other than the exposed plating
surface; and driving the substrate holder to a position where the
plating surface covers the opening of the plating vessel.
[0038] The plating vessel may comprise a weir member for confining
a reservoir surrounding the anode within the plating vessel, the
method comprising immersing the anode by introducing plating
solution within the reservoir.
[0039] The method may further comprise rapidly draining plating
solution from the plating vessel after plating is finished.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 is a vertical cross-sectional view of an embodiment
of the present invention applied to an electroplating unit;
[0041] FIG. 2 is a plan view of the plating apparatus shown in FIG.
1;
[0042] FIG. 3 is an enlarged view of another embodiment of a
nozzle;
[0043] FIG. 4 is a plan view of another embodiment of the present
invention applied to an electroless plating unit;
[0044] FIG. 5 is a vertical cross-sectional view of another
embodiment of the present invention applied to an electroplating
unit;
[0045] FIG. 6 is a plan view of a substrate plating apparatus
having a plating unit according to an embodiment of the present
invention;
[0046] FIG. 7 is a schematic view showing airflow within the
substrate plating apparatus of FIG. 6;
[0047] FIG. 8 is an embodiment of an interconnect formation
apparatus having an electroplating unit and electrolytic etching
unit according to the present invention;
[0048] FIG. 9 is a flow chart showing a step flow in the
interconnect formation apparatus of FIG. 8;
[0049] FIG. 10 is a cross-sectional view schematically showing the
process of plating a substrate;
[0050] FIG. 11 is a plan view of a semiconductor manufacturing
apparatus having an electroplating apparatus and an electroless
plating apparatus according to an embodiment of the present
invention;
[0051] FIGS. 12(a) to 12(c) are cross-sectional views showing the
process of making a semiconductor device;
[0052] FIG. 13 is a plan view of another plating apparatus having
an electroplating unit;
[0053] FIG. 14 is a cross-sectional view schematically showing the
process of plating a bump on a substrate;
[0054] FIG. 15 is a plan view of another plating apparatus having
an electroplating unit;
[0055] FIG. 16 is a plan view of another substrate plating
apparatus having a plating unit according to an embodiment of the
present invention;
[0056] FIG. 17 is a schematic view showing a plating unit when a
substrate is inserted in the substrate holder;
[0057] FIG. 18 is a schematic view showing a plating unit when it
is plating a substrate;
[0058] FIG. 19 is a schematic rear view showing a plating unit
during maintenance;
[0059] FIG. 20 is a schematic front view showing a plating unit
during maintenance;
[0060] FIG. 21 is a view showing a cross section of a plating
vessel and a flow diagram of a plating solution regulation supply
system;
[0061] FIG. 22 is a partial enlarged view of FIG. 21;
[0062] FIG. 23 is a vertical cross-sectional view showing a
substrate holder;
[0063] FIGS. 24(a) to 24(e) are schematic views showing the process
of holding a substrate with a substrate holder;
[0064] FIGS. 25(a) to 25(d) are schematic views showing the process
of preparing for plating a substrate while blocking an opening of a
substrate plating vessel;
[0065] FIGS. 26(a) to 26(d) are schematic views showing the process
of plating a substrate while blocking an opening of a substrate
plating vessel;
[0066] FIGS. 27(a) to 27(e) are schematic views showing the process
of plating a bump on a substrate; and
[0067] FIG. 28 is a schematic view showing a conventional substrate
plating unit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0068] Preferred embodiments of the present invention will be
described by referring to the attached drawings.
[0069] FIGS. 1 and 2 show an embodiment of the invention applied to
an electroplating unit. The electroplating unit comprises: a
vertically movable substrate holder 10 for detachably holding a
substrate W to be plated such as a semiconductor wafer; a plating
vessel or a plating cell 16 for accommodating a plating solution
12, a substrate W vertically held by the substrate holder 10, and
an anode 14 (positive electrode) so that the substrate W and anode
14 are immersed in the plating solution 12 to confront each other;
a plating power source 18 for applying plating voltage between the
anode 14 and a feeding layer (seed layer) formed on the surface to
be plated of the substrate W to supply plating current.
[0070] A plurality of puddles (agitating rods) 34 are vertically
suspended from a lower surface of a puddle shaft 32, which is
arranged above the plating vessel 16, horizontally located between
the substrate holder 10 and the anode 14, and parallel to the
surface of the substrate W. The puddle shaft 32 is provided with a
drive assembly 46 comprising a rack 40 attached to the puddle shaft
32, a worm gear 44 attached to a drive shaft of a motor 42 and
engaging with the rack 40, to thereby traverse the vessel 16 along
with normal and reverse rotations of the motor 42. Thus, the
puddles 34 also move parallel to the substrate W along with the
movement of the puddle shaft 32 to agitate the plating solution 12
within the plating vessel 16. The drive assembly 46 can be
constructed by any component such as combination of a rack and a
pinion, a linkage, or a linear slider.
[0071] Plating solution nozzles 48 are provided to each of the
puddles 34 at the edge facing the substrate W held by the holder 10
and at mutual distances along a vertical direction to open toward
the substrate W held by the holder 10 for ejecting or spurting the
plating solution.12 thereto. Within the puddle shaft 32 and each of
the puddles 36, plating solution passages 50 are provided to
mutually communicate and reach to the plating solution nozzles 48.
The plating solution passages 50 have an open end connected to a
plating solution circulation line 56 having a circulation pump 52
and a flow regulator 54, and the other end of the plating solution
circulation line 56 is opening in the plating vessel 16. Thus, the
plating solution 12 within the plating vessel 16 is pumped up by
the circulation pump 52 and the flow rate in the circulation line
56 is adjusted by the flow regulator 54. The plating solution 12 is
then supplied to each nozzles 48 through the line 50 to be ejected
toward the substrate W held by the holder 10.
[0072] Since the nozzles 48 are provided on the puddle 34 which
reciprocates parallel to the substrate W to agitate the plating
solution 12 within the plating vessel 16, different members for
carrying and moving the plating solution nozzles 48 are not
necessary so as to simplify the structure of the unit.
[0073] Although the embodiment uses a flow regulator 54 as a flow
regulating device for plating solution 12, this can be dispensed
with by using a positive displacement pump which may dual-purposely
function as a flow regulator. Also, the embodiment employs a
straight nozzle system in which the plating solution 12 is linearly
ejected from the nozzle 48, different system can be used such as a
showering system in which the solution is sprayed in a shower or as
an atomized mist.
[0074] The plating process by the above described plating unit will
be explained below. Initially, a predetermined amount of plating
solution 12 is supplied to the plating vessel 16, and the holder 10
holding a substrate W is lowered to a predetermined position where
the substrate W confronts the anode 14 readily immersed in the
plating solution 12. Then, a predetermined plating voltage is
applied between the anode 14 and the substrate W by the plating
power source 18 for forming a plating film on the substrate
surface. The drive assembly 46 drives the puddle 34 to
reciprocatingly traverse the bath within the vessel 16 parallel to
the substrate W to agitate the plating solution 12, and the
circulation pump 52 is simultaneously driven to eject the plating
solution 12 from the nozzles 48 toward the substrate W held by the
holder 10.
[0075] Such processes of agitation of the plating solution 12 by
the reciprocating puddles 34 and ejecting of the plating solution
12 from the nozzles 48 are synchronized with the reciprocating
movement of the puddles 34 and provides adequate amount of ions
uniformly to the substrate W while directing the ejecting flow of
the plating solution 12 against the substrate W from approximately
orthogonal direction, thereby facilitating thickness uniformity of
the plating film within the plated area.
[0076] After the plating process is finished, the anode 14 and the
substrate W are disconnected from the plating power source 18, and
the holder 10 carrying the substrate W is lifted out of the plating
vessel 16. After treating necessary processes such as rinsing with
deionized water, the plated substrate W is transferred to a next
stage.
[0077] The puddles 34 may be attached to the puddle shaft 32
through a ball joint, e.g., so that the attachment angle of the
puddle 34 is adjustable for enabling adjustment of the angle of the
plating solution 12 ejecting from the nozzle relative to the
substrate surface. Thus, the angle of the plating solution 12
bumping to the substrate surface can be optionally adjusted in
accordance with the dimension of the recesses formed on the
substrate surface, e.g., to make the plating solution 12
effectively contact the recess surface.
[0078] The apparatus can be provided with an overflow vessel as
shown in a conventional apparatus of FIG. 28, and make the plating
solution 12 having flown into the overflow vessel be ejected from
the nozzles to thereafter be circulated.
[0079] FIG. 4 shows another embodiment of the present invention
applied to an electroless plating unit. This embodiment is
different from the first embodiment in not having an anode 14 and a
power source 18 since electroless plating does not use electricity
and in using an electroless plating solution including reducing
agent as the plating solution 12 for deposition of a metal film.
Other structure is the same as the previously described
embodiment.
[0080] FIG. 5 shows another embodiment of the present invention
applied to an electroplating unit. In the embodiment, a regulation
plate 60 having a central aperture 60a of a size conforming to that
of the substrate W is arranged between the substrate W held by the
holder 10 and the anode 14. The regulation plate 60 having the
central aperture 60a is widely used in the industry which functions
to locally decrease the potential at the periphery of the substrate
surface held by the holder 10 to thereby provide more uniform film
thickness distribution. In the embodiment, four nozzles 48 are
provided on the surface of the regulation plate 60 facing the
holder 10 at locations proximate to the central aperture 60a and at
catercorner locations, for example, for ejecting plating solution
12 toward the substrate W held by the holder 10. The nozzles 48 may
be provided on the inner surface of the central aperture 60a.
Plating solution passages (not shown) are provided within the
regulation plate 60 which communicate with the nozzles 48. The
puddles 34 can be provided between the regulation plate 60 and the
holder 10.
[0081] In the embodiment, the regulation plate 60 which is
generally used for the electroplating units is also used as a
member for supporting nozzles 48 so that the nozzles 48 can be
arranged at their positions by a relatively simple structure.
[0082] FIG. 6 is a plan view of a plating apparatus comprising the
above-described plating unit. The plating apparatus comprises: a
loading/unloading unit 510; a pair of cleaning/drying process units
512; a pair of first substrate stages 514; a pair of
bevel-etching/chemical-cl- eaning units 516; a pair of second
substrate stages 518; a water-cleaning unit 520 capable of
reversing the substrate 180 degrees; and four plating process units
(electroplating units) 522. The plating apparatus further
comprises; a first transfer unit 524 for transferring the substrate
W between the loading/unloading unit 510, the cleaning/drying
process units 512, and the first substrate stages 514; a second
transfer unit 526 for transferring the substrate W between the
first substrate stages 514, the bevel-etching/chemical-cleaning
units 516, and the second substrate stages 518; and a third
transfer unit 528 for transferring the substrate W between the
second substrate stages 518, the water-cleaning unit 520, and the
plating process units 522.
[0083] Interior of the plating apparatus is partitioned by a
partition wall 523 into a plating space 530 and a clean space 540,
and these spaces 530, 540 are capable of being independently
air-supplied and exhausted. The partition wall 523 is provided with
an open/closeable shutter (not shown). The pressure within the
clean space 540 is conditioned lower than the atmospheric pressure
and higher than the plating space 530 pressure so that the air
within the clean space 540 does not flow out of the plating
apparatus and air within the plating space 530 does not flow into
the clean space 540.
[0084] FIG. 7 shows air flows within the substrate plating
apparatus. As shown in FIG. 7, fresh air is introduced from the
exterior through a duct 543, forced through high-performance
filters 544 by fans into the clean space 540, and supplied from the
ceiling 545a as downward clean air flows around the cleaning/drying
units 512 and the bevel-etching/chemical-clean- ing units 516. Most
of the supplied clean air is returned from a floor 545b through a
circulation duct 552 to the ceiling 545a, from which the clean air
is forced again through the filters 544 by the fans into the clean
space 540 to be circulated within the clean space 540. A part of
the clean air is exhausted from the cleaning/drying units 512 and
the bevel-etching/chemical-cleaning units 516 through a duct 546 to
the exterior. Thus, the clean space 540 pressure is conditioned
lower than the atmospheric pressure.
[0085] Even though the plating space 530 is dirty and not a clean
space due to the water-cleaning units 520 and the plating process
units 522, particles are not allowed to adhere to the surfaces of
the substrates W. To prevent particles from adhering to the
substrates W, clean air is introduced through the duct 547,
filtered by high-performance filters 544, forced into the plating
space 530 to flow downward by fans. If the entire amount of clean
downward flow air should be afforded by the supply from the
exterior, a large amount of air is necessarily introduced and
exhausted. Thus, only partial air is exhausted to the exterior
through the duct 553 for maintaining the plating space 530 pressure
lower than the clean space 540, and most of the down flow air is
provided by circulation air flowing through the circulation duct
550 extending from the floor 549b.
[0086] Thus, air having returned to the ceiling 549a through
circulation duct 550 is forced again through the high-performance
filters 544 and supplied to the plating space 530 as a clean air to
be circulated. In the process, air including chemical mists or
gases generated in the water-cleaning units 520, plating process
units 522, transfer units and a plating solution conditioning tank
551 is exhausted through the duct 553 so that the plating space 530
is maintained in a lower pressure than the clean space 540.
[0087] Thus, when the shutter (not shown) is opened, air within
these areas flows from the loading/unloading units 510, clean space
540 and to the plating space 530 in this order. The exhausted air
is discharged through the ducts 553, 546 to the exterior.
[0088] An interconnect formation apparatus comprising the
electroplating apparatus described above and an additional
electrolytic etching apparatus is shown in FIG. 8. The interconnect
formation apparatus comprises the followings in pairs:
loading/unloading units 210; cleaning/drying process units 212;
temporary storage units 214; plating units 216; water-cleaning
units 218; and etching process units 220. The interconnect
formation apparatus further comprises: a first transfer assembly
222 for transferring the substrate W between the loading/unloading
units 210, the cleaning/drying process units 212, and the temporary
storage units 214; and a second transfer assembly 224 for
transferring the substrate W between the temporary storage units
214, the plating process units 222, the water-cleaning units 218,
and the etching process units 220.
[0089] Formation process of an interconnect will be described by
further referring to FIGS. 9 and 10. To start with, a substrate W
formed with a seed layer on the surface is picked up from the
loading/unloading unit 210 by the first transfer assembly 222 to
import to the plating process unit 216 one by one via the temporary
storage unit 214 (step 1).
[0090] Then, the plating process unit 216 provides plating to the
substrate W to form a copper layer 7 on the surface of the
substrate W as shown in FIG. 10 (step 2). Plating solutions having
a superior leveling ability is selected, in consideration of
moderating a wide recess 7a on the copper layer 7, as a primary
concern, resulting from a large recess existing on the substrate
surface. Such plating solution may have a high concentration of
copper sulfate and a low concentration of sulfuric acid, and one
exemplified composition comprises 100.about.300 g/l of copper
sulfate and 10.about.100 g/l of sulfuric acid, with an additive
agent for promoting leveling ability containing
poly-alkylene-imine, 4-grade ammonium salts, or cationic dyes, for
example. The word "leveling ability" is used to mean a property
enhancing plating growth from the bottom of recesses formed on the
substrate surface.
[0091] By using the plating solution with superior leveling
ability, growth from the bottom of large recesses is enhanced, as
shown in FIG. 10, to obtain a copper layer of a film thickness t2
which is larger than the thickness t1 of a film formed on a flat
surface. Thus, the large recess can be filled with a film having a
smaller thickness t1.
[0092] The substrate W finished with plating is transferred to the
water-cleaning unit 218 when it is necessary to be water-cleaned,
and is transferred to the etching process unit 220 (step 3).
[0093] Then, the substrate W is subjected to an electrolytic
etching process in the etching process unit 220 to etch the copper
layer formed on the substrate surface (step 4). Etching solution
used here may include additive agents for promoting etching such as
pyrophoric acid, ethylene diamine, amino-carboxylic acid, EDTA,
DTPA, imino-diacetic-acid, TETA, and NTA, or additive agents for
suppressing etching such as 4-grade ammonium salts, a copper
complex compound such as polymers, organic complexes or their
derivatives, or additive agents for rendering corrosion potential
of copper ignoble such as thiocarbamide or its derivatives. The
base bath used here may comprise acids such as sulfuric acid,
hydrochloric acid, sulfuric acid hydrogen peroxide, or hydrofluoric
acid hydrogen peroxide, or alkalis such as ammonia hydrogen
peroxide, but not be limited thereto.
[0094] This etching process selectively etches the build-up
portions of the copper layer to enhance flatness of the copper
layer. Thus, the following CMP (Chemical Mechanical Planarization)
process requires less process rate so that CMP can be completed in
a shorter period while preventing generation of so called
"dishing".
[0095] Subsequently, the substrate W finished with etching is
transferred to the water-cleaning unit 218 (step 5) when it is
necessary so as to be water-cleaned, transferred to the
cleaning/drying unit to be cleaned and dried (step 6), and returned
to the cassette in the loading/unloading unit 210 by the first
transfer assembly 222 (step 7).
[0096] The plating process and etching process may be repeated to
selectively etch the build-up portion of the copper film for every
plating process, to thereby further enhance the flatness of the
copper film. While this embodiment employs a continuous process of
plating and etching performed within a same interconnect formation
apparatus, these processes can be performed individually in each
independent apparatuses.
[0097] Further, in the above embodiment, the electroplating unit
and electrolytic etching unit are individually provided to have the
same structure and are operated using different electrolytes by
applying different polarity potentials between the substrate W and
the electrode (anode or cathode). However, a single apparatus can
be used for both processes by exchanging the polarity so that the
electroplating unit can be dual-purposely used as an electrolytic
etching unit.
[0098] Next, semiconductor device manufacturing apparatus using the
electroplating unit described above will be explained by referring
to FIG. 11. This apparatus is assembled on a generally rectangular
space on a floor and comprises a first polishing unit 324a and a
second polishing unit 324b confronting each other at one end of the
space, and a pair of loading/unloading units at the other end for
placing thereon substrate cassettes 326a, 326b for carrying
substrates W such as semiconductor wafers. Along a virtual center
line or a transfer line connecting the polishing units 324a, 324b
and loading/unloading units, two transfer robots 328a, 328b are
provided. On one side of the transfer line, a first plating unit
(electroplating unit) 330, a copper film thickness inspection unit
332, and a pre-plating process unit 334 having a reversing machine
are provided. On the other side of the transfer line, a
rinsing/drying unit 336, a second (electroless) plating unit 338
for forming a protection film and a cleaning unit 339 having a
sponge roller are provided. A vertically movable pusher for
delivering substrate W to and from the polishing units 324a, 324b
are provided between the polishing units 324a, 324b and the
transfer line.
[0099] An example of an interconnect forming process using the
above-described semiconductor device manufacturing apparatus will
be described by further referring to FIG. 12. In the first place, a
semiconductor substrate W is prepared by: forming semiconductor
devices on a semiconductor substrate 1; depositing a SiO.sub.2
insulating film 2 on a conductive layer 1a; forming a contact hole
3 and a trench 4 for interconnects on the insulating film 2 by
using a lithography/etching technique; forming a barrier layer 5
comprising Ta or TaN on the inner surface of the trench 4; and
forming a seed layer 6 as a feeder layer for electroplating on the
barrier layer 5 by sputtering or the like.
[0100] The substrates W formed with the seed layer 6 are delivered
from substrate cassettes 326a, 326b by the transfer robot 328a one
by one and are transferred to the first plating unit 330. Here, a
copper layer 7 is deposited on the surface of the substrate W to
fill the trench 4. The substrate W is subjected to a hydrophilic
treatment of the surface prior to plating. This process may be
performed by using the plating unit 330 as an electrolytic etching
unit by changing the polarity of the power supplied to etch the
copper layer 7 surface as described above. After forming the copper
layer 7, the substrate W is rinsed or washed by the copper plating
unit 330, and may be dried if time allows.
[0101] Then, the substrate W is transferred to the film thickness
inspection unit 332 to measure the thickness of the plated copper
film 7, reversed if necessary, and transferred to a pusher 324
adjacent to the polishing unit 324a or 324b.
[0102] At the polishing unit 324a or 324b, the surface of the
substrate W is pressed against a polishing table while supplying
polishing solution to the polishing surface of the table to polish
the substrate surface. Polishing is finished when a finish
detection monitor has detected an endpoint. The substrate W is then
returned to the pusher 324 and washed by spraying deionized water.
Then, the substrate W is transferred to the cleaning unit 339 by
the transfer robot 328b for cleaning using a sponge roller, for
example. This process provides an interconnect comprising seed
layer 6 and a copper layer 7 in the insulating layer 2, as shown in
FIG. 12(C).
[0103] Subsequently, the substrate W is transferred to the
pretreatment unit 334 in which the substrate W is subjected to
application of Pd catalyst or removal of oxides from exposed
surfaces, and is transferred to the second plating unit 338 to
provide electroless plating. By this process, a protection film 9
comprising a Co--W--P alloy film is selectively formed by the
electroless plating process on an outer surface of the interconnect
which has been exposed through the polishing process to thereby
protect the interconnect. The thickness of the interconnect
protection film is 0.1.about.500 nm, preferably 1.about.200 nm, and
more preferably 10.about.100 nm.
[0104] After finishing the electroless plating, the substrate W is
spin-dried through high speed rotation, and is extracted from the
second plating unit 338. Then, the substrate W is transferred to
the cleaning unit 339 by the transfer robot 328b to be cleaned with
the sponge roller, and is transferred to the rinsing/drying unit
336 by the transfer robot 328a. Then, after rinsing and drying the
substrate W by the rinsing/drying unit 336, the substrate W is
returned to the same position of the substrate cassette 326a,
326b.
[0105] Another plating apparatus according to an embodiment of the
present invention is shown in FIG. 13, in which the plating vessel
16 shown in FIGS. 1 and 2 is used to form bumps on the substrates
W. The plating apparatus comprises: two cassette tables 112 for
loading a cassette 110 containing substrates W such as
semiconductor wafers; an aligner 114 for aligning the substrate W
by directing an orientation flat or notch formed on the substrate W
to a certain direction; and a spin-dryer 116 for drying the
substrate W after plating through high speed rotation, which are
arranged on a same circle. Further, a substrate mounting/demounting
unit 120 is provided along one tangential line of the circle for
mounting or demounting the substrate W from the holder 118 placed
on the unit At a central portion of these units, a transfer unit
122 comprising a transfer robot is provided to transfer the
substrate W between these units.
[0106] Starting from the substrate mounting/demounting unit 120,
the following units are provided in an linear alignment in the
order: a stocker 124 for preserving or temporarily storing a
substrate holder 118; a pre-wetting vessel 126 for wetting the
substrate W by immersing the substrate W within a deionized water
to enhance hydrophilicity of the surface of the substrate W; a
pre-soaking vessel 128 for removing an oxide film of a high
electrical resistance formed on a seed layer on the substrate
surface by etching with a chemical agent such as sulfuric acid or
hydrochloric acid; a first water-cleaning vessel 130a for cleaning
the substrate surface with deionized water; a blowing vessel 132
for dewatering the substrate W after cleaning; a second
water-cleaning vessel 130b; and a plating unit 134. The plating
unit 134 comprises a plurality of plating vessels 16 shown in FIGS.
1 and 2 within an overflow vessel 136, and each plating vessel 16
can contain a single substrate W for plating. In the following, a
process of plating copper is described, while other metals or
alloys such as nickel, solder, or gold can be plated in the same
manner.
[0107] A substrate holder transfer unit 140 is provided on one side
of those units for transferring substrate holders 118 together with
the substrate W held thereon. The substrate holder transfer unit
140 comprises; a first transporter 142 for transferring substrates
W between the substrate mounting/demounting unit 120 and the
stocker 124; and a second transporter 144 for transferring
substrates W between the stocker 124, pre-wetting vessel 126,
pre-soaking vessel 128, water-cleaning vessels 130a, 130b, blowing
vessel 132, and the plating unit 134. In the embodiment, the first
transporter 142 is movable as far as the water-cleaning vessel
130a, and the movable range of the second transporter 144 is
adjustable, The second transporter 144 is optional and can be
dispensed with.
[0108] On the opposite side of the substrate holder transfer unit
140 relative to the overflow vessel 136, a puddle drive unit 146 is
provided for driving puddles 34 (shown in FIGS. 1 and 2) arranged
within each plating vessel 16 for agitating the plating solution
12.
[0109] The substrate mounting/demounting unit 120 comprises a flat
mounting plate 152 laterally slidable along rails 150, which can
mount thereon two substrate holders 118 horizontally juxtaposed so
that, after one of the substrate holder 118 has transferred
substrate W to or from the substrate transfer unit 122, the
mounting plate 152 is laterally slid to allow the other substrate
holder 118 to transfer a substrate W to or from the substrate
transfer unit 122.
[0110] Next, sequential processes of bump plating using the above
plating apparatus are described. Substrates W are prepared, as
shown in FIG. 14(a), by depositing a seed layer 500 as a feeder on
the surface of the substrate W, and, after coating a resist film
502 having a thickness H of 20.about.120 .mu.m on the whole
surface, forming apertures 502a having a diameter D of 20.about.200
.mu.m. Substrates W are stored in the cassette 110 so as to face
the surface to be plated upward, and the cassette 110 is then
mounted on the cassette table 112.
[0111] Subsequently, the substrate transfer unit 122 takes one
substrate W out of the cassette 110 mounted on the table 112 and
load it on the aligner 114 to align the orientation flat or notch
to a predetermined direction. The substrate W is then transferred
to the substrate mounting/demounting unit 120 by the substrate
transfer unit 122.
[0112] At the substrate mounting/demounting unit 120, the
transporter 142 grasps two substrate holders 118 at a time with a
grasp assembly (not shown) and elevates them, transfers them to the
substrate mounting/demounting unit 120, and rotate the substrate
holder 118, 90 degrees to a horizontal state. Then, the two
substrate holders 118 are lowered and are placed concurrently on
the mounting plate 152 of the substrate mounting/demounting unit
120. At this time, a cylinder (not shown) is actuated to keep the
substrate holder 118 open.
[0113] At this state, a substrate W carried by the substrate
transfer unit 122 is inserted and the substrate holder 118 is
closed so that the substrate W is loaded. Then, the mounting plate
152 is slid laterally and the other substrate holder 118 is loaded
with the substrate W and the mounting plate 152 is returned to the
previous position.
[0114] Then, the substrate holder transfer unit 140 grasps two
substrate holders 118 at a time with the grasp assembly of the
transporter 142, and after elevating the holders 118, transfers
them to the substrate mounting/demounting unit 120 and rotate them
90 degrees to a vertical state, to thereby support them with the
stocker 124 in a suspended manner for temporary storage. In the
substrate transfer unit 122, substrate mounting/demounting unit
120, and the transporter 142 of the substrate holder transfer unit
140, the above operations are sequentially repeated to mount the
substrates W on the substrate holder 116 stored in the stocker 124
and suspend them in a certain position in the stocker 124 to
temporarily store the substrate W.
[0115] Meanwhile, the other transporter 144 of the substrate holder
transfer unit 140 grasps a pair of substrate holders 118 loaded
with a substrate W and temporarily stored in the stocker 124
concurrently with a grasping assembly (not-shown), and after
elevating them, transfers them to the pre-wetting vessel 126,
lowers them to dip into a wetting liquid such as deionized water
contained in the pre-wetting vessel 126 for wetting the surface to
enhance hydrophilicity. The wetting liquid is not limited to
deionized water as long as it can improve hydrophilicity so as to
wet the substrate surface and replace the air within fine recesses
or holes.
[0116] Then, a substrate holder 118 loaded with a substrate W is
transferred to the pre-soaking vessel 128 in the same manner as
above, so that the substrate W is dipped in the chemical agent held
in the pre-soaking vessel 128 such as sulfuric acid or hydrochloric
acid for etching a high electrical resistance oxide film on the
seed layer 500 surface to expose a clean metal surface. Further,
the holder 118 holding a substrate W is transferred to the
water-cleaning vessel 130a in the same manner as above, to clean
the substrate surface with deionized water held in the
water-cleaning vessel 130a.
[0117] After finishing water-cleaning, the substrate holder 118 is
then transferred to the plating unit 134 and is supported in the
plating vessel 16 a suspended manner. The transporter 144 of the
substrate holder transfer unit 140 operates the above steps
repeatedly to transfer the holders 118 and sequentially suspend
them in a predetermined position within the plating vessel 16. The
plating vessel 16 is readily filled with a plating solution, which
may be filled after finishing installation of the substrate holders
118.
[0118] After finishing installation of all the holders 118, voltage
is applied between the anode 14 and the substrate W as shown in
FIGS. 1 and 2, and the puddles 34 are reciprocated parallel to the
substrate surface by puddle drive unit 146, and concurrently
ejecting plating solution from the nozzles 48 provided on the
puddles 34 to plate the surface of the substrate W. The substrate
holder 118 is suspended from and secured to the upper portion of
the plating vessel 16 and electricity is fed from the plating power
source 18 to the seed layer 500 (see FIG. 14).
[0119] After finishing plating, supply of plating current and
plating solution, as well as puddle 34 reciprocation is ceased and
the substrate holders 118 loaded with a substrate W are held by the
grasp assembly of the transporter 144 two at a time and are lifted
from the plating vessel 16 and halted.
[0120] The substrate holder 118 is then transferred to the
water-cleaning vessel 130b in the same manner as above, and
immersed in the deionized water held in the water-cleaning vessel
130b to clean the surface. Then, the substrate holder 118 holding
the substrate W is transferred to the blowing vessel 132 and water
droplets on the substrate holder 118 is removed by air blow. Then,
the substrate holder 118 is returned to the stocker 124 at a
predetermined position to be suspended.
[0121] Meanwhile, the other transporter 142 of the substrate holder
transfer unit 140 holds two of the substrate holders 118 at a time,
which hold respective substrates W and have been returned to the
stocker 124 after plating, and places them on the mounting plate
152 of the substrate mounting/demounting unit 120. Then, the
substrate holder 118 on a central side is opened, and the substrate
W finished with plating is demounted by substrate transfer unit 122
and is transferred to the spin-dryer 116 to be dewatered with a
high speed rotation of the spin-dryer 116 after rinsing, and is
returned to the cassette 110 by the substrate transfer unit 122.
After returning substrate W held by one of the substrate holder 118
or simultaneously with the returning process, the mounting plate
152 is slid laterally for returning the substrate W held by the
other substrate holder 118 to the cassette 110 after rinsing and
spin-drying.
[0122] The mounting plate 152 is returned to an initial state, and
the substrate holders 118 removed of the substrate W is returned to
the stocker 124, and another pair of substrate holders 118 holding
the substrate W finished with plating are held by the transporter
142 and with a grasp assembly and are placed on the mounting plate
152 of the substrate mounting/demounting unit 120 to repeat the
same operation. When all of the substrates W finished with plating
are demounted from the substrate holder 118, spin-dried and
returned to the cassette 110, the operation is finished. Thus, the
substrate W is provided with a plated film within the openings 502a
formed on the resist film 502, as shown in FIG. 14(b).
[0123] The spin-dried substrates W are immersed into a solvent such
as acetone held at a temperature of 50.about.60.degree. C. to
remove the resist films 502 formed on the substrate W as shown in
FIG. 14(c). The substrate W is further subjected to a process for
removing the exposed seed layer 500 as shown in FIG. 14(d). Then,
the plated film is reflowed to form a bump which has been rounded
by surface tension. The substrate W is annealed at a temperature
higher than 100.degree. C. to remove residual stress within the
bump.
[0124] FIG. 15 is a plan view of another embodiment of the plating
apparatus according to the present invention for forming bumps or
the like. As shown in FIG. 15, the plating apparatus comprises: two
cassette tables 410 for loading a cassette containing substrates W
such as semiconductor wafers; an aligner 412 for aligning the
substrate W by directing an orientation flat or notch formed on the
substrate W to a certain direction; and a rinser-dryer 414 for
rinsing and drying the substrate W after plating through high speed
rotation. Further, a first transfer robot 416 is provided capable
of traveling between the two cassette tables 410, aligner 412, and
rinser-dryer 414 to transfer substrates W between them. The first
transfer robot 416 comprises a vacuum suction type hand or a
drop-in type hand to deliver substrate W in a horizontal state.
[0125] Further, this embodiment comprises four plating units 420
serially arranged. Each of these plating units 420 comprises a
plating vessel 422 and water-cleaning vessel 424 contiguously
arranged to each other, and a substrate holder 426 arranged above
these plating vessel 422 and water-cleaning vessel 424 for
detachably holding substrates W in a vertical state. The substrate
holder 426 is vertically movable by a vertical drive section 428
and laterally movable by a lateral drive section 430. In front of
the plating units 420, an aligner 412, a rinser-dryer 414, and a
second transfer robot 432 for delivering substrates W between the
substrate holder 426 of each plating unit 134 are provided. The
second transfer robot 432 comprises a hand for holding a substrate
W with a mechanical chuck and having a reversing assembly 434 for
tilting a substrate W between a horizontal state and a vertical
state, so that it holds substrates W in a horizontal state when
delivering between the aligner 412 and rinser-dryer 414, and in a
vertical state between the substrate holder 426.
[0126] Within each plating vessel 422, an anode 436 is provided at
a predetermined position to confront the substrate W held by the
substrate holder 426. Each plating vessel 422 further comprises
puddles 440 arranged between the substrate W and anode 436 to
reciprocatingly move parallel to the substrate W to equalize the
plating solution flow, and a regulation plate 442 having a central
aperture of a size corresponding to the substrate W for lowering
potentials about the periphery of the substrate W to equalize
thickness of the plated film on the substrate W. On either one of
the puddle 440 or regulation plate 442, a nozzle as shown in FIGS.
1, 2 and 5 is provided to eject plating solution toward the
substrate W held by the substrate holder 426.
[0127] Here, sequential processes for plating the substrate W to
form bumps by using the plating apparatus constructed as above will
be described. Substrates W are prepared, as shown in FIG. 14(a), by
depositing a seed layer 500 as a feeder on the surface of the
substrate W, and, after coating a resist film 502 having a
thickness H of 20.about.120 .mu.m on the whole surface, forming
apertures having a diameter D of 20.about.200 .mu.m. Substrates W
are stored in the cassette so as to face the surface to be plated
upward, and the cassette is then mounted on the cassette table
410.
[0128] Subsequently, the first transfer robot 416 takes one
substrate W out of the cassette mounted on the table 410 and put it
on the aligner 412 to align the orientation flat or notch to a
predetermined direction. The aligned substrate W is then tilted in
the reversing assembly 434 from a horizontal state to a vertical
state, and is delivered to the substrate holder 426 of one of the
plating units 420.
[0129] In this embodiment, transfer of the substrate W is performed
at a region above the water-cleaning vessel 424. Substrate holder
426 is elevated by the vertical drive section 428, and positioned
beside the water-cleaning vessel 424 by lateral drive section 430
to receive the substrate W from the second transfer robot 432 in a
vertical state.
[0130] Then, the substrate holder 426 is moved to the plating
vessel 422 by the lateral drive section 430. The plating vessel 422
is readily filled with a plating solution. The substrate holder 426
is lowered by the vertical drive section 428 and the substrate W
held by the substrate holder 426 is immersed into the plating
solution within the plating vessel 422. By applying plating voltage
between the anode 436 and the substrate W, moving the puddles 440
reciprocatingly parallel to the substrate surface, and concurrently
ejecting the plating solution from the nozzles 48 provided on at
least one of the puddles 440 or regulation plate 442, the surface
of the substrate W is plated.
[0131] When plating is finished, application of voltage, supply of
plating solution and reciprocation of the puddle 440 are ceased,
and the substrate holder 426 holding the substrate W is elevated
and withdrawn from the plating vessel 422.
[0132] The substrate holder 426 is transferred to the
water-cleaning vessel 424 by the lateral drive assembly 430, and
lowered into the water-cleaning vessel 424 to be washed by
deionized water. The washing process is performed by ejecting
deionized water toward the substrate W from nozzle (not shown)
arranged within the water-cleaning vessel 424 while lifting the
substrate W upward within the vessel 424. Another possible washing
process is to rapidly pull up the substrate holder 426 through a
deionized water which is readily supplied to the water-cleaning
vessel 424 in advance. It is naturally possible to combine both
processes.
[0133] The second transfer robot 432 receives the washed substrate
W from the substrate holder 426 in a vertical state at a region
above the water-cleaning vessel 424, rotates it 90 degrees to a
horizontal position, and transfers it to the rinser-dryer 414 for
loading there. After rinsing and dewatering by high speed rotation
of the rinser-dryer 414, the substrate W is returned to the
cassette loaded on the cassette table 410 to finish operation.
Thus, the substrate W is provided with a plated film 504 within the
openings 502a formed on resist films 502, as shown in FIG.
14(b).
[0134] Now, another embodiment of the present invention will be
described by referring to the attached drawings.
[0135] As shown in FIG. 16, the plating apparatus comprises: one or
plural cassette tables 610 for loading a cassette containing
substrates W such as semiconductor wafers; an aligner 612 for
aligning the substrate W by directing an orientation flat or notch
formed on the substrate W to a certain direction; and a
rinser-dryer 614 for rinsing and drying the substrate W through
high speed rotation after plating. Further, a first transfer robot
616 is provided between the one or plural cassette tables 610,
aligner 612, and rinser-dryer 614 which is capable of traveling and
transferring substrates W between these units. The first transfer
robot 616 comprises a vacuum suction type hand or a drop-in type
hand to deliver substrate W in a horizontal state.
[0136] Further, the plating apparatus comprises four plating units
620 serially arranged. The number or arrangement of these plating
units 620 can be optionally selected. In front of these plating
units 620, an aligner 612, a rinser-dryer 614, and a second
transfer robot 632 for delivering substrates W between the
substrate holder 634 of each plating unit 620 are provided. The
second transfer robot 632 comprises a hand 626 for holding a
substrate W by a mechanical chuck and having a reversing assembly
624 for tilting a substrate W between a horizontal state and a
vertical state, so that it holds substrates W in a horizontal state
when delivering to the aligner 612 and rinser-dryer 614, and in a
vertical state to the substrate holder 634.
[0137] As shown in FIGS. 17 to 23, each plating unit 620 comprises
a plating vessel 632 mounted on a pedestal 630 and a substrate
holder 634 arranged in a confronting position to the plating vessel
632. The substrate holder 634 is fixed on an upper surface of a
slide plate 638 laterally slidable along rails 636 via a bracket
640.
[0138] The plating vessel 632 comprises: a vessel body 642 shaped
as a box opening upward and having a plating solution inlet port
642a, a plating solution inlet/drain port 642b, and a front
aperture 642c formed on a front surface facing the substrate holder
634; and an overflow vessel 643 as shown in FIG. 21 provided on the
upper portion of the vessel body 642. The vessel body 642 is
partitioned by a partition plate 644 having a plating solution
flow-in port 644a and a plating solution flow-through port 644b.
Within the vessel body 642 and above the plating solution flow-in
port 644a, an anode 636 is vertically arranged by being held by an
anode support 648. A weir member 652 having a rectangular box shape
and opening in both upward and downward directions is provided
vertically movable and to surround the anode 636 when it is
lowered. A seal member 650 is attached to the lower edge of the
weir member 652.
[0139] The seal member 650 pressingly contacts the upper surface of
the partition plate 644 when the weir member 652 is lowered to
define an enclosed reservoir chamber 654 within the vessel body
642. This reservoir chamber 654 is used to reserve plating solution
even when the apparatus is not plating, and the anode 636 is
immersed in the reserved plating solution within the reservoir
chamber 654 to prevent it from drying. This prevents a black film
deposited on the surface of the anode 636 from drying, being
oxidized, peeling off and sticking to the plating surface of the
substrate W. The weir member 652 is lifted up when the apparatus is
in operation to open the front face of the anode 636.
[0140] A regulation plate 656 having a central aperture 656a of a
size conforming to the size of the substrate W is arranged between
the weir member 652 and the front aperture 642c of the vessel body
642 for lowering the potentials at the periphery of the substrate
surface held by the holder 634 to provide more uniform film
thickness distribution. Nozzles 662 are provided on the surface of
the regulation plate 656 at locations proximate to the central
aperture and along a circumferential direction, for example, for
ejecting plating solution toward the center of the substrate W held
by the holder 634.
[0141] Puddles 640 are arranged between the weir member 652 and
aperture 642c of the vessel body 642 to reciprocatingly move
parallel to the substrate W held by the substrate holder 634 by
being driven by the puddle drive motor to thereby control (or
disturb) the plating solution flow between the regulation plate 656
and the substrate W held by the substrate holder 634.
[0142] Further, a nozzle head 664 is provided within the vessel
body 642 and in front of the aperture 642c, which extends
vertically and comprises nozzles 662 at a predetermined pitch along
the longitudinal direction. The nozzle head 664 is reciprocatingly
movable parallel to the aperture 642c by a nozzle head drive motor.
The nozzle head 664 is retracted at a standby position beside the
substrate holder 634 while plating is operated to avoid
interference with the fore and aft movement of the substrate holder
634, and when the plating is finished, moves forward ahead of the
substrate holder 634 to move reciprocatingly and parallel to the
plating surface of the substrate W while ejecting cleaning liquid
such as deionized water, for example, and inert gas such as
N.sub.2. Thus, the substrate W is showered by the ejected deionized
water and inert gas and is washed away of plating solution
remaining on the surfaces of the substrate W and substrate holder
634, and finally, the remaining deionized water is removed from the
surface by being blown away by the inert gas.
[0143] As shown in FIG. 22 in detail, an intermediate plate 666 and
a surface plate 669 are laminated or built-up at the periphery of
the aperture 642c of the vessel body 642. The intermediate plate
666 comprises an annular communication groove 666a, which
communicates with a vacuum source (not shown), and the surface
plate 669 comprises a suction port 668a communicating with the
communication groove 666a and attached with an annular seal plate
668.
[0144] The plating vessel 632 is provided with a plating solution
regulation and supply system as shown in FIG. 21. The plating
solution regulation and supply system comprises: a plating solution
supply tank 670; a plating solution supply system 672 and an
auxiliary plating solution supply system 674 for supplying and
circulating the plating solution within the plating solution supply
tank 670 to the plating vessel 632; a plating solution regulation
system 676 for circulating the plating solution within the plating
solution supply tank 670 for regulation of a plating bath by
controlling the temperature or removing impurities.
[0145] The plating solution supply system 672 comprises: a main
supply line 678 extending from the plating solution supply tank 670
and connected to the plating solution inlet port 642a of the vessel
body 642; and a return line 680 communicating the overflow vessel
643 and plating solution supply tank 670. The main supply line 678
comprises a feeder pump 682, a filter 684, a first flow controller
688a, a shutter valve 686a, and a second flow controller 686b. A
branch line 690 is provided to bifurcate from the main supply line
678 at an upstream of the shutter valve 686a and communicates to
plating solution nozzles 659 arranged on the inside of the
regulation plate 656 through a shutter valve 686b and a flow
controller 668c. The plating solution supply system 672 further
comprises: a rapid supply line 692 connected to the main supply
line 678, comprising a shutter valve 686c, and connected to the
plating solution inlet/drain port 642b of the vessel body 642; and
a rapid drain line 694 directly connecting the plating solution
inlet/drain port 642b of the vessel body 642 and the plating
solution supply tank 670 and comprising a shutter valve 686d.
[0146] The auxiliary plating solution supply system 674 comprises
an auxiliary supply line 696 bifurcating from the main supply line
678 at an upstream of the shutter valve 686a and communicates to
the plating solution flow-in port 644a of the partition plate 644
through a shutter valve 686e, so that the rapid drain line 694
works dual-purposely as a return line 696.
[0147] The plating solution regulation system 676 comprises a
circulation line having a circulation pump 700, a heat-exchanger
702, and a filter 704. Thus, the plating solution within the
plating solution supply tank 670 is filtered by passing through the
filter 704 as the circulation pump 700 is operated.
[0148] The substrate holder 634 is constructed to move back and
forth along a rail 712 in accordance with the activation of a
pushing cylinder 710 arranged between the slide plate 638 and the
bracket 640. The substrate holder 634 comprises: a disc-shaped
supporting head 714 of approximately the same size with the
substrate W to be plated; and a seal unit 716 arranged in front of
the supporting head 714 on a side facing the plating vessel 632,
and detachably attached to the opening end of a casing 718 which
surrounds the supporting head 714.
[0149] The supporting head 714 is connected to a piston rod 721 of
a horizontally arranged cross drive cylinder 720 which is fixed to
the casing 718, and comprises one or more guiding rods 722
connected thereto at positions along a circumferential line. These
guiding rods 722 are supported by a slide bearing 724 provided on
the casing 718 so as to be movable in a cross direction to the
supporting head 714. Thus, the supporting head 714 is moved back
and forth while being guided by the guiding rods 722.
[0150] One side of the supporting head 714 facing the plating
vessel 632 comprises a flat surface 714a which is formed with a
recess 714b for receiving a hand 626 of the transfer robot 622,
which extends horizontally and employs vacuum chucking for holding
a substrate W for example. A plurality of holder pins 728 are
arranged at locations to surround the periphery of the supporting
head 714, whose tip ends protrude from the flat surface 714a toward
the plating vessel 632 and horizontally extend rearward. The inner
surface of the holder pin 728 protruding from the flat surface 714a
is provided with a recess 714b for receiving the outer peripheral
edge of the substrate W so as to temporarily position the substrate
W while preventing displacement. The proximal end of the holder pin
728 is connected to a temporary positioning cylinder 730 provided
on the rear surface of the supporting head 714, so that the
temporary positioning cylinder 730 drives the holder pin 728 to
move along a radial direction of the supporting head 714.
[0151] Thus, the transfer robot 622 holds the substrate W with the
vacuum chucking type hand 626 and transfers it to the front surface
of the supporting head 714. Then, the robot moves the hand 626
toward the supporting head 714 and locates it within the recess
714b close to the flat surface 714. The holder pins 728 are moved
radially inside the supporting head 714 so that the peripheral edge
of the substrate W is received in the recess 714b. The hand 626 is
extracted so that the substrate W is held in front of the
supporting head 714 by the holder pins 728.
[0152] The seal unit 716 comprises a generally cylindrical support
member 732, which can be attached or detached to the opening of the
casing 718 by using, for example, a cramp type fastener 734 (shown
in FIG. 19) with a single manipulative action. As is described
below, by using the seal unit 716, in which a seal ring 740, a
cathode 762, and, additionally, a seal member 736 are integrally
incorporated, expendable items such as seal ring 740 or seal member
736 can be easily and rapidly exchanged together with the cathode
762. Instead of using the cramp type fastener 734, the seal unit
716 can be attached/detached by using a plunger for example, to
exchange the seal ring 740 or seal member 736 more easily.
[0153] The annular seal member 736 is provided on the front surface
of the support member 732 facing the plating vessel 632, and at a
position opposite to the seal plate 668 provided on the surface
plate 669. The seal member 736 is formed with a pair of projections
736a, 736b at the inner and outer edges. When the supporting head
714 moves toward the plating vessel 632, these projections 736a,
736b abut with the seal plate 668 so that the space defined by the
projections 736a, 736b communicates with the suction port 668a.
Thus, by vacuuming the space through the suction port 668a, the
aperture 642c of the vessel body 642 is water-tightly sealed so as
to block the aperture 642c with the substrate holder 634.
[0154] The support member 732 of the seal unit 716 comprises a
cylindrical portion of a size through which the supporting head 714
holding the substrate W can pass, and on which the annular seal
ring 740 and cathode electrodes 742 are integrally attached. That
is, the seal ring 740 is pressed against the periphery of the
substrate W, which is temporarily held by the supporting head 714,
so as to seal the region. The seal ring 740 is fixed by being
supported from both sides of the outer periphery with the front
surface of the support member 732 facing the plating vessel 632 and
a stopper ring so as to project inside the cylindrical portion. The
inner edge of the seal ring 740 is formed to cuspidally project
toward the supporting head 714. On the other hand, the cathode
electrodes 742 are elastically pressed against the periphery of the
substrate W which is temporarily held by the supporting head 714,
thereby allowing to feed electricity to the seed layer 500 formed
on the surface of the substrate W. The cathode electrodes 742 are
located at circumferentially spaced positions at a predetermined
pitch, and the edge facing the plating vessel 632 is circularly
curved toward the inside of the support member 732, and the curved
portions are covered by the seal ring 740.
[0155] With such arrangement, when the supporting head 714
temporarily holding the substrate W moves toward the plating vessel
632, the seed layer 800 formed on the surface of the substrate W
contacts with the cathode electrodes 742 at the periphery of the
substrate W, and further progress of the supporting head 714 makes
the cathode electrodes 742 bend to secure the contact as well as
the periphery of the substrate W be pressed toward the seal ring
740 to provide a water-tight seal. At this time, the substrate W is
in close contact with the flat surface 714a of the supporting head
714 to be fixed thereto. The cathode electrodes 742 are located
outside the seal formed by the seal ring 740 so as to prevent the
cathode electrodes 742 from contacting the plating solution.
[0156] Next, a series of operations are explained in which the
substrate holder 634 holds the substrate W and the substrate holder
634 then water-tightly seals the aperture 642c of the vessel body
642 of the plating vessel 632 for plating the substrate W by
referring to FIGS. 24 to 26.
[0157] As shown in FIG. 24(a), the supporting head 714 of the
substrate holder 634 is retracted away from the plating vessel 632,
and the substrate W is transferred between the substrate holder 634
and the seal unit 716, which is held by the hand 626 of the
transfer robot 622 (shown in FIG. 16) through suction force or by
mechanical chucking and vertically arranged after reversing.
Subsequently, the hand 626 holding the substrate W with a vacuum
suction force, for example, is transferred to the supporting head
714 and brought into the recess 714b of the supporting head 714 to
make the substrate W approach to the flat surface 714a of the
supporting head 714, as shown in FIG. 24(b). Then, the holder pins
728 are radially moved toward inside the supporting head 714, and
the peripheral edge of the substrate W is located within the recess
714b to temporarily hold the substrate W. FIG. 17 shows this state.
Then, the hand 626 releases the substrate W and is retracted from
the substrate holder 634. After that, the cross drive cylinder 720
is actuated to move the supporting head 714 toward the plating
vessel 632.
[0158] As the supporting head 714 moves forward, as shown in FIG.
24(d), the seed layer 800, as shown in FIG. 27, formed on the
substrate W is contacted by the cathode electrode 742 at the
periphery of the substrate W. As the supporting head 714 further
moves forward, the periphery of the substrate W is pressed against
the seal ring 740 to provide a water-tight seal and, concurrently,
is secured through a close contact with the flat surface 714a of
the supporting head 714.
[0159] In the plating vessel 632, as shown in FIG. 25(a), the weir
member 652 is lowered so as to press the seal member 650 at the
lower edge against the upper surface of the partition plate 644, to
thereby define a reservoir chamber 654 with the weir member 652.
Plating solution is introduced through the plating solution
auxiliary supply system 674 to the reservoir chamber 654 and
immerses the anode 636 in the plating solution within the reservoir
chamber 654 before starting plating. This process prevents the
anode 636 and the a black film deposited on the surface of the
anode 636 from drying, being oxidized, peeling off and sticking to
the plating surface of the substrate W.
[0160] At the same time, the plating solution introduced to the
reservoir chamber 654 and having overflowed the weir member 652 is
returned to the plating solution supply tank 670 through the return
line 698 so as to circulate the plating solution within the
reservoir chamber 654 even when the apparatus is not in operation.
By doing so, the plating solution within the reservoir chamber 654
does not suffer from variation of composition or deterioration.
[0161] To start plating, the pushing cylinder 710 is actuated to
move the substrate holder 634 toward the plating vessel 632 as
shown in FIG. 24(e), and when the projections 736a, 736b abut with
the seal plate 668 (cell body 642) provided on the surface plate
669, the space defined by the projections 736a, 736b are vacuumed
to provide a water-tight seal to the aperture 642c of the vessel
body 642 to block there. At this state, the substrate holder 634 is
continuously pressed at a constant pressure against the vessel body
642 with the pushing cylinder 710. The state of the plating vessel
632 is shown in FIG. 25(b).
[0162] Then, the plating solution is rapidly supplied into the
vessel body 642 through the rapid supply line 692 of the plating
solution supply system 672 as shown in FIG. 25(c). When a certain
amount of the plating solution is introduced to the vessel body
642, the weir member 652 is lifted as shown in FIG. 25(d), and the
anode 636 is confronted by the surface of the substrate W held in
the substrate holder 634. Here, the plating power source applies
plating voltage between the anode 636 and the cathode 762 which
conducts to the seed layer 800 (see FIG. 27), and the predetermined
amount of plating solution is supplied to the interior of the
vessel body 642, through the plating solution supply system 672.
Meanwhile, as shown in FIG. 26(a), plating solution is supplied to
the nozzles 662 provided on the regulation plate 656 through the
branch line 690 so as to eject the plating solution toward the
substrate W held by the substrate holder 634, and the puddles 660
(see FIG. 21) are reciprocatingly moved parallel to the substrate
surface. The plating solution having overflowed to the overflow
vessel 643 is returned to the plating solution supply tank 670
through the return line 680 for circulation to thereby plate the
substrate surface. The state here is shown in FIG. 18.
[0163] When the plating is finished, the application of the plating
voltage is stopped, and the supply of the plating solution is
ceased and the weir member 652 is lowered as shown in FIG. 26(b),
and the plating solution is introduced into the reservoir chamber
654 confined by the weir member 652 through the auxiliary supply
system.
[0164] Then, the plating solution within the vessel body 642 except
within the reservoir chamber 654 is rapidly drained through the
rapid drain line 694 by opening the shutter valve 686d, as shown in
FIG. 26(c). This rapid drainage decreases waiting time necessary
for transition to a following plating process.
[0165] Then, the pushing cylinder 710 is reversely actuated to move
the substrate holder 634 away from the plating vessel 632, and the
nozzle head 664 is moved from the retracted position and parallel
to the surface of the substrate W held by the substrate holder 634,
and cleaning liquid such as deionized water is ejected from the
nozzles 662 toward the substrate surface to rinse off the plating
solution remaining on the substrate W. The deionized water is
removed by blowing inert gas such as N.sub.2 gas. Then, the plated
substrate W is delivered to the hand 626 of the transfer robot 622
by reversely performing the processes described above.
[0166] FIGS. 19 and 20 show a state where the substrate holder 634
is subjected to maintenance. During maintenance, the substrate
holder 634 is slid together with the slide plate 638 along the rail
712 to a lateral position of the plating vessel 632, so that the
space necessary for the maintenance is reserved to facilitate
operations such as exchanging the seal unit 716 or maintaining the
substrate holder 634.
[0167] Next, sequential processes of bump plating using the above
plating apparatus are described. Substrates W are prepared, as
shown in FIG. 27(a), by depositing a seed layer 800 as a feeder on
the surface of the substrate W, and, after coating a resist film
802 having a thickness H of 20.about.120 .mu.m on the whole
surface, forming apertures having a diameter D of 20.about.200
.mu.m. Substrates W are stored in the cassette so as to face the
surface to be plated upward, and the cassette is then mounted on
the cassette table 610.
[0168] Subsequently, the first transfer robot 616 takes one
substrate W out of the cassette mounted on the table 610 and put it
on the aligner 612 to align the orientation flat or notch to a
predetermined direction. The second transfer robot 622 takes the
aligned substrate W from the aligner 612 and tilts the substrate W
90 degrees from a horizontal position to a vertical position with
the reversing assembly 624 and delivers the substrate W to a
substrate holder 634 of one of the plating units 620. Then, the
substrate W held by the substrate holder 634 is plated, washed by
deionized water, and air-blown, and is delivered to the second
transfer robot 622. The second transfer robot 622 tilts the
substrate W 90 degrees from a vertical position to a horizontal
position and transfers the substrate W to the rinser-dryer 614 to
place it.
[0169] The rinser-dryer 614 rinses and dewaters the substrate W and
returns it to the cassette loaded on the table 610 to finish the
operation. Thus, the substrate W is formed with a deposited film
804 developed within the aperture 802a of the resist film 802, as
shown in FIG. 27(b).
[0170] The spin-dried substrates W are immersed into a solvent such
as acetone held at a temperature of 50.about.60.degree. C. to
remove resist films 802 formed on the substrate W as shown in FIG.
27(c). The substrate W is further subjected to a process for
removing the exposed and unnecessary seed layer 800 as shown in
FIG. 27(d). Then, the plated film 804 is reflowed to form a bump
806 which has been rounded by surface tension, as shown in FIG.
27(e). The substrate W is annealed at a temperature higher than
100.degree. C. to remove residual stress within the bump 806.
* * * * *