U.S. patent application number 10/387935 was filed with the patent office on 2003-09-11 for segmenting of processing system into wet and dry areas.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Denome, Mark, Hey, H. Peter W., Sugarman, Michael N..
Application Number | 20030168346 10/387935 |
Document ID | / |
Family ID | 24640819 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030168346 |
Kind Code |
A1 |
Hey, H. Peter W. ; et
al. |
September 11, 2003 |
Segmenting of processing system into wet and dry areas
Abstract
An electroplating system that includes a wet area comprising one
or more electrochemical processing cells for processing one or more
semiconductor substrates in an electrolyte solution, a dry area for
transferring the semiconductor substrates to the wet area prior to
processing the semiconductor substrates and for receiving the
semiconductor substrates from the wet area after processing the
semiconductor substrates, and a cleaning module for removing
unwanted deposits from the semiconductor substrates after
processing the semiconductor substrates in the wet area but prior
to transferring the semiconductor substrates to the dry area.
Inventors: |
Hey, H. Peter W.;
(Sunnyvale, CA) ; Sugarman, Michael N.; (San
Francisco, CA) ; Denome, Mark; (San Jose,
CA) |
Correspondence
Address: |
Patent Counsel
APPLIED MATERIALS, INC.
P.O. Box 450A
Santa Clara
CA
95052
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
24640819 |
Appl. No.: |
10/387935 |
Filed: |
March 13, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10387935 |
Mar 13, 2003 |
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09658336 |
Sep 8, 2000 |
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6551488 |
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09658336 |
Sep 8, 2000 |
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09289074 |
Apr 8, 1999 |
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6258220 |
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Current U.S.
Class: |
205/157 ;
257/E21.175 |
Current CPC
Class: |
C25D 17/001 20130101;
H01L 21/6708 20130101; H01L 21/67126 20130101; H01L 21/6723
20130101; C25D 7/123 20130101; C25D 5/48 20130101; H01L 21/67051
20130101; H01L 21/67028 20130101; H01L 21/2885 20130101; H05K 3/241
20130101 |
Class at
Publication: |
205/157 |
International
Class: |
C25D 007/12 |
Claims
What is claimed is:
1. A method of processing a semiconductor substrate in a processing
system segmented into a wet area and a dry area, the method
comprising: introducing the semiconductor substrate into the dry
area of the processing system; moving the semiconductor substrate
into the wet area of the processing system; processing the
semiconductor substrate in an electrochemical processing cell; and
removing unwanted deposits disposed on the semiconductor substrate
during processing.
2. The method of claim 1, further comprising transferring the
semiconductor substrate to the dry area of the processing system
after removing the unwanted deposits disposed on the semiconductor
substrate.
3. The method of claim 1, wherein removing the unwanted deposits
comprises rinsing and drying the semiconductor substrate.
4. The method of claim 1, wherein removing the unwanted deposits
comprises spinning and rinsing the semiconductor substrate.
5. The method of claim 1, wherein removing the unwanted deposits
comprises spinning, rinsing and drying the semiconductor
substrate.
6. The method of claim 1, wherein removing the unwanted deposits
comprises rinsing and drying the semiconductor substrate in a
cleaning module disposed between the wet area and the dry area.
7. The method of claim 1, wherein removing the unwanted deposits
comprises: rinsing the semiconductor substrate with de-ionized
water.
8. The method of claim 1, wherein removing the unwanted deposits
comprises: rinsing the semiconductor substrate with at least one of
an etchant, de-ionized water and alcohol.
9. The method of claim 1, wherein removing the unwanted deposits
comprises: spinning the semiconductor substrate at a high angular
velocity; and rinsing the semiconductor substrate with at least one
of an etchant and de-ionized water.
10. The method of claim 1, wherein removing the unwanted deposits
comprises: spinning the semiconductor substrate at a high angular
velocity; delivering one of a rinsing fluid and de-ionized water
onto a top surface of the semiconductor substrate; and delivering
one of an etchant and acid onto a bottom side of the semiconductor
substrate.
11. The method of claim 10, wherein the one of the rinsing fluid
and de-ionized water is delivered at a greater rate than the one of
the etchant and the acid.
12. The method of claim 1, wherein removing the unwanted deposits
comprises: spinning the semiconductor substrate at a high angular
velocity; applying an etchant to the unwanted deposits disposed on
the semiconductor substrate; applying de-ionized water to the
semiconductor substrate to remove the etchant and the unwanted
deposits from the semiconductor substrate; and continuing to spin
the semiconductor substrate to dry the semiconductor substrate.
13. The method of claim 1, wherein removing the unwanted deposits
comprises removing the unwanted deposits from one or more beveled
edges of the semiconductor substrate.
14. The method of claim 1, wherein removing the unwanted deposits
comprises: spinning the semiconductor substrate at a high angular
velocity; and rinsing one or more beveled edges of the
semiconductor substrate with at least one of an etchant and
de-ionized water.
15. The method of claim 1, wherein removing the unwanted deposits
comprises: spinning the semiconductor substrate at a high angular
velocity; and delivering at least one of an etchant and de-ionized
water to a peripheral edge of the semiconductor substrate.
16. The method of claim 1, wherein removing the unwanted deposits
comprises: spinning the semiconductor substrate at a high angular
velocity; delivering an etchant to a peripheral edge of the
semiconductor substrate; and delivering de-ionized water to the
peripheral edge of the semiconductor substrate after delivering the
etchant to the peripheral edge.
17. The method of claim 1, wherein removing the unwanted deposits
comprises removing the unwanted deposits disposed along an edge of
the semiconductor substrate to create an edge exclusion zone.
18. The method of claim 1, wherein processing the semiconductor
substrate comprises exposing the semiconductor substrate to an
electrolyte solution contained in the electrochemical processing
cell.
19. The method of claim 1, further comprising annealing the
semiconductor substrate in a thermal anneal chamber after removing
the unwanted deposits.
20. An electroplating system, comprising: a wet area comprising one
or more electrochemical processing cells for processing one or more
semiconductor substrates in an electrolyte solution; a dry area for
transferring the semiconductor substrates to the wet area prior to
processing the semiconductor substrates and for receiving the
semiconductor substrates from the wet area after processing the
semiconductor substrates; and a cleaning module for removing
unwanted deposits from the semiconductor substrates after
processing the semiconductor substrates in the wet area but prior
to transferring the semiconductor substrates to the dry area.
21. The system of claim 20, wherein the cleaning module is disposed
between the dry area and the wet area.
22. The system of claim 20, wherein the cleaning module comprises:
a housing; a rotatable pedestal disposed in the housing; and a
first plurality of nozzles disposed around the housing for
delivering rinsing fluid to the surfaces of the semiconductor
substrates.
23. The system of claim 22, wherein the cleaning module further
comprises: a second plurality of nozzles disposed around the
housing for delivering fluid to one or more beveled edges of the
semiconductor substrates.
24. The system of claim 20, wherein the dry area comprises a
thermal chamber configured to anneal the semiconductor substrates
after the unwanted deposits are removed from the semiconductor
substrates.
25. The system of claim 24, wherein the thermal chamber comprises:
a heating plate positioned inside the chamber; a cooling plate
positioned inside the chamber; a gas inlet disposed through the
chamber to supply gases into the chamber; and a gas outlet disposed
at a lower portion of the chamber to exhaust the gases out of the
chamber.
26. The system of claim 24, wherein the thermal anneal chamber
further comprises a plurality of pins disposed through the heating
plate configured to support the semiconductor substrates.
27. The system of claim 24, wherein the heating plate is configured
to heat a lower surface of the semiconductor substrate.
28. The system of claim 24, wherein the cooling plate is configured
to cool an upper surface of the semiconductor substrate.
29. The system of claim 20, wherein the dry area further comprises
a dry robot for transferring the semiconductor substrates within
the dry area and for transferring the semiconductor substrates
between the dry area and the wet area.
30. The system of claim 20, wherein the wet area further comprises
a wet robot for transferring the semiconductor substrates within
the wet area and for transferring the semiconductor substrates
between the wet area and the dry area.
31. The system of claim 20, wherein the dry area further comprises
a dry robot for transferring the semiconductor substrates within
the dry area and for transferring the semiconductor substrates
between the dry area and the wet area; and wherein the wet area
further comprises a wet robot for transferring the semiconductor
substrates within the wet area and for transferring the
semiconductor substrates between the wet area and the dry area.
32. An electroplating system, comprising: a wet area comprising one
or more electrochemical processing cells for processing one or more
substrates in an electrolyte solution; a dry area for transferring
the substrates to the wet area prior to processing the substrates
and for receiving the substrates from the wet area after processing
the substrates; a cleaning module disposed between the dry area and
the wet area, wherein the cleaning module is configured to remove
unwanted deposits from the substrates after processing the
substrates in the wet area but prior to transferring the substrates
to the dry area, and wherein the cleaning module comprises a first
plurality of nozzles configured to remove the unwanted deposits
from the surfaces of the substrates and a second plurality of
nozzles configured to remove the unwanted deposits from the beveled
edges of the substrates; wherein the dry area comprises: a thermal
chamber configured to anneal the substrates after the unwanted
deposits are removed from the substrates; and a dry robot for
transferring the substrates within the dry area and for
transferring the substrates between the dry area and the wet area;
and wherein the wet area further comprises a wet robot for
transferring the substrates within the wet area and for
transferring the substrates between the wet area and the dry
area.
33. An electroplating system, comprising: a wet area comprising one
or more electrochemical processing cells for processing one or more
substrates in an electrolyte solution; a dry area for transferring
the substrates to the wet area prior to processing the substrates
and for receiving the substrates from the wet area after processing
the substrates; and a cleaning module disposed between the dry area
and the wet area, wherein the cleaning module is configured to
remove unwanted deposits from the substrates after processing the
substrates in the wet area but prior to transferring the substrates
to the dry area, and wherein the cleaning module comprises: a
housing; a rotatable pedestal disposed in the housing; and a
plurality of nozzles disposed around the housing for delivering
rinsing fluid to the substrates.
34. An electroplating system, comprising: a wet area comprising one
or more electrochemical processing cells for processing one or more
substrates in an electrolyte solution; and a dry area for
transferring the substrates to the wet area prior to processing the
substrates and for receiving the substrates from the wet area after
processing the substrates, wherein the dry area comprises a thermal
anneal chamber for annealing the substrates after processing the
substrates in the wet area.
35. The system,of claim 34, further comprising a cleaning module
disposed in a substrate pathway between the one or more
electrochemical processing cells and the thermal anneal
chamber.
36. The system of claim 35, further comprising one or more robots
configured to transfer the substrates along the substrate
pathway.
37. The system of claim 35, wherein the cleaning module comprises:
a housing; a rotatable pedestal disposed in the housing; and a
first plurality of nozzles disposed around the housing for
delivering rinsing fluid to the substrates.
38. The system of claim 37, wherein the cleaning module further
comprises a second plurality of nozzles disposed around the housing
for delivering fluid to one or more beveled edges of the
substrates.
39. The system of claim 34, further comprising one or more robots
for transferring the substrates within the wet area, within the dry
area and between the wet area and dry area.
40. The system of claim 34, wherein the wet area comprises a wet
robot for transferring the substrates within the wet area and for
transferring the substrates between the wet area and the dry
area.
41. The system of claim 34, wherein the dry area further comprises
a dry robot for transferring the substrates within the dry area and
for transferring the substrates between the dry area and the wet
area.
42. The system of claim 34, wherein the wet area comprises a wet
robot for transferring the substrates within the wet area and for
transferring the substrates between the wet area and the dry area;
and wherein the dry area further comprises a dry robot for
transferring the substrates within the dry area and for
transferring the substrates between the dry area and the wet
area.
43. The system of claim 34, wherein the thermal chamber comprises:
a heating plate positioned inside the chamber; a cooling plate
positioned inside the chamber; a gas inlet disposed through the
chamber to supply gases into the chamber; and a gas outlet disposed
at a lower portion of the chamber to exhaust the gases out of the
chamber.
44. An electroplating system, comprising: a wet area comprising one
or more electrochemical processing cells for processing one or more
substrates in an electrolyte solution; a dry area for transferring
the substrates to the wet area prior to processing the substrates
and for receiving the substrates from the wet area after processing
the substrates, wherein the dry area comprises a thermal anneal
chamber for annealing the substrates after processing the
substrates in the wet area; a cleaning module disposed in a
substrate pathway between the one or more electrochemical
processing cells and the thermal anneal chamber; and one or more
robots for transferring the substrates within the wet area, within
the dry area and between the wet area and dry area.
Description
CONTINUATION INFORMATION
[0001] This is a continuation of prior filed U.S. patent
application Ser. No. 09/658,336, filed Sep. 8, 2000 and entitled
"SEGMENTING OF PROCESSING SYSTEM INTO WET AND DRY AREAS," which is
a continuation-in-part of prior filed U.S. patent application Ser.
No. 09/289,074, filed Apr. 8, 1999, and entitled "ELECTRO-CHEMICAL
DEPOSITION SYSTEM."
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to electroplating of
a metal film on a substrate. More particularly, the present
invention relates to containing a processing fluid to selected
areas within an electroplating system.
[0004] 2. Background of the Related Art
[0005] A variety of processes are performed on semiconductor
substrates, such as semiconductor wafers, LCD displays, etc. During
such processing, it is desired to keep the substrate as clean as
possible. There are a variety of wet processes, such as
electroplating, in which the substrate is immersed in a fluid such
as electrolyte solution. During electroplating, it becomes
especially challenging to keep the substrate clean since the
processing involves the immersion of the substrate into electrolyte
solution. Electroplating is performed by applying a prescribed
voltage across an electrolyte solution between the seed layer on
the substrate and an anode. Electroplating deposits metal ions
contained within the electrolyte solution on the layer to form the
deposited metal film. Electroplating is a wet process in which a
fluid electrolyte solution suspends, and transports, metal ions,
such as copper sulfate. A metal film is deposited on the seed layer
when sufficient negative voltage, known as plating voltage, is
applied between the seed layer and the anode. Immersing the
substrate into a liquid such as electrolyte solution makes keeping
the substrate clean from impurities very difficult.
[0006] The use of electroplating in integrated circuit design
originated with the fabrication of lines on circuit boards.
Electroplating is now used to deposit metals, such as copper, on
substrates to form features, such as vias, trenches, or contacts.
One embodiment of feature filling technique that includes
electroplating requires initially depositing a diffusion barrier
layer on the substrate using physical vapor deposition (PVD) or
chemical vapor deposition (CVD). A seed layer is then deposited on
the diffusion barrier layer using PVD or CVD to define a plating
surface. A metal film is deposited on the seed layer on the
substrate by electroplating. Finally, the deposited metal film can
be planarized by another process, e.g., chemical mechanical
polishing (CMP).
[0007] There are a variety of depositions, chemicals, etc that form
on certain locations on substrates, as a result of electroplating,
that are desired to remove. For example, undesired deposits formed
from the plating material (such as copper) typically form on the
backside and/or edge of the substrate surface. Spin-rinse-dry (SRD)
and integrated bevel clean (IBC) systems are often used following
electroplating to remove the undesired deposits primarily
respectively on the backside and on the edge of the substrate. SRD
systems and IBC systems both involve the application of wet
etchants to the substrate to remove the undesired deposits on the
substrate. De-ionized water is applied to the substrate surfaces in
the SRD and IBC systems to rinse the etchant from the surface of
the substrate.
[0008] Crystals are another undesired substance that forms on
substrates. A chemical containing a metal, such as copper sulfate,
is contained within the electrolyte solution during processing. As
the substrate is removed from the electrolyte solution, some copper
sulfate crystals may remain on the substrate. As the electrolyte
solution dries on the surface of the substrate, some impurities
such as copper sulfate crystals are formed on a surface of the
substrate (the front side, the backside, the edge, etc.). As the
substrates are handled by robots, the copper sulfate crystals
contact the robots, certain portions of subsequent process cells,
and other system components. As further substrates are handled by
the robots, or processed within the process cells, the latter
substrates may also have contact with the crystals.
[0009] Therefore, there remains a need for system that limits the
formation of crystal material, deposited material, etc. on selected
areas of substrate surfaces during wet processes such as
electroplating.
SUMMARY OF THE INVENTION
[0010] Embodiments of the invention are generally directed to a
method of processing a semiconductor substrate in a processing
system segmented into a wet area and a dry area. The method
includes introducing the semiconductor substrate into the dry area
of the processing system, moving the semiconductor substrate into
the wet area of the processing system, processing the semiconductor
substrate in an electrochemical processing cell, and removing
unwanted deposits disposed on the semiconductor substrate during
processing.
[0011] Embodiments of the invention are also directed to an
electroplating system, which includes a wet area comprising one or
more electrochemical processing cells for processing one or more
semiconductor substrates in an electrolyte solution, a dry area for
transferring the semiconductor substrates to the wet area prior to
processing the semiconductor substrates and for receiving the
semiconductor substrates from the wet area after processing the
semiconductor substrates, and a cleaning module for removing
unwanted deposits from the semiconductor substrates after
processing the semiconductor substrates in the wet area but prior
to transferring the semiconductor substrates to the dry area.
[0012] In one embodiment, the cleaning module includes a housing, a
rotatable pedestal disposed in the housing, and a first plurality
of nozzles disposed around the housing for delivering rinsing fluid
to the surfaces of the semiconductor substrates.
[0013] In another embodiment, the dry area includes a thermal
chamber configured to anneal the semiconductor substrates after the
unwanted deposits are removed from the semiconductor
substrates.
[0014] In yet another embodiment, the cleaning module is disposed
in a substrate pathway between the one or more electrochemical
processing cells and the thermal anneal chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] So that the manner in which the above recited features,
advantages and objects of the present invention are attained can be
understood in detail, a more particular description of the
invention, briefly summarized above, may be had by reference to the
embodiments thereof which are illustrated in the appended
drawings.
[0016] FIG. 1 is a cross sectional view of a typical fountain
plater incorporating contacts;
[0017] FIG. 2 is a perspective view of one embodiment of a system
platform;
[0018] FIG. 3 is a top schematic view of the system platform of
FIG. 2;
[0019] FIG. 4 is a schematic perspective view of one embodiment of
a spin-rinse-dry (SRD) module, incorporating rinsing and dissolving
fluid inlets;
[0020] FIG. 5 is a side cross sectional view of the spin-rinse-dry
(SRD) module of FIG. 4 and shows a substrate in a processing
position vertically disposed between fluid inlets;
[0021] FIG. 6 is a cross sectional view of one embodiment of
electroplating process cell;
[0022] FIG. 7 is a partial cross sectional perspective view of one
embodiment of a cathode contact ring;
[0023] FIG. 8 is a cross sectional perspective view of the cathode
contact ring showing an alternative embodiment of contact pads;
[0024] FIG. 9 is a cross sectional perspective view of the cathode
contact ring showing an alternative embodiment of the contact pads
and an isolation gasket;
[0025] FIG. 10 is a cross sectional perspective view of the cathode
contact ring showing the isolation gasket;
[0026] FIG. 11 is a simplified schematic diagram of one embodiment
of the electrical circuit representing the electroplating system
through each contact;
[0027] FIG. 12 is a cross sectional view of one embodiment of one
embodiment of a substrate assembly;
[0028] FIG. 12A is an enlarged cross sectional view of one
embodiment of the bladder area of FIG. 12;
[0029] FIG. 13 is a partial cross sectional view of one embodiment
of a substrate holder plate;
[0030] FIG. 14 is a partial cross sectional view of one embodiment
of a manifold;
[0031] FIG. 15 is a partial cross sectional view of one embodiment
of a bladder;
[0032] FIG. 16 is a schematic diagram of one embodiment of an
electrolyte replenishing system;
[0033] FIG. 17 is a cross sectional view of one embodiment of a
rapid thermal anneal chamber;
[0034] FIG. 18 is a perspective view of an alternative embodiment
of a cathode contact ring;
[0035] FIG. 19 is a partial cross sectional view of an alternative
embodiment of a substrate holder assembly;
[0036] FIG. 20 is a cross sectional view of one embodiment of an
encapsulated anode;
[0037] FIG. 21 is a cross sectional view of another embodiment of
an encapsulated anode;
[0038] FIG. 22 is a cross sectional view of another embodiment of
an encapsulated anode;
[0039] FIG. 23 is a cross sectional view of yet another embodiment
of an encapsulated anode;
[0040] FIG. 24 is a top schematic view of one embodiment of a
mainframe transfer robot having a flipper robot incorporated
therein;
[0041] FIG. 25 is an alternative embodiment of the process head
assembly having a rotatable head assembly;
[0042] FIGS. 26a and 26b are cross sectional views of embodiments
of a degasser module; and
[0043] FIG. 27 is one embodiment of one embodiment of a method
performed by a controller during operation of the system
platform.
[0044] The terms "below", "above", "bottom", "top", "up", "down",
"upper", and "lower" and other positional terms used herein are
shown with respect to the embodiments in the figures and may be
varied depending on the specific relative orientation of the
processing apparatus.
[0045] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0046] This disclosure describes several embodiments of system
platforms that perform a series of processes. Some of the processes
are considered "wet" processes. Wet processes are those processes,
such as electroplating, that involve a liquid such as an
electrolyte solution. Electrolyte solution often contains a
chemical including the metal used for electroplating, such as
copper sulfate for copper electroplating. When the electrolyte
solution dries leaving a residue on the surface of a substrate, the
chemical (copper sulfate) takes the form of crystals that adhere to
the surface of the substrate and other surfaces on which the
electrolyte solution dries. If the substrate carries copper sulfate
crystals on its surface, other process cells, robots, etc. that
come in contact with the substrate can become coated with crystals.
The structure and operation of multiple embodiments of
electroplating systems are described. The segmenting of such system
platforms including electroplating systems (and other wet systems)
into wet and dry areas is then described. The wet areas are those
areas that the processing is performed. The dry areas are those
areas that the substrate is introduced into, or removed from, the
system platform.
[0047] Electroplating System and Operation
[0048] In this disclosure, the term "substrate" is intended to
describe substrates, wafers, or other objects that can be processed
within a system platform or fountain plater. The substrates are
generally cylindrical or rectangular, may be of any size (though
they commonly have a 200 mm or 300 mm diameter) and may include
such irregularities as notches or flatted surfaces that assist in
processing.
[0049] FIG. 1 shows one embodiment of fountain plater 10 used in
electroplating. The fountain plater 10 includes an electrolyte cell
12, a substrate holder 14, an anode 16, and a contact ring 20. The
electrolyte cell 12 contains electrolyte solution, and the
electrolyte cell has a top opening 21 circumferentially defined by
the contact ring 20. The substrate holder 14 is disposed above the
electrolyte cell, and is capable of displacing the substrate to be
immersed into, and removed out of, the electrolyte solution. The
substrate holder containing a substrate enters, and is removed
from, the electrolyte cell through the top opening of the
electrolyte cell. The contact ring 20 comprises a plurality of
metal or metal alloy electrical contacts that electrically contact
the seed layer on the substrate. A controller 222 controls the
electricity supplied to the anode. The controller 222 also controls
the electricity supplied to the seed layer on the substrate when
the seed layer is being plated. The controller thereby determines
the electrical current/voltage established across from the anode to
the seed layer on the substrate.
[0050] FIG. 2 is a perspective view of one embodiment of the system
platform 200 used in electroplating. FIG. 3 is a top schematic view
of the system platform 200 of FIG. 2. Referring to both FIGS. 2 and
3, the system platform 200 generally comprises a loading station
210, a rapid thermal anneal (RTA) chamber 211, a spin-rinse-dry
(SRD) station 212, a mainframe 214, the controller 222, and an
electrolyte solution replenishing system 220. Preferably, the
system platform 200 is enclosed in a clean environment using panels
made from such materials as PLEXIGLAS.RTM. (a registered trademark
of the Rohm and Haas Company of West Philadelphia, Pa.). The
mainframe 214 generally comprises a mainframe transfer station 216
and a plurality of processing stations 218. Each processing station
218 includes one or more process cells 240. An electrolyte solution
replenishing system 220 is positioned adjacent the system platform
200 and connected to the process cells 240 individually to
circulate electrolyte solution used for the electroplating
process.
[0051] The controller 222 comprises a central processing unit (CPU)
260, memory 262, circuit portion 265, input output interface (I/O)
279, and bus (not shown). The controller 222 may be a
general-purpose computer, a microprocessor, a microcontroller, or
any other known suitable type of computer or controller. The CPU
260 performs the processing and arithmetic operations for the
controller 222. The controller 222 controls the processing, robotic
operations, timing, etc. associated with the system platform 200.
The controller 222 controls the voltage applied to the anode 16,
the plating surface 15 of the substrate 22, and the operation of
the substrate holder assembly, one embodiment of which is shown as
450 in FIG. 6.
[0052] The memory 262 includes a random access memory (RAM) and a
read only memory (ROM) that together store the computer programs,
operands, operators, dimensional values, system processing
temperatures and configurations, and other parameters that control
the electroplating operation. The bus provides for digital
information transmissions between CPU 260, circuit portion 265,
memory 262, and I/O 279. The bus also connects I/O 279 to the
portions of the ECP system 200 that either receive digital
information from, or transmit digital information to, the
controller 222.
[0053] I/O 279 provides an interface to control the transmissions
of digital information between each of the components in controller
222. I/O 279 also provides an interface between the components of
the controller 222 and different portions of the ECP system 200.
Circuit portion 265 comprises all of the other user interface
devices (such as display and keyboard).
[0054] The loading station 210 preferably includes one or more
substrate cassette receiving areas 224, one or more loading station
transfer robots 228 and at least one substrate orientor 230. The
number of substrate cassette receiving areas, loading station
transfer robots 228 and substrate orientors included in the loading
station 210 can be configured according to the desired throughput
of the system. As shown for one embodiment in FIGS. 2 and 3, the
loading station 210 includes two substrate cassette receiving areas
224, two loading station transfer robots 228 and one substrate
orientor 230. A substrate cassette 232 containing substrates 234 is
loaded onto the substrate cassette receiving area 224 to introduce
substrates 234 into the system platform. The loading station
transfer robot 228 transfers substrates 234 between the substrate
cassette 232 and the substrate orientor 230. The loading station
transfer robot 228 comprises a typical transfer robot commonly
known in the art. The substrate orientor 230 positions each
substrate 234 in a desired orientation to ensure that the substrate
is properly processed. The loading station transfer robot 228 also
transfers substrates 234 between the loading station 210 and the
SRD station 212 and between the loading station 210 and the thermal
anneal chamber 211.
[0055] FIG. 4 is a schematic perspective view of one embodiment of
a spin-rinse-dry (SRD) module, incorporating rinsing and dissolving
fluid inlets. FIG. 5 is a side cross sectional view of the
spin-rinse-dry (SRD) module of FIG. 4 and shows a substrate in a
processing position vertically disposed between fluid inlets.
Preferably, the SRD station 212 includes one or more SRD modules
236 and one or more substrate pass-through cassettes 238.
Additionally, an integrated bevel clean (IBC) system 235, that is
also known as an edge bead removal module, can be applied to the
system platform 200 within the SRD station in close proximity to,
(and typically above) the SRD module 236. The IBC system 235 is
configured to remove unwanted deposits particularly from the edge
or bevel of a substrate. The IBC system 235 applies etchants to the
surface of the unwanted deposits, then applies de-ionized water to
remove the residue from the etched deposits. Preferably, the SRD
station 212 includes two SRD modules 236 corresponding to the
number of loading station transfer robots 228, and a substrate
pass-through cassette (the in-station) 238 is positioned above each
SRD module 236. The in-station 238 is typically positioned below
the level of the IBC system 235. The substrate pass-through
cassette 238 (also known as an in-station) facilitates substrate
transfer between the loading station 210 and the mainframe 214. The
substrate pass-through cassette 238 provides access to and from
both the loading station transfer robot 228 and a robot in the
mainframe transfer station 216.
[0056] Referring to FIGS. 4 and 5, the SRD module 236 comprises a
bottom 330a and a sidewall 330b, and an upper shield 330c which
collectively define a SRD module bowl 330d, where the shield
attaches to the sidewall and assists in retaining the fluids within
the SRD module. Alternatively, a removable cover that covers the
SRD module bowl could also be used. A pedestal 336, located in the
SRD module, includes a pedestal support 332 and a pedestal actuator
334. The pedestal 336 supports the substrate 338 (shown in FIG. 5)
on the pedestal upper surface during processing. The pedestal
actuator 334 rotates the pedestal to spin the substrate and raises
and lowers the pedestal as described below. The substrate may be
held in place on the pedestal by a plurality of clamps 337. The
clamps pivot with centrifugal force and engage the substrate
preferably in the edge exclusion zone of the substrate. In a
preferred embodiment, the clamps engage the substrate only when the
substrate lifts off the pedestal during the processing. Vacuum
passages (not shown) may also be used as well as other holding
elements. The pedestal has a plurality of pedestal arms 336a and
336b, so that the fluid through the second nozzle may impact as
much surface area on the lower surface on the substrate as is
practical. An outlet 339 allows fluid to be removed from the SRD
module.
[0057] A first conduit 346, through which a first fluid 347 flows,
is connected to a valve 347a. The conduit may be hose, pipe, tube,
or other fluid containing conduits. The valve 347a controls the
flow of the first fluid 347 and may be selected from a variety of
valves including a needle, globe, butterfly, or other valve types
and may include a valve actuator, such as a solenoid, that can be
controlled with a controller 222. The conduit 346 connects to a
first fluid inlet 340 that is located above the substrate and
includes a mounting portion 342 to attach to the SRD module and a
connecting portion 344 to attach to the conduit 346. The first
fluid inlet is shown with a single first nozzle 348 to deliver a
first fluid 347 under pressure onto the substrate upper surface.
However, multiple nozzles could be used and multiple fluid inlets
could be positioned about the inner perimeter of the SRD module.
Preferably, nozzles placed above the substrate should be outside
the diameter of the substrate to lessen the risk of the nozzles
dripping on the substrate. The first fluid inlet could be mounted
in a variety of locations, including through a cover positioned
above the substrate. Additionally, the nozzle may articulate to a
variety of positions using an articulating member 343, such as a
ball and socket joint.
[0058] Similar to the first conduit and related elements described
above, a second conduit 352 is connected to a control valve 349a
and a second fluid inlet 350 with a second nozzle 351. The second
fluid inlet 350 is shown below the substrate and angled upward to
direct a second fluid under the substrate through the second nozzle
351. Similar to the first fluid inlet, the second fluid inlet may
include a plurality of nozzles, a plurality of fluid inlets and
mounting locations, and a plurality of orientations including using
the articulating member 353. Each fluid inlet could be extended
into the SRD module at a variety of positions. For instance, if the
flow is desired to be a certain angle that is directed back toward
the SRD module periphery along the edge of the substrate. The
nozzles can be extended radially outward and the discharge from the
nozzles be directed back toward the SRD module periphery.
[0059] The controller 222 could individually control the two fluids
and their respective flow rates, pressure, and timing, and any
associated valving, as well as the spin cycle(s). The controller
could be remotely located, for instance, in a control panel or
control room and the plumbing controlled with remote actuators. An
alternative embodiment, shown in dashed lines, provides an
auxiliary fluid inlet 346a connected to the first conduit 346 with
a conduit 346b and having a control valve 346c. The alternate
embodiment may be used to flow a rinsing fluid on the backside of
the substrate after the dissolving fluid is applied. The rinsing
fluid may be applied without having to reorient the substrate or
switch the flow through the second fluid inlet to a rinsing
fluid.
[0060] In one embodiment, the substrate is mounted with the
deposition surface of the disposed face up in the SRD module bowl.
As will be explained below, for such an arrangement, the first
fluid inlet would generally flow a rinsing fluid. The rinsing fluid
is typically de-ionized water or alcohol. Consequently, the
backside of the substrate would be mounted facing down and a fluid
flowing through the second fluid inlet would be a dissolving fluid,
such as an acid, (the acid may be hydrochloric acid, sulfuric acid,
phosphoric acid, hydrofluoric acid, or other dissolving liquids or
fluids), depending on the deposits and material to be dissolved.
Alternatively, the first fluid and the second fluid are both
rinsing fluids, such as de-ionized water or alcohol, when the
desired process is only to rinse (and not etch) the processed
substrate.
[0061] In operation, the pedestal is in a raised position, shown in
FIG. 4, and a robot (not shown) places the substrate, front side
up, onto the pedestal. The pedestal lowers the substrate to a
processing position where the substrate is vertically disposed
between the first and the second fluid inlets. Generally, the
pedestal actuator rotates the pedestal between about 5 to about
5000 rpm, with a typical range between about 20 to about 2000 rpm
for a 200 mm substrate. The rotation causes the lower end 337a of
the clamps to rotate outward about pivot 337b, toward the periphery
of the SRD module sidewall, due to centrifugal force. The clamp
rotation forces the upper end 337c of the clamp inward and downward
to center and hold the substrate 338 in position on the pedestal
336, preferably along the substrate edge. The clamps may rotate
into position without touching the substrate and hold the substrate
in position on the pedestal only if the substrate significantly
lifts off the pedestal during processing.
[0062] With the pedestal rotating the substrate, a rinsing fluid is
delivered onto the substrate front side through the first fluid
inlet 340. The second fluid, such as an acid, is delivered to the
backside surface through the second fluid inlet to remove any
unwanted deposits. The dissolving fluid chemically reacts (to etch)
with the deposited material, dissolves, and then flushes the
material away from the substrate backside (and flushes the material
away from other areas that any unwanted deposits are located). In a
preferred embodiment, the rinsing fluid is adjusted to flow at a
greater rate than the dissolving fluid to help protect the front
side of the substrate from the dissolving fluid. The first and
second fluid inlets are located for optimal performance depending
on the size of the substrate, the respective flow rates, spray
patterns, and amount and type of deposits to be removed, among
other factors. In some instances, the rinsing fluid could be routed
to the second fluid inlet after a dissolving fluid has dissolved
the unwanted deposits to rinse the backside of the substrate. In
other instances, an auxiliary fluid inlet connected to flow rinsing
fluid on the backside of the substrate could be used to rinse any
dissolving fluid residue from the backside. After rinsing the front
side and/or backside of the substrate, the fluid(s) flow is stopped
and the pedestal continues to rotate, spinning the substrate, and
thereby effectively drying the surface.
[0063] The fluid(s) is generally delivered in a spray pattern,
which may be varied depending on the particular nozzle spray
pattern desired and may include a fan, jet, conical, and other
patterns. One spray pattern for the first and second fluids through
the respective fluid inlets, when the first fluid is a rinsing
fluid, is fan pattern with a pressure of about 10 to about 15
pounds per square inch (psi) and a flow rate of about 1 to about 3
gallons per minute (gpm) (for a 200 mm substrate).
[0064] The SRD module could also be used to remove the unwanted
deposits along the edge of the substrate to create an edge
exclusion zone. The unwanted deposits could be removed from the
edge and/or edge exclusion zone of the substrate by adjustment of
the orientation and placement of the nozzles, the flow rates of the
fluids, the rotational speed of the substrate, and the chemical
composition of the fluids. Thus, substantially preventing
dissolution of the deposited material on the front side surface may
not necessarily include the edge or edge exclusion zone of the
substrate. Also, preventing dissolution of the deposited material
on the front side surface is intended to include at least
preventing the dissolution so that the front side with the
deposited material is not impaired beyond a commercial value.
[0065] One method of accomplishing the edge exclusion zone
dissolution process is to rotate the disk at a slower speed, such
as about 100 to about 1000 rpm, while dispensing the dissolving
fluid on the backside of the substrate. The centrifugal force moves
the dissolving fluid to the edge of the substrate and forms a layer
of fluid around the edge due to surface tension of the fluid, so
that the dissolving fluid overlaps from the backside to the front
side in the edge area of the substrate. The rotational speed of the
substrate and the flow rate of the dissolving fluid may be used to
determine the extent of the overlap onto the front side. For
instance, a decrease in rotational speed or an increase in flow
results in a less overlap of fluid to the opposing side, e.g., the
front side. Additionally, the flow rate and flow angle of the
rinsing fluid delivered to the front side can be adjusted to offset
the layer of dissolving fluid onto the edge and/or front side of
the substrate. In some instances, the dissolving fluid may be used
initially without the rinsing fluid to obtain the edge and/or edge
exclusion zone removal, followed by the rinsing/dissolving process
of the SRD module.
[0066] The SRD module 236 is connected between the loading station
210 and the mainframe 214. The mainframe 214 generally comprises a
mainframe transfer station 216 and a plurality of processing
stations 218. Referring to FIGS. 2 and 3, the mainframe 214, as
shown, includes two processing stations 218, each processing
station 218 having two process cells 240. The mainframe transfer
station 216 includes a mainframe transfer robot 242. Preferably,
the mainframe transfer robot 242 comprises a plurality of
individual robot arms 244 that provides independent access of
substrates in the processing stations 218 and the SRD stations 212.
As shown in FIG. 3, the mainframe transfer robot 242 comprises two
robot arms 244, corresponding to the number of process cells 240
per processing station 218. Each robot arm 244 includes a robot
blade 246 for holding a substrate during a substrate transfer.
Preferably, each robot arm 244 is operable independently of the
other arm to facilitate independent transfers of substrates in the
system. Alternatively, the robot arms 244 operate in a linked
fashion such that one robot extends as the other robot arm
retracts.
[0067] Preferably, the mainframe transfer station 216 includes a
flipper robot 248 that facilitates transfer of a substrate from a
face-up position on the robot blade 246 of the mainframe transfer
robot 242 to a face down position for a process cell 240 that
requires face-down processing of substrates. The flipper robot 248
includes a main body 250 that provides both vertical and rotational
movements with respect to a vertical axis of the main body 250 and
a flipper robot arm 252 that provides rotational movement along a
horizontal axis along the flipper robot arm 252. Preferably, a
vacuum suction gripper 254, disposed at the distal end of the
flipper robot arm 252, holds the substrate as the substrate is
flipped and transferred by the flipper robot 248. The flipper robot
248 positions a substrate 234 into the process cell 240 for
face-down processing. The details of the electroplating process
cell will be discussed below.
[0068] FIG. 24 is a top schematic view of a mainframe transfer
robot having a flipper robot incorporated therein. The mainframe
transfer robot 242 as shown in FIG. 24 serves to transfer
substrates between different stations attached the mainframe
station, including the processing stations and the SRD stations.
The mainframe transfer robot 242 includes a plurality of robot arms
2402 (two shown), and a flipper robot 2404 is attached as an end
effector for each of the robot arms 2402. Flipper robots are
generally known in the art and can be attached as end effectors for
substrate handling robots, such as model RR701, available from
Rorze Automation, Inc., located in Milpitas, Calif. The main
transfer robot 242 comprising a flipper robot as the end effector
is capable of transferring substrates between different stations
attached to the mainframe as well as flipping the substrate being
transferred to the desired surface orientation, i.e., substrate
processing surface being face-down for the electroplating process.
Preferably, the mainframe transfer robot 242 provides independent
robot motion along the X-Y-Z axes by the robot arm 2402 and
independent substrate flipping rotation by the flipper robot end
effector 2404. By incorporating the flipper robot 2404 as the end
effector of the mainframe transfer robot, the substrate transfer
process is simplified because the step of passing a substrate from
a mainframe transfer robot to a flipper robot is eliminated.
[0069] FIG. 6 is a cross sectional view of one embodiment of an
electroplating process cell 400. The electroplating process cell
400 as shown in FIG. 6 may be the same electroplating process cell
240 shown in FIGS. 2 and 3. The process cell 400 generally
comprises a head assembly 410, a process cell 420 and an
electrolyte solution collector 440. Preferably, the electrolyte
solution collector 440 is secured onto the body 442 of the
mainframe 214 over an opening 443 that defines the location for
placement of the process cell 420. The electrolyte solution
collector 440 includes an inner wall 446, an outer wall 448 and a
bottom 447 connecting the walls. An electrolyte solution outlet 449
is disposed through the bottom 447 of the electrolyte solution
collector 440 and connected to the electrolyte solution
replenishing system 220 (shown in FIG. 2) through tubes, hoses,
pipes or other fluid transfer connectors.
[0070] The head assembly 410 is mounted onto a head assembly frame
452. The head assembly frame 452 includes a mounting post 454 and a
cantilever arm 456. The mounting post 454 is mounted onto the body
442 of the mainframe 214, and the cantilever arm 456 extends
laterally from an upper portion of the mounting post 454.
Preferably, the mounting post 454 provides rotational movement with
respect to a vertical axis along the mounting post to allow
rotation of the head assembly 410. The head assembly 410 is
attached to a mounting plate 460 disposed at the distal end of the
cantilever arm 456. The lower end of the cantilever arm 456 is
connected to a cantilever arm actuator 457, such as a pneumatic
cylinder, mounted on the mounting post 454. The cantilever arm
actuator 457 provides pivotal movement of the cantilever arm 456
with respect to the joint between the cantilever arm 456 and the
mounting post 454. When the cantilever arm actuator 457 is
retracted, the cantilever arm 456 moves the head assembly 410 away
from the process cell 420 to provide the spacing required to remove
and/or replace the process cell 420 from the electroplating process
cell 400. When the cantilever arm actuator 457 is extended, the
cantilever arm 456 moves the head assembly 410 toward the process
cell 420 to position the substrate in the head assembly 410 in a
processing position.
[0071] The head assembly 410 generally comprises a substrate holder
assembly 450 and a substrate assembly actuator 458. The substrate
assembly actuator 458 is mounted onto the mounting plate 460, and
includes a head assembly shaft 462 extending downwardly through the
mounting plate 460. The lower end of the head assembly shaft 462 is
connected to the substrate holder assembly 450 to position the
substrate holder assembly 450 in a processing position and in a
substrate loading position.
[0072] The substrate holder assembly 450 generally comprises a
substrate holder 464 and an electric contact element 466. FIG. 7 is
a cross sectional view of one embodiment of an electric contact
element 466. In general, the electric contact element 466 comprises
an annular body having a plurality of conducting members disposed
thereon. The annular body is constructed of an insulating material
to electrically isolate the plurality of conducting members.
Together the body and conducting members form a diametrically
interior substrate seating surface which, during processing,
supports a substrate and provides a current thereto.
[0073] Referring now to FIG. 7 in detail, the electric contact
element 466 generally comprises a plurality of conducting members
765 at least partially disposed within an annular insulative body
770. The insulative body 770 is shown having a flange 762 and a
downward sloping shoulder portion 764 leading to a substrate
seating surface 768 located below the flange 762. The flange 762
and the substrate seating surface 768 lie in offset and
substantially parallel planes. Thus, the flange 762 may be
understood to define a first plane while the substrate seating
surface 768 defines a second plane parallel to the first plane
wherein the shoulder 764 is disposed between the two planes.
However, the electric contact element design shown in FIG. 7 is
intended to be merely illustrative. In another embodiment, the
shoulder portion 764 may be of a steeper angle including a
substantially vertical angle so as to be substantially normal to
both the flange 762 and the substrate seating surface 768.
Alternatively, the electric contact element 466 may be
substantially planar thereby eliminating the shoulder portion 764.
However, for reasons described below, a preferred embodiment
comprises the shoulder portion 764 shown in FIG. 6 or some
variation thereof.
[0074] The conducting members 765 are defined by a plurality of
outer electrical contact pads 780 annularly disposed on the flange
762, a plurality of inner electrical contact pads 772 disposed on a
portion of the substrate seating surface 768, and a plurality of
embedded conducting connectors 776 which link the pads 772, 780 to
one another. The conducting members 765 are isolated from one
another by the insulative body 770. The insulative body may be made
of a plastic such as polyvinylidenefluoride (PVDF), perfluoroalkoxy
resin (PFA), Teflon.RTM. (a registered trademark of the E. l.
duPont de Nemours and Company) and Tefzel.TM., or any other
insulating material such as Alumina (Al.sub.2O.sub.3) or other
ceramics. The outer contact pads 780 are coupled to a power supply
(not shown) to deliver current and voltage to the inner contact
pads 772 via the connectors 776 during processing. In turn, the
inner contact pads 772 supply the current and voltage to a
substrate by maintaining contact around a peripheral portion of the
substrate. Thus, in operation the conducting members 765 act as
discrete current paths electrically connected to a substrate.
[0075] Low resistivity, and conversely high conductivity, are
directly related to good plating. To ensure low resistivity, the
conducting members 765 are preferably made of copper (Cu), platinum
(Pt), tantalum (Ta), titanium (Ti), gold (Au), silver (Ag),
stainless steel or other conducting materials. Low resistivity and
low contact resistance may also be achieved by coating the
conducting members 765 with a conducting material. Thus, the
conducting members 765 may, for example, be made of copper
(resistivity for copper is approximately 2.times.10.sup.-8
.OMEGA..multidot.m) and be coated with platinum (resistivity for
platinum is approximately 10.6.times.10.sup.-8 .OMEGA..multidot.m).
Coatings such as tantalum nitride (TaN), titanium nitride (TiN),
rhodium (Rh), Au, Cu, or Ag on a conductive base materials such as
stainless steel, molybdenum (Mo), Cu, and Ti are also possible.
Further, since the contact pads 772, 780 are typically separate
units bonded to the conducting connectors 776, the contact pads
772, 780 may comprise one material, such as Cu, and the conducting
members 765 another, such as stainless steel. Either or both of the
pads 772, 180 and conducting connectors 776 may be coated with a
conducting material. Additionally, because plating repeatability
may be adversely affected by oxidation that acts as an insulator,
the inner contact pads 772 preferably comprise a material resistant
to oxidation such as Pt, Ag, or Au.
[0076] In addition to being a function of the contact material, the
total resistance of each circuit is dependent on the geometry, or
shape, of the inner contact inner contact pads 772 and the force
supplied by the contact ring 466. These factors define a
constriction resistance, R.sub.CR, at the interface of the inner
contact pads 772 and the substrate seating surface 768 due to
asperities between the two surfaces. Generally, as the applied
force is increased the apparent area is also increased. The
apparent area is, in turn, inversely related to R.sub.CR so that an
increase in the apparent area results in a decreased R.sub.CR.
Thus, to minimize overall resistance it is preferable to maximize
force. The maximum force applied in operation is limited by the
yield strength of a substrate which may be damaged under excessive
force and resulting pressure. However, because pressure is related
to both force and area, the maximum sustainable force is also
dependent on the geometry of the inner contact pads 772. Thus,
while the contact pads 772 may have a flat upper surface as in FIG.
7, other shapes may be used to advantage. For example, two
preferred shapes are shown in FIGS. 8 and 9. FIG. 8 shows a
knife-edge contact pad and FIG. 9 shows a hemispherical contact
pad. A person skilled in the art will readily recognize other
shapes which may be used to advantage. A more complete discussion
of the relation between contact geometry, force, and resistance is
given in Ney Contact Manual, by Kenneth E. Pitney, The J. M. Ney
Company, 1973, which is hereby incorporated by reference in its
entirety.
[0077] The number of connectors 776 may be varied depending on the
particular number of contact pads 772 (shown in FIG. 7) desired.
For a 200 mm substrate, preferably at least twenty-four connectors
776 are spaced equally over 360.degree.. However, as the number of
connectors reaches a critical level, the compliance of the
substrate relative to the contact ring 466 is adversely affected.
For symmetry, it may be desired to provide a number of conductors
that can be equally spaced about the perimeter of the substrate.
For instance, a multiple number of eight conductors (8, 16, 24,
etc) may be used since this provides an easily determinable and
measurable angle between the conductors. Therefore, while more than
twenty-four connectors 776 may be used, contact uniformity may
eventually diminish depending on the topography of the contact pads
772 and the substrate stiffness. Similarly, while less than
twenty-four connectors 776 may be used, current flow is
increasingly restricted and localized, leading to poor plating
results. Since the dimensions of the process cell can be configured
to suit a particular application. For example, the dimensions would
be changed to compensate between a 200 and a 300 mm substrate.
[0078] As shown in FIG. 10, the substrate seating surface 768
comprises an isolation gasket 782. The isolation gasket is disposed
on the insulative body 770 and extends diametrically interior to
the inner contact pads 772 to define the inner diameter of the
contact ring 466. The isolation gasket 782 preferably extends
slightly above the inner contact pads 772 (e.g., a few mils) and
preferably comprises an elastomer such as VITON.RTM. (a registered
trademark of the E. l. duPont de Nemours and Company of Wilmington,
Del.), TEFLON.RTM. (a registered trademark of the E. l. duPont de
Nemours and Company of Wilmington, Del.), buna rubber and the like.
Where the insulative body 770 also comprises an elastomer the
isolation gasket 782 may be of the same material. In the latter
embodiment, the isolation gasket 782 and the insulative body 770
may be monolithic, i.e., formed as a single piece. However, the
isolation gasket 782 is preferably separate from the insulative
body 770 so that it may be easily removed for replacement or
cleaning.
[0079] While FIG. 10 shows a preferred embodiment of the isolation
gasket 782 wherein the isolation gasket is seated entirely on the
insulative body 770, FIGS. 8 and 9 show an alternative embodiment.
In the latter embodiment, the insulative body 770 is partially
machined away to expose the upper surface of the connecting member
776 and the isolation gasket 782 is disposed thereon. Thus, the
isolation gasket 782 contacts a portion of the connecting member
776. This design requires less material to be used for the inner
contact pads 772 that may be advantageous where material costs are
significant such as when the inner contact pads 772 comprise
gold.
[0080] During processing, the isolation gasket 782 maintains
contact with a peripheral portion of the substrate plating surface
and is compressed to provide a seal between the remaining electric
contact element 466 and the substrate. The seal prevents the
electrolyte solution from contacting the edge and backside of the
substrate. As noted above, maintaining a clean contact surface is
necessary to achieving high plating repeatability. Previous contact
ring designs did not provide consistent plating results because
contact surface topography varied over time. The contact ring
limits, or substantially minimizes, deposits which would otherwise
accumulate on the inner contact pads 772 and change their
characteristics thereby producing highly repeatable, consistent,
and uniform plating across the substrate plating surface.
[0081] FIG. 11 is a simplified schematic diagram representing a
possible configuration of the electrical circuit for the contact
ring 466. To provide a uniform current distribution between the
conducting members 765, an external resistor 700 is connected in
series with each of the conducting members 765. Preferably, the
resistance value of the external resistor 700 (represented as
R.sub.EXT) is much greater than the resistance of any other
component of the circuit. As shown in FIG. 11, the electrical
circuit through each conducting member 765 is represented by the
resistance of each of the components connected in series with the
power supply 702. R.sub.E represents the resistance of the
electrolyte solution, which is typically dependent on the distance
between the anode and the cathode contact ring and the chemical
composition of the electrolyte solution. Thus, R.sub.A represents
the resistance of the electrolyte solution adjacent the substrate
plating surface 754. R.sub.S represents the resistance of the
substrate plating surface 754, and R.sub.C represents the
resistance of the cathode conducting members 765 plus the
constriction resistance resulting at the interface between the
inner contact pads 772 and the substrate plating layer 754.
Generally, the resistance value of the external resistor
(R.sub.EXT) is at least as much as .SIGMA.R (where .SIGMA.R equals
the sum of R.sub.E, R.sub.A, R.sub.S and R.sub.C). Preferably, the
resistance value of the external resistor (R.sub.EXT) is much
greater than .SIGMA.R such that .SIGMA.R is negligible and the
resistance of each series circuit approximates R.sub.EXT.
[0082] Typically, one power supply is connected to all of the outer
contact pads 780 of the electric contact element 466, resulting in
parallel circuits through the inner contact pads 772. However, as
the inner contact pad-to-substrate interface resistance varies with
each inner contact pad 772, more current will flow, and thus more
plating will occur, at the site of lowest resistance. However, by
placing an external resistor in series with each conducting member
765, the value or quantity of electrical current passed through
each conducting member 765 becomes controlled mainly by the value
of the external resistor. As a result, the variations in the
electrical properties between each of the inner contact pads 772 do
not affect the current distribution on the substrate. The uniform
current density applied across the plating surface contributes to a
uniform plating thickness of the metal film deposited on the seed
layer on the substrate. The external resistors also provide a
uniform current distribution between different substrates of a
process-sequence.
[0083] Although the contact ring 466 is designed to resist deposit
buildup on the inner contact pads 772, over multiple substrate
plating cycles the substrate-pad interface resistance may increase,
eventually reaching an unacceptable value. An electronic
sensor/alarm 704 can be connected across the external resistor 700
to monitor the voltage/current across the external resistor to
address this problem. If the voltage/current across the external
resistor 700 falls outside of a preset operating range that is
indicative of a high substrate-pad resistance, the sensor/alarm 704
triggers corrective measures such as shutting down the plating
process until the problems are corrected by an operator.
Alternatively, a separate power supply can be connected to each
conducting member 765 and can be separately controlled and
monitored to provide a uniform current distribution across the
substrate. A very smart system (VSS) may also be used to modulate
the current flow. The VSS typically comprises a processing unit and
any combination of devices known in the industry used to supply
and/or control current such as variable resistors, separate power
supplies, etc. As the physiochemical, and hence electrical,
properties of the inner contact pads 772 change over time, the VSS
processes and analyzes data feedback. The data is compared to
pre-established setpoints and the VSS then makes appropriate
current and voltage alterations to ensure uniform deposition.
[0084] FIG. 18 is a perspective view of an alternative embodiment
of a cathode contact ring. The cathode contact ring 1800 as shown
in FIG. 18 comprises a conductive metal or a metal alloy, such as
stainless steel, copper, silver, gold, platinum, titanium,
tantalum, and other conductive materials, or a combination of
conductive materials, such as stainless steel coated with platinum.
The cathode contact ring 1800 includes an upper mounting portion
1810 adapted for mounting the cathode contact ring onto the
substrate holder assembly and a lower substrate receiving portion
1820 adapted for receiving a substrate therein. The substrate
receiving portion 1820 includes an annular substrate seating
surface 1822 having a plurality of contact pads or bumps 1824
disposed thereon and preferably evenly spaced apart. When a
substrate is positioned on the substrate seating surface 1822, the
contact pads 1824 physically contact a peripheral region of the
substrate to provide electrical contact to the seed layer formed on
the substrate. Preferably, the contact pads 1824 are coated with a
noble metal, such as platinum or gold, that is resistant to
oxidation.
[0085] The exposed surfaces of the cathode contact ring, except the
surfaces of the contact pads that come in contact with the
substrate, are preferably treated to provide hydrophilic surfaces
or coated with a material that exhibits hydrophilic properties.
Hydrophilic materials and hydrophilic surface treatments are known
in the art. One company providing a hydrophilic surface treatment
is Millipore Corporation, located in Bedford, Massachusetts. The
hydrophilic surface significantly reduces beading of the
electrolyte solution on the surfaces of the cathode contact ring
and promotes smooth dripping of the electrolyte solution from the
cathode contact ring after the cathode contact ring is removed from
the electroplating bath or electrolyte solution. By providing
hydrophilic surfaces on the cathode contact ring that facilitate
run-off of the electrolyte solution, plating defects caused by
residual electrolyte solution on the cathode contact ring are
significantly reduced. The inventors also contemplate application
of this hydrophilic treatment or coating in other embodiments of
cathode contact rings to reduce residual electrolyte solution
beading on the cathode contact ring and the plating defects on a
subsequently processed substrate that may result therefrom.
[0086] Referring to FIGS. 12 and 12A, the substrate holder 464 is
preferably positioned above the electric contact element 466 and
comprises a bladder assembly 470 that provides pressure to the
backside of a substrate and ensures electrical contact between the
substrate plating surface and the electric contact element 466. The
inflatable bladder assembly 470 is disposed on a substrate holder
plate 832. A bladder 836 disposed on a lower surface of the
substrate holder plate 832 is thus located opposite and adjacent to
the contacts on the electric contact element 466 with the substrate
821 interposed therebetween. A fluid source 838 supplies a fluid,
i.e., a gas or liquid, to the bladder 836 allowing the bladder 836
to be inflated to varying degrees.
[0087] Referring now to FIGS. 12, 12A, and 13, the details of the
bladder assembly 470 will be discussed. The substrate holder plate
832 is shown as substantially disc-shaped having an annular recess
840 formed on a lower surface and a centrally disposed vacuum port
841. One or more inlets 842 are formed in the substrate holder
plate 832 and lead into the relatively enlarged annular mounting
channel 843 and the annular recess 840. Quick-disconnect hoses 844
couple the fluid source 838 to the inlets 842 to provide a fluid
thereto. The vacuum port 841 is preferably attached to a
vacuum/pressure pumping system 859 adapted to selectively supply a
pressure or create a vacuum at a backside of the substrate 821. The
pumping system 859, shown in FIG. 12, comprises a pump 858, a
cross-over valve 847, and a vacuum ejector 849 (commonly known as a
venturi). One vacuum ejector that may be used is available from SMC
Pneumatics, Inc., of Indianapolis, Indiana. The pump 858 may be a
commercially available compressed gas source and is coupled to one
end of a hose 847, the other end of the hose 847 being coupled to
the vacuum port 841. The hose 847 is split into a pressure line 853
and a vacuum line 855 having the vacuum ejector 849 disposed
therein. Fluid flow is controlled by the cross-over valve 847 which
selectively switches communication with the pump 858 between the
pressure line 853 and the vacuum line 855. Preferably, the
cross-over valve has an OFF setting whereby fluid is restricted
from flowing in either direction through hose 847. A shut-off valve
861 disposed in hose 847 prevents fluid from flowing from pressure
line 855 upstream through the vacuum ejector 849. The desired
direction of fluid flow is indicated by arrows.
[0088] Where the fluid source 838 is a gas supply it may be coupled
to hose 847 thereby eliminating the need for a separate compressed
gas supply, i.e., pump 858. Further, a separate gas supply and
vacuum pump may supply the backside pressure and vacuum conditions.
While it is preferable to allow for both a backside pressure as
well as a backside vacuum, a simplified embodiment may comprise a
pump capable of supplying only a backside vacuum. However, as will
be explained below, deposition uniformity may be improved where a
backside pressure is provided during processing. Therefore, an
arrangement such as the one described above including a vacuum
ejector and a cross-over valve is preferred.
[0089] Referring now to FIGS. 12A and 14, a substantially circular
ring-shaped manifold 846 is disposed in the annular recess 840. The
manifold 846 comprises a mounting rail 852 disposed between an
inner shoulder 848 and an outer shoulder 850. The mounting rail 852
is adapted to be at least partially inserted into the annular
mounting channel 843. A plurality of fluid outlets 854 formed in
the manifold 846 provide communication between the inlets 842 and
the bladder 836. Seals 837, such as O-rings, are disposed in the
annular manifold channel 843 in alignment with the inlet 842 and
outlet 854 and secured by the substrate holder plate 832 to ensure
an airtight seal. Conventional fasteners (not shown) such as screws
may be used to secure the manifold 846 to the substrate holder
plate 832 via cooperating threaded bores (not shown) formed in the
manifold 846 and the substrate holder plate 832.
[0090] Referring now to FIG. 15, the bladder 836 is shown, in
section, as an elongated substantially semi-tubular piece of
material having annular lip seals 856, or nodules, at each edge. In
FIG. 12A, the lip seals 856 are shown disposed on the inner
shoulder 848 and the outer shoulder 850. A portion of the bladder
836 is compressed against the walls of the annular recess 840 by
the manifold 846 which has a width slightly less (e.g. a few
millimeters) than the annular recess 840. Thus, the manifold 846,
the bladder 836, and the annular recess 840 cooperate to form a
fluid-tight seal. To prevent fluid loss, the bladder 836 is
preferably comprised of some fluid impervious material such as
silicon rubber or any comparable elastomer which is chemically
inert with respect to the electrolyte solution and exhibits
reliable elasticity. Where needed a compliant covering 857 may be
disposed over the bladder 836, as shown in FIG. 15, and secured by
means of an adhesive or thermal bonding. The covering 857
preferably comprises an elastomer such as Viton.TM., buna rubber or
the like, which may be reinforced by KEVLAR.RTM. (a registered
trademark of the E. l. DuPont de Nemours and Company of Wilmington,
Del.), for example. In one embodiment, the covering 857 and the
bladder 836 comprise the same material. The covering 857 has
particular application where the bladder 836 is susceptible to
rupturing. Alternatively, the bladder 836 thickness may simply be
increased during its manufacturing to reduce the likelihood of
puncture. Preferably, the exposed surface of the bladder 836 (if
uncovered) and the exposed surface of the covering 857 are coated
or treated to provide a hydrophilic surface (as discussed above for
the surfaces of the cathode contact ring). This coating promotes
dripping and removal of the residual electrolyte solution after the
head assembly is lifted above the process cell.
[0091] The precise number of inlets 842 and outlets 854 may be
varied according to the particular application. For example, while
FIG. 12 shows two inlets with corresponding outlets, an alternative
embodiment could employ a single fluid inlet that supplies fluid to
the bladder 836.
[0092] In operation, the substrate 821 is introduced into the
container body 802 by securing it to the lower side of the
substrate holder plate 832. This is accomplished by engaging the
pumping system 859 to evacuate the space between the substrate 821
and the substrate holder plate 832 via port 841 thereby creating a
vacuum condition. The bladder 836 is then inflated by supplying a
fluid such as air or water from the fluid source 838 to the inlets
842. The fluid is delivered into the bladder 836 via the manifold
outlets 854, thereby pressing the substrate 821 uniformly against
the contacts of the electric contact element 466. The
electroplating process is then carried out. Electrolyte solution is
then pumped into the process cell 420 toward the substrate 821 to
contact the exposed substrate plating surface 820. The power supply
provides a negative bias to the substrate plating surface 820 via
the electric contact element 466. As the electrolyte solution is
flowed across the substrate plating surface 820, ions in the
electrolytic solution are attracted to the surface 820 and deposit
on the surface 820 to form the desired film.
[0093] Because of its flexibility, the bladder 836 deforms to
accommodate the asperities of the substrate backside and contacts
of the electric contact element 466 thereby mitigating misalignment
with the conducting electric contact element 466. The compliant
bladder 836 prevents the electrolyte solution from flowing to the
backside of the substrate 821 by establishing a fluid tight seal at
a portion close to the perimeter of a backside of the substrate
821. Once inflated, a uniform pressure is delivered downward toward
the electric contact element 466 to achieve substantially equal
force at all points where the substrate 821 and electric contact
element 466 interface. The force can be varied as a function of the
pressure supplied by the fluid source 838. Further, the
effectiveness of the bladder assembly 470 is not dependent on the
configuration of the electric contact element 466. For example,
while FIG. 12 shows a pin configuration having a plurality of
discrete contact points, the electric contact element 466 may also
be a continuous surface.
[0094] Because the force delivered to the substrate 821 by the
bladder 836 is variable, adjustments can be made to the current
flow supplied by the contact ring 466. As described above, an oxide
layer may form on the electric contact element 466 and act to
restrict current flow. However, increasing the pressure of the
bladder 836 may counteract the current flow restriction due to
oxidation. As the pressure is increased, the malleable oxide layer
is compromised and superior contact between the electric contact
element 466 and the substrate 821 results. The effectiveness of the
bladder 836 in this capacity may be further improved by altering
the geometry of the electric contact element 466. For example, a
knife-edge geometry is likely to penetrate the oxide layer more
easily than a dull rounded edge or flat edge.
[0095] Additionally, the fluid tight seal provided by the inflated
bladder 836 allows the pump 858 to maintain a backside vacuum or
pressure either selectively or continuously, before, during, and
after processing. Generally, however, the pump 858 is run to
maintain a vacuum only during the transfer of substrates to and
from the electroplating process cell 400 because it has been found
that the bladder 836 is capable of maintaining the backside vacuum
condition during processing without continuous pumping. Thus, while
inflating the bladder 836, as described above, the backside vacuum
condition is simultaneously relieved by disengaging the pumping
system 859, e.g., by selecting an off position on the cross-over
valve 847. Disengaging the pumping system 859 may be abrupt or
comprise a gradual process whereby the vacuum condition is ramped
down. Ramping allows for a controlled exchange between the
inflating bladder 836 and the simultaneously decreasing backside
vacuum condition. This exchange may be controlled manually or by
computer.
[0096] As described above, continuous backside vacuum pumping while
the bladder 836 is inflated is not needed and may actually cause
the substrate 820 to buckle or warp leading to undesirable
deposition results. It may be desirable to provide a backside
pressure to the substrate 820 in order to cause a "bowing" effect
of the substrate to be processed. Bowing of the substrate may
results in superior deposition on the substrate. Thus, pumping
system 859 is capable of selectively providing a vacuum or pressure
condition to the substrate backside. For a 200 mm substrate a
backside pressure up to 5 psi is preferable to bow the substrate.
Because substrates typically exhibit some measure of pliability, a
backside pressure causes the substrate to bow or assume a convex
shape relative to the upward flow of the electrolyte solution. The
degree of bowing is variable according to the pressure supplied by
pumping system 859.
[0097] Those skilled in the art will readily recognize other
embodiments. For example, while FIG. 12A shows a preferred bladder
836 having a surface area sufficient to cover a relatively small
perimeter portion of the substrate backside at a diameter
substantially equal to the electric contact element 466. The
geometric configuration of the bladder assembly 470 can be varied.
Thus, the bladder assembly may be constructed using more fluid
impervious material to cover an increased surface area of the
substrate 821.
[0098] FIG. 19 is a partial cross sectional view of an alternative
embodiment of a substrate holder assembly. The alternative
substrate holder assembly 1900 comprises a bladder assembly 470, as
described above, having the inflatable bladder 836 attached to the
back surface of an intermediary substrate holder plate 1910.
Preferably, a portion of the inflatable bladder 836 is sealingly
attached to the back surface 1912 of the intermediary substrate
holder plate 1910 using an adhesive or other bonding material. The
front surface 1914 of the intermediary substrate holder plate 1910
is adapted to receive a substrate 821 to be processed. An
elastomeric o-ring 1916 is disposed in an annular groove 1918 on
the front surface 1914 of the intermediary substrate holder plate
1910 to contact a peripheral portion of the substrate back surface.
The elastomeric o-ring 1916 provides a seal between the substrate
back surface and the front surface of the intermediary substrate
holder plate. Preferably, the intermediary substrate holder plate
includes a plurality of bores or holes 1920 extending through the
plate that are in fluid communication with the vacuum port 841. The
plurality of holes 1920 facilitate securing the substrate on the
substrate holder using a vacuum force applied to the backside of
the substrate. According to this alternative embodiment of the
substrate holder assembly, the inflatable bladder does not directly
contact a substrate being processed, and thus the risk of cutting
or damaging the inflatable bladder during substrate transfers is
significantly reduced. The elastomeric O-ring 1916 is preferably
coated or treated to provide a hydrophilic surface (as discussed
above for the surfaces of the cathode contact ring) for contacting
the substrate. The elastomeric O-ring 1916 is replaced as needed to
ensure proper contact and seal to the substrate.
[0099] FIG. 25 is an alternative embodiment of the process head
assembly having a rotatable head assembly 2410. Preferably, a
rotational actuator is disposed on the cantilevered arm and
attached to the head assembly to rotate the head assembly during
substrate processing. The rotatable head assembly 2410 is mounted
onto a head assembly frame 2452. The alternative head assembly
frame 2452 and the rotatable head assembly 2410 are mounted onto
the mainframe similarly to the head assembly frame 452 and head
assembly 410 as shown in FIG. 6 and described above. The head
assembly frame 2452 includes a mounting post 2454, a post cover
2455, and a cantilever arm 2456. The mounting post 2454 is mounted
onto the body of the mainframe 214, and the post cover 2455 covers
a top portion of the mounting post 2454. Preferably, the mounting
post 2454 provides rotational movement (as indicated by arrow Al)
with respect to a vertical axis along the mounting post to allow
rotation of the head assembly frame 2452. The cantilever arm 2456
extends laterally from an upper portion of the mounting post 2454
and is pivotally connected to the post cover 2455 at the pivot
joint 2459. The rotatable head assembly 2410 is attached to a
mounting slide 2460 disposed at the distal end of the cantilever
arm 2456. The mounting slide 2460 guides the vertical motion of the
head assembly 2410. A head lift actuator 2458 is disposed on top of
the mounting slide 2460 to provide vertical displacement of the
head assembly 2410.
[0100] The lower end of the cantilever arm 2456 is connected to the
shaft 2453 of a cantilever arm actuator 2457, such as a pneumatic
cylinder or a lead-screw actuator, mounted on the mounting post
2454. The cantilever arm actuator 2457 provides pivotal movement
(as indicated by arrow A2) of the cantilever arm 2456 with respect
to the joint 2459 between the cantilever arm 2456 and the post
cover 2454. When the cantilever arm actuator 2457 is retracted, the
cantilever arm 2456 moves the head assembly 2410 away from the
process cell 420. The movement of the head assembly 2410 provides
the spacing required to remove and/or replace the substrate from
the electroplating process cell 240. When the cantilever arm
actuator 2457 is extended, the cantilever arm 2456 moves the head
assembly 2410 toward the process cell 420 to position the substrate
in the head assembly 2410 in a processing position.
[0101] The rotatable head assembly 2410 includes a rotating
actuator 2464 slideably connected to the mounting slide 2460. The
shaft 2468 of the head lift actuator 2458 is inserted through a
lift guide 2466 attached to the body of the rotating actuator 2464.
Preferably, the shaft 2468 is a lead-screw type shaft that moves
the lift guide (as indicated by arrows A3) between various vertical
positions. The rotating actuator 2464 is connected to the substrate
holder assembly 2450 through the shaft 2470 and rotates the
substrate holder assembly 2450 (as indicated by arrows A4). The
substrate holder assembly 2450 includes a bladder assembly, such as
the embodiments described above with respect to FIGS. 12-15 and 19,
and a cathode contact ring, such as the embodiments described above
with respect to FIGS. 7-10 and 18.
[0102] The rotation of the substrate during the electroplating
process generally enhances the deposition results. Preferably, the
head assembly is rotated between about 2 rpm and about 200 rpm
(preferably between about 20 and 40 rpm), during the electroplating
process. The substrate holder assembly 2472 can be rotated to
impart rotation to the substrate as the substrate holder device 14
lowers the seed layer on the substrate into contact with the
electrolyte solution in the process cell. The head assembly is
raised to remove the seed layer on the substrate from the
electrolyte solution in the process cell. The head assembly is
preferably rotated at a high speed (i.e., between about 100 and
about 2500 rpm) after the head assembly is lifted from the process
cell to enhance removal of residual electrolyte solution from the
head assembly by inertial force.
[0103] In one embodiment, the uniformity of the deposited film has
been improved within about 2% (i.e., maximum deviation of deposited
film thickness is at about 2% of the average film thickness) while
standard electroplating processes typically achieves uniformity at
best within about 5.5%. However, rotation of the head assembly is
not necessary to achieve uniform electroplating deposition in some
instances, particularly where the uniformity of electroplating
deposition is achieved by adjusting the processing parameters, such
as the chemicals in the electrolyte solution, electrolyte solution
flow and other parameters.
[0104] Referring back to FIG. 6, a cross sectional view of an
electroplating process cell 400, the substrate holder assembly 450
is positioned above the process cell 420. The process cell 420
generally comprises a bowl 430, a container body 472, an anode
assembly 474 and a filter 476. Preferably, the anode assembly 474
is disposed below the container body 472 and attached to a lower
portion of the container body 472, and the filter 476 is disposed
between the anode assembly 474 and the container body 472. The
container body 472 is preferably a cylindrical body comprised of an
electrically insulative material, such as ceramics, plastics,
PLEXIGLAS.RTM. (acrylic), lexane, PVC, CPVC, and PVDF.
Alternatively, the container body 472 can be made from a coated
metal, such as stainless steel, nickel and titanium. The coated
metal is coated with an insulating layer (such as TEFLON.RTM. [a
trademark of the E. l. duPont de Nemoirs Company of Wilmington,
Del.], PVDF, plastic, rubber and other combinations of materials)
that do not dissolve in the electrolyte solution. The insulating
layer can be electrically insulated from the electrodes (i.e., the
anode and cathode of the electroplating system). The container body
472 is preferably sized and adapted to conform to the substrate
plating surface and the shape of a substrate being processed
through the system, typically circular or rectangular in shape. One
preferred embodiment of the container body 472 comprises a
cylindrical ceramic tube having an inner diameter that has about
the same dimension as or slightly larger than the substrate
diameter. The inventors have discovered that the rotational
movement typically required in typical electroplating systems is
not required to achieve uniform plating results when the size of
the container body conforms to about the size of the substrate
plating surface.
[0105] An upper portion of the container body 472 extends radially
outwardly to form an annular weir 478. The weir 478 extends over
the inner wall 446 of the electrolyte solution collector 440 and
allows the electrolyte solution to flow into the electrolyte
solution collector 440. The upper surface of the weir 478
preferably matches the lower surface of the electric contact
element 466. Preferably, the upper surface of the weir 478 includes
an inner annular flat portion 480, a middle inclined portion 482
and an outer declined portion 484. When a substrate is positioned
in the processing position, the substrate plating surface is
positioned above the cylindrical opening of the container body 472.
A gap for electrolyte solution flow is formed between the lower
surface of the electric contact element 466 and the upper surface
of the weir 478. The lower surface of the electric contact element
466 is disposed above the inner flat portion 480 and the middle
inclined portion of the weir 478. The outer declined portion 484 is
sloped downwardly to facilitate flow of the electrolyte solution
into the electrolyte solution collector 440.
[0106] A lower portion of the container body 472 extends radially
outwardly to form a lower annular flange 486 for securing the
container body 472 to the bowl 430. The outer dimension (i.e.,
circumference) of the annular flange 486 is smaller than the
dimensions of the opening 444 and the inner circumference of the
electrolyte solution collector 440. The smaller dimension of the
annular flange to allow removal and replacement of the process cell
420 from the electroplating process cell 400. Preferably, multiple
bolts 488 are fixedly disposed on the annular flange 486 and extend
downwardly through matching bolt holes on the bowl 430. A plurality
of removable fastener nuts 490 secure the process cell 420 onto the
bowl 430. A seal 487, such as an elastomer O-ring, is disposed
between container body 472 and the bowl 430 radially inwardly from
the bolts 488 to prevent leaks from the process cell 420. The
nuts/bolts combination facilitates fast and easy removal and
replacement of the components of the process cell 420 during
maintenance.
[0107] Preferably, the filter 476 is attached to and completely
covers the lower opening of the container body 472, and the anode
assembly 474 is disposed below the filter 476. A spacer 492 is
disposed between the filter 476 and the anode assembly 474.
Preferably, the filter 476, the spacer 492, and the anode assembly
474 are fastened to a lower surface of the container body 472 using
removable fasteners, such as screws and/or bolts. Alternatively,
the filter 476, the spacer 492, and the anode assembly 474 are
removably secured to the bowl 430.
[0108] The anode assembly 474 preferably comprises a consumable
anode that serves as a metal source in the electrolyte solution.
Alternatively, the anode assembly 474 comprises a non-consumable
anode, and the metal to be electroplated is supplied within the
electrolyte solution from the electrolyte solution replenishing
system 220. As shown in FIG. 6, the anode assembly 474 is a
self-enclosed module having a porous anode enclosure 494 preferably
made of the same metal as the metal to be electroplated, such as
copper. Alternatively, the anode enclosure 494 is made of porous
materials, such as ceramics or polymeric membranes. A soluble metal
496, such as high purity copper for electrochemical plating of
copper, is disposed within the anode enclosure 494. The soluble
metal 496 preferably comprises metal particles, wires or a
perforated sheet. The porous anode enclosure 494 also acts as a
filter that keeps the particulates generated by the dissolving
metal within the anode enclosure 494. As compared to a
non-consumable anode, the consumable (i.e., soluble) anode provides
gas-generation-free electrolyte solution and minimizes the need to
constantly replenish the metal in the electrolyte solution.
[0109] An anode electrode contact 498 is inserted through the anode
enclosure 494 to provide electrical connection to the soluble metal
496 from a power supply. Preferably, the anode electrode contact
498 is made from a conductive material that is insoluble in the
electrolyte solution, such as titanium, platinum and
platinum-coated stainless steel. The anode electrode contact 498
extends through the bowl 430 and is connected to an electrical
power supply. Preferably, the anode electrical contact 498 includes
a threaded portion 497 (for a fastener nut 499 to secure the anode
electrical contact 498 to the bowl 430), and a seal 495 (such as a
elastomer washer, is disposed between the fastener nut 499 and the
bowl 430 to prevent leaks from the process cell 420).
[0110] The bowl 430 generally comprises a cylindrical portion 502
and a bottom portion 504. An upper annular flange 506 extends
radially outwardly from the top of the cylindrical portion 502. The
upper annular flange 506 includes a plurality of holes 508 that
matches the number of bolts 488 from the lower annular flange 486
of the container body 472. Bolts 488 are inserted through the holes
508, and the fastener nuts 490 are fastened onto the bolts 488 that
secure the upper annular flange 506 of the bowl 430 to the lower
annular flange 486 of the container body 472. Preferably, the outer
dimension (i.e., circumference) of the upper annular flange 506 is
about the same as the outer dimension (i.e., circumference) of the
lower annular flange 486. Preferably, the lower surface of the
upper annular flange 506 of the bowl 430 rests on a support flange
of the mainframe 214 when the process cell 420 is positioned on the
mainframe 214.
[0111] The inner circumference of the cylindrical portion 502
accommodates the anode assembly 474 and the filter 476. Preferably,
the outer dimensions of the filter 476 and the anode assembly 474
are slightly smaller than the inner dimension of the cylindrical
portion 502. These relative dimensions force a substantial portion
of the electrolyte solution to flow through the anode assembly 474
first before flowing through the filter 476. The bottom portion 504
of the bowl 430 includes an electrolyte solution inlet 510 that
connects to an electrolyte solution supply line from the
electrolyte solution replenishing system 220. Preferably, the anode
assembly 474 is disposed about a middle portion of the cylindrical
portion 502 of the bowl 430. The anode assembly 474 is configured
to provide a gap for electrolyte solution flow between the anode
assembly 474 and the electrolyte solution inlet 510 on the bottom
portion 504.
[0112] The electrolyte solution inlet 510 and the electrolyte
solution supply line are preferably connected by a releasable
connector that facilitates easy removal and replacement of the
process cell 420. When the process cell 420 needs maintenance, the
electrolyte solution is drained from the process cell 420, and the
electrolyte solution flow in the electrolyte solution supply line
is discontinued and drained. The connector for the electrolyte
solution supply line is released from the electrolyte solution
inlet 510, and the electrical connection to the anode assembly 474
is also disconnected. The head assembly 410 is raised or rotated to
provide clearance for removal of the process cell 420. The process
cell 420 is then removed from the mainframe 214, and a new or
reconditioned process cell is replaced into the mainframe 214.
[0113] Alternatively, the bowl 430 can be secured onto the support
flange of the mainframe 214, and the container body 472 along with
the anode and the filter are removed for maintenance. In this case,
the nuts securing the anode assembly 474 and the container body 472
to the bowl 430 are removed to facilitate removal of the anode
assembly 474 and the container body 472. New or reconditioned anode
assembly 474 and container body 472 are then replaced into the
mainframe 214 and secured to the bowl 430.
[0114] FIG. 20 is a cross sectional view of one embodiment of an
encapsulated anode. The encapsulated anode 2000 includes a
permeable anode enclosure that filters or traps "anode sludge" or
particulates generated as the metal is dissolved from the anode
plate 2004. As shown in FIG. 20, the anode plate 2004 comprises a
solid piece of copper. Preferably, the anode plate 2004 is a high
purity, oxygen free copper, enclosed in a hydrophilic anode
encapsulation membrane 2002. The anode plate 2004 is secured and
supported by a plurality of electrical contacts or feed-throughs
2006 that extend through the bottom of the bowl 430. The electrical
contacts or feed-throughs 2006 extend through the anode
encapsulation membrane 2002 into the bottom surface of the anode
plate 2004. The flow of the electrolyte solution is indicated by
the arrows A from the electrolyte solution inlet 510 disposed at
the bottom of the bowl 430 through the gap between the anode and
the bowl sidewall. The electrolyte solution also flows through the
anode encapsulation membrane 2002 by permeation into and out of the
gap between the anode encapsulation membrane and the anode plate,
as indicated by the arrows B. Preferably, the anode encapsulation
membrane 2002 comprises a hydrophilic porous membrane, such as a
modified polyvinyllidene fluoride membrane, having porosity between
about 60% and 80%, more preferably about 70%, and pore sizes
between about 0.025 .mu.m and about 1 .mu.m, more preferably
between about 0.1 .mu.m and about 0.2 .mu.m. One example of a
hydrophilic porous membrane is the Durapore Hydrophilic Membrane,
available from Millipore Corporation, located in Bedford, Mass. As
the electrolyte solution flows through the encapsulation membrane,
anode sludge and particulates generated by the dissolving anode are
filtered or trapped by the encapsulation membrane. Thus, the
encapsulation membranes improve the purity of the electrolyte
solution during the electroplating process, and defect formations
on the substrate during the electroplating process caused by anode
sludge and other such particulates are significantly reduced.
[0115] FIG. 21 is a cross sectional view of another embodiment of
an encapsulated anode. The anode plate 2004 is secured and
supported on the electrical feed-throughs 2006. A top encapsulation
membrane 2008 and a bottom encapsulation membrane 2010, disposed
respectively above and below the anode plate 2004, are attached to
a membrane support ring 2012 that is disposed around the anode
plate 2004. The top and bottom encapsulation membranes 2008, 2010
comprise a material from the list above for encapsulation membrane
of the first embodiment of the encapsulated anode. The membrane
support ring 2012 preferably comprises a relatively rigid material
(as compared to the encapsulation membrane), such as plastic or
other polymers. A bypass fluid inlet 2014 is disposed through the
bottom of the bowl 430 and through the bottom encapsulation
membrane 2010 to introduce electrolyte solution into the gap
between the encapsulation membranes and the anode plate. A bypass
outlet 2016 is connected to the membrane support ring 2012 and
extends through the bowl 430 to facilitate flow of excess
electrolyte solution with the anode sludge or generated
particulates out of the encapsulated anode into a waste drain (not
shown).
[0116] Preferably, the flow of the electrolyte solution within the
bypass fluid inlet 2014 and the main electrolyte solution inlet 510
is individually controlled by the flow control valves 2020, 2022.
The individual flow control valves 2020, 2022 are respectively
placed along the fluid lines connected to the inlets. The fluid
pressure in the bypass fluid inlet 2014 is preferably maintained at
a higher pressure than the pressure in the main electrolyte
solution inlet 510. The flow of the electrolyte solution inside the
bowl 430 from the main electrolyte solution inlet 510 is indicated
by arrows A, and the flow of the electrolyte solution inside the
encapsulated anode 2000 is indicated by the arrows B. A portion of
the electrolyte solution introduced into the encapsulated anode
flows out of the encapsulated anode through the bypass outlet 2016.
By providing a dedicated bypass electrolyte solution supply into
the encapsulated anode, the anode sludge or particulates generated
from the dissolving anode is continually removed from the anode,
thereby improving the purity of the electrolyte solution during the
electroplating process.
[0117] FIG. 22 is a cross sectional view of another embodiment of
an encapsulated anode. This embodiment of an encapsulated anode
2000 includes an anode plate 2004, a plurality of electrical
feed-throughs 2006, a top and a bottom encapsulation membrane 2008,
2010, and a membrane support ring 2012. The anode plate 2004 is
secured and supported on a plurality of electrical feed-throughs
2006. The top and a bottom encapsulation membranes 2008, 2010 are
attached to a membrane support ring 2012. A bypass outlet 2016
connected to the membrane support ring 2012 and extending through
the bowl 430. This embodiment of an encapsulated anode preferably
comprises materials as described above for the first and second
embodiments of an encapsulated anode. The bottom encapsulation
membrane 2010 according to the third embodiment includes one or
more openings 2024 disposed substantially above the main
electrolyte solution inlet 510. The opening 2024 is adapted to
receive flow of electrolyte solution from the main electrolyte
solution inlet 510 and is preferably about the same size as the
internal circumference of the main electrolyte solution inlet 510.
The flow of the electrolyte solution from the main electrolyte
solution inlet 510 is indicated by the arrows A and the flow of the
electrolyte solution within the encapsulated anode is indicated by
the arrows B. A portion of the electrolyte solution flows out of
the encapsulated anode through the bypass outlet 2016, carrying a
portion of the anode sludge and particulates generated from anode
dissolution.
[0118] FIG. 23 is a cross sectional view of yet another embodiment
of an encapsulated anode. This embodiment of an encapsulated anode
includes an anode plate 2004, a plurality of electrical
feed-throughs 2006, a top and a bottom encapsulation membrane 2008,
2010, and a membrane support ring 2012. The encapsulated anode 2000
includes an anode plate 2002 that is secured and supported on a
plurality of electrical feed-throughs 2006. A top and a bottom
encapsulation membrane 2008, 2010 are attached to a membrane
support ring 2012. A bypass fluid inlet 2014 is disposed through
the bottom of the bowl 430 and through the bottom encapsulation
membrane 2010 to introduce electrolyte solution into the gap
between the encapsulation membranes and the anode plate.
Preferably, the flow of the electrolyte solution through the bypass
fluid inlet 2014 and the main electrolyte solution inlet 510 is
individually controlled by control valves 2020, 2022, respectively.
The flow of the electrolyte solution from the main electrolyte
solution inlet 510 is indicated by the arrows A. The flow of the
electrolyte solution through the encapsulated anode is indicated by
arrows B. For this embodiment, the anode sludge and particulates
generated by the dissolving anode plate are filtered and trapped by
the encapsulation membranes as the electrolyte solution passes
through the membrane.
[0119] FIG. 16 is a schematic diagram of an electrolyte solution
replenishing system 220. The electrolyte solution replenishing
system 220 provides the electrolyte solution to the electroplating
process cells for the electroplating process. The electrolyte
solution replenishing system 220 generally comprises a main
electrolyte solution tank 602, a dosing module 603, a filtration
module 605, a chemical analyzer module 616, and an electrolyte
solution waste disposal system 622 connected to the analyzing
module 616 by an electrolyte solution waste drain 620. One or more
controllers control the composition of the electrolyte solution in
the main tank 602 and the operation of the electrolyte solution
replenishing system 220. Preferably, the controllers are
independently operable but integrated with the controller 222 of
the system platform 200.
[0120] The main electrolyte solution tank 602 provides a reservoir
for electrolyte solution and includes an electrolyte solution
supply line 612 that is connected to each of the electroplating
process cells through one or more fluid pumps 608 and valves 607. A
heat exchanger 624 or a heater/chiller disposed in thermal
connection with the main tank 602 controls the temperature of the
electrolyte solution stored in the main tank 602. The heat
exchanger 624 is connected to and operated by the controller
610.
[0121] The dosing module 603 is connected to the main tank 602 by a
supply line and includes a plurality of source tanks 606, or feed
bottles, a plurality of valves 609, and a controller 611. The
source tanks 606 contain the chemicals needed for composing the
electrolyte solution and typically include a de-ionized water
source tank and copper sulfate (CuSO.sub.4) source tank for
composing the electrolyte solution. Other source tanks 606 may
contain hydrogen sulfate (H.sub.2SO.sub.4), hydrogen chloride (HCl)
and various additives such as glycol. Each source tank is
preferably color coded and fitted with a unique mating outlet
connector adapted to connect to a matching inlet connector in the
dosing module. By color coding the source tanks and fitting the
source tanks with unique connectors, errors caused by human
operators when exchanging or replacing the source tanks are
significantly reduced.
[0122] The de-ionized water source tank preferably also provides
de-ionized water to the system for cleaning the system during
maintenance. The valves 609 associated with each source tank 606
regulate the flow of chemicals to the main tank 602 and may be any
of numerous commercially available valves such as butterfly valves,
throttle valves and the like. Activation of the valves 609 is
accomplished by the controller 611 which is preferably connected to
the controller 222 to receive signals therefrom.
[0123] The electrolyte solution filtration module 605 includes a
plurality of filter tanks 604. An electrolyte solution return line
614 is connected between each of the process cells and one or more
filter tanks 604. The filter tanks 604 remove the undesired
contents in the used electrolyte solution before returning the
electrolyte solution to the main tank 602 for re-use. The main tank
602 is also connected to the filter tanks 604 to facilitate
re-circulation and filtration of the electrolyte solution in the
main tank 602. By re-circulating the electrolyte solution from the
main tank 602 through the filter tanks 604, the undesired contents
in the electrolyte solution are continuously removed by the filter
tanks 604 to maintain a consistent level of purity. Additionally,
re-circulating the electrolyte solution between the main tank 602
and the filtration module 605 allows the various chemicals in the
electrolyte solution to be thoroughly mixed.
[0124] The electrolyte solution replenishing system 220 also
includes a chemical analyzer module 616 that provides real-time
chemical analysis of the chemical composition of the electrolyte
solution. The analyzer module 616 is fluidly coupled to the main
tank 602 by a sample line 613 and to the waste disposal system 622
by an outlet line 621. The analyzer module 616 generally comprises
at least one analyzer and a controller to operate the analyzer. The
number of analyzers required for a particular processing tool
depends on the composition of the electrolyte solution. For
example, while a first analyzer may be used to monitor the
concentrations of organic substances, a second analyzer is needed
for inorganic chemicals. In the specific embodiment shown in FIG.
16 the chemical analyzer module 616 comprises an auto titration
analyzer 615 and a cyclic voltametric stripper (CVS) 617. Both
analyzers are commercially available from various suppliers. An
auto titration analyzer that may be used to advantage is available
from Parker Systems and a cyclic voltametric stripper is available
from ECI. The auto titration analyzer 615 determines the
concentrations of inorganic substances such as copper chloride and
acid. The CVS 617 determines the concentrations of organic
substances such as the various additives which may be used in the
electrolyte solution and by-products resulting from the processing
which are returned to the main tank 602 from the process cells.
[0125] The analyzer module shown in FIG. 16 is merely illustrative.
In another embodiment, each analyzer may be coupled to the main
electrolyte solution tank by a separate supply line and be operated
by separate controllers. Persons skilled in the art will recognize
other embodiments.
[0126] In operation, a sample of electrolyte solution is flowed to
the analyzer module 616 via the sample line 613. Although the
sample may be taken periodically, preferably a continuous flow of
electrolyte solution is maintained to the analyzer module 616. A
portion of the sample is delivered to the auto titration analyzer
615 and a portion is delivered to the CVS 617 for the appropriate
analysis. The controller 619 initiates command signals to operate
the analyzers 615, 617 in order to generate data. The information
from the chemical analyzers 615, 617 is then communicated to the
controller 222. The controller 222 processes the information and
transmits signals that include user-defined chemical dosage
parameters to the dosing controller 611. The received information
is used to provide real-time adjustments to the source chemical
replenishment rates by operating one or more of the valves 609. The
received information thereby maintains a desired, and preferably
constant, chemical composition of the electrolyte solution
throughout the electroplating process. The waste electrolyte
solution from the analyzer module is then flowed to the waste
disposal system 622 via the outlet line 621.
[0127] Although a preferred embodiment utilizes real-time
monitoring and adjustments of the electrolyte solution, various
alternatives may be employed. For example, the dosing module 603
may be controlled manually by an operator observing the output
values provided by the chemical analyzer module 616. Preferably,
the system software allows for both an automatic real-time
adjustment mode as well as an operator (manual) mode. Further,
although multiple controllers are shown in FIG. 16, a single
controller may be used to operate various components of the system
such as the chemical analyzer module 616, the dosing module 603,
and the heat exchanger 624. Other embodiments will be apparent to
those skilled in the art.
[0128] The electrolyte solution replenishing system 220 also
includes an electrolyte solution waste drain 620 connected to an
electrolyte solution waste disposal system 622 for safe disposal of
used electrolyte solutions, chemicals and other fluids used in the
electroplating system. Preferably, the electroplating cells include
a direct line connection to the electrolyte solution waste drain
620 (or the electrolyte solution waste disposal system 622). The
electrolyte solution waste drain 620 drains the electroplating
cells without returning the electrolyte solution through the
electrolyte solution replenishing system 220. The electrolyte
solution replenishing system 220 preferably also includes a bleed
off connection to bleed off excess electrolyte solution to the
electrolyte solution waste drain 620.
[0129] Preferably, the electrolyte solution replenishing system 220
also includes one or more degasser modules 630 adapted to remove
undesirable gases from the electrolyte solution. The degasser
module generally comprises a membrane that separates gases from the
fluid passing through the degasser module and a vacuum system for
removing the released gases. The degasser modules 630 are
preferably placed in line on the electrolyte solution supply line
612 adjacent to the process cells 240. The degasser modules 630 are
preferably positioned as close as possible to the process cells 240
so most of the gases from the electrolyte solution replenishing
system are removed by the degasser modules before the electrolyte
solution enters the process cells. Preferably, each degasser module
630 includes two outlets to supply degassed electrolyte solution to
the two process cells 240 of each processing station 218.
Alternatively, a degasser module 630 is provided for each process
cell. The degasser modules can be placed at many other alternative
positions. For example, the degasser module can be placed at other
positions in the electrolyte solution replenishing system, such as
along with the filter section or in a closed-loop system with the
main tank or with the process cell. As another example, one
degasser module is placed in line with the electrolyte solution
supply line 612 to provide degassed electrolyte solution to all of
the process cells 240 of the electro-chemical plating system.
Additionally, a separate degasser module is positioned in-line or
in a closed-loop with the de-ionized water supply line and is
dedicated for removing oxygen from the de-ionized water source.
Because de-ionized water is used to rinse the processed substrates,
free oxygen gases are preferable removed from the de-ionized water
before reaching the SRD modules so that the electroplated copper is
less likely to become oxidized by the rinsing process. Degasser
modules are well known in the art and commercial embodiments are
generally available and adaptable for use in a variety of
applications. A commercially available degasser module is available
from Millipore Corporation, located in Bedford, Mass.
[0130] One embodiment of the degasser module 630, as shown in FIG.
26a, includes a hydrophobic membrane 632 having a fluid (i.e.,
electrolyte solution) passage 634 on one side of the membrane 632.
A vacuum system 636 disposed on the opposite side of the membrane.
The enclosure 638 of the degasser module includes an inlet 640 and
one or more outlets 642. As the electrolyte solution passes through
the degasser module 630, the gases and other micro-bubbles in the
electrolyte solution are separated from the electrolyte solution
through the hydrophobic membrane and removed by the vacuum system.
Another embodiment of the degasser module 630', as shown in FIG.
26b, includes a tube of hydrophobic membrane 632' and a vacuum
system 636 disposed around the tube of hydrophobic membrane 632'.
The electrolyte solution is introduced inside the tube of
hydrophobic membrane, and as the electrolyte solution passes
through the fluid passage 634 in the tube. The hydrophobic membrane
separates gases and other micro-bubbles in the electrolyte
solution, and a tube that is connected to the vacuum system 636
removes the separated gasses. More complex designs of degasser
modules are contemplated, including designs having serpentine paths
of the electrolyte solution across the membrane and other
multi-sectioned designs of degasser modules.
[0131] Although not shown in FIG. 16, the electrolyte solution
replenishing system 220 may include a number of other components.
For example, the electrolyte solution replenishing system 220
preferably also includes one or more additional tanks for storage
of chemicals for a substrate cleaning system, such as the SRD
station. Double-contained piping for hazardous material connections
may also be employed to provide safe transport of the chemicals
throughout the system. Optionally, the electrolyte solution
replenishing system 220 includes connections to additional or
external electrolyte solution processing system to provide
additional electrolyte solution supplies to the electroplating
system.
[0132] FIG. 17 is a cross sectional view of one embodiment of rapid
thermal anneal (RTA) chamber. The RTA chamber 211 is preferably
connected to the loading station 210, and substrates are
transferred into and out of the RTA chamber 211 by the loading
station transfer robot 228. The electroplating system, as shown in
FIGS. 2 and 3, preferably comprises two RTA chambers 211 disposed
on opposing sides of the loading station 210, corresponding to the
symmetric design of the loading station 210. RTA chambers are
generally well known in the art, and RTA chambers are typically
utilized in substrate processing systems to enhance the properties
of the deposited materials. A variety of RTA chamber designs,
including hot plate designs and heat lamp designs, may be used to
enhance the electroplating results. One RTA chamber is the WxZ
chamber available from Applied Materials, Inc., located in Santa
Clara, Calif. Although the invention is described using a hot plate
RTA chamber, other types of RTA chambers may be used as well.
[0133] The RTA chamber 211 generally comprises an enclosure 902, a
heater plate 904, a heater 907 and a plurality of substrate support
pins 906. The enclosure 902 includes a base 908, a sidewall 910 and
a top 912. Preferably, a cold plate 913 is disposed below the top
912 of the enclosure. Alternatively, the cold plate is integrally
formed as part of the top 912 of the enclosure. Preferably, a
reflector insulator dish 914 is disposed inside the enclosure 902
on the base 908. The reflector insulator dish 914 is typically made
from a material such as quartz, alumina, or other material that can
withstand high temperatures (i.e., greater than about 500.degree.
C.). The reflector insulator dish acts as a thermal insulator
between the heater 907 and the enclosure 902. The dish 914 may also
be coated with a reflective material, such as gold, to direct heat
back to the heater plate 906.
[0134] The heater plate 904 preferably has a large mass compared to
the substrate being processed in the system. The heater plate is
preferably fabricated from a material such as silicon carbide,
quartz, or other materials that do not react with any ambient gases
in the RTA chamber 211 or with the. substrate material. The heater
907 typically comprises a resistive heating element or a
conductive/radiant heat source and is disposed between the heated
plate 906 and the reflector insulator dish 914. The heater 907 is
connected to a power source 916 which supplies the energy needed to
heat the heater 907. Preferably, a thermocouple 920 is disposed in
a conduit 922, disposed through the base 908 and dish 914, and
extends into the heater plate 904. The thermocouple 920 is
connected to the controller 222 and supplies temperature
measurements to the controller. The controller 222 then increases
or decreases the heat supplied by the heater 907 according to the
temperature measurements and the desired anneal temperature.
[0135] The enclosure 902 preferably includes a cooling member 918
disposed outside of the enclosure 902 in thermal contact with the
sidewall 910 to cool the enclosure 902. Alternatively, one or more
cooling channels (not shown) are formed within the sidewall 910 to
control the temperature of the enclosure 902. The cold plate 913
disposed on the inside surface of the top 912 cools a substrate
that is positioned in close proximity to the cold plate 913.
[0136] The RTA chamber 211 includes a slit valve 922 disposed on
the sidewall 910 of the enclosure 902 for facilitating transfers of
substrates into and out of the RTA chamber. The slit valve 922
selectively seals an opening 924 on the sidewall 910 of the
enclosure that communicates with the loading station 210. The
loading station transfer robot 228 (see FIG. 2) transfers
substrates into and out of the RTA chamber through the opening
924.
[0137] The substrate support pins 906 preferably comprise distally
tapered members constructed from quartz, aluminum oxide, silicon
carbide, or other high temperature resistant materials. Each
substrate support pin 906 is disposed within a tubular conduit 926,
preferably made of a heat and oxidation resistant material, that
extends through the heater plate 904. The substrate support pins
906 are connected to a lift plate 928 for moving the substrate
support pins 906 in a uniform manner. The lift plate 928 is
attached to an actuator 930 (such as a stepper motor) through a
lift shaft 932. The actuator 930 moves the lift plate 928 to
facilitate positioning of a substrate at various vertical positions
within the RTA chamber. The lift shaft 932 extends through the base
908 of the enclosure 902 and is sealed by a sealing flange 934
disposed around the shaft.
[0138] To transfer a substrate into the RTA chamber 211, the slit
valve 922 is opened, and the loading station transfer robot 228
extends its robot blade having a substrate positioned thereon
through the opening 924 into the RTA chamber. The robot blade of
the loading station transfer robot 228 positions the substrate in
the RTA chamber above the heater plate 904, and the substrate
support pins 906 are extended upwards to lift the substrate above
the robot blade. The robot blade then retracts out of the RTA
chamber, and the slit valve 922 closes the opening. The substrate
support pins 906 are then retracted to lower the substrate to a
desired distance from the heater plate 904. Optionally, the
substrate support pins 906 may retract fully to place the substrate
in direct contact with the heater plate.
[0139] Preferably, a gas inlet 936 is disposed through the sidewall
910 of the enclosure 902 to allow selected gas flow into the RTA
chamber 211 during the anneal treatment process. The gas inlet 936
is connected to a gas source 938 through a valve 940 for
controlling the flow of the gas into the RTA chamber 211. A gas
outlet 942 is preferably disposed at a lower portion of the
sidewall 910 of the enclosure 902 to exhaust the gases in the RTA
chamber. The gas outlet is preferably connected to a relief/check
valve 944 to prevent backstreaming of atmosphere from outside of
the chamber. Optionally, the gas outlet 942 is connected to a
vacuum pump (not shown) to exhaust the RTA chamber to a desired
vacuum level during an anneal treatment.
[0140] A substrate is annealed in the RTA chamber 211 after the
substrate has been electroplated in the electroplating cell and
cleaned in the SRD station. Preferably, the RTA chamber 211 is
maintained at about atmospheric pressure, and the oxygen content
inside the RTA chamber 211 is controlled to less than about 100 ppm
during the anneal treatment process. Preferably, the ambient
environment inside the RTA chamber 211 comprises nitrogen (N.sub.2)
or a combination of nitrogen (N.sub.2) and less than about 4%
hydrogen (H.sub.2). The ambient gas flow into the RTA chamber 211
is maintained at greater than 20 liters/min to control the oxygen
content to less than 100 ppm. The electroplated substrate is
preferably annealed at a temperature between about 200.degree. C.
and about 450.degree. C. for between about 30 seconds and 30
minutes (and more preferably, between about 250.degree. C and about
400.degree. C. for between about 1 minute and 5 minutes). RTA
processing typically requires a temperature increase of at least
50.degree. C. per second. To provide the required rate of
temperature increase for the substrate during the anneal treatment,
the heater plate is preferably maintained at between about
350.degree. C., and 450.degree. C. The substrate is preferably
positioned at between about 0 mm and about 20 mm from the heater
plate (i.e., contacting the heater plate) for the duration of the
anneal treatment process. Preferably, a controller 222 controls the
operation of the RTA chamber 211, including maintaining the desired
ambient environment in the RTA chamber and the temperature of the
heater plate.
[0141] After the anneal treatment process is completed, the
substrate support pins 906 lift the substrate to a position for
transfer out of the RTA chamber 211. The slit valve 922 is opened,
and the robot blade of the loading station transfer robot 228 is
extended into the RTA chamber and positioned below the substrate.
The substrate support pins 906 retract to lower the substrate onto
the robot blade, and the robot blade then retracts out of the RTA
chamber. The loading station transfer robot 228 then transfers the
processed substrate into the cassette 232 for removal out of the
electroplating processing system. (see FIGS. 2 and 3).
[0142] Referring back to FIG. 2, the system platform 200 includes a
controller 222 that controls the functions of each component of the
platform. Preferably, the controller 222 is mounted above the
mainframe 214, and the controller comprises a programmable
microprocessor. The programmable microprocessor is typically
programmed using software designed specifically for controlling all
components of the system platform 200. The controller 222 also
provides electrical power to the components of the system and
includes a control panel 223 that allows an operator to monitor and
operate the system platform 200. The control panel 223, as shown in
FIG. 2, is a stand-alone module that is connected to the controller
222 through a cable and provides easy access to an operator.
Generally, the controller 222 coordinates the operations of the
loading station 210, the RTA chamber 211, the SRD station 212, the
mainframe 214 and the processing stations 218. Additionally, the
controller 222 coordinates with the controller of the electrolyte
solution replenishing system 220 to provide the electrolyte
solution for the electroplating process.
[0143] The following is a description of a typical substrate
electroplating process sequence through the system platform 200 as
shown in FIG. 2. A substrate cassette containing a plurality of
substrates is loaded into the substrate cassette receiving areas
224 in the loading station 210 of the system platform 200. A
loading station transfer robot 228 picks up a substrate from a
substrate slot in the substrate cassette and places the substrate
in the substrate orientor 230. The substrate orientor 230
determines and orients the substrate to a desired orientation for
processing through the system. The loading station transfer robot
228 then transfers the oriented substrate from the substrate
orientor 230 and positions the substrate in one of the substrate
slots in the substrate pass-through cassette 238 in the SRD station
212. The mainframe transfer robot 242 picks up the substrate from
the substrate pass-through cassette 238 and positions the substrate
for transfer by the flipper robot 248. The flipper robot 248
rotates its robot blade below the substrate and picks up substrate
from mainframe transfer robot blade. The vacuum suction gripper on
the flipper robot blade secures the substrate on the flipper robot
blade, and the flipper robot flips the substrate from a face up
position to a face down position. The flipper robot 248 rotates and
positions the substrate face down in the substrate holder assembly
450. The substrate is positioned below the substrate holder 464 but
above the electric contact element 466. The flipper robot 248 then
releases the substrate to position the substrate into the electric
contact element 466. The substrate holder 464 moves toward the
substrate and the vacuum chuck secures the substrate on the
substrate holder 464. The bladder assembly 470 on the substrate
holder assembly 450 exerts pressure against the substrate backside
to ensure electrical contact between the substrate plating surface
and the electric contact element 466.
[0144] The head assembly 452 is lowered to a processing position
above the process cell 420. At this position the substrate is below
the upper plane of the weir 478 and contacts the electrolyte
solution contained in the process cell 420. The power supply is
activated to supply electrical power (i.e., voltage and current) to
the cathode and the anode to enable the electroplating process. The
electrolyte solution is typically continually pumped into the
process cell during the electroplating process. The electrical
power supplied to the cathode and the anode and the flow of the
electrolyte solution are controlled by the controller 222 to
achieve the desired electroplating results. Preferably, the head
assembly is rotated as the head assembly is lowered and also during
the electroplating process.
[0145] After the electroplating process is completed, the head
assembly 410 raises the substrate holder assembly and removes the
substrate from the electrolyte solution. Preferably, the head
assembly is rotated for a period of time to enhance removal of
residual electrolyte solution from the substrate holder assembly.
The vacuum chuck and the bladder assembly of the substrate holder
then release the substrate from the substrate holder. The substrate
holder is raised to allow the flipper robot blade to pick up the
processed substrate from the cathode contact ring. The flipper
robot rotates the flipper robot blade above the backside of the
processed substrate in the cathode contact ring and picks up the
substrate using the vacuum suction gripper on the flipper robot
blade. The flipper robot rotates the flipper robot blade with the
substrate out of the substrate holder assembly, flips the substrate
from a face-down position to a face-up position, and positions the
substrate on the mainframe transfer robot blade. The mainframe
transfer robot then transfers and positions the processed substrate
above the SRD module 236. The SRD substrate support lifts the
substrate, and the mainframe transfer robot blade retracts away
from the SRD module 236. The substrate is cleaned in the SRD module
using deionized water or a combination of de-ionized water and a
cleaning fluid as described in detail above. The substrate is then
positioned for transfer out of the SRD module. The loading station
transfer robot 228 picks up the substrate from the SRD module 236
and transfers the processed substrate into the RTA chamber 211 for
an anneal treatment process to enhance the properties of the
deposited materials. The annealed substrate is then transferred out
of the RTA chamber 211 by the loading station robot 228 and placed
back into the substrate cassette for removal from the
electroplating system. The above-described sequence can be carried
out for a plurality of substrates substantially simultaneously in
the system platform 200. Also, the electroplating system can be
adapted to provide multi-stack substrate processing.
[0146] Wet Process Operations
[0147] The above system platform 200 is configured to process
multiple substrates using the loading station transfer robots 228
and a mainframe transfer robot 242. The different robots, cells, or
devices in the system platform can be broken down into wet or dry
robots, cells, or devices. During processing, the dry robots,
cells, or devices do not contact the fluids, crystals, chemicals,
etc. associated with the wet processes. The dry robots, cells, or
devices are maintained cleaner, and free from the impurities,
associated with the wet areas. Multiple embodiments of system
platforms 200 bifurcated into wet and dry areas are detailed. The
fountain plater shown in FIG. 1 may be integrated into one
embodiment of a wet area in a system platform.
[0148] A wet area 282 and a dry area 280 are depicted in the
embodiment of the system platform 200 shown in FIG. 3. Processing
of the substrate is performed in the wet robots, cells, or devices.
The substrate is introduced into, or removed from, the dry robots,
cells, or devices of the system platform. The substrates in the
loading station are dry (contain no crystals or chemicals such as
copper sulfate) to limit the passage of chemicals associated with
the transfer of the substrate to different process cells.
Additionally, "dry" substrates that are not coated with copper
sulfate crystals do not have the surface irregularities associated
with the crystals. It is more difficult for a vacuum plate of a
robot device to form a seal with substrates that have the surface
coarseness associated with crystalline coating since air can leak
between the course surface provided by the crystalline surface. The
substrate being dry and clean from impurities makes further
processing on the substrate easier. The robot transfer and
processing steps and equipment associated with cleaning the
crystals from the substrate can be limited.
[0149] As indicated in the embodiment of FIG. 3, the dry areas 280
comprises the components of the loading station 210 (the thermal
anneal chambers 211, the cassette receiving areas 224, the
substrate orientor 230, and the substrate cassette 232). The wet
areas 282 comprises the SRD station 211, including the SRD modules
236, the IBC system 235, and the in-stations 238, the mainframe
214, including the processing station, and the electrolyte solution
replenishing system 220. The wet area contains those locations
within the system platform 200 where liquids and chemical crystals
that are contained in electrolyte solution may be present. Due to
typical processing operations, it is desired to keep substrates
within the wet areas 282 as dry and free from crystals as
practical. However, a certain amount of liquids and crystals from
the processes and stations within the wet areas 282 will transfer
to other processes, stations, and robots within the wet area during
transfer and processing operations. Therefore, wet areas 282 have
to be cleaned frequently to limit a build-up from the residue from
the liquids and crystals used within the wet areas.
[0150] By comparison, the SRD module 236 and the IBC system 235
performs a more thorough rinsing, using for example de-ionized
water or an etchant, than possible within the processing stations
218 in general. In general, the SRD station removes unwanted
deposits at certain locations such as the backside of the
substrate, as well as rinsing the entire surface of the substrate
with de-ionized water. In the SRD module 236, the substrate is
rotated at a high angular velocity (often thousands of RPMs) with a
rinse liquid being directed at the surface of the substrate such
that liquids or crystals on the substrate are removed by rinsing
and centrifugal force. In the IBC system 235, unwanted deposits and
crystals are removed from surfaces of the substrates such as the
beveled edges. In the IBC system, de-ionized water is applied to
the surface of the substrate and the substrate is spun at
relatively high angular velocities (for example, often thousands of
RPMs). Liquids on the surface of the substrate are removed by the
spinning action of the substrate within the IBC system 235.
[0151] The SRD module 236 and the IBC system 235 can therefore
interact to remove any liquids on the surface of the substrates. In
addition, the SRD module 236 and/or the IBC system 235 can be used
to remove unwanted deposits and crystals from the surface of the
substrate. As such, undesired liquids, deposits, and crystals (such
a copper sulfate crystals) that remain on the surface of the
substrate after processing within the processing stations 218 can
be removed within the SRD station 212 of the system platform 200.
As such, it is entirely possible to deliver any wafer from the wet
area 282 to the dry area 280 in a condition that is dry, clean, and
free of unwanted chemicals, deposits, and crystals. A wafer that is
dry and clean is in the condition where it can be quickly
transferred to another process cell or cluster tool to perform
further desired processing, or as a finished product. In brief, a
dry and clean wafer can be transferred to the dry area 280 for
further processing without fear of transfer of chemicals, crystals
and deposits.
[0152] The use of wet and dry areas (that contain respective wet
and dry robots and respective wet and dry cells) in system platform
200 may be performed in electroplating systems, or systems that
perform any other known wet process. For example, electroless
processes and chemical mechanical polishing (CMP), processes may
both be considered "wet" processes. Electroless systems involve
volatile chemicals contained in an electroless bath. One example of
a CMP process is shown and described in U.S. Pat. No. 5,234,867,
ENTITLED "METHOD FOR PLANARIZING SEMICONDUCTOR WAFERS WITH A
NON-CIRCULAR POLISHING PAD", to Schultz (incorporated herein by
reference). One example of an electroless system is provided in
U.S. patent application Ser. No. 09/350877, entitled "IN-SITU
ELECTROLESS COPPER SEED LAYER ENHANCEMENT IN AN ELECTROPLATING
SYSTEM" to Cheung et al. (incorporated herein by reference). When
the substrates are immersed into the electroless bath, metals
contained in the electroless bath are deposited on a surface of the
substrate. Systems that use electroless systems or CMP systems
could also be segmented into wet and dry areas. For example, in the
above disclosure, CMP cells or electroless cells could be provided
in place of the electroplating process cells 240 shown in FIGS. 2
and 3.
[0153] FIG. 27 shows one embodiment of a method 2700 to be
performed by the controller 222 to control the operation of the
mainframe transfer robot 242 and the loading station transfer robot
242. The method 2700 should be read in conjunction with FIGS. 2 and
3. In this disclosure, the mainframe transfer robot 242 is
considered a "wet" robot since it receives substrates that have
been processed. By comparison, the loading station transfer robot
228 is considered a "dry" robot since the substrates that it
handles are dry prior top processing, or have been dried following
processing. The processed substrates are sent through the SRD
module before they encounter the loading station transfer robot
228. Therefore, the substrates that the loading station transfer
robot encounters are "dry".
[0154] The method 2700 starts with block 2702 in which the dry
robot 228 drops a substrate into the in-station 238. The dry robot
originally receives the substrate from one of the cassette
receiving areas 224. The method 2700 continues to block 2704 in
which the wet robot 242 picks up the substrate from the in-station.
The method continues to block 2706 in which the wet robot 242
transfers the substrate to the process cell 240 to process the
substrate. During block 2706, the processing of the substrate may
involve the wet robot 242 alternatively transferring the substrate
between the process cell 240, the SRD module 236, and/or the IBC
station 235. The process cell deposits another layer of metal film
on the seed layer on the substrate and the IBC station 235.
Unwanted deposits are removed from the surface of the substrate in
the SRD module 236 or the IBC station.
[0155] After the final layer of metal film is deposited in the
process cell 240, the method 2700 continues to block 2708 in which
the wet robot 242 transfers the substrate to the IBC system 235.
While the substrates are in the IBC system 235, the unwanted
deposits are removed from the surface of the substrate. The surface
of the substrates are then rinsed with de-ionized water. The method
2700 continues to block 2712 in which the (wet) substrates are
transferred by the wet robot 242 to the appropriate SRD module 236.
While the substrates are in the SRD module, the substrates are spun
with an etchant applied to unwanted deposits to etch the unwanted
deposits. De-ionized water is then applied to the substrate to
rinse the etchant and the etched deposited material from the
surface of the substrate. The substrate is then spun at a
relatively high angular velocity (typically in the thousands of
rotations per minute). The spinning of the substrate is sufficient
to remove any residual liquid (etchant, electrolyte solution, or
de-ionized water) from the surface of the substrate. Following the
spinning of the substrate in the SRD module 236, the substrate is
dry and can be handled as being dry. The dry substrate will not
contact further robots and cells that encounter the substrate.
[0156] The method 2700 continues to block 2716 in which the clean
robot 228 picks up the dry substrate from the SRD module and
handles the substrate as desired. Typically, the dry substrates are
transferred to the substrate cassette receiving areas 224. One or
more substrates can be picked up from the substrate cassette
receiving areas 224 using known techniques.
[0157] The method 2700 thereby provides a technique by which
substrates are transferred within wet areas 282 or dry areas 280
separated by a separation line 284. The surface of the substrates
contained within the wet areas 282 may be (and typically are) wet
from electrolyte solution, etchant, and/or de-ionized water, etc.
The wet robot 242 is configured to handle wet substrates, and the
wet robot should be cleaned frequently. The surface of the
substrates within the dry area 280 is typically maintained "dry"
and free of crystals, chemicals, and deposits. The dry robot 228 is
configured to handle dry substrates, and the dry robot does not
have to cleaned or dried nearly as frequently as the wet robot 242
of the impurities contained in the wet robot. Segmenting the
electroplating system platform 200 into "wet" and "dry" areas
limits those areas (the wet areas) that have to be cleaned more
frequently to limit passage of fluids, chemicals, deposits, and/or
crystals to the robots, cells, and processing equipment.
[0158] While the foregoing is directed to the preferred embodiment
of the present invention, other and further embodiments of the
invention may be devised without departing from the basic scope
thereof.
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