U.S. patent application number 10/630185 was filed with the patent office on 2004-02-05 for electro-chemical deposition cell for face-up processing of single semiconductor substrates.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Denome, Mark, Dordi, Yezdi, Edwards, Roy, Lowrance, Robert B., Stevens, Joe, Sugarman, Michael.
Application Number | 20040020781 10/630185 |
Document ID | / |
Family ID | 22171573 |
Filed Date | 2004-02-05 |
United States Patent
Application |
20040020781 |
Kind Code |
A1 |
Dordi, Yezdi ; et
al. |
February 5, 2004 |
Electro-chemical deposition cell for face-up processing of single
semiconductor substrates
Abstract
An apparatus and method for electro-chemically depositing a
uniform metal layer onto a substrate is provided. In one aspect,
the apparatus includes a cathode connected to the substrate plating
surface, an anode disposed above the substrate support member and
an electroplating solution inlet supplying an electroplating
solution fluidly connecting the anode and the substrate plating
surface. In another aspect, the apparatus further includes a dual
catch-cup system having an electroplating solution catch-cup and a
rinse catch-cup. The dual catch-cup system provides separation of
the electroplating solution and the rinse solutions during
processing and provides re-circulating systems for the different
solutions of the electroplating system.
Inventors: |
Dordi, Yezdi; (Palo Alto,
CA) ; Stevens, Joe; (San Jose, CA) ; Edwards,
Roy; (Los Gatos, CA) ; Lowrance, Robert B.;
(Los Gatos, CA) ; Sugarman, Michael; (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: |
22171573 |
Appl. No.: |
10/630185 |
Filed: |
July 29, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10630185 |
Jul 29, 2003 |
|
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10178469 |
Jun 24, 2002 |
|
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6599402 |
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10178469 |
Jun 24, 2002 |
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09294240 |
Apr 19, 1999 |
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6416647 |
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60082494 |
Apr 21, 1998 |
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Current U.S.
Class: |
205/143 ;
205/148 |
Current CPC
Class: |
C25D 17/001 20130101;
C25D 17/004 20130101; H01L 21/67051 20130101; H01L 21/68742
20130101; C25D 7/123 20130101; C25D 5/20 20130101; C25D 21/18
20130101; H01L 21/6715 20130101; H01L 21/6838 20130101; C25D 17/005
20130101; C25D 17/08 20130101; H01L 21/68792 20130101; C25D 21/00
20130101; H01L 21/68721 20130101 |
Class at
Publication: |
205/143 ;
205/148 |
International
Class: |
C25D 017/16; C25D
005/00 |
Claims
1. A method for electroplating a metal onto a substrate plating
surface, comprising: holding a substrate with the substrate plating
surface face-up on a rotatable substrate support member having
means for holding and rotating the substrate during an
electroplating process; positioning an anode above the substrate
plating surface; flowing an electroplating solution between the
anode and the substrate plating surface; and applying a plating
bias between the substrate plating surface and the anode to
electroplate the metal onto the plating surface.
2. The method of claim 1 wherein the step of holding the substrate
comprises providing a vacuum suction between the substrate support
member and a back side of the substrate.
3. The method of claim 1, wherein the step of holding the substrate
further comprises providing a peripheral seal between the substrate
support member and a back side of the substrate.
4. The method of claim 1, wherein applying a plating bias comprises
positioning a cathode contact ring in electrical contact with the
plating surface, the cathode contact ring defining a fluid
processing volume between the ring and the substrate surface.
5. The method of claim 4, wherein the cathode contact ring contacts
the plating surface annular ring and a plurality of contact pins
extending radially inwardly therefrom, and positioning an annular
seal radially inward of the contact pins.
6. The method of claim 1, wherein the electroplating solution flows
through perforations in the anode.
7. The method of claim 1, wherein the anode is consumed during the
operation of the electroplating method.
8. The method of claim 1, further comprising rotating the substrate
while flowing the electroplating solution between the anode and the
substrate plating surface.
9. The method of claim 1, further comprising vibrating the
substrate while flowing the electroplating solution between the
anode and the substrate plating surface.
10. The method of claim 4, wherein flowing the electroplating
solution further comprises filling the fluid processing volume.
11. The method of claim 10, wherein the positioning the anode
further comprises positioning the anode in electrical communication
with the fluid processing volume.
12. The method of claim 4, further comprising removing the cathode
contact ring and rinsing the substrate plating surface with a rinse
agent.
13. The method of claim 12, wherein the step of rinsing the
substrate plating surface comprises spraying a rinse agent over the
substrate plating surface while rotating the substrate support
within.
14. The method of claim 12, further comprising draining the rinse
agent back to a rinse agent reservoir.
15. The method of claim 12, further comprising purifying the rinse
agent in a purifier.
16. The method of claim 12, further comprising spin-drying the
substrate.
17. The method of claim 1, further comprising supplying the
electroplating solution into a cavity ring disposed above the
anode.
18. The method of claim 17, further comprising moving the cavity
ring while flowing the electroplating solution.
19. A method for electroplating a metal onto a substrate plating
surface, comprising: positioning the substrate plating surface
face-up on a support member; positioning the support member at a
first vertical position in a processing cell; electrically
contacting a cathode clamp ring to the substrate plating surface;
flowing an electroplating solution from an anode to the substrate
plating surface while rotating the substrate plating surface at the
first vertical position; positioning the support member at a second
vertical position in the cell, the second position being different
from the first position; and rinsing the substrate plating surface
with a rinse agent at the second vertical position.
20. The method of claim 19, further comprising spin-drying the
substrate plating surface.
21. The method of claim 19, further comprising draining the
electroplating solution to an electroplating solution
reservoir.
22. The method of claim 19, further comprising draining the rinse
agent to a rinse drain and purifying the rinse agent.
23. A method for plating and rinsing a substrate in a processing
cell, comprising: positioning the substrate face-up on a rotatable
substrate support member and positioning the substrate support
member at a plating position in the cell; electrically contacting a
plating surface of the substrate with a cathode electrode; forming
a fluid processing volume above the plating surface; positioning an
anode in electrical communication with the processing volume;
applying a plating bias between the anode and the cathode electrode
to plate a metal from the fluid processing volume onto the plating
surface in the plating position; moving the substrate support
member to a rinsing position; and dispensing a rinsing solution
onto the plating surface while rotating the substrate.
24. The method of claim 23, further comprising capturing a plating
solution used in the plating process with a first fluid receiving
member and capturing the rinsing solution with a second fluid
receiving member.
25. The method of claim 23, wherein electrically contacting the
plating surface comprises positioning a cathode contact ring having
a plurality of radially positioned substrate contact pins
positioned thereon such that the contact pins electrically engage a
perimeter of the substrate.
26. The method of claim 25, further comprising sealably engaging
the perimeter of the plating surface with an annular seal
positioned radially inward of the contact pins.
27. The method of claim 23, further comprising flowing an
electroplating solution through a plurality of perforations in the
anode to fill the fluid processing volume.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of co-pending U.S. patent
application Ser. No. 10/178,469, filed on Jun. 24, 2003, which
claims the benefit of U.S. patent application Ser. No. 09/294,240,
filed on Apr. 19, 1999, which claims the benefit of U.S.
Provisional Application Serial No. 60/082,494, filed on Apr. 21,
1998. Each of the aforementioned related patent applications are
incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to deposition of a
metal layer onto a substrate. More particularly, the present
invention relates to electroplating a metal layer onto a
substrate.
[0004] 2. Background of the Related Art
[0005] Sub-quarter micron multi-level metallization is one of the
key technologies for the next generation of ultra large scale
integration (ULSI). The multilevel interconnects that lie at the
heart of this technology require planarization of interconnect
features formed in high aspect ratio apertures, including contacts,
vias, lines and other features. Reliable formation of these
interconnect features is very important to the success of ULSI and
to the continued effort to increase circuit density and quality on
individual substrates and die.
[0006] As circuit densities increase, the widths of vias, contacts
and other features, as well as the dielectric materials between
them, decrease to less than 250 nanometers, whereas the thickness
of the dielectric layers remains substantially constant, with the
result that the aspect ratios for the features, i.e., their height
divided by width, increases. Many traditional deposition processes
have difficulty filling structures where the aspect ratio exceed
4:1, and particularly where it exceeds 10:1. Therefore, there is a
great amount of ongoing effort being directed at the formation of
void-free, nanometer-sized features having high aspect ratios
wherein the ratio of feature height to feature width can be 4:1 or
higher. Additionally, as the feature widths decrease, the device
current remains constant or increases, which results in an
increased current density in the feature.
[0007] Elemental aluminum (Al) and its alloys have been the
traditional metals used to form lines and plugs in semiconductor
processing because of aluminum's perceived low electrical
resistivity, its superior adhesion to silicon dioxide (SiO2), its
ease of patterning, and the ability to obtain it in a highly pure
form. However, aluminum has a higher electrical resistivity than
other more conductive metals such as copper, and aluminum also can
suffer from electromigration phenomena. Electromigration is
believed to be the motion of ions of a metal conductor in response
to the passage of high current through it, and it is a phenomenon
that occurs in a metal circuit while the circuit is in operation,
as opposed to a failure occurring during fabrication.
Electromigration can lead to the formation of voids in the
conductor. A void may accumulate and/or grow to a size where the
immediate cross-section of the conductor is insufficient to support
the quantity of current passing through the conductor, leading to
an open circuit. The area of conductor available to conduct heat
therealong likewise decreases where the void forms, increasing the
risk of conductor failure. This problem is sometimes overcome by
doping aluminum with copper and with tight texture or crystalline
structure control of the material. However, electromigration in
aluminum becomes increasingly problematic as the current density
increases.
[0008] Copper and its alloys have lower resistivities than aluminum
and significantly higher electromigration resistance as compared to
aluminum. These characteristics are important for supporting the
higher current densities experienced at high levels of integration
and increase device speed. Copper also has good thermal
conductivity and is available in a highly pure state. Therefore,
copper is becoming a choice metal for filling sub-quarter micron,
high aspect ratio interconnect features on semiconductor
substrates.
[0009] Despite the desirability of using copper for semiconductor
device fabrication, choices of fabrication methods for depositing
copper into very high aspect ratio features, such as a 10:1 aspect
ratio, 0.1 micron wide vias are limited. Precursors for CVD
deposition of copper are ill-developed, and physical vapor
deposition into such features produces unsatisfactory results
because of voids formed in the features.
[0010] As a result of these process limitations, plating which had
previously been limited to the fabrication of lines on circuit
boards, is just now being used to fill vias and contacts on
semiconductor devices. Metal electroplating in general is well
known in the art and can be achieved by a variety of techniques.
However, a number of obstacles impair consistent reliable
electroplating of copper onto semiconductor substrates having
nanometer-sized, high aspect ratio features. Generally, these
obstacles deal with providing uniform power distribution and
current density across the substrate plating surface to form a
metal layer having uniform thickness.
[0011] Present designs of cells for electroplating a metal on
semiconductor substrates are based on a fountain plater
configuration. FIG. 1 is a cross sectional view of a simplified
fountain plater. Generally, the fountain plater 10 includes an
electrolyte container 12 having a top opening, a substrate holder
14 disposed above the electrolyte container 12, an anode 16
disposed at a bottom portion of the electrolyte container 12 and a
cathode 20 contacting the substrate 18. The cathode 20 comprises a
plurality of contact pins distributed about the peripheral portion
of the substrate 18 to provide a bias about the perimeter of the
substrate. The contact pins generally provide a higher current
density near the contact points on the substrate surface, resulting
in a non-uniform deposition on the substrate surface. The
semiconductor substrate 18 is positioned a fixed distance above the
cylindrical electrolyte container 12, and the electrolyte impinges
perpendicularly on the substrate plating surface. Because of the
dispersion effects of the electrical current at the exposed edges
of the substrate 18 and the non-uniform flow of the electrolyte,
the fountain plater 10 provides non-uniform current distribution,
particularly at the region near the edges and at the center of the
substrate 18 that results in non-uniform plating of the metal. The
electrolyte flow uniformity at the center of the substrate 18 can
be improved by rotating the substrate 18. However, the plating
uniformity still deteriorates as the boundaries or edges of the
substrate are approached.
[0012] Furthermore, the fountain plater 10 presents additional
difficulties in substrate transfers because the substrate has to be
flipped for face-down plating. Generally, substrates are
transferred by robots having robot blades with a substrate
supporting surface, and the substrates are transferred with the
surface to be processed face-up. Preferably, the robot blade does
not contact the surface to be processed to eliminate risk of
damaging the substrate surface. Because the fountain plater 10
requires face-down processing, additional devices are required to
flip the substrate from a face-up transferring position to a
face-down processing position.
[0013] Therefore, there remains a need for a reliable, consistent
copper electroplating technique to deposit and form copper layers
on semiconductor substrates having nanometer-sized, high aspect
ratio features. There is also a need for a face-up electroplating
system that allows fast substrate processing and increases
throughput. Furthermore, there is a need for an apparatus for
delivering a uniform electrical power distribution to a substrate
surface and a need for an electroplating system that provides
uniform deposition on the substrate surface.
SUMMARY OF THE INVENTION
[0014] The invention generally provides an apparatus and a method
for electro-chemically depositing a uniform metal layer onto a
substrate. More specifically, the invention provides an
electro-chemical deposition cell for face-up processing of
semiconductor substrates comprising a substrate support member, a
cathode connected to the substrate plating surface, an anode
disposed above the substrate support member and an electroplating
solution inlet supplying an electroplating solution fluidly
connecting the anode and the substrate plating surface. Preferably,
the anode comprises a consumable metal source disposed in a liquid
permeable structure, and the anode and a cavity ring define a
cavity for holding and distributing the electroplating solution to
the substrate plating surface.
[0015] The invention also provides a substrate support member for
face-up electro-plating. Preferably, the substrate support member
comprises a vacuum chuck having vacuum ports disposed on the
substrate supporting surface that serves to provide suction during
processing and to provide a blow-off gas flow to prevent backside
contamination during substrate transfers. The substrate support
member also rotates and vibrates during processing to enhance the
electrodeposition onto the substrate plating surface.
[0016] Another aspect of the invention provides a dual catch-cup
system comprising an electroplating solution catch-cup and a rinse
catch-cup. The dual catch-cup system provides separation of the
electroplating solution and the rinse solutions during processing
and provides re-circulating systems for the different solutions of
the electroplating system.
[0017] The invention also provides an apparatus for delivering
electrical power to a substrate surface comprising an annular ring
electrically connected to a power supply, the annular ring having a
contact portion to electrically contact a peripheral portion of the
substrate surface. Preferably, the contact portion comprises
annular surface, such as a metal impregnated elastomer ring, to
provide continuous or substantially continuous electrical contact
with the peripheral portion of the substrate. The invention
provides a uniform distribution of power to a substrate deposition
surface by providing a uniform current density across the substrate
deposition surface through the continuous annular contact portion.
The invention also prevents process solution contamination of the
backside of the substrate by providing a seal between the contact
portion of the annular ring and the substrate deposition
surface.
[0018] Another aspect of the invention provides an apparatus for
holding a substrate for electro-chemical deposition comprising a
substrate holder having a substrate support surface and an annular
ring electrically connected to a power supply, the annular ring
having a contact portion to electrically contact a peripheral
portion of the substrate surface. The substrate holder is
preferably connected to one or more actuators that provide
rotational movement and/or vibrational agitation to the substrate
holder during processing to enhance deposition uniformity.
Preferably, the substrate holder comprises a vacuum chuck having a
substrate supporting surface, and an O-ring is disposed around a
substrate supporting surface to seal the backside of the substrate
from contamination by the processing solutions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] 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.
[0020] It is to be noted, however, that the appended drawings
illustrate only typical embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0021] FIG. 1 is a cross sectional view of a simplified fountain
plater.
[0022] FIG. 2 is a partial cut-away perspective view of an
electro-chemical deposition cell showing the interior components of
the electro-chemical deposition cell.
[0023] FIG. 3 is a cross sectional schematic view of an
electro-chemical deposition cell 200 showing a robot blade
transferring a substrate 202 into the electro-chemical deposition
cell 200.
[0024] FIG. 4 is a cross sectional schematic view of an
electro-chemical deposition cell 200 having a substrate 202
disposed on a substrate support member 204 in a processing position
according to the invention.
[0025] FIG. 5 is a cross sectional view of a substrate support
member 204 in a transferring position having a substrate disposed
on elevated lift pins.
[0026] FIG. 6 is a cross sectional view of an alternative
embodiment of the substrate support member 204 showing two separate
fluid conduits and dual level lip seals.
[0027] FIG. 7 is a bottom perspective view of a cathode clamp ring
having an alternative embodiment of the contact portion comprising
a plurality of contact pads.
[0028] FIG. 8 is a partial cross sectional schematic view of
another embodiment of a cathode clamp ring.
[0029] FIG. 9 is a cross sectional partial view of a cathode clamp
ring showing another embodiment of a contact portion of the clamp
ring.
[0030] FIG. 10 is a see-through perspective of a section of an
embodiment of a metal impregnated elastomer ring 350.
[0031] FIG. 11 is a top view of an electroplating solution catch
cup 246.
[0032] FIG. 12 is a cross sectional schematic view of an
electro-chemical deposition cell 200 showing one embodiment of the
anode/cavity ring assembly for drip control where a substrate
support member 204 is shown positioned in a rinsing position
according to the invention.
[0033] FIG. 13 is a top view of a shutter plate 238 positioned
above cathode clamp ring 210, showing an alternative solution for
controlling the dripping of residual electroplating solutions from
the anode/cavity ring assembly.
[0034] FIG. 14 is a side view of an electro-chemical deposition
cell having a sub-chamber for the anode/cavity ring assembly.
[0035] FIG. 15 is a bottom view of an electroplating solution catch
cup 246 showing three rinse spouts 260 disposed on a bottom surface
of the electroplating solution catch cup 246.
[0036] FIG. 16 is a top view of a rinse catch cup 264.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] The invention generally provides an electro-chemical
deposition cell wherein a substrate is positioned with a deposition
surface "face up." An electroplating solution is pumped through a
top portion of the cell over the exposed substrate deposition
surface and collected in a peripheral catch cup drain about the
perimeter of the substrate. Additionally, the cell includes means
for in situ cleaning and/or rinsing of the electro-chemically
deposited substrate.
[0038] FIG. 2 is a partial cut-away perspective view of an
electro-chemical deposition cell showing the interior components of
the electro-chemical deposition cell. Generally, the
electro-chemical deposition cell 200 comprises a substrate support
member 204, a cathode clamp ring 210, an anode plate 230 above the
cathode clamp ring 210 and an electroplating solution inlet 240
supplying an electroplating solution into the electro-chemical
deposition cell 200 above the substrate or in the flow direction of
the substrate surface to be plated.
[0039] The electro-chemical deposition cell 200 includes a cell
enclosure 100 comprising an enclosure lid 102, an enclosure side
wall 104 and an enclosure bottom 106. Preferably, the enclosure 100
has a cylindrical interior and is made of an electrically
insulative material. The enclosure side wall 104 includes a slit
opening 280 for transfer of substrates into and out of the
electro-chemical deposition cell 200, and a slit valve 282 disposed
on an outer surface of the enclosure side wall 104 opens only
during the substrate transfer operation and covers the slit opening
280 during processing to provide a sealed processing environment. A
drip awning 284 is preferably disposed above the slit opening 280,
extending inwardly from an inner surface of the enclosure side wall
104, to guard the opening 280 from direct receipt of the
electroplating solution and thus prevent a processing solution from
leaking out of the cell through the slit opening 280.
[0040] Referring to FIG. 3, where the electro-chemical deposition
cell 200 is shown with the substrate support member 204 in a
load/transfer position, as well as FIG. 4, where the
electro-chemical deposition cell 200 is shown in a
plating/processing position, the anode plate 230 is disposed within
a cavity ring 236 at a top portion of the electro-chemical
deposition cell 200. The anode plate 230 is electrically connected
to a power supply 90. The substrate support member 204 is disposed
at a bottom portion of the electro-chemical deposition cell 200.
The cathode clamp ring 210, preferably supported by an annular
electroplating solution catch cup 246, is disposed in a middle
portion of the electro-chemical deposition cell 200 between the
substrate support member 204 and the anode plate 230. The cathode
clamp ring 210 is positioned in the electro-chemical deposition
cell 200 such that the movement of the substrate support member 204
from the load/transfer position (FIG. 3) to the processing position
(FIG. 4) lifts the cathode clamp ring 210 slightly off the annular
electroplating solution catch cup 246. Once in the processing
position, an electroplating solution pump 92, which is connected to
the electroplating solution inlet 240, pumps the electroplating
solution from an electroplating solution reservoir 94 into the
electro-chemical deposition cell 200. Preferably, an electroplating
solution outlet 258 is connected to an electroplating solution
drain 244 on the electroplating solution catch cup 246 to return
the electroplating solution back to the electroplating solution
reservoir 94 to be re-circulated through the electro-chemical
deposition cell 200.
[0041] FIG. 3 is a cross sectional schematic view of an
electro-chemical deposition cell 200 showing a robot blade 88
transferring a substrate 202 into the electro-chemical deposition
cell 200, and FIG. 5 is a cross sectional schematic view of a
substrate support member 204 in a transferring position according
to the invention. By comparing FIGS. 2A and 3A, the sequence for
loading and unloading a substrate may be seen. Referring initially
to FIG. 3, a robot blade 88 transfers a substrate 202 into the
electro-chemical deposition cell 200 through the slit opening 280
and positions the substrate 202 above the substrate support member
204. At the substrate transferring position, the substrate support
member 204 is retracted fully to a bottom portion of the
electro-chemical deposition cell 200. Then, as shown in FIG. 5, a
plurality of lift pins 322 extend through vertical bores 324 in the
substrate support member 204 and lift the substrate 202 above the
robot blade 88. The robot blade 88 then retracts out of the
chamber, and the slit valve 282 closes the slit opening 280.
[0042] Referring to FIG. 5, the substrate support member 204
comprises a vacuum chuck 290 made of an insulating material and a
conductive base plate 292 providing a cathode connection to the
cathode clamp ring 210. The vacuum chuck 290 secures a substrate
202 onto a substrate supporting surface 206 on the substrate
support member 204 during processing. Preferably, one or more
vacuum ports 294 are disposed in the substrate support member 204
and are connected to one or more vacuum channels 296 disposed on
the substrate supporting surface 206 to secure the substrate 202
through vacuum suction. The vacuum channels 296 are generally
disposed evenly across the surface of the substrate member in a
web-like fashion (as shown in FIG. 2).
[0043] An outer seal 298, comprising an O-ring, or alternatively, a
double O-ring, disposed in a recess 300 surrounding the substrate
supporting surface 206 is provided to create a vacuum seal between
a backside 215 of the substrate 202 and the substrate supporting
surface 206 when the vacuum chuck 290 is activated. The outer seal
298 also provides a seal against substrate backside contamination
by the electroplating solution and other processing solutions.
Eliminating the substrate backside contamination eliminates the
need for a post deposition backside cleaning process, thus reducing
system cost and complexity.
[0044] To provide a vacuum passage to the substrate supporting
surface 206, a vacuum conduit 302 within the vacuum chuck 290
connects the vacuum ports 294 and vacuum channels 296 to a central
vacuum conduit 304 within a rotating shaft 306. The rotating shaft
306 extends through a shaft sleeve 308 and is connected to a rotary
actuator 310 disposed on a platform 342. The shaft sleeve 308 is
also disposed on the platform 342 to maintain a fixed vertical
relationship with the rotating shaft 306. A set of lip seals 314
disposed between the rotating shaft 306 and the shaft sleeve 308
allows free rotational movement of the rotating shaft 306 within
the shaft sleeve 308 while providing a sealed region 316 between an
outer surface of the rotating shaft 306 and an inner surface of the
shaft sleeve 308. The central vacuum conduit 304 includes an
opening 312 fluidly connecting the central vacuum conduit 304 and
the sealed region 316. A vacuum outlet 318 extends through the
shaft sleeve 308 and fluidly connects to the sealed region 316. A
vacuum pump 360 is connected to the vacuum outlet 318 to provide a
vacuum suction through the vacuum outlet 318, the sealed region
316, the opening 312, the central vacuum conduit 304, the vacuum
conduit 302, the vacuum ports 294 and the vacuum channels 296 to
hold the substrate 202 on the substrate support surface 206.
[0045] To provide a positive pressure between the substrate and the
substrate support member 204, a gas pump 370 connected to a gas
supply 372 is selectively connected through a control valve 374 to
the vacuum outlet 318 to supply a blow off gas to the vacuum ports
294. The blow off gas prevents leftover rinsing agent from
contaminating the backside of the processed substrate when the
substrate is lifted above the substrate support member 204 and
transferred out of the electro-chemical deposition cell 200. The
control valve 374 shuts the connection to the vacuum pump 360 when
the gas pump 370 is activated to pump the blow-off gas to the
vacuum ports 294, and the control valve 274 shuts the connection to
the gas supply 372 and the gas pump 370 when the vacuum pump 360 is
activated to hold the substrate 202 on the support member 204. The
vacuum ports 294 direct the blow off gas toward the backside edge
of the substrate 202 to prevent any leftover rinsing agent from
reaching the backside 215 of the substrate 202.
[0046] FIG. 6 is a cross sectional view of an alternative
embodiment of the substrate support member 204 showing two separate
fluid conduits and dual level lip seals. Although the following
describes a fluid delivery system for two separate fluids, the
fluid delivery system may be adapted to accommodate a number of
separate fluids by increasing the number of fluid conduits and lips
seals. The embodiment as shown in FIG. 6 provides a substrate
support member 204 capable of rotating while delivering two
separate fluids through separate fluid conduits to the substrate
support surface 206. Preferably, two separate sets of fluid
channels 396A, 396B and fluid ports 394A, 394B are disposed on the
substrate supporting surface 214, and two sets of fluid conduits
402A, 402B within the vacuum chuck are connected to two sets of
central fluid conduits 404A, 404B extending through the rotating
shaft 306. The first central fluid conduit 404A includes a first
opening 412A fluidly connecting the first central fluid conduit
404A and a first sealed region 416A sealed by a first set of lip
seals 414A. A first fluid inlet 418A extends through the shaft
sleeve 308 and fluidly connects to the first seal region 416A. A
first fluid supply 420A is connected to the first fluid inlet 418A
through a first pump 422A. Likewise, the second central fluid
conduit 404B includes a second opening 412B fluidly connecting the
second central fluid conduit 404B and a second sealed region 416B
sealed by a second set of lip seals 414B. A second fluid inlet 418B
extends through the shaft sleeve 308 and fluidly connects to the
second seal region 416B. A second fluid supply 420B is connected to
the second fluid inlet 418B through a second pump 422B. The sets of
lip seals 414A. 414B disposed between the rotating shaft 306 and
the shaft sleeve 308 allows free rotational movement of the
rotating shaft 306 within the shaft sleeve 308 while providing the
sealed regions 416A, 416B between an outer surface of the rotating
shaft 306 and an inner surface of the shaft sleeve 308. Thus, two
separate fluids can be simultaneously delivered to the substrate
supporting surface 214 while the substrate support member 204 is
rotated. Alternatively, one of the pumps 422A and 422B is
substituted with a vacuum pump to provide separate routes of vacuum
suction and gas delivery to the substrate supporting surface 214.
As another alternative, both of the gas pumps 422A and 422B may be
substituted with two vacuum pumps to provide differential vacuum
regions at the substrate supporting surface 214. Furthermore, more
than two vacuum or fluid pumps may be used depending on the
processing requirement. Although each sealed region described above
preferably uses one set of lip seals (i.e., two lip seals), a
subsequent sealed region (i.e., other than the first sealed region)
requires only one additional lip seal. For example, three lip seals
can create two sealed regions, one between the first lip seal and
the second lip seal and another between the second lip seal and the
third lip seal.
[0047] Referring back to FIG. 5, the rotating shaft 306 extends
through a lift pin platform 320 having a plurality of lift pins 322
disposed thereon. The lift pins 322, preferably a set of four,
extend through bores 324 through the substrate support member 204
to lift a substrate 202 above the substrate support surface 206. A
lift platform actuator 326 moves the lift pin platform 320
vertically to lift and lower a substrate 202 for transfer into and
out of the electro-chemical deposition cell 200. Preferably, the
lift platform actuator 326 is disposed on an outer surface of the
shaft sleeve 308 and includes a push rod 327 to actuate movement of
the lift pin platform 320. To elevate the lift pin platform 320,
the lift platform actuator 326 extends the push rod 327 to contact
a bottom surface of the lift pin platform 320 and push the lift pin
platform 320 upwards. To lower the lift pin platform 320, the lift
platform actuator 326 retracts the push rod 327 to disengage the
lift pin platform 320. When the push rod 327 of the lift platform
actuator 326 is fully retracted, the push rod 327 does not contact
the lift pin platform 320, and the lift pin platform 320 rests on a
platform ridge 329 extending from an outer surface of the rotating
shaft 306 above the shaft sleeve 308.
[0048] One or more vertical tabs 328 extend from an upper portion
of the outer surface of the rotating shaft 306 into one or more
matching vertical grooves 330 in the lift pin platform 320 so that
the lift pin platform 320 rotates in unison with the rotating shaft
306. The tabs 328 also guide the lift pin platform 320 vertically
when the lift pin platform is being moved by the lift platform
actuator 326.
[0049] A flexible bellow 332, preferably made of polyethylene, is
disposed around each lift pin 322 to provide a splash seal against
electroplating solutions, rinsing solutions and other process
chemicals. The flexible bellow 332 is attached from a top surface
of the lift pin platform 320 to a bottom surface of the conductive
base plate 292 of the substrate support member 204. The flexible
bellow 332 compresses when the lift pin platform 320 is elevated by
the lift platform actuator 326 and stretches when the lift pin
platform 320 is resting on the platform ridge 329. Each flexible
bellow 332 also maintains a seal when subjected to a slight side
load, such as when the substrate support member rotationally
accelerates or decelerates.
[0050] To prevent electroplating solutions, rinsing solutions and
other process chemicals from contacting components disposed in the
central portion of the electro-chemical deposition cell 200, such
as the lift platform actuator 326 and the shaft sleeve 308, a
splash guard 333 is attached to an outer portion of a lower surface
of the lift pin platform 320. The splash guard 333 includes a
cylindrical downward extension 334 that is disposed radially
outward of an upwardly extending inner container wall 336. The
inner container wall 336 is a cylindrical upward extension from the
enclosure bottom 106 of the electro-chemical deposition cell 200
that holds the process solutions to be pumped out of the system
through the outlet 259. The splash guard 334 and the inner
container wall 336 create a sufficient overlap so that when the
lift pin platform 320 is raised to it highest position during
processing, there is still an overlap between the tip of the splash
guard 334 and the tip of the inner container wall 336 (as shown in
FIG. 4).
[0051] To provide rotational movement to the substrate support
member 204, a rotary actuator 310 is disposed on a platform 342 and
connected to the rotating shaft 306. The rotary actuator 310
rotates the rotating shaft 306 freely within the shaft sleeve 308.
To move the substrate support member 204 vertically, an actuator
346 extends and retracts a shaft 344 connected to the platform 342.
The actuator 346 is disposed outside of the enclosure 100 on the
enclosure bottom 106, and the shaft 344 extends through the
enclosure bottom 106 and is attached to a bottom surface of the
platform 342. To maintain a fixed vertical relation with the
rotating shaft 306 when the substrate support member 204 is
elevated and lowered in the electro-chemical deposition cell 200,
the shaft sleeve 308 is also disposed on the platform 342.
Preferably, the actuator 346 also provides a vibrational agitation
to the substrate support member 204 to enhance deposition onto the
substrate deposition surface 214. Alternatively, a vibrator (not
shown) can be attached to the substrate support member 204 to
provide the vibrational agitation.
[0052] Referring to FIG. 3 and FIG. 4, the structure, operation and
positioning of a cathode clamp ring 210 and an electroplating
solution catch cup 246 will be discussed. The catch cup 246 is an
annular structure extending inwardly from the enclosure side wall
104 of the electro-chemical deposition cell 200 to a bottom surface
220 of the cathode clamp ring 210. The cathode clamp ring 210
preferably includes an outer portion having a downwardly sloping
surface 256 that overlaps an inner terminus 250 of the catch cup
246 to assist the electroplating solution flow into the catch cup
246. The inner terminus 250 includes a ridge 252 corresponding to a
recess 254 on the bottom surface 220 of the cathode clamp ring 210.
The ridge 252 supports the cathode clamp ring 210 when the
substrate support member 204 is not engaged in a deposition
position. When the substrate support member is engaged in the
deposition position as shown in FIG. 4, the cathode clamp ring 210
is lifted from the ridge 252 and is supported on the substrate
deposition surface 214.
[0053] The electrical power is delivered by the cathode clamp ring
210 to the substrate deposition surface 214 through a contact
portion 208 of the cathode clamp ring 210. To provide electrical
power to the cathode clamp ring 210, one or more cathode contacts
216 are fixedly secured to a bottom surface 218 of the conductive
base plate 292 of the substrate support member 204 and extends
radially outwardly to electrically contact a bottom surface 220 of
the cathode clamp ring 210. The electrical power is conducted
through the rotating shaft 306 to the conductive base plate 292,
then through one or more cathode contacts 216 secured onto the
conductive base plate 292, and then to a bottom surface 220 of the
cathode clamp ring 210. Preferably, the cathode contact 216
comprises a spring loaded metal strip that maintains constant
electrical contact with the bottom surface 220 of the cathode clamp
ring 210 during processing when the substrate support member 204 is
rotated and/or vibrated. Alternatively, the cathode clamp ring 210
is fixedly connected to the power supply through connection wires
(not shown).
[0054] To provide electrical power to the cathode clamp ring 210
while rotating the substrate support member 204 and the rotating
shaft 306, a rotating cathode connection 340 is disposed at a top
portion of the shaft sleeve 308 and connected to the power source
90. The rotating shaft 306 preferably comprises an electrically
conductive material, and the rotating cathode connection 340
movably contacts the outer surface of the rotating shaft 306 to
maintain electrical conduction to the rotating shaft 306 while the
rotating shaft 306 is rotating. The rotating cathode connection 340
preferably comprises a plurality of conductive ball bearings 341
disposed between a pair of ring seals 343. Preferably, the rotating
cathode connection 340 is filled with mercury to enhance the
electrical conductivity of the rotating cathode connection 340
while the rotating shaft 306 is rotated.
[0055] Preferably, the cathode clamp ring 210 comprises an annular
conductive member having a central opening defining the deposition
area on a substrate deposition surface that is exposed to the
electroplating solution during processing. The cathode clamp ring
210 is electrically connected to the power source 90 through the
cathode contacts 216 and the substrate support member 204 and
includes a contact portion 208 to electrically contact the
substrate deposition surface 214 and to provide an electrical power
(voltage and current) to the substrate deposition surface 214 to
enable the electro-chemical deposition process. The contact portion
208 preferably extends a minimal radial distance inward above a
perimeter edge 212 of the substrate 202, but a distance sufficient
to electrically contact a metal seed layer on the substrate
deposition surface 214. Preferably, the contact portion 208
includes an annular surface providing a continuous contact around a
peripheral portion of the substrate deposition surface 214. By
providing a continuous electrical interface between the cathode and
the substrate deposition surface, the electrical power is uniformly
distributed on the substrate deposition surface 214. The increase
in the electrical interface, as compared to an individual contact
finger arrangement, also minimizes the fringing effect that occurs
with individual cathode contact pins that cause non-uniform
deposition. Alternatively, the contact portion 208 comprises a
plurality of contact pads 217 (as shown in FIG. 7) positioned to
contact substantially around the peripheral portion of the
substrate deposition surface 214.
[0056] While the cathode clamp ring 210 is engaged with the
substrate 202, cathode clamp ring 210 rotates with the substrate
support member 204 because of the frictional force between the
contact portion 208 and the substrate deposition surface 214.
Preferably, the cathode clamp ring 210 includes a plurality of
locking grooves (not shown) disposed on the bottom surface 220 to
receive the cathode contacts 216. With the cathode contacts 216
engaged in the locking grooves, the cathode clamp ring 210 rotates
synchronously with the substrate support member 204 without
depending on the frictional force between the contact portion 208
and the substrate deposition surface 214.
[0057] FIG. 8 is a partial cross sectional schematic view of
another embodiment of a cathode clamp ring. In this embodiment, the
cathode clamp ring 210 includes a contact portion 208 comprising a
metal impregnated elastomer ring 350 electrically contacting a
peripheral portion of the substrate deposition surface 214. The
metal impregnated elastomer ring 350 is disposed on a ridge 351 on
a stepped surface 209 of the cathode clamp ring 210. The metal
impregnated elastomer ring 350 is secured to the stepped surface
209 of the cathode clamp ring 210 by an adhesive that is unaffected
by the electroplating solution and process. Alternatively, the
metal impregnated elastomer ring 350 is secured to the stepped
surface 209 of the cathode clamp ring 210 by a fastener (not shown)
such as a screw or a bolt. As another alternative, the cathode
clamp ring 210 includes an annular dove-tail groove (not shown)
disposed on the stepped surface 209 that squeezes and holds the
metal impregnated elastomer ring 350.
[0058] The metal impregnated elastomer ring 350 provides electrical
conduction through metal particles or short wires disposed in a
hydrophobic elastomer matrix. FIG. 9 is a cut-away perspective of a
section of an embodiment of a metal impregnated elastomer ring 350.
The metal impregnated elastomer ring 350 generally comprises an
outer elastomer ring 352, an inner elastomer ring 354 and a metal
ring 356 sandwiched between the inner elastomer ring 352 and the
outer elastomer ring 354. Preferably the metal ring 356 comprises a
plurality of individual metal wires 358 extending at a slanted
angle a (other than perpendicular to a top and/or a bottom surface
of the elastomer ring 350) from a top surface of the elastomer ring
350 to a bottom surface of the elastomer ring 350. The metal wires
358 conduct electrical power from the cathode clamp ring 210 to the
substrate deposition surface 214. A top end 357 of the metal wires
358 contacts the cathode clamp ring 210, and a bottom end 359 of
the metal wires 358 contacts the substrate deposition surface 214.
The slanted angle a of the metal wires 358 enhances the ability of
the metal impregnated elastomer ring 350 to compress and form a
seal on the substrate deposition surface 214 while providing
electrical contact to the substrate deposition surface 214, i.e.,
by the individual metal wires sliding relative to each other and
increasing the angle a as needed. One exemplary metal impregnated
elastomer ring is available from Shin-Etsu Handotai America, Inc.,
Vancouver, Wash. The metal impregnated elastomer ring 350 provides
a compliant contacting interface with the substrate deposition
surface 214 that reduces the risk of scratching the substrate
deposition surface 214 by the contact portion 208 of the cathode
clamp ring 210. The metal impregnated elastomer ring 350 also seals
the contact interface from the process solutions so that the metal
conductors in the elastomer matrix are not exposed to the
processing solutions which can change the properties of the metal
conductors. Although one embodiment of the metal impregnated matrix
is discussed above, the invention contemplates other embodiments of
metal impregnated elastomers having different arrangements of
electrically conductive particles within the elastomer matrix for
use as the contact portion 208 of the cathode clamp ring 210.
[0059] FIG. 10 is a cross sectional partial view of a cathode clamp
ring showing another embodiment of a contact portion of the clamp
ring. In this embodiment, the contact portion 208 of the cathode
clamp ring 210 comprises an annular downward extension of the
conductive metal from a bottom surface 209 of the cathode clamp
ring 210. The annular down ward extension is preferably a
wedge-shaped annular ring. An inner concentric O-ring 211 and an
outer concentric O-ring 213 are attached to the bottom surface 209
of the cathode clamp ring 210 surrounding the contact portion 208.
The O-rings 211 and 213 provide a sealed environment for the
contact portion 208 during the electro-chemical deposition process
while the contact portion 208 conducts electrical power to the
substrate deposition surface 214.
[0060] Referring back to FIG. 8, an alternative embodiment of a
support for the cathode clamp ring 210 utilizes a kinematic
coupling between the cathode clamp ring 210 and the inner terminus
250 of the catch cup 246. Utilizing kinematic coupling allows
positive location of concentric parts such as the cathode clamp
ring 210 in relation with the electroplating solution catch cup
246. The kinematic coupling generally comprises a plurality of ball
bearings 361 (only one shown) disposed partially in a plurality of
seats 363 on a top surface of the inner terminus 250 and a
corresponding groove 362 on a bottom surface of the cathode clamp
ring 210 to receive a top portion of the ball bearing 361.
Preferably, the kinematic coupling uses three ball bearings 361 to
center the cathode clamp ring 210. One ball bearing locates the
radial position while the other two ball bearings locate the
angular position of the clamp ring 210.
[0061] Referring to FIG. 11, where a top view of an electroplating
solution catch cup 246 is shown, preferably two electroplating
solution drains 244 are disposed diametrically in opposing corners
of the electro-chemical deposition cell 200. Referring back to FIG.
3 and FIG. 4, the electroplating solution catch cup 246 is disposed
in a middle portion of the electro-chemical deposition cell 200 to
direct the electroplating solution to one or more electroplating
solution drains 244. During processing, the electroplating solution
is pumped through the electroplating solution inlet 240 into the
cavity 242, passes through the anode plate 230 onto the substrate
deposition surface 214 (see FIG. 4) and then flows over a cathode
clamp ring 210 into an electroplating solution drain 244 of a catch
cup 246. The catch cup 246 includes a downwardly sloping top
surface 248 from an inner terminus 250 to the electroplating
solution drain 244 to direct the electroplating solution
overflowing the cathode clamp ring 210 to the electroplating
solution drain 244. The size (inner diameter) of the electroplating
solution drain 244 and the slope and length of the top surface 248
is adapted to accommodate a particular flow rate so that the
electroplating solution does not overflow the catch cup 246 and
spill over the ridge 252. The electroplating solution drain 244 is
connected to an electroplating solution outlet 258 that transports
the processed electroplating solution to the electroplating
solution reservoir 94. The electroplating solution is then pumped
to the electroplating solution inlet 240 and re-circulates through
the electro-chemical deposition cell 200.
[0062] Referring back to FIG. 3 and FIG. 4, a cavity ring 236
comprising a generally cylindrical structure is disposed at a top
potion of the electro-chemical deposition cell 200 to hold an anode
plate 230 and the electroplating solution to be distributed through
the anode plate 230. The anode plate 230 is disposed at a bottom
portion of the cavity ring 236 on a ridge 232 extending inwardly
from an inner surface 234 of the cavity ring 236. The inner surface
234 of the cavity ring 236 and the top surface 231 of the anode
plate 230 define a cavity 242 for holding the electroplating
solution to be distributed through the anode plate 230. An
electroplating solution inlet 240 disposed on the enclosure lid 102
supplies the electroplating solution into the cavity 242. The
electroplating solution inlet 240 is connected to an electroplating
solution pump 92 that pumps the electroplating solution from an
electroplating solution reservoir 94.
[0063] Preferably, the anode plate 230 has substantially the same
shape as the substrate deposition surface 214 and includes a
plurality of perforations to distribute the electroplating solution
uniformly across the substrate deposition surface 214. The anode
plate 230 is electrically connected to a power source 90 and
preferably comprises a consumable metal that can dissolve in the
electroplating solution to provide the metal particles to be
deposited onto the substrate deposition surface 214. As the
electroplating solution passes through an energized anode plate
230, metal ions dissociate from the surface of the consumable metal
anode plate 230 into the electroplating solution.
[0064] Alternatively, the anode plate 230 comprises an electrode
and consumable metal particles encased in a fluid permeable
membrane such as a porous ceramic plate. An alternative to the
consumable anode plate is a non-consumable anode plate that is
perforated or porous for passage of the electroplating solution
therethrough. However, when a non-consumable anode plate is used,
the electroplating solution requires a metal particle supply to
continually replenish the metal particles to be deposited in the
process.
[0065] To enhance the deposition process, an agitator 237 is
preferably attached to the cavity ring 236 to agitate the
electroplating solution. The agitator 237 generally comprises a
megasonic or an ultrasonic finger that transfers a vibration to the
electroplating solution by vibrating the cavity ring 236.
[0066] After the electroplating process is finished, no more
electroplating solution is pumped into the cell 200, and the
electroplating solution is drained from the cell 200 through the
electroplating solution drains 244. However, some electroplating
solution may collect on the anode plate 230 and the cavity ring 236
and then drip onto the processed substrate deposition surface 214.
To control dripping of residual electroplating solution from the
anode/cavity ring assembly to the substrate deposition surface
after the deposition phase, the anode/cavity ring assembly is
preferably moved away from the region above the substrate.
[0067] FIG. 12 shows one embodiment of the anode/cavity ring
assembly for drip control where a substrate support member 204 is
shown positioned in a rinsing position according to the invention.
Preferably, the assembly of the cavity ring 236 and the anode plate
230 comprises two symmetrical halves split by a central vertical
plane. An actuator 237 is connected to each half to pull apart the
anode/cavity ring assembly after the deposition phase of the
process. Each half of the anode/cavity ring assembly is moved to
the region above the electroplating solution catch cup 246 so that
the residual electroplating solution drips into the electroplating
solution catch cup.
[0068] FIG. 13 is a top view of a shutter plate 238 positioned
above cathode clamp ring 210, showing an alternative solution for
controlling the dripping of residual electroplating solutions from
the anode/cavity ring assembly. A shutter plate 238 moves into the
region between the anode/cavity ring assembly and the cathode clamp
ring 210 to block the dripping residual electroplating solution
from contaminating the processed substrate deposition surface.
Preferably, the shutter plate 238 is attached to a rotary shutter
actuator 239 and retracted into a shutter plate chamber 237 during
the deposition process. Once the deposition phase is completed, the
rotary shutter actuator 239 rotates the shutter plate 238 below the
anode/cavity ring assembly and blocks the dripping residual
electroplating solution.
[0069] FIG. 14 is a side view of an electro-chemical deposition
cell having a sub-chamber for the anode/cavity ring assembly. The
anode/cavity ring assembly is attached to a rotary assembly
actuator 241 that moves the anode/cavity ring assembly into a
sub-chamber 243 after the deposition phase of the process. By
moving the anode plate 230 and the cavity ring 236 into the
sub-chamber 243, the residual electroplating solution drips in the
sub-chamber 243 and is prevented from contaminating the processed
substrate deposition surface.
[0070] A layer of electroplating solution is typically left on the
processed substrate deposition surface after the deposition phase
of the process. To remove residual electroplating solution from the
processed substrate deposition surface, a rinse agent is sprayed
over the surface, and then the substrate is spun dry. Referring
back to FIG. 3, a rinsing agent reservoir 96 supplies the rinse
agent and is connected to a rinse agent manifold 261 through a
rinse agent pump 97. One or more rinse spray spouts 260 are
connected to the rinse agent manifold 261 to spray a rinse agent,
such as deionized water or nitrogen gas, over the processed
substrate deposition surface.
[0071] Referring now to FIG. 12, a substrate support member 204 is
shown positioned in a rinsing position according to the invention.
Preferably, one or more rinse spray spouts 260 are disposed on a
bottom surface 262 of the inner terminus 250 of the electroplating
solution catch cup 246. The rinse spray spouts 260 spray the rinse
agent over the processed substrate deposition surface 214 after
completion of the electro-chemical deposition process when the
substrate support member 214 is lowered to a rinsing position. At
the rinsing position, the substrate support member 204 is
positioned below a horizontal plane defined by the rinse spray
spouts 260 but above a horizontal plane defined by the tip of a
rinse catch cup 264.
[0072] FIG. 15 is a bottom view of an electroplating solution catch
cup 246 showing three rinse spouts 260 disposed on a bottom surface
of the electroplating solution catch cup 246. Preferably, the rinse
spouts 260 spray a mist of rinse agents over the processed
substrate deposition surface 214. The rinse agent collect on the
processed substrate deposition surface 214 to create a sheeting
action of the rinse agent that removes the residual electroplating
solution from the processed substrate deposition surface 214. The
substrate support member 204 is then rotated to spin dry the
substrate and remove the rinse agent from the processed substrate
deposition surface 214.
[0073] FIG. 16 is a top view of a rinse catch cup 264. Referring to
both FIG. 12 and FIG. 16, a rinse catch cup 264 is disposed below
the electroplating solution catch cup 246 and extends inwardly from
the enclosure side wall 104 of the electro-chemical deposition cell
200 to direct overflowing rinse agents and any residual
electroplating solution to a rinse drain 270. The inner terminus
266 of the rinse catch cup 264 defines an opening which outlines
the circumference of the substrate support member 204 and allows
the passage of the substrate support member 204 therethrough. The
rinse catch cup 264 includes a downwardly sloping top surface 268
from the inner terminus 266 to a rinse drain 270. The rinse spray
spout 260 sprays the rinse agent over the processed substrate
deposition surface 214 to clean the deposited surface and to remove
any excess electroplating solution remaining on the substrate
deposition surface 214. As the substrate is spun dry, the rinse
agent flows over the deposited substrate surface into the rinse
catch cup 264 to the rinse drain 270 that drains the rinse agent to
a bottom portion of the cell 200. The lower portion of the
electro-chemical deposition cell 200 serves as a catch bowl, and an
outlet 259 on the enclosure bottom 106 returns the used rinse
solution to a purifier 98 and then back to the rinse solution
reservoir 96 to be re-used for subsequent rinses (shown in FIG. 3).
The rinse agent is then pumped out of the electro-chemical
deposition cell 200 through an outlet 259 into a rinse agent
reservoir 96.
[0074] In operation, a substrate 202 is transferred into the
electro-chemical deposition cell 200 by a robot blade 88 through
the slit opening 280 over a substrate support member 204 that is
retracted fully. FIG. 3 is a cross sectional schematic view of an
electro-chemical deposition cell 200 showing a robot blade
transferring a substrate 202 into the electro-chemical deposition
cell 200. A slit valve 282 is opened during the substrate transfer,
and a robot blade 88 having a substrate 202 thereon enters the
electro-chemical deposition cell 200 through the slit opening 280.
The substrate 202 is positioned above the substrate support member
204, and the lift pin platform is elevated. The substrate 202 is
lift above the robot blade 88 by the lift pins 272 on the lift pin
platform 320 that is elevated by the lift platform actuator 326
extending the push rod 327. The robot blade 88 then retracts out of
the electro-chemical deposition cell 200 and the slit valve 282
closes to seal the processing environment. FIG. 3 is a cross
sectional schematic view of the electro-chemical deposition cell
200 showing a substrate positioned over a substrate support member
204 and supported by lift pins 272. The lift platform actuator 326
retracts the push rod 327 to lower the lift pin platform 320 and
position the substrate 202 onto the substrate supporting surface
206 and the outer seal O-ring 298. The vacuum chuck 290 engages the
vacuum suction to hold the substrate 202 on the substrate
supporting surface 206, and the outer seal (O-ring) 298 seals the
backside of the substrate 202 from the processing chemicals.
[0075] The actuator 346 then elevates the support member 204 to the
processing position. FIG. 4 is a cross sectional schematic view of
an electro-chemical deposition cell 200 having a substrate 202
disposed on a substrate support member 204 in a processing position
according to the invention. At the processing position, the
substrate 202 engages the cathode clamp ring 210, and an electrical
power is delivered through the contact portion 208 of the cathode
clamp ring 210 to the substrate deposition surface 214. An
electroplating solution is pumped through the solution inlet 240 at
the enclosure top 102 into the cavity ring 236 above the anode
plate 230. The electroplating solution passes through the anode
plate 230 onto the substrate deposition surface 214 to deposit a
metal layer thereon.
[0076] During the deposition process, the rotary actuator 310
rotates the substrate support member 204 about a central axis
through the rotating shaft 306 at between about 10 revolutions per
minute (RPM) to about 50 RPM, and the actuator 346 provides a
vibrational agitation to the substrate support member 204. The
rotation and the agitation of the substrate support member 204
provide a uniform exposure of the electroplating solution to the
substrate deposition surface 214 and promote uniform deposition
thereon. Deposition uniformity is also improved by the continuous
cathode contact provided by the cathode clamp ring 210 that
distributes a uniform current density across the substrate
deposition surface 214.
[0077] To enhance filling of high aspect ratio features on the
substrate deposition surface, a plate/de-plate scheme is applied
during the deposition phase of the process. The plate/deplate
scheme generally comprises periodic reversal of the electrical
current flowing through the electroplating solution between the
cathode and the anode. During the plating period, the cathode and
the anode are biased normally to cause electro-chemical deposition
onto the cathode. During the deplating period, the cathode and the
anode are reverse biased and the electrical current is reversed to
cause de-plating of the deposited surface. However, because a
higher electrical current is applied for a shorter duration during
the de-plating period, as compared to the plating period, the
de-plating period removes the crowning or bridging effect at the
mouth of the aperture of high aspect ratio features and enhances
filling of the feature for the subsequent plating period.
[0078] After the electroplating solution flows over the substrate
deposition surface 214, the electroplating solution flows over the
cathode clamp ring 210 into the electrolyte catch cup 246. The
electroplating solution then flows through the electrolyte drain
244 and is pumped out of the electro-chemical deposition cell 200
through outlet 258. Preferably, the electroplating solution is
re-circulated through the electro-chemical deposition cell 200
until the end of the deposition process. Then, the electroplating
solution is evacuated from the electro-chemical deposition cell 200
into the electrolyte reservoir 94 until the next deposition
process. Preferably, as the electroplating solution is evacuated,
the rotational actuator 310 rotates the substrate support member
204 at a speed sufficient to spin dry the substrate deposition
surface 214 by centrifugal force. The substrate support member 204
preferably spins at least about 100 RPM to spin dry the substrate
202.
[0079] After the deposition process, the actuator 346 lowers the
substrate support member 204 to a rinsing position. The substrate
202 is preferably positioned below a horizontal plane defined by
the rinse spray spouts 260 but above a horizontal plane defined by
the tip of the rinse catch cup 264. The rinse spray spouts 260
spray the rinse agent over the processed substrate deposition
surface 214 to clean the deposited surface and to remove any excess
electroplating solution remaining on the substrate deposition
surface 214. To end the rinse process, the substrate support member
204 rotates at a speed at least about 100 RPM to spin dry the
substrate deposition surface 214 through centrifugal force. The
rinse agent is drained through the rinse drain 270 to the bottom of
the cell 200 and pumped out of the cell 200 through outlet 259 into
a rinse agent reservoir 96.
[0080] After the rinse process, the actuator 346 retracts fully and
lowers the substrate support member 204 to the transfer position as
shown in FIG. 3. The vacuum chuck 290 disengages the vacuum suction
and releases the substrate 202, and the lift platform actuator 326
extends the push rod 327 to elevate the lift pin platform 320 and
the lift pins 272 to lift the processed substrate 202 above the
substrate support surface 206. As the lift pins 272 lift the
substrate 202 above the substrate support surface 206, a blow-off
gas is pumped through the vacuum chuck 290 out of the vacuum port
294 to provide a gas flow directed at the backside edge of the
substrate 202. The blow-off gas prevents any remaining rinse agent
from contaminating the backside 215 of the substrate 202. The slit
valve 282 opens, and the robot blade 88 extends into the
electro-chemical deposition cell 200 through the slit 280. The
robot blade 88 is positioned under the elevated substrate 202, and
the lift pins 272 are lowered to position the substrate 202 onto
the robot blade 88. The robot blade 88 then retracts out of the
electro-chemical deposition cell 200 with the processed substrate,
and the process repeats for the next unprocessed substrate.
[0081] 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. The scope of the invention is determined by the claims
which follow.
* * * * *