U.S. patent application number 10/410105 was filed with the patent office on 2004-10-14 for application of antifoaming agent to reduce defects in a semiconductor electrochemical plating process.
This patent application is currently assigned to Applied Materials Inc.. Invention is credited to Mostovoy, Roman, Wen, Mei, Yahalom, Joseph.
Application Number | 20040200725 10/410105 |
Document ID | / |
Family ID | 33130733 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040200725 |
Kind Code |
A1 |
Yahalom, Joseph ; et
al. |
October 14, 2004 |
Application of antifoaming agent to reduce defects in a
semiconductor electrochemical plating process
Abstract
Embodiments of the invention provide a method and formulations
for preventing foam formation inside a plating apparatus prior to
or during plating a material on a substrate. In one embodiment, a
method for preventing foam formation inside a plating apparatus
designed for plating a material on a substrate includes providing
an electrolyte solution containing at least one antifoaming agent,
at least one metal ion source, and a supporting electrolyte. The
method further includes placing the substrate onto a substrate
holder of the plating apparatus, immersing the substrate in the
electrolyte solution, and depositing the material onto the
substrate.
Inventors: |
Yahalom, Joseph;
(Emeryville, CA) ; Wen, Mei; (King of Prussia,
PA) ; Mostovoy, Roman; (San Francisco, CA) |
Correspondence
Address: |
PATENT COUNSEL
APPLIED MATERIALS, INC.
Legal Affairs Department
P.O. BOX 450A
Santa Clara
CA
95052
US
|
Assignee: |
Applied Materials Inc.
|
Family ID: |
33130733 |
Appl. No.: |
10/410105 |
Filed: |
April 9, 2003 |
Current U.S.
Class: |
205/98 ;
257/E21.175 |
Current CPC
Class: |
C23C 18/405 20130101;
C25D 21/12 20130101; C23C 18/31 20130101; C23C 18/1683 20130101;
H01L 21/2885 20130101 |
Class at
Publication: |
205/098 |
International
Class: |
C25D 021/06; C25D
021/16 |
Claims
What is claimed is:
1. A method for preventing foam formation inside a plating cell,
comprising: providing an electrolyte solution to the cell, the
electrolyte solution containing an antifoaming agent, a metal ion
source, and a supporting electrolyte; placing the substrate onto a
substrate holder of the plating apparatus; immersing the substrate
in the electrolyte solution; and depositing the material onto the
substrate.
2. The method of claim 1, further comprising connecting electrical
power to a plurality of electrical contacts disposed to contact the
surface of the substrate after the substrate is placed onto the
substrate holder.
3. The method of claim 1, further comprising monitoring foam
formation inside the plating apparatus and dosing the antifoaming
agent into the electrolyte solution in accordance with a measured
foam thickness.
4. The method of claim 1, wherein the metal ion source is
copper.
5. The method of claim 1, wherein the antifoaming agent is selected
from the group consisting of alcohols, monohydric alcohols,
polyhydric alcohols, octyl alcohol, C.sub.6 to C.sub.20 alcohols,
lauryl alcohol, and combinations and derivatives thereof.
6. The method of claim 1, wherein the antifoaming agent is
dissolved in ethanol.
7. The method of claim 1, wherein the antifoaming agent is
1-octanol dissolved in ethanol.
8. The method of claim 1, wherein the antifoaming agent is at a
final concentration of between about 0.002% and about 10% by volume
in the electrolyte solution.
9. The method of claim 1, wherein one metal ion source comprises a
metal salt selected from the group consisting of copper salt, noble
metal salt, semi-noble metal salt, and combinations thereof.
10. The method of claim 1, wherein the supporting electrolyte
comprise acid and water.
11. A method for preventing foam formation inside an electroless
plating apparatus, comprising: providing an electroless plating
solution containing at least one antifoaming agent; immersing the
substrate in the electroless plating solution; and depositing a
material layer onto the substrate by electroless deposition in the
electroless plating solution.
12. The method of claim 11, wherein the material layer comprises a
catalytic seed layer.
13. The method of claim 12, further comprising depositing a
conductive layer on the substrate over the catalytic seed
layer.
14. The method of claim 11, wherein the material layer comprises a
conductive layer.
15. The method of claim 11, wherein the at least one antifoaming
agent is selected from the group consisting of alcohols, monohydric
alcohols, polyhydric alcohols octyl alcohol, C.sub.6 to C.sub.20
alcohols, lauryl alcohol, hydrophobic oils, amines, alkyl amines,
diamyl methyl amine, amides, acyl derivatives of piperazine,
alkaline earth, sodium stearate, aluminum stearate, hydrophobic
compounds, hydrophobic silica, and combinations and derivatives
thereof.
16. The method of claim 11, wherein the at least one antifoaming
agent is at a final concentration of between about 0.002% and about
10% by volume in the plating electrolyte solution.
17. A method for preventing foam formation inside an electroless
plating apparatus designed for electroless plating on a substrate,
comprising: providing a catalytic layer solution containing at
least one antifoaming agent; immersing the substrate in the
catalytic layer solution; depositing a catalytic seed layer onto
the substrate by electroless deposition in the catalytic layer
solution; and depositing a conductive layer on the substrate over
the catalytic seed layer.
18. The method of claim 17, wherein the conductive layer is
deposited by a deposition technique selected from the group
consisting of physical vapor deposition, chemical vapor deposition,
electrochemical plating, electroless plating, and combinations
thereof.
19. A method for preventing foam formation inside a plating
apparatus designed for plating on a substrate having a metal seed
layer formed thereon, comprising: providing an electrolyte solution
containing at least one antifoaming agent; immersing the substrate
in the electrolyte solution; and depositing a conductive layer onto
the metal seed layer of the substrate.
20. The method of claim 19, further comprising monitoring foam
formation inside the plating apparatus and dosing the antifoaming
agent into the electrolyte solution.
21. The method of claim 19, wherein the at least one antifoaming
agent is selected from the group consisting of alcohols, monohydric
alcohols, polyhydric alcohols octyl alcohol, C.sub.6 to C.sub.20
alcohols, lauryl alcohol, hydrophobic oils, amines, alkyl amines,
diamyl methyl amine, amides, acyl derivatives of piperazine,
alkaline earth, sodium stearate, aluminum stearate, hydrophobic
compounds, hydrophobic silica, and combinations and derivatives
thereof.
22. The method of claim 19, wherein the at least one antifoaming
agent is dissolved in at least one solvent selected from the group
consisting of alcohols, ethanol, siloxanes, polydimethyl siloxane,
and combinations and derivatives thereof, before adding to the
electrolyte solution.
23. The method of claim 19, wherein the at least one antifoaming
agent is at a final concentration of between about 0.002% and about
10% by volume in the electrolyte solution.
24. A composition for a plating bath, comprising: at least one
antifoaming agent selected from the group consisting of alcohols,
monohydric alcohols, polyhydric alcohols octyl alcohol, C6 to C20
alcohols, lauryl alcohol, and combinations and derivatives thereof;
a metal ion source; and a supporting electrolyte.
25. The composition of claim 24, wherein the at least one
antifoaming agent is first dissolved in at least one solvent
selected from the group consisting of alcohols, ethanol, siloxanes,
polydimethyl siloxane, and combinations and derivatives
thereof.
26. The composition of claim 24, wherein the at least one
antifoaming agent is 1-octanol dissolved in ethanol.
27. The composition of claim 24, wherein the at least one
antifoaming agent is at a final concentration of between about
0.002% and about 10% by volume.
28. The composition of claim 24, wherein the at least one metal ion
source comprise a metal salt selected from the group consisting of
copper salt, noble metal salt, semi-noble metal salt, and
combinations thereof.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] Metallization of sub-quarter micron sized features is a
foundational technology for present and future generations of
integrated circuit manufacturing processes. More particularly, in
devices such as ultra large scale integration-type devices, i.e.,
devices having integrated circuits with more than a million logic
gates, the multilevel interconnects that lie at the heart of these
devices are generally formed by filling high aspect ratio, i.e.,
greater than about 4:1, interconnect features with a conductive
material, such as copper. Conventionally, deposition techniques
such as chemical vapor deposition (CVD) and physical vapor
deposition (PVD) have been used to fill these interconnect
features. However, as the interconnect sizes decrease and aspect
ratios increase, void-free interconnect feature fill via
conventional metallization techniques becomes increasingly
difficult. Therefore, plating techniques, i.e., electrochemical
plating (ECP) and electroless plating, have emerged as promising
processes for void free filling of sub-quarter micron sized high
aspect ratio interconnect features in integrated circuit
manufacturing processes.
[0002] In an ECP process, for example, sub-quarter micron sized
high aspect ratio features formed into the surface of a substrate
(or a layer deposited thereon) may be efficiently filled with a
conductive material, such as copper. ECP plating processes are
generally two stage processes, wherein a seed layer is first formed
over the surface features of the substrate (generally through PVD,
CVD, atomic layer deposition (ALD), or other deposition process in
a separate tool), and then the surface features of the substrate
are exposed to an electrolyte solution (in the ECP tool), while an
electrical bias is applied between the seed layer and a copper
anode positioned within the electrolyte solution. The electrolyte
solution is generally rich in copper ions (Cu.sup.2+) that are to
be plated onto the surface of the substrate, and therefore, the
application of the electrical bias, i.e., configuring the substrate
as the cathode, causes these ions to be plated onto the seed layer,
thus depositing a layer of the ions on the substrate surface that
may fill the features.
[0003] Conventional electrochemical and electroless plating cells
utilize various types of substrate immersion processes. However,
immersion processes are prone to generate bubbles on the substrate
surface, which have been shown to cause plating defects, and
therefore, minimization of bubble formation is desirable. Further,
plating processes generally include rotation or agitation of the
substrate in the electrolyte solution, which has been shown to
generate a foam at the electrolyte surface. This foam is also known
to cause plating defects, and as such, should be minimized.
[0004] Therefore, a need exists to provide methods and compositions
for plating processes that are designed to prevent and/or reduce
bubble and/or foam formation.
SUMMARY OF THE INVENTION
[0005] Embodiments of the invention generally provide a method and
formulations for preventing foam formation inside a plating
apparatus prior to or during plating a material on a substrate. In
one embodiment, a method for preventing foam formation inside a
plating apparatus designed for plating a material on a substrate
includes providing an electrolyte solution containing antifoaming
agent, at least one metal ion source, and a supporting electrolyte.
The method further includes placing the substrate onto a substrate
holder of the plating apparatus, immersing the substrate in the
electrolyte solution, and depositing the material onto the
substrate.
[0006] Embodiments of the invention may further provide a method
for preventing foam formation inside a plating apparatus, wherein
the method includes providing an electroless plating solution
containing antifoaming agent, immersing the substrate in the
electroless plating solution, and depositing a material layer onto
the substrate by electroless deposition in the electroless plating
solution. In one aspect of the invention, the material layer
includes a catalytic seed layer. In another aspect of the
invention, the method further includes depositing a conductive
layer on the substrate over the catalytic seed layer. In another
aspect of the invention, the material layer includes a conductive
layer.
[0007] Embodiments of the invention may further provide a method
for preventing foam formation inside an electroless plating
apparatus designed for electroless plating on a substrate includes
providing a catalytic layer solution containing antifoaming agent
and immersing the substrate in the catalytic layer solution. The
method further includes depositing a catalytic seed layer onto the
substrate by electroless deposition in the catalytic layer solution
and depositing a conductive layer on the substrate over the
catalytic seed layer.
[0008] Embodiments of the invention may further provide a method
for preventing foam formation inside a plating apparatus designed
for plating on a substrate having a metal seed layer formed thereon
includes providing an electrolyte solution containing antifoaming
agent. The method further includes immersing the substrate in the
electrolyte solution, and depositing a conductive layer onto the
metal seed layer of the substrate.
[0009] Embodiments of the invention may further provide a
composition for a plating bath that is configured to reduce foam
formation. The composition may include antifoaming agent selected
from the group consisting of alcohols, monohydric alcohols,
polyhydric alcohols, and C.sub.6 to C.sub.20 alcohols, such as
octal and lauryl alcohols, and combinations and derivatives
thereof, at least one metal ion source, and a supporting
electrolyte. Embodiments of the invention further contemplate
omitting the antifoaming agent from the composition and applying
the antifoaming agent to the substrate prior to plating. In this
embodiment, the substrate surface having the pre-wetting
antifoaming agent thereon reduces foam when it contacts the bath,
and further, may slightly accumulate in the bath after several
substrates have been processed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] So that the manner in which the features of the invention
are attained and 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. 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.
[0011] FIGS. 1 is a flow diagram illustrating an exemplary plating
process.
[0012] FIG. 2 is a perspective view of an electroplating system
platform useful to perform electrochemical plating described
herein.
[0013] FIG. 3 is a graphical representation of comparison analyses
using the electrolyte composition of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] The words and phrases used herein should be given their
ordinary and customary meaning by one skilled in the art, unless
otherwise further defined herein.
[0015] Embodiments of the invention include plating methods and
electrolyte compositions configured to reduce, prevent, and/or
eliminate bubbles and/or foam formed in a plating apparatus or on a
substrate. Methods of the invention can include both the chemical
compositions configured to reduce or eliminate bubbles and/or foam,
as well as a method for analyzing electrolyte solutions to
determine if foam has formed or is present on the surface of the
solution. The monitoring process may include in situ analysis of
the plating solution, or alternatively, a sampling of the bath may
be cut therefrom and analyzed separately for the presence of
foam.
[0016] Embodiments of the invention also provide a composition for
presenting and/or removing excess bubbles or foams at the surface
of the substrate without damaging the devices formed on the
substrate surface. A typical composition that can be employed to
prevent or reduce the excess bubbles or foam can include
antifoaming agent, such composition can be used in a plating
process together with an electrolyte solution containing at least
one metal ion source, a supporting electrolyte, and water.
[0017] FIG. 1 is a flow chart illustrating an exemplary method 100
of the invention to prevent and monitor bubble or foam formation in
a plating bath. The method 100 of FIG. 1 includes preparing an
electrolyte solution at step 110, wherein the solution generally
includes an antifoaming agent, a supporting electrolyte, a metal
ion source, and water. The metal ion source may be metal salts
generally required for plating a desired material onto a substrate.
The metal salts may include any of the suitable metal salts for the
material to be plated on the substrate, such as copper salts, noble
metal salts, semi-noble metal salts, Group IV metal salts, etc.
Typical materials to be plated that can be used herein include, but
are not limited to, copper, nickel, gold, silver, and tungsten. The
starting electrolyte solution is thus generally prepared and
pre-mixed before supplying to a plating apparatus.
[0018] The antifoaming agent that can be used herein includes, but
is not limited to, the family of alcohols, such as propanol,
butanol, pentanol, hexanol, heptanol, octanol (octyl alcohol),
monohydric alcohols, polyhydric alcohols, C6 to C20 alcohols,
lauryl alcohol, and any mixtures and derivatives thereof. Other
suitable antifoaming agents that can be used herein include, but
are not limited to, hydrophobic oils, amines, alkyl amines, diamyl
methyl amine, amides, acyl derivatives of piperazine, alkaline
earth, sodium stearate, aluminum stearate, hydrophobic compounds,
hydrophobic silica, and combinations and derivatives thereof.
However, generally speaking, the inventors acknowledge that not all
of the above noted compounds and solutions are amenable to plating
solutions. Currently, the C6 to C20 alcohols are the preferred
antifoaming agents, however, as technology advances, the inventors
acknowledge, and in fact contemplate that the alternative compounds
and solutions that are currently undesirable in a plating solutions
may in fact become practical and preferred.
[0019] In one embodiment, the antifoaming agent may be prepared as
a stock solution before being added into the electrolyte solution.
For example, the antifoaming agent can be dissolved in a solvent at
a concentration of between about 1% and about 50%. The solvent can
be selected from a variety of compounds that, when prepared in a
solution, help to dissolve the antifoaming agent. The compounds
suitable as the solvent for antifoaming agent include, but are not
limited to, alcohols (e.g., ethanol, methanol, etc.), siloxanes,
polydimethyl siloxane, and combinations and derivatives
thereof.
[0020] The antifoaming agent can be added into the electrolyte
solution to a final concentration of between about 0.002% and about
10% by volume, such as between about 0.01% and about 5% by volume,
depending on the antifoaming agent and supporting electrolyte used.
One working example of the antifoaming agent that can be used is at
a final concentration of about 0.01% of 1-octanol in the
electrolyte solution because of its effectiveness and physical
stability. Another example is a stock solution of between about 5%
and about 30% of 1-octanol dissolved in ethanol that can be added
to an electrolyte solution to a final concentration of between
about 0.005% and about 0.25% of 1-octanol in the electrolyte
solution, such as about 0.01% or about 0.05% of 1-octanol in the
electrolyte solution. In general, it is more economical to dissolve
the antifoaming agent into solutions of higher concentration (e.g.,
a stock solution) to be more effective before diluting into a final
electrolyte solution.
[0021] On the other hand, electroless plating may employ multiple
electrolyte solutions and complex components in an electrolyte.
Typical electrolyte components for electroless deposition include,
but are not limited to, noble metal salts, semi-noble metal salts,
other suitable metal salts, complexing agents, additives,
surfactants, stabilizers, and pH adjusting agents. Examples of
noble metals include gold, silver, platinum, palladium, iridium,
rhenium, ruthenium, and osmium. Examples of semi-noble metals
include, iron, cobalt, nickel, copper, and tungsten.
[0022] Various supporting electrolytes for electroplating and
electroless plating, as well as plating apparatuses can be
purchased from Applied Materials, Inc. of Santa Clara, Shipley Inc.
of Marlborough, Mass., CPI International (CPI) of Santa Rosa,
Calif., or Enthone OMI of New Haven, Conn. In one embodiment it is
preferred that the antifoaming agent used does not interact with
the supporting electrolyte components.
[0023] Returning to the method illustrated in FIG. 1, at step 120 a
substrate is placed onto a substrate holder of a plating apparatus
configured to use the prepared electrolyte discussed above. Step
120 also includes connecting electrical power to a plurality of
electrical contacts positioned in communication with the substrate
and immersing the substrate in the electrolyte solution. A negative
voltage is then applied to the substrate or the seed layer
deposited thereon during the immersion to prevent etching on the
surface of the substrate (e.g., the side walls of vias and
trenches) by of the plating electrolyte solution. In general, the
antifoaming agent in the electrolyte solution is designed to
prevent bubble and foam formation on the surface of the electrolyte
solution, which is known to adhere to the plating surface and cause
defects. The electrolyte solution containing the antifoaming agent
results in reduced propensity of the electrolyte solution to create
and/or sustain bubbles that can be trapped against the surface of
the substrate. The reduction in the number and size of bubbles
reduces the number of defects typically found on the substrate
after plating.
[0024] At step 130, a material is deposited on the substrate by an
electrochemical deposition process, for example, by use of an
electrolyte solution. Agitating the electrolyte solution inside the
plating apparatus is generally employed and one of the advantages
of the antifoaming agent to be included herein in the electrolyte
solution is to prevent bubble or foam formation during such
agitation process, by, for example, rotating the wafer.
[0025] At step 140, an optional step is performed to monitor bubble
or foam formation inside the plating apparatus. For example,
precision monitoring equipment may be used to determine the
presence and/or thickness of a foam layer on the surface of a
plating bath, as the foam thickness generally has a thickness on
the order of a monolayer. The measurement may be made in situ, or
alternatively, a sample of the solution may be taken from near the
surface of the bath and then analyzed in a separate analyzer. The
determination that foam is present can be used to dispense
additional antifoaming agents into the bath, or possibly to
determine when the useful life of the bath has been reached when
form forms with the antifoaming agent already contained in the
bath. Regardless, at step 150 the substrate may be removed from the
cell.
[0026] Electroless plating involves an auto-catalyzed chemical
deposition process that requires a surface capable of electron
transfer for subsequent deposition and nucleation of a conductive
material, such as a catalytic layer containing noble metals,
semi-noble metals, and alloys thereof. Noble metals and semi-noble
metals are not readily oxidized, and thus provide a surface capable
of electron transfer. However, trapped gas and other bubbles, such
as hydrogen gas, are formed in the catalytic layer during an
electroless deposition process.
[0027] Therefore, in one embodiment of the invention, a method is
provided for preventing foam formation during electroless
deposition of a catalytic layer. The method generally includes the
insertion of the substrate into an electroless plating apparatus,
dispensing a catalytic layer solution, removing the catalytic layer
solution, then rinsing with water or other rinsing solutions. For
example, the method may include contacting the substrate with an
aqueous catalytic layer solution containing Group IV metal ions,
such as tin ions, and then contacting the substrate with another
aqueous catalytic layer solution containing noble metal ions,
semi-noble metal ions, or combinations thereof. The catalytic layer
solution may generally include antifoaming agent as described
herein to prevent foam formation and remove entrapped gas, such as
hydrogen gas, formed during electroless deposition. Thus, a
catalytic seed layer is deposited onto the substrate by electroless
deposition in the catalytic layer solution.
[0028] In another embodiment of the invention, a method is provided
for preventing foam formation during electroless deposition of a
conductive layer. The method generally includes the insertion of
the substrate into an electroless plating apparatus, dispensing an
electroless plating solution, then removing the electroless
solution, then rinsing the substrate with water or other rinsing
solutions, and removing the substrate from the electroless plating
apparatus. In general, an electroless electrolyte solution
containing antifoaming agent and other various chemical
constituents required for electroless deposition is prepared before
placing the substrate onto the substrate holder of the electroless
plating apparatus and having the electroless electrolyte solution
supplied on the surface of the substrate. Such electroless plating
solution for a conductive layer may include, but is not limited to,
metal salts for the material of the conductive layer, other
suitable salts, complexing agents, additives, stabilizers, reducing
agents, and pH adjusters. For example, an exemplary electroless
plating solution includes copper sulfate,
ethylenediaminetetraacetic acid (EDTA) as a complexing agent,
formaldehyde (HCHO) as the reducing agent, and sodium hydroxide to
adjust the pH of the electroless plating solution. A discussion of
an exemplary electroless deposition process is described in the
co-pending U.S. patent application Ser. No. 10/059,822, entitled
"Electroless Deposition Method Over Sub-Micron Apertures", filed on
Jan. 28, 2002, which is incorporated by reference herein.
[0029] A chemical reaction among the principal components of an
electroless deposition process for a conductive layer typically
generates gases, such as hydrogen gas. It is believed that the use
of antifoaming agent as described herein helps to remove trapped
hydrogen gas formed in the conductive layer during the deposition
process and thus prevents defect formation on the substrate.
[0030] Plating System:
[0031] Embodiments of the invention provide a plating method and
compositions that can be performed in various plating systems. One
example of an electrochemical plating system that may be used
herein is an Electra integrated Electro-Chemical Plating (iECP)
System available from Applied Materials, Inc., of Santa Clara,
Calif. Another example is an ELECTRA CU.TM. ECP platform, available
from Applied Materials, Inc. of Santa Clara, Calif. The
electroplating apparatus is more fully described in U.S. patent
application Ser. No. 09/289,074, entitled "Electro-Chemical
Deposition System" filed Apr. 8, 1999, which is incorporated by
reference herein. In addition, any system enabling electrochemical
processing using the analytical methods or techniques described
herein may also be used. Another example of a suitable plating
apparatus is disclosed in U.S. patent application Ser. No.
10/268,284, entitled, "Electrochemical Processing Cell", filed on
Oct. 9, 2002, which is incorporated by reference herein. A
discussion of an exemplary electroless deposition system is
described in the co-pending U.S. patent application Ser. No.
10/059,572, entitled "Electroless Deposition Apparatus", filed on
Jan. 24, 2002, is also incorporated by reference herein.
[0032] FIG. 2 is a perspective view of an electroplating system
platform 200 of the invention. The electroplating system platform
200 generally includes a mainframe 214 having a mainframe substrate
transfer robot, a loading station 210 disposed in connection with
the mainframe 214, one or more processing cells 240 disposed in
connection with the mainframe, a spin-rinse-dry (SRD) station 212,
and an electrolyte replenishing system 220 fluidly connected to the
one or more electrical processing cells 240. Additionally, the
electroplating system platform 200 is enclosed in a clean
environment using panels, such as plexiglass panels.
[0033] The mainframe 214 generally includes a mainframe transfer
station 216 and a plurality of processing stations 218. Each
processing station 218 includes one or more processing cells 240.
An electrolyte replenishing system 220 is positioned adjacent the
electroplating system platform 200 and connected to the process
cells 240 individually to circulate electrolyte used for the
electroplating process. The electroplating system platform 200 also
includes a control system 222, typically a programmable
microprocessor. The control system 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
electroplating system platform 200.
[0034] The loading station 210 typically 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 orientor 230 included in the
loading station 210 can be configured according to the desired
throughput of the system. A substrate cassette containing
substrates is loaded onto the substrate cassette receiving area 224
to introduce substrates into the electroplating system platform.
The substrate orientor 230 positions each substrate in a desired
orientation to ensure that each substrate is properly processed.
The loading station transfer robot 228 transfers substrates between
the substrate cassette and the substrate orientor 230. The loading
station transfer robot 228 also transfers substrates between the
loading station 210 and the SRD station 212.
[0035] The electroplating process cell 240 generally includes a
head assembly, a process kit and an electrolyte collector. The head
assembly includes a substrate holder assembly having a substrate
holder 264 and a cathode contact ring. The head assembly is
provided to position the substrate in a processing position and in
a substrate loading position. In one embodiment, the head assembly
is a rotatable head assembly having a rotational actuator disposed
and attached to the head assembly to rotate the head assembly
during substrate processing.
[0036] In another embodiment, the electrolyte replenishing system
220 includes one or more degasser modules adapted to remove
undesirable gases from the electrolyte. The degasser module
generally includes 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 are preferably
placed in line on the electrolyte supply line adjacent to the
process cells 240. The degasser modules are preferably positioned
as close as possible to the process cells 240 so that most of the
gases from the electrolyte replenishing system are removed by the
degasser modules before the electrolyte enters the process cells.
The degasser modules can be placed at many other alternative
positions. A commercially available degasser module is available
from Millipore Corporation, located in Bedford, Mass.
EXAMPLE
[0037] Examples of reducing, preventing, and/or eliminating foam
formation using the electrolyte compositions as described above are
presented herein. Typical concentrations of the electrolyte that
may be used are as follows. The concentrations of the inorganic
components may be, for example, between about 5 grams per liter
(g/L) to about 80 g/L of copper sulfate, such as between about 10
g/L and about 60 g/L, between about 30 ppm and about 200 ppm of
hydrochloric acid, and between about 5 g/L to about 200 g/L of
sulfuric acid. The concentrations of the organic components in a
plating bath that can be analyzed/measured by the CVS, titration,
and other methods known in the semiconductor art, and may be
present at concentrations of between about 0.1% to about 2.5% by
volume of an accelerator, brightener, or anti-suppressor, between
about 0.1% and about 6% by volume of a suppressor, carrier,
surfactant, or wetting agent, and between about 0.1% to about 2% by
volume of a leveler, over-plate inhibitor, or grain refiner.
Various components (both hardware and chemicals) used herein were
purchased from Applied materials, Inc. of Santa Clara, Shipley Inc.
of Marlborough, Mass., CPI International (CPI) of Santa Rosa,
Calif., or Enthone OMI of New Haven, Conn.
[0038] FIG. 3 demonstrates the effect of various concentrations of
an antifoaming agent on foam formation. Foam thickness is plotted
against various concentrations of 1-octanol (dissolved in ethanol
first). Two different supporting electrolytes, i.e., a 2 component
electrolyte and a 3 component electrolyte, with one shown as solid
squares and the other shown as solid diamond in FIG. 3, are
compared in the absence (zero concentration of antifoaming agent)
and presence of the added antifoaming agent. Generally, the foam
height drops as the antifoaming agent is added. In FIG. 3, the
effective concentration of the antifoaming agent is different for
the two supporting electrolytes used. Thus, best antifoaming effect
can be achieved at a minimum concentration of about 0.01% of the
antifoaming agent in one supporting electrolyte (solid square) and
at a minimum concentration of about 0.016% of the same antifoaming
agent used in another supporting electrolyte (solid diamond).
[0039] While the foregoing is directed to various embodiments of
the invention, other and further embodiments of the invention may
be devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
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