U.S. patent application number 10/845754 was filed with the patent office on 2004-12-09 for method and composition for fine copper slurry for low dishing in ecmp.
Invention is credited to Chen, Liang-Yuh, Hu, Yongqi, Liu, Feng Q., Tsai, Stan D..
Application Number | 20040248412 10/845754 |
Document ID | / |
Family ID | 33493108 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040248412 |
Kind Code |
A1 |
Liu, Feng Q. ; et
al. |
December 9, 2004 |
Method and composition for fine copper slurry for low dishing in
ECMP
Abstract
A method of processing a substrate having a conductive material
layer disposed thereon is provided which includes positioning the
substrate in a process apparatus and supplying a first polishing
composition between to the substrate. The polishing composition
comprises phosphoric acid, at least one chelating agent, a
corrosion inhibitor, a salt, an oxidizer, abrasive particulates, at
least one pH adjusting agent to provide a pH from about 4 to about
7 and a solvent. The method further includes forming a passivation
layer on the conductive material layer, abrading the passivation
layer to expose a portion of the conductive material layer,
applying a first bias to the substrate, and removing at least about
50% of the conductive material layer. The method further includes
separating the substrate from the first polishing composition,
exposing the substrate to a second polishing composition and a
second bias, and continuing to remove the conductive material
layer.
Inventors: |
Liu, Feng Q.; (San Jose,
CA) ; Tsai, Stan D.; (Fremont, CA) ; Hu,
Yongqi; (San Jose, CA) ; Chen, Liang-Yuh;
(Foster City, CA) |
Correspondence
Address: |
Applied Materials
Patent Counsel - Legal Affairs Department
P.O. Box 450A
Santa Clara
CA
95052
US
|
Family ID: |
33493108 |
Appl. No.: |
10/845754 |
Filed: |
May 14, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10845754 |
May 14, 2004 |
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10608404 |
Jun 26, 2003 |
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10845754 |
May 14, 2004 |
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10456220 |
Jun 6, 2003 |
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Current U.S.
Class: |
438/689 ;
257/E21.583 |
Current CPC
Class: |
H01L 21/7684 20130101;
B23H 5/08 20130101; H01L 21/3212 20130101; B24B 37/0056 20130101;
C25F 3/02 20130101; B23H 3/08 20130101; C09G 1/04 20130101; B24B
37/044 20130101; H01L 21/32134 20130101; H01L 21/32125 20130101;
B24B 37/046 20130101 |
Class at
Publication: |
438/689 |
International
Class: |
H01L 021/4763; H01L
021/302; H01L 021/461 |
Claims
1. A method of processing a substrate having a conductive material
layer disposed thereon, comprising: positioning the substrate in a
process apparatus; exposing the substrate to a first polishing
composition; applying a first bias to the substrate; removing at
least 50% of the conductive material layer; exposing the substrate
to a second polishing composition and a second bias; and continuing
to remove the conductive material layer.
2. The method of claim 1, wherein the first polishing composition
comprises phosphoric acid, at least one chelating agent, a
corrosion inhibitor, a salt, an oxidizer, and abrasive
particulates.
3. The method of claim 1, wherein the conductive material layer
comprises copper or a copper alloy.
4. The method of claim 3, wherein applying the first bias removes
at least about 80% of the conductive material layer.
5. The method of claim 3, wherein the second polishing composition
comprises: from about 0.1 wt % to about 5 wt % of phosphoric acid;
from about 0.1 wt % to about 5 wt % of at least one chelating
agent; and from about 0.01 wt % to about 1 wt % of the corrosion
inhibitor.
6. The method of claim 5, wherein the at least one chelating agent
of the second polishing composition is selected from the group
consisting of glycine, ethylenediamine, ethylenediamine
tetraacetate, citric acid, ammonium citrate, salts thereof,
derivatives thereof, and combinations thereof.
7. The method of claim 6, wherein the corrosion inhibitor of the
second polishing composition is selected from the group consisting
of benzotriazole, 5-methyl-1-benzotriazole, salts thereof,
derivatives thereof, and combinations thereof.
8. The method of claim 7, wherein the corrosion inhibitor of the
second polishing composition is benzotriazole and the at least one
chelating agent of the second polishing composition is glycine.
9. The method of claim 7, wherein the corrosion inhibitor of the
second polishing composition is benzotriazole and the at least one
chelating agent of the second polishing composition is
ethylenediamine and ammonium citrate.
10. The method of claim 9, wherein the second polishing composition
further comprises polyethylene glycol.
11. The method of claim 7, wherein the second polishing composition
further comprises at least one member selected from the group
consisting of abrasive particulates, hydrogen peroxide, derivatives
thereof, and combinations thereof.
12. The method of claim 11, wherein the second polishing
composition comprises at least one pH adjusting agent to provide a
pH from about 4 to about 7 and a solvent.
13. The method of claim 2, wherein the first polishing composition
has a conductivity in a range from about 30 mS to about 60 mS.
14. The method of claim 13, wherein the second polishing
composition has a conductivity in a range from about 15 mS to about
40 mS.
15. The method of claim 14, wherein the first polishing composition
comprises: from about 1 wt % to about 10 wt % of phosphoric acid;
from about 0.1 wt % to about 6 wt % of the at least one chelating
agent; from about 0.01 wt % to about 1 wt % of the corrosion
inhibitor; from about 0.5 wt % to about 10 wt % of the salt; from
about 0.2 wt % to about 5 wt % of the oxidizer; and from about 0.05
wt % to about 1 wt % of the abrasive particulates.
16. A method of processing a substrate having a conductive material
layer disposed thereon, comprising: positioning the substrate in a
process apparatus; exposing the substrate to a first polishing
composition comprising phosphoric acid, at least one chelating
agent, a corrosion inhibitor, a salt, an oxidizer, and abrasive
particulates; applying a first bias to the substrate; removing at
least 50% of the conductive material layer; exposing the substrate
to a second polishing composition and a second bias; and continuing
to remove the conductive material layer.
17. The method of claim 16, wherein the conductive material layer
comprises copper or a copper alloy.
18. The method of claim 16, wherein applying the first bias removes
at least about 80% of the conductive material layer.
19. The method of claim 17, wherein the second polishing
composition comprises: from about 0.1 wt % to about 5 wt % of
phosphoric acid; from about 0.1 wt % to about 5 wt % of at least
one chelating agent; and from about 0.01 wt % to about 1 wt % of
the corrosion inhibitor.
20. The method of claim 19, wherein the at least one chelating
agent of the second polishing composition is selected from the
group consisting of glycine, ethylenediamine, ethylenediamine
tetraacetate, citric acid, ammonium citrate, salts thereof,
derivatives thereof, and combinations thereof.
21. The method of claim 20, wherein the corrosion inhibitor of the
second polishing composition is selected from the group consisting
of benzotriazole, 5-methyl-1-benzotriazole, salts thereof,
derivatives thereof, and combinations thereof.
22. The method of claim 21, wherein the corrosion inhibitor of the
second polishing composition is benzotriazole and the at least one
chelating agent of the second polishing composition is glycine.
23. The method of claim 21, wherein the corrosion inhibitor of the
second polishing composition is benzotriazole and the at least one
chelating agent of the second polishing composition is
ethylenediamine and ammonium citrate.
24. The method of claim 23, wherein the second polishing
composition further comprises polyethylene glycol.
25. The method of claim 21, wherein the second polishing
composition further comprises at least one member selected from the
group consisting of abrasive particulates, hydrogen peroxide,
derivatives thereof, and combinations thereof.
26. The method of claim 25, wherein the second polishing
composition comprises at least one pH adjusting agent to provide a
pH from about 4 to about 7 and a solvent.
27. The method of claim 17, wherein the first polishing composition
has a conductivity in a range from about 30 mS to about 60 mS.
28. The method of claim 19, wherein the second polishing
composition has a conductivity in a range from about 15 mS to about
40 mS.
29. The method of claim 27, wherein the first polishing composition
comprises: from about 1 wt % to about 10 wt % of phosphoric acid;
from about 0.1 wt % to about 6 wt % of the at least one chelating
agent; from about 0.01 wt % to about 1 wt % of the corrosion
inhibitor; from about 0.5 wt % to about 10 wt % of the salt; from
about 0.2 wt % to about 5 wt % of the oxidizer; and from about 0.05
wt % to about 1 wt % of the abrasive particulates.
30. A method of processing a substrate having a conductive material
layer disposed thereon, comprising: positioning the substrate in a
process apparatus comprising a first electrode and a second
electrode; supplying a first polishing composition between the
first electrode and the substrate, wherein the polishing
composition comprises phosphoric acid, at least one chelating
agent, a corrosion inhibitor, a salt, an oxidizer, abrasive
particulates, at least one pH adjusting agent to provide a pH from
about 4 to about 7, and a solvent; forming a passivation layer on
the conductive material layer; abrading the passivation layer to
expose a portion of the conductive material layer; applying a first
bias between the first electrode and the second electrode; removing
at least about 50% of the conductive material layer; separating the
substrate from the first polishing composition; exposing the
substrate to a second polishing composition and a second bias; and
continuing to remove the conductive material layer.
31. The method of claim 30, wherein the conductive material layer
comprises copper or a copper alloy.
32. The method of claim 31, wherein applying the first bias removes
at least about 80% of the conductive material layer.
33. The method of claim 31, wherein the second polishing
composition comprises: from about 0.1 wt % to about 5 wt % of
phosphoric acid; from about 0.1 wt % to about 5 wt % of at least
one chelating agent; and from about 0.01 wt % to about 1 wt % of
the corrosion inhibitor.
34. The method of claim 33, wherein the at least one chelating
agent of the second polishing composition is selected from the
group consisting of glycine, ethylenediamine, ethylenediamine
tetraacetate, citric acid, ammonium citrate, salts thereof,
derivatives thereof, and combinations thereof.
35. The method of claim 34, wherein the corrosion inhibitor of the
second polishing composition is selected from the group consisting
of benzotriazole, 5-methyl-1-benzotriazole, salts thereof,
derivatives thereof, and combinations thereof.
36. The method of claim 35, wherein the corrosion inhibitor of the
second polishing composition is benzotriazole and the at least one
chelating agent of the second polishing composition is glycine.
37. The method of claim 35, wherein the corrosion inhibitor of the
second polishing composition is benzotriazole and the at least one
chelating agent of the second polishing composition is
ethylenediamine and ammonium citrate.
38. The method of claim 37, wherein the second polishing
composition further comprises polyethylene glycol.
39. The method of claim 35, wherein the second polishing
composition further comprises at least one member selected from the
group consisting of abrasive particulates, hydrogen peroxide,
derivatives thereof and combinations thereof.
40. The method of claim 39, wherein the second polishing
composition comprises at least one pH adjusting agent to provide a
pH from about 4 to about 7 and a solvent.
41. The method of claim 31, wherein the first polishing composition
has a conductivity in a range from about 30 mS to about 60 mS.
42. The method of claim 33, wherein the second polishing
composition has a conductivity in a range from about 15 mS to about
40 mS.
43. The method of claim 41, wherein the first polishing composition
comprises: from about 1 wt % to about 10 wt % of phosphoric acid;
from about 0.1 wt % to about 6 wt % of the at least one chelating
agent; from about 0.01 wt % to about 1 wt % of the corrosion
inhibitor; from about 0.5 wt % to about 10 wt % of the salt; from
about 0.2 wt % to about 5 wt % of the oxidizer; and from about 0.05
wt % to about 1 wt % of the abrasive particulates.
44. A method of processing a substrate having a conductive material
layer disposed thereon, comprising: providing the substrate to a
process apparatus; exposing the substrate to a first polishing
composition, wherein the first polishing composition comprises:
from about 1 wt % to about 10 wt % of phosphoric acid; from about
0.1 wt % to about 6 wt % of at least one chelating agent; from
about 0.01 wt % to about 1 wt % of a corrosion inhibitor; from
about 0.5 wt % to about 10 wt % of a salt; from about 0.2 wt % to
about 5 wt % of an oxidizer; from about 0.05 wt % to about 1 wt %
of an abrasive particulates; at least one pH adjusting agent to
provide a pH from about 4 to about 7; and a solvent; applying a
first bias to the substrate; removing at least 50% of the
conductive material layer; and exposing the substrate to a second
polishing composition and a second bias to continue removing the
conductive layer, wherein the second polishing composition
comprises: about 0.1 wt % to about 5 wt % of phosphoric acid; from
about 0.1 wt % to about 5 wt % of at least one chelating agent; and
from about 0.01 wt % to about 1 wt % of the corrosion
inhibitor.
45. The method of claim 44, wherein the conductive material layer
comprises copper or a copper alloy.
46. The method of claim 45, wherein applying the first bias removes
at least about 80% of the conductive material layer.
47. The method of claim 44, wherein the at least one chelating
agent of the second polishing composition is selected from the
group consisting of glycine, ethylenediamine, ethylenediamine
tetraacetate, citric acid, ammonium citrate, salts thereof,
derivatives thereof, and combinations thereof.
48. The method of claim 47, wherein the corrosion inhibitor of the
second polishing composition is selected from the group consisting
of benzotriazole, 5-methyl-1-benzotriazole, salts thereof,
derivatives thereof, and combinations thereof.
49. The method of claim 48, wherein the corrosion inhibitor of the
second polishing composition is benzotriazole and the at least one
chelating agent of the second polishing composition is
ethylenediamine and ammonium citrate.
50. The method of claim 48, wherein the corrosion inhibitor of the
second polishing composition is benzotriazole and the at least one
chelating agent of the second polishing composition is glycine.
51. The method of claim 50, wherein the second polishing
composition further comprises polyethylene glycol.
52. The method of claim 48, wherein the second polishing
composition further comprises at least one member selected from the
group consisting of abrasive particulates, hydrogen peroxide,
derivatives thereof, and combinations thereof.
53. The method of claim 52, wherein the second polishing
composition comprises at least one pH adjusting agent to provide a
pH from about 4 to about 7 and a solvent
54. The method of claim 45, wherein the first polishing composition
has a conductivity in a range from about 30 mS to about 60 mS.
55. The method of claim 47, wherein the second polishing
composition has a conductivity in a range from about 15 mS to about
40 mS.
56. A method of processing a substrate having a conductive material
layer disposed thereon, comprising: positioning the substrate in a
process apparatus; exposing the substrate to a first polishing
composition with a first conductivity in a range from about 30 mS
to about 60 mS and comprising an oxidizer and abrasive
particulates; applying a first bias to the substrate; exposing the
substrate to a second polishing composition with a second
conductivity in a range from about 15 mS to about 40 mS; applying a
second bias to the substrate; and continuing to remove the
conductive layer.
57. A method of processing a substrate having a conductive material
layer disposed thereon, comprising: positioning the substrate in a
process apparatus; exposing the substrate to a first polishing
composition comprising phosphoric acid, at least one chelating
agent, a corrosion inhibitor, a salt, an oxidizer, abrasive
particulates, at least one pH adjusting agent to provide a pH from
about 4 to about 7, and a solvent; applying a first bias to the
substrate; exposing the substrate to a second polishing composition
comprising phosphoric acid, at least one chelating agent, a
corrosion inhibitor, abrasive particulates, at least one pH
adjusting agent to provide a pH from about 4 to about 7, and a
solvent; applying a second bias to the substrate; and continuing to
remove the conductive layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
U.S. patent application Ser. No. 10/608,404, filed Jun. 26, 2003,
entitled "Method and Composition for Polishing a Substrate," and is
also a continuation-in-part of co-pending U.S. patent application
Ser. No. 10/456,220, filed Jun. 6, 2003, entitled "Method and
Composition for Polishing a Substrate," which are both incorporated
by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention relate to compositions
and methods for removing a conductive material from a
substrate.
[0004] 2. Background of the Related Art
[0005] Reliably producing sub-half micron and smaller features is
one of the key technologies for the next generation of very large
scale integration (VLSI) and ultra large-scale integration (ULSI)
of semiconductor devices. However, as the limits of circuit
technology are pushed, the shrinking dimensions of interconnects in
VLSI and ULSI technology have placed additional demands on
processing capabilities. Reliable formation of interconnects is
important to VLSI and ULSI success and to the continued effort to
increase circuit density and quality of individual substrates and
die.
[0006] Multilevel interconnects are formed using sequential
material deposition and material removal techniques on a substrate
surface to form features therein. As layers of materials are
sequentially deposited and removed, the uppermost surface of the
substrate may become non-planar across its surface and require
planarization prior to further processing. Planarization or
"polishing" is a process where material is removed from the surface
of the substrate to form a generally even, planar surface.
Planarization is useful in removing excess deposited material,
removing undesired surface topography, and surface defects, such as
surface roughness, agglomerated materials, crystal lattice damage,
scratches and contaminated layers or materials to provide an even
surface for subsequent photolithography and other semiconductor
processes.
[0007] Chemical mechanical planarization or chemical mechanical
polishing (CMP) is a common technique used to planarize substrates.
In conventional CMP techniques, a substrate carrier or polishing
head is mounted on a carrier assembly and positioned in contact
with a polishing article in a CMP apparatus. The carrier assembly
provides a controllable pressure to the substrate urging the
substrate against the polishing pad. The pad is moved relative to
the substrate by an external driving force. Thus, the CMP apparatus
effects polishing or rubbing movement between the surface of the
substrate and the polishing article while dispersing a polishing
composition to effect both chemical activity and mechanical
activity.
[0008] However, materials deposited on the surface of a substrate
to fill feature definitions formed therein often result in unevenly
formed surfaces over feature definitions of variable density.
Referring to FIG. 1A, a metal layer 20 is deposited on a substrate
10 to fill wide feature definitions 30, also known as low density
feature definitions, or narrow feature definitions 40, also known
as and high density feature definitions. Excess material, called
overburden, may be formed with a greater thickness 45 over the
narrow feature definitions 40 and may have minimal deposition 35
over wide feature definitions 30. Polishing of surfaces with
overburden may result in the retention of residues 50 from
inadequate metal removal over narrow features. Overpolishing
processes to remove such residues 50 may result in excess metal
removal over wide feature definitions 30. Excess metal removal can
form topographical defects, such as concavities or depressions
known as dishing 55, over wide features, as shown in FIG. 1B.
[0009] Dishing of features and retention of residues on the
substrate surface are undesirable since dishing and residues may
detrimentally affect subsequent processing of the substrate. For
example, dishing results in a non-planar surface that impairs the
ability to print high-resolution lines during subsequent
photolithographic steps and detrimentally affects subsequent
surface topography of the substrate, which affects device formation
and yields. Dishing also detrimentally affects the performance of
devices by lowering the conductance and increasing the resistance
of the devices, causing device variability and device yield loss.
Residues may lead to uneven polishing of subsequent materials, such
as barrier layer materials (not shown) disposed between the
conductive material and the substrate surface. Post CMP profiles
generally show higher dishing on wide trenches than on narrow
trenches or dense areas. Uneven polishing will also increase defect
formation in devices and reduce substrate yields.
[0010] Also, substrate polishing processes must be very efficient
to increase the throughput production. Often, defects are formed on
substrates that are over polished due to an increase in process
variables, such as chemical concentrations, electrical potentials
and/or pressure of polishing articles. Some of these defects may be
minimized by decreasing these variables, but with an increase of
time and loss of throughput production.
[0011] Therefore, there is a need for compositions and methods for
removing conductive material from a substrate that minimizes damage
to the substrate during planarization, as well as minimizes time
for production.
SUMMARY OF THE INVENTION
[0012] In one embodiment, a method of processing a substrate having
a conductive material layer disposed thereon is provided which
includes positioning the substrate in a process apparatus and
supplying a first polishing composition to the substrate. The
polishing composition comprises phosphoric acid, at least one
chelating agent, a corrosion inhibitor, a salt, an oxidizer,
abrasive particulates, at least one pH adjusting agent to provide a
pH from about 4 to about 7, and a solvent. The method further
includes forming a passivation layer on the conductive material
layer, abrading the passivation layer to expose a portion of the
conductive material layer, applying a first bias to the substrate,
and removing at least about 50% of the conductive material layer.
The method further includes separating the substrate from the first
polishing composition, exposing the substrate to a second polishing
composition and a second bias, and continuing to remove the
conductive material layer.
[0013] In another embodiment, a method of processing a substrate
having a conductive material layer disposed thereon is provided
which includes positioning the substrate on a process apparatus and
exposing the substrate to a first polishing composition comprising
phosphoric acid, at least one chelating agent, a corrosion
inhibitor, a salt, an oxidizer and abrasive particulates. The
method further includes applying a first bias to the substrate,
removing at least 50% of the conductive material layer, exposing
the substrate to a second polishing composition and a second bias
and continuing to remove the conductive material layer.
[0014] In another embodiment, a method of removing a conductive
material layer is provided which includes providing the substrate
to a process apparatus and exposing the substrate to a first
polishing composition. The first polishing composition comprises
from about 1 wt % to about 10 wt % of phosphoric acid, from about
0.1 wt % to about 6 wt % of at least one chelating agent, from
about 0.01 wt % to about 1 wt % of a corrosion inhibitor, from
about 0.5 wt % to about 10 wt % of a salt, from about 0.2 wt % to
about 5 wt % of an oxidizer, from about 0.05 wt % to about 1 wt %
of an abrasive particulates, at least one pH adjusting agent to
provide a pH from about 4 to about 7, and a solvent. The method
further includes applying a first bias to the substrate, removing
at least 50% of the conductive material layer, and exposing the
substrate to a second polishing composition and a second bias to
continue removing the conductive layer. The second polishing
composition comprises about 0.1 wt % to about 5 wt % of phosphoric
acid, from about 0.1 wt % to about 5 wt % of at least one chelating
agent, and from about 0.01 wt % to about 1 wt % of the corrosion
inhibitor.
[0015] In another embodiment, a method of processing a substrate
having a conductive material layer disposed thereon is provided
which includes positioning the substrate in a process apparatus,
exposing the substrate to a first polishing composition with a
first conductivity in a range from about 30 milliSiemens (mS) to
about 60 mS, the first polishing composition comprising an oxidizer
and abrasive particulates, and applying a first bias to the
substrate. The method further includes exposing the substrate to a
second polishing composition with a second conductivity in a range
from about 15 mS to about 40 mS, and applying a second bias to the
substrate to continue removing the conductive layer.
[0016] In another embodiment, a method of processing a substrate
having a conductive material layer disposed thereon is provided
which includes positioning the substrate in a process apparatus,
exposing the substrate to a first polishing composition, and
applying a first bias to the substrate. The first polishing
composition includes phosphoric acid, at least one chelating agent,
a corrosion inhibitor, a salt, an oxidizer, abrasive particulates,
at least one pH adjusting agent to provide a pH from about 4 to
about 7, and a solvent. The process further includes exposing the
substrate to a second polishing composition, applying a second bias
to the substrate, and continues removing the conductive layer. The
second polishing composition comprises phosphoric acid, at least
one chelating agent, a corrosion inhibitor, abrasive particulates,
at least one pH adjusting agent to provide a pH from about 4 to
about 7, and a solvent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] So that the manner in which the above recited aspects of the
present invention are attained and can be understood in detail, a
more particular description of embodiments of the invention,
briefly summarized above, may be had by reference to the
embodiments thereof which are illustrated in the appended
drawings.
[0018] 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.
[0019] FIGS. 1A-1B are schematic cross-sectional views illustrating
a polishing process performed on a substrate according to
conventional processes;
[0020] FIG. 2 is a plan view of one embodiment of a processing
apparatus of the invention;
[0021] FIG. 3 is a cross-sectional view of one embodiment of a
polishing process station; and
[0022] FIGS. 4A-4D are schematic cross-sectional views illustrating
a polishing process performed on a substrate according to one
embodiment for planarizing a substrate surface described
herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0023] In general, aspects of the inventions provide compositions
and methods for removing at least a conductive material from a
substrate surface. The inventions are described below in reference
to a planarizing process for the removal of conductive materials
from a substrate surface by an electrochemical mechanical polishing
(ECMP) technique.
[0024] The words and phrases used herein should be given their
ordinary and customary meaning in the art by one skilled in the art
unless otherwise further defined. Chemical mechanical polishing
should be broadly construed and includes, but is not limited to,
planarizing a substrate surface using chemical activity and
mechanical activity, or a concurrent application of chemical
activity and mechanical activity. Electropolishing should be
broadly construed and includes, but is not limited to, removing
material from a substrate by eroding the substrate surface under
application of current. Electrochemical mechanical polishing (ECMP)
should be broadly construed and includes, but is not limited to,
planarizing a substrate by the application of electrochemical
activity, mechanical activity, chemical activity, or a concurrent
application of a combination of electrochemical, chemical, and/or
mechanical activity to remove material from a substrate
surface.
[0025] Anodic dissolution should be broadly construed and includes,
but is not limited to, the application of an anodic bias to a
substrate directly or indirectly which results in the removal of
conductive material from a substrate surface and into a surrounding
polishing composition. Polishing composition should be broadly
construed and includes, but is not limited to, a composition that
provides ionic conductivity, and thus, electrical conductivity, in
a liquid medium, which generally comprises materials known as
electrolyte components. The amount of each electrolyte component in
polishing compositions can be measured in volume percent or weight
percent. Volume percent refers to a percentage based on volume of a
desired liquid component divided by the total volume of all of the
liquid in the complete composition. A percentage based on weight
percent is the weight of the desired component divided by the total
weight of all of the liquid components in the complete composition.
Abrading and abrasion should be broadly construed and includes, but
is not limited to, contacting a material and displacing,
disturbing, or removing all or a portion of a material.
[0026] The electrochemical mechanical polishing process may be
performed in a process apparatus, such as a platform having one or
more polishing stations adapted for electrochemical mechanical
polishing processes. A platen for performing an electrochemical
mechanical polishing process may include a polishing article, a
first electrode, and a second electrode, wherein the substrate is
in electrical contact with the second electrode. A first
electrochemical mechanical polishing process may be performed on a
first platen as described herein and the second electrochemical
mechanical polishing process may be performed on the same or
different platen adapted for electrochemical mechanical polishing,
such as the second platen as described herein.
[0027] One Apparatus Embodiment
[0028] FIG. 2 depicts an electrochemical processing apparatus 100
having at least two electrochemical mechanical polishing (ECMP)
stations 102 and 103. Optionally, as depicted in the embodiment
shown in FIG. 2, the system 100 may include at least one
conventional polishing station 106, such as a chemical mechanical
polishing (CMP) station, disposed adjacent the ECMP station 103 on
a single platform or tool. In one embodiment, polishing station 106
is a third ECMP station. One polishing tool that may be adapted to
benefit from the invention is a REFLEXION.RTM. chemical mechanical
polisher available from Applied Materials, Inc. located in Santa
Clara, Calif. Examples of other polishing tools that may be adapted
to benefit from the invention are MIRRA.RTM. and MIRRA MESA.TM.
chemical mechanical polishers also available from Applied
Materials, Inc.
[0029] The exemplary apparatus 100 generally includes a base 108
that supports the ECMP stations 102 and 103, the polishing station
106, a transfer station 110 and a carousel 112. A loading robot 116
generally facilitates transfer of substrates 114 to and from the
transfer station 110 of the apparatus 100 and a factory interface
120. The factory interface 120 may include a cleaning module 122, a
metrology device 104 and one or more substrate storage cassettes
118. One example of a metrology device 104 that may be utilized in
the factory interface 120 is a NovaScan.TM. Integrated Thickness
Monitoring system, available from Nova Measuring Instruments, Inc.,
located in Phoenix, Ariz.
[0030] In one embodiment, the transfer station 110 includes an
input buffer station 124, an output buffer station 126, a transfer
robot 132, and a load cup assembly 128. The input buffer station
124 accepts substrates from the factory interface 120 by the
loading robot 116. The loading robot 116 is also utilized to return
polished substrates from the output buffer station 126 to the
factory interface 120. The transfer robot 132 is utilized to move
substrates between the buffer stations 124, 126 and the load cup
assembly 128.
[0031] In one embodiment, the transfer robot 128 includes two
gripper assemblies, each having pneumatic gripper fingers that hold
the substrate 114 by the substrate's edge. The transfer robot 132
may simultaneously transfer a substrate to be processed from the
input buffer station 124 to the load cup assembly 128 while
transferring a processed substrate from the load cup assembly 128
to the output buffer station 126.
[0032] The carousel 112 has a plurality of arms 138, each
respectively supporting one of a plurality of polishing heads 130.
Each polishing head 130 retains one substrate 114 during
processing. Substrates are loaded and unloaded from the polishing
heads 130 by the load cup assembly 128. One of the arms 138
depicted in FIG. 2 is not shown so that the transfer station 110
may be seen. The carousel 112 moves the polishing heads 130 between
the load cup assembly 128 of the transfer station 110, the ECMP
stations 102 and 103 and the polishing stations 106. One carousel
112 that may be adapted to benefit from the invention is generally
described in U.S. Pat. No. 5,804,507, which is hereby incorporated
by reference in its entirety. It is contemplated that other
transfer mechanisms may be utilized to move substrates between the
stations 102, 103, 104 and the transfer station 110.
[0033] The polishing head 130 retains the substrate 114 against the
ECMP stations 102 and 103 or polishing station 106 during
processing. Examples of embodiments of polishing heads 130 that may
be adapted to benefit from the invention are described in U.S. Pat.
No. 6,183,354. Other polishing heads that may be adapted benefit
from the invention include TITAN HEAD.TM. and TITAN PROFILER.TM.
wafer carriers, available from Applied Materials, Inc. The
arrangement of the ECMP stations 102 and 103 and polishing station
106 on the apparatus 100 allows for the substrate 114 to be
sequentially polished by moving the substrate between stations
while being retained in the same polishing head 130. Alternatively,
substrates may be polished in other sequences.
[0034] To facilitate control of the polishing apparatus 100 and
processes performed thereon, a controller 140 comprising a central
processing unit (CPU) 142, memory 144, and support circuits 146 is
connected to the polishing apparatus 100. The CPU 142 may be one of
any form of computer processor that can be used in an industrial
setting for controlling various drives and pressures. The memory
144 is connected to the CPU 142. The memory 144, or
computer-readable medium, may be one or more of readily available
memories such as random access memory (RAM), read only memory
(ROM), floppy disk, hard disk, or any other form of digital
storage, local or remote. The support circuits 146 are connected to
the CPU 142 for supporting the processor in a conventional manner.
These circuits include cache, power supplies, clock circuits,
input/output circuitry, subsystems, and the like.
[0035] FIG. 3 depicts one embodiment of the ECMP station 102 and/or
ECMP station 103 as a cross-sectional view of one embodiment of a
"face-down" process cell 200. The process cell 200 generally
includes a basin 204 and a polishing head 202. A substrate 208 is
retained in the polishing head 202 and lowered into the basin 204
during processing in a face down (e.g., backside up) orientation.
An electrolyte, such as described herein, flows into the basin 204
and is in contact with the substrate's surface and a polishing
article assembly 222, while the polishing head 202 places the
substrate 208 in contact with the polishing article assembly 222.
The basin 204 includes the polishing article assembly 222, a bottom
244 and sidewalls 246 that define a container that houses the
polishing article assembly 222. The sidewalls 246 include a port
218 formed therethrough to allow removal of polishing composition
from the basin 204. The port 218 is coupled to a valve 220 to
selectively drain or retain the polishing composition in the basin
204.
[0036] The substrate 208 and the polishing article assembly 222
disposed in the basin 204 are moved relative to each other to
provide a polishing motion (or motion that enhances polishing
uniformity). The polishing motion generally comprises at least one
motion defined by an orbital, rotary, linear or curvilinear motion,
or combinations thereof, among other motions. The polishing motion
may be achieved by moving either or both of the polishing head 202
and/or the basin 204. The polishing head 202 may be stationary or
driven to provide at least a portion of the relative motion between
the basin 204 and the substrate 208 held by the polishing head 202.
In the embodiment depicted in FIG. 3, the polishing head 202 is
coupled to a drive system 210. The drive system 210 can generally
move the polishing head 202 with at least a rotary, orbital, sweep
motion, or combinations thereof.
[0037] The polishing head 202 generally retains the substrate 208
during processing. In one embodiment, the polishing head 202
includes a housing 214 enclosing a bladder 216. The bladder 216 may
be deflated when contacting the substrate to create a vacuum
therebetween, thus securing the substrate to the polishing head 202
to allow placement and removal of the substrate. The bladder 216
may additionally be inflated and pressurized to bias and assure
contact between the substrate and the polishing article assembly
222 retained in the basin 204. A retaining ring 238 is coupled to
the housing 214 and circumscribes the substrate 208 to prevent the
substrate from slipping out from the polishing head 202 while
processing. One polishing head that may be adapted to benefit from
the invention is a TITAN HEAD.TM. carrier head available from
Applied Materials, Inc., located in Santa Clara, Calif. Another
example of a polishing head that may be adapted to benefit from the
invention is described in U.S. Pat. No. 6,159,079, issued Dec. 12,
2001, which is hereby incorporated herein by reference in its
entirety.
[0038] The basin 204 is generally fabricated from a plastic such as
fluoropolymers, polytetrafluoroethylene (PTFE) polymers, such as
TEFLON.RTM., perfluoroalkoxy resin (PFA), polyethylene-based
plastics (PE), sulfonated polyphenylether sulfones (PES), or other
materials that are compatible or non-reactive with the polishing
composition or other chemicals used in the processing cell 200. The
basin 204 is rotationally supported above a base 206 by bearings
234. A drive system 236 is coupled to the basin 204 and rotates the
basin 204 during processing. A catch basin 228 is disposed on the
base 206 and circumscribes the basin 204 to collect processing
fluids, such as a polishing composition, that flow out of port 218
disposed through the basin 204 during and/or after processing. An
outlet drain 219 and outlet valve 219A are incorporated in the
invention to allow the polishing composition in the catch basin to
be sent to a reclaim system (not shown) or a waste drain (not
shown).
[0039] In one embodiment the basin 204 is rotated at a velocity
from about 3 rpm (rotations per minute) to about 100 rpm, and the
polishing head 202 is rotated at a velocity from about 5 rpm to
about 200 rpm and also moved linearly at a velocity from about 5
cm/s (centimeters per second) to about 25 cm/s in a direction
radial to the basin 204. The preferred ranges for a 200 mm diameter
substrate are a basin 204 rotational velocity from about 5 rpm to
about 40 rpm and a polishing head 202 rotational velocity from
about 7 rpm to about 100 rpm and a linear (e.g., radial) velocity
of about 10 cm/s. The preferred ranges for a 300 mm diameter
substrate are a basin 204 rotational velocity from about 5 rpm to
about 20 rpm and a polishing head 202 rotational velocity from
about 7 rpm to about 50 rpm and a linear (e.g., radial) velocity of
about 10 cm/s. In one embodiment of the present invention the basin
204 has a diameter between about 17 inches (43.2 cm) and about 30
inches (76.2 cm). The polishing head 202 may move along the radius
of the basin 204 for a distance between about 0.1 inches (2.5 mm)
and about 2 inches (5.1 cm).
[0040] A polishing composition delivery system 232 is generally
disposed adjacent the basin 204. The polishing composition delivery
system 232 includes a nozzle or outlet 230 coupled to a polishing
composition source 242. The outlet 230 delivers polishing
composition or other processing fluids from the polishing
composition source 242 into the basin 204. Alternatively, the
polishing composition delivery system may provide polishing
composition through an inlet (not shown) in the bottom 244 of the
process cell, thus allowing polishing composition to flow through
the polishing article assembly 222 to contact the conductive
polishing article 203 and substrate 208. The polishing composition
source 242 schematically shown here generally includes a source of
all of the chemicals required to supply and support the polishing
composition during processing. It is further contemplated in one
embodiment of the current design to continually recirculate the
polishing composition through the polishing article assembly 222
and across the surface of the substrate 208. In one embodiment the
flow rate of polishing composition flowing through the process cell
200 is from about 0.1 L/min (liters per minute) to about 2
L/min.
[0041] Optionally, and shown in FIG. 3, a conditioning device 250
may be provided proximate the basin 204 to periodically condition
or regenerate the polishing article assembly 222. Typically, the
conditioning device 250 includes an arm 252 coupled to a stanchion
254 that is adapted to position and sweep a conditioning element
258 across polishing article assembly 222. The conditioning element
258 is coupled to the arm 252 by a shaft 256 to allow clearance
between the arm 252 and sidewalls 246 of the basin 204 while the
conditioning element 258 is in contact the polishing article
assembly 222. The conditioning element 258 is typically a diamond
or silicon carbide disk, which may be patterned to enhance working
the surface of the polishing article assembly 222 into a
predetermined surface condition/state that enhances process
uniformity. Alternatively, the conditioning element 258 can be made
of a NYLON.TM. brush or similar conditioner for in-situ
conditioning the conductive polishing article 203. One conditioning
element 258 that may be adapted to benefit from the invention is
described in U.S. patent application Ser. No. 09/676,280, filed
Sep. 28, 2000 by Li et al., which is incorporated herein by
reference to the extent not inconsistent with the claims aspects
and description herein.
[0042] A power source 224 is coupled to the polishing article
assembly 222 by electrical leads 223A, 223B. The power source 224
applies an electrical bias to the polishing article assembly 222 to
drive an electrochemical process described below. The leads 223A,
223B are routed through a slip ring 226 disposed below the basin
204. The slip ring 226 facilitates continuous electrical connection
between the power source 224 and electrodes (209 and 203) in the
polishing article assembly 222 as the basin 204 rotates. The leads
223A, 223B may be wires, tapes or other conductors compatible with
process fluids or having a covering or coating that protects the
leads from the process fluids. Examples of materials that may be
utilized in the leads 223A, 223B include copper, graphite,
titanium, platinum, gold, and HASTELOY.RTM. among other materials
which can have an insulating coating on its exterior surface.
Coatings disposed around the leads may include polymers such as
fluorocarbons, PVC, polyamide and the like. The slip ring 226 can
be purchased from manufacturers such as IDM Electronics LTD,
Reading Berkshire, England, a division of Kaydon Corporation, Ann
Arbor, Mich.
[0043] The polishing article assembly 222 generally includes a
conductive polishing article 203 coupled to a backing 207 and an
electrode 209. The backing 207 may also be coupled to an electrode
209. The conductive polishing article 203 and the backing 207 have
a plurality of holes or pores formed therein to allow the polish
composition to make contact with, and thus provide a conductive
path between the substrate 208 and the electrode 209. A dielectric
insert (not shown) may be disposed between the conductive polishing
article 203 and the backing 207 or between the backing 207 and the
electrode 209 to regulate the electrolyte flow through all or a
portion of the conductive polishing article 203, by use of a
plurality of holes or pores formed therein. The conductive
polishing article 203 is used to apply a uniform bias to the
substrate surface by use of a conductive surface that makes contact
with the surface of the substrate. The use of a conductive
polishing article is generally preferred over the use of a
conventional substrate contacting means such as discrete or point
contacts, but should not be considered limiting to the scope of the
present invention. During the anodic dissolution process the
electrode 209 is generally biased as a cathode and the conductive
polishing article 203 and substrate are biased as an anode through
use of the power supply 224.
[0044] Examples of the conductive polishing article 203 are more
fully disclosed in U.S. patent Publication No. 20020119286, filed
on Dec. 27, 2001, and U.S. patent application Ser. No. 10/211,626,
filed on Aug. 2, 2002, which are incorporated by reference herein
to the extent not inconsistent with the claimed aspects and
disclosure herein. Examples of an embodiment of the conductive
polishing article 203 utilizing conventional polishing material
(non-conductive) with discrete conductive contacts are more fully
disclosed in the U.S. patent application Ser. No. 10/211,626, filed
on Aug. 2, 2003, which is incorporated by reference herein to the
extent not inconsistent with the claimed aspects and disclosure
herein.
[0045] As the polishing article assembly 222 includes elements
comprising both an anode and cathode of an electrochemical cell,
both the anode and a cathode may be replaced simultaneously by
simply removing a used polishing article assembly 222 from the
basin 204 and inserting a new polishing article assembly 222 with
fresh electrical and supporting components into the basin 204. The
face-down polishing apparatus is more fully disclosed in U.S.
patent Publication No. 20030213703, filed May 16, 2002, commonly
assigned to Applied Materials Inc., of which paragraphs 27-82 are
incorporated herein by reference to the extent not inconsistent
with the claims aspects and description herein.
[0046] Typically, the conductive polishing article 203, the backing
207, optionally, the dielectric insert, and the electrode 209 are
secured together to form a unitary body that facilitates removal
and replacement of the polishing article assembly 222 from the
basin 204. The conductive polishing article 203, the backing 207,
optionally the dielectric insert, and/or the electrode 209 may be
coupled by use of methods such as adhesive bonding, thermal
bonding, sewing, binding, heat staking, riveting, by use of
fasteners and clamping, among others.
[0047] The process cell 200 may be disposed on a polishing platform
with one or more chemical mechanical polishing platens suitable for
conductive material and/or barrier material removal. Such chemical
mechanical polishing platens may contain fixed-abrasive or
non-abrasive polishing articles and may use abrasive containing or
abrasive-free polishing composition. Additionally the polishing
articles for the polishing platens may be hard polishing articles,
having a durometer or hardness of 50 or greater on a shore D Scale
or soft polishing articles having a durometer or hardness of less
than 50, typically 40 or less, on a shore D Scale.
[0048] For example, the polishing platform may be of a three platen
variety, such as the MIRRA.RTM. polishing system, the MIRRA
MESA.TM. polishing system, and the REFLEXION.RTM. polishing system,
that are commercially available from Applied Materials, Inc., of
Santa Clara, Calif., with the process cell 200 disposed at a first
platen position, a conventional chemical mechanical polishing
platen with a hard or soft polishing pad on a second platen
position, and a barrier removal platen on the third platen
position. In another example, a first process cell 200 disposed at
a first platen position, for example, ECMP station 102, for a first
electrochemical mechanical polishing process, a second process cell
200 disposed at a second platen position, for example, ECMP station
103, for a second electrochemical mechanical polishing process, and
a conventional chemical mechanical polishing platen with a hard or
soft polishing pad, such as polishing station 106, on a third
platen position. However, any system enabling electrochemical
mechanical polishing with or without the presence of chemical
mechanical polishing ability may be used to advantage.
[0049] Polishing Processes
[0050] Methods are provided for polishing a substrate to remove
residues and minimize dishing within features, while increasing
throughput with a decrease in polishing time. The methods may be
performed by an electrochemical polishing technique. In one aspect,
the method may include processing a substrate having a conductive
material layer disposed over features, supplying a first polishing
composition to the surface of the substrate, applying a pressure
between the substrate and a polishing article, providing relative
motion between the substrate and the polishing article, applying a
bias between a first electrode and a second electrode in electrical
contact with the substrate, removing at least about 50% of the
conductive material, supplying a second polishing composition,
applying a second bias, and continuing to remove the conductive
material.
[0051] One embodiment of the process will now be described in
reference to FIGS. 4A-4D, which are schematic cross-sectional views
of a substrate being processed according to methods and
compositions described herein. Referring to FIG. 4A, a substrate
generally includes a dielectric layer 310 formed on a substrate
300. A plurality of apertures, such as vias, trenches, contacts, or
holes, are patterned and etched into the dielectric layer 310, such
as a dense array of narrow feature definitions 320 and low density
of wide feature definitions 330. The apertures may be formed in the
dielectric layer 310 by conventional photolithographic and etching
techniques.
[0052] FIG. 4A depicts a substrate 300 and a conductive layer 370
before ECMP processes have been applied. FIG. 4B illustrates the
substrate after at least about 50% of the conductive layer 370 has
been removed by applying a first ECMP process. The remaining
conductive layer 370 disposed upon a barrier layer 340 is removed
by applying a second ECMP process, as illustrated in FIG. 4C.
Furthermore, as illustrated in FIG. 4D, the remaining barrier layer
340 on the dielectric layer 310 may be removed by a third process,
such as a CMP process or a third ECMP process.
[0053] The terms narrow and wide feature definitions may vary
depending on the structures formed on the substrate surface, but
can generally be characterized by the respective deposition
profiles of excessive material deposition (or high overburden)
formed over narrow feature definitions and minimal or low material
deposition (minimal or low overburden), over wide feature
definitions. For example narrow feature definitions may be about
0.13 .mu.m in size and may have a high overburden as compared to
wide feature definitions that may be about 10 .mu.m in size and
that may have minimal or insufficient overburden. However, high
overburdens and low overburdens do not necessarily have to form
over features, but may form over areas on the substrate surface
between features.
[0054] The dielectric layer 310 may comprise one or more dielectric
materials conventionally employed in the manufacture of
semiconductor devices. For example, dielectric materials may
include materials such as silicon dioxide, phosphorus-doped silicon
glass (PSG), boron-phosphorus-doped silicon glass (BPSG), and
silicon dioxide derived from tetraethyl orthosilicate (TEOS) or
silane by plasma enhanced chemical vapor deposition (PECVD). The
dielectric layer may also comprise low dielectric constant
materials, including fluoro-silicon glass (FSG), polymers, such as
polyamides, carbon-containing silicon oxides, such as BLACK
DIAMOND.TM. dielectric material, silicon carbide materials, which
may be doped with nitrogen and/or oxygen, including BLOK.TM.
dielectric materials, available from Applied Materials, Inc. of
Santa Clara, Calif.
[0055] A barrier layer 340 is disposed conformally in the feature
definitions 320 and 330 and on the substrate 300. The barrier layer
340 may comprise metals or metal nitrides, such as tantalum,
tantalum nitride, tantalum silicon nitride, titanium, titanium
nitride, titanium silicon nitride, tungsten, tungsten nitride and
combinations thereof, or any other material that may limit
diffusion of materials between the substrate and/or dielectric
materials and any subsequently deposited conductive materials.
[0056] A conductive material layer 360 is disposed on the barrier
layer 340. The term "conductive material layer" as used herein is
defined as any conductive material, such as copper, tungsten,
aluminum, and/or their alloys used to fill a feature to form lines,
contacts or vias. While not shown, a seed layer of a conductive
material may be deposited on the barrier layer prior to the
deposition of the conductive material layer 360 to improve
interlayer adhesion and improve subsequent deposition processes.
The seed layer may be of the same material as the subsequent
material to be deposited.
[0057] One type of conductive material layer 360 comprises copper
containing materials. Copper containing materials include copper,
copper alloys (e.g., copper-based alloys containing at least about
80 weight percent copper) or doped copper. As used throughout this
disclosure, the phrase "copper containing material," the word
"copper," and the symbol "Cu" are intended to encompass copper,
copper alloys, doped copper, and combinations thereof.
Additionally, the conductive material may comprise any conductive
material used in semiconductor manufacturing processing.
[0058] In one embodiment, the deposited conductive material layer
360 has a deposition profile of excessive material deposition or
high overburden 370 formed over narrow feature definitions 320 and
minimal overburden 380 over wide feature definitions 330. In
another embodiment, high overburdens and minimal overburdens are
arbitrarily formed across the substrate surface between
features.
[0059] The substrate may then be positioned in a polishing
apparatus, such as the apparatus described herein and shown in FIG.
3 and exposed to a polishing composition that can form a
passivation layer 390 on the conductive material layer.
[0060] Polishing Compositions
[0061] Suitable polishing compositions that may be used with the
processes described herein to planarize metals, such as copper, may
comprise an acid based electrolyte system, one or more chelating
agents, one or more corrosion inhibitors, one or more inorganic or
organic acid salts, one or more pH adjusting agents to produce a pH
between about 2 and about 10, at least one oxidizer, and abrasive
particulates.
[0062] Although the polishing compositions are particularly useful
for removing copper, it is believed that the polishing compositions
also may be used for the removal of other conductive materials,
such as aluminum, platinum, tungsten, titanium, titanium nitride,
tantalum, tantalum nitride, cobalt, gold, silver, ruthenium and
combinations thereof. Mechanical abrasion, such as from contact
with the conductive polishing article 203 may be used with the
polishing composition to improve planarity and improve removal rate
of these conductive materials.
[0063] The polishing composition includes an acid based electrolyte
system for providing electrical conductivity. Suitable acid based
electrolyte systems include, for example, phosphoric acid based
electrolytes, sulfuric acid, nitric acid, perchloric acid, acetic
acid, citric acid, salts thereof and combinations thereof. Suitable
acid based electrolyte systems include an acid electrolyte, such as
phosphoric acid, boric acid and/or citric acid, as well as acid
electrolyte derivatives, including ammonium, potassium, sodium,
calcium and copper salts thereof. The acid based electrolyte system
may also buffer the composition to maintain a desired pH level for
processing a substrate.
[0064] Examples of suitable acid based electrolytes include
compounds having a phosphate group (PO.sub.4.sup.3-), such as,
phosphoric acid, copper phosphate, potassium phosphates
(K.sub.XH.sub.(3-X)PO.sub.4) (x=1, 2 or 3), such as potassium
dihydrogen phosphate (KH.sub.2PO.sub.4), dipotassium hydrogen
phosphate (K.sub.2HPO.sub.4), ammonium phosphates
((NH.sub.4).sub.XH.sub.(3-X)PO.sub.4) (x=1, 2 or 3), such as
ammonium dihydrogen phosphate ((NH.sub.4)H.sub.2PO.sub.4),
diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4),
compounds having a nitrite group (NO.sub.3.sup.1-), such as, nitric
acid or copper nitrate, compounds having a boric group
(BO.sub.3.sup.3-), such as, orthoboric acid (H.sub.3BO.sub.3) and
compounds having a sulfate group (SO.sub.4.sup.2-), such as
sulfuric acid (H.sub.2SO.sub.4), ammonium hydrogen sulfate
((NH.sub.4)HSO.sub.4), ammonium sulfate, potassium sulfate, copper
sulfate, derivatives thereof and combinations thereof. The
invention also contemplates that conventional electrolytes known
and unknown may also be used in forming the composition described
herein using the processes described herein.
[0065] The acid based electrolyte system may contains an acidic
component that can take up about 1 to about 30 percent by weight
(wt %) or volume (vol %) of the total composition of solution to
provide suitable conductivity for practicing the processes
described herein. Examples of acidic components include dihydrogen
phosphate and/or diammonium hydrogen phosphate and may be present
in the polishing composition in amounts from about 15 wt % to about
25 wt %. Alternately, phosphoric acid may be present in
concentrations up to 30 wt %, for example, between about 2 wt % and
about 6 wt %.
[0066] One aspect or component of the present invention is the use
of one or more chelating agents to complex with the surface of the
substrate to enhance the electrochemical dissolution process. In
any of the embodiments described herein, the chelating agents can
bind to a conductive material, such as copper ions, increase the
removal rate of metal materials and/or improve dissolution
uniformity across the substrate surface. The metal materials for
removal, such as copper, may be in any oxidation state, such as 0,
1, or 2, before, during or after ligating with a functional group.
The functional groups can bind the metal materials created on the
substrate surface during processing and remove the metal materials
from the substrate surface. The chelating agents may also be used
to buffer the polishing composition to maintain a desired pH level
for processing a substrate. The chelating agents may also form or
enhance the formation of a passivation layer on the substrate
surface.
[0067] The one or more chelating agents can include compounds
having one or more functional groups selected from the group of
amine groups, amide groups, carboxylate groups, dicarboxylate
groups, tricarboxylate groups, hydroxyl groups, a mixture of
hydroxyl and carboxylate groups, and combinations thereof. The one
or more chelating agents may also include salts of the chelating
agents described herein. The polishing composition may include one
or more chelating agents at a concentration between about 0.1% and
about 15% by volume or weight, but preferably utilized between
about 0.1% and about 4% by volume or weight. For example, about 2%
by volume of ethylenediamine may be used as a chelating agent.
[0068] Examples of suitable chelating agents having one or more
carboxylate groups include citric acid, tartaric acid, succinic
acid, oxalic acid, amino acids, salts thereof, and combinations
thereof. For example, chelating agents may include ammonium
citrate, potassium citrate, ammonium succinate, potassium
succinate, ammonium oxalate, potassium oxalate, potassium tartrate,
and combinations thereof. The salts may have multi-basic states,
for example, citrates have mono-, di- and tri-basic states. Other
suitable acids having one or more carboxylate groups include acetic
acid, adipic acid, butyric acid, capric acid, caproic acid,
caprylic acid, glutaric acid, glycolic acid, formaic acid, fumaric
acid, lactic acid, lauric acid, malic acid, maleic acid, malonic
acid, myristic acid, plamitic acid, phthalic acid, propionic acid,
pyruvic acid, stearic acid, valeric acid, derivatives thereof,
salts thereof and combinations thereof. Further examples of
suitable chelating agents include compounds having one or more
amine and amide functional groups, such as ethylenediamine (EDA),
diethylenetriamine, diethylenetriamine derivatives, hexadiamine,
amino acids, glycine, ethylenediaminetetraacetic acid (EDTA),
methylformamide, derivatives thereof, salts thereof and
combinations thereof. For example, EDTA includes the acid as well
as a variety of salts, such as sodium, potassium and calcium (e.g.,
Na.sub.2EDTA, Na.sub.4EDTA, K.sub.4EDTA or Ca.sub.2EDTA).
[0069] In any of the embodiments described herein, the inorganic or
organic acid salts may be used to perform as a chelating agent. The
polishing composition may include one or more inorganic or organic
salts at a concentration between about 0.1% and about 15% by volume
or weight of the composition, for example, between about 0.1% and
about 8% by volume or weight. For example, about 2% by weight of
ammonium citrate may be used in the polishing composition.
[0070] Examples of suitable inorganic or organic acid salts include
ammonium and potassium salts or organic acids, such as ammonium
oxalate, ammonium citrate, ammonium succinate, monobasic potassium
citrate, dibasic potassium citrate, tribasic potassium citrate,
potassium tartarate, ammonium tartarate, potassium succinate,
potassium oxalate, and combinations thereof. Additionally, ammonium
and potassium salts of the carboxylate acids may also be used.
[0071] In any of the embodiments described herein, the corrosion
inhibitors can be added to reduce the oxidation or corrosion of
metal surfaces by forming a passivation layer that minimizes the
chemical interaction between the substrate surface and the
surrounding electrolyte. The layer of material formed by the
corrosion inhibitors thus tends to suppress or minimize the
electrochemical current from the substrate surface to limit
electrochemical deposition and/or dissolution. The polishing
composition may include between about 0.001% and about 5.0% by
weight of the organic compound from one or more azole groups. The
commonly preferred range being between about 0.2% and about 0.4% by
weight.
[0072] Examples of organic compounds having azole groups include
benzotriazole (BTA), mercaptobenzotriazole,
5-methyl-1-benzotriazole (TTA), and combinations thereof. Other
suitable corrosion inhibitors include film forming agents that are
cyclic compounds, for example, imidazole, benzimidazole, triazole,
and combinations thereof. Derivatives of benzotriazole, imidazole,
benzimidazole, triazole, with hydroxy, amino, imino, carboxy,
mercapto, nitro and alkyl substituted groups may also be used as
corrosion inhibitors. Other corrosion inhibitor includes urea and
thiourea among others.
[0073] Alternatively, polymeric inhibitors, for non-limiting
examples, polyalkylaryl ether phosphate or ammonium nonylphenol
ethoxylate sulfate, may be used in replacement or conjunction with
azole containing corrosion inhibitors in an amount between about
0.002% and about 1.0% by volume or weight of the composition.
[0074] One or more pH adjusting agents is preferably added to the
polishing composition to achieve a pH between about 2 and about 10,
and preferably between a pH of about 3 and about 7. The amount of
pH adjusting agent can vary as the concentration of the other
components is varied in different formulations, but in general the
total solution may include up to about 70 wt % of the one or more
pH adjusting agents, but preferably between about 0.2% and about
25% by volume. Different compounds may provide different pH levels
for a given concentration, for example, the composition may include
between about 0.1% and about 10% by volume of a base, such as
potassium hydroxide, ammonium hydroxide, sodium hydroxide or
combinations thereof, providing the desired pH level.
[0075] The one or more pH adjusting agents can be chosen from a
class of organic acids, for example, carboxylic acids, such as
acetic acid, citric acid, oxalic acid, phosphate-containing
components including phosphoric acid, ammonium phosphates,
potassium phosphates, and combinations thereof, or a combination
thereof. Inorganic acids including phosphoric acid, sulfuric acid,
hydrochloric, nitric acid, derivatives thereof and combinations
thereof, may also be used as a pH adjusting agent in the polishing
composition.
[0076] The balance or remainder of the polishing compositions
described herein is a solvent, such as a polar solvent, including
water, preferably deionized water. Other solvent may be used solely
or in combination with water, such as organic solvents. Organic
solvents include alcohols, such as isopropyl alcohol or glycols,
ethers, such as diethyl ether, furans, such as tetrahydrofuran,
hydrocarbons, such as pentane or heptane, aromatic hydrocarbons,
such as benzene or toluene, halogenated solvents, such as methylene
chloride or carbon tetrachloride, derivatives, thereof and
combinations thereof.
[0077] The polishing composition may include one or more surface
finish enhancing and/or removal rate enhancing materials including
abrasive particles, one or more oxidizers, and combinations
thereof.
[0078] Abrasive particles may be used to improve the surface finish
and removal rate of conductive materials from the substrate surface
during polishing. The addition of abrasive particles to the
polishing composition can allow the final polished surface to
achieve a surface roughness of that comparable with a conventional
CMP process even at low pad pressures. Surface finish, or surface
roughness, has been shown to have an effect on device yield and
post polishing surface defects. Abrasive particles may comprise up
to about 30 wt % of the polishing composition during processing. A
concentration between about 0.001 wt % and about 5 wt % of abrasive
particles may be used in the polishing composition.
[0079] Suitable abrasives particles include inorganic abrasives,
polymeric abrasives, and combinations thereof. Inorganic abrasive
particles that may be used in the electrolyte include, but are not
limited to, silica, alumina, zirconium oxide, titanium oxide,
cerium oxide, germania, or any other abrasives of metal oxides,
known or unknown. For example, colloidal silica may be positively
activated, such as with an alumina modification or a silica/alumina
composite. The typical abrasive particle size used in one
embodiment of the current invention is generally from about 1 nm to
about 1,000 nm, preferably from about 10 nm to about 100 nm.
Generally, suitable inorganic abrasives have a Mohs hardness of
greater than 6, although the invention contemplates the use of
abrasives having a lower Mohs hardness value.
[0080] The polymer abrasives described herein may also be referred
to as "organic polymer particle abrasives", "organic abrasives" or
"organic particles." The polymeric abrasives may comprise abrasive
polymeric materials. Examples of polymeric abrasives materials
include polymethylmethacrylate, polymethyl acrylate, polystyrene,
polymethacrylonitrile, and combinations thereof.
[0081] The polymeric abrasives may have a Hardness Shore D of
between about 60 and about 80, but can be modified to have greater
or lesser hardness value. The softer polymeric abrasive particles
can help reduce friction between a polishing article and substrate
and may result in a reduction in the number and the severity of
scratches and other surface defects as compared to inorganic
particles. A harder polymeric abrasive particle may provide
improved polishing performance, removal rate and surface finish as
compared to softer materials.
[0082] The hardness of the polymer abrasives can be varied by
controlling the extent of polymeric cross-linking in the abrasives,
for example, a higher degree of cross-linking produces a greater
hardness of polymer and, thus, abrasive. The polymeric abrasives
are typically formed as spherical shaped beads having an average
diameter between about 0.1 micron to about 20 microns or less.
[0083] The polymeric abrasives may be modified to have functional
groups, e.g., one or more functional groups, that have an affinity
for, i.e., can bind to, the conductive material or conductive
material ions at the surface of the substrate, thereby facilitating
the ECMP removal of material from the surface of a substrate. For
example, if copper is to be removed in the polishing process, the
organic polymer particles can be modified to have an amine group, a
carboxylate group, a pyridine group, a hydroxide group, ligands
with a high affinity for copper, or combinations thereof, to bind
the removed copper as substitutes for or in addition to the
chemically active agents in the polishing composition, such as the
chelating agents or corrosion inhibitors. The substrate surface
material, such as copper, may be in any oxidation state, such as 0,
1+, or 2+, before, during or after ligating with a functional
group. The functional groups can bind to the metal material(s) on
the substrate surface to help improve the uniformity and surface
finish of the substrate surface.
[0084] Additionally, the polymeric abrasives have desirable
chemical properties, for example, the polymer abrasives are stable
over a broad pH range and are not prone to aggregating to each
other, which allow the polymeric abrasives to be used with reduced
or no surfactant or no dispersing agent in the composition.
[0085] Alternatively, inorganic particles coated with the polymeric
materials described herein may also be used with the polishing
composition. It is within the scope of the current invention for
the polishing composition to contain polymeric abrasives, inorganic
abrasives, the polymeric coated inorganic abrasives, and any
combination thereof depending on the desired polishing performance
and results.
[0086] One or more oxidizers may be used herein to enhance the
removal or removal rate of the conductive material from the
substrate surface. An oxidizing agent is generally an agent that
reacts with a material by accepting an electron(s). In the current
embodiment the oxidizer is used to react with the surface of the
substrate that is to be polished, which then aids in the removal of
the desired material. For example, an oxidizer may be used to
oxidize a metal layer to a corresponding oxide or hydroxide, for
example, copper to copper oxide. Existing copper that has been
oxidized, including Cu.sup.1+ ions, may further be oxidized to a
higher oxidation state, such as Cu.sup.2+ ions, which may then
promote the reaction with one or more of the chelating agents.
Also, in some instances the oxidizing agent can be used in some
chemistries (e.g., low pH) that can enhance the chemical etching of
the surface of the substrate to further increase the removal rate
from the anode surface. In cases where no bias is applied to the
surface of the substrate the inhibitors and chelating agents will
complex with the metal ions on the surface that become dislodged
from the surface due to the relative motion and pressure applied by
the conductive pad 203. The addition of abrasives can further
improve the removal rate of the complexed metal ions due to the
abrasive particles ability to increase that contact area between
the conductive pad 203 and the substrate surface.
[0087] In the case of ECMP, the conductive layer on the substrate
surface is biased anodically above a threshold potential, by use of
the power source 224 and the electrode 209, thus causing the metal
on the substrate surface to "oxidize" (i.e., a metal atom gives up
one or more electrons to the power source 224). The ionized or
"oxidized" metal atoms thus dissolve into the electrolyte solution
with the help of components in the electrolyte. In the case where
copper is the desired material to be removed, it can be oxidized to
a Cu.sup.1+ or a Cu.sup.2+ oxidation state. Due to the presence of
the inhibitors and/or chelating agents found in the polishing
composition, the electrochemical dissolution process of the metal
ions into the electrolyte is more limited than a polishing
composition which does not contain these components. The presence
of the inhibitors and/or chelating agents also appears to have an
effect on the attachment strength of the metal ion(s) and inhibitor
and/or chelating agent complex to the surface of the substrate. It
has been found that in one embodiment that the removal rate in an
ECMP process can be increased by the addition of an oxidizing
agent. It is thought that the oxidizing agent tends to further
oxidize the metal ions formed due to the anodic bias, which in the
case of copper brings it to the more stable Cu.sup.2+ oxidation
state. The inhibitors and/or chelating agents found in the
polishing composition complex with the oxidized metal ions which
tend to have a lower attachment, or bond, strength due to the way
the inhibitor bonds to the oxidized metal ion and metal surface.
The lower attachment strength allows the complexed metal ion to be
more easily and efficiently removed due to the interaction of the
substrate surface and the conductive pad 203. The addition of
abrasives to the ECMP polishing composition can further improve the
removal rate of the complexed metal ions due to the abrasive
particles' ability to increase contact area between the conductive
pad 203 and the substrate surface.
[0088] The polishing composition may include one or more additive
compounds. Additive compounds include electrolyte additives
including, but not limited to, suppressors, enhancers, levelers,
brighteners, stabilizers, and stripping agents to improve the
effectiveness of the polishing composition in polishing of the
substrate surface. For example, certain additives may decrease the
ionization rate of the metal atoms, thereby inhibiting the
dissolution process, whereas other additives may provide a
finished, shiny substrate surface. The additives may be present in
the polishing composition in concentrations up to about 15% by
weight or volume, and may vary based upon the desired result after
polishing.
[0089] Further, controlling the amounts and types of constituents
of the polishing composition, such as corrosion inhibitors and
oxidizers, can result in tuning the desired removal rate of the
process. For example reduced amounts of corrosion inhibitor will
result in an increase in the material removal rate as compared to
compositions having higher corrosion inhibitor concentrations. In
cases where the polishing composition does not contain corrosion
inhibitors the ECMP material removal rate is greatly increased over
a polishing composition which contains a corrosion inhibitor due to
the formation of the metal ions and inhibitor complex which tends
to shield the surface of the substrate to the electrolyte. Likewise
reduced amounts of oxidizers will generally result in lower removal
rates compared to compositions having higher oxidizer compositions.
It has been suggested that at low concentrations of the oxidizer,
the corrosion inhibitor and/or chelating agent can complex with a
metal ion before it becomes oxidized further by the oxidizing agent
due to kinetic effects limiting the supply of the oxidizer to the
surface of the substrate. The corrosion inhibitor and metal ion
complex can thus affect the removal efficiency due to the formation
of the stronger attachment strength complexed metal ions. An
example of a polishing composition described herein includes about
2% by volume ethylenediamine, about 2% by weight ammonium citrate,
about 0.3% by weight benzotriazole, between about 0.1% and about 3%
by volume or weight, for example, about 0.45% hydrogen, peroxide,
and/or about between about 0.01% and 1% by weight, for example
0.15% by weight, of abrasive particles, and about 6% by volume
phosphoric acid. The pH of the composition is about 5, which may be
achieved by, for example, the composition further including
potassium hydroxide to adjust the pH to the preferred range. The
remainder of the polishing composition is deionized water.
[0090] The oxidizer can be present in the polishing composition in
an amount ranging between about 0.01% and about 90% by volume or
weight, for example, between about 0.1% and about 20% by volume or
weight. In an embodiment of the polishing composition, between
about 0.1% to about 15% by volume or weight of hydrogen peroxide is
present in the polishing composition. In one embodiment, the
oxidizer is added to the rest of the polishing composition just
prior to beginning the ECMP process. Examples of suitable oxidizers
include peroxy compounds, e.g., compounds that may disassociate
through hydroxy radicals, such as hydrogen peroxide and its adducts
including urea hydrogen peroxide, percarbonates, and organic
peroxides including, for example, alkyl peroxides, cyclical or aryl
peroxides, benzoyl peroxide, peracetic acid, and ditertbutyl
peroxide. Sulfates and sulfate derivatives, such as monopersulfates
and dipersulfates may also be used including for example, ammonium
peroxydisulfate, potassium peroxydisulfate, ammonium persulfate,
and potassium persulfate. Salts of peroxy compounds, such as sodium
percarbonate and sodium peroxide may also be used.
[0091] The oxidizing agent can also be an inorganic compound or a
compound containing an element in its highest oxidation state.
Examples of inorganic compounds and compounds containing an element
in its highest oxidation state include but are not limited to
periodic acid, periodate salts, perbromic acid, perbromate salts,
perchloric acid, perchloric salts, perbonic acid, nitrate salts
(such as cerium nitrate, iron nitrate, ammonium nitrate), ferrates,
perborate salts and permanganates. Other oxidizing agents include
bromates, chlorates, chromates, iodates, iodic acid, and cerium
(IV) compounds such as ammonium cerium nitrate.
[0092] Surfactants may be one such additive compound in the
polishing composition. One or more surfactants may be used in the
polishing composition to increase the dissolution or solubility of
materials, such as metals and metal ions or by-products produced
during processing, improve chemical stability, and reduce
decomposition of components of the polishing composition. The one
or more surfactants can comprise a concentration between about
0.001% and about 10% by volume or weight of the polishing
composition. A concentration between about 0.01% and about 2% by
volume or weight, for example between about 0.1% and about 1% by
volume or weight, of the surfactants may be used in one embodiment
of the polishing composition. The one or more surfactants may
include non-ionic surfactants as well as ionic surfactants
including anionic surfactants, cationic surfactants, amphoteric
surfactants, and ionic surfactants having more than one ionic
functional group, such as Zweitter-ionic surfactants. Dispersers or
dispersing agents are considered to be surfactants as surfactants
are used herein.
[0093] Other examples of additives include one or more leveling
agents, which are broadly defined herein as additives that suppress
dissolution current on the surface of a substrate. Leveling agents
suppress dissolution current by attaching to conductive materials,
by inhibiting the electrochemical reactions between the electrolyte
and conductive material, and/or form depolarizing agents that limit
electrochemical reactions. A concentration of leveling agents
between about 0.005% and about 10% by volume or weight, for
example, between about 0.05% and about 2% by volume or weight of
the electrolyte solution can be used.
[0094] Leveling agents include, but are not limited to,
polyethylene glycol (PEG) and polyethylene glycol derivatives.
Other leveling agents which can be employed in the process
described herein include any employed in the electroplating or
electropolishing art, such as polyamines, polyamides and polyimides
including polyethyleneimine, polyglycine,
2-amino-1-naphthalenesulfonic acid, 3-amino-1-propanesulfoni- c
acid, 4-aminotoluene-2-sulfonic acid. Leveling agents may be added
to the composition in a range from about 0.05% to about 5% by
volume or weight of the composition. For example, PEG may be added
to a polishing solution with a concentration about 0.2wt %.
[0095] Suppressors, such as electrically resistive additives that
reduce the conductivity of the polishing composition may be added
to the composition in a range from about 0.005% to about 2% by
volume or weight of the composition. Suppressors include
polyacrylamide, polyacrylic acid polymers, polycarboxylate
copolymers, coconut diethanolamide, oleic diethanolamide,
ethanolamide derivatives, or combinations thereof.
[0096] One or more stabilizers may be present in an amount that is
sufficient to produce measurable improvements in composition
stability. The one or more stabilizers may be present in an amount
ranging from about 100 ppm to about 5.0 weight percent (wt %).
Non-limiting examples of preferred stabilizers include but are not
limited to phosphoric acids and phosphoric acid derivatives
including aminotri(methylenephosphonic) acid,
1-hydroxyethylidene-4-diphophonic acid,
hexamethylenediaminetetrame- thylene phosphoric acid, and
diethylenetetramine pentamethylenephosphonic acid, and derivative
salts thereof.
[0097] Accelerators are another example of an additive that may be
included in the polishing composition. Accelerators increase
electrochemical reactions of metals disposed on the substrate
surface to increase metal removal. The composition may include one
or more accelerators at a concentration between about 0.001% and
about 1% by volume or weight, for example, between about 0.25% and
about 0.8% by volume or weight. Accelerators may include
sulfur-containing compounds, such as sulfite or di-sulfate.
[0098] Further examples of additives to the polishing composition
are more fully described in U.S. patent application Ser. No.
10/141,459, filed on May 7, 2002, which is incorporated by
reference herein to the extent not inconsistent with the claimed
aspects and disclosure herein.
[0099] ECMP solutions of varying compositions may be used to remove
bulk material and residual material, such as copper and/or copper
alloys, as well as to remove barrier materials, such as tantalum
nitrides or titanium nitrides. Specific formulations of the
polishing compositions are used to remove the particular materials.
Polishing compositions utilized during embodiments herein are
advantageous for ECMP processes. Generally, ECMP solutions are much
more conductive than traditional CMP solutions. The ECMP solutions
have a conductivity of about 10 mS or higher, while traditional CMP
solutions have a conductivity from about 3 mS to about 5 mS. The
conductivity of the ECMP solutions greatly influences that rate at
which the ECMP process advances, i.e., more conductive solutions
have a faster material removal rate. For removing bulk material,
the ECMP solution has a conductivity of about 10 mS or higher,
preferably in a range from about 30 mS to about 60 mS. For residual
material, the ECMP solution has a conductivity of about 10 mS or
higher, preferably in a range from about 15 mS to about 40 mS.
[0100] A first polishing composition or first ECPM solution used to
remove bulk material may include phosphoric acid, at least one
chelating agent, a corrosion inhibitor, a salt, an oxidizer, or
abrasive particulates. For example, a first polishing solution may
include from about 1 wt % to about 10 wt % of phosphoric acid; from
about 0.1 wt % to about 6 wt % of the at least one chelating agent;
from about 0.01 wt % to about 1 wt % of a corrosion inhibitor; from
about 0.5 wt % to about 10 wt % of a salt, such as ammonium citrate
or copper citrate; from about 0.2 wt % to about 5 wt % of an
oxidizer; and from about 0.05 wt % to about 1 wt % of abrasive
particulates. Also, a first polishing composition may have a pH
adjusting agent in a concentration to maintain a pH from about 4 to
about 7. Generally, a solvent is added to the solution, such as
de-ionized water.
[0101] The first polishing composition includes at least one
chelating agent, such as EDA, EDTA, citric acid, ammonium citrate,
salts thereof, derivatives thereof and combinations thereof. The
corrosion inhibitor of the first polishing composition may include
BTA, TTA, salts thereof, derivatives thereof and combinations
thereof. Salts may be added to the first polishing composition or
may be formed in situ, such as by an acid/base type reaction. Salts
may be inorganic, organic or combinations thereof and include
cations such as ammonium, potassium, sodium, calcium and anions
such as citrate, oxalate, succinate and tartrate. A pH adjusting
agent includes potassium hydroxide, ammonium hydroxide or
combinations thereof. An oxidizer, such as hydrogen peroxide and/or
abrasive particulates, such as colloidal silica activated with
alumina may be added to the first polishing composition.
[0102] A second polishing composition or second ECPM solution used
to residual material may include phosphoric acid, at least one
chelating agent, a corrosion inhibitor, a salt, an oxidizer,
abrasive particulates. For example, a second polishing solution may
include from about 0.1 wt % to about 5 wt % of phosphoric acid;
from about 0.1 wt % to about 5 wt % of the at least one chelating
agent; from about 0.01 wt % to about 1 wt % of a corrosion
inhibitor; from about 0.1 wt % to about 5 wt % of a salt; from
about 0.01 wt % to about 3 wt % of an oxidizer; and from about 0.05
wt % to about 5 wt % of abrasive particulates. Also, a second
polishing composition may have a pH adjusting agent in a
concentration to maintain a pH from about 4 to about 7. Generally,
a solvent is added to the solution, such as de-ionized water.
[0103] The at least one chelating agent of the second polishing
composition may include glycine, EDA, EDTA, citric acid, ammonium
citrate, salts thereof, derivatives thereof and combinations
thereof. The corrosion inhibitor of the second polishing
composition may include BTA, TTA, salts thereof, derivatives
thereof and combinations thereof. Salts may be added to the second
polishing composition or may be formed in situ, such as by an
acid/base type reaction. Salts may be inorganic, organic or
combinations thereof and include cations such as ammonium,
potassium, sodium, calcium and anions such as citrate, oxalate,
succinate and tartrate. A pH adjusting agent includes potassium
hydroxide, ammonium hydroxide or combinations thereof. An oxidizer,
such as hydrogen peroxide and/or abrasive particulates, such as
colloidal silica activated with alumina may be added to the second
polishing composition. In one example, a second polishing
composition includes BTA and glycine. In another example, a second
polishing composition includes BTA, EDA and ammonium citrate. Also,
some of the second polishing compositions contain leveling agents,
such as PEG.
[0104] Electrochemical Mechanical Processing:
[0105] An electrochemical mechanical polishing technique using a
combination of chemical activity, mechanical activity and
electrical activity to remove material and planarize a substrate
surface may be performed as follows. In one embodiment of an
electrochemical mechanical polishing technique, the substrate is
disposed in a receptacle, such as a basin or platen containing a
first electrode and a polishing composition. The polishing
composition forms a passivation layer on the substrate surface. The
passivation layer may chemically and/or electrically insulate
material disposed on a substrate surface.
[0106] A polishing article coupled to a polishing article assembly
containing a second electrode is then disposed in the basin or
platen and physically contacted and/or electrically coupled with
the substrate through the polishing article. Relative motion is
provided between the substrate surface and the conductive article
203 to reduce or remove the passivation layer. A bias from a power
source 224 is applied between the two electrodes. The bias may be
applied by an electrical pulse modulation technique providing at
least anodic dissolution. The bias may be transferred from a
conductive article 203 in the polishing article assembly 222 to the
substrate 208.
[0107] A first ECMP process may be used to remove bulk conductive
material from the substrate surface as shown from FIGS. 4A-4B and
then a second ECMP process to remove residual copper containing
materials as shown from FIGS. 4B-4C. Bulk material is broadly
defined herein as any material deposited on the substrate in an
amount more than sufficient to substantially fill features formed
on the substrate surface. Residual material is broadly defined as
any bulk copper containing material remaining after one or more
polishing process steps. Generally, the bulk removal during a first
ECMP process removes at least about 50% of the conductive layer,
preferably at least about 70%, more preferably at least about 80%,
for example, at least about 90%. The residual removal during a
second ECMP process removes most, if not all the remaining
conductive material disposed on the barrier layer to leave behind
the filled plugs.
[0108] The first ECMP process attributes to the throughput of
substrate manufacturing due to a fast removal rate of the
conductive layer. However, if the first ECMP process is used
solely, too much conductive material may be removed to produce an
under burden. The second ECMP process attributes to the throughput
of substrate manufacturing due to the precise removal the
conductive layer to form level substrate surfaces. However, the
second ECMP process is too slow are removing conducting material to
be solely used. Therefore, the combined first and second ECMP
processes increases throughput and produces high quality planar
substrate surfaces.
[0109] The bulk removal ECMP process may be performed on a first
polishing platen and the residual removal ECMP process on a second
polishing platen of the same or different polishing apparatus as
the first platen. In another embodiment, the residual removal ECMP
process may be performed on the first platen. Any barrier material
may be removed on a separate platen, such as the third platen in
the apparatus described in FIG. 2. For example, the apparatus
described above in accordance with the processes described herein
may include three platens for removing bulk material or comprise
one platen to remove bulk material, a second platen for residual
removal and a third platen for barrier removal, wherein the bulk
and the residual processes are ECMP processes and the barrier
removal is a CMP process. In another embodiment, three ECMP platens
may be used to remove bulk material, residual removal and barrier
removal.
[0110] Referring to FIGS. 4A-4B, the substrate 300 having a
dielectric layer 310 patterned with narrow feature definitions 320
and wide feature definitions 330 is filled with a barrier layer
340, for example, tantalum, and an excess amount of conductive
material 360, for example, copper. The deposition profile of the
excess material includes a high overburden 370, also referred to as
a hill or peak, formed over narrow feature definitions 320 and a
minimal overburden 380, also referred to as a valley, over wide
feature definitions 330.
[0111] The substrate is exposed to a polishing composition
described herein that forms a passivation layer 390 on the
conductive material layer 360. The passivation layer 390 forms on
the exposed conductive material 360 on the substrate surface
including the high overburden 370, peaks, and minimal overburden
380, valleys, formed in the deposited conductive material 360. The
passivation layer 390 chemically and/or electrically insulates the
surface of the substrate from chemical and/or electrical reactions.
The passivation layer is formed from the exposure of the substrate
surface to the corrosion inhibitor and/or other materials capable
of forming a passivating or insulating film, for example, chelating
agents. The thickness and density of the passivation layer can
dictate the extent of chemical reactions and/or amount of anodic
dissolution. For example, a thicker or denser passivation layer 390
has been observed to result in less anodic dissolution compared to
thinner and less dense passivation layers. Thus, control of the
composition of passivating agents, corrosion inhibitors and/or
chelating agents, allow control of the removal rate and amount of
material removed from the substrate surface.
[0112] FIG. 4B illustrates that at least about 50% of the
conductive material 360 was removed after the bulk removal of the
first ECMP process, for example, about 90%. After the first ECMP
process, conductive material 360 may still include the high
overburden 370, peaks, and/or minimal overburden 380, valleys, but
with a reduced proportionally size. However, conductive material
360 may also be rather planar across the substrate surface (not
pictured).
[0113] The substrate surface and a polishing article, such as
conductive polishing article, are contacted with one another and
moved in relative motion to one another, such as in a relative
orbital motion, to remove portions of the passivation layer 390
formed on the exposed conductive material 360, which may also
remove a portion of the underlying conductive material 360.
[0114] The substrate surface and polishing article are contacted at
a pressure less than about 2 pounds per square inch (lb/in.sup.2 or
psi) (13.8 kPa). Removal of the passivation layer 390 and some
conductive material 360 may be performed with a process having a
pressure of about 1 psi (6.9 kPa) or less, for example, from about
0.01 psi (69 Pa) to about 0.5 psi (3.4 kPa). In one aspect of the
process, a pressure of about 0.2 psi (1.4 kPa) or less is used.
[0115] The polishing pressures used herein reduce or minimize
damaging shear forces and frictional forces for substrates
containing low k dielectric materials. Reduced or minimized forces
can result in reduced or minimal deformations and defect formation
of features from polishing. Further, the lower shear forces and
frictional forces have been observed to reduce or minimize
formation of topographical defects, such as dishing and scratches,
and delamination, during polishing. Contact between the substrate
and a conductive polishing article also allows for electrical
contact between the power source and the substrate by coupling the
power source to the polishing article when contacting the
substrate. A region of non-passivated material may be exposed and
removed by anodic dissolution by mechanical abrasion to disturb or
remove the passivation layer on the surface of the substrate.
[0116] A bias is applied to the substrate during contact between
the substrate surface and the conductive polishing article for
anodic dissolution of the conductive material 360 from the
substrate surface. The bias is generally provided to produce anodic
dissolution of the conductive material from the surface of the
substrate at a current density up to about 100 mA/cm.sup.2 which
correlates to an applied current of about 40 amps to process
substrates with a diameter up to about 300 mm. For example, a 200
mm diameter substrate may have a current density from about 0.01
mA/cm.sup.2 to about 50 mA/cm.sup.2, which correlates to an applied
current from about 0.01 A to about 20 A. The invention also
contemplates that the bias may be applied and monitored by volts,
amps and watts. For example, in one embodiment, the power supply
may apply a power between about 0 watts and 100 watts, a voltage
between about 0 V and about 10 V, and a current between about 0
amps and about 10 amps.
[0117] During anodic dissolution under application of the bias, the
substrate surface, i.e., the conductive material layer 360 may be
biased anodically above a threshold potential of the conductive
material, for example, a metal material, on the substrate surface
to "oxidize". When a metal material oxidizes, a metal atom gives up
one or more electrons to the power source and forms metal ions or
cations. The metal ions may then leave the substrate surface and
dissolve into the electrolyte solution. In the case where copper is
the desired material to be removed, cations can have the Cu.sup.1+
or Cu.sup.2+ oxidation state.
[0118] The metal ions may also contribute to the formation of the
thickness and/or density of the passivation layer 390. For example,
the inhibitors and/or chelating agents found in the polishing
composition may complex with the metal ions and the metal ions
become incorporated into the passivation layer 390. Thus, the
presence of the inhibitors and/or chelating agents found in the
polishing composition limit or reduce the electrochemical
dissolution process of the metal ions into the electrolyte, and
further incorporate such metal ions into the passivation layer 390.
It has been observed that the thickness and/or density of the
undisturbed passivation layer may increase after periods of applied
bias for anodic dissolution of conductive materials on the
substrate surface. It is believed that the increase in the
thickness and/or density of the undisturbed passivation layer is
related to the total applied power and is a function of time and/or
power levels. It has also been observed that the undisturbed
passivation layer incorporates metal ions and that the metal ions
may contribute to the thickness and/or density of the passivation
layer.
[0119] The bias may be varied in power and application depending
upon the user requirements in removing material from the substrate
surface. For example, increasing power application has been
observed to result in increasing anodic dissolution. The bias may
also be applied by an electrical pulse modulation technique. Pulse
modulation techniques may vary, but generally include a cycle of
applying a constant current density or voltage for a first time
period, then applying no current density or voltage or a constant
reverse current density or voltage for a second time period. The
process may then be repeated for one or more cycles, which may have
varying power levels and durations. The power levels, the duration
of power, an "on" cycle, and no power, an "off" cycle" application,
and frequency of cycles, may be modified based on the removal rate,
materials to be removed, and the extent of the polishing process.
For example, increased power levels and increased duration of power
being applied have been observed to increase anodic
dissolution.
[0120] In one pulse modulation process for electrochemical
mechanical polishing, the pulse modulation process comprises an
on/off power technique with a period of power application, "on",
followed by a period of no power application, "off". The on/off
cycle may be repeated one or more times during the polishing
process. The "on" periods allow for removal of exposed conductive
material from the substrate surface and the "off" periods allow for
polishing composition components and by-products of "on" periods,
such as metal ions, to diffuse to the surface and complex with the
conductive material. During a pulse modulation technique process it
is believed that the metal ions migrate and interact with the
corrosion inhibitors and/or chelating agents by attaching to the
passivation layer in the non-mechanically disturbed areas. The
process thus allows etching in the electrochemically active
regions, not covered by the passivation layer, during an "on"
application, and then allowing reformation of the passivation layer
in some regions and removal of excess material during an "off"
portion of the pulse modulation technique in other regions. Thus,
control of the pulse modulation technique can control the removal
rate and amount of material removed from the substrate surface.
[0121] The "on"/"off" period of time may be between about 1 second
and about 60 seconds each, for example, between about 2 seconds and
about 25 seconds, and the invention contemplates the use of pulse
techniques having "on" and "off" periods of time greater and
shorter than the described time periods herein. In one example of a
pulse modulation technique, power is applied between about 16% and
about 66% of each cycle.
[0122] Non-limiting examples of pulse modulation technique with an
on/off cycle for electrochemical mechanical polishing of materials
described herein include: applying power, "on", between about 5
seconds and about 10 seconds and then not applying power, "off",
between about 2 seconds and about 25 seconds; applying power for
about 10 seconds and not applying power for 5 seconds, or applying
power for 10 seconds and not applying power for 2 seconds, or even
applying power for 5 seconds and not applying power for 25 seconds
to provide the desired polishing results. The cycles may be
repeated as often as desired for each selected process. One example
of a pulse modulation process is described in commonly assigned
U.S. Pat. No. 6,379,223, which is incorporated by reference herein
to the extent not inconsistent with the claimed aspects and
disclosure herein. Further examples of a pulse modulation process
is described in co-pending U.S. Provisional Patent Application
Serial No. 10/611,805, entitled "Effective Method To Improve
Surface Finish In Electrochemically Assisted Chemical Mechanical
Polishing", filed on Jun. 30, 2003, which is incorporated by
reference herein to the extent not inconsistent with the claimed
aspects and disclosure herein.
[0123] A removal rate of conductive material of up to about 15,000
.ANG./min can be achieved by the processes described herein. Higher
removal rates are generally desirable, but due to the goal of
maximizing process uniformity and other process variables (e.g.,
reaction kinetics at the anode and cathode) it is common for
dissolution rates to be controlled from about 100 .ANG./min to
about 15,000 .ANG./min. In one embodiment of the invention where
the copper material to be removed is less than 5,000 .ANG. thick,
the voltage (or current) may be applied to provide a removal rate
from about 100 .ANG./min to about 5,000 .ANG./min. The substrate is
typically exposed to the polishing composition and power
application for a period of time sufficient to remove at least a
portion or all of the desired material disposed thereon.
[0124] The polishing composition may be varied to control the rate
in which the conductive material is removed. In one embodiment, a
first ECMP process is conducted with a first polishing solution,
thereafter, a second ECMP process is conducted with a second
polishing solution more dilute than the first polishing solution,
for example, the second polishing solution is about 25% the
concentration of the first polishing solution. For example, the
first ECMP composition may comprise: from about 1 wt % to about 10
wt % of phosphoric acid; from about 0.1 wt % to about 6 wt % of the
at least one chelating agent; from about 0.01 wt % to about 1 wt %
of the corrosion inhibitor; from about 0.5 wt % to about 10 wt % of
the salt; from about 0.2 wt % to about 5 wt % of the oxidizer; and
from about 0.05 wt % to about 1 wt % of the abrasive particulates.
The second ECMP composition may comprise: from about 0.25 wt % to
about 5 wt % of phosphoric acid; from about 0.05 wt % to about 3 wt
% of the at least one chelating agent; from about 0.005 wt % to
about 0.5 wt % of the corrosion inhibitor; from about 0.13 wt % to
about 5 wt % of the salt; from about 0.05 wt % to about 3 wt % of
the oxidizer; and from about 0.02 wt % to about 0.5 wt % of the
abrasive particulates. In some embodiments, the first ECMP solution
and second ECMP solution have the similar relative concentrations
of each component except water, whereas the second ECMP solution is
formed by combining de-ionized water to the first ECMP solution,
for example at a volume ratio of about 3 to about 1. In other
embodiments, the first polishing solution and second polishing
solution have the varied relative concentrations of each component
within water.
[0125] Generally, the removal rate of conductive material 360 is
much faster during the first ECMP process than during the second
ECMP process. For example, the first ECMP process removes
conductive material 360 at a rate from about 1,000 .ANG./min to
about 15,000 .ANG./min, while the second ECMP process removes
conductive material 360 at a rate from about 100 .ANG./min to about
8,000 .ANG./min. The second ECMP process is slower in order to
prevent excess metal removal to form topographical defects, such as
concavities or depressions known as dishing 55, as shown in FIG.
1B. Therefore, a majority of the conductive layer 360 is removed at
a faster rate during the first ECMP process than the remaining
conductive layer 360 during the second ECMP process. The two-step
ECMP process increases throughput of the total substrate processing
and while producing a smooth surface with little or no defects.
[0126] Mechanical abrasion by a conductive polishing article
removes the passivation layer that insulates or suppresses the
current for anodic dissolution, such that areas of high overburden
is preferentially removed over areas of minimal overburden as the
passivation layer is retained in areas of minimal or no contact
with the conductive polishing article 203. The removal rate of the
conductive material 360 covered by the passivation layer is less
than the removal rate of conductive material without the
passivation layer. As such, the excess material disposed over
narrow feature definitions 320 and the substrate field 350 is
removed at a higher rate than over wide feature definitions 330
still covered by the passivation layer 390.
[0127] Referring to FIG. 4C, most, if not all of the conductive
layer 360 is removed to expose barrier layer 340 and conductive
trenches 365 by polishing the substrate with a second ECMP process
including a second ECMP polishing solution. The conductive trenches
365 are formed by the remaining conductive material 360. Any
residual conductive material and barrier material may then be
polished by a third polishing step to provide a planarized
substrate surface containing conductive trenches 365, as depicted
in FIG. 4D. The residual conductive material and barrier material
may be removed by a third polishing process, such as a third ECMP
process or a CMP process. An example of a copper polishing process
is disclosed in U.S. patent Publication No. 20030029841 and an
example of a barrier polishing process is disclosed in U.S. patent
Publication No. 20030013306, which are both incorporated herein to
the extent not inconsistent with the claims aspects and disclosure
herein.
[0128] After conductive material and barrier material removal
processing steps, the substrate may then be buffed to minimize
surface defects. Buffing may be performed with a soft polishing
article, i.e., a hardness of about 40 or less on the Shore D
hardness scale as described and measured by the American Society
for Testing and Materials (ASTM), headquartered in Philadelphia,
Pa., at reduced polishing pressures, such as about 2 psi or less.
An example of a suitable buffing process and composition is
disclosed in co-pending U.S. patent application Ser. No.
09/569,968, filed on May 11, 2000, and incorporated herein by
reference to the extent not inconsistent with the invention.
[0129] Optionally, a cleaning solution may be applied to the
substrate after each of the polishing process to remove particulate
matter and spent reagents from the polishing process as well as
help minimize metal residue deposition on the polishing articles
and defects formed on a substrate surface. An example of a suitable
cleaning solution is ElectraClean.TM. commercially available from
Applied Materials, Inc., of Santa Clara, Calif.
[0130] Finally, the substrate may be exposed to a post polishing
cleaning process to reduce defects formed during polishing or
substrate handling. Such processes can minimize undesired oxidation
or other defects in copper features formed on a substrate surface.
An example of such a post polishing cleaning is the application of
Electra Clean.TM., commercially available from Applied Materials,
Inc., of Santa Clara, Calif.
[0131] It has been observed that substrate planarized by the
processes described herein have exhibited reduced topographical
defects, such as dishing, reduced residues, improved planarity, and
improved substrate finish. The processes described herein may be
further disclosed by the examples as follows.
EXAMPLES
[0132] The following non-limiting examples are provided to further
illustrate embodiments of the invention. However, the examples are
not intended to be all-inclusive and are not intended to limit the
scope of the inventions described herein.
Example 1
[0133] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc., of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed onto the first platen
and exposed to a polishing composition of:
[0134] about 6% by volume phosphoric acid;
[0135] about 2% by volume ethylenediamine;
[0136] about 2% by weight ammonium citrate;
[0137] about 0.3% by weight benzotriazole;
[0138] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0139] about 0.45% by volume of hydrogen peroxide;
[0140] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0141] de-ionized water.
[0142] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0143] The substrate was placed onto the second platen and exposed
subsequently exposed to a polishing composition of:
[0144] about 1.5% by volume phosphoric acid;
[0145] about 0.4% by volume ethylenediamine;
[0146] about 0.8% by weight ammonium citrate;
[0147] about 0.25% by weight benzotriazole;
[0148] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 5.4;
[0149] about 0.5% by volume of hydrogen peroxide;
[0150] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0151] de-ionized water.
[0152] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 2
[0153] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0154] about 6% by volume phosphoric acid;
[0155] about 2% by volume ethylenediamine;
[0156] about 2% by weight ammonium citrate;
[0157] about 0.3% by weight benzotriazole;
[0158] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0159] about 0.45% by volume of hydrogen peroxide;
[0160] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0161] de-ionized water.
[0162] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500.ANG..
[0163] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0164] about 1.5% by volume phosphoric acid;
[0165] about 0.4% by volume ethylenediamine;
[0166] about 0.8% by weight ammonium citrate;
[0167] about 0.25% by weight benzotriazole;
[0168] about 0.2% by weight polyethylene glycol;
[0169] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 5.4;
[0170] about 0.5% by volume of hydrogen peroxide;
[0171] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0172] de-ionized water.
[0173] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 3
[0174] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0175] about 6% by volume phosphoric acid;
[0176] about 2% by volume ethylenediamine;
[0177] about 2% by weight ammonium citrate;
[0178] about 0.3% by weight benzotriazole;
[0179] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0180] about 0.45% by volume of hydrogen peroxide;
[0181] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0182] de-ionized water.
[0183] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0184] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0185] about 1.0% by volume phosphoric acid;
[0186] about 0.5% by volume glycine;
[0187] about 0.35% by weight benzotriazole;
[0188] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 4.9;
[0189] about 0.5% by volume of hydrogen peroxide;
[0190] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0191] de-ionized water.
[0192] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 4
[0193] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0194] about 6% by volume phosphoric acid;
[0195] about 2% by volume ethylenediamine;
[0196] about 2% by weight ammonium citrate;
[0197] about 0.3% by weight benzotriazole;
[0198] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0199] about 0.45% by volume of hydrogen peroxide;
[0200] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0201] de-ionized water.
[0202] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0203] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0204] about 0.6% by volume phosphoric acid;
[0205] about 1.0% by volume glycine;
[0206] about 0.35% by weight benzotriazole;
[0207] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 6.1;
[0208] about 0.5% by volume of hydrogen peroxide;
[0209] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0210] de-ionized water.
[0211] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 5
[0212] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0213] about 6% by volume phosphoric acid;
[0214] about 2% by volume ethylenediamine;
[0215] about 2% by weight ammonium citrate;
[0216] about 0.3% by weight benzotriazole;
[0217] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0218] about 0.45% by volume of hydrogen peroxide;
[0219] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0220] de-ionized water.
[0221] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0222] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0223] about 0.6% by volume phosphoric acid;
[0224] about 1.5% by volume glycine;
[0225] about 0.35% by weight benzotriazole;
[0226] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 6.1;
[0227] about 0.5% by volume of hydrogen peroxide;
[0228] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0229] de-ionized water.
[0230] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 6
[0231] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0232] about 6% by volume phosphoric acid;
[0233] about 2% by volume ethylenediamine;
[0234] about 2% by weight ammonium citrate;
[0235] about 0.3% by weight benzotriazole;
[0236] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0237] about 0.45% by volume of hydrogen peroxide;
[0238] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0239] de-ionized water.
[0240] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0241] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0242] about 0.6% by volume phosphoric acid;
[0243] about 2.0% by volume glycine;
[0244] about 0.35% by weight benzotriazole;
[0245] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 6.1;
[0246] about 0.5% by volume of hydrogen peroxide;
[0247] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0248] de-ionized water.
[0249] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 7
[0250] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0251] about 6% by volume phosphoric acid;
[0252] about 2% by volume ethylenediamine;
[0253] about 2% by weight ammonium citrate;
[0254] about 0.3% by weight benzotriazole;
[0255] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0256] about 0.45% by volume of hydrogen peroxide;
[0257] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0258] de-ionized water.
[0259] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0260] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0261] about 1.5% by volume phosphoric acid;
[0262] about 0.4% by volume ethylenediamine;
[0263] about 0.8% by weight ammonium citrate;
[0264] about 0.25% by weight benzotriazole;
[0265] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 5.4;
[0266] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0267] de-ionized water.
[0268] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 8
[0269] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0270] about 6% by volume phosphoric acid;
[0271] about 2% by volume ethylenediamine;
[0272] about 2% by weight ammonium citrate;
[0273] about 0.3% by weight benzotriazole;
[0274] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0275] about 0.45% by volume of hydrogen peroxide;
[0276] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0277] de-ionized water.
[0278] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0279] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0280] about 1.5% by volume phosphoric acid;
[0281] about 0.4% by volume ethylenediamine;
[0282] about 0.8% by weight ammonium citrate;
[0283] about 0.25% by weight benzotriazole;
[0284] about 0.2% by weight polyethylene glycol;
[0285] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 5.4;
[0286] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0287] de-ionized water.
[0288] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 9
[0289] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0290] about 6% by volume phosphoric acid;
[0291] about 2% by volume ethylenediamine;
[0292] about 2% by weight ammonium citrate;
[0293] about 0.3% by weight benzotriazole;
[0294] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0295] about 0.45% by volume of hydrogen peroxide;
[0296] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0297] de-ionized water.
[0298] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0299] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0300] about 1.0% by volume phosphoric acid;
[0301] about 0.5% by volume glycine;
[0302] about 0.35% by weight benzotriazole;
[0303] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 4.9;
[0304] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0305] de-ionized water.
[0306] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 10
[0307] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0308] about 6% by volume phosphoric acid;
[0309] about 2% by volume ethylenediamine;
[0310] about 2% by weight ammonium citrate;
[0311] about 0.3% by weight benzotriazole;
[0312] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0313] about 0.45% by volume of hydrogen peroxide;
[0314] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0315] de-ionized water.
[0316] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0317] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0318] about 0.6% by volume phosphoric acid;
[0319] about 1.0% by volume glycine;
[0320] about 0.35% by weight benzotriazole;
[0321] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 6.1;
[0322] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0323] de-ionized water.
[0324] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 11
[0325] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0326] about 6% by volume phosphoric acid;
[0327] about 2% by volume ethylenediamine;
[0328] about 2% by weight ammonium citrate;
[0329] about 0.3% by weight benzotriazole;
[0330] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0331] about 0.45% by volume of hydrogen peroxide;
[0332] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0333] de-ionized water.
[0334] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0335] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0336] about 0.6% by volume phosphoric acid;
[0337] about 1.5% by volume glycine;
[0338] about 0.35% by weight benzotriazole;
[0339] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 6.1;
[0340] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0341] de-ionized water.
[0342] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
Example 12
[0343] A copper plated substrate with 300 mm diameter was polished
and planarized using the following polishing composition within a
modified cell on a REFLEXION.RTM. system, available from Applied
Materials, Inc. of Santa Clara, Calif. A substrate having a copper
layer of about 11,500 .ANG. thick on the substrate surface with a
step height of about 6,000 .ANG. was placed into the first platen
and exposed to a polishing composition of:
[0344] about 6% by volume phosphoric acid;
[0345] about 2% by volume ethylenediamine;
[0346] about 2% by weight ammonium citrate;
[0347] about 0.3% by weight benzotriazole;
[0348] from about 2% to about 6% by volume 40% KOH solution to
provide a pH of about 5;
[0349] about 0.45% by volume of hydrogen peroxide;
[0350] about 0.15% by weight of silica (SiO.sub.2) abrasive
particles; and
[0351] de-ionized water.
[0352] A polishing article was contacted with the substrate at
about 0.2 psi and a bias of about 3 volts was applied during the
process. The substrate was polished and examined. The copper layer
thickness was reduced to about 1,500 .ANG..
[0353] The substrate was placed into the second platen and exposed
subsequently exposed to a polishing composition of:
[0354] about 0.6% by volume phosphoric acid;
[0355] about 2.0% by volume glycine;
[0356] about 0.35% by weight benzotriazole;
[0357] from about 0.5% to about 3% by volume 40% KOH solution to
provide a pH of about 6.1;
[0358] about 0.7% by weight of silica (SiO.sub.2) abrasive
particles; and
[0359] de-ionized water.
[0360] A polishing article was contacted with the substrate at
about 0.1 psi at a bias of about 1.5 volts was applied during the
process. The substrate was polished and examined. The excess copper
layer formerly on the substrate surface was removed to leave behind
the barrier layer and the copper trench.
[0361] While the foregoing is directed to embodiments of the
present 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.
* * * * *