U.S. patent application number 10/020082 was filed with the patent office on 2003-05-29 for pads for cmp and polishing substrates.
Invention is credited to West, Thomas E. JR..
Application Number | 20030100250 10/020082 |
Document ID | / |
Family ID | 26692987 |
Filed Date | 2003-05-29 |
United States Patent
Application |
20030100250 |
Kind Code |
A1 |
West, Thomas E. JR. |
May 29, 2003 |
Pads for CMP and polishing substrates
Abstract
Pads and methods of making the pads for applications such as
polishing substrates and chemical mechanical planarization of
substrates are provided. The pads are substantially porous and
substantially hard for improved polishing and planarization
properties. Pads according to some embodiments of the present
invention have beneficial properties like those of standard
technology porous pads and beneficial properties like those of
standard technology hard pads.
Inventors: |
West, Thomas E. JR.;
(Portolla, CA) |
Correspondence
Address: |
LARRY WILLIAMS
122 CALISTOGA ROAD, PMB-301
SANTA ROSA
CA
95409-3702
US
|
Family ID: |
26692987 |
Appl. No.: |
10/020082 |
Filed: |
December 11, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60340819 |
Oct 29, 2001 |
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Current U.S.
Class: |
451/288 |
Current CPC
Class: |
B24B 37/24 20130101;
B24D 11/001 20130101 |
Class at
Publication: |
451/288 |
International
Class: |
B24B 007/22 |
Claims
What is claimed is:
1. A pad for chemical mechanical planarization of substrates for
electronic device fabrication, the pad having a Shore D hardness
greater than about 47, and the pad having a density of about 0.5
grams per cubic centimeter to about 0.7 grams per cubic
centimeter.
2. The pad of claim 1, wherein the pad has a Shore D hardness from
about 47 to about 57.
3. The pad of claim 1, wherein the pore structure is sufficient for
transporting a polishing slurry for chemical mechanical
planarization.
4. The pad of claim 3, wherein the pore structure is substantially
homogeneous throughout the pad.
5. The pad of claim 3, wherein the pad has a Shore D hardness from
about 51 to about 54.
6. The pad of claim 1, wherein the pad has a Shore D hardness from
about 51 to about 54 and a density in the range of about 0.54 grams
per cubic centimeter to about 0.62 grams per cubic centimeter.
7. A pad comprising: a non-woven felt, the felt having a density
greater than about 0.29 grams per cubic centimeter; and a polymer
resin; wherein, the felt is impregnated with the resin so that the
pad has a Shore D hardness greater than about 47, a density from
about 0.5 grams per cubic centimeter to about 0.7 grams per cubic
centimeter, and a compressive modulus greater than about 70%.
8. The pad of claim 7, wherein the felt has a density of about 0.32
grams per cubic centimeter.
9. The pad of claim 7, wherein the pad has a Shore D hardness from
about 47 to about 57.
10. The pad of claim 7, wherein the felt has a density of about
0.32+/-0.03 grams per cubic centimeter and the pad has a Shore D
hardness from about 47 to about 57.
11. The pad of claim 7, wherein the resin comprises at least one of
polyvinylchloride, polyvinylfluoride, nylon, fluorocarbon,
polycarbonate, polyester, polyacrylate, polyether, polyethylene,
polyamide, polyurethane, polystyrene, polypropylene, and copolymers
and mixtures thereof.
12. The pad of claim 7, wherein the pad has a Shore D hardness from
about 51 to about 54.
13. A pad for chemical mechanical planarization of substrates for
electronic device fabrication, the pad comprising: a non-woven felt
comprising polyester fibers, the felt having a denier of about 2,
the felt having a density of about 0.32+/-0.03 grams per cubic
centimeter; and a polymer resin comprising polyurethane, the resin
having a 100% modulus value of about 300 kg/cm to about 400 kg/cm;
wherein, the felt is impregnated with the resin so that the pad has
a Shore D hardness from about 47 to about 57, a density of about
0.5 grams per cubic centimeter to about 0.7 grams per cubic
centimeter, a polyurethane to fiber ratio of about 45:55, a
compressive modulus greater than about 70%, a substantially
homogeneous, substantially open pore structure sufficient for
transporting amounts of a polishing slurry effective for CMP.
14. A pad according to claim 13, wherein the pad has air
permeability greater than about 20 (cubic centimeters)/((square
centimeter)(minute)).
15. A pad according to claim 13, wherein the pad has air
permeability in the range of about 24 to about 34 (cubic
centimeters)/((square centimeter)(minute)).
16. A pad according to claim 15, wherein the resin has a 100%
modulus value of about 350 kg/cm, the ratio of weight percent fiber
to weight percent resin is about 55:45, the felt comprises
polyester, and the resin comprises polyurethane.
17. A method of making a hard porous pad, the pad having a Shore D
hardness from about 47 to about 57 and a density of about 0.5 grams
per cubic centimeter to about 0.7 grams per cubic centimeter, the
method comprising the steps of: providing a non-woven felt of
polymer fibers, the felt having a density greater than about 0.29
grams per cubic centimeter; providing a resin; impregnating the
felt with the resin so that the ratio of weight percent fiber to
weight percent resin is in the range from about 50:50 to about
65:35.
18. The method of claim 17, wherein the felt has a density of
0.32+/-0.03 grams per cubic centimeter.
19. The method of claim 17, wherein the resin has a 100% modulus
value of about 300 kg/cm to about 400 kg/cm.
20. The method of claim 17, wherein the ratio of weight percent
fiber to weight percent resin is about 55:45.
21. The method of claim 17, wherein the felt has a density of
0.32+/-0.03 grams per cubic centimeter, the resin has a 100%
modulus value of about 350 kg/cm, the ratio of weight percent fiber
to weight percent resin is about 55:45.
22. The method of claim 21, wherein the felt comprises
polyester.
23. The method of claim 21, wherein the resin comprises
polyurethane.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims benefit of provisional U.S.
patent application Docket Number TWI-002, filed on Oct. 29, 2001,
entitled "PADS FOR CMP AND POLISHING SUBSTRATES." This application
is related to provisional U.S. patent application Docket Number
TWI-004, filed on Oct. 29, 2001, entitled "POLISHING PADS AND
MANUFACTURING METHODS." The contents of all of these applications
are incorporated herein by this reference in their entirety.
TECHNICAL FIELD
[0002] This invention relates to pads for applications such as
chemical mechanical planarization (CMP) and polishing of substrates
such as semiconductor substrates, wafers, metallurgical samples,
memory disk surfaces, optical components, lenses, and wafer masks.
More particularly, the present invention relates to CMP pads and
pads for polishing and methods of manufacturing pads having
improved properties for fabrication of electronic devices.
BACKGROUND
[0003] Processes employing CMP or polishing techniques have been
widely used to planarize the surface of wafers during the various
stages of device fabrication in order to improve yield,
performance, and reliability of the fabrication process. In fact,
CMP has become essentially indispensable for the fabrication of
advanced integrated circuits.
[0004] Integrated circuits are chemically and physically integrated
into a substrate by patterning regions in the substrate and layers
on the substrate. To achieve high yields, it is usually necessary
to recreate a substantially flat substrate after processing steps
that leave topographic features on the surface of the wafer,
features such as surface irregularities, bumps, troughs, and
trenches.
[0005] Various types of pads have been developed in efforts to meet
the needs of CMP processes and polishing processes. For a more
detailed discussion of polishing pads see PCT application
WO96/15887, the specification of which is incorporated herein by
reference. Other representative examples of polishing pads are
described in U.S. Pat. Nos. 4,728,552, 4,841,680, 4,927,432,
4,954,141, 5,020,283, 5,197,999, 5,212,910, 5,297,364, 5,394,655
and 5,489,233, the specifications of which are also each
incorporated herein in their entirety by reference.
[0006] Although polishing pads are in extensive use, a need remains
for improved polishing pads which provide effective planarization
across electronic device substrates and have improved polishing
efficiency, increased removal rates, improved uniformity across the
substrate, and longer pad life for lower cost of ownership. In
addition, there is a need for new pads that can tolerate the higher
temperatures that are needed for advanced CMP processes.
Furthermore, there is a need for new pads that possess some of the
best properties of different types of pads so that the overall
performance of the pad is better than that of the standard
technology pads.
SUMMARY
[0007] This invention pertains to improve pads for applications
such as polishing substrates and CMP of substrates and related
methods. The present invention seeks to overcome one or more of the
deficiencies of the standard technologies for polishing and/or
planarizing substrates.
[0008] One aspect of the invention is a pad for applications such
as polishing substrates and CMP of substrates. In one embodiment,
the pad is substantially hard and has a substantially open pore
structure. In preferred embodiments, the pore structure is
sufficient for transporting a polishing slurry at a rate that is
effective for CMP. Preferably, the pore structure is substantially
homogeneous throughout the pad.
[0009] Another embodiment of the present invention is a pad for CMP
of substrates for electronic device fabrication. The pad includes a
non-woven felt and a polymer resin. The felt is impregnated with
the resin so that the pad has a Shore D hardness from about 45 to
about 65, a density in the range of about 0.5 grams per cubic
centimeter to about 0.7 grams per cubic centimeter, and a
compressive modulus greater than about 70%.
[0010] Another embodiment of the present invention is a pad for
polishing substrates for electronic device fabrication. The pad
includes a non-woven felt having a density of about 0.29 to about
0.35 grams per cubic centimeter and a polymer resin. The felt is
impregnated with the resin so that the pad has a Shore D hardness
from about 47 to about 57, a density in the range of about 0.5
grams per cubic centimeter to about 0.7 grams per cubic centimeter,
and a compressive modulus greater than about 70%.
[0011] It is to be understood that the invention is not limited in
its application to the details of construction and to the
arrangements of the components set forth in the following
description or illustrated in the figures. The invention is capable
of other embodiments and of being practiced and carried out in
various ways. In addition, it is to be understood that the
phraseology and terminology employed herein are for the purpose of
description and should not be regarded as limiting.
[0012] As such, those skilled in the art will appreciate that the
conception, upon which this disclosure is based, may readily be
utilized as a basis for the designing of other structures, methods
and systems for carrying out aspects of the present invention. It
is important, therefore, that the claims be regarded as including
such equivalent constructions insofar as they do not depart from
the spirit and scope of the present invention.
[0013] Further, the purpose of the foregoing abstract is to enable
the Patent Office and the public generally, and especially the
scientists, engineers and practitioners in the art who are not
familiar with patent or legal terms or phraseology, to determine
quickly from a cursory inspection the nature and essence of the
technical disclosure of the application. The abstract is not
intended to define the invention of the application, which is
measured by the claims, nor is the abstract intended to be limiting
as to the scope of the invention in any way.
[0014] The above and still further features and advantages of the
present invention will become apparent upon consideration of the
following detailed descriptions of specific embodiments thereof,
especially when taken in conjunction with the accompanying
figures.
DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a SEM photograph of a pad according to an
embodiment of the present invention.
[0016] FIG. 2 is a SEM photograph of a standard technology hard
pad.
[0017] FIG. 3 is a SEM photograph of a standard technology semi
soft pad.
[0018] FIG. 4 is a graph showing planarization data for a pad
according to an embodiment of the present invention and data for a
standard technology pad.
[0019] FIG. 5 is a graph showing copper planarization efficiency
for a pad according to an embodiment of the present invention.
[0020] FIG. 6 is a graph showing polishing results using a pad
according to an embodiment of the present invention.
DESCRIPTION
[0021] The operation of embodiments of the present invention will
be discussed below, primarily, in the context of chemical
mechanical planarization. However, it is to be understood that
embodiments in accordance with the present invention may be used
for general applications of substrate polishing such as grinding,
lapping, shaping and polishing of semiconductor substrates, wafers,
metallurgical samples, memory disk surfaces, optical components,
lenses, and wafer masks.
[0022] An embodiment of the present invention is an improved
polishing pad for removing material from a substantially solid
surface. More particularly, one embodiment of the present invention
is a polishing pad for applications such as chemical mechanical
planarization such as that used as part of integrated circuit
manufacturing processes. Another embodiment of the present
invention includes methods for performing chemical mechanical
planarization. Still another embodiment of the present invention
includes methods for fabricating polishing pads.
[0023] Embodiments of the present invention include an improved
polishing pad for applications such as chemical mechanical
planarization. One embodiment of the present invention is a pad for
chemical mechanical planarization of substrates for electronic
device fabrication; the pad is substantially hard and the pad has a
substantially homogeneous pore structure sufficient for
transporting amounts of CMP slurry effective for CMP
processing.
[0024] In some embodiments, the pad includes a multiplicity of
fibers and a polymer resin. The fibers are arranged so as to form a
non-woven mass such as a felt. The polymer resin is applied so as
to impregnate the fibers and, consequently, form the pad. For
embodiments of the present invention, the resulting pad has
properties of the standard technology porous pads and properties of
the standard technology hard pads. In other words, embodiments of
the present invention are substantially porous and substantially
hard so that the pads have one or more of the beneficial CMP
characteristics of standard technology porous pads and standard
technology hard pads. Specifically, pads according to embodiments
of the present invention are harder than the standard technology
porous pads and more porous than the standard technology hard
pads.
[0025] Some embodiments of the present invention have a Shore D
hardness from about 45 to about 65 and all subranges subsumed
therein. A preferred embodiment has a Shore D hardness from about
47 to about 57 and all subranges subsumed therein. A more preferred
embodiment has a Shore D hardness from about 51 to about 54.
[0026] Polishing pads according to embodiments of the present
invention have porosities that are higher than that for standard
technology hard pads and lower than that for standard technology
soft pads. The porosity of the pad is related to the density of the
pad. Generally, a high porosity corresponds to a low-density and
vice versa. Specifically, polishing pads according to the present
invention have densities in the range of about 0.5 grams per cubic
centimeter to about 0.7 grams per cubic centimeter. In a preferred
embodiment, the polishing pad has a density of about 0.58+/-0.04
grams per cubic centimeter. Typically, the high-density is
preferable for embodiments of the present invention, provided the
porosity of the pad is sufficient for transporting slurry. In other
words, it is preferable for the pad to be capable of transporting
amounts of slurry that may be required for the polishing process or
CMP process for which the pad is being used.
[0027] The air permeability of a pad for polishing or CMP can be
considered an indication of the porosity and the pore structure.
Specifically, air permeability is determined by pad properties such
as the pore size, porosity, and amount of open pore structure. Some
embodiments of the present invention have air permeabilities
greater than or equal to about 20 (cubic centimeters)/((square
centimeter)(minute)). One of the preferred embodiments of the
present invention has air permeabilities in the range of about 24
to about 34 (cubic centimeters)/((square centimeter)(minute)) and
all subranges subsumed therein.
[0028] Furthermore, some embodiments of the present invention have
pore sizes in the range from about 5 micrometers to about 150
micrometers, and all ranges subsumed therein. In some of the
preferred embodiments, the pore structure is substantially
homogeneous throughout the pad.
[0029] A wide range of polymer resins may be used in embodiments of
the present invention. Suitable resins include resins such as, for
example, polyvinylchloride, polyvinylfluoride, nylons,
fluorocarbons, polycarbonate, polyester, polyacrylate, polyether,
polyethylene, polyamide, polyurethane, polystyrene, polypropylene,
and mixtures thereof. The selection of the resin will depend upon
the desired properties of the pad. Preferred embodiments of the
present invention include resins that have high hardness values.
This means that for resin impregnated felt pads according to
preferred embodiments of the present invention, the hardness of the
resin is higher than that of resins that are typically used for
resin impregnated felt pads according to the standard technology.
Typical resins are commercially available from a number of
vendors.
[0030] The hardness of the resin is related to the 100% modulus
value of the resin. This modulus provides a measure of the tensile
strength of the resin. One embodiment of the present invention has
a 100% modulus value of about 300 kg/cm to about 400 kg/cm. A
preferred embodiment of the present invention uses a polyurethane
resin having a 100% modulus value of about 350 kg/cm. For purposes
of comparison, one of the standard technology porous pads uses a
polyurethane resin having a 100% modulus value of about 200
kg/cm.
[0031] Various manufacturing techniques can be used to produce
polishing pads according to embodiments of the present invention.
In one embodiment, the polishing pad includes non-woven fibers
comprising polyester and a polymer resin comprising polyurethane.
Desirable properties for polishing pads according to embodiments of
the present invention can be produced using polyester fibers having
a denier of about 2. Those skilled in the art know that embodiments
of the present invention can also be made using other deniers, such
as for example, deniers in the range of about 1.5 to about 3.0.
[0032] Desirable properties for polishing pads according to
embodiments of the present invention can be incorporated into the
polishing pads by increasing the ratio of fiber to polymer resin in
the polishing pad. For some embodiments of the present invention,
the ratio of polyester fiber to polyurethane resin is in the range
of from about 50:50 to about 65:35, and all ratios and ratio ranges
subsumed therein. In other words, the polyester makes up from about
50% to about 65% and subranges subsumed therein. The polyurethane
resin makes up from about 50% to about 35% and subranges subsumed
therein. Preferred embodiments of the present invention have ratios
of polyester to polyurethane of about 55:45.
[0033] Notably, the traditional thinking among those skilled in the
art is that pad hardness increases with an increase in the resin
content. However, some embodiments of the present invention show
higher hardness with an increase in the fiber content. This means
that some embodiments of the present invention have fiber to resin
ratios that are contrary to the standard thinking of those skilled
in the art. In other words, the ratio of felt to resin is higher in
some embodiments of the present invention than that found in the
standard technology pads. Specifically, embodiments of the present
invention have higher ratios of polyester fiber to polyurethane
than is typically thought desirable for good pad
characteristics.
[0034] Table 1 summarizes several physical properties of some
embodiments of polishing pads according to the present
invention.
1 TABLE 1 Property Suitable Preferred Pad Density gm/cc 0.5-0.7
0.58 +/- 0.04 Fiber to Polymer Resin Ratio 50:50-65:35 55:45
Hardness, Shore D >47 51-54 Hardness, Shore A 89-98 Felt Density
gm/cc 0.32 Pore Size Range um 5-150 Compressibility % 1.8
Resiliency % 70-100 >80
[0035] Conventional methods were used for measuring the properties
of the pads.
[0036] In some instances, the performance of pads according to the
present invention has been found to be better than that of standard
hard pads. Specifically, using pads according to the present
invention have been shown to result in defectivities of about 5 to
about 10 for wafers of 200 mm diameter for defects >0.2
micrometers measured on a Tencor.RTM. 6420. However, the typical
performance for a standard hard pad results in a defectivity of
about 20 or greater, under substantially the same process
conditions.
[0037] Reference is now made to FIG. 1 wherein there is shown a
photograph taken by SEM of a pad according to an embodiment of the
present invention. The pad includes a polyester fiber felt
impregnated with a polyurethane resin. FIG. 1 shows a surface and
side section view of the pad at a magnification of about
100.times.; the open pore structure can be seen in the photograph.
The pad shown in FIG. 1 has a Shore D hardness of about 51 to about
54, a density of about 0.59 grams per cubic centimeter, a
compressibility of about 1.8 percent, and a rebound of about 85
percent.
[0038] For comparison, similar measurements were made for one of
the standard technology hard pads. Reference is now made to FIG. 2
wherein there is shown a photograph taken by SEM of the standard
technology hard pad made of polyurethane. FIG. 2 shows the surface
of the standard technology hard pad at a magnification of about
100.times.. The SEM photograph shows that the standard technology
hard pad has less pore structure than the embodiment of the present
invention shown in FIG. 1. The standard technology hard pad shown
in FIG. 2 has a Shore D hardness of about 52-62, a density of 0.75
grams per cubic centimeter, a compressibility of 2.1 percent, and a
rebound of about 73 percent. The pad shown in FIG. 2 does not
include a felt.
[0039] In addition, similar measurements were made for a standard
technology semi-soft pad, also referred to as a porous pad.
Reference is now made to FIG. 3 wherein there is shown a photograph
taken by SEM of one of the standard technology semi soft pads at a
magnification of about 41.times.. The semi soft pad has a Shore D
hardness of about 30 to about 35, a density of about 0.37 grams per
cubic centimeter, a compressibility of about 2.4 percent, and a
rebound of about 76 percent.
[0040] It appears that pads according to the present invention have
some properties that are intermediate to those of standard
technology semi soft pads and standard technology hard pads. As a
specific example, the hardness of pads according to embodiments of
the present invention is intermediate to that for the standard
technology semi soft pad and the standard technology hard pad. As a
result, the performance of pads according to the present invention
is, in some ways, superior to those of the semi soft standard
technology pads and the standard technology hard pads.
[0041] Table 2 shows process conditions and results from CMP
processes for tungsten using pads according to embodiments of the
present invention. The CMP process was performed with a standard
commercially available slurry, EKC 3550 W slurry.
2TABLE 2 Flow Down Table Carrier Rate Removal Non- Wafer Force
Speed Speed (ml/ Rate Uniformity ID (psi) (rpm) (rpm) min) (A/min)
(%) A 6 110 95 110 3910 3.5 B 6 110 110 110 3830 4.1 C 5 110 95 110
2690 9.7 D 7 90 95 110 4200 2.9 E 6 110 95 110 4950 5.2 F 6 110 95
80 4100 4.2 G 6 110 95 140 3860 4.9 H 6 90 110 110 2670 11 I 6 110
95 110 3670 7.5 J 7 90 95 110 3540 3.8
[0042] Embodiments of the present invention have another advantage
over the standard technology pads in terms of erosion during
processes such as CMP of tungsten damascene structures. Table 3
shows erosion data for pads according to the present invention and
the standard technology pads. In general, pads according to present
invention produced less erosion of the oxide during the
planarization of tungsten damascene structures.
3TABLE 3 0% Over 25% Over 50% Over 100% Over Pad Type Polish Polish
Polish Polish Embodiment Of 400 420 480 650 Present Invention
Standard Technology 210 650 910 1000
[0043] The planarization capabilities of pads according to the
present invention have been measured. In addition, similar
measurements have been performed for the standard technology pads.
The experimental results, in general, show that pads according to
the present invention have superior planarization capability over
that of the standard technology pads. Some of the experimental
results are presented in FIG. 4. The results in FIG. 4 are for an
oxide planarization process. The x-axis represents the amount, in
Angstroms, of oxide removed; the y-axis represents the remaining
step height in Angstroms. These results are for features of 100
micrometer lines and spaces and were obtained using a down force of
4.5 psi. The points resented by diamonds, connected by the solid
line are data for a pad according to an embodiment of the present
invention. The points represented by squares, connected by the
dashed line, are data for a standard technology hard pad. For these
measurements, the pad according to the present invention had lower
remaining step height for the amount of oxide removed. In other
words, the pad according to the present invention is more efficient
than the standard technology pad in terms of producing a planar
surface. For the results shown in FIG. 4, the pad according to the
present invention included a polyester felt impregnated with a
polyurethane resin; the pad had a Shore D hardness of about 51 to
about 54, a density of about 0.59 grams per cubic centimeter, a
compressibility of about 1.8 percent, and a rebound of about 85
percent.
[0044] Planarization capabilities of pads according to the present
invention were also measured for copper planarization. FIG. 5 shows
step height, in Angstroms, as a function of removed field copper
for planarization using pads according to the present invention.
The process conditions were down force 3 psi, table speed 105 rpm,
carrier speed 100 rpm, slurry flow rate 100 ml/minute, and back
pressure 0 psi. For the results shown in FIG. 5, the pad according
to the present invention included a polyester felt impregnated with
a polyurethane resin; the pad had a Shore D hardness of about 51 to
about 54, a density of about 0.59 grams per cubic centimeter, a
compressibility of about 1.8 percent, and a rebound of about 85
percent.
[0045] Reference is now made to FIG. 6 wherein there is shown
performance data for pads according to the present invention. The
process data are for a tungsten CMP process using a commercially
available slurry, EKC 3550 W slurry. The x-axis represents the
wafer number. The y-axis represents either removal rate in
angstroms per minute, non-uniformity in percent, or defectivity.
The closed diamonds represent tungsten removal rates, WRR.
[0046] For this set of experiments, the tungsten removal rate
varies from about 3800 A/min to about 4800 A/min. The triangles
represent removal rates for titanium, TiRR. The open diamonds
represent data points for tungsten removal nonuniformities, WNU.
The tungsten nonuniformity for this set of experiments have values
less than about 10% and in some instances less than or equal to
about 5%. The measured defectivities, shown as solid ovals, for
this set of experiments are in the range of about 5 to about 10 for
wafers having diameters of 200 mm. For the results shown in FIG. 6,
the pad according to the present invention included a polyester
felt impregnated with a polyurethane resin; the pad had a Shore D
hardness of about 51 to about 54, a density of about 0.59 grams per
cubic centimeter, a compressibility of about 1.8 percent, and a
rebound of about 85 percent.
[0047] Another advantage of embodiments of the present invention is
that the pads are particularly suitable for some of the more
advanced CMP processes where higher polishing speeds are required.
This improvement, seen in some embodiments of the present
invention, is believed to result from the greater stability, such
as thermal stability, of the pads according to the present
invention.
[0048] Pads made according to embodiments of the present invention
have been shown to have superior performance compared to that of
standard technology pads for several planarization test. Pads
according to embodiments of the present invention have, in general,
20 to 25% higher removal rates with the exact same process
parameters as solid polyurethane pads, i.e., standard technology
hard pads. Pads according to embodiments of the present invention
have, in general, a factor of about 2 times to about 10 times lower
defectivity than for the standard technology hard pads. Pads
according to embodiments of the present invention have, in general,
40% lower slurry use requirement for maintaining a removal rate
that is insensitive to slurry flow. Pads according to embodiments
of the present invention, in general, have a long operating life
for the pad, typically, about 2 times to about three times that of
the standard technology hard pads. Pads according to embodiments of
the present invention, in general, require less diamond pad
conditioning between each wafer than is required for standard
technology hard pads. The required down force is lower for
embodiments of the present invention and only one or two sweeps
between wafers may be need. Whereas, for standard technology hard
pads, the pad conditioners wear out much more quickly than for pads
according to embodiments of the present invention. Pads according
to embodiments of the present invention, in general, have lower
oxide erosion than the standard technology hard pads.
[0049] In addition, pads according to the present invention are
capable of providing satisfactory polishing characteristics in
addition to having substantially longer lifetimes.
[0050] While there have been described and illustrated specific
embodiments of the invention, it will be clear that variations in
the details of the embodiments specifically illustrated and
described may be made without departing from the true spirit and
scope of the invention as defined in the appended claims and their
legal equivalents.
* * * * *