U.S. patent application number 10/551457 was filed with the patent office on 2006-09-07 for polishing pad, process for producing the same and method of polishing therewith.
Invention is credited to Hiroshi Nakagawa, Masaya Nishiyama, Yasuo Shimamura, Masao Suzuki, Masato Yoshida.
Application Number | 20060199473 10/551457 |
Document ID | / |
Family ID | 33162772 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060199473 |
Kind Code |
A1 |
Suzuki; Masao ; et
al. |
September 7, 2006 |
Polishing pad, process for producing the same and method of
polishing therewith
Abstract
Provided is a polishing pad comprising a fiber including organic
fiber and a matrix resin holding the fiber, wherein at least the
organic fiber is exposed on the work material-side surface thereof
at least after dressing. The polishing pad suppresses generation of
minute polishing scratches on the work material and allows flat
polishing at low load. It in also possible to manage the polishing
end point of the work material without generation of polishing
scratch with its optical detection system monitoring the polishing
state of work material. Thus, for example, it is possible to polish
substrates under a small load on the interlayer insulating film and
give products superior in flatness in semiconductor device
manufacturing processes and thus, the polishing pad according to
the invention may be used easily in the next-generation dual
damascene method.
Inventors: |
Suzuki; Masao; (Chiba,
JP) ; Nakagawa; Hiroshi; (Ibaraki, JP) ;
Yoshida; Masato; (Ibaraki, JP) ; Nishiyama;
Masaya; (Ibaraki, JP) ; Shimamura; Yasuo;
(Ibaraki, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Family ID: |
33162772 |
Appl. No.: |
10/551457 |
Filed: |
April 2, 2004 |
PCT Filed: |
April 2, 2004 |
PCT NO: |
PCT/JP04/04820 |
371 Date: |
September 30, 2005 |
Current U.S.
Class: |
451/8 ; 451/41;
451/527 |
Current CPC
Class: |
B24D 18/0027 20130101;
B24B 37/24 20130101 |
Class at
Publication: |
451/008 ;
451/041; 451/527 |
International
Class: |
B24B 49/00 20060101
B24B049/00; B24B 7/30 20060101 B24B007/30; B24D 11/00 20060101
B24D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2003 |
JP |
2003-100376 |
Apr 7, 2003 |
JP |
2003-103477 |
Apr 8, 2003 |
JP |
2003-103624 |
Claims
1. A polishing pad comprising a fiber including organic fiber and a
matrix resin holding the fiber, wherein at least the organic fiber
is exposed on the work material-side surface thereof.
2. A polishing pad comprising a fiber including organic fiber and a
matrix resin holding the fiber, wherein at least the organic fiber
is exposed on the work material-side surface after dressing
treatment.
3. The polishing pad according to claim 1 or 2, wherein the matrix
resin contains at least one thermoplastic resin.
4. The Polishing pad according to claim 1 or 2, wherein the matrix
resin is a semicrystalline thermoplastic resin.
5. The polishing pad according to claim 1 or 2, wherein an
elastomer is dispersed in the matrix resin.
6. The polishing pad according to claim 5, wherein the elastomer
has a glass transition point of 0.degree. C. or less.
7. The polishing pad according to claim 1 or 2, wherein the fiber
is an aromatic polyamide.
8. The polishing pad according to claim 1 or 2, wherein the
polishing pad contains an inorganic fiber in an amount of 1 to 50
wt %.
9. The polishing pad according to claim 1 or 2, wherein the organic
fiber has a diameter of 1 mm or less.
10. The polishing pad according to claim 1 or 2, wherein the
organic fiber has a length of 1 cm or less.
11. The polishing pad according to claim 1 or 2, wherein polishing
particles are held by the organic fiber exposed on the work
material-side surface.
12. The polishing pad according to claim 1 or 2, wherein the
maximum length of the exposed organic fiber is 0.1 mm or less.
13. The polishing pad according to claim 12, wherein the exposed
organic fiber is a polyester fiber.
14. The polishing pad according to claim 12, wherein a chopped
polyester fiber is dispersed in the matrix resin.
15. The polishing pad according to claim 12, wherein a polyester
nonwoven fabric is laminated in the matrix resin.
16. The polishing pad according to and claim 1 or 2 that is useful
for optical detection of the polishing end point during polishing
of the work material surface, wherein the polishing pad contains a
substantially non-foam matrix resin containing an organic fiber in
an amount of 1 to 20 wt %, has the functions of transporting and
retaining polishing slurry particles, and allows transmission of a
light having a wavelength in the range of 190 to 3,500 nm.
17. The polishing pad according to claim 1 or 2 that is useful for
optical detection of the polishing end point during polishing of
the work material surface, wherein the polishing pad contains a
region transmitting a light having a wavelength in the range of 190
to 3,500 nm that is made of a substantially non-foam matrix resin
containing an organic fiber in an amount of 1 to 20 wt % and has
the functions of transporting and retaining polishing slurry
particles.
18. The polishing pad according to claim 16, wherein the organic
fiber is an aramide fiber
19. A method for producing a polishing pad for use as attached to a
polishing table for flattening a work material's polishing plane,
comprising a step of obtaining a mixture of a fiber including
organic fiber and a matrix composition containing a thermoplastic
resin by blending, a step of palletizing or tabletizing the
mixture, and a step of molding the pellet or tablet into a plate or
a sheet shape by extrusion or injection molding.
20. A method for producing a polishing pad for use as attached to a
polishing table for flattening a work material's polishing plane,
comprising a step of impregnating a fibrous base material
containing organic fiber with a matrix resin composition to form a
fibrous resin-impregnated sheet-shaped base material. and a step of
laminating fibrous sheet-shaped base materials including the
fibrous resin-impregnated sheet-shaped base material and molding
the laminate with heating and pressure.
21. The method for producing a polishing pad according to claim 19
or 20, further including a step of exposing the fiber on the
surface.
22. A polishing method for polishing a work material's polishing
plane, comprising polishing a work material pressing the polishing
plane of the work material to the organic fiber-exposed face of the
polishing pad according to claim 1 or 2, and sliding the work
material and the pad relatively while supplying a polishing slurry
between the work material's polishing plane and the polishing
pad.
23. The polishing method for polishing a work material's polishing
plane according to claim 22, wherein the work material polishing
plane is a laminate of a conductor layer as well as a copper layer
formed on an insulation layer having a dielectric constant of 2.7
or less on which wiring and trenches are found.
24. A polishing method for detecting the polishing end point
optically by using the polishing pad according to claim 16.
Description
TECHNICAL FIELD
[0001] The present invention relates to a polishing pad for use in
chemical mechanical polishing (CMP), for example, in semiconductor
device-manufacturing technologies and for precision polishing in
hard disk-manufacturing technologies, a production method thereof,
and a polishing method using the polishing pad.
BACKGROUND ART
[0002] In the current trend toward increase in packaging density of
ultralarge-scale integrated circuits, various microfabrication
technologies are now under research and development. The design
rule is already in the sub-half micron order. One of the
technologies under development for satisfying the strict
requirements in microfabrication is CMP (chemical mechanical
polishing) technology. The technology is effective in completely
flattening the layer to be exposed to light, alleviating the load
of exposure technology, and stabilizing the production yield at a
high level in the processes for manufacturing semiconductor
devices, and the polishing is performed in the following way. The
film on the surface of a work material is removed precisely to a
predetermined thickness, by pressing the work material to a
polishing pad and sliding the polishing pad and the work material
relatively while supplying a CMP polishing slurry in state of
slurry between the work material and the polishing pad. Thus, CMP
is an indispensable technology, for Example, for flattening of
interlayer-insulating and BPSG films, shallow trench isolation, and
others.
[0003] Form or non-foam organic resin polishing pads have been used
as the polishing pads for use in the CMP technology (See Claims and
background of the invention in Japanese Patent Application National
Publication (Laid-Open) No. 8-511210). Commonly used, for example,
is urethane foam resin sheet having concentric or grid-patterned
trenches.
[0004] There is a problem of damage (polishing scratch) on the
polishing plane by abrasive and polishing waste. It is very
effective to reduce the rigidity of polishing pad for reduction of
polishing scratch when a common polishing pad of a foam or non-foam
organic resin is used. However, the decrease in rigidity often
results in decrease in polishing speed and deterioration of the
dishing of trench area. It was difficult to satisfy these
properties at the same time.
[0005] Although Al wire has been used in the wiring process,
currently, embedded wiring by the dual damascene process, which
uses Cu, a metal lower in resistivity, as the wiring metal and a
low-dielectric constant material as the interlayer insulating film,
is the mainstream process.
[0006] In the dual damascene process, it is quite important to
select the polishing slurry and the polishing pad adequately. In
particular, the metal, which is more chemically reactive and softer
than the interlayer insulating film, often causes defects by
polishing scratch and corrosion. On the other hand, dishing occurs
more frequently on the material having smaller easiness to
deformation, i.e., elastic modulus. However, increase in the
elastic modulus of pad generally leads to increase in pad rigidity
and consequently to defects such as polishing scratch.
[0007] In addition, recent application of a low-dielectric constant
material to the interlayer insulating film is accompanied by
deterioration in the mechanical properties of insulation layer and
the adhesion with metal and is a factor causing defects during
polishing, and thus, there is a need for a polishing system having
lower mechanical load demands during polishing.
[0008] Further, it is necessary to control the polishing amount
adequately during CMP polishing in the shallow trench isolation
stop metal wiring polishing step in dual damascene process, and
interlayer insulating film-polishing step. Examples of the methods
include strict control of the polishing period, detection of the
variation in torque of the motor driving the polishing machine due
to the change in the friction between pad and wafer during
polishing, and measurement of the electrostatic capacity of work
material. Recently however, polishing machines equipped to
optically detect changes in the wafer surface state during
polishing are increasingly available, and technology for
controlling the wafer polishing state by irradiating a laser beam
or infrared ray from a polishing machine via a polishing pad onto
the polishing plane of a wafer and detecting the reflected beam
once again via the polishing pad by a sensor in the polishing
machine is becoming predominantly popular. The optical method is
useful especially in the shallow trench isolation step and the dual
damascene method, because a barrier film is exposed on the wafer
surface at the end of polishing and a high reflectance change can
be obtained if a light with a suitable wavelength is used for
detection. In the step of polishing an insulation film having no
barrier film, it is possible to detect the polishing amount from
the interference between the reflected beam from wafer surface and
the reflected beam from the silicon layer beneath insulation film.
A polishing pad of a polyurethane foam resin plate having a
transparent window allowing transmission of light formed in part
thereof is used as a typical example of the polishing pad using
such an optical method. Also proposed are a method for making a
polishing pad of a non-foam resin, such as polyurethane,
polycarbonate nylon, acrylic polymer or polyester, transmit light
(e.g., U.S. Pat. No. 5,605,760). However, these polishing pads have
problems demanding-reduction of polishing scratch during CMP
polishing and preservation of polishing speed while optical
detection of end point, and in particular in the damascene, as
described above it is important to reduce generation of the defects
caused by polishing scratch and corrosion.
DISCLOSURE OF THE INVENTION
[0009] The present invention is completed after intensive studies
on the structure of polishing pads to solve the problems above.
[0010] The present invention provides a polishing pad that allows
efficient flattening and formation of metal wiring in the CMP
technology used in flattening of interlayer insulating film, BPSG
film, insulation film for shallow trench isolation and the like,
and formation of metal wiring in the semiconductor
device-manufacturing process, and suppression of the scratches on
polishing plane and the defects of insulation layer, a production
method thereof, and a polishing method using the polishing pad. It
also provides a polishing pad that has a light transmission
suitable for use in the polishing step of irradiating light via a
polishing pad onto the surface of a work material such as
semiconductor wafer, detecting the change in reflectance, and
controlling the polishing end point and suppresses generation of
polishing scratch on the work material, and a polishing method for
polishing by using the polishing pad.
[0011] The present invention relates to (1) a polishing pad
comprising a fiber including organic fiber and a matrix resin
holding the fiber, wherein at least the organic fiber is exposed on
the work material-side surface thereof.
[0012] The present invention also relates to (2) a polishing pad
comprising a fiber including organic fiber and a matrix resin
holding the fiber, wherein at least the organic fiber is exposed on
the work material-side surface after dressing treatment.
[0013] The present invention relates to (3) the polishing pad
described in (1) or (2), wherein the matrix resin contains at least
one thermoplastic resin.
[0014] The present invention relates to (4) the polishing pad
described in any one of (1) to (3), wherein the matrix resin is a
semicrystalline thermoplastic resin.
[0015] The present invention relates to (5) the polishing pad
described in any one of (1) to (4), wherein an elastomer is
dispersed in the matrix resin.
[0016] The present invention relates to (6) the polishing pad
described in (5), wherein the elastomer has a glass transition
point of 0.degree. C. or less.
[0017] The present invention relates to (7) the polishing pad
described in any one of (1) to (6), wherein the fiber is an
aromatic polyamide.
[0018] The present invention relates to (8) the polishing pad
described in any one of (1) to (7), wherein the polishing pad
contains an inorganic fiber in an amount of 1 to 50 wt %.
[0019] The present invention relates to (9) the polishing pad
described in any one of (1) to (8), wherein the organic fiber has a
diameter of 1 mm or less.
[0020] The present invention relates to (10) the polishing pad
described in any one of (1) to (9), wherein the organic fiber has a
length of 1 cm or less.
[0021] The present invention relates to (11) the polishing pad
described in any one of (1) to (10), wherein polishing particles
are held by the organic fiber exposed on the work material-side
surface.
[0022] The present invention relates to (12) the polishing pad
described In any one of (1) to (11), wherein the maximum length of
the exposed organic fiber is 0.1 mm or less.
[0023] The present invention relates to (13) the polishing pad
described in (12), wherein the exposed organic fiber is a
polyester.
[0024] The present invention relates to (14) the polishing pad
described in (12) or (13), wherein a chopped polyester fiber is
dispersed in the matrix resin.
[0025] The present invention relates to (15) the polishing pad
described in (12) or (13), wherein polyester nonwoven fabrics are
laminated in the matrix resin.
[0026] The present invention relates to (16) the polishing pad
described in any one of (1), (2) to (4), (7), and (9) to (11) that
is useful for optical detection of the polishing end point during
polishing of the work material surface, wherein the polishing pad
contains a substantially non-foam matrix resin containing an
organic fiber in an amount of 1 to 20 wt %, has the functions of
transporting and retaining polishing slurry particles, and allows
transmission of a light having a wavelength in the range of 190 to
3,500 nm.
[0027] The present invention relates to (17) the polishing pad
described in any one of (1), (2) to (4), (7), and (9) to (11) that
which is useful for optical detection of the polishing end point
during polishing of the work material surface, wherein the
polishing pad contains a region transmitting a light having a
wavelength in the range of 190 to 3,500 nm that is made of a
substantially non-foam matrix resin containing an organic fiber in
an amount of 1 to 20 wt % and has the functions of transporting and
retaining polishing slurry particles.
[0028] The present invention relates to (18) the polishing pad
described in (16) or (17), wherein the organic fiber is an aramide
fiber.
[0029] The present invention relates to (19) a method for producing
a polishing pad for use as attached to a polishing table for
flattening a work material's polishing plane comprising a step of
obtaining a mixture of a fiber including organic fiber and a matrix
composition containing a thermoplastic resin by blending, a step of
pelletizing or tabletizing the mixture, and a step of molding the
pellet or tablet into a plate or a sheet shape by extrusion or
injection molding.
[0030] The present invention relates to (20) a method for producing
a polishing pad for use as attached to a polishing table for
flattening a work material's polishing plane comprising a step of
impregnating a fibrous base material containing organic fiber with
a matrix resin composition to form a fibrous resin-impregnated
sheet-shaped base material, and a step of laminating fibrous
sheet-shaped base materials including the fibrous resin-impregnated
sheet-shaped base material and molding the laminate with heating
and pressure.
[0031] The present invention relates to (21) the method for
producing a polishing pad described in (19) or (20), further
including a step of exposing the fiber on the surface.
[0032] The present invention relates to (22) a polishing method for
polishing a work material's polishing plane, comprising polishing
the work material by pressing the polishing plane of the work
material to the organic fiber-exposed face of the polishing pad
described in any one of (1) to (18) and sliding the work material
and the pad relatively while supplying a polishing slurry between
the work material's polishing plane and the polishing pad.
[0033] The present invention relates to (23) the polishing method
for polishing a work material's polishing plane described in (22),
wherein the work material's polishing plane is a laminate of a
conductor layer as well as a copper layer formed on an insulation
layer having a dielectric constant of 2.7 or less on which wiring
and trenches are formed.
[0034] The present invention relates to (24) a polishing method for
detecting the polishing end point optically by using the polishing
pad described in any one of (16) to (18).
[0035] The surface-exposed organic fiber relaxes the stress between
the abrasive and the foreign materials in polishing slurry and the
work material during polishing to prevent generation of scratches
on the surf ace of the work material. In addition, although foam
holes and small and large trenches on the surface in the
conventional polishing pads made only of a common resin are
responsible for transportation and retention of the abrasive in the
polishing slurry, in the polishing pad according to the present
invention the surface-exposed organic fiber is responsible for the
transportation and retention of the abrasive in the polishing
slurry and plays a role of improving polishing speed and uniformity
in flatness.
BEST MODE FOR CARRYING OUT THE INVENTION
[0036] The polishing pad according to the present invention has a
structure consisting of a fiber including organic fiber and a
matrix resin holding the fiber. The organic fiber may be included
as all or part of the fiber, and the fiber may contain an inorganic
fiber such as glass fiber in addition to the primary organic
fiber.
[0037] The structure of the pad is not particularly limited, if the
pad has at least the organic fiber exposed on the work
material-side surface of the pad. In the present invention, the
phrase "the organic fiber is exposed" includes the case of the work
material-side surface after dressing treatment, i.e., means that at
least organic fiber in exposed at least during use on.
[0038] Typical examples of the structure of polishing pad include a
structure wherein a chopped fiber is dispersed in a matrix resin, a
structure wherein woven or nonwoven fabrics of a fiber are
laminated in a matrix resin, and the like.
[0039] Any one of common thermosetting and thermoplastic resins may
be used without limitation as the matrix resin holding a fiber in
the polishing pad according to the present invention. Preferable
are resins relatively higher in elastic modulus, for example, those
having a room-temperature elastic modulus of 0.1 GPa or more, more
preferably 0.5 GPa or more after curing. A resin with a smaller
elastic modulus may give a polishing plane poorer in flatness.
[0040] Examples of the thermosetting resins favorably used include
epoxy resins such as bisphenol A epoxy resins, cresol novolak epoxy
resin, unsaturated polyester resins, acrylic resins, polyurethane
resins, and the like. These resins may be used alone or in
combination of two or more. When an epoxy resin is used as the
thermosetting resin, it is usually blended with a curing agent, a
curing accelerator, and the like. Examples of the curing agents
include dicyandiamide, organic acids, organic acid anhydrides,
polyamine, and the like. While examples of the curing accelerators
include 2-ethyl-4-methylimidazole and the like.
[0041] Examples of the thermoplastic resins include polycarbonate,
polymethyl methacrylate, AS (acrylonitrile-styrene copolymer), ABS
(acrylonitrile-butadiene rubber-styrene copolymer), polyethylene,
polypropylene, polybutene, 4-methyl-pentene-1, ethylene-propylene
copolymer, ethylene-vinyl acetate copolymer, polyester, polyamide,
polyamide-imide, polyacetal, and the like. These resins may be used
alone or in combination of two or more. In particular, it is
possible to obtain a polishing pad superior in abrasion resistivity
and higher in durability by using a semicrystalline thermoplastic
polymer resin as the matrix resin.
[0042] The first embodiment of the polishing pad according to the
present invention is a polishing pad containing at least one
thermoplastic resin in the matrix resin. The matrix resin is not
particularly limited, if it contains at least one thermoplastic
resin, and a matrix resin containing thermoplastic resin as the
principal component is preferable.
[0043] The second embodiment of the polishing pad according to the
present invention is a polishing pad in which the maximum length of
the organic fiber exposed out of the work material-side surface is
0.1 mm or less. The maximum length of the exposed organic fiber is
the maximum value among the lengths of the exposed region of the
fibers that are substantially embedded in the polishing pad
surface. It is practically possible to determine the maximum length
by observing five or more points on the pad surface, for example,
by using a SEM (scanning electron microscope).
[0044] The third embodiment of the polishing pad according to the
present invention is a polishing pad useful for optical detection
of the polishing end point during polishing of the work material
surface, part or all of which is substantially made of a non-foam
matrix resin containing organic fiber in an amount of 1 to 20 wt %
that transmits a light having a wavelength in the range of 190 to
3,500 nm, and which has functions of transporting and holding
polishing slurry particles.
[0045] In particular in the first embodiment, an additive, such as
crosslinked or uncrosslinked elastomer, crosslinked polystyrene or
crosslinked polymethyl methacrylate, may be dispersed together with
the thermoplastic resin in the matrix resin. Addition of a
thermoplastic elastomer and a low-crosslinked elastomer is more
preferable. The elastomer is not particularly limited, if it has a
glass transition point of not higher than room temperature, and an
elastomer having a glass transition point of 0.degree. C. or lower
is more preferable. Examples of thereof include olefinic
elastomers, styrene elastomers, urethane elastomers, ester
elastomers, and elastomers of alkenyl aromatic compound-conjugated
diene copolymer or polyolefin copolymer, and the like. Increase in
the amount of the elastomer added results in a persistent resin
higher in impact resistance and increase in the friction force
between pad surface and metal.
[0046] A wide range of materials that can be processed into the
fibrous form including aramide, polyester, polyimide, and the i.e.,
may be used as the organic fibers in the polishing pad according to
the present invention. Two or more materials selected from them may
be used in combination.
[0047] From the points of the durability of pad and the retention
of abrasive particles by the fiber, use of an aramide fiber, i.e.,
an aromatic polyamide fiber, entirely or partially as the principal
component is preferable, and use of an aramide fiber alone is more
preferable. It is because the aramide fiber, which is higher in
tensile strength than other common organic fibers and thus remains
on the surface in a greater amount when the surface of the
polishing pad according to the present invention is roughened
mechanically for exposure of the fiber, is effective for retention
of abrasive particles. In addition, use of it also improves the
durability of polishing pad and lengthens its lifetime during use.
Use of an aramide fiber is particularly preferable in the first and
third embodiments.
[0048] There are two kinds of aramide fibers, para-and meta-aramide
fibers, but the para-aramide fiber is more preferable, as it is
higher in dynamic strength and lower in hygroscopicity than the
meta-aramide fiber. A commercially available product,
poly-p-phenylene terephthalamide fiber and poly-p-phenylene
diphenylether terephthalamide fiber, may be used as the
para-aramide fiber.
[0049] It is also preferable to use polyester as the principal
component of the organic fiber for adjustment of the maximum
exposure length and the surface roughness. It is because use of a
polyester fiber allows reduction in the maximum exposure length, as
the polyester fiber has a smaller shearing strength than hard
fibers when the polishing pad is processed for exposure of the
fiber out of the polishing pad. Use of it is particularly
preferable for the polishing pad in the second embodiment.
Alternatively, when other hard fiber such as aramide fiber or
polyimide fiber is used, the maximum exposure length is controlled
by reduction in the diameter of the whetstone particles used. The
surface roughness of the pad depends on the diameter of the
whetstone particles then, and thus, the diameter of the particles
influences on the irregularity of the pad surface and thus on
polishing speed. On the contrary, when a polyester fiber is used,
the exposure length hardly varies, no matter which whetstone is
used among those different in particle diameter. Thus, it becomes
possible to adjust the surface roughness of the pad itself freely
while maintaining the fiber length to a constant value.
[0050] The hard fibers described above may be used as mixed with a
polyester fiber. The content of the polyester fiber then is
preferably 40 to 100 wt %, more preferably 70 to 100 wt %, and
still more preferably 80 to 100 wt %. Increase in the content of
polyester fiber may lead to decrease in the thickness of the
fiber-exposed layer, while increase in the content of hard fiber
may lead to increase in the thickness of the layer and
deterioration in the flatness of polishing plane.
[0051] The diameter of the organic fiber is preferably 1 mm or
less, more preferably 200 .mu.m or less, still more preferably 1 to
200 .mu.m, and still more preferably 5 to 150 .mu.m. An excessively
large diameter may lead to an excessively high mechanical strength,
occasionally causing polishing scratch and inadequate dressing.
Alternatively, an excessively smaller diameter may lead to
deterioration in handling efficiency and in pad durability because
of insufficiency in strength.
[0052] The length of the fiber length is not particularly limited,
but in the case of a polishing pad containing chopped fiber
dispersed in a resin, the length is preferably 10 mm or less, more
preferably 5 mm or less, and still more preferably, 0.1 to 3 mm. An
excessively shorter length may lead to lack of maintaining
effectively the exposed fibers on the pad when the pad surface is
roughened mechanically, while an excessively longer length may make
molding of a mixture of a resin and the fiber difficult because of
the increase in viscosity of the mixture. Both of the short fibers
chopped to a specific length and a mixture of several fibers
different in length may be used.
[0053] In addition, the fiber surface may be previously roughened
mechanically or chemically or modified, for example, with a
coupling agent for improvement in compatibility with the resin.
Bundles of chopped short fibers adhered to each other with an
extremely small amount of resin may be used for convenience in
handling. However, the resin for adhesion may be added in an amount
that the short fibers can be dispersed in the matrix resin by the
heat or the shearing force applied during agitation with the matrix
resin.
[0054] As for a polishing pad of woven or nonwoven fabric laminate,
if a non-woven fabric is used, a sheet produced by binding fibers
of 1 mm or more in length similar to above by the adhesive force of
the fiber itself or with an adhesive may be used as the non-woven
fabric. The adhesive is, for example, an epoxy resin adhesive such
as water-soluble epoxy resin binder, or the like. When an adhesive
is used, the amount is not particularly limited, but is preferably
3 to 20 parts, more preferably 5 to 15 parts by weight, with
respect to 100 parts by weight of the fiber. Alternatively when a
woven fabric of long fiber is used, the weaving pattern of the
fabric in not particularly limited. A polishing pad containing a
laminate of such fabrics in particularly favorable as the polishing
pad in the second embodiment of the present invention.
[0055] The unit weight of the nonwoven and woven fabrics above is
preferably 36 to 100 g/m.sup.2 and more preferably 55 to 72
g/m.sup.2.
[0056] The content of the organic fiber is not particularly
limited, but, is preferably 1 to 50 wt % in the entire pad, more
preferably 1 to 20 wt %, and still more preferably 5 to 20 wt %
when a chopped fiber is used entirely in the pad. Decrease in the
fiber amount may tend to result in significant increase in the
number of polishing scratches on the polishing plane, while
increase thereof in deterioration in molding efficiency. On the
other hand, in the case of a woven or nonwoven fabric, the content
is preferably 50 wt % or more and more preferably 60 to 80 wt
%.
[0057] In the third embodiment particularly, the content of organic
fiber in the optically transparent region should be in the range
that does not inhibit light transmittance and allows detection of
the polishing state of the wafer. Thus, the content of organic
fiber is preferably 1 to 20 wt % and more preferably 2 to 10 wt %
in the entire polishing pad. A smaller fiber content may lead to
increase in the number of the polishing scratches on polishing
plane, while a greater content to deterioration in molding
efficiency.
[0058] The polishing pad may be produced, for example, by a method
for dispersing a fiber in a matrix resin composition and molding
the resulting mixture, or a method for preparing a prepreg by
impregnating a woven or non-woven fabric containing fiber with a
varnish of resin and laminating such prepregs, but is not limited
thereto.
[0059] Hereinafter, methods of producing the polishing pad
according to the present invention will be described.
[0060] The first production method includes a step of obtaining a
mixture of a fiber including organic fiber and a matrix resin
composition by blending, a step of pelletizing or tabletizing the
mixture, and a step of molding the pellet or tablet into a plate or
sheet shape by extrusion or injection molding. The second
production method include a step of impregnating a fibrous base
material containing organic fiber with a matrix resin composition
to form a fibrous resin-impregnated sheet-shaped base material, and
a step of laminating fibrous sheet-shaped base materials including
the fibrous resin-impregnated sheet-shaped base material and
molding the laminate with heating and pressure. The fibrous base
material preferably contains a polyester fiber primarily.
[0061] The matrix resin composition for production of the polishing
pad according to the present invention may be prepared and mixed
with a fiber in and any one of known methods without limitation
particularly.
[0062] In the first production method, if a chopped fiber is to be
dispersed in a matrix resin composition as it is, matrix-forming
resin compositions are blended (dry blended) uniformly, for
example, in a Henschel Mixer, super mixer, tumble mixer, ribbon
blender, or the like, and melt kneaded, for example, in a single
screw extruder, biaxial extruder, Banbury mixer, or the like. Then,
the fiber is added and melt-blended. The mixture is then cooled,
and tabletized or pelletized. The composition should be dehydrated
thoroughly by drying, if water is used for cooling.
[0063] It is possible to form a sheet- or plate-shaped molding, by
extruding once again the tablet or pellet obtained from an
extruding molding machine through a die and rolling the extruded
resin with a roll. Alternatively in another production method, the
sheet- or plate-shaped molding is prepared, by injection-molding in
a metal mold, instead of the extrusion molding above.
[0064] When the matrix resin composition is a liquid thermosetting
resin composition, it in possible to mold the resin composition, by
dispersing a predetermined amount of chopped fiber in the liquid
thermosetting resin composition, pouring the dispersion in a mold
or the like, removing air bubbles therein under reduced pressure,
and then heat curing the dispersion. The molding may also be
produced by pouring the dispersion into a mold while heating under
pressure.
[0065] The second production method may also be performed by any
one of known methods, and is particularly suitable for production
of the polishing pad in the second embodiment. For example, if a
woven or nonwoven fabric in used as the fibrous base material, the
fibrous resin-impregnated sheet-shaped base materials, or
alternatively a fibrous resin-impregnated sheet-shaped base
material and a fibrous non-resin-impregnated sheet-shaped base
material (woven or nonwoven fabric), are prepared. It is possible
to obtain a molding by integrating these base materials by molding
with heating and pressure. It is also preferable then to make some
organic fibers exposed on the surface by placing a fibrous
non-resin-impregnated sheet-shaped base material at least on one
surface.
[0066] The fibrous resin-impregnated sheet-shaped base material is
produced by impregnating a fibrous non-resin-impregnated
sheet-shaped base material with a resin composition and normally
called a prepreg. The method for producing the prepreg is not
particularly limited, and the prepreg can be produced by preparing
a varnish by dissolving matrix resin composition components in an
organic solvent, impregnating a fibrous non-resin-impregnated
sheet-shaped base material with the varnish, and heating and drying
the resulting base material. The solvent for use is not
particularly limited, if it dissolves the resin composition
uniformly. Examples thereof include ketones such as
methylethylketone, methylisobutylketone, and acetone; lower
alcohols such as ethyl alcohol, propyl alcohol, and isopropyl
alcohol; amides such as dimethylformamide and formamide; and the
like, and these solvents may be used in combination. The content of
fiber in the fibrous resin-impregnated sheet-shaped base material
is preferably 60 to 140 parts by weight, more preferably 90 to 120
parts, with respect to 100 parts by weight of the total of resin
composition and adhesive.
[0067] The rate of the fibrous non-resin-impregnated sheet-shaped
base material in polishing pad is decided properly, taking into
consideration the fiber content in the polishing pad, in particular
the content of the organic fiber on the surface to be pressed to
the work material. By the method, it is not necessary to change the
resin content during production of the prepreg, for alteration of
the fiber content in the polishing pad, but the fiber content can
be modified only by changing the rate of the fibrous
non-resin-impregnated sheet-shaped base material used.
[0068] In molding with heating and pressure, the heating
temperature is generally 150 to 200.degree. C. and the pressure is
50 to 500 kPa. These parameters may be changed suitably according
to the kind and the content of the thermosetting resin used.
[0069] The final polishing pad product in obtained by processing
the molding as needed into a shape suitable for the specific
polishing table shape of the polishing machine. For example, a
final polishing pad product can be produced by cutting the
sheet-shaped molding into a circular form.
[0070] The thickness of the entire polishing pad is preferably 0.1
to 5 mm and more preferably 0.5 to 2 mm. Trenches for transporting
polishing slurry and polishing waste may be formed on the polishing
plane of the pad in the concentric or grid pattern, for example, by
using an NC lathe.
[0071] For obtaining the polishing pad according to the present
invention having at least organic fiber exposed on the work
material-side surface, the fiber is exposed by treating the work
material-side surface of the pad as needed. One of the methods for
exposing the fiber is dressing treatment, a method for exposing the
fiber by scraping off the surface resin of the pad by using a
whetstone such as diamond particles. Other material such as wire
brush, metal scraper, resin brush, or glass or ceramic plate may be
used instead of the whetstone.
[0072] The condition of using these materials should be decided
carefully for adjustment of the exposure length of fiber. The
maximum exposure fiber length depends largely on the rigidity of
fiber, but use of a polyester fiber in the pad allows easy
adjustment thereof to a smaller length.
[0073] The maximum length of the exposed region of the organic
fiber exposed on surface is practically 1 mm or leas, more
preferably 200 .mu.m or less, still more preferably 1 to 200 .mu.m,
and still more preferably 10 to 150 .mu.m. Shorter exposed organic
fiber may be less effective in holding polishing slurry, leading to
decrease in polishing speed, while longer organic fiber may give an
adverse influence on the flatness of the polishing place.
[0074] In particular in the polishing pad in the second embodiment
of the present invention, the maximum length of the exposed organic
fiber is 0.1 mm or less. Although satisfactory if it is 0.1 mm or
less, the maximum exposure length is preferably 1 to 50 .mu.m and
more preferably to 25 .mu.m. Increase in the maximum exposure
length leads to deterioration in flatness, while decrease leads to
deterioration in polishing speed.
[0075] The organic fiber exposed on the work material-side surface
retains the polishing particles (abrasive) efficiency contained in
the polishing slurry described below during polishing.
[0076] Hereinafter, the polishing pad in the third embodiment of
the present invention will be described. The polishing pad allows
optical detection of the polishing amount of the work material,
controls the and point, and suppresses generation of the polishing
scratches during polishing while preserving high polishing speed
and uniformity. Such a configuration can be obtained by modifying
the structure of polishing pad, resin composition, filling
material, or the like.
[0077] In the structure of the polishing pad, the polishing pad is
made of a material allowing transmission of a light having a
wavelength in the range of 190 to 3,500 nm, or part of the
polishing pad is made of the optically transparent material. In the
latter case, for example, a small piece of the optically
transparent polishing pad is inserted as a transparent window in
part of another polishing pad that does not transmit light
sufficiently.
[0078] Because the polishing pad or part thereof allows
transmission of a light having a wavelength in the range of 190 to
3,500 nm, it is possible to manage the polishing end point by
irradiating the light via the polishing pad on a polishing place of
a work material and measuring the change in reflectance. In the
present invention, the term, the polishing pad or part thereof
allowing transmission of a light having a wavelength in the range
of 190 to 3,500 nm, means that the polishing pad or part thereof
has a transmittance of the light at the wavelength at 10 to 100%
before the organic fiber is exposed. The transmittance is
preferably 30 to 100%.
[0079] Resins relatively higher in elastic modulus are favorable as
the matrix resin for use as the optically transparent material, and
the resins described above may be used without restriction. In
particular, use of a semicrystalline thermoplastic polymer resin is
effective in producing a polishing pad superior in abrasion
resistivity and higher in durability. The resin in preferably in
the form substantially free from foam holes. It is because a resin
containing foam holes inhibits light transmission and detection of
polishing state of a wafer. An aramide fiber is preferably selected
as the single or primary component of the organic fiber.
[0080] The polishing pad is produced in a similar manner to the
production method described above, and specifically, each molding
in cut into a polishing pad in the predetermined shape (e.g.,
circular shape) corresponding to the polishing table shape of
polishing machine, or the molding is processed into a small piece
and inserted as an optically transparent window into a hole in
other polishing pad lower in light transmission, to give a
polishing pad allowing optical detection. In the latter case, it is
preferable to prepare a polishing pad lower in light transmission
having a hole for insertion of the window also with a resin plate
or the like containing an organic fiber, to enhance the
advantageous effects of the present invention, but the fiber
content is not particularly limited. The window inserted should be
in contact with the work material on the pad surface during
polishing. It is because, if the window and the work material are
significantly separated from each other, the polishing slurry may
flow into the space and inhibit optical detection by scattering the
transmitted light. The shape of the window is not particularly
limited, but the size thereof should be large enough to ensure an
optical path allowing proper operation of the
photoirradiator/detector sensor system placed in the polishing
machine for optical detection, and the window preferably has an
area of approximately 0.1 to 10% with respect to the entire of the
polishing pad surface.
[0081] Hereinafter, the polishing method by using the polishing pad
according to the present invention will be described. The polishing
method according to the present invention is a method for polishing
a work material's polishing plane by pressing the polishing plane
of the work material to the organic fiber-exposed face of any one
of the polishing pads according to the present invention described
above and sliding the pad and the work material relatively while
supplying a polishing slurry between the work material's polishing
plane and the polishing pad.
[0082] Examples of the work materials include the substrate
carrying a silicon oxide film formed, for example, by the
TEOS-plasma CVD method after a device pattern is formed thereon
with a silicon nitride film and the Si exposed area is etched in
the shallow trench isolation step, and the substrate having an
interlayer insulating film having viaholes and wiring trenches
formed by dry etching a barrier conductive film that cover the
openings and the internal wall completely formed thereon and
additionally a Cu film formed thereon in the state without any
opening in the damascene method.
[0083] The CMP polishing slurry for use in the polishing method
according to the present invention is not specified here, but an
example thereof for insulation films is a polishing slurry prepared
by dispersing a composition consisting of cerium oxide (ceria) or
silicon oxide (silica) particles and a dispersant in a dispersion
medium such as water and adding additives additionally. The
polishing slurry for metal layers such as of Cu is, for example, a
polishing slurry prepared by dispersing abrasive ouch as silica,
alumina, ceria, titania, zirconia, or germania, additives, and an
anticorrosive in water and adding peroxides additionally. Colloidal
silica or alumina particles are particularly favorable as the
abrasive. The content of the abrasive particles is preferably 0.1
to 20 wt %. The abrasive particles may be prepared in any way, but
the average diameter is preferably 0.01 to 1.0 .mu.m. The abrasive
particles having an average diameter of less than 0.01 .mu.m leads
to decrease in polishing speed, while that of more than 1.0 .mu.m
causes an increased number of scratches.
[0084] The polishing machine is not particularly limited, and, for
example, a disk polishing machine or a linear polishing machine may
be used. For example, common polishing machines having a holder for
holding a work material and a polishing table for attaching a
polishing pad that is connected to a variable frequency motor may
be used. An example is a polishing machine EP0111, manufactured by
Ebara Corporation.
[0085] In particular in the polishing method by using a polishing
pad of the third embodiment allowing optical detection of polishing
end point, the polishing end point is managed by irradiating a
light at a wavelength of 190 to 3,500 nm via the polishing pad onto
the polishing plane of the work material and detecting the change
in reflectance while polishing the work material's polishing plane
by sliding the polishing pad relatively to the work material as
described above.
[0086] For use of the polishing pad of the third embodiment, the
polishing machine should have a device for irradiation of a laser
beam and detection of the reflected beam that is connected to the
polishing table for attaching the polishing pad, as in the MIRRA
polishing machine manufactured by Applied Materials U.S. The
polishing condition is not particularly limited, but is preferably
optimized according to the polishing work material. For accurate
polishing, the polishing end point is managed in the polishing
machine by detecting exposure of the silicon nitride film in the
shallow trench isolation step or exposure of the barrier film in
the damascene method while measuring reflection of the light
irradiated onto the wafer surface. The program for managing the
progress of polishing is installed previously to the polishing
machine.
[0087] For fixing the polishing pad according to the present
invention to the polishing table of polishing machine, an adhesive
such as double-faced adhesive tape may be used on the face of the
pad opposite to the polishing plane. Alternatively, it may be
attached with a low-elastic modulus subpad, for example, of
polyurethane foam.
[0088] Typically to polish a work material by pressing its
polishing plane to a polishing pad and sliding the polishing pad
relatively to the work material, at least one of the work material
and the polishing table is moved. Polishing may be performed by
rotation or reciprocating motion of the holder, instead of rotation
of the polishing table. Other examples include polishing methods of
revolving polishing tables planetary and moving a belt-shaped
polishing pad linearly in the longitudinal direction, and the like.
The holder may be fixed, rotated, or moved reciprocally. The
polishing method is not particularly limited, if it can move the
polishing pad and the work material relatively to each other, but
should be selected properly according to the work material's
polishing plane and the polishing machine used.
[0089] The polishing condition is not particularly limited, and
preferably optimized according to the work material. For example,
the rotational velocity of the polishing table is preferably lower
at 200 rpm or less so that the work material will not be spun off,
and the pressure applied to the work material is preferably lower,
for example at about 50 kPa or less, when the work material's
polishing plane is copper, for prevention of generation of
scratches during polishing. In addition, the pressure is preferably
20 kPa or less when a work material having a low-dielectric
constant interlayer insulating film is used.
[0090] Polishing slurry is supplied continuously, for example, by a
pump between the polishing pad and the work material's polishing
plane during polishing. The feed rate is not limited, but the
surface of the polishing pad is preferably covered always with the
polishing slurry. The pad and the exposed organic fiber degenerated
by polishing are regenerated and preserved by dressing. The work
material after polishing is preferably washed thoroughly with
running water and dried after the water drops on the polishing
plane are removed, for example, by using a spin dryer.
[0091] Hereinafter, as an embodiment of the polishing method
according to the present invention, a polishing method when the
work material's polishing plane is a laminate film consisting of a
barrier conductor layer and additionally a metal layer such as of
copper that is formed on an insulation layer that has wiring and
trenches formed thereon will be described, along with the steps of
forming the wiring on semiconductor device.
[0092] For Example, the metal layer is a layer containing a metal
as the principal material such as a layer of a metal selected from
the group consisting of copper, copper alloys, copper oxide, and
copper alloy oxides (hereinafter, referred to as "copper and the
compounds thereof") or a metal such as tungsten, tungsten alloys,
silver, or gold; and a layer containing copper as the principal
component such as a layer of copper or the compound thereof is
preferable.
[0093] The barrier conductor layer (hereinafter, referred to as
"barrier layer") coated by the metal layer is preferably a barrier
layer against copper and the compounds thereof, in particular
against copper and copper alloys among the metals above. The
barrier layer is formed for prevention of diffusion of the metal
layer into the insulation film and improvement in adhesion between
the insulation film and the metal layer. Examples of the
compositions for the conductive layer include tantalum, titanium,
tungsten, the compounds thereof such as nitrides; oxides and
alloys, and the like.
[0094] Examples of the insulation films include interlayer
insulating films such as silicon film and organic polymer film.
Examples of the silicon films include silicon dioxide,
fluorosilicate glasses, organosilicate glasses obtained by using
trimethylsilane or dimethoxydiethylsilane as the starting material,
silicon oxynitride, silica-based films such as hydrogenated
silsesquioxane, silicon carbide, and silicon nitride. In addition,
examples of the organic polymer films include wholly aromatic
low-dielectric constant interlayer insulating films. In particular,
the interlayer insulating film preferably has a dielectric constant
of 2.7 or less.
[0095] First, an interlayer insulating film, for example, of
silicon dioxide is laminated on a silicon substrate. The interlayer
insulating film surface in then converted to an interlayer
insulating film having a surface irregularity by forming a certain
pattern by concave areas (substrate exposed areas) by any one of
known means such as resist layer formation or etching. A barrier
layer, for example, of tantalum is deposited, for example, by vapor
deposition or CVD along the surface irregularity on the interlayer
insulating film. Further, a metal layer, for example, of copper
covering the barrier layer is formed for example by vapor
deposition, plating, or CVD, filling the concave areas in the
barrier layer.
[0096] Then, the metal layer on the surface of substrate is
polished by CMP by using the polishing pad according to the present
invention while supplying polishing slurry (first polishing step).
Thus, the barrier layer of the convex area on the substrate is
exposed on the surface, giving a desired wiring pattern that still
retains the metal film in the concave areas. Part of the barrier
layer of the convex area may be polished together with the metal
layer during the polishing. In the second polishing step, at least
the exposed barrier layer and the metal layer in concave areas are
polished by CMP, by using a polishing slurry allowing polishing of
the metal, barrier and interlayer insulating layers. The polishing
is terminated when a desired pattern is obtained in which the
interlayer insulating film under the protruding barrier layer is
exposed entirely, the metal layer for wiring layer is left in the
concave areas, and the cross sectional area of the barrier layer is
exposed at the boundary of convex area and concave area. The
polishing pad according to the present invention is used at least
in the second polishing step, but preferably used also in the first
polishing step, as shown in this embodiment.
[0097] For ensuring the superiority in flatness after polishing, it
may be over-polished (e.g., if a desired pattern is obtained within
100 seconds in the second polishing step, polishing additionally
for 50 seconds in called 50% over-polishing) to a depth including
part of the interlayer insulating film of convex area.
[0098] The polishing pad and the polishing method using the same
according to the present invention can be applied, not only to
polishing of films containing mainly a metal such as Cu, Ta, TaN,
or Al filling the composite opening of the insulation layer
described above, but also to polishing of inorganic insulation
films such as silicon oxide film, glass, and silicon nitride formed
on a certain wiring board, films mainly containing polysilicon,
optical glasses such as photomask, lens, and prism, inorganic
conductive films such as ITO, end faces of optical Integrated
circuit, optical switching device, optical waveguide, and optical
fiber made of a glassy or crystalline material, optical single
crystals such as scintillator, single crystals for solid state
laser, sapphire substrates for blue laser LED, semiconductor single
crystals of SiC, GaP, GaAs, and the like, glass or aluminum
substrates for magnetism disk, magnetic head, and the like.
EXAMPLES
[0099] Hereinafter, the present invention will be described in
detail with reference to Examples, but it should be understood that
the present invention is not restricted by these Examples.
Example 1
[0100] An organic fiber poly-p-phenylene terephthalamide fiber
(trade name "Kevlar", manufactured by DuPont, fiber diameter: 12.5
.mu.m, fiber length: 3 mm) and a matrix composition, ABS resin
pellet, were melt-blended and tabletized in an extruding molding
machine. The content of the poly-p-phenylene terephthalamide fiber
was adjusted to 10 wt %. The tablet obtained was dried in a
large-sized dryer at 120.degree. C. for 5 hours, and then processed
into a sheet-shaped molding of 1.2 mm in thickness and 1 m in width
by using an extrusion-molding machine and a roll. Trenches having a
cross section in the rectangular shape having a depth of 0.6 mm and
a width of 2.0 mm were formed on the sheet in the grid pattern at a
pitch of 15 mm, and then, the sheet was cut into a circular form.
In addition, a double-sided adhesive tape was adhered to the face
opposite to the face whereon the trenches were formed, and it was
used as a polishing pad.
Example 2
[0101] A polishing pad was prepared in a similar manner to Example
1, except that a mixture of polyethylene, polypropylene, and
styrene elastomers at a ratio of 50:50:100 by weight is used as the
matrix composition.
Example 3
[0102] A polishing pad was prepared in a similar manner to Example
1, except that polypropylene was used as the matrix
composition.
Comparative Example 1
[0103] A polishing pad was prepared in A similar manner to Example
1, except that no organic fiber was used.
Comparative Example 2
[0104] A polyurethane foam polishing pad was prepared.
[0105] The pad was attached to the polishing table of a polishing
machine and surface-roughened by using a dresser with #160 diamond
whetstone for 30 minutes.
(Preparation of Polishing Slurry)
[0106] An abrasive-free polishing slurry (trade name: HS-C430
slurry, manufactured by Hitachi Chemical Co., Ltd.) and the same
polishing slurry with colloidal silica as the abrasive having an
average secondary particle diameter of 35 nm at a concentration of
0.37 wt % were used as polishing slurries for copper. Both
polishing slurries were blended with a hydrogen peroxide solution
at a rate, polishing slurry: hydrogen peroxide solution, of 7:3
when using.
(Polishing of Substrate)
[0107] By using the polishing pads prepared in Examples and
Comparative Examples and the polishing slurry prepared above,
silicon wafer substrates with and without wiring were polished as
follows, and the polishing speed, the polishing scratch, and the
dishing, an indicator of flatness, were determined.
[0108] The wafer was placed on a holder with an adhesive pad for
attaching wafer in a polishing machine. Each of the polishing pads
prepared in Examples and Comparative Examples was adhered to the
polishing table of the polishing machine and the holder having a
work material with its polishing plans facing downward was attached
on it in the polishing machine. The work material's polishing plane
was polished under an applied load of 4.times.10.sup.4 Pa, while
supplying the polishing slurry at a flow rate of 150 cc/min and
rotating the polishing table and the wafer at a frequency of 38
rpm; and the polishing was evaluated. Results are summarized in
Table 1.
(Evaluation of Polishing Speed)
[0109] A silicon wafer substrate (diameter: 13 cm) having a silicon
dioxide film layer without wiring on which a copper film of 1 .mu.m
in thickness as formed was polished for 2 minutes. The thicknesses
of the copper film before and after polishing were determined by
measuring the sheet resistivity by using a resistivity meter RT-7
manufactured by Napson Corporation and calculating the film
thickness from the resistivity, and the difference between the film
thicknesses before and after CMP was calculated. Results are
summarized in Table 1.
(Evaluation of Polishing Scratch)
[0110] The number of the scratches on the wafer used for evaluation
of polishing speed was counted by visual observation. Results are
also summarized In Table 1.
[0111] .largecircle.: Less than five scratches on the work
material's polishing plane after polishing
[0112] X: Five or more scratches on the work material's polishing
plane after polishing
(Dishing Amount)
[0113] A silicon substrate (diameter: 13 cm) having a surface shape
in the striped pattern consisting of wiring metal (copper) areas of
100 .mu.m in width and insulation film (silicon dioxide) areas of
100 .mu.m in width that are formed alternately was prepared as a
work material, by forming a silicon dioxide film having a thickness
of 300 nm on a silicon wafer, forming trenches having a depth of
0.5 .mu.m on the silicon dioxide film at a wiring density of 50%,
forming a tantalum nitride film having a thickness of 50 nm as a
barrier layer by a known sputtering method, and forming a copper
film of 1.0 .mu.m thickness similarly by sputtering and embedding
it by a known heat treatment.
[0114] The work material was subjected to two-step polishing,
polishing of copper film and of barrier layer, and the decrease in
the amount of film in wiring metal area from that in the insulation
film area was determined from the surface shape in the
stripe-patterned area, as determined by using a stylus profilometer
(Dektat3030, manufactured by Veeco/Sloan). Results are also
summarized in Table 1. "No measurement possible" in the Table,
means that the substrate could not be polished at low polishing
speed or that there were too many polishing scratches prohibiting
measurement.
[0115] Polishing pads prepared in Example 1 and Comparative Example
1 have the same matrix resin and differ from each other in whether
the substrate contains fiber. The polishing pad of Example 1
according to the present invention is resistant to generation of
scratches and thus superior to the pad of Comparative Example 1
containing no organic fiber. The pad of Comparative Example 1
resulted in a greater number of polishing scratches, which
prohibited dishing measurement. In the Example, use of an
abrasive-free polishing slurry almost prohibited polishing, and
thus, the polishing mechanism in the Example is obviously different
from that in Comparative Example 1 or 2, which is higher in
polishing speed. TABLE-US-00001 TABLE 1 Polishing speed Dishing Pad
Polishing slurry (.ANG./min) Scratches (.ANG.) Example 1
Abrasive-free 50 .largecircle. No measurement polishing slurry
possible Abrasive- 1000 .largecircle. 300 containing polishing
slurry Example 2 Abrasive-free 70 .largecircle. No measurement
polishing slurry possible Abrasive- 1000 .largecircle. 300
containing polishing slurry Example 3 Abrasive-free 40
.largecircle. No measurement polishing slurry possible Abrasive-
800 .largecircle. 300 containing polishing slurry Comparative
Abrasive-free 1000 X No measurement Example 1 polishing slurry
possible Abrasive- 1500 X No measurement containing possible
polishing slurry Comparative Abrasive-free 2200 .largecircle. 500
Example 2 polishing slurry Abrasive- 2500 .largecircle. 1100
containing polishing slurry
[0116] Then, a polishing test was performed in a similar manner to
above, except that an abrasive-containing polishing slurry, which
was higher in polishing speed from the results above, was used and
a processing load of 2.times.10.sup.4 Pa was applied. Results are
summarized in Table 2. As apparent from Table 2, there was almost
no difference between the polishing speeds in Examples and those
under the polishing conditions above, indicating that it was
possible to polish even under a low load, i.e., under a low
friction force. On the other hand in Comparative Examples, the
polishing speed decreased drastically under low load, for example,
under this condition. TABLE-US-00002 TABLE 2 Polishing speed
Dishing Pad (.ANG./min) Scratches (.ANG.) Example1 700
.largecircle. 300 Example2 700 .largecircle. 300 Example3 700
.largecircle. 300 Comparative 400 X No measurement Example 1
possible Comparative 100 .largecircle. 600 Example 2
[0117] The results above indicate that use of the polishing pad
according to the present invention allows improvement in flatness
while reducing the load applied to the insulation layer during
CMP.
[0118] Hereinafter, the polishing-pad according to the present
invention suitable for use in the polishing step of irradiating
light via a polishing pad onto the semiconductor wafer surface,
detecting the change in the reflectance, and managing the polishing
end point will be described with reference to Examples, but the
present invention is not limited to these Examples.
[0119] For preparation of polishing pads, prepared were the
following plate materials 1 to 3.
[Plate Material 1]
[0120] An organic fiber, poly-p-phenylene terephthalamide fiber
("Kevlar", manufactured by DuPont, fiber diameter; 12.5 .mu.m,
fiber length: 3 mm), and a matrix resin, AS resin pellet (trade
name: Litac A-100PC, manufactured by Nippon A&L Inc.), were
melt-blended in an extruding molding machine and then tabletized.
The poly-p-phenylene terephthalamide fiber was adjusted to a
content of 5 wt %. This tablet was dried in a large-sized dryer at
120.degree. C. for 5 hours, and a sheet-shaped molding of 1.2 mm in
thickness and 1 m in width was prepared by using an
extrusion-molding machine and a roll.
[Plate Material 2]
[0121] The AS resin pellet (ditto) was melt-blended in an extruding
molding machine and tabletized. The tablet was dried in a
large-sized dryer at 120.degree. C. for 5 hours, and a sheet-shaped
molding of 1.2 mm in thickness and 1 m in width was prepared by
using an extrusion-molding machine and a roll. The plate material
contains no organic fiber.
[Plate Material 3]
[0122] A chopped para-aramide fiber ("Kevlar", manufactured by
DuPont, fiber diameter: 12.5 .mu.m, fiber length: 5 mm), a
para-aramide fiber pulp ("Kevlar", manufactured by DuPont, fiber
diameter; 1 .mu.m, fiber length: 1 mm), and a chopped meta-aramide
fiber ("Conex", manufactured by Teijin Ltd., fiber diameter: 25
.mu.m, fiber length: 6 mm, softening temperature: 280.degree. C.)
were blended: an aqueous solution of 20 wt % of water-soluble epoxy
resin binder (trade name: "V Coat", manufactured by Dainippon In
and Chemicals, Inc., glass transition temperature: 110.degree. C.)
was sprayed thereon and the mixture was dried by heating
(150.degree. C., 3 min); and the mixture was heat-compressed
between a pair of heated rolls (temperature: 300.degree. C., linear
pressure: 196 kN/m), to give a nonwoven fabric wherein the chopped
meta-aramide fiber was fused thermally to the chopped para-aramide
fiber. The basis weight was 70 g/m.sup.2, and the ratio of chopped
para-aramide fiber/para-aramide fiber pulp/chopped meta-aramide
fiber/epoxy resin binder was 58/17/8/17 by weight.
[0123] A varnish containing bisphenol A epoxy resin (trade name:
"EP-828SK", manufactured by Yuka Shell Epoxy K.K.), a curing agent
dicyandiamide and an accelerator 2-ethyl-4-methylimidazole was
prepared. For preparation of the varnish, 20 parts by weight of the
curing agent, 0.1 parts by weight of the accelerator, and 40 parts
by weight of a solvent methylethylketone were used with respect to
100 parts by weight of the bisphenol A epoxy resin.
[0124] The aramide fiber nonwoven fabric described above was
impregnated with the varnish, and the mixture was dried under heat
(170.degree. C., 5 min), to give a prepreg. The amount of the resin
added was adjusted in such a manner that the prepreg after molding
with heating and pressure had a thickness of 0.08 mm. The content
of the aramide fiber nonwoven fabric was 60 wt %.
[0125] A laminated plate having a thickness of 1.0 mm was obtained
by piling twelve prepreg layers together with two release films
(polypropylene film of 50 .mu.m in thickness) at both ends, holding
the pile between two mirror-surfaced stainless steel plates,
placing multiple sets thereof in a hot press via two thickness
cushion material of 10 mm in thickness made of multiple Kraft paper
layers, and molding them with heating and pressure (temperature:
170.degree. C., pressure: 300 kPa, period: 120 min).
Example 3
[0126] The plate material 1 was cut into a circular disc of
.phi.500 mm: trenches are formed on the surface thereof so that a
polishing slurry supplied during polishing flows under the jig
holding the wafer to below the wafer (in a grid pattern, trench
width: 2 mm, trench pitch; 15 mm, trench depth: 0.6 mm); and a
double-aided adhesive tape was adhered to the opposite face, to
give a polishing pad.
Example 4
[0127] The plate material 1 was cut into rectangular disk-shaped
small pieces of 56 mm in length and 19 mm in width with rounded
edges (curvature radius: 1.0 mm). Then, the plate material 3 was
cut into a circular disc of .phi.500 mm in a similar manner to
Example 3, and trenches were formed on the surface thereof. A hole
in the rectangular disk shape of 56 mm in length and 19 mm in width
with rounded edges similar to the edges described above was formed
at a position halfway from the center of the circular disc to the
circumference in the radial direction, in the manner that the
longitudinal direction of the hole represents the radial direction.
The small piece in the rectangular disk shape described above of
plate material 1 was inserted to the circular disc hole an a window
for transmitting light for optical detection. Finally, a
double-sided adhesive tape was adhered to the face opposite to the
face where the trenches were formed, to give a polishing pad.
Traditional Example 1
[0128] A commercially available polishing pad of a polyurethane
foam resin, having a light transmission window of a transparent
resin plate for optical detection in a rectangular disk shape of 56
mm in length and 19 mm in width with rounded edges, was made
available. ("IC-1000/Suba-4000 prepared by Rodel Inc., thickness:
1.2 mm)
Comparative Example 3
[0129] A polishing pad was prepared by processing the plate
material 2 in a similar manner to Example 3.
Reference Example 1
[0130] A polishing pad was prepared by processing the plate
material in a similar manner to Example 3. The polishing pad does
not have a window, different from that in Example 4.
[0131] The light transmittance of the polishing pads obtained in
the Examples, the Traditional Example, the Reference Example and
the Comparative Example was determined. The measurement was
performed at the window if the polishing pad has a light
transmission window, and at the plate material of the polishing pad
if not. The light transmittance was determined at a measurement
wavelength of 670 nm by using a spectrophotometer UV-2200
manufactured by Shimadzu Corp. The measured value was converted to
a transmittance of a plate of 1 mm in thickness, by using
Lambert-Beer's law.
[0132] The polishing machine used was MIRRA manufactured by Applied
Materials U.S. and each of the polishing pads was adhered and fixed
to its polishing table of .phi.500 mm. As for polishing pads having
a light transmission window for optical detection, the window of
the polishing pad was adjusted to the window of the polishing table
of polishing machine. Each polishing pad after adhered to the
polishing table, was subjected to dressing at 9LB for 15 minutes,
as a diamond dresser manufactured by Asahi Diamond Industrial Co.,
Ltd. (whetstone: #170, acryl coated) is fit to the pad conditioner
mechanism in the polishing machine. Observation of the surface
state of each polishing pad revealed that the fiber in exposed on
the surface of the polishing pads of Example 3 and Reference
Example 1 (exposure length: approximately 500 .mu.m). The fiber was
exposed (exposure length: approximately 500 .mu.m) similarly on the
window as well as on the entire surface of the polishing pad of
Example 4. Exposure of the fiber was not observed on the polishing
pads of Traditional Example 1 and Comparative Example 3.
[0133] The structure, the surface state and the light transmittance
of the polishing pads of the Examples, the Traditional Example, the
Reference Example and the Comparative Example are summarized in
Table 3. TABLE-US-00003 TABLE 3 Light transmittance Surface
Structure Window (%) state Example 3 AS resin plate not have 49.1
Fiber with aramide exposure fiber Example 4 epoxy resin have 49.1
Fiber plate with (Plate exposure aramide fiber material 1)
Traditional polyurethane have 67.2 No fiber Example 1 foam exposure
resin plate (two-layers structure) Comparative AS resin plate not
have 94.5 No fiber Example 3 exposure Reference epoxy resin not
have 3.6 Fiber Example 1 plate with exposure aramide fiber
[0134] Silicon wafers (insulation film blanket wafer and TEG wafer)
were polished as follows by each of the polishing pads of the
Examples, Traditional Example, Reference Example and Comparative
Example placed in a polishing machine as described above, and the
CMP polishing slurry, and the characteristics were evaluated from
the following viewpoints. The evaluation results are summarized In
Table 4.
(Evaluation of the Number of Polishing Scratches)
[0135] A blanket wafer having a silicon oxide film of 1 .mu.m in
thickness formed on a .phi.200 mm silicon wafer by the TEOS-plasma
CVD method was placed in a polishing machine. Then, the wafer is
held by the head-unit and the silicon oxide film side was brought
into contact with the polishing pad on the polishing table. The
silicon oxide film on wafer was polished for 1 minute under a
polishing pressure applied on the wafer surface during polishing
set to 21 kPa (3 PSI) while supplying a mixture of a cerium
oxide-based polishing slurry (HS-8005, manufactured by Hitachi
Chemical Co., Ltd.) at a feed rate 40 mL/min and an additive
(HS-8102GP, manufactured by Hitachi Chemical Co., Ltd.) at a feed
rate of 160 mL/min by dropping onto the polishing table and
rotating the polishing table at 100 rpm and the head at 90 rpm. The
silicon wafer after polishing was washed thoroughly with purified
water and dried, and then, the entire surface of the wafer was
observed in dark field under a microscope and the number of the
polishing scratches was counted.
(Evaluation of Polishing Speed)
[0136] The thickness of the silicon oxide film on each blanket
wafer after evaluation of the number of polishing scratches was
determined by using a light-interference thickness analyzer, and an
average polishing speed was determined from the difference from the
thickness of silicon oxide film determined before polishing.
(Evaluation of Uniformity)
[0137] The polishing speeds of the silicon oxide film at 45 point
at an interval of 8 mm from the position at 5 mm separated from
terminal on two diameters orthogonal to each other on each blanket
wafer face were determined in a similar manner to the measurement
of polishing speed, and the variations (1.delta./average polishing
speed.times.100) in polishing speed was calculated from the
standard deviation (1.delta.).
(Evaluation of Possibility of End Point Management)
[0138] A pattern of lines having a width and a pitch respectively
of 25 to 2,000 .mu.m was formed with a silicon nitride film having
a thickness of 100 nm on a .phi.200 mm silicon wafer; the Si
exposed area was etched to a depth of 350 nm; and a silicon oxide
film was formed on the wafer by the TEOS-plasma CVD method to a
thickness of 600 nm, to give a TEG wafer having an irregularity of
450 nm on the surface. While polishing the wafer under the Dame
condition as the blanket wafer described above, it was judged
whether it is possible to detect exposure of the silicon nitride
film, by using the ISRM laser-beam end point-managing system
attached to the polishing machine (MIRRA, manufactured by Applied
Material Technologies) used for evaluation.
(Evaluation of Flatness)
[0139] After polishing and detecting the exposure of silicon
nitride film by the end point management system described above,
the difference in surface level between the line (width 100 .mu.m)
of the silicon nitride film on the TEG wafer after and the line of
the neighboring silicon oxide film (width 300 .mu.m) was determined
by using a stylus profilometer Dektak3030 (manufactured by SLOAN).
TABLE-US-00004 TABLE 4 Polishing Uni- Scratch speed formity
(number/ End point Flatness (nm/min) (%) wafer) management (mm)
Example 3 280 3 3 possible 20 Example 4 290 5 5 possible 25
Traditional 180 5 30 possible 20 Example 1 Comparative 210 12 55
possible 20 Example 3 Reference 310 5 5 Not -- Example 1
possible
[0140] The results of examples 3 and 4 in Table 4 show that use of
the polishing pad according to the invention allows management of
the end point by optical detection, and comparison with the results
in Traditional Example 1 and Comparative Example 3 shows that it is
possible to suppress generation of polishing scratches by the
action of the organic fiber. It was also confirmed that the
polishing speed was higher and the uniformity was also sufficiently
high. The polishing pad of Reference Example 1 did not show a
sufficiently distinctive change in reflectance for allowing
detection of the end point by light irradiation during polishing of
the TEG wafer evaluated. It corresponds to the fact that the
polishing pad of Reference Example 1 showed low light transmittance
in the earlier experiment.
[0141] Hereinafter, Examples concerning the maximum exposure fiber
length will be given.
Example 5
[0142] A nonwoven fabric having a basis weight of 70 g/m.sup.2
("EPM-4070TE", manufactured by Japan Vilene Co., Ltd.) made of a
polyester fiber having a fiber diameter of 12.5 .mu.m and a fiber
length of 5 mm was impregnated with the following varnish, and the
mixture was dried at 170.degree. C. for 5 minutes, to give a
prepreg.
[0143] The varnish was prepared by adding 20 parts by weight of a
curing agent dicyandiamide and 0.1 parts by weight of an
accelerator 2-ethyl-4-methylimidazole to 100 parts by weight of a
bisphenol A epoxy resin and dissolving the mixture in 40 parts by
weight of methylethylketone.
[0144] Twenty prepregs were piled between a pair of release films
(polypropylene, thickness; 50 .mu.m), and the pile was held between
a pair of mirror-surface plates. It was molded via two cushion
papers having a thickness of 10 mm in a hot press with heating and
pressure. The molding condition was 175.degree. C. and 400 kPa for
120 minutes. As a result, a laminated plate having a thickness 1.5
mm was obtained. The fiber content in the entire laminated plate
was 50 wt %. The plate was cut into a circular form; the surface
was roughened by using #70 diamond whetstone; and then trenches are
formed thereon, to give a polishing pad. Trenches of 2 nm in width
and 0.6 mm in depth were formed in a grid pattern with a pitch of
15 mm.
Example 6
[0145] A laminated plate of 1.5 mm in thickness was prepared in a
similar manner to Example 5, except that ten prepregs shown in
Example 5 and ten non-resin-impregnated by polyester nonwoven
fabrics were laminated alternately. The fiber content in the entire
laminated plate was 70 wt %. Then, the surface was roughened and
trenches are formed in a similar manner to Example 5, to give a
polishing pad.
Example 7
[0146] A polishing pad was prepared in a similar manner to Example
5, except that a polyester woven fabric having a basis weight of
130 g/m.sup.3 ("BKE poplin", manufactured by Asahi Kasei Corp.,
fiber diameter: 9 .mu.m) was used as the fiber. In this Example,
the fiber content in the entire laminated plate was 50 wt %.
Example 8
[0147] An organic fiber, polyester fiber having a diameter of 12.5
.mu.m and a length of 3 mm (manufactured by Japan Vilene Co.,
Ltd.), and a matrix resin, ABS resin pellet, were melt blended in
an extruding molding machine and tabletized. The fiber content
therein was adjusted to 10 wt %. The tablet was dried in a
large-sized dryer at 120.degree. C. for 5 hours, and was converted
by using an extrusion-molding machine and a roll into a
sheet-shaped molding having a thickness of 1.2 mm and a width of 1
m. Trenches having a rectangular cross section of 0.6 mm in depth
and 2.0 mm in width were formed thereon in a grid pattern with a
pitch of 15 mm, and the molding was out into a circular plate.
Then, a double-Bided adhesive tape was adhered to the face opposite
to the face whereon the trenches are formed, and then, the surface
was roughened by using #70 diamond whetstone, to give a polishing
pad.
Reference Example 2
[0148] A polishing pad was prepared in a similar manner to Example
5, except that a nonwoven fabric having a basis weight of 70
g/m.sup.2 was prepared by spraying an aqueous 20 wt % solution of a
water-soluble epoxy resin binder (trade name: "V Coat",
manufactured by Dainippon Ink and Chemicals, Inc.) on a blend of a
chopped para-aramide fiber (Technola", manufactured by Teijin Ltd.,
fiber diameter: 12.5 .mu.m, fiber length: 5 mm) and a chopped
meta-para-aramide fiber ("Conex", manufactured by Teijin Ltd.,
fiber diameter: 25 .mu.m, fiber length: 6 mm) and drying the
mixture at 150.degree. C. for 3 minutes under heat, and the
nonwoven fabric was heat compressed between heat rolls at
300.degree. C., under an applied linear pressure of 196 kN/m. In
addition, the surface was roughened by using #150 diamond
whetstone. In the Reference Example, the fiber content in the
entire laminated plate was 50 wt %.
Comparative Example 4
[0149] An ABS (acrylonitrile-butadiene rubber-styrene copolymer)
plate having a thickness of 1.5 mm was cut into a circular form,
and trenches of 2 mm in width and 0.6 mm in depth were formed on
the surface in a grid pattern with a pitch of 15 mm. Then, the
surface was roughened by using #70 diamond whetstone to give a
polishing pad.
Reference Example 3
[0150] A polishing pad was prepared in a similar manner to Example
8, except that the surface was roughened by using #70 diamond
whetstone.
(Observation of Surface)
[0151] The pad surface at any five points was observed under an SEM
(scanning electron microscope) at magnifications of 100 and 200
times, and the maximum length of exposed fiber was determined.
(Polishing Slurry)
[0152] A CMP slurry was prepared as the polishing slurry by the
following method:
[0153] Two kg of cerium carbonate hydrate was place in a platinum
container and sintered at 800.degree. C. for 2 hours in air, and 1
kg of the cerium oxide powder thus obtained was pulverized in a jet
mill while it is dry. Twenty-three grams of an aqueous ammonium
polyacrylate salt solution (40 wt %) and 8,977 g of deionized water
were added thereto, and the mixture was ultrasonicated for 10
minutes while agitated. The slurry obtained was filtered through a
1-micron filter, and deionized water was added thereto, to give a 5
wt % slurry. The pH of the slurry was 8.3. After dilution to a
suitable concentration, the slurry particles were analyzed by using
a laser diffraction particle size distribution analyzer, and as a
result, D99% of particle diameter was 0.99 .mu.m.
(Polishing Method and Evaluation of Polishing Characteristics)
[0154] Prepared were a blanket wafer having a silicon oxide film of
2 .mu.m in thickness formed on a .phi.127 mm silicon wafer by the
TEOS-plasma CVD method, and a test wafer carrying trenches having a
square convex area formed on a .phi.200 mm Si substrate and
additionally a Si.sub.3N.sub.4 film and a silicon oxide film having
a thickness of 600 .mu.m formed by the TEOS-plasma CVD method
thereon. The trench had a depth of 0.35 .mu.m; the region where the
density of the convex area was 60%, and the trench width is 500
.mu.m was used.
[0155] The wafer was placed on the holder of polishing machine with
the adhesive pad for attaching to a wafer substrate; the polishing
pad prepared was adhered to the .phi.380 mm polishing table; the
holder was placed on the polishing table with the insulation film
side facing downward; and the processing load was set to 29 kPa
(300 gf/cm.sup.2). The insulation film was polished by rotating the
polishing table and the wafer at 38 rpm for 2 minutes while
supplying the cerium oxide polishing slurry at a rate of 150 cc/min
by dropping on the polishing table. The wafer after polishing was
washed thoroughly with purified water and then dried. The
difference between the film thicknesses before and after polishing
was measured by using a light-interference film thickness analyzer
and the polishing speed was calculated. As for polishing scratch,
the wafer surface after polishing was observed in dark field under
a microscope and the number of the scratches remaining on the wafer
surface due to polishing was counted.
[0156] Alternatively as for evaluation of flatness, the wafer was
polished to a depth equivalent to the difference, 1 .mu.m, in the
levels of the convex area and concave area on TEG wafer, and the
final difference in level before exposure of the convex area
Si.sub.3N.sub.4 film was determined. The dishing in the trench area
on the TEG wafer was determined by using a stylus profilometer.
[0157] Table 5 shows the polishing characteristics obtained in the
Examples. Reference Example and Comparative Example. In Examples 5,
6, 7 and 8 where the polishing pad contains the polyester fiber
according to the invention was used, it is possible to reduce the
length of the exposed fiber easily and the polishing pad is
superior in flatness and the wafer surf ace has fewer polishing
scratches, compared to in Reference Example 2 wherein the pad
contains a high-rigidity aramide fiber. In addition, an apparent
from comparison between Examples 5, 6, 7 and 8 and Comparative
Example 4 containing no fiber, the polishing speed was improved and
the polishing scratches were fewer as well. TABLE-US-00005 TABLE 5
Maximum exposure fiber Polishing Scratch length speed (number/
Dishing (.mu.m) (nm/min) wafer) Flatness (nm) Example5 10 210 0 20
25 Example6 10 240 0 20 28 Example7 10 240 0 20 29 Example8 10 220
10 30 25 Reference 50 190 40 20 40 Example 2 Comparative 0 10 250
No No Example 4 measure- measure- ment ment possible possible
Reference 150 350 0 50 50 Example 3
[0158] An apparent from Table 5, it is possible to improve the
flatness and the dishing-resistivity in the trench area without
generating polishing scratches by using a polishing pad having a
maximum exposure fiber length of 0.1 mm or less and to streamline
semiconductor forming processes including flattening of interlayer
insulating film, BPSG film, and production of shallow trench
isolation formation.
INDUSTRIAL APPLICABILITY
[0159] If CMP is performed by using the polishing pad according to
the present invention or the polishing pad-prepared by the
production method according to the present invention, it in
possible to suppress generation of minute polishing scratch on the
work material, because of the organic fiber exposed on the work
material-side surface of the polishing pad. Thus, it is possible to
polish in superior flatness at low load. In addition, it is also
possible to manage the polishing end point of the work material
while suppressing generation of polishing scratches by using an
optical detection system monitoring the polishing state of work
material. These effects in combination enable improvement in the
productivity and the yield of the polished work material.
[0160] Thus, for example, it is possible to polish substrates under
a smaller load on the interlayer insulating film and give products
superior in flatness in semiconductor device manufacturing
processes and thus, the polishing pad according to the invention
may be used easily in the next-generation dual damascene
method.
* * * * *