U.S. patent application number 14/344988 was filed with the patent office on 2014-12-25 for polishing pad.
This patent application is currently assigned to TORAY INDUSTRIES, INC.. The applicant listed for this patent is Seiji Fukuda, Yohei Noro, Ryoji Okuda. Invention is credited to Seiji Fukuda, Yohei Noro, Ryoji Okuda.
Application Number | 20140378035 14/344988 |
Document ID | / |
Family ID | 47883398 |
Filed Date | 2014-12-25 |
United States Patent
Application |
20140378035 |
Kind Code |
A1 |
Noro; Yohei ; et
al. |
December 25, 2014 |
POLISHING PAD
Abstract
A polishing pad for chemical mechanical polishing includes at
least a polishing layer whose polishing surface includes a first
groove and a second groove, the first and second grooves have side
surfaces, which are continuous with the polishing surface, on each
edge in a groove width direction, the first groove has an angle of
larger than 105 degrees and 150 degrees or smaller, which is formed
between the polishing surface and the side surface continuous with
the polishing surface, on at least one edge in the groove width
direction, and the second groove has an angle of 60 degrees or
larger and 105 degrees or smaller, which is formed between the
polishing surface and the side surface continuous with the
polishing surface, on both of two edges in the groove width
direction.
Inventors: |
Noro; Yohei; (Otsu-shi,
JP) ; Okuda; Ryoji; (Otsu-shi, JP) ; Fukuda;
Seiji; (Otsu-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Noro; Yohei
Okuda; Ryoji
Fukuda; Seiji |
Otsu-shi
Otsu-shi
Otsu-shi |
|
JP
JP
JP |
|
|
Assignee: |
TORAY INDUSTRIES, INC.
Tokyo
JP
|
Family ID: |
47883398 |
Appl. No.: |
14/344988 |
Filed: |
September 13, 2012 |
PCT Filed: |
September 13, 2012 |
PCT NO: |
PCT/JP2012/073538 |
371 Date: |
March 14, 2014 |
Current U.S.
Class: |
451/528 |
Current CPC
Class: |
B24B 37/26 20130101 |
Class at
Publication: |
451/528 |
International
Class: |
B24B 37/26 20060101
B24B037/26 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2011 |
JP |
2011-201350 |
Claims
1. A polishing pad for chemical mechanical polishing, the polishing
pad comprising at least a polishing layer, wherein a polishing
surface of the polishing layer includes a first groove and a second
groove, the first and second grooves have side surfaces, which are
continuous with the polishing surface, on each edge in a groove
width direction, the first groove has an angle of larger than 105
degrees and 150 degrees or smaller, which is formed between the
polishing surface and the side surface continuous with the
polishing surface, on at least one edge in the groove width
direction, and the second groove has an angle of 60 degrees or
larger and 105 degrees or smaller, which is formed between the
polishing surface and the side surface continuous with the
polishing surface, on both of two edges in the groove width
direction.
2. The polishing pad according to claim 1, wherein the second
groove has a bottom face.
3. The polishing pad according to claim 2, wherein a groove-area
ratio per unitary unit is 5% or higher and 50% or lower, and an
area occupying ratio of the first groove per groove area is 30% or
higher and 90% or lower.
4. The polishing pad according to claim 1, wherein the first and
second grooves are formed in a lattice shape.
5. The polishing pad according to claim 4, wherein the sum total of
groove lengths of the first grooves formed on the polishing surface
is 10% or higher and 90% or lower of the sum total of groove
lengths of grooves formed on the polishing surface.
6. The polishing pad according to claim 4, wherein the polishing
surface is circular, and the first groove formed on the polishing
surface is formed in an area where two straight lines passing
through the center of the polishing surface and intersected with
each other are included and a distance from at least one of two
straight lines is 70% or lower of the radius of the polishing
surface.
7. The polishing pad according to claim 4, wherein the first groove
has an angle of larger than 105 degrees and 150 degrees or smaller,
which is formed between the polishing surface and the side surface
continuous with the polishing surface, on both of two edges in the
groove width direction.
Description
FIELD
[0001] The present invention relates to a polishing pad. More
specifically, the invention relates to a polishing pad which is
preferably used to form a planar surface on semiconductors,
dielectric material/metal composites, integrated circuits, and the
like.
BACKGROUND
[0002] As the density of semiconductor devices increases, the
importance of technologies for forming multilayer wires, interlayer
insulating films in association therewith, and electrodes, such as
plugs and damascene electrodes, has been increasing. Together with
this, the importance of a planarization process for these
interlayer insulating films and metal films of the electrodes has
been also increasing. As an efficient technology for this
planarization process, a polishing technology, which is referred to
as chemical mechanical polishing (CMP), has been widely used.
[0003] In general, a CMP apparatus is configured to include a
polishing head which holds a semiconductor wafer that is a material
to be treated, a polishing pad for carrying out a polishing
treatment of the material to be treated, and a polishing platen
which holds the polishing pad. Further, the polishing technology,
which is referred to as CMP, is a technology in which polishing is
performed on a material to be polished using a polishing pad having
a polishing layer while supplying slurry. Specifically, the CMP
technology of the semiconductor wafer is to planarize a surface
layer of the wafer in such a manner that projecting portions on the
surface layer of the wafer are removed by causing the semiconductor
wafer (hereinafter, simply referred to as the wafer) and the
polishing pad to perform relative motion using slurry.
[0004] There are required properties for the CMP technology, such
as securement of local planarity and global planarity of a wafer,
prevention of defects, and securement of a high polishing rate.
Therefore, in order to attain these required properties, the
configuration of grooves of the polishing pad (pattern of grooves,
cross-section of grooves, and the like), which is one of major
factors affecting polishing characteristics, is devised in various
ways.
[0005] For example, a technology for stabilizing polishing
characteristics has been known in which a cross-section of grooves
formed on a surface of a polishing layer is V-shaped or U-shaped,
and the grooves are formed in a spiral pattern or a stitch pattern
(see Patent Literature 1).
[0006] In such a technology, there is a case where scratches are
generated on the surface of the wafer due to a corner portion of
the cross-section of grooves or a case where a burr-like object is
formed on the corner portion of the cross-section due to dressing
or the like performed before and after polishing or during
polishing and thus scratches are generated. As a technology to
solve these problems, a technology has been also known in which an
inclined face is provided on a boundary portion between the
polishing surface and the groove (see Patent Literatures 2 and
3).
CITATION LIST
Patent Literature
[0007] Patent Literature 1: Japanese Laid-open Patent Publication
No. 2001-212752 [0008] Patent Literature 2: Japanese Laid-open
Patent Publication No. 2010-45306
SUMMARY
Technical Problem
[0009] To address this circumstance, the present inventors found
that when an inclined face with a specific angle is provided on the
boundary portion between the polishing surface and the groove, a
suction force acts between the wafer and the polishing pad and thus
a polishing rate becomes high and in-plane uniformity becomes
excellent. Since it is important to provide the inclined face on
the boundary portion between the polishing surface and the groove,
for example, a case where the cross-section of the groove is
V-shaped is also applicable. Incidentally, in consideration of a
manufacturing process, it is preferable in that the cross-section
of the groove has a simple shape.
[0010] However, in a case where the cross-section of the groove is
V-shaped, the inventors found that there is a problem in that
polishing defects are increased caused by a fact that functions of
supplying and discharging slurry are not performed sufficiently at
a final period of lifetime of the polishing pad when the polishing
pad is worn in accordance with the use of the polishing pad and a
cross-sectional area of the groove is decreased.
[0011] The invention is contrived in view of such problems of the
related art, and an object thereof is to provide a polishing pad
without increase in polishing defects caused by deterioration of
the functions of supplying and discharging slurry even when the
polishing pad is worn in accordance with the use of the polishing
pad, while having a high polishing rate and an excellent in-plane
uniformity.
Solution to Problem
[0012] The inventors considered that the above-described problems
may be solved by combining a groove (for example, a V-shaped
groove) for a high polishing rate and an excellent in-plane
uniformity which has an inclined face with a specific angle formed
on the boundary portion between the polishing surface and the
groove, and a groove (for example, an I-shaped groove or a
trapezoid (substantially I-shaped) groove) for maintaining the
functions of supplying and discharging of slurry even when the
polishing pad is worn in accordance with the use of the polishing
pad.
[0013] In order to solve the problems described above, the
invention employs a means such as follows.
[0014] That is, a polishing pad for chemical mechanical polishing
includes at least a polishing layer, wherein a polishing surface of
the polishing layer includes a first groove and a second groove,
the first and second grooves have side surfaces, which are
continuous with the polishing surface, on each edge in a groove
width direction, the first groove has an angle of larger than 105
degrees and 150 degrees or smaller, which is formed between the
polishing surface and the side surface continuous with the
polishing surface, on at least one edge in the groove width
direction, and the second groove has an angle of 60 degrees or
larger and 105 degrees or smaller, which is formed between the
polishing surface and the side surface continuous with the
polishing surface, on both of two edges in the groove width
direction.
Advantageous Effects of Invention
[0015] According to the invention, it is possible to provide a
polishing pad without increase in polishing defects even when the
polishing pad is worn in accordance with the use of the polishing
pad and functions of supplying and discharging slurry are
deteriorated, while having a high polishing rate and an excellent
in-plane uniformity.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1A is a diagram illustrating a cross-section of a first
groove (first example) which a polishing pad according to an
embodiment of the invention has.
[0017] FIG. 1B is a diagram illustrating a cross-section of the
first groove (second example) which the polishing pad according to
the embodiment of the invention has.
[0018] FIG. 10 is a diagram illustrating a cross-section of the
first groove (third example) which the polishing pad according to
the embodiment of the invention has.
[0019] FIG. 1D is a diagram illustrating a cross-section of the
first groove (fourth example) which the polishing pad according to
the embodiment of the invention has.
[0020] FIG. 2A is a diagram illustrating a cross-section of a
second groove (first example) which the polishing pad according to
the embodiment of the invention has.
[0021] FIG. 2B is a diagram illustrating a cross-section of the
second groove (second example) which the polishing pad according to
the embodiment of the invention has.
[0022] FIG. 2C is a diagram illustrating a cross-section of the
second groove (third example) which the polishing pad according to
the embodiment of the invention has.
[0023] FIG. 2D is a diagram illustrating a cross-section of the
second groove (fourth example) which the polishing pad according to
the embodiment of the invention has.
[0024] FIG. 2E is a diagram illustrating a cross-section of the
second groove (fifth example) which the polishing pad according to
the embodiment of the invention has.
[0025] FIG. 2F is a diagram illustrating a cross-section of the
second groove (sixth example) which the polishing pad according to
the embodiment of the invention has.
[0026] FIG. 3A is a cross-sectional view illustrating a
configuration example (first example) of a unitary unit including
the first and second grooves.
[0027] FIG. 3B is a cross-sectional view illustrating a
configuration example (second example) of a unitary unit including
the first and second grooves.
[0028] FIG. 3C is a cross-sectional view illustrating a
configuration example (third example) of a unitary unit including
the first and second grooves.
[0029] FIG. 3D is a cross-sectional view illustrating a
configuration example (fourth example) of a unitary unit including
the first and second grooves.
[0030] FIG. 3E is a cross-sectional view illustrating a
configuration example (fifth example) of a unitary unit including
the first and second grooves.
[0031] FIG. 3F is a cross-sectional view illustrating a
configuration example (sixth example) of a unitary unit including
the first and second grooves.
[0032] FIG. 3G is a cross-sectional view illustrating a
configuration example (seventh example) of a unitary unit including
the first and second grooves.
[0033] FIG. 3H is a cross-sectional view illustrating a
configuration example (eighth example) of a unitary unit including
the first and second grooves.
[0034] FIG. 3I is a cross-sectional view illustrating a
configuration example (ninth example) of a unitary unit including
the first and second grooves.
[0035] FIG. 4 is a diagram schematically illustrating an
arrangement example of the first grooves on the polishing surface
of the polishing pad according to the embodiment of the
invention.
DESCRIPTION OF EMBODIMENTS
[0036] Hereinafter, embodiments for carrying out the invention will
be described.
[0037] A polishing pad of the invention has at least a polishing
layer and includes a groove A (first groove) and a groove B (second
groove) formed on the polishing surface of the polishing layer. The
groove A and the groove B have side surfaces, which are continuous
with the polishing surface, on each edge in a groove width
direction. The groove A has an angle of larger than 105 degrees and
150 degrees or smaller, which is formed between the polishing
surface and the side surface continuous with the polishing surface,
on at least one edge in the groove width direction. The groove B
has an angle of 60 degrees or larger and 105 degrees or smaller,
which is formed between the polishing surface and the side surface
continuous with the polishing surface, on both of two edges in the
groove width direction.
[0038] When the groove A has an angle of larger than 105 degrees
and 150 degrees or smaller, which is formed between the polishing
surface and the side surface continuous with the polishing surface,
on at least one edge in the groove width direction, a suction force
acts between a wafer and the polishing pad and thus it can be
considered that a polishing rate is increased. In addition, by the
action of the suction force, together with an effect of bringing
the polishing pad into uniform contact within the wafer surface, it
can be considered that a high in-plane uniformity is provided to
the polishing rate of the wafer.
[0039] When the angle formed between the polishing surface and the
side surface continuous with the polishing surface is too large,
the surface area of the polishing pad is decreased. In addition,
since the cross-sectional area of the groove becomes too large,
slurry is excessively discharged and thus the polishing rate is
decreased. On the other hand, when the angle is too small, the
suction effect which the inclined side surfaces of the groove have
is not exhibited. Therefore, the angle formed between the polishing
surface and the side surface continuous with the polishing surface
needs to be larger than 105 degrees and 150 degrees or smaller, and
is preferably 110 degrees or larger, more preferably 115 degrees or
larger, and even more preferably 120 degrees or larger.
[0040] The groove A may have a bottom face. The bottom face is a
face continuous with a side opposite to the polishing surface with
respect to the side surface continuous with the polishing surface,
and a face connecting to the other side surface facing the side
surface continuous with the polishing surface.
[0041] Incidentally, the shape of the bottom face is not
particularly limited.
[0042] FIGS. 1A to 10 are diagrams illustrating specific examples
of the cross-section of the groove A.
[0043] A groove A 101 illustrated in FIG. 1A has a V-shaped
cross-section. The groove A 101 has two side surfaces 2, each of
which is continuous with a polishing surface 1, on edges thereof in
the groove width direction. In the case illustrated in FIG. 1A,
angles .theta..sub.A formed between the polishing surface and the
side surfaces continuous with the polishing surface on the two
edges in the groove width direction are equal to each other. As
described above, the value of the angle is larger than 105 degrees
and 150 degrees or smaller.
[0044] A groove A 102 illustrated in FIG. 1B has a substantially
U-shaped bottom face 3 formed between the two side surfaces 2.
[0045] A groove A 103 illustrated in FIG. 1C has a trapezoidal
cross-section and has a bottom face 4 which is formed between the
two side surfaces 2 and is parallel to the polishing surface 1.
[0046] A groove A 104 illustrated in FIG. 1D has a concave portion
5 which is formed by making a hole between the two side surfaces 2
in a direction perpendicular to the polishing surface 1. The bottom
face of the concave portion is parallel to the polishing surface
1.
[0047] Further, the side surface continuous with the polishing
surface in the groove A may be a curved line, a polygonal line, a
wavy line, or a combination thereof in addition to a straight line,
as long as the angle formed with respect to the polishing surface
on the edge can be maintained to be larger than 105 degrees and 150
degrees or smaller even when the polishing pad is worn.
[0048] Herein, it is not necessary to form the polishing pad by
using one kind of the groove A. For example, the polishing pad may
be formed by a combination of grooves having a plurality of
different cross-sections in which an angle, which is formed between
the polishing surface and the side surface continuous with the
polishing surface, on at least one edge in the groove width
direction is larger than 105 degrees and 150 degrees or smaller.
Incidentally, from the viewpoint of the in-plane uniformity, it is
preferable to form the polishing pad by using one kind of the
groove A.
[0049] At the time of polishing the polishing pad, conditioning for
dressing the pad surface by using a conditioner having diamond
arranged to a metal or ceramic pedestal is necessary. By performing
the conditioning, the surface of the polishing pad can have a
concavo-convex shape suitable for polishing and stable polishing
can be realized. However, the polishing layer is ground by the
conditioning, and the grooves thereof decrease as the polishing is
further carried out. When the cross-sectional area of the groove is
decreased, the balance between supplying and discharging of slurry
is deteriorated and thus, in some cases, there is an adverse effect
such as decrease in a polishing rate or increase in defects.
[0050] For example, in a case where the cross-section of the groove
is only V-shaped, the supplying and discharging of slurry is
sufficient at the initial period of polishing. However, in the case
of the final period in the lifetime of the polishing pad when the
polishing is further carried out and thus the cross-sectional area
of the groove is decreased, the supplying and discharging of slurry
is not performed sufficiently. Therefore, in some cases, there is a
problem that defects increase or the wafer is adsorbed on the
polishing pad.
[0051] In a case where only the groove A having the side surfaces
is arranged on the entire surface of the pad, the cross-sectional
area of the groove is decreased at the final period in the lifetime
of the polishing pad and thus, in some cases, there is a problem of
decrease in a polishing rate or increase in defects. However, by
providing the groove B in charge of the supplying and discharging
of slurry, it can be considered that a high polishing rate and
in-plane uniformity can be maintained and stable polishing can be
performed until the final period in the lifetime of the polishing
pad.
[0052] Therefore, in order to stabilize the shape of the groove B,
all angles formed between the polishing surface and "the side
surfaces of the groove B which are continuous with the polishing
surface" need to be 60 degrees or larger and 105 degrees or
smaller, and are more preferably 80 degrees or larger and even more
preferably 85 degrees or larger. In addition, the angles are more
preferably 100 degrees or smaller and even more preferably 95
degrees or smaller.
[0053] It is preferable that the groove B have a bottom face.
Incidentally, even in the case of the groove B, the shape of the
bottom face is not particularly limited.
[0054] FIGS. 2A to 2F are diagrams illustrating specific examples
of the cross-section of the groove B.
[0055] A groove B 201 illustrated in FIG. 2A has a rectangular
cross-section. The groove B 201 has two side surfaces 2, each of
which is continuous with the polishing surface 1, on edges thereof
in the groove width direction. In the case illustrated in FIG. 2A,
angles .theta..sub.B formed between the polishing surface and the
side surfaces continuous with the polishing surface on the two
edges in the groove width direction are equal to each other and the
values thereof are 90 degrees. In this case, the groove B 201 has a
rectangular cross-section and a bottom face 6 thereof is parallel
to the polishing surface 1.
[0056] A groove B 202 illustrated in FIG. 2B has a substantially
U-shaped bottom face 7 formed between the two side surfaces 2.
[0057] A groove B 203 illustrated in FIG. 2C has a concave portion
8 which is formed by making a hole between the two side surfaces 2
to be narrow-width. The bottom surface of the concave portion is
parallel to the polishing surface 1.
[0058] A groove B 204 illustrated in FIG. 2D has tapered inclined
faces 9, which are respectively continuous with the two side
surfaces 2 and are inclined to the inner periphery, and a
substantially U-shaped bottom face 10 formed between the two
inclined faces 9.
[0059] A groove B 205 illustrated in FIG. 2E has tapered inclined
faces 11, which are respectively continuous with the two side
surfaces 2 and are inclined to the inner periphery, and a V-shaped
bottom face 12 formed between the two inclined faces 11.
[0060] A groove B 206 illustrated in FIG. 2F has a bottom face 14
which is formed between two side surfaces 13 and is parallel to the
polishing surface 1. In the groove B 206, angles .theta..sub.B'
formed between the polishing surface 1 and the side surfaces 2
continuous with the polishing surface 1 are an acute angle.
[0061] Further, the side surface continuous with the polishing
surface in the groove B may be a curved line, a polygonal line, a
straight line having a plurality of folding points, a wavy line, or
a combination thereof in addition to a straight line, as long as
the angle formed with respect to the polishing surface on the edge
can be maintained to be 60 degrees or larger and 105 degrees or
smaller even when the polishing pad is worn.
[0062] Herein, it is not necessary to form the polishing pad by
using one kind of the groove B, but the polishing pad may be formed
by a combination of grooves having a plurality of different
cross-sections. Incidentally, from the viewpoint of the in-plane
uniformity, it is preferable to form the polishing pad by using one
kind of the groove.
[0063] The groove formed on the polishing surface is defined by the
area ratio of the groove formed per area of the polishing surface.
The groove-area ratio of the groove, which is formed on the
polishing surface, per unitary unit is preferably 5% or higher and
50% or lower. In particular, the lower limit of the groove-area
ratio per unitary unit is preferably 10% or higher, and more
preferably 15% or higher. In addition, the upper limit of the
groove-area ratio per unitary unit is more preferably 45% or lower,
and even more preferably 40% or lower.
[0064] The "unitary unit" is a unit formed by a combination of the
groove A and the groove B which are arranged in parallel to each
other, and grooves are formed on the entire surface of the
polishing surface by repeatedly forming the unitary unit on the
polishing surface.
[0065] FIGS. 3A to 3I are diagrams illustrating representative
examples of the configuration of a unitary unit including the
groove A and the groove B.
[0066] A unitary unit 301 illustrated in FIG. 3A includes a
combination of one groove A and three adjacent grooves B
(arrangement pattern: ABBE).
[0067] A unitary unit 302 illustrated in FIG. 3B includes a
combination of one groove A and two adjacent grooves B (arrangement
pattern: ABB).
[0068] A unitary unit 303 illustrated in FIG. 3C includes a
combination of two adjacent grooves A and three adjacent grooves B
(arrangement pattern: AABBB).
[0069] A unitary unit 304 illustrated in FIG. 3D includes a
combination of one groove A and one groove B which are adjacent to
each other (arrangement pattern: AB).
[0070] A unitary unit 305 illustrated in FIG. 3E includes a
combination of two adjacent grooves A and two adjacent grooves B
(arrangement pattern: AABB).
[0071] A unitary unit 306 illustrated in FIG. 3F includes a
combination of three adjacent grooves A and three adjacent grooves
B (arrangement pattern: AAABBB).
[0072] A unitary unit 307 illustrated in FIG. 3G includes a
combination of three adjacent grooves A and two adjacent grooves B
(arrangement pattern: AAABB).
[0073] A unitary unit 308 illustrated in FIG. 3H includes a
combination of two adjacent grooves A and one groove B (arrangement
pattern: AAB).
[0074] A unitary unit 309 illustrated in FIG. 3I includes a
combination of three adjacent grooves A and one groove B
(arrangement pattern: AAAB).
[0075] Meanwhile, an area occupying ratio of the groove A per
groove area is an area ratio of the groove A per area of groove
which is formed on the polishing surface. The area occupying ratio
of the groove A per area of groove which is formed on the polishing
surface is preferably 30% or higher and 90% or lower, more
preferably 40% or higher, and even more preferably 50% or higher.
Moreover, the area occupying ratio of the groove A per groove area
is more preferably 80% or lower, and even more preferably 70% or
lower.
[0076] A groove, which a general polishing pad may have, may be
provided on the surface of the polishing layer of the polishing pad
in a lattice form, a dimple form, a spiral form, a concentric
circle form, or the like, in order to suppress a hydroplane
phenomenon or to prevent the wafer and the pad from being sucked
with each other. A combination of these forms is preferably used,
but in particular, a lattice form is preferable. The lattice form
is a form by combining lines on a grid at a right angle. In the
lattice form, there are a plurality of cases where grooves in a
vertical direction and a horizontal direction have equal intervals,
the intervals of grooves in the vertical direction are narrower
than the intervals of grooves in the horizontal direction, and the
intervals of grooves in the horizontal direction are narrower than
the intervals of grooves in the vertical direction.
[0077] The groove A formed on the polishing surface of the
polishing pad contributes to a high polishing rate and an excellent
in-plane uniformity as described above. However, the balance
between the supplying and discharging of slurry is deteriorated in
accordance with decrease in the cross-sectional area at the final
period of lifetime of the polishing pad. According to this, defects
are increased. Therefore, for grooves formed on the polishing
surface, the sum total of groove lengths of the grooves A formed on
the entire polishing surface is preferably 10% or higher and 90% or
lower, more preferably 20% or higher, even more preferably 25% or
higher, even more preferably 30% or higher, and particularly
preferably 35% or higher of the sum total of groove lengths of the
grooves formed on the polishing surface. Moreover, the sum total of
groove lengths of the grooves A formed on the entire polishing
surface is more preferably 80% or lower, even more preferably 70%
or lower, even more preferably 60% or lower, and particularly
preferably 55% or lower.
[0078] When a ratio of the sum total of groove lengths of the
grooves A formed on the entire polishing surface to the sum total
of groove lengths of all grooves is within the above-described
range, the suction force acts between the wafer and the polishing
pad and an effect of increasing a polishing rate is exhibited.
Moreover, as a forming method of grooves formed on the polishing
surface of the polishing pad, a method may be employed in which the
groove A is formed to be concentrated on the center of the
polishing pad and the groove B is formed on the remaining portion.
When the polishing surface of the polishing pad is circular, the
groove A is formed in an area where two straight lines passing
through the center of the polishing surface and intersected with
each other are included and a distance from at least one of two
straight lines is preferably 70% or lower, more preferably 60% or
lower, even more preferably 50% or lower, and particularly
preferably 40% or lower of the radius of the polishing surface.
[0079] FIG. 4 is a diagram schematically illustrating an
arrangement example of the grooves A on the polishing surface of
the polishing pad. In a circular polishing surface 402 of a
polishing pad 401 illustrated in FIG. 4, grooves A 403 (indicated
by heavy lines) are formed in an area where two straight lines
L.sub.1 and L.sub.2 passing through the center O of the polishing
surface 402 are included and a minimum distance from at least one
of two straight lines is 1/3 (approximately 33%) or less of the
radius r. Incidentally, dashed lines illustrated in FIG. 4 indicate
grooves B 404. In this case, when an XY lattice shape is applied to
the shape of grooves, it is more preferable that the grooves A 403
be distributed in two directions perpendicular to each other (X
direction and Y direction), as compared to a case where the grooves
A 403 are concentrated in only one direction.
[0080] In a case where the groove A and the groove B are formed by
regularly arranging the grooves, the polishing pad may be formed,
for example, on the basis of any one of unitary units illustrated
in FIGS. 3A to 3H. However, a ratio of the number of the grooves A
to the number of all grooves as a combination of grooves is not
limited to exemplary combinations of grooves.
[0081] The groove widths of the groove A and the groove B are
preferably 0.1 mm or more and 10 mm or less, more preferably 0.3 mm
or more, and even more preferably 0.5 mm or more, because it is
necessary to have a cross-sectional area where slurry can be
supplied and discharged. Moreover, the groove widths of the groove
A and the groove B are more preferably 8 mm or less, and even more
preferably 5 mm or less.
[0082] The groove depths of the groove A and the groove B are
preferably 0.2 mm or more and 4 mm or less, more preferably 0.3 mm
or more, and even more preferably 0.4 mm or more, because it is
necessary to secure supplying and discharging of slurry and
sufficient lifetime. Moreover, the groove depths of the groove A
and the groove B are more preferably 3 mm or less, and even more
preferably 2 mm or less.
[0083] It is sufficient that the thickness of the polishing layer
is smaller than a distance from the upper surface of the platen of
the polishing apparatus to the lower surface of the polishing head.
Therefore, the thickness of the polishing layer is preferably 4.0
mm or less, more preferably 3.5 mm or less, even more preferably
3.0 mm or less, and particularly preferably 2.5 mm or less.
[0084] In the invention, as the polishing layer that forms the
polishing pad, a structure having the micro-rubber A hardness of 70
degrees or higher and isolated bubbles forms a planar surface on
semiconductors, dielectric material/metal composites, integrated
circuits and the like. Therefore, the structure is preferable.
Although there are no particular limitations in terms of a material
for forming the structure, examples of the material include
polyethylene, polypropylene, polyester, polyurethane, polyurea,
polyamide, polyvinyl chloride, polyacetal, polycarbonate,
polymethyl methacrylate, polytetrafluoroethylene, epoxy resin, ABS
resin, AS resin, phenol resin, melamine resin, "Neoprene
(registered trademark)" rubber, butadiene rubber, styrene butadiene
rubber, ethylene propylene rubber, silicon rubber, fluorine rubber,
and resin having one of these as a main component. Among these, two
or more materials may be used. Among these resins, a material
having polyurethane as a main component is more preferable in terms
of the fact that a diameter of isolated bubbles can be controlled
relatively easily.
[0085] Polyurethane means a polymer synthesized by inducing
addition polymerization reaction or a polymerization reaction using
polyisocyanate. Examples of polyisocyanate may include tolylene
diisocyanate, diphenylmethane diisocyanate, naphthalene
diisocyanate, hexamethylene diisocyanate, and isophorone
diisocyanate. However, polyisocyanate is not limited to these and
two or more of these may be used. The compound to be used as a
reactant with polyisocyanate is a compound containing active
hydrogen, that is, a compound that contains two or more polyhydroxy
groups or an amino group. Polyol is typically used as a compound
containing a polyhydroxy group, and examples thereof include
polyether polyol, polytetramethylene ether glycol, epoxy resin
modified polyol, polyester polyol, acryl polyol, polybutadiene
polyol, and silicone polyol. Two or more of these may be used. It
is preferable to determine a combination of polyisocyanate and
polyol, and a catalyst, a foaming agent and a foam stabilizer and
optimal amounts thereof on the basis of hardness, a diameter of
bubbles and an expansion ratio.
[0086] As a method for forming isolated bubbles in the
polyurethane, a chemical foaming method for mixing various types of
foaming agents with the resin at the time of manufacturing
polyurethane is generally used, but a method for foaming a resin by
mechanically stirring and then curing the resin can be also
appropriate for use.
[0087] An average diameter of isolated bubbles is preferably 20
.mu.m or greater and more preferably 30 .mu.m or greater, from the
viewpoint of holding slurry on the surface of the pad. Meanwhile,
the average diameter of isolated bubbles is preferably 150 .mu.m or
less, more preferably 140 .mu.m or less, and even more preferably
130 .mu.m or less, from the viewpoint of securing the local
planarity of unevenness on a semiconductor substrate. Incidentally,
the average diameter of bubbles is a value obtained by observing
the cross-section of a sample through an ultra-depth profile
measuring microscope VK-8500 manufactured by Keyence Corporation at
a magnification of 400 times, measuring an equivalent circle
diameter of circular bubbles, which are obtained by excluding
circularly-deficient bubbles observed outside of the field of view
from bubbles observed in one field of view, from a cross-sectional
area by using an image processing apparatus, and calculating an
average value.
[0088] As an embodiment of the polishing pad according to the
invention, a pad, which contains polyurethane and a polymer
obtained by polymerizing a vinyl compound and has isolated bubbles,
is preferable. By containing only the polymer obtained by
polymerizing a vinyl compound, toughness and hardness can be
increased, but it is difficult to obtain a uniform polishing pad
having isolated bubbles. Moreover, polyurethane becomes fragile as
the hardness increases. By impregnating polyurethane with the vinyl
compound, it is possible to obtain a polishing pad containing
isolated bubbles and having a high toughness and hardness.
[0089] The vinyl compound is a compound having a polymeric
carbon-carbon double bond. Specific examples thereof include methyl
acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,
n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate,
isodecyl methacrylate, isobutyl methacrylate, n-lauryl
methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl
methacrylate, 2-hydroxybutyl methacrylate, dimethylaminoethyl
methacrylate, diethylaminoethyl methacrylate, glycidyl
methacrylate, ethylene glycol dimethacrylate, acrylic acid,
methacrylic acid, fumaric acid, dimethyl fumarate, diethyl
fumarate, dipropyl fumarate, maleate, dimethyl maleate, diethyl
maleate, dipropyl maleate, phenylmaleimide, cyclohexylmaleimide,
isopropylmaleimide, acrylonitrile, acrylamide, vinyl chloride,
vinylidene chloride, styrene, a-methyl styrene, divinylbenzene,
ethylene glycol dimethacrylate, and diethylene glycol
dimethacrylate. Moreover, two or more of these may be used as the
vinyl compound.
[0090] Among the above-described vinyl compounds,
CH.sub.2=CR.sup.1COOR.sup.2 (R.sup.1: a methyl group or an ethyl
group, R.sup.2: a methyl group, an ethyl group, a propyl group or a
butyl group) is preferable. Among these, methyl methacrylate, ethyl
methacrylate, n-butyl methacrylate, and isobutyl methacrylate are
preferable, from the viewpoints that isolated bubbles are easily
formed in polyurethane, the impregnating ability of monomers is
preferable, polymerization curing is easy, and a foaming structure
containing polyurethane and a polymer obtained by polymerizing a
polymerization cured vinyl compound has a high hardness and
planarization characteristics.
[0091] Examples of a polymerization initiator which can be
preferably used to obtain the polymer obtained by polymerizing a
vinyl compound may include radical initiators such as
azobisisobutylonitrile, azobis(2,4-dimethylvaleronitrile),
azobiscyclohexane carbonitrile, benzoyl peroxide, lauroyl peroxide,
and isopropyl peroxydicarbonate. Two or more of these may be used.
In addition, an oxidation-reduction based polymerization initiator,
for example, a combination of peroxide and amines may be also
used.
[0092] As a method for impregnating polyurethane with a vinyl
compound, a method for immersing polyurethane in a container
including a vinyl compound can be exemplified. Further, at this
time, it is preferable to perform a process such as heat
application, pressure application, pressure reduction, stirring,
vibration, and ultrasonic vibration, for the purpose of increasing
a rate of impregnation.
[0093] An impregnated amount of the vinyl compound in the
polyurethane should be determined on the basis of types of a vinyl
compound and polyurethane to be used, or properties of a polishing
pad to be manufactured. Although it depends on circumstances, for
example, a content ratio of a polymer obtained from a vinyl
compound in the polymerization cured foaming structure and the
polyurethane is preferably 30/70 to 80/20 in terms of a weight
ratio. When the content ratio of the polymer obtained from a vinyl
compound is 30/70 or more in terms of a weight ratio, the hardness
of the polishing pad can be increased sufficiently. Moreover, when
the content ratio thereof is 80/20 or less, the elasticity of the
polishing layer can be increased sufficiently.
[0094] The contents of the polyurethane and the polymer obtained
from the polymerization cured vinyl compound in the polyurethane
can be measured by pyrolysis gas chromatography/mass spectrometry.
As an apparatus used for this technique, a double shot pyrolizer
"PY-2010D" (manufactured by Frontier Laboratories Ltd.) may be used
as a pyrolytic equipment, and "TRIO-1" (manufactured by VG Co.,
Ltd.) may be used as a gas chromatography/mass spectrometry
equipment.
[0095] In the invention, it is preferable that the phase of the
polyurethane and the phase of the polymer obtained from a vinyl
compound be contained in a non-separated state, form the viewpoint
of the local planarity of unevenness on the semiconductor
substrate. Quantitatively speaking, "an infrared spectrum obtained
when the polishing pad is observed with a microscopic infrared
spectrometer having a spot size of 50 .mu.m has an infrared
absorption peak of the polymer polymerized from a vinyl compound
and an infrared absorption peak of the polyurethane, and the
infrared spectrum is approximately the same in various places". As
a microscopic infrared spectrometer used herein, IR.mu.s
manufactured by SPECTRA-TEC Inc., may be used.
[0096] The polishing pad may contain various types of additives,
such as a polishing agent, a charge preventing agent, a lubricant,
a stabilizer or a dye, for the purpose of improving properties of
the polishing pad.
[0097] In the invention, a micro-rubber A hardness of the polishing
layer is a value obtained by evaluation using a micro-rubber
hardness meter MD-1 manufactured by KOBUNSHI KEIKI CO., LTD. The
micro-rubber A hardness meter MD-1 makes measurement of the
hardness of thin or small objects which are difficult to measure
using a conventional hardness meter possible. Since the
micro-rubber A hardness meter MD-1 is designed and manufactured as
a scaled-down model of approximately 1/5 of a type A spring-type
rubber hardness meter (durometer), it is possible to obtain a
measurement value which coincides with the hardness measured using
a type A spring-type hardness meter. A conventional polishing pad
has a polishing layer or a hard layer of which a thickness is less
than 5 mm, and thus cannot be evaluated using a type A spring-type
rubber hardness meter. Accordingly, in the invention, the
micro-rubber A hardness of the polishing layer is evaluated using
the above-described micro-rubber MD-1.
[0098] In the invention, the hardness of the polishing layer is
preferably 70 degrees or higher, and more preferably 80 degrees or
higher in terms of the micro-rubber A hardness, from the viewpoint
of the local planarity or unevenness on the semiconductor
substrate.
[0099] In the invention, the density of the polishing layer is
preferably 0.3 g/cm.sup.3 or higher, more preferably 0.6 g/cm.sup.3
or higher, and even more preferably 0.65 g/cm.sup.3 or higher, from
the viewpoint of reducing defects in the local planarity, or global
level differences. Meanwhile, the density of the polishing layer is
preferably 1.1 g/cm.sup.3 or lower, more preferably 0.9 g/cm.sup.3
or lower, and even more preferably 0.85 g/cm.sup.3 or lower, from
the viewpoint of reducing scratches. Incidentally, the density of
the polishing layer according to the invention is a value which is
measured with water as a medium, using a Harvard type pycnometer
(JIS R-3503 standard).
[0100] It is preferable that the polishing pad according to the
invention have a cushion layer of which a volume modulus of
elasticity is 40 MPa or higher and a tensile modulus of elasticity
is 1 MPa or higher and 20 MPa or lower, from the viewpoint of
making the in-plane uniformity excellent. The volume modulus of
elasticity is obtained in such a manner that the change in volume
is measured by applying isotropic pressure to an object to be
measured, of which the volume has been measured in advance, and
calculation is carried out on the basis of the measurement result
using the formula "volume modulus of elasticity=applied
pressure/(change in volume/original volume). In the invention, the
volume modulus of elasticity means a value measured when a sample
is applied with a pressure of 0.04 to 0.14 MPa at 23.degree. C.
[0101] In the invention, the volume modulus of elasticity is
measured as follows. A test piece and water of 23.degree. C. are
put in a measurement cell made of stainless steel having an
internal volume of approximately 40 mL, and a measuring pipette
made of borosilicate glass having a volume of 0.5 mL (minimum
scale: 0.005 mL) is installed. A tube made of a polyvinyl chloride
resin (inner diameter: 90 mm.phi..times.2000 mm, thickness: 5 mm)
is separately used as a pressure container, the measurement cell in
which the above-described test piece has been put is put therein,
and a pressure P is applied using nitrogen, so that a change in
volume V1 is measured. Subsequently, the pressure P is applied
using nitrogen without putting the test piece in the measurement
cell so that a change in volume V0 is measured. A value obtained by
dividing the pressure P by .DELTA.V/Vi=(V1-V0)/Vi is calculated as
the volume modulus of elasticity of the sample.
[0102] In the invention, the volume modulus of elasticity of the
cushion layer is preferably 40 MPa or higher. When the volume
modulus of elasticity is 40 MPa or higher, the in-plane uniformity
on the entire surface of the semiconductor substrate can be
enhanced. Moreover, it is difficult that the cushion layer is
impregnated with slurry or water which flows into a hole that
penetrates through the polishing pad from the front surface to the
rear surface and thus a cushioning property can be maintained.
[0103] In the invention, the tensile modulus of elasticity is
obtained in such a manner that a tensile stress is applied to a
test piece in a dumbbell form, and the tensile stress is measured
for a tensile distortion (=change in the tensile length/original
length) in a range from 0.01 to 0.03 and calculation is carried out
on the basis of the measurement result using the formula "tensile
modulus of elasticity=((tensile stress when the tensile distortion
is 0.03)-(tensile stress when the tensile distortion is
0.01))/0.02". As an apparatus for measuring the tensile stress,
Tensilon Multi-Purpose Tester RTM-100 manufactured by Orientec Co.,
Ltd. or the like may be used. As for measuring conditions of the
tensile stress, a rate of testing is 5 cm/min and the test piece is
in a dumbbell form with a width of 5 mm, and a sample length of 50
mm.
[0104] In the invention, the tensile modulus of elasticity of the
cushion layer is preferably 1 MPa or higher, and more preferably
1.2 MPa or higher, from the viewpoint of the in-plane uniformity on
the entire surface of the semiconductor substrate. The tensile
modulus of elasticity of the cushion layer is preferably 20 MPa or
lower, and more preferably 10 MPa or lower.
[0105] As such a cushion layer, unfoamed elastomers, such as
natural rubber, nitrile rubber, "Neoprene (registered trademark)"
rubber, polybutadiene rubber, thermosetting polyurethane rubber,
thermoplastic polyurethane rubber or silicon rubber, may be used,
but there are no limitations to these. A thickness of the cushion
layer is preferably in a range from 0.1 to 2 mm. A thickness of the
cushion layer is preferably 0.2 mm or more, and more preferably 0.3
mm or more, from the viewpoint of the in-plane uniformity on the
entire surface of the semiconductor substrate. Moreover, a
thickness of the cushion layer is preferably 2 mm or less, and more
preferably 1.75 mm or less, from the viewpoint of the local
planarity.
[0106] As means for pasting the polishing layer and the cushion
layer, for example, a double-sided tape or an adhesive may be
used.
[0107] The double-sided tape has a general configuration in which
an adhesive layer is provided on the both surfaces of a base
material such as non-woven fabric or a film. Moreover, the
polishing pad of the invention may include a double-sided tape
formed on a surface to which a platen of the cushion sheet is
attached. As such a double-sided tape, a double-sided tape having a
general configuration in which an adhesive layer is provided on the
both surfaces of a base material in the same manner as described
above may be used. As a base material, for example, non-woven
fabric or a film may be used. In consideration of peeling the
polishing pad from the platen after using the polishing pad, a film
is preferably used as a base material.
[0108] Further, as a composition of the adhesive layer, for
example, a rubber-based adhesive, an acrylic-based adhesive, or the
like may be used. In consideration of a content of metal ions, an
acrylic-based adhesive is preferable in terms of a small content of
metal ions. Moreover, in many cases, the cushion sheet has a
different composition from the platen. Thus, compositions of
respective adhesive layers of the double-sided tape make different
from each other and it is also possible to make an adhesive force
to the cushion sheet and the platen proper.
[0109] In the invention, as a material to be polished, for example,
the surface of an insulating layer and metal wires formed on a
semiconductor wafer may be used. Examples of the insulating layer
may include interlayer insulating films of metal wires, lower layer
insulating films of metal wires, and shallow trench isolation used
for element isolation. Examples of the metal wires include aluminum
wires, tungsten wires, and copper wires having a damascene, dual
damascene, or plug structure. In a case where metal wires are made
of copper, a barrier metal made of silicon nitride or the like also
becomes an object to be polished. Although insulating films made of
silicon oxide are currently used as mainstream insulating films,
low dielectric constant insulating films may also be used. The
material to be polished can be used for polishing magnetic heads,
hard discs, and sapphire, in addition to semiconductor wafers.
[0110] The polishing method of the invention is preferably used to
form a planar surface on glass, semiconductors, dielectric
material/metal composites, integrated circuits, and the like.
EXAMPLES
[0111] Hereinafter, the detail description of the invention will be
made on the basis of Examples. However, it should be understood
that the invention is not limited to Examples. Incidentally,
measurement was carried out as follows.
[0112] <Inclination Angle Measurement>
[0113] An angle formed between the polishing surface and the side
surface continuous with the polishing surface was measured in such
a manner that the polishing pad including the groove formed on the
surface of the polishing layer was sliced in the groove depth
direction and the cross-section of the groove was observed through
an ultra-depth profile measuring microscope VK-8500 manufactured by
Keyence Corporation. In a case where the polishing pad is circular,
the nearest grooves from positions at 50 mm, 150 mm, and 250 mm
distant from the center of the polishing pad were measured and an
average of these three points was set as an inclination angle.
Meanwhile, in a case where the polishing pad is not circular, the
nearest grooves from positions at 50 mm, 150 mm, and 250 mm distant
from an intersection point of diagonal lines of the sheet toward
one end thereof were measured and an average of these three points
was set as an inclination angle.
[0114] <Average Polishing Rate Measurement and In-Plane
Uniformity>
[0115] The polishing was carried out using Mirra 3400 manufactured
by Applied Material Co., Ltd. under a predetermined polishing
condition while performing endpoint detection. An average polishing
rate as polishing characteristics was obtained in such a manner
that polishing rates (nm/min) were measured by excluding 10 mm of
the outmost circumference of the 8-inch wafer. The in-plane
uniformity was obtained by dividing the standard deviation of the
polishing rate by a difference between the maximum value and the
minimum value of the polishing rates.
[0116] <Defect Evaluation>
[0117] As an enhancement process, after the polished wafer was
immersed for 10 minutes in 0.5% by weight of hydrofluoric acid and
then washed with water, the wafer was washed with a mixture
solution of 1.0% by weight of ammonia and 1.0% by weight of
hydrogen peroxide and then washed with water to be dried. The
number of defects of 0.155 lam or greater was counted on the washed
wafer, using SP-1 manufactured by KLA-Tencor Co., Ltd.
[0118] <Pad Grinding Rate>
[0119] The depth of the groove before and after polishing was
measured using a depth gauge (digimatic type) manufactured by
Mitutoyo Corporation, and a pad grinding rate was obtained by
dividing a reduced value of the groove by a time of using a disk
which was being evaluated.
[0120] <Ratio of the Number of Grooves A>
[0121] The polishing pad including the groove formed on the
polishing surface was sliced in parallel to the groove so as to
count the number of the grooves A and the grooves B. Further, the
ratio of the number of the grooves A was obtained in such a manner
that the sum of the number of the groove A and the groove B was
obtained from the arrangement example of the groove A and the
groove B (cross-sectional view: FIG. 3) and the arrangement example
of the groove A and the groove B (pattern diagram: FIG. 4) and the
number of the grooves A was divided by the sum of the number of the
groove A and the groove B. The calculation formula is described
below.
Ratio of the number of the grooves A=the number of the grooves
A/(the number of the grooves A+the number of the grooves
B).times.100 (%)
[0122] Hereinafter, Examples 1 to 11 and Comparative Examples 1 to
3 will be described.
Example 1
[0123] 30 parts by weight of polypropylene glycol, 40 parts by
weight of diphenylmethane diisocyanate, 0.5 part by weight of
water, 0.3 part by weight of triethylamine, 1.7 parts by weight of
a silicon foam stabilizer, and 0.09 part by weight of tin octylate
were mixed in an RIM molding machine, and the mixture was
discharged into a mold for pressure molding to manufacture a foam
polyurethane sheet with isolated bubbles having a thickness of 2.6
mm (micro-rubber A hardness: 42 degrees, density: 0.76 g/cm.sup.3,
average diameter of isolated bubbles: 34 .mu.m).
[0124] The above-described foam polyurethane sheet was immersed for
60 minutes in methyl methacrylate to which 0.2 part by weight of
azobisisobutylonitrile was added. Next, the above-described foam
polyurethane sheet was immersed in a solution of 15 parts by weight
of polyvinyl alcohol "CP" (degree of polymerization: approximately
500, manufactured by Nacalai Tesque, Inc.), 35 parts by weight of
ethyl alcohol (special class reagent produced by Katayama Chemical
Industries Co., Ltd.) and 50 parts by weight of water, and after
that dried, and thus, the surface layer of the above-described foam
polyurethane sheet was coated with polyvinyl alcohol.
[0125] Next, the above-described foam polyurethane sheet was
sandwiched between two glass plates via a gasket made of vinyl
chloride, and heated for six hours at 65.degree. C. and for three
hours at 120.degree. C. so as to be cured through polymerization.
The sheet was removed from the glass plates and washed with water,
and after that dried in a vacuum at 50.degree. C. The hard foam
sheet thus obtained was sliced to have a thickness of 2.00 mm, and
thus a polishing layer was manufactured. The content of methyl
methacrylate in the polishing layer was 66% by weight. In addition,
the D hardness of the polishing layer was 54 degrees, the density
thereof was 0.81 g/cm.sup.3, and the average diameter of the
isolated bubbles was 45 Rm.
[0126] The both sides of the hard foam sheet thus obtained were
ground to manufacture a polishing layer having a thickness of 2
mm.
[0127] The polishing layer obtained by the above-described method
was layered with thermoplastic polyurethane produced by Nihon Matai
Co., Ltd. having a micro-rubber A hardness of 90 degrees and a
thickness of 0.3 mm (volume modulus of elasticity=65 MPa, tensile
modulus of elasticity=4 MPa), which functioned as a cushion layer,
via an adhesive layer MA-6203 manufactured by Mitsui Chemicals
Polyurethanes, Inc. using a roll coater, and furthermore, a
double-sided tape 5604TDM manufactured by Sekisui Chemical Co.,
Ltd., was pasted on the rear surface as a rear surface tape.
[0128] The groove A, which has a groove width of 3.0 mm, a groove
pitch of 15 mm, a V-shaped cross-section with an inclination angle
.theta..sub.A of 135 degrees, and a groove depth of 1.5 mm, and the
groove B, which has a groove width of 1.5 mm, a groove pitch of 15
mm, and a rectangular cross-section with a groove depth of 1.5 mm
(inclination angle .theta..sub.B=90 degrees) were alternately
repeated (hereinafter, referred to as a pattern A) to be formed in
the XY lattice shape. Therefore, the polishing pad was obtained. A
groove-area ratio of the groove A per unitary unit was 24.9% and an
area occupying ratio of the groove A per groove area was 73.7%.
[0129] The polishing pad obtained by the above-described method was
pasted on the platen of a polishing apparatus ("Mirra 3400"
manufactured by Applied Materials, Inc.). 100 pieces of 8-inch
wafer with an oxide film were polished under a retainer ring
pressure of 41 kPa (6 psi), an inner tube pressure of 28 kPa (4
psi), a membrane pressure of 28 kPa (4 psi), the number of
rotations of platen of 76 rpm and the number of rotations of the
polishing head of 75 rpm, and with slurry (SS-25, produced by Cabot
Corporation) flowing at a flowing rate of 150 mL/min, by using a
dresser manufactured by Saesol Diamond ind. Co., Ltd. under a load
of 17.6 N (4 lbf) and for a polishing time of one minute, and by
performing in-situ dressing for 30 seconds after the start of
polishing. The average polishing rate of the 100th oxide film was
202 nm/min and the in-plane uniformity was 11.8%.
[0130] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 331, which was very excellent. In addition,
the pad grinding rate during polishing was 1.01 .mu.m/min.
Example 2
[0131] The polishing was carried out in the same manner as Example
1, except that grooves of the polishing surface were configured to
include the groove A, which has a groove width of 3.0 mm, a groove
pitch of 15 mm, a V-shaped cross-section with an inclination angle
.theta..sub.A of 135 degrees, and a groove depth of 1.5 mm, and the
groove B, which has a groove width of 1.5 mm, a groove pitch of 15
mm, and a rectangular cross-section with a groove depth of 1.5 mm,
and a combination of one groove A and two grooves B was repeated
(hereinafter, referred to as a pattern B) to be formed in the XY
lattice shape over the entire area in the radius of the pad from
the center of the polishing surface of the polishing pad. The
groove-area ratio of the groove A per unitary unit was 20.7%, and
the area occupying ratio of the groove A per groove area was 60.9%.
The average polishing rate was 197 nm/min, and the in-plane
uniformity was 9.0%.
[0132] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 211, which was excellent. In addition, the
pad grinding rate during polishing was 1.21 .mu.m/min.
Example 3
[0133] The polishing was carried out in the same manner as Example
1, except that the polishing pad was configured in such a manner
that, on the surface of the polishing layer, the groove A, which
has a groove width of 3.0 mm, a groove pitch of 15 mm, a V-shaped
cross-section with an inclination angle .theta..sub.A of 135
degrees, and a groove depth of 1.5 mm, was formed in the XY lattice
shape in an area where two straight lines passing through the
center of the polishing surface and intersected with each other are
included and a distance from at least one straight line is 32% or
lower of the radius of the polishing surface, and the groove B,
which has a groove width of 1.5 mm, a groove pitch of 15 mm, and a
rectangular cross-section with a groove depth of 1.5 mm, was formed
in the XY lattice shape in an area where a distance from the
diameter exceeds 32% of the radius (hereinafter, referred to as a
pattern C). The groove-area ratio of the groove A per unitary unit
was 23.1%, and the area occupying ratio of the groove A per groove
area was 67.7%. The arrangement diagram of grooves is illustrated
in FIG. 4. The average polishing rate was 196 nm/min, and the
in-plane uniformity was 10.9%.
[0134] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 142, which was very excellent. In addition,
the pad grinding rate during polishing was 1.34 .mu.m/min.
Example 4
[0135] The polishing was carried out in the same manner as Example
1, except that the groove A was formed on the surface of the
polishing layer to have a trapezoidal cross-section with an
inclination angle .theta..sub.A of 120 degrees. The groove-area
ratio of the groove A per unitary unit was 16.5%, and the area
occupying ratio of the groove A per groove area was 54.8%. The
average polishing rate was 199 nm/min, and the in-plane uniformity
was 6.0%.
[0136] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 155, which was very excellent. In addition,
the pad grinding rate during polishing was 1.14 .mu.m/min.
Example 5
[0137] The polishing was carried out in the same manner as Example
4, except that the groove A was formed on the surface of the
polishing layer to have a trapezoidal cross-section with an
inclination angle .theta..sub.A of 123 degrees. The groove-area
ratio of the groove A per unitary unit was 28.3%, and the area
occupying ratio of the groove A per groove area was 73.6%. The
average polishing rate was 203 nm/min, and the in-plane uniformity
was 8.4%.
[0138] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 141, which was very excellent. In addition,
the pad grinding rate during polishing was 1.32 .mu.m/min.
Example 6
[0139] The polishing was carried out in the same manner as Example
4, except that the groove B was formed on the surface of the
polishing layer to have a trapezoidal cross-section with an
inclination angle .theta..sub.B of 85 degrees. The groove-area
ratio of the groove A per unitary unit was 30.2%, and the area
occupying ratio of the groove A per groove area was 68.9%. The
average polishing rate was 201 nm/min, and the in-plane uniformity
was 9.1%.
[0140] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 139, which was very excellent. In addition,
the pad grinding rate during polishing was 1.11 .mu.m/min.
Example 7
[0141] The polishing was carried out in the same manner as Example
3, except that, on the surface of the polishing layer, the groove A
was formed to have a V-shaped cross-section with an inclination
angle .theta..sub.A of 120 degrees and the groove B was formed to
have a trapezoidal cross-section with an inclination angle
.theta..sub.B of 85 degrees. The groove-area ratio of the groove A
per unitary unit was 16.5%, and the area occupying ratio of the
groove A per groove area was 54.8%. The average polishing rate was
200 nm/min, and the in-plane uniformity was 9.8%.
[0142] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 211, which was very excellent. In addition,
the pad grinding rate during polishing was 1.33 .mu.m/min.
Example 8
[0143] The polishing was carried out in the same manner as Example
3, except that, on the surface of the polishing layer, the groove A
was formed to have a V-shaped cross-section with an inclination
angle .theta..sub.A of 120 degrees and the groove B was formed to
have a trapezoidal cross-section with an inclination angle
.theta..sub.B of 95 degrees. The groove-area ratio of the groove A
per unitary unit was 18.4%, and the area occupying ratio of the
groove A per groove area was 49.0%. The average polishing rate was
209 nm/min, and the in-plane uniformity was 10.1%.
[0144] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 109, which was very excellent. In addition,
the pad grinding rate during polishing was 1.30 .mu.m/min.
Example 9
[0145] The polishing was carried out in the same manner as Example
3, except that the groove A was formed on the surface of the
polishing layer to have a V-shaped cross-section with an
inclination angle .theta..sub.A of 150 degrees. The groove-area
ratio of the groove A per unitary unit was 34.6%, and the area
occupying ratio of the groove A per groove area was 78.4%. The
average polishing rate was 200 nm/min, and the in-plane uniformity
was 9.9%.
[0146] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 111, which was very excellent. In addition,
the pad grinding rate during polishing was 1.41 .mu.l/min.
Example 10
[0147] The polishing was carried out in the same manner as Example
3, except that, on the surface of the polishing layer, the groove A
was formed to have a V-shaped cross-section with an inclination
angle .theta..sub.A of 150 degrees and the groove B was formed to
have a trapezoidal cross-section with an inclination angle
.theta..sub.B of 85 degrees. The groove-area ratio of the groove A
per unitary unit was 34.6%, and the area occupying ratio of the
groove A per groove area was 78.4%. The average polishing rate was
206 nm/min, and the in-plane uniformity was 10.0%.
[0148] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 153, which was very excellent. In addition,
the pad grinding rate during polishing was 1.44 .mu.m/min.
Example 11
[0149] The polishing was carried out in the same manner as Example
3, except that, on the surface of the polishing layer, the groove A
was formed to have a V-shaped cross-section with an inclination
angle .theta..sub.A of 150 degrees and the groove B was formed to
have a trapezoidal cross-section with an inclination angle
.theta..sub.B of 95 degrees. The groove-area ratio of the groove A
per unitary unit was 36.5%, and the area occupying ratio of the
groove A per groove area was 74.3%. The average polishing rate was
200 nm/min, and the in-plane uniformity was 10.1%.
[0150] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 134, which was very excellent. In addition,
the pad grinding rate during polishing was 1.40 .mu.m/min.
Comparative Example 1
[0151] The polishing was carried out in the same manner as Example
1, except that only grooves, which have a groove width of 1.5 mm, a
groove pitch of 15 mm, and a rectangular cross-section with a
groove depth of 1.5 mm, were formed on the surface of the polishing
layer. The average polishing rate was 180 nm/min, and the in-plane
uniformity was 12.2%.
[0152] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 583, which was excellent. In addition, the
pad grinding rate during polishing was 1.13 .mu.m/min.
Comparative Example 2
[0153] The polishing was carried out in the same manner as Example
1, except that only grooves, which have a groove width of 3.0 mm, a
groove pitch of 15 mm, a groove depth of 1.5 mm, and a V-shaped
cross-section with an inclination angle of 135 degrees, were formed
on the surface of the polishing layer. The average polishing rate
was 217 nm/min, and the in-plane uniformity was 21.1%.
[0154] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 297, which was very excellent. In addition,
the pad grinding rate during polishing was 1.73 .mu.m/min.
Comparative Example 3
[0155] The polishing was carried out in the same manner as Example
1, except that the polishing layer was formed to have a thickness
of 1.0 mm, and only grooves, which have a groove width of 1.0 mm, a
groove pitch of 15 mm, a groove depth of 0.5 mm, and a V-shaped
cross-section with an inclination angle of 135 degrees, were formed
on the surface of the polishing layer. The average polishing rate
was 205 nm/min, and the in-plane uniformity was 18.3%.
[0156] When the number of defects of 0.155 .mu.m or greater was
counted on the polished wafer by the defect evaluation method, the
number of defects was 1521, which was a large number of defects. In
addition, the pad grinding rate during polishing was 1.68
.mu.m/min.
[0157] The results obtained from Examples 1 to 11 and Comparative
Examples 1 to 3 described above are listed in Table 1.
TABLE-US-00001 TABLE 1 Comparative Comparative Comparative Example
1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7
Example 8 Example 9 Example 10 Example 11 Example 1 Example 2
Example 3 Cross-section V V V Trapezoidal Trapezoidal Trapezoidal V
V V V V Rectangular V V of groove A Inclination 135 135 135 120 123
120 120 120 150 150 150 90 135 135 angle .theta..sub.A of groove A
(degree) Cross-section Rectangular Rectangular Rectangular
Rectangular Rectangular Trapezoidal Trapezoidal Trapezoidal
Rectangular Trapezoidal Trapezoidal -- -- -- of groove B
Inclination 90 90 90 90 90 85 85 95 90 85 95 -- -- -- angle
.theta..sub.B of groove B (degree) Groove A B C A A A C C C C C --
-- -- arrangement pattern Groove-area 24.9 20.7 23.1 16.5 28.3 30.2
16.5 18.4 34.6 34.6 36.5 -- -- -- ratio of groove A per unitary
unit (%) Area 73.7 60.9 67.7 54.8 73.6 68.9 54.8 49.0 78.4 78.4
74.3 -- -- -- occupying ratio of groove A per groove area (%)
Average 202 197 196 199 203 201 200 209 200 206 200 180 217 205
polishing rate (nm/min) In-plane 11.8 9.0 10.9 6.0 8.4 9.1 9.8 10.1
9.9 10.0 10.1 12.2 21.1 18.3 uniformity (%) Defect 331 211 142 155
141 139 211 109 111 153 134 583 297 1521 Pad grinding 1.01 1.21
1.34 1.14 1.32 1.11 1.33 1.30 1.41 1.44 1.40 1.13 1.73 1.68 rate
(.mu.m/min)
REFERENCE SIGNS LIST
[0158] 1, 402 POLISHING SURFACE [0159] 2, 13 SIDE SURFACE [0160] 3,
4, 6, 7, 8, 10, 12, 14 BOTTOM FACE [0161] 5 CONCAVE PORTION [0162]
9, 11, 13 INCLINED FACE [0163] 101, 102, 103, 104, 403 GROOVE A
[0164] 201, 202, 203, 204, 205, 206, 404 GROOVE B [0165] 301, 302,
303, 304, 305, 306, 307, 308, 309 UNITARY UNIT [0166] 401 POLISHING
PAD
* * * * *