U.S. patent application number 10/451644 was filed with the patent office on 2004-04-15 for cmp conditioner, method for arranging rigid grains used for cmp conditioner, and method for manufacturing cmp conditioner.
Invention is credited to Araki, Ryuichi, Hashino, Eiji, Kinoshita, Toshiya, Sato, Setsuo.
Application Number | 20040072510 10/451644 |
Document ID | / |
Family ID | 26606289 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040072510 |
Kind Code |
A1 |
Kinoshita, Toshiya ; et
al. |
April 15, 2004 |
Cmp conditioner, method for arranging rigid grains used for cmp
conditioner, and method for manufacturing cmp conditioner
Abstract
Disclosed are CMP conditioners which can suppress
microscratching of the surface of a semiconductor substrate and can
realize stable CMP conditioner properties. The CMP conditioner
according to the first aspect of the present invention comprises a
support member and a plurality of hard abrasive grains provided on
a surface of the support member, wherein the plurality of hard
abrasive grains are regularly arranged on the surface of the
support member. The CMP conditioner according to the second aspect
of the present invention comprises a support member and a plurality
of hard abrasive grains provided on the surface of the support
member, wherein the plurality of hard abrasive grains are arranged
on the surface of the support member regularly and so as for the
density of the hard abrasive grains to decrease from the inner side
of the support member toward the outer side of the support
member.
Inventors: |
Kinoshita, Toshiya;
(Tokyo-To, JP) ; Hashino, Eiji; (Chiba-Ken,
JP) ; Sato, Setsuo; (Chiba-Ken, JP) ; Araki,
Ryuichi; (Chiba-Ken, JP) |
Correspondence
Address: |
Kenyon & Kenyon
One Broadway
New York
NY
10004
US
|
Family ID: |
26606289 |
Appl. No.: |
10/451644 |
Filed: |
June 19, 2003 |
PCT Filed: |
December 20, 2001 |
PCT NO: |
PCT/JP01/11209 |
Current U.S.
Class: |
451/56 ;
451/548 |
Current CPC
Class: |
B24D 18/00 20130101;
B24B 53/017 20130101; B24D 3/06 20130101; B24B 53/12 20130101; B24D
7/14 20130101; B24D 3/14 20130101 |
Class at
Publication: |
451/056 ;
451/548 |
International
Class: |
B24B 001/00; B24B
033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2000 |
JP |
2000-388994 |
Aug 30, 2001 |
JP |
2001-262167 |
Claims
1. A CMP conditioner comprising: a support member; and a plurality
of hard abrasive grains provided on a surface of the support
member, wherein said plurality of hard abrasive grains are
regularly arranged on the surface of the support member.
2. The CMP conditioner according to claim 1, wherein said hard
abrasive grains are arranged at respective lattice points of a unit
lattice formed of a square on the surface of the support
member.
3. The CMP conditioner according to claim 1, wherein said hard
abrasive grains are arranged at respective lattice points of a unit
lattice formed of a regular triangle on the surface of the support
member.
4. A CMP conditioner comprising: a support member; and a plurality
of hard abrasive grains provided on a surface of the support
member, wherein the variation in density of the hard abrasive
grains among regions having a given area where said hard abrasive
grains are present is within .+-.50%.
5. The CMP conditioner according to any one of claims 1 to 4,
wherein said hard abrasive grains are diamond grains.
6. The CMP conditioner according to claim 5, wherein said diamond
grains have been brazed in a single layer to said support member,
formed of a metal and/or an alloy, with an alloy containing 0.5 to
20% by weight of at least one member selected from the group
consisting of titanium, chromium, and zirconium and having a
melting point of 650.degree. C. to 1,200.degree. C. to form a layer
of a carbide of a metal selected from the group consisting of
titanium, chromium, and zirconium at the interface between the
diamond grains and the alloy.
7. A method for arranging hard abrasive grains for use in a CMP
conditioner, comprising the steps of: positioning an arranging
member in a thin plate form, provided with a plurality of regularly
arranged through-holes, on an abrasive grain arrangement surface;
and placing a hard abrasive grain in each through-hole of the
arranging member.
8. The method according to claim 7, wherein the abrasive grain
arrangement surface is a surface of a support member for
constituting the CMP conditioner.
9. A method for arranging hard abrasive grains for use in a CMP
conditioner, comprising the steps of: holding a plurality of hard
abrasive grains, in a regularly arranged state, on a holding
member; and transferring the hard abrasive grains held on the
holding member onto the surface of a support member for
constituting the CMP conditioner.
10. The method according to claim 9, wherein said holding member
has first bonding means for holding the hard abrasive grains and
said support member has on its surface second bonding means which
is different from said first bonding means in properties.
11. A process for producing a CMP conditioner, comprising the steps
of: utilizing the method for arranging hard abrasive grains for use
in a CMP conditioner according to any one of claims 7 to 10 to
arrange the hard abrasive grains on the surface of the support
member; and then fixing the hard abrasive grains on the surface of
the support member.
12. A CMP conditioner comprising: a support member; and a plurality
of hard abrasive grains provided on the surface of the support
member, wherein said plurality of hard abrasive grains are arranged
on the surface of the support member regularly and so as for the
density of the hard abrasive grains to decrease from the inner side
of the support member toward the outer side of the support
member.
13. The CMP conditioner according to claim 12, wherein said hard
abrasive grains are arranged substantially radially from the center
of the support member.
14. A CMP conditioner comprising: a support member; and a plurality
of hard abrasive grains provided on a surface of said support
member, wherein regions, where said plurality of hard abrasive
grains are absent, are provided substantially radially on the
surface of the support member.
15. The CMP conditioner according to any one of claims 12 to 14,
wherein said hard abrasive grains are diamond grains.
16. The CMP conditioner according to claim 15, wherein said diamond
grains have been brazed in a single layer to said support member,
formed of a metal and/or an alloy, with an alloy containing 0.5 to
20% by weight of at least one member selected from the group
consisting of titanium, chromium, and zirconium and having a
melting point of 650.degree. C. to 1,200.degree. C. to form a layer
of a carbide of a metal selected from the group consisting of
titanium, chromium, and zirconium at the interface between the
diamond grains and the alloy.
17. The CMP conditioner according to claim 16, wherein said alloy
having a melting point of 650.degree. C to 1,200.degree. C. is a
nickel-base alloy.
18. A method for arranging hard abrasive grains for use in a CMP
conditioner, comprising the steps of: positioning an arranging
member in a thin plate form, provided with a plurality of
through-holes arranged regularly and so as for the density of the
through-holes to decrease from the inner side toward the outer side
of the arranging member, on an abrasive grain arrangement surface;
and placing a hard abrasive grain in each through-hole of the
arranging member.
19. A method for arranging hard abrasive grains for use in a CMP
conditioner, comprising the steps of: positioning an arranging
member in a thin plate form, in which regions free from a plurality
of through-holes are provided substantially radially, on an
abrasive grain arrangement surface; and placing a hard abrasive
grain in each through-hole of the arranging member.
20. The method according to claim 18 or 19, wherein the abrasive
grain arrangement surface is a surface of a support member for
constituting the CMP conditioner.
21. A method for arranging hard abrasive grains for use in a CMP
conditioner, comprising the steps of: holding a plurality of hard
abrasive grains, on a holding member, in such a state that the hard
abrasive grains are arranged regularly and so as for the density of
said hard abrasive grains to decrease from the inner side toward
the outer side of the holding member; and transferring the hard
abrasive grains held on the holding member onto the surface of a
support member for constituting the CMP conditioner.
22. A method for arranging hard abrasive grains for use in a CMP
conditioner, comprising the steps of: holding a plurality of hard
abrasive grains, on a holding member, in such a state that regions
free from said plurality of hard abrasive grains are provided
substantially radially; and transferring the hard abrasive grains
held on the holding member onto the surface of a support member for
constituting the CMP conditioner.
23. The method according to claim 21 or 22, wherein said holding
member has first bonding means for holding the hard abrasive grains
and said support member has on its surface second bonding means
which is different from said first bonding means in properties.
24. A process for producing a CMP conditioner, comprising the steps
of: utilizing the method for arranging hard abrasive grains for use
in a CMP conditioner according to any one of claims 18 to 23 to
arrange the hard abrasive grains on the surface of the support
member; and then fixing the hard abrasive grains on the surface of
the support member.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a CMP conditioner for
repairing loading of an polishing pad for a semiconductor substrate
and for removing materials which have caused loading of the
polishing pad, a method for arranging hard abrasive grains for use
in a CMP conditioner, and a process for producing a CMP
conditioner. The CMP conditioner is also called "CMP dresser" in
the art.
[0003] 2. Background Art
[0004] A polishing method called "CMP (chemical mechanical
polishing)" has been proposed for polishing wafers. In CMP,
chemical polishing action is superimposed on mechanical polishing
action to realize a combination of ensuring of satisfactory removal
rate with a defect-free polished object, and CMP has widely been
used in the step of finish polishing a silicon wafer.
[0005] Further, in recent years, an increase in integration density
of devices has led to the necessity of polishing the surface of a
wafer or the surface of a semiconductor substrate, comprising an
electric conductor/dielectric layer formed on a surface of a wafer,
in a predetermined stage for the production of an integrated
circuit. The semiconductor substrate is polished to remove surface
defects such as high projections, scratches, and roughness. In
general, this step is carried out during the formation of various
elements and integrated circuits on a wafer. In this polishing
step, as with the step of finish polishing a silicon wafer, a
combination of a removal rate requirement with a defect-free
requirement should be met. The introduction of chemical slurry can
realize chemical and mechanical flattening of the surface of a
semiconductor with higher polishing/removing speed and a
defect-free state.
[0006] An example of the CMP step (process) is shown in FIG. 8. In
this example, a chemical slurry 101 prepared by suspending, for
example, silica particles having a diameter of about 5 to 300 nm in
a solution of an alkali, such as caustic soda, ammonia, or amine,
to prepare a slurry having a pH value of about 9 to 12 and an
polishing pad 102 formed of a polyurethane resin or the like are
used. At the time of polishing, a semiconductor substrate 103 is
abutted against the polishing pad 102 by applying a suitable
pressure while allowing the chemical slurry 101 to flow and spread
on the polishing pad 102, and the semiconductor substrate 103 and
the polishing pad 102 are rotated relatively to each other as
indicated by arrows in the drawing.
[0007] The polishing pad 102 is conditioned (dressed) with a CMP
conditioner while allowing water or the chemical slurry 101 to flow
on the polishing pad 102 to repair loading of the polishing pad 102
and to remove materials which have caused the loading of the
polishing pad 102. The conditioning with a CMP conditioner is
carried out, either after the completion of polishing of the
semiconductor substrate 103, by abutting the CMP conditioner
against the polishing pad 102, or, simultaneously with the start of
polishing of the semiconductor substrate 103, by abutting the CMP
conditioner against the polishing pad 102 at its position different
from the position where the semiconductor substrate 103 is abutted
against the polishing pad 102.
[0008] In the CMP conditioner used in the conventional conditioning
(brushing) of the polishing pad, as shown in FIG. 9, diamond grains
202 as hard abrasive grains are evenly distributed, for example, by
manually spreading the diamond grains 202 over the surface of a
disk-shaped support member 201 and then fixing the diamond grains
202 onto the support member 201.
[0009] In this case, however, whatever the diamond grains 202 are
spread carefully, the distribution of the diamond grains 202 is
disadvantageously such that the diamond grains 202 are sparsely
present in some portion and are densely present in another portion.
When this conditioner with uneven distribution of the diamond
grains 202 is used, abrasive grains contained in the chemical
slurry are disadvantageously likely to aggregate in a portion where
the diamond grains 202 are densely present. This poses a severe
problem that the aggregate of the abrasive grains is adhered to the
polishing pad (102 in FIG. 8), and, consequently, microscratches
the semiconductor substrate (103 in FIG. 8). Further, uneven
distribution of the diamond grains 202 is causative of a difference
between conditioners and hinders the development of stable
conditioner properties.
[0010] Further, in the conventional CMP conditioner, since the
slurry cannot be smoothly escaped, significant microscratching
occurs. In order to improve the escape of the slurry, as shown in
FIG. 14, for example, escape grooves 203 for escaping the chemical
slurry 101 are provided in the support member 201. In this case, at
the time of polishing, the chemical slurry 101 is escaped through
the escape grooves 203. The formation of the escape grooves 203 in
the support member 201, however, has a fear of adversely affecting
CMP conditioner properties. Further, the formation of the escape
grooves requires labor and a lot of time. This incurs increased
cost.
SUMMARY OF THE INVENTION
[0011] In view of the above, the present invention has been made,
and, in the first aspect of the present invention, an object is to
suppress microscratching on the surface of a semiconductor
substrate and, at the same time, to provide stable CMP conditioner
properties.
[0012] According to the first aspect of the present invention,
there is provided a CMP conditioner comprising: a support member;
and a plurality of hard abrasive grains provided on a surface of
the support member, characterized in that said plurality of hard
abrasive grains are regularly arranged on the surface of the
support member.
[0013] Another characteristic feature of the CMP conditioner
according to the first aspect of the present invention is that said
hard abrasive grains are arranged at respective lattice points of a
unit lattice formed of a square on the surface of the support
member.
[0014] A further characteristic feature of the CMP conditioner
according to the first aspect of the present invention is that said
hard abrasive grains are arranged at respective lattice points of a
unit lattice formed of a regular triangle on the surface of the
support member.
[0015] Another CMP conditioner according to the first aspect of the
present invention comprises: a support member; and a plurality of
hard abrasive grains provided on a surface of the support member,
characterized in that the variation in density of the hard abrasive
grains among regions having a given area where said hard abrasive
grains are present is within .+-.50%.
[0016] Another characteristic feature of the CMP conditioner
according to the first aspect of the present invention is that said
hard abrasive grains are diamond grains.
[0017] A further characteristic feature of the CMP conditioner
according to the first aspect of the present invention is that said
diamond grains have been brazed in a single layer to said support
member, formed of a metal and/or an alloy, with an alloy containing
0.5 to 20% by weight of at least one member selected from the group
consisting of titanium, chromium, and zirconium and having a
melting point of 650.degree. C. to 1,200.degree. C. to form a layer
of a carbide of a metal selected from the group consisting of
titanium, chromium, and zirconium at the interface between the
diamond grains and the alloy.
[0018] A method for arranging hard abrasive grains for use in the
CMP conditioner according to the first aspect of the present
invention is characterized by comprising the steps of: positioning
an arranging member in a thin plate form, provided with a plurality
of regularly arranged through-holes, on an abrasive grain
arrangement surface; and placing a hard abrasive grain in each
through-hole of the arranging member.
[0019] Another characteristic feature of the method for arranging
hard abrasive grains for use in the CMP conditioner according to
the first aspect of the present invention is that the abrasive
grain arrangement surface is a surface of a support member for
constituting the CMP conditioner.
[0020] Another method for arranging hard abrasive grains for use in
the another CMP conditioner according to the first aspect of the
present invention is characterized by comprising the steps of:
holding a plurality of hard abrasive grains, in a regularly
arranged state, on a holding member; and transferring the hard
abrasive grains held on the holding member onto the surface of a
support member for constituting the CMP conditioner.
[0021] Another characteristic feature of the method for arranging
hard abrasive grains for use in the another CMP conditioner
according to the first aspect of the present invention is that said
holding member has first bonding means for holding the hard
abrasive grains and said support member has on its surface second
bonding means which is different from said first bonding means in
properties.
[0022] A process for producing the CMP conditioner according to the
first aspect of the present invention is characterized by
comprising the steps of: utilizing the method for arranging hard
abrasive grains for use in the above CMP conditioner to arrange the
hard abrasive grains on the surface of the support member; and then
fixing the hard abrasive grains on the surface of the support
member.
[0023] According to the first aspect of the present invention as
described above, the problem of uneven distribution of hard
abrasive grains can be solved. Therefore, the CMP conditioner does
not lead to a fear that abrasive grains contained in the slurry
aggregate in the dresser in its portion where hard abrasive grains
are densely present.
[0024] In the second aspect of the present invention, an object is
to provide stable CMP conditioner properties and, at the same time,
to enable the escape of the slurry or the like at the time of
polishing without forming escape grooves or the like, and to reduce
microscratching.
[0025] According to the second aspect of the present invention,
there is provided a CMP conditioner comprising: a support member;
and a plurality of hard abrasive grains provided on the surface of
the support member, characterized in that said plurality of hard
abrasive grains are arranged on the surface of the support member
regularly and so as for the density of the hard abrasive grains to
decrease from the inner side of the support member toward the outer
side of the support member.
[0026] Another CMP conditioner according to the second aspect of
the present invention comprises: a support member; and a plurality
of hard abrasive grains provided on a surface of said support
member, characterized in that regions, where said plurality of hard
abrasive grains are absent, are provided substantially radially on
the surface of the support member.
[0027] A method for arranging hard abrasive grains for use in the
CMP conditioner according to the second aspect of the present
invention is characterized by comprising the steps of: positioning
an arranging member in a thin plate form, provided with a plurality
of through-holes arranged regularly and so as for the density of
the through-holes to decrease from the inner side toward the outer
side of the arranging member, on an abrasive grain arrangement
surface; and placing a hard abrasive grain in each through-hole of
the arranging member.
[0028] Another method for arranging hard abrasive grains for use in
the CMP conditioner according to the second aspect of the present
invention is characterized by comprising the steps of: positioning
an arranging member in a thin plate form, in which regions free
from a plurality of through-holes are provided substantially
radially, on an abrasive grain arrangement surface; and placing a
hard abrasive grain in each through-hole of the arranging
member.
[0029] Still another method for arranging hard abrasive grains for
use in the CMP conditioner according to the second aspect of the
present invention is characterized by comprising the steps of:
holding a plurality of hard abrasive grains, on a holding member,
in such a state that the hard abrasive grains are arranged
regularly and so as for the density of said hard abrasive grains to
decrease from the inner side toward the outer side of the holding
member; and transferring the hard abrasive grains held on the
holding member onto the surface of a support member for
constituting the CMP conditioner.
[0030] A further method for arranging hard abrasive grains for use
in the CMP conditioner according to the second aspect of the
present invention is characterized by comprising the steps of:
holding a plurality of hard abrasive grains, on a holding member,
in such a state that regions free from said plurality of hard
abrasive grains are provided substantially radially; and
transferring the hard abrasive grains held on the holding member
onto the surface of a support member for constituting the CMP
conditioner.
[0031] A process for producing the CMP conditioner according to the
second aspect of the present invention is characterized by
comprising the steps of: utilizing the method for arranging hard
abrasive grains for use in the above CMP conditioner to arrange the
hard abrasive grains on the surface of the support member; and then
fixing the hard abrasive grains on the surface of the support
member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is an explanatory view of a CMP conditioner according
to the first aspect of the present invention;
[0033] FIG. 2 is a diagram showing one embodiment of the
arrangement of diamond grains 2 according to the first aspect of
the present invention;
[0034] FIG. 3 is a diagram showing one embodiment of the
arrangement of diamond grains 2 according to the first aspect of
the present invention;
[0035] FIG. 4 is a diagram illustrating a first method for
arranging diamond grains 2 in the first aspect of the present
invention;
[0036] FIG. 5 is a diagram illustrating an arranging plate 5
according to the first aspect of the present invention;
[0037] FIGS. 6A and 6B are diagrams illustrating a second method
for arranging diamond grains 2 in the first aspect of the present
invention, wherein FIG. 6A shows spreading of diamond grains 2 over
the arranging plate 7 and FIG. 6B shows such a state that a
pressure-sensitive adhesive sheet 10 has been separated from the
arranging plate 7;
[0038] FIG. 7 is a diagram illustrating the second method for
arranging diamond grains 2 in the first aspect of the present
invention;
[0039] FIG. 8 is a diagram illustrating a CMP step;
[0040] FIG. 9 is a diagram illustrating a conventional CMP
conditioner;
[0041] FIG. 10 is an explanatory view of a CMP conditioner
according to the second aspect of the present invention;
[0042] FIG. 11 is a diagram showing one embodiment of the
arrangement of diamond grains 12 according to the second aspect of
the present invention;
[0043] FIG. 12 is a diagram showing one embodiment of the
arrangement of diamond grains 12 according to the second aspect of
the present invention;
[0044] FIG. 13 is a diagram illustrating an arranging plate 15
according to the second aspect of the present invention; and
[0045] FIG. 14 is a typical diagram showing a CMP conditioner
provided with escape grooves 203.
DETAILED DESCRIPTION OF THE INVENTION
[0046] CMP Conditioner According to First Aspect of the
Invention
[0047] Embodiments of the CMP conditioner for an polishing pad for
a semiconductor substrate, the method for arranging hard abrasive
grains for use in a CMP conditioner for an polishing pad for a
semiconductor substrate, and the process for producing a CMP
conditioner according to the first aspect of the present invention
will be described with reference to the accompanying drawings.
[0048] The CMP conditioner will be first described in conjunction
with FIG. 1. As shown in FIG. 1, diamond grains 2 as hard abrasive
grains are fixed onto a surface of a disk-shaped support member 1
formed of a stainless steel or the like. The appearance of the CMP
conditioner shown in FIG. 1 is a mere example. Diamond grains 2 may
not be always present over the whole surface of the support member
1. Escape grooves for escaping a chemical slurry may be formed, for
example, on the surface of the support member 1.
[0049] FIGS. 2 and 3 are enlarged views of the surface of the
support member 1, illustrating the arrangement of diamond grains 2.
In FIG. 2, diamond grains 2 are arranged in a check pattern. A
diamond grain 2 is placed on each lattice point of a square unit
lattice A on the surface of the support member 1. More
specifically, it is assumed that, as indicated by alternate long
and short dash lines in FIG. 2, a first group of straight lines
L.sub.1, which are arranged parallel to one another at given
intervals, and a second group of straight lines L.sub.2 (horizontal
lines in FIG. 2), which are arranged parallel to one another at
given intervals and intersect the first group of straight lines
L.sub.1 at 90 degrees, are provided. Diamond grains 2 are placed on
points of intersection of the first group of straight lines L.sub.1
and the second group of straight lines L.sub.2.
[0050] In FIG. 3, diamond grains 2 are arranged in a honeycomb
form. On the surface of the support member 1, a diamond grain 2 is
placed on each lattice point of a unit lattice B of an equilateral
triangle. More specifically, it is assumed that, as indicated by
alternate long and short dash lines in FIG. 3, a third group of
straight lines L.sub.3, which are arranged parallel to one another
at given intervals, and a fourth group of straight lines L.sub.4,
which are arranged parallel to one another at given intervals and
intersect the third group of straight lines L.sub.3 at 120 degrees,
are provided. Diamond grains 2 are placed on points of intersection
of the third group of straight lines L.sub.3 and the fourth group
of straight lines L.sub.4.
[0051] In the arrangement shown in FIG. 2, the distance from a
certain diamond grain 2 to each of four diamond grains 2 adjacent
vertically and horizontally to the certain diamond grain 2 is r,
and the distance of the certain diamond grain 2 to each of four
diamond grains adjacent diagonally to the certain diamond grain is
({square root}{square root over (2)})r.
[0052] On the other hand, in the arrangement shown in FIG. 3, all
of six adjacent diamond grains 2 are equidistant from a certain
diamond grain 2, that is, the distance of a certain diamond grain 2
to each of the six adjacent diamond grains 2 is r. Therefore, in
the strict sense of the word, the distribution of diamond grains 2
in the arrangement shown in FIG. 3 is more homogeneous than the
distribution of diamond grains 2 in the arrangement shown in FIG.
2. Therefore, the arrangement shown in FIG. 3 can provide superior
CMP conditioner properties.
[0053] The method for arranging diamond grains 2 according to the
second aspect of the present invention will be described with
reference to FIGS. 4 to 7. In embodiments shown in FIGS. 4 to 7,
diamond grains 2 are arranged by the following two methods.
[0054] In the first method, as shown in FIG. 4, an adhesive 4 is
previously coated onto a surface of a support member 1 provided
with a brazing material 3. An arranging plate 5 is mounted on the
support member 1 in its surface coated with the adhesive 4 to
perform masking.
[0055] As shown in FIG. 5, through-holes 6 for arranging diamond
grains 2 are provided in the arranging plate 5. Specifically, in
the arranging plate 5, through-holes 6 are arranged in a form
identical to the arrangement shown in FIG. 2 or 3. The relationship
between the diameter X of the through-holes 6 and the size D of the
diamond grains 2 satisfies a requirement represented by formula
1.0D<X<2.0D. Satisfying this relationship can prevent a
plurality of diamond grains 2 from simultaneously entering one
through-hole 6. A scattering preventive wall 5a is provided on the
circumference of the arranging plate 5.
[0056] As shown in FIG. 4, in such a state that the arranging plate
5 is mounted on the surface of the support member 1, diamond grains
2 are spread over the arranging plate 5. At that time, for example,
suitable vibration is applied to the arranging plate 5 so that the
diamond grains 2 enter all the through-holes 6. When the diamond
grains 2 have entered all the through-holes 6, excess diamond
grains 2 present on the arranging plate 5 are removed, for example,
by a brush. Thereafter, the arranging plate 5 is removed from the
surface of the support member 1 to leave the diamond grains 2
arranged on the surface of the support member 1 as shown in FIG. 2
or 3.
[0057] After the diamond grains 2 have been arranged on the surface
of the support member 1 by the above method, brazing in a single
layer is carried out to fix the diamond grains 2. In this brazing,
the adhesive 4 coated onto the surface of the support member 1 is
sublimated upon heating of the brazing material 3 and thus does not
stay on the surface of the support-member 1.
[0058] In the first method, a mesh woven out of wire may be used
instead of the arranging plate 5. Specifically, individual openings
of the mesh are used as the through-holes 6 referred to in the
arranging plate 5, and diamond grains 2 are put into the openings
to arrange the diamond grains on the-surface of the support member
1.
[0059] In the second method, unlike the first method wherein the
diamond grains 2 are arranged directly on the surface of the
support member 1, diamond grains are once arranged on a holding
member, such as a pressure-sensitive adhesive sheet, and the
arranged diamond grains are then transferred onto the surface of
the support member 1.
[0060] In the second method, as shown in FIG. 6A, concaves 8 for
arranging diamond grains 2 are provided in an arranging plate 7 so
as to conform to the arrangement shown in FIG. 2 or 3. In the
concaves 8 in the second method, as with the through-holes 6 in the
first method, the relationship between the diameter X of concaves 8
and the size D of the diamond grains 2 satisfies a requirement
represented by formula 1.0D <X<2.0D.
[0061] Diamond grains 2 are spread over the arranging plate 7. At
that time, as described above in connection with the first method,
for example, suitable vibration is applied to the arranging plate 7
so that the diamond grains 2 enter all the concaves 8. When the
diamond grains 2 have entered all the concaves 8, excess diamond
grains 2 present on the arranging plate 7 are removed, for example,
by a brush 9.
[0062] A pressure-sensitive adhesive sheet 10 is then applied onto
the surface of the arranging plate 7 on its concave 8 side. Next,
as shown in FIG. 6B, the pressure-sensitive adhesive sheet 10 is
separated, for example, by turning the arranging plate 7 upside
down, whereby the diamond grains 2 are arranged and held on the
pressure-sensitive adhesive sheet 10.
[0063] Thereafter, the pressure-sensitive adhesive sheet 10 with
the diamond grains 2 held thereon is applied onto the surface of
the support member 1 coated with an adhesive 4 so that the
diamond-holding pressure-sensitive adhesive surface of the
pressure-sensitive adhesive sheet 10 comes into contact with the
adhesive 4. Therefore, as shown in FIG. 7, one end of each diamond
grain 2 is supported on the pressure-sensitive adhesive sheet 10
side, and the other end of each diamond grain 2 is supported on the
surface side of the support member 1. Thereafter, only the
pressure-sensitive adhesive sheet 10 is removed while allowing the
diamond grains 2 to stay on the surface side of the support member
1. Thus, the diamond grains 2 can be arranged on the surface of the
support member 1.
[0064] The removal of only the pressure-sensitive adhesive sheet 10
can be achieved, for example, by providing a difference in
solubility between the adhesive in the pressure-sensitive adhesive
sheet 10 and the adhesive 4 on the support member 1 side. In this
case, in the state shown in FIG. 7, when the assembly is placed in
an environment where the adhesive in the pressure-sensitive
adhesive sheet 10 is dissolved, while maintaining the holding power
of the adhesive 4 on the support member 1 side, only the adhesive
in the pressure-sensitive adhesive sheet 10 can be dissolved to
remove only the pressure-sensitive adhesive sheet 10.
[0065] After the diamond grains 2 have been arranged on the surface
of the support member 1 by the above method, brazing in a single
layer is carried out to fix the diamond grains 2. In this brazing,
the adhesive 4 coated onto the surface of the support member 1 is
sublimated upon heating of the brazing material 3 and thus does not
stay on the surface of the support member 1.
[0066] In the second method, concaves 8 are provided in the
arranging plate 7. Alternatively, through-holes may be provided
instead of the concaves 8. In this case, when the support member 1
shown in FIG. 4 is changed to a pressure-sensitive adhesive sheet
10, diamond grains can be arranged on the pressure-sensitive
adhesive sheet 10. Therefore, the diamond grains arranged on the
surface of the pressure-sensitive adhesive sheet 10 can be then
transferred onto the surface of the support member 1.
[0067] According to the above embodiments of the present invention,
since the diamond grains are regularly arranged, the distribution
of the diamond grains is even. The use of the CMP conditioners
according to the above embodiments does not cause such an
unfavorable phenomenon that abrasive grains contained in a slurry
aggregate in a portion where diamond grains are densely present.
Therefore, microscratching of the surface of the semiconductor
substrate can be minimized. Further, since the difference in
properties among CMP conditioners can be eliminated, stable CMP
conditioner properties can be provided.
[0068] In the above embodiments, diamond grains have been arranged
as shown in FIGS. 2 and 3. However, the arrangement of diamond
grains is not limited to that shown in FIGS. 2 and 3, and
arrangements other than those shown in FIGS. 2 and 3 may be adopted
so far as the distribution of diamond grains is even. In this case,
for example, a certain limitation on the density of diamond grains
is provided. For example, on the surface of the support member 1,
in areas where diamond grains 2 are present, a variation in density
of diamond grains 2 among regions having a given area where several
to several tens of diamond grains 2 on average, for example, 20
diamond grains 2, are present, is limited to within .+-.50%.
[0069] In the above embodiments of the present invention, diamond
grains 2 have been used as the hard abrasive grains. Alternatively,
other materials, for example, cubic boron nitride, boron carbide,
silicon carbide, or aluminum oxide may be used as the hard abrasive
grains.
[0070] In addition to brazing, for example, electro deposition of
nickel may be used for fixation of the diamond grains 2 onto the
support member 1.
[0071] Fixation of the diamond grains by brazing will be described
as a suitable one example of the method for the fixation of the
diamond grains. An alloy containing 0.5 to 20% by weight of at
least one member selected from titanium, chromium, and zirconium
and having a melting point of 650.degree. C. to 1,200 .degree. C.
is preferably used as a brazing material. In this case, a carbide
layer of this metal is formed at the interface between the diamond
grains and the brazing alloy. The reason why the content of at
least one member selected from titanium, chromium, and zirconium
contained in the alloy as the brazing material is preferably 0.5 to
20% by weight is as follows. When the content of the metal is less
than 0.5% by weight, the carbide layer of the metal is not formed
at the interface between the diamond and the brazing alloy. On the
other hand, when the content of the metal is 20% by weight, a
carbide layer having satisfactory bonding strength can be
formed.
[0072] The reason why the melting point of the brazing alloy is
preferably 650.degree. C. to 1,200.degree. C. is that, when the
brazing temperature is below 650.degree. C., bonding strength
cannot be ensured while, when the brazing temperature is above
1,200.degree. C., the diamond is disadvantageously
deteriorated.
[0073] The thickness of the brazing alloy is preferably 0.2 to 1.5
times that of the diamond grains. When the thickness of the brazing
alloy is below the above lower limit value, the bonding strength
between the diamond and the brazing alloy is lowered. On the other
hand, when the thickness of the brazing alloy is above the upper
limit of the above-defined range, the separation between the
brazing material and the support member is likely to take
place.
[0074] The diameter of the diamond grains is preferably in the
range of 50 .mu.m to 300 .mu.m. Fine diamond grains having a
diameter of less than 50 .mu.m do not provide satisfactory
polishing rate, are likely to aggregate, and are likely to come off
from the support member. On the other hand, coarse diamond grains
having a diameter of more than 300 .mu.m cause large stress
concentration at the time of polishing and are likely to come off
from the support member.
[0075] As described above, according to the first embodiment of the
present invention, the use of the CMP conditioner does not have any
fear of abrasive grains contained in the slurry being aggregated in
CMP conditioner in its portion where hard abrasive grains are
densely present. As a result, microscratching of the surface of the
semiconductor substrate can be minimized. Further, the difference
in properties among CMP conditioners can be eliminated, and, thus,
stable CMP conditioner properties can be achieved. Therefore,
stable CMP mass production process can be realized.
[0076] CMP Conditioner According to Second Aspect of the
Invention
[0077] Embodiments of the CMP conditioner for an polishing pad for
a semiconductor substrate according to the second aspect of the
present invention will be explained with reference to the
accompanying drawings. For the method for arranging hard abrasive
grains used in the CMP conditioner for an polishing pad for a
semiconductor substrate, and the production of the CMP conditioner
in this aspect of the present invention may be the same as the
first and second methods in the first aspect of the present
invention, except that an arranging plate 15 shown in FIG. 13 is
used instead of the arranging plate 5 shown in FIG. 5. Therefore,
except for this point, the above description in connection with the
first aspect of the present invention is applied to the second
aspect of the present invention.
[0078] The CMP conditioner according to the second aspect of the
present invention will be described with reference to FIG. 10. As
shown in FIG. 10, diamond grains 12 have been fixed as hard
abrasive grains onto a surface of a disk-shaped support member 11
formed of a stainless steel or the like.
[0079] FIGS. 11 and 12 are schematic diagrams showing the
arrangement of diamond grains 12 on the surface of the support
member 11. In the embodiment shown in FIG. 11, assuming that a
plurality of straight lines (alternate long and short dash lines L)
extended radially from the center of the disk-shaped support member
11 are provided, diamond grains 12 are provided on these straight
lines. In this CMP conditioner, diamond grains 12 are arranged so
that the density of diamond grains 12 decreases from the inner side
of the support member 11 toward the outer side of the support
member 11. Regions, where the diamond grains 12 are absent, are
ensured radially on the surface of the support member 11.
[0080] On the other hand, in the embodiment shown in FIG. 12,
assuming that a plurality of curved lines (alternate long and short
dash lines L) extended radially from the center of the disk-shaped
support member 11 are provided, diamond grains 12 are provided on
these curved lines. In this CMP conditioner, diamond grains 12 are
arranged so that the density of diamond grains 12 decreases from
the inner side of the support member 11 toward the outer side of
the support member 11. Regions, where the diamond grains 12 are
absent, are ensured radially on the surface of the support member
11. The term "substantially radially" referred to in the present
invention is applied to the embodiment shown in FIG. 11 wherein the
diamond grains are arranged radially in a straight line form, as
well as in the embodiment shown in FIG. 12 wherein the diamond
grains 12 are provided radially in a curved line form.
[0081] The size of actual diamond grains 12 is much smaller than
that of the support member 11. In FIG. 10 and FIGS. 11 and 12 which
will be described later, however, diamond grains 12 are shown in a
larger size than the size of actual diamond grains for simplified
explanation. Further, the number of straight lines and the number
of curved lines are actually provided radially in a denser state.
In FIGS. 11 and 12, however, the number of straight lines and the
number of curved lines are shown in a simplified form.
[0082] In the second aspect of the present invention, the
arrangement of the diamond grains 12 and the production of the CMP
conditioner may be carried out as in the first and second methods
described above in connection with the first aspect of the present
invention, except that an arranging plate 15 shown in FIG. 13 is
used instead of the arranging plate 5 shown in FIG. 5. As shown in
FIG. 13, through-holes 16 for arranging diamond grains 12 are
provided in the arranging plate 15. Specifically, in FIG. 13, as
with the arrangement shown in FIGS. 11 and 12, through-holes 16 are
arranged in the arranging plate 15. The relationship between the
diameter X of the through-holes 16 and the size D of the diamond
grains 12 satisfies a requirement represented by formula
1.0D<X<2.0D. Satisfying this relationship can prevent a
plurality of diamond grains 12 from simultaneously entering one
through-hole 16. A scattering preventive wall 15a is provided on
the circumference of the arranging plate 15.
[0083] As described above, in this embodiment, since the diamond
grains 12 are regularly arranged, the difference in properties
among CMP conditioners can be eliminated. Therefore, stable CMP
conditioner properties can be realized. Further, in this
embodiment, the diamond grains 12 are arranged substantially
radially from the center of the support member 11 so that the
density of the diamond grains decreases from the inner side of the
support member 11 toward the outer side of the support member 11.
Furthermore, regions, where the diamond grains 12 are absent, are
ensured radially. By virtue of the adoption of this construction,
at the time of polishing, the slurry can be escaped toward the
outer side of the support member 11, contributing to reduced
microscratching. Further, since the need to apply special working,
to the support member 11, for escaping the slurry can be
eliminated, labor and time and cost for working can be reduced.
[0084] As described above, according to the second aspect of the
present invention, the difference in properties. among CMP
conditioners is eliminated, and stable CMP conditioner properties
can be provided. Therefore, a stable CMP mass-production process
can be realized. Further, since the slurry can be escaped at the
time of polishing, microscratching can be reduced. Furthermore,
since there is no need to apply special working, to the support
member, for escaping the slurry, labor and time and cost for
working can be reduced.
EXAMPLES
[0085] The following examples further illustrate but do not limit
the first aspect of the present invention.
[0086] Diamond grains having a diameter of 150 to 210 .mu.m were
provided. A ferrite stainless steel support member was also
provided. In order to fix the diamond grains to the support member,
brazing in a single layer was carried out with a brazing metal of
Ag--Cu--3Zr (melting point: 800.degree. C.) by holding the assembly
in a vacuum of 10.sup.-5 Torr at a brazing temperature of
850.degree. C. for 30 min. Ten CMP conditioners were prepared for
each of three types, type A (a conventional type where diamond
grains had been manually spread) , type B (arrangement in a check
form shown in FIG. 2), and type C (arrangement in a honeycomb form
shown in FIG. 3).
[0087] For each CMP conditioner, an experiment on polishing was
carried out for ten semiconductor wafers with a TEOS film.
Specifically, for each of types A, B, and C, polishing was carried
out for 100 wafers. Dressing was carried out for 2 min once for
each one polishing.
[0088] Thereafter, for each type, one polished wafer was extracted
from every 10 polished wafers in 100 polished wafers. That is, for
each type, 10 polished wafers in total were extracted from the 100
polished wafers. For the 10 extracted polished wafers for each
type, the number of microscratches was counted. As a result, when
the number of microscratches, in the case where the CMP conditioner
(dresser) of type A was used, was presumed to be 100, the relative
value of the number of microscratches in the case where the CMP
conditioner (dresser) of type B was used and the relative value of
the number of microscratches in the case where the CMP conditioner
(dresser) of type C was used, were 26 and 17, respectively.
[0089] These results show that, in the CMP conditioners of types B
and C, as compared with the conventional CMP conditioner of type A,
the number of microscratches on the surface of the wafer can be
significantly reduced. Further, the difference in CMP conditioner
properties among CMP conditioners is so small that a stable CMP
mass-production process can be realized.
* * * * *