U.S. patent application number 11/946135 was filed with the patent office on 2008-06-05 for cmp conditioner.
This patent application is currently assigned to Mitsubishi Materials Corporation. Invention is credited to Kasumi Chida, Naoki Rikita.
Application Number | 20080132153 11/946135 |
Document ID | / |
Family ID | 39046715 |
Filed Date | 2008-06-05 |
United States Patent
Application |
20080132153 |
Kind Code |
A1 |
Rikita; Naoki ; et
al. |
June 5, 2008 |
CMP CONDITIONER
Abstract
To provide a CMP conditioner that prevents dissolution of metals
in slurry, without the chipping of the abrasive grains and/or
decreasing the cutting performance. The CMP apparatus has a
polishing pad that faces and contacts conditioning surface of the
conditioner body. On this conditioning surface, abrasive grains are
distributed and fixed to form abrasive grain layer, thus forming
the CMP conditioner. The conditioner body is made of ceramics, the
abrasive grains in the abrasive grain layer are held by binding
phase made of low temperature co-fired ceramics.
Inventors: |
Rikita; Naoki; (Saitama-shi,
JP) ; Chida; Kasumi; (Saitama-shi, JP) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770, Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
Mitsubishi Materials
Corporation
Chiyoda-ku
JP
|
Family ID: |
39046715 |
Appl. No.: |
11/946135 |
Filed: |
November 28, 2007 |
Current U.S.
Class: |
451/56 ;
451/443 |
Current CPC
Class: |
B24B 53/12 20130101;
B24B 53/017 20130101 |
Class at
Publication: |
451/56 ;
451/443 |
International
Class: |
B24B 53/02 20060101
B24B053/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2006 |
JP |
2006-321542 |
Claims
1. A CMP conditioner comprising: a conditioner body facing and
contacting a polishing pad of a CMP apparatus, and an abrasive
grain layer formed on a conditioning surface of the conditioning
body, wherein abrasive grains are distributed and adhered on the
abrasive grain layer, wherein the conditioner body is made of
ceramics and wherein a binding phase holding the abrasive grains in
the abrasive grain layer is made of low temperature co-fired
ceramics.
2. The CMP conditioner according to claim 1, wherein the
conditioner body is made of low temperature co-fired ceramics.
3. The CMP conditioner according to claim 1, wherein the low
temperature co-fired ceramics is MgO--SiO.sub.2 ceramics.
4. The CMP conditioner according to claim 1, further comprising a
chassis made of resin supporting sections other than the
conditioning surface of the conditioner body.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 to Japanese Patent Application No. 2006-321542, filed
Nov. 29, 2006. The contents of which are incorporated herein by
reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a CMP conditioner for
conditioning the polishing pad of a CMP (Chemical Mechanical
Polishing) apparatus that polishes semiconductor wafers and the
like.
DESCRIPTION OF RELATED ART
[0003] Various kinds of CMP conditioners in which abrasive grains
are fixed by metal plating binding phase of Ni and the like, on a
base metal plate, such as stainless steel have been reported. When
highly corrosive strong acid or strong alkaline slurry is used in a
CMP apparatus, the binding phase metal is dissolved, it become
undesirable to polish semiconductor wafers in such slurry with
dissolved metals. To avoid this problem, for example, Japanese
Patent No. 3527448 and Japanese Patent application Publication No.
2005-288685 disclose a CMP conditioner in which ceramics is
employed as the binding phase. which ceramics is employed as the
binding phase.
[0004] In the CMP conditioner disclosed in Japanese Patent No.
527448 and Japanese Patent application Publication No. 2005-288685
the ceramics binding phase is sintered for adhesion of abrasive
grains at the high temperature of 1200.degree. C. At such a high
temperature, for example, if the abrasive grains are diamond
super-abrasive grains, surfaces of the super-abrasive grains became
carbonized and blackened by the heat and chipping tends to occur.
On the other hand, to prevent the surfaces from such carbonation by
the heat, if the surfaces of the diamond super-abrasive grains are
coated as disclosed in Japanese Patent No. 527448 and Japanese
Patent application Publication No. 2005-288685, the cutting
performance of the polishing pad by such super-abrasive grains
became poor, which results in decrease of the pad polishing
rate.
SUMMARY OF THE INVENTION
[0005] With such background, this invention aims to provide a CMP
conditioner which restricts metal dissolution in the slurry,
without causing the chipping of the abrasive grains and/or
decreasing the cutting performance.
[0006] To overcome the above problems and accomplish the above
objective, this invention features a CMP conditioner having a
conditioner body, facing and in contact with the polishing pad of
the CMP apparatus; the CMP conditioner having an abrasive grain
layer formed on the conditioning surface of the conditioning body;
the abrasive grains distributed and fixed on the abrasive grain
layer. The above mentioned conditioner body is made of ceramics,
and the binding phase holding and fixing the abrasive grains in the
abrasive grain layer is made of low temperature co-fired ceramics
(LTCC).
[0007] The abrasive grains in the CMP conditioner are held in the
binding phase, which is made of low temperature co-fired ceramics;
these low temperature co-fired ceramics are known to compose
semiconductor substrates that can be sintered at relatively low
temperatures of 1000.degree. C. or below. Therefore even the
diamond super-abrasive grains need no surface coating, as the
carbonization and/or chipping by the sintering is prevented. In
addition, the abrasive grain layer holding the abrasive grains is
formed on the binding phase; this layer and the conditioning
surface of the conditioner body are made of the same ceramics. Thus
the CMP conditioner with the above structure can highly restrict
metal dissolution in strong acid or strong alkaline slurry.
[0008] Although it is possible to use pre-sintered ceramics for the
ceramics composing the conditioner body, if the body is made of the
low temperature co-fired ceramics, and the binding phase uses the
same low temperature co-fired ceramics, the conditioner body can be
sintered integrally with the binding phase. An example of the low
temperature co-fired ceramics that can be used to compose the
binding phase and/or the conditioner body is MgO--SiO.sub.2
ceramics. Preferably, spark plasma sintering (SPS) should be used
for sintering. Since it is difficult to make holes for screws in
the ceramics conditioner body to attach the CMP conditioner to the
CMP apparatus, it is preferable that sections of the conditioner
body are supported by a chassis made of resin, except for the
conditioning surface.
[0009] The CMP conditioner of this invention can prevent metal
dissolution in slurry without causing the chipping of the abrasive
grains and/or decreasing the cutting performance. Thus, it is
possible to prevent, with reliability, semiconductor wafers from
becoming contaminated by dissolved metals, and/or defects due to
scratches, etc., from the abrasive grains in the CMP apparatus;
thereby the polishing pad is in reliable condition, allowing
efficient polishing of the semiconductor wafers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a sectional view showing the CMP conditioner
according to an embodiment of the invention.
[0011] FIG. 2 is a sectional view showing an example of conditioner
material sintered at low temperature during the fabrication of the
CMP conditioner shown in FIG. 1.
[0012] FIG. 3 is a sectional view showing another example of
conditioner material sintered at low temperature during the
fabrication of the CMP conditioner shown in FIG. 1.
[0013] FIG. 4 is a sectional view showing still another example of
conditioner material sintered at low temperature during the
fabrication of the CMP conditioner shown in FIG. 1.
[0014] FIG. 5 is a sectional view showing yet another example of
conditioner material sintered at low temperature during the
fabrication of the CMP conditioner shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0015] FIG. 1 is a sectional view showing the CMP conditioner
according to an embodiment of the invention. The CMP conditioner of
this example has a disc shaped conditioner body 1. One of the
surfaces is a conditioning surface 2, that faces and contacts the
CMP conditioner's polishing pad. This conditioning surface 2, has
abrasive grains 3 distributed, then fixed with binding phase 4;
thus forming adhesive layer 5. The circumferential surface of
conditioner body 1, and the opposite side of the conditioning
surface 2, are attached to resin chassis 6; the chassis 6 has a
contour that fits the dimensions of the conditioner.
[0016] In this embodiment, the abrasive grains 3 are diamond
super-abrasive grains that have about the same average diameter,
which are arranged approximately in a regular grid on the
conditioning surface 2. The abrasive grains 3 protrude from the
binding phase 4 surface by pressure adjustment during
fabrication.
[0017] The binding phase 4 is made of low temperature co-fired
ceramics; this embodiment uses MgO--SiO.sub.2 ceramics and the
conditioner body 1 is also made of MgO--SiO.sub.2 or SiC
ceramics.
[0018] To fabricate this CMP conditioner: On one circular side of a
disc-shaped base of pre-sintered ceramics, the abrasive grains 3
are distributed and arranged, then they are sintered at
temperatures lower than 1000.degree. C. Preferably, this sintering
is preformed using spark plasma sintering; in which a raw object is
placed in a mold structured by carbon dies and punches; this is
placed under pressure and sintered using spark plasma generated by
applying direct pulse currents to that raw object.
[0019] FIG. 2 shows the abovementioned raw object as an example of
conditioner material, during fabrication of the CMP conditioner in
this embodiment. In this example, a pre-sintered ceramic base 11
made of MgO--SiO.sub.2 or SiC, one surface of this will become the
conditioning surface 2; on this surface, a layer of low temperature
co-fired sheet ceramics material 12 made of abovementioned
materials, in the form of a sheet or foil with the thickness of 1
mm or less is placed: On that, abrasive grains 3 such as diamond
super-abrasive grains, etc., are adhered using paste 13. On top of
that alumina powder, SiC powder, or a sheet made of the granulation
of these powders; these are placed as release agent 14.
[0020] To prepare such conditioner material, for example, an
abovementioned low temperature co-fired sheet ceramics material 12
is cut to fit the dimensions of the ceramics base 11; this sheet
has abovementioned liquid paste 13 sprayed on it; on the sprayed
surface, mesh having the grid size of the average grain size of
abrasive grains 3 is placed; then the abrasive grains 3 are
distributed on the mesh. The abrasive grains 3 that pass though the
mesh are adhered by paste 13; the surplus grains 3 are removed by
wiping, then the mesh is removed. Thus the fixed abrasive grains 3
form a uniform grid pattern that matches the mesh. Then the low
temperature co-fired sheet ceramics material 12 with the abrasive
grains 3 fixed on it, is placed on the surface of the ceramic base
11; a coat of the above-mentioned release agent 14 is placed on it,
thus forming the conditioner material shown in FIG. 2.
[0021] The obtained conditioner material is set in the
abovementioned mold, then placed in the spark plasma sintering
system that will perform the spark plasma sintering. As the spark
plasma sintering is performed under pressure, the abrasive grains 3
sink into the low temperature co-fired ceramics material 12, then
the low temperature co-fired ceramics material 12 with the abrasive
grains 3 fixed, becomes integrated with ceramic base 11; thus the
abovementioned CMP conditioner body 1 will have, on it's
conditioning surface 2; a firmly fixed single layer of abrasive
grains 3, this becomes the abrasive grain layer 5. The fabrication
of the CMP conditioner of the embodiment is completed when the
chassis 6, is attached to the CMP conditioner body 1.
[0022] In CMP conditioners with such structure, the abrasive grain
layer 5 has abrasive grains 3 fixed with binding phase 4; this
binding phase 4 is formed when the low temperature co-fired
ceramics material 12 is sintered, at the sintering temperature of
1000.degree. C. or lower. For example, in this embodiment, the
diameter of the conditioning surface 2 is 30 mm, the abrasive
grains 3 are diamond super-abrasive grains with the average grain
size of 280 Mm, the above-mentioned low temperature co-fired sheet
ceramics material 12 is made of MgO--SiO.sub.2 ceramics, at the
thickness is about 0.4 mm. To sinter this by spark plasma
sintering, the above-mentioned material is pressured at 20 KN for 1
minute at room temperature, then the temperature is increased to
650.degree. C. in 5 minutes, next, the temperature is increased to
750.degree. C. in 1 minute, the temperature is further increased to
800.degree. C. for 1 minute, maintained at 800.degree. C. for 1
minute, decreased to 300.degree. C. in 10 minutes, then removed
from the mold and cooled at room temperature, thus obtaining the
above-mentioned conditioner body 1.
[0023] If the abrasive grains 3 and low temperature co-fired
ceramics material 12 is the same as above and the conditioner
surface 2 diameter is 98 mm sintering by spark plasma sintering can
be used. To sinter this by spark plasma sintering, the material is
pressured at 20 KN for 1 minute at room temperature, then the
temperature is increased 150.degree. C. in 4 minutes, next, the
temperature is increased to 700.degree. C. in 5 minutes,
temperature increased to 800.degree. C. in 2 minutes, temperature
increased to 850.degree. C. in 2 minutes, the temperature is
maintained at 850.degree. C. for 1 minute, then the temperature is
decreased to 300.degree. C. in 100 minutes, then removed from the
mold and cooled at room temperature.
[0024] Dissolution of one or several metals such as Fe, Co, Ni, Cu,
and Zn occurs in CMP conditioners using metal plating phase as the
binding phase. In CMP conditioners in this embodiment, fabricated
and structured as previously mentioned, the conditioner body 1 is
made of ceramics including the abrasive grain layer 5 and the
binding phase 4. Thus, there is very little such dissolution, 1 ppm
or less, or no dissolution at all. If strong alkaline or strong
acid slurry is used in the CMP conditioner, the conditioner body 1
will not corrode or the abrasive grains 3 is not dissociated. The
conditioner body 1, made of ceramics, is mounted onto chassis 6,
made of resin, attachments to join it to the CMP apparatus, such as
screw holes can be made on chassis 6; there is no need to machine
the conditioner body 1.
[0025] In our abovementioned CMP conditioner, the abovementioned
binding phase 4 is made of low temperature co-fired ceramics
material 12 such as MgO--SiO.sub.2 ceramics; the sintering
temperature is 1000.degree. C. or lower. Thus, if the abrasive
grains 3 are diamond super-abrasive grains, they do not become
blackened or carbonized and there is no need to coat the surface of
the abrasive grains 3. The chipping that occurs in the abrasive
grains 3 and the poor cutting performance by coating, leading to
decrease the polishing rate of pad, are prevented. In our CMP
conditioner with the abovementioned structure, the wafer
contamination due to dissolved metals or the scratches on the
wafers from the chipping of abrasive grains can be prevented, while
the polishing pad is in reliable condition, thus making possible
efficient polishing of semiconductor wafers.
[0026] To fabricate such CMP conditioners, the above-mentioned
fabrication method uses, as conditioner material 12, low
temperature co-fired ceramics material mentioned in the embodiment;
this is sintered by spark plasma sintering. This spark plasma
sintering makes it possible to increase the temperature of the raw
object in a relatively short period of time; it is also possible to
sinter at lower temperatures, thus reliably preventing damage to
abrasive grains 3. Compared to sintering performed in a
conventional electric oven, the binding phase 4 sintered by spark
plasma sintering has lesser pores and a denser structure; the
Al.sub.2O.sub.3 particles as a filler have sufficiently melted,
hence almost none of Al.sub.2O.sub.3 remains as spherical shape,
thus making it possible to reliability retain abrasive grains
3.
[0027] An example of the above mentioned conditioner materials used
to fabricate the conditioning body 1 of such CMP conditioners. A
low temperature co-fired sheet ceramics material 12 is placed on
the surface of the above-mentioned pre-sintered ceramic base 11, on
that, abrasive grains 3, such as diamond super-abrasive grains are
arrayed regularly by a mesh, and adhered by paste 13. Another
example of preferable structure is shown in FIG. 3. A pre-sintered
ceramic base 11 has a low temperature co-fired sheet ceramics
material 12 cut to fit the dimensions of the surface of the ceramic
base 11; numerous holes 12a in a grid pattern are opened in the
sheet, the hole size being approximately the same or somewhat
smaller than the average diameter of the abrasive grains 3.
Abrasive grains 3, in this case diamond super-abrasive grains are
distributed on the holes 12a, the surplus abrasive grains 3 that
did not fit in the holes 12a are removed; then low temperature
co-fired ceramics material 12 with the abrasive grains 3 are placed
on the surface of base 11, on that, an alumina sheet is placed as
released agent 14.
[0028] The abovementioned materials are sintered, preferably by
spark plasma sintering, to construct a CMP conditioner. Since the
structure of this CMP conditioner is the same as the conditioner of
the embodiment, the efficiency is the same. Furthermore, the same
sintering conditions are applied to the embodiment and the
abovementioned materials.
[0029] As shown in these examples, conditioner body 1 with an
integrated abrasive grain layer 5 is formed by a pre-sintered
ceramic base 11 has low temperature co-fired ceramics material 12
placed on it, then it is sintered at low temperatures. FIG. 4 shows
other examples of conditioner material. A mold, preferably from a
spark plasma sintering system, has, as release agent, ceramics coat
agent placed in it, then the ceramic material 15 in powder form is
spread on the release agent 16. Placed on top of the ceramic
material 15 is, in one abovementioned example, a low temperature
co-fired sheet ceramics material 12 with the abrasive grains 3;
these are the same material as placed on the surface of ceramic
base 11. In another abovementioned example, the same low
temperature co-fired sheet ceramics material 12, has holes 12a
opened in it to attach the abrasive grains 3, then, an alumina
sheet is placed on top as release agent 14. Then low temperature
sintering is performed on both cases.
[0030] When low temperature co-fired ceramics material 12 is placed
on ceramic material 15 and sintered at low temperatures, it is
preferable that both ceramic material 15 and low temperature
co-fired ceramics material 12 used here are the same materials.
Thus the whole conditioner body 1, including the binding phase 4
and abrasive grain layer 5, can be efficiently sintered together at
low temperature. If low temperature co-fired ceramics material 12
and material 15 with the binding phase 4 are sintered together, the
CMP conditioner has an abrasive grain layer 5 with a higher ability
to retain the abrasive grains 3. This advantage is especially
evident when both low temperature co-fired ceramics material 12 and
material 15 are the same low temperature co-fired ceramics
material, such as MgO--SiO.sub.2 ceramics.
[0031] In these before-mentioned other examples, the conditioner
body 1 is integrally molded by low temperature co-fired ceramics
materials 15 placed in a mold, then sintered. In yet another
example, shown in FIG. 5, as the material of the raw object, the
mold has release agent 16 put in; on that, material 15 is spread,
then the diamond super-abrasive grains 3 are directly arrayed
regularly; on that an alumina sheet is placed as release agent 14,
and then, sintered at low temperatures. In this case, abrasive
grains 3 are fixed in binding phase 4; forming abrasive layer 5,
thus the whole of conditioner body 1 is formed by the integrated
sintering of low temperature co-fired ceramics. Thus the ability to
retain the abrasive grains 3 increases.
[0032] In conditioner material(s) shown in FIG. 4 and FIG. 5, the
powder form material 15 is spread in a mold, then sintered together
at low temperatures with binding phase 4. If the abrasive grains 3
and low temperature co-fired ceramics material 12 are the same as
the above-mentioned example; and if the material 15 in powder form
and the low temperature co-fired ceramics material 12 are of the
same composition sintering by spark plasma sintering can be used.
To sinter a conditioner body 1 having a conditioning surface 2 with
a diameter of 30 mm by using the spark sintering plasma, the
material is pressured to 20 KN at room temperature for 1 minute,
then the temperature is increased to 650.degree. C. in 5 minutes,
the temperature is increased to 750.degree. C. in 1 minute, the
temperature is increased to 800.degree. C. in 1 minute. These steps
are the same as the above-mentioned example. The next step differs
from the abovementioned case in that the whole conditioner body 1
including material 15 is sintered; thus it is maintained at
800.degree. C. for 5 minutes. Afterwards is the same as the
abovementioned example, the temperature is decreased to 300.degree.
C. in 10 minutes, taken out of the mold and cooled at room
temperature.
* * * * *