U.S. patent application number 11/088786 was filed with the patent office on 2005-10-06 for polishing apparatus and method of polishing a subject.
Invention is credited to Nakagawa, Yasutada, Nakahata, Masaomi, Terada, Takahiro.
Application Number | 20050221724 11/088786 |
Document ID | / |
Family ID | 34858460 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050221724 |
Kind Code |
A1 |
Terada, Takahiro ; et
al. |
October 6, 2005 |
Polishing apparatus and method of polishing a subject
Abstract
A polishing apparatus. The polishing apparatus has an abrasive
cloth and a table to rotate the abrasive cloth. A holder holds a
subject to be polished against the abrasive cloth. A discharger
discharges a polishing solution from the abrasive cloth after the
polishing solution passes between the abrasive cloth and the
subject.
Inventors: |
Terada, Takahiro; (Tokyo,
JP) ; Nakahata, Masaomi; (Kanagawa-ken, JP) ;
Nakagawa, Yasutada; (Kanagawa-ken, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER
LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
34858460 |
Appl. No.: |
11/088786 |
Filed: |
March 25, 2005 |
Current U.S.
Class: |
451/41 |
Current CPC
Class: |
B24B 37/04 20130101;
B24B 57/02 20130101 |
Class at
Publication: |
451/041 |
International
Class: |
B24B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 25, 2004 |
JP |
2004-089296 |
Claims
What is claimed is:
1. A polishing apparatus, comprising: an abrasive cloth; a table to
rotate the abrasive cloth; a holder configured to hold a subject to
be polished against the abrasive cloth; and a discharger to
discharge a polishing solution from the abrasive cloth after the
polishing solution passes between the abrasive cloth and the
subject
2. A polishing apparatus according to claim 1, further comprising a
supplying mechanism to supply the polishing solution onto the
abrasive cloth.
3. A polishing apparatus according to claim 1, wherein the
discharger comprises a dam.
4. A polishing apparatus according to claim 1, wherein the holder
comprises a top ring to rotate the subject, the discharger
comprises a flat wall, and an inclination of the flat wall with
reference to a plane which passes through a rotational axis of both
the rotary table and the top ring is -10 through -90 degrees with
the clockwise rotation viewed from the top face of the rotary table
assumed to be positive.
5. A polishing apparatus according to claim 1, wherein the
discharger comprises a blower.
6. A polishing apparatus according to claim 1, wherein the
discharger comprises an absorber to absorb the polishing
solution.
7. A polishing apparatus according to claim 1, wherein the
discharger comprises a suction unit to suck in the polishing
solution.
8. A polishing apparatus according to claim 1, wherein the abrasive
cloth is bonded on the top surface of the rotary table.
9. A polishing apparatus according to claim 2, wherein the
discharger comprises a plate to dam the polishing solution, and
wherein the plate is up the polishing solution stream from the
supplying mechanism.
10. A polishing apparatus according to claim 3, wherein the dam
exerts force on the polishing solution in a radially outward
direction of the rotary table.
11. A polishing apparatus according to claim 3, wherein the dam
includes a flat wall to dam the polishing solution.
12. A polishing apparatus according to claim 3, wherein the dam
includes a curved wall to dam the polishing solution.
13. A polishing apparatus according to claim 9, wherein the holder
is a top ring to rotate the subject and wherein a plane which
passes through a rotational axes of both the rotary table and the
top ring separates the plate from the supplying mechanism.
14. A method of polishing a subject, comprising: rotating an
abrasive cloth; providing a polishing solution between the subject
and the abrasive cloth; and discharging the polishing solution from
the abrasive cloth after the polishing solution passes between the
subject and the abrasive cloth.
15. A method of polishing a subject according to claim 14, wherein
rotating an abrasive cloth includes rotating an abrasive cloth on a
rotary table.
16. A method of polishing a subject according to claim 15, wherein
discharging the polishing solution includes exerting force on the
polishing solution in a radially outward direction of the rotary
table.
17. A method of polishing a subject according to claim 16, wherein
exerting force on the polishing solution includes exerting force on
the polishing solution using a plate.
18. A method of polishing a subject according to claim 16, wherein
exerting force on the polishing solution includes blowing air
toward the polishing solution in a radially outward direction of
the rotary table.
19. A method of polishing a subject according to claim 14, wherein
discharging the polishing solution includes absorbing the polishing
solution.
20. A method of polishing a subject according to claim 14, wherein
discharging the polishing solution includes sucking in the
polishing solution.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2004-089296
filed on Mar. 25, 2004, the entire contents of which are
incorporated herein by reference.
BACKGROUND
[0002] 1. TECHNICAL FIELD
[0003] This invention relates to a polishing apparatus and a method
of polishing a subject, in particular, to a polishing apparatus
using chemical mechanical polishing (CMP) method and a method of
polishing a subject using the CMP method.
[0004] 2. DESCRIPTION OF THE RELATED ART
[0005] FIGS. 10 and 11 show methods to supply a polishing solution
to an abrasive cloth bonded on a rotary table. A subject to be
polished is arranged on the abrasive cloth.
[0006] FIG. 10 is a schematic diagram of a polishing apparatus
shown in FIG. 7 of Japanese Patent Disclosure (kokai) No.
07-156063. The polishing apparatus is provided with a pump 73 to
supply a polishing solution 72 contained in a container 71 onto an
abrasive cloth 76 bonded on a top surface of a rotary table 75. A
wafer W on abrasive cloth 76 is polished by the supplied polishing
solution 72. A funnel 77 receives polishing solution 72 driven off
the surface of rotary table 75 by a centrifugal force. The received
polishing solution 72 is drained as waste liquid 78 without
circulating.
[0007] FIG. 11 shows another polishing apparatus shown in FIG. 1 of
the same Japanese Patent Disclosure. The polishing apparatus is
provided with a plate 2 directing toward a rotational center 3 of a
rotary table 1, in order to let a polishing solution flow toward
rotational center 3, which polishing solution would have been
driven off the surface of the rotary table 1 without plate 2. In
other words, plate 2 dams up the polishing solution and exerts
force in a radially inward direction of rotary table 1 on the
dammed polishing solution.
[0008] The method of supplying polishing solution 72 shown in FIG.
10 is expensive since almost all of the polishing solution 72
supplied onto the surface of abrasive cloth 76 is driven off
without being used for the polishing. Then, the actual amount of
polishing solution 72 supplied between wafer W and abrasive cloth
76 is quite limited. In other words, an application efficiency of
polishing solution 72 is so low that a cost of a polishing process
becomes high. The polishing apparatus shown in FIG. 11 is also not
efficient since the apparatus does not have a distinguished
polishing rate.
SUMMARY
[0009] There is a polishing apparatus consistent with the present
invention. The apparatus comprises an abrasive cloth, a table to
rotate the abrasive cloth, a holder configured to hold a subject to
be polished against the abrasive cloth, and a discharger to
discharge a polishing solution from the abrasive cloth after the
polishing solution passes between the abrasive cloth and the
subject.
[0010] In this invention, an abrasive cloth includes a polishing
pad ,and a table includes a rotary table or a platen, and a holder
includes top ring or polishing head or wafer carrier.
BRIEF DESCRIPTION OF THE DRAWING
[0011] FIG. 1 is a schematic diagram of a polishing apparatus
100.
[0012] FIG. 2 is a schematic plan view of a rotary table 1 of
polishing apparatus 100.
[0013] FIG. 3 is a drawing to define an angle of a plate 6.
[0014] FIG. 4 shows a relation between a kind of a slurry and a pH
value.
[0015] FIG. 5 shows a relation between a pH value and a polishing
rate.
[0016] FIG. 6 shows a relation between a flow rate and a polishing
rate.
[0017] FIG. 7 is a schematic diagram of a polishing apparatus
200.
[0018] FIG. 8 is a schematic diagram of a polishing apparatus
300.
[0019] FIG. 9 is a schematic diagram of a polishing apparatus
400.
[0020] FIG. 10 is a schematic diagram of a conventional polishing
apparatus.
[0021] FIG. 11 is a plan view of a rotary table 1 of another
conventional polishing apparatus.
DETAILED DESCRIPTION
[0022] A first embodiment consistent with the present invention is
explained with reference to FIGS. 1 to 6.
[0023] The inventors of the present invention have identified that
a pH value of a used slurry (a used polishing solution) is lower
than that of an unused slurry, and that a polishing rate
deteriorates with a lowering of a pH value of a slurry. The
inventors have concluded that reducing slurry consumption only by
circulating a used slurry is of limited value.
[0024] In this embodiment, a used slurry is not tried to be
accumulated or maintained on a surface of an abrasive cloth but
willingly discharged from the surface of the abrasive cloth.
[0025] FIG. 1 shows a schematic diagram of a polishing apparatus
100.
[0026] Polishing apparatus 100 is provided with a rotary table 9
(table) rotated by a motor (not shown), an abrasive cloth 1 bonded
on the top surface of rotary table 9 and a top ring 2 (holder) to
hold and rotate a subject to be polished such as a semiconductor
wafer. Top ring 2 is movably arranged. Polishing apparatus 100 is
also provided with a polishing solution supplying mechanism 3 to
supply a polishing solution onto abrasive cloth 1, and a plate 6
(discharger) to dam up a used polishing solution and discharge it
off abrasive cloth 1. A first arm 20 supports supplying mechanism 3
arranged above abrasive cloth 1. A second arm 22 whose position and
angle are changeable secures plate 6 above abrasive cloth 1 on
rotary table 9. A third arm 24 supports top ring 2 which rotates on
its axis.
[0027] Plate 6 may made of polycarbonate or fluorocarbon resin
which are alcaliproof. However, other materials can be substituted.
When worn, plate 6 can be replaced.
[0028] As to plate 6, a flat plate or a curbed plate may be used.
Further, a circular plate, a spiral plate or a plurality of flat
plates may be used. Moreover, an absorber to absorb a used
polishing solution off abrasive cloth 1 or a blower to blow
high-pressured air in a radially outward direction of the rotary
table to blow a used polishing solution may be used instead of
plate 6. Moreover, a suction unit to suck in a used polishing
solution on abrasive cloth 1 may be used. Other ways to discharge a
used polishing solution from the surface of abrasive cloth 1 may be
substituted for plate 6.
[0029] An operation of polishing apparatus 100 will be explained
next. A polishing solution is supplied onto a dripping position
(supplying position) of abrasive cloth 1 while rotary table 9 with
abrasive cloth 1 rotates. Plate 6 is arranged above abrasive cloth
1 in advance. Top ring 2 holding the subject to be polished
rotates. Thus, the subject is polished. FIG. 2 shows a current
direction of the polishing solution (slurry) on abrasive cloth
1.
[0030] A side wall of plate 6 facing top ring 2 is defined as an
A-side (FIG. 2), and the other side wall facing the dripping
position is defined as a B-side in this embodiment. Used slurry,
after passing between the subject and abrasive cloth 1 collides
with the A-side of plate 6. Then, plate 6 exerts force on the
collided slurry in a radially outward direction of abrasive cloth 1
(rotary table 9). The used slurry moves along with the A-side.
Consequently, the used slurry is discharged from abrasive cloth 1.
Meanwhile, unused slurry which does not flow between the subject
and abrasive cloth 1 collides with the B-side. The B-side exerts
force on the collided unused slurry in a radially inward direction
of abrasive cloth 1 (rotary table 9) so that the collided unused
slurry moves toward the subject.
[0031] Next, a position of plate 6 will be explained in detail with
reference to FIG. 3. As shown in FIGS. 2 and 3, plate 6 is arranged
on an upstream side of the supplying position of the polishing
solution, and arranged on a downstream side of top ring 2 so that
plate 6 can effectively discharge the used polishing solution.
[0032] As shown in FIG. 3, an inclination of plate 6, which has a
flat wall, is defined as an angle with reference to a plane which
passes through the rotational axes of both the rotary table 9 and
the center of the top ring 2, assuming the clockwise rotation
viewed from the top face of rotary table 9 is positive.
[0033] In this embodiment, plate 6 is aligned with the angle
.theta. ranging from -10 through -90 degrees.
[0034] The surface of abrasive cloth 1 has two areas divided by the
line passing through the center of both the top ring 2 and the
rotary table 9. When the dripping position is involved in one area,
the plate 6 is arranged so as to be substantially involved in the
other area in a plan view. In other words, a plane which passes
through the rotational axes of both rotary table 9 and top ring 2
separates a region where almost all of plate 6 is involved from the
other region where the dripping position is involved.
[0035] FIG. 5 shows a relation between a kind of a slurry and a pH
value. As shown in FIG. 5, the pH value of the unused slurry is the
highest; a pH value of the used slurry is the lowest; and the
slurry in this embodiment is median.
[0036] FIG. 4 shows pH values of an unused slurry, a repeatedly
used slurry and a slurry on abrasive cloth 1 in this embodiment. As
shown in FIG. 4, a polishing rate improves as a pH value becomes
high. Therefore, a pH value of a slurry on abrasive cloth 1 is
maintained to keep a high polishing value by discharging the used
slurry from abrasive cloth 1. Consequently, the polishing rate of
the slurry in this embodiment is superior to that of the used
slurry.
[0037] FIG. 6 shows a relation between a flow rate of a slurry and
a polishing rate. In the figure, a 100% polishing rate is equal to
a polishing rate accomplished by the conventional method using a
100% flow rate.
[0038] Using the method shown in this embodiment, the flow rate can
be reduced by 70% without deteriorating the polishing rate.
[0039] A second embodiment is shown with reference to FIG. 7. An
absorber to absorb used polishing solution is used instead of plate
6. As to the absorber, a material having a permeability and a
porosity, such as a sponge, may be used. As shown in FIG. 7, a
compression roller 12 squeezes the polishing solution absorbed by a
sponge roller 11 to discharge the used polishing solution from the
surface of abrasive cloth 1. The squeezed out polishing solution is
drained with a trough 13. While squeezing, both the sponge roller
11 and the compression roller 12 rotate.
[0040] A third embodiment is shown with reference to FIG. 8. As
shown in FIG. 8, a suction nozzle (suction unit) instead of plate 6
may be used to remove used polishing solution.
[0041] A fourth embodiment is described next with reference to FIG.
9. High-pressured air instead of plate 6 may be used. An air nozzle
16 (blower) blows used slurry off abrasive cloth 1. Other means to
discharge a used slurry from abrasive cloth 1 may be used.
[0042] As well as discharging a used slurry, an unused slurry can
be recirculated and reused. In the first embodiment, plate 6 both
discharges a used slurry and circulates an unused slurry.
[0043] In these embodiments, a polishing solution includes a fluid
or a liquid containing an abrasive.
[0044] Numerous modifications of the present invention are possible
in light of the above teachings. It is therefore to be understood
that, within the scope of the appended claims, the present
invention can be practiced in a manner other than as specifically
described herein.
* * * * *