U.S. patent application number 12/794472 was filed with the patent office on 2011-04-07 for polishing device and polishing method.
Invention is credited to Yukiteru Matsui, Kenro Nakamura, Takeshi Nishioka.
Application Number | 20110081832 12/794472 |
Document ID | / |
Family ID | 43823536 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110081832 |
Kind Code |
A1 |
Nakamura; Kenro ; et
al. |
April 7, 2011 |
POLISHING DEVICE AND POLISHING METHOD
Abstract
In one embodiment, a polishing device includes: a rotatable
turntable, a holding unit, a separation wall, a slurry supply tube,
and a cooling medium supply tube. On an upper surface of the
rotatable turntable, a polishing pad is attached. The holding unit
rotatably holds an object to be polished and disposes a polished
surface of the object to be polished in a manner to face the
polishing pad. The separation wall abuts on the upper surface of
the polishing pad and sections the polishing pad into a polished
region in which the holding unit is provided and an unpolished
region in which the holding unit is not provided. The slurry supply
tube supplies a slurry to the upper surface of the polishing pad in
a polished region side. The cooling medium supply tube supplies a
cooling medium to the upper surface of the polishing pad in the
unpolished region.
Inventors: |
Nakamura; Kenro;
(Kamakura-shi, JP) ; Matsui; Yukiteru;
(Yokohama-shi, JP) ; Nishioka; Takeshi;
(Yokohama-shi, JP) |
Family ID: |
43823536 |
Appl. No.: |
12/794472 |
Filed: |
June 4, 2010 |
Current U.S.
Class: |
451/28 ;
451/177 |
Current CPC
Class: |
B24B 57/02 20130101;
B24B 55/02 20130101; B24B 37/10 20130101 |
Class at
Publication: |
451/28 ;
451/177 |
International
Class: |
B24B 1/00 20060101
B24B001/00; B24B 7/04 20060101 B24B007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 5, 2009 |
JP |
P2009-231447 |
Claims
1. A polishing device, comprising: a rotatable turntable on an
upper surface of which a polishing pad is attached; a holding unit
rotatably holding an object to be polished and disposing a polished
surface of the object to be polished in a manner to face the
polishing pad; a separation wall abutting on the upper surface of
the polishing pad and sectioning the polishing pad into a polished
region in which said holding unit is provided and an unpolished
region in which said holding unit is not provided; a slurry supply
tube supplying a slurry to the upper surface of the polishing pad
in a polished region; and a cooling medium supply tube supplying a
cooling medium to the upper surface of the polishing pad in the
unpolished region.
2. The polishing device as set forth in claim 1, wherein the
polished region and the unpolished region includes a donut-shaped
polish contact surface made as a result that the polishing pad
being rotated contacts the holding unit.
3. The polishing device as set forth in claim 1, wherein said
separation wall has a U shape in plain view and a bottom portion of
the U shape is disposed in a neighborhood of a rotation center of
the polishing pad.
4. The polishing device as set forth in claim 1, wherein a
constitution material of at least a part of a surface of said
separation wall contains any one of polyether ether ketone (PEEK),
polyphenylene sulfide (PPS), and fluorine.
5. The polishing device as set forth in claim 1, wherein said
cooling medium supply tube is movable in a radial direction of the
polishing pad.
6. The polishing device as set forth in claim 1, wherein said
cooling medium supply tube supplies a temperature-controlled
cooling medium.
7. The polishing device as set forth in claim 1, wherein a
plurality of said cooling medium supply tubes is provided along a
radial direction of the polishing pad and said cooling medium
supply tubes are each independently controlled to supply the
cooling medium.
8. The polishing device as set forth in claim 1, wherein said
cooling medium supply tube has a showerhead with numerous pores
facing the upper surface of the polishing pad.
9. The polishing device as set forth in claim 1, wherein the
cooling medium is pure water.
10. The polishing device as set forth in claim 1, wherein the
cooling medium is gas.
11. A polishing method, comprising: preparing a rotatable turntable
on an upper surface of which a polishing pad is attached; preparing
a holding unit rotatably holding an object to be polished and
disposing a polished surface of the object to be polished in a
manner to face the polishing pad; making a separation wall abut on
the polishing pad and sectioning the polishing pad into a polished
region in which the holding unit is provided and an unpolished
region in which the holding unit is not provided; rotating the
turntable thereby to rotate the polishing pad; supplying a cooling
medium cooling a surface of the polishing pad in the unpolished
region; supplying a slurry in the polished region; and rotating the
object to be polished and pressing the object to be polished to the
polished region to which the slurry has been supplied.
12. The polishing method as set forth in claim 11, wherein the
separation wall has a U shape in plain view and a bottom portion of
the U shape is disposed in a neighborhood of a rotation center of
the polishing pad.
13. The polishing method as set forth in claim 11, wherein a
constitution material of at least a part of a surface of the
separation wall contains any one of polyether ether ketone (PEEK),
polyphenylene sulfide (PPS), and fluorine.
14. The polishing method as set forth in claim 11, wherein the
cooling medium supply tube is movable in a radial direction of the
polishing pad.
15. The polishing method as set forth in claim 11, wherein the
cooling medium supply tube supplies a temperature-controlled
cooling medium.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2009-231447, filed on Oct. 5, 2009; the entire contents of which
are incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate generally to a polishing
device and a polishing method used for a CMP (Chemical Mechanical
Polishing) method.
BACKGROUND
[0003] Recently, in a manufacturing field of a semiconductor
device, as semiconductor devices become highly densified and
miniaturized, various microfabrication technologies are used. Among
those technologies, a chemical mechanical polishing (CMP)
technology is essential for planarization of an interlayer
insulation film, formation of a plug, formation of a buried metal
wiring, buried metal isolation or the like.
[0004] In a polishing device for CMP, a turntable on whose upper
surface a polishing pad is attached is rotated in a horizontal
plane, and a slurry is supplied by a slurry supply tube from above
the polishing pad. The slurry wets an entire surface of the
polishing pad and a slurry layer is formed on the polishing pad.
While a top ring holding a semiconductor wafer is rotated in the
horizontal plane in the same direction as rotation of the
turntable, the top ring presses this polishing pad. A surface to be
polished of the semiconductor wafer is polished by being rubbed
against the polishing pad via the slurry.
[0005] Due to heat generation by such rubbing (friction), a
temperature of the surface of the polishing pad rises. The
temperature rise is made larger by the following conditions (1) to
(4). (1) Pressing force of the semiconductor wafer to the polishing
pad is large. (2) A rotation speed of the top ring or the turntable
is large. (3) A flow amount of the slurry is small. (4) An area of
the semiconductor wafer is large.
[0006] Thus, the surface temperature of the polishing pad may
sometimes exceed several ten degrees, 50.degree. C. for example. As
a result, the surface of the polishing pad is softened, and there
is a possibility that a planarization characteristic of the
semiconductor wafer in a CMP process is deteriorated. The
semiconductor wafer has a tendency to have a larger diameter as the
generation advances. Further, in view of cost reduction, there is a
tendency that a flow amount of a slurry per semiconductor wafer
unit area is reduced. Therefore, there is a possibility that the
temperature rise of the polishing pad becomes larger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1A is a front view schematically showing a polishing
device according to a first embodiment and showing a part thereof
by a cross section (hatching portion).
[0008] FIG. 1B is a top view schematically showing the polishing
device according to the first embodiment and showing a part thereof
by a cross section (hatching portion).
[0009] FIG. 1C is a view schematically showing the polishing device
according to the first embodiment and is a cross-sectional view of
a separation wall along a line X-Y in FIG. 1B.
[0010] FIG. 1D is a view schematically showing the polishing device
according to a variation of the first embodiment and is a
cross-sectional view of a separation wall along a line X-Y in FIG.
1B.
[0011] FIG. 2 is a graph showing a temperature distribution of a
polishing pad of the polishing device according to the first
embodiment.
[0012] FIG. 3 is a top view schematically showing a polishing
device according to a second embodiment and showing a part thereof
by a cross section (hatching portion).
[0013] FIG. 4A is a front view schematically showing a polishing
device according to a third embodiment and showing a part thereof
by a cross section (hatching portion).
[0014] FIG. 4B is a top view schematically showing the polishing
device according to the third embodiment and showing a part thereof
by a cross section (hatching portion).
[0015] FIG. 5 is a graph showing a temperature distribution of a
polishing pad of the polishing device according to the third
embodiment.
DETAILED DESCRIPTION
[0016] In one embodiment, a polishing device includes a rotatable
turntable, a holding unit, a separation wall, a slurry supply tube,
and a cooling medium supply tube. On an upper surface of the
rotatable turntable, a polishing pad is attached. The holding unit
rotatably holds an object to be polished and disposes a polished
surface of the object to be polished in a manner to face the
polishing pad. The separation wall abuts on the upper surface of
the polishing pad and sections the polishing pad into a polished
region in which the holding unit is provided and an unpolished
region in which the holding unit is not provided. The slurry supply
tube supplies a slurry to the upper surface of the polishing pad in
a polished region. The cooling medium supply tube supplies a
cooling medium to the upper surface of the polishing pad in the
unpolished region.
[0017] Hereinafter, embodiments will be described with reference to
the drawings. In the following drawings, the same reference numeral
is given to the same component.
First Embodiment
[0018] A polishing device and a polishing method according to a
first embodiment will be described with reference to FIG. 1A and
FIG. 1B.
[0019] As shown in FIG. 1A and FIG. 1B, a polishing device 1 has,
schematically, a turntable 11, a separation wall 21, a top ring 25,
a slurry supply tube 31, and a cooling medium supply tube 35. The
turntable 11 is housed in a casing 15 in which a funnel 16 is
provided along an outer periphery of the turntable 11. The
separation wall 21 sections a polishing pad 12 on the turntable 11.
The top ring 25 is a holding unit to hold a semiconductor wafer 27
being an object to be polished.
[0020] The turntable 11 has a radius in which the top ring 25
holding the semiconductor wafer 27 can be placed. The polishing pad
12 is attached on an upper surface of the turntable 11. The
polishing pad 12 is formed of polyurethane foam for example, and
more specifically, of IC1000/SUBA400 of Rodel Nitta Co., Ltd. and
so on. The polishing pad 12 of the turntable 11 is rotated in a
horizontal plane. A rotation direction is clockwise as shown in
FIG. 1B (shown by an arrow) for example.
[0021] Above the turn table 11 is disposed the top ring 25
suction-holding the semiconductor wafer 27 with a surface to be
polished, a semiconductor device surface for example, facing to the
polishing pad therebelow. The top ring 25 is rotated in the same
direction (shown by an arrow) as that of the turntable 11 in
horizontal plane. During the polishing, a surface to be polished of
the semiconductor wafer 27 is pressed at a certain pressure so as
to contact a surface of the polishing pad 12.
[0022] The top ring 25 has a retainer ring 29 disposed around the
semiconductor wafer 27. An object of the retainer ring 29 is to
prevent the semiconductor wafer 27 from deviating from the top ring
25 at a time of polishing and to prevent an edge portion of the
semiconductor wafer 27 from being over-polished. However, it is
possible not to use the retainer ring 29.
[0023] At the time of polishing, in a region (polish contact
surface 37) excluding a center portion and a peripheral portion on
the polishing pad 12, the polishing pad 12 and the top ring 25
holding the semiconductor wafer 27 contact each other. The polish
contact surface 37 is an assemblage of trajectories on the
polishing pad 12 made by the top ring 25 contacting the polishing
pad 12. The polish contact surface 37 has a donut shape indicated
by a broken line. It should be noted that a polish contact surface
of the polishing pad 12 and the semiconductor wafer 27 is a region
within the polish contact surface 37.
[0024] The separation wall 21 has a U shape (shape projecting
toward a polished region 43 described later) in plain view for
example. A bottom surface portion of the U shape of the separation
wall 21 is disposed in the center portion of the polishing pad 12,
that is, a position corresponding to a hole inside the polish
contact surface 37 of a donut shape. The separation wall 21 is bent
from the U-shaped bottom surface portion toward upper end portions,
and the surface of the polishing pad 12 is sectioned in the U shape
from a center to an outer periphery. The bent separation wall 21
contacts the outer periphery of the polishing pad 12 at two places
in plain view. The separation wall 21 contacts the surface of the
polishing pad 12 from right overhead. In other words, a side
surface of the separation wall 21 is almost vertical to the
polishing pad 12.
[0025] The separation wall 21 is bent in a crank shape in a
direction of departing upward from the surface of the polishing pad
12 and further in a horizontal direction, outside the outer
periphery of the polishing pad 12. The two places of the upper end
portions of the U shape of the separation wall 21 are fixed to the
casing 15. Fixing of the separation wall 21 to the casing 15 is
done by a press jig 23 to which a spring is attached for example so
that the separation wall 21 is able to be pressed constantly. It is
preferable that a press load at which the separation wall 21
presses the polishing pad 12 is set to be equal to or lower than
9.8 kPa (100 gf/cm.sup.2). It is because friction heat between the
separation wall 21 and the polishing pad 12 becomes large when the
press load is made large.
[0026] Two places of the separation wall 21 contacting the outer
periphery of the polishing pad 12 are apart from each other by
about one fourth of the outer periphery for example along the outer
periphery of the polishing pad 12. A portion surrounded by the
separation wall 21 and about one fourth of the outer periphery of
the polishing pad 12 is a region in which the top ring 25 is not
provided, that is, an unpolished region 41. A portion (portion
surrounded by the separation wall 21 and about three fourth of the
outer periphery of the polishing pad 12) except the unpolished
region 41 is a polished region 43. The top ring 25 is provided in
the polished region 43.
[0027] The separation wall 21 can be divided into portions 21A and
21B at the center portion of the polishing pad 12. In a rotation
direction upstream of the polishing pad 12 in the unpolished region
41, the portion 21A has a curve projecting toward the upstream.
Further, in a rotation direction downstream of the polishing pad
12, the portion 21B has a curve projecting toward the downstream.
It should be noted that the upstream means a side which the rotated
polishing pad 12 first reaches within the unpolished region 41.
[0028] The top ring 25 is generally disposed in a center portion of
the polished region 43 (that is, in a position, in the polished
region 43, opposite to the unpolished region 41 in relation to the
center of the polishing pad 12) along the rotation direction of the
polishing pad 12. It should be noted that the top ring 25 and the
unpolished region 41 are not required to be placed opposite to each
other in relation to the center of the polishing pad 12. The top
ring 25 can be disposed on one side of the part 21B of the
separation wall 21. This makes a cooling efficiency higher because
the cooled polishing pad 12 reaches directly under the top ring 25
within a short time.
[0029] As shown in FIG. 10, a cross section of the separation wall
21 is an almost rectangle with corners contacting the polishing pad
12 rounded. A height of the separation wall 21 is a height with
which a later-described cooling medium does not flow over above the
separation wall 21, about 2 cm for example. A width of the
separation wall 21 is a width durable to a dynamic friction force
from the rotated polishing pad 12. A material of the separation
wall 21 is required to have a high chemical resistance and a high
abrasion resistance. As the material, there can be used a material
equivalent to that for the retainer ring 29 of the top ring 25, for
example, polyether ether ketone (PEEK), polyphenylene sulfide
(PPS), polycarbonate (PC), fluorine based resin, ceramic, and the
like. It should be noted that in the separation wall 21 only a
portion contacting the slurry can be made of such a material.
[0030] On the surface of the polishing pad 12, hollows, for
example, recesses or dimples, generally exists. The liquid cooling
medium collected in the hollow can reach into the polishing area 43
to dilute the slurry. To prevent it, it is effective to add a brush
36 on the inner corner (Y side) of the separation wall 21.
[0031] Above the polishing pad 12 in the polished region 43, the
slurry supply tube 31 for supplying a slurry and a pure water
supply tube 33 for supplying pure water for water polishing to the
polished region 43 are each provided. The slurry supply tube 31 and
the pure water supply tube 33 are able to drop the slurry and the
pure water respectively to a place in the upstream side of the
rotation direction of the polishing pad 12 in relation to the top
ring 25 and in a position close to the rotation center of the
polishing pad 12. It should be noted that the place on which the
slurry and the pure water are dropped can be changed by moving
liquid dropping ports of the slurry supply tube 31 and the pure
water supply tube 33. Components of the slurry are different by an
object of CMP. The slurry is dispersion liquid of polishing grains
to which a chemical is added in general, in case that the object is
made of tungsten, alumina dispersion liquid to which iron nitrate
is added.
[0032] Above the polishing pad 12 in the unpolished region 41, the
cooling medium supply tube 35 with a showerhead for supplying a
cooling medium is provided. The cooling medium supply tube 35,
provided in a proper position of the polishing pad 12, a position
close to the rotation center for example, is capable of dispersing
a cooling medium of pure water. Here, supply of the cooling medium
is performed with the showerhead with numerous pores instead of a
tube with a single opening. This is for the purpose of increasing
chances of contact between the cooling medium and the polishing pad
12 thereby to improve a cooling efficiency. It should be noted that
when a semiconductor wafer 27 having a comparatively small
diameter, a cooling medium supply tube 35 with a single opening can
be used.
[0033] A place to which the cooling medium is supplied can be
changed by moving the showerhead (supply port) of the cooling
medium supply tube 35. Further, by changing an orientation of the
showerhead (supply port) of the cooling medium supply tube 35, a
direction in which the cooling medium is supplied can be changed. A
flow amount, a temperature or the like of the cooling medium can be
optimized. When the temperature of the cooling medium is to be made
lower than a room temperature, a cold heat source (not shown) for
example is wound around the cooling medium supply tube 35 thereby
to cool the cooling medium. It should be noted that a moving system
of the cooling medium supply tube 35 and the shower head, a flow
amount control system, a temperature control system and the like
are not shown. Further, the cooling medium can be water to which a
surfactant is added, other than pure water. In such a case, an
effect of washing the polishing pad 12 soiled by adhesion of the
polishing grain can be expected secondarily. Further, the cooling
medium is not limited to liquid, but gas such as nitrogen and
atmosphere can be used.
[0034] Next, a polishing method using the polishing device 1 will
be described.
[0035] In the polishing device 1, as described above, the polishing
pad 12 is attached on the turntable 11. The U-shaped separation
wall 21 sectioning the polishing pad 12 into the unpolished region
41 and the polished region 43 is fixed to the casing 15 by the
press jig 23. The separation wall 21 is made to abut on the
polishing pad 12. As a result, the unpolished region 41 is secured
continuously from the center of the polishing pad 12 in an outer
periphery direction.
[0036] The turntable 11 is rotated at a predetermined rotation
speed, at 60 rpm for example. Then, above the rotated polishing pad
12, in the unpolished region 41 sectioned by the separation wall
21, the cooling medium is supplied via the cooling medium supply
tube 35. The cooling medium spreads from the center of the
polishing pad 12 in the unpolished region 41 in the entire outer
periphery direction. Part of the cooling medium is made to flow to
an outer periphery side by a centrifugal force due to rotation of
the polishing pad and falls into the funnel 16. Other part of the
cooling medium hits against the separation wall 21 (the part 21B)
in the rotation direction downstream side of the polishing pad 12,
moves along a wall surface of the curved separation wall 21 (the
part 21B), and falls into the funnel 16. The flow amount of the
cooling medium is about 200 cm.sup.3 per minute (200 ml/min) for
example.
[0037] The slurry is dropped in the polished region 43 sectioned by
the separation wall 21 on the rotated polishing pad 12, via the
slurry supply tube 31.
[0038] Thereafter, the top ring 25 holding the semiconductor wafer
27 is conveyed to right above the polished region 43, and is let
down while being rotated at a predetermined rotation speed, at 63
rpm for example. Further, the top ring 25 is pressed at a
predetermined pressure, at 19.6 kPa (200 gf/cm.sup.2) for example,
and the surface to be polished, the semiconductor device surface
for example, of the semiconductor wafer 27 is made contact with the
surface (polish contact surface 37) of the polishing pad 12.
Polishing proceeds by rubbing the semiconductor device surface of
the semiconductor wafer 27 against the polishing pad 12 on which
the slurry is distributed.
[0039] Part of the slurry of the polished region 43 is made to flow
to the outer periphery side by the centrifugal force by the
rotation of the polishing pad 12 and falls into the funnel 16.
Other part of the slurry hits against the separation wall (the part
21A) in the downstream of the polished region 43 (upstream of the
unpolished region 41) and moves along the wall surface of the
curved separation wall 21 (the part 21A), discharged into the
funnel 16.
[0040] When polishing of a predetermined thickness is finished,
supply of the slurry is stopped. Subsequently, pure water for water
polishing is dropped from the pure water supply tube 33 and water
polishing is performed, whereby the slurry adhered to the
semiconductor wafer 27 is rinsed away. When water polishing is
finished, supply of the cooling medium is stopped. However, supply
of the cooling medium can be stopped or reduced when polishing is
finished. It is because friction heat at the time of water
polishing is small since a load at a time of water polishing is
generally smaller than a load at a time of polishing.
[0041] The semiconductor wafer 27 on which water polishing after
polishing is finished is conveyed to a post-polishing module (not
shown) and a post-polishing process is performed. In the same time,
usual dressing is performed by a dresser (not shown) on the
polishing pad 12. This dressing is performed by rubbing the dresser
against the polishing pad 12. If dressing is performed after the
top ring 25 is retracted, there is no problem if an operation
region of the top ring 25 and an operation region of the dresser
overlap with each other. After dressing is finished, the top ring
25 holding a semiconductor wafer 27 to be polished next is conveyed
to right above the polished region 43, and the semiconductor wafer
27 is similarly polished.
[0042] As stated above, the polishing method in the polishing
device 1 in which the separation wall 21 is provided is not
basically different from that of a polishing device without a
separation wall 21. However, slurry gradually adheres to the
separation wall 21 in the polished region 43. Thus, if such an
adherent drops and reaches beneath the semiconductor wafer 27 under
being polished, a scratch may be sometimes generated in a surface
to be polished of the semiconductor wafer 27. Therefore, it is
preferable to add a removing process of such an adherent. For
example, every time a predetermined number of semiconductor wafers
27 is processed, a procedure is performed in which the separation
wall 21 is made in a state of being held up from the polishing pad
12 and washed with a hand shower or the like. Further, it is
possible to make a system capable of performing such washing
automatically.
[0043] Next, an effect obtained by CMP by using the polishing
device 1 will be described.
[0044] Note a temperature distribution in a measure line 45 (two
dot chain line) in a neighborhood of the top ring 25 on the
polishing pad 12, shown in FIG. 1B. The measure line 45 is a line
located in a radial direction of the polishing pad 12 and included
in the polish contact surface 37. Besides, the measure line 45 is
positioned in a downstream side of the top ring 25 in relation to
the rotation direction of the polishing pad 12. A temperature in
the measure line 45 is measured by a radiation thermometer. Since
this temperature is a temperature of the polishing pad 12 soon
after polishing, this temperature can be substituted for a
temperature of the polishing pad 12 directly under the
semiconductor wafer 27.
[0045] FIG. 2 is a graph indicating a position of the measure line
45 by a horizontal axis and a temperature by a vertical axis. In a
polishing device without cooling, that is, in a conventional
polishing device, the temperatures exceed 50.degree. C. and are
approximately 60.degree. C. in a center portion. On the other hand,
in a polishing device with cooling, that is, in the polishing
device 1 of the present embodiment, the temperatures including a
temperature in the center portion are equal to or lower than
40.degree. C. Further, in the polishing device 1, a difference
between a maximum temperature and a minimum temperature is
decreased.
[0046] Therefore, in the polishing device without cooling, that is,
in the conventional polishing device, the polishing pad 12 is
softened due to temperature rise. Therefore, a planarization
characteristic of polishing is deteriorated and a global level
difference (difference in height between the highest place and the
lowest place) due to polishing of the semiconductor wafer 27
reaches as much as 100 nm. On the other hand, in the polishing
device with cooling, that is, in the polishing device 1 of the
present embodiment, softening of the polishing pad 12 is suppressed
since temperature rise is suppressed. Therefore, a planarization
characteristic of polishing is maintained and a global level
difference (difference in height between the highest place and the
lowest place) due to polishing of the semiconductor wafer 27 is
suppressed to 20 nm.
Second Embodiment
[0047] A polishing device and a polishing method according to a
second embodiment will be described with reference to FIG. 3. What
is different from the polishing device 1 of the first embodiment is
that a separation wall has a dogleg shape in plain view. It should
be noted that the same reference numeral is given to the same
component as that in the first embodiment and explanation thereof
will be omitted.
[0048] As shown in FIG. 3, in a polishing device 2, a separation
wall 51 has a dogleg shape, while the separation wall 21 in the
polishing device 1 of the first embodiment has the U shape. In the
dogleg-shaped separation wall 51, two places contacting an outer
periphery of the polishing pad 12 are apart from each other by
about one fourth of the outer periphery along the outer periphery
of the polishing pad 12. Here, a distance between press jigs 23 is
larger compared with that in the first embodiment.
[0049] Consider to divide the dogleg-shaped separation wall 51 in
plain view into two portions 51A, 51B (first and second curved
portions) at a bent portion. The portions 51A, 51B each correspond
to each of portions (portions 21A, 21B) of the U-shaped separation
wall 21 of the polishing device 1 of the first embodiment, the
separation wall 21 cut in a manner that the two portions become
plane symmetry. In other words, in a rotation direction upstream of
the polishing pad 12 in a polished region 41, the portion 51A has a
curb projecting toward the upstream. The portion 51B also has, in a
rotation direction downstream of the polishing pad 12, a curb
projecting toward the upstream. The bent portion (border between
the portions 51A, 51B) in the dogleg shape in plain view of the
separation wall 51 is positioned in a center portion of the
polishing pad 12. Other constitutions are the same as those of the
polishing device 1 of the first embodiment. The polishing method is
also the same as that in the polishing device 1 of the first
embodiment.
[0050] With regard to the separation wall 51, in the unpolished
region 41, a curvature in the downstream side is reverse to a
curvature in the first embodiment. As a result, in the polishing
device 2 it is easy to dispose the top ring 25 close to the
separation wall 51. Since the cooled polishing pad 12 reaches
directly under the top ring 25 in a short time, a cooling
efficiency is improved. It should be noted that the shape of the
separation wall 51 can be changed from the dogleg shape to a V
shape. In other words, the portions 51A, 51B are each to have a
linear shape instead of a curved shape. In such a case, a position
of the top ring 25 is required to be apart from the dogleg-shaped
separation wall in some degree, but a V-shaped separation wall 51
is easy to be formed.
[0051] The polishing device 2 similarly has the effect the
polishing device 1 of the first embodiment has.
Third Embodiment
[0052] A polishing device and a polishing method according to a
third embodiment will be described with reference to FIG. 4A and
FIG. 4B. What is different from the polishing device 1 of the first
embodiment is that a plurality of cooling medium supply tubes is
provided. It should be noted that the same reference numeral is
given to the same component as that in the first embodiment and
explanation thereof will be omitted.
[0053] As shown in FIG. 4A and FIG. 4B, a polishing device 3 is
provided with a plurality of cooling medium supply tubes 55. Other
constitutions are the same as those in the polishing device 1 of
the first embodiment. The cooling medium supply tubes 55 are
disposed in a manner that their supply ports cover a donut-shaped
polish contact surface 37 in a radial direction almost linearly
from a center of a polishing pad 12 in an outer periphery direction
along a radius in an unpolished region 41.
[0054] Each of the cooling medium supply tubes 55 can be
independently controlled in terms of a temperature of a cooling
medium, a flow amount, and a position of the supply port. It should
be noted that it is possible that one cooling medium supply tube 55
is constituted to have a plurality of supply ports and that three
cooling medium supply tubes 55 are provided for example thereby to
supply the cooling medium from six supply ports.
[0055] Further, the supply port of the cooling medium supply tube
55 can be a showerhead. Further, with regard to the cooling medium
supply tubes 55, an array of the supply ports are not limited to a
linear array in a radial direction. The supply ports can be
disposed curvedly along a separation wall 21 for example so that a
temperature distribution of a polishing pad 12 can be better
controlled. Further, the separation wall 21 can be replaced by the
separation wall 51 of the second embodiment.
[0056] The polishing method by the polishing device 3 is the same
as that of the polishing device 1 of the first embodiment except
that the cooling medium is supplied from plural cooling medium
supply tubes 55.
[0057] In the polishing device 3 it is possible to make the
temperature distribution of the polishing pad 12 have a desired
shape by independently controlling temperatures, flow amounts and
the like of the plural cooling medium supply tubes 55. In other
words, it is possible to make the temperature distribution on the
measure line 45 shown in the first embodiment be flat as shown in
FIG. 5. This is attained by lowering the temperature of the cooling
medium at the center portion of the polish contact surface 37 among
the plural cooling medium supply tubes 55 or increasing the flow
amount of the cooling medium at the center portion.
[0058] By performing a CMP processing by using the polishing device
3 in which such a temperature distribution of the polishing pad 12
is realized, it is possible, in a semiconductor wafer 27, to make a
characteristic of a semiconductor device formed therein more
uniform.
[0059] The polishing device 3, in addition, similarly has the
effect the polishing device 1 of the first embodiment has.
[0060] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
instead to limit the scope of the inventions. Indeed, the novel
methods and devices described herein may be embodied in a variety
of other forms; furthermore, various emissions, substitutions and
changes in the form of the methods and devices described herein may
be made without departing from the spirit of the inventions. The
accompanying claims and their equivalents are intended to cover
such forms of modifications as would fall within the scope and
spirit of the inventions.
[0061] For example, in the embodiment there is described an example
of the separation wall in which two places contacting the outer
periphery of the polishing pad are apart from each other by about
one fourth of the outer periphery of the polishing pad. In
contrast, it is also possible to set two places to be apart from
each other by less than or more than one fourth of the polishing
pad outer periphery. It suffices if desired cooling of a polishing
pad is performed in an unpolished region sectioned by a separation
wall.
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