U.S. patent application number 14/848897 was filed with the patent office on 2016-08-11 for retainer ring, polishing apparatus, and manufacturing method of semiconductor device.
The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA. Invention is credited to Akifumi GAWASE, Kenji IWADE, Takahiko KAWASAKI, Yukiteru MATSUI.
Application Number | 20160229026 14/848897 |
Document ID | / |
Family ID | 56566459 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160229026 |
Kind Code |
A1 |
KAWASAKI; Takahiko ; et
al. |
August 11, 2016 |
RETAINER RING, POLISHING APPARATUS, AND MANUFACTURING METHOD OF
SEMICONDUCTOR DEVICE
Abstract
In accordance with an embodiment, a polishing apparatus includes
a polishing table and a polishing head. A retainer ring is attached
to a surface of the polishing head. The surface of the polishing
head faces the polishing table. The retainer ring includes a
ceramic material. The fracture toughness of the ceramic material is
4 MPam.sup.1/2 or more.
Inventors: |
KAWASAKI; Takahiko; (Nagoya,
JP) ; MATSUI; Yukiteru; (Nagoya, JP) ; IWADE;
Kenji; (Yokkaichi, JP) ; GAWASE; Akifumi;
(Kuwana, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA |
Tokyo |
|
JP |
|
|
Family ID: |
56566459 |
Appl. No.: |
14/848897 |
Filed: |
September 9, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24B 37/32 20130101 |
International
Class: |
B24B 37/32 20060101
B24B037/32 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2015 |
JP |
2015-020854 |
Claims
1. A retainer ring comprising: a ceramic material, the fracture
toughness of the ceramic material being 4 MPam.sup.1/2 or more.
2. The retainer ring of claim 1, wherein the Young's modulus of the
ceramic material is 400 GPa or less.
3. The retainer ring of claim 1, wherein the ceramic material
comprises at least one of substances selected from the group
consisting of zirconia (ZrO.sub.2), alumina (Al.sub.2O.sub.3),
silicon carbide (SiC), silicon nitride (SiN), yttria
(Y.sub.2O.sub.3), and cordierite
(2MgO2Al.sub.2O.sub.35SiO.sub.2).
4. A polishing apparatus comprising: a polishing table; and a
polishing head with a retainer ring attached to a surface of the
polishing head facing the polishing table, wherein the retainer
ring comprises a ceramic material, and the fracture toughness of
the ceramic material is 4 MPa.sup.,m.sup.1/.sup.2 or more.
5. The apparatus of claim 4, wherein the Young's modulus of the
ceramic material is 400 GPa or less.
6. The apparatus of claim 4, wherein the ceramic material comprises
at least one of substances selected from the group consisting of
zirconia (ZrO.sub.2), alumina (Al.sub.2O.sub.3), silicon carbide
(SiC), silicon nitride (SiN), yttria (Y.sub.2O.sub.3), and
cordierite (2MgO2Al.sub.2O.sub.35SiO.sub.2).
7. A manufacturing method of a semiconductor device, the method
comprising rotating a polishing table to which a polishing pad is
attached, and rotating a substrate held by a retainer ring attached
to a polishing head while pressing the substrate to the polishing
pad, thereby polishing the substrate, wherein the retainer ring
comprises a ceramic material, and the fracture toughness of the
ceramic material is 4 MPam.sup.1/2 or more.
8. The apparatus of claim 4, wherein the Young's modulus of the
ceramic material is 400 GPa or less.
9. The apparatus of claim 4, wherein the ceramic material comprises
at least one of substances selected from the group consisting of
zirconia (ZrO.sub.2), alumina (Al.sub.2O.sub.3), silicon carbide
(SiC), silicon nitride (SiN), yttria (Y.sub.2O.sub.3), and
cordierite (2MgO2Al.sub.2O.sub.35SiO.sub.2).
Description
CROSS REFERENCE TO RELATED
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2015-020854, filed on Feb. 5, 2015, the entire contents of which
are incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate generally to a retainer
ring, a polishing apparatus, and a manufacturing method of a
semiconductor device.
BACKGROUND
[0003] In a manufacturing process of a semiconductor device,
chemical mechanical polishing (hereinafter referred to as "CMP") is
used to flatten, for example, an insulating film, a metallic film,
or a polycrystalline silicon film buried in a trench which is
provided in a surface of a polishing object by patterning. A CMP
apparatus generally holds the rear surface (the surface opposite to
a polishing surface) of the polishing object by a polishing head to
press the surface (polishing surface) of the polishing object onto
a polishing pad to which slurry is supplied, and relatively rotate
the polishing head and the polishing pad, thereby flattening the
insulating film, the metallic film, or polycrystalline silicon
buried in the trench in the surface of the polishing object.
[0004] The polishing head which holds the polishing object is
provided with a mechanism which applies pressure to the rear
surface of the polishing object, and a retainer ring which prevents
the polishing object from protruding to outside of the polishing
head during the relative rotation of the polishing head and the
polishing pad.
[0005] The retainer ring as well as the polishing object is pressed
onto the polishing pad. Therefore, if the fracture toughness is
low, wear rapidly progresses due to the repetition of polishing,
and the frequency of replacement increases, so that the costs of
consumable materials increase, and time loss caused by replacement
work is a problem.
[0006] Impact from the polishing object is also applied to the
retainer ring. Therefore, partial wear occurs such that wear more
significantly progresses on the side of the polishing object than
on the side opposite to the polishing object. In this case, the
outer peripheral part of the polishing object is excessively
polished.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In the accompanying drawings:
[0008] FIG. 1 is an example of a perspective view showing a
schematic configuration of a polishing apparatus (CMP apparatus)
according to one embodiment;
[0009] FIG. 2 is an example of a sectional view of a polishing pad
provided in the polishing apparatus shown in FIG. 1;
[0010] FIG. 3 is an example of a perspective view showing a
schematic configuration of a retainer ring according to one
embodiment;
[0011] FIG. 4 is an example of a flowchart illustrating the outline
of a manufacturing method of the retainer ring shown in FIG. 3;
[0012] FIG. 5 is a table showing an example of an experimental
result showing wear amounts of various ceramic materials;
[0013] FIG. 6 is an example of a diagram illustrating force which
is applied to the retainer ring during polishing;
[0014] FIG. 7 is an example of a diagram illustrating a rebound
from the polishing pad in an initial state of use;
[0015] FIG. 8 is an example of a diagram illustrating a rebound
from the polishing pad after the partial wear of the retainer ring
has progressed;
[0016] FIG. 9 is an example of a graph showing the relation between
the polishing rate and the distance from the center of a polishing
object by the comparison between the initial state and the state in
which the partial wear has already progressed in the retainer
ring;
[0017] FIG. 10 is an example of a graph showing the relation
between the fracture toughness of the retainer ring and the
incidence of chipping;
[0018] FIG. 11 is an example of a diagram illustrating how the side
surface of the polishing object is chipped by stress resulting from
the collision with the retainer ring;
[0019] FIG. 12 is an example of a graph showing the relation
between the Young's modulus of the retainer ring and the incidence
of chipping in the polishing object; and
[0020] FIG. 13 is an example of a table showing the fracture
toughness and Young's modulus for each ceramic material.
DETAILED DESCRIPTION
[0021] In accordance with an embodiment, a polishing apparatus
includes a polishing table and a polishing head. A retainer ring is
attached to a surface of the polishing head. The surface of the
polishing head faces the polishing table. The retainer ring
includes a ceramic material, The fracture toughness of the ceramic
material is 4 MPam.sup.1/2 or more.
[0022] Embodiments will now be explained with reference to the
accompanying drawings, Like components are provided with like
reference signs throughout the drawings and repeated descriptions
thereof are appropriately omitted. It is to be noted that the
accompanying drawings illustrate the invention and assist in the
understanding of the illustration and that the shapes, dimensions,
and ratios and so on in each of the drawings may be different in
some parts from those in an actual apparatus.
[0023] First, a polishing apparatus according to one embodiment is
described with reference to FIG. 1 to FIG. 3.
[0024] FIG. 1 is an example of a perspective view showing a
schematic configuration of a polishing apparatus (CMP apparatus)
according to the present embodiment.
[0025] A polishing apparatus 1 shown in FIG. 1 includes a polishing
table 2, a polishing head 3, a diamond dresser 4, a polishing
solution supply opening 5, a pure water supply opening 6, and a
cleaning solution supply opening 7.
[0026] A polishing pad 8 is attached to the upper surface (the
surface facing the polishing head 3) of the polishing table 2. The
polishing table 2 is configured to be rotatable and drivable by a
driver (not shown) including a motor.
[0027] The polishing head 3 is configured to be rotatable and
drivable by a driver (not shown) including a motor. This polishing
head 3 is configured to be able to press the upper surface (the
surface facing the polishing head 3) of the polishing pad 8 with
predetermined pressure while rotating, for example, a semiconductor
wafer W (see FIG. 2) which is a polishing object. The detailed
configuration of the polishing head 3 will be described later in
detail.
[0028] The diamond dresser 4 conditions the surface of the
polishing pad 8. The diamond dresser 4 is rotated and driven by a
driver (not shown) including a motor, and is configured to be
pressed by the polishing pad 8.
[0029] The polishing solution supply opening 5, the pure water
supply opening 6, and the cleaning solution supply opening 7 are
configured to be able to respectively supply a polishing solution
(e.g. slurry), pure water, and a cleaning solution onto the
polishing pad 8 at predetermined flow volumes.
[0030] The specific structure of the polishing head 3 is described
with reference to FIG. 2, FIG. 2 is an example of a sectional view
along the cutting-plane line A-A in FIG. 1.
[0031] The polishing head 3 includes circular-plate-shaped head
body 10, a membrane 12, and a retainer ring 11 corresponding to one
embodiment. The head body 10 is configured to be supported by an
arm (not shown). The membrane 12 is held by the retainer ring 11 so
as to contact the lower surface (the surface facing the polishing
pad 8) of the head body 10. The retainer ring 11 is attached to the
lower surface of the head body 10, and holds the semiconductor
wafer W in such a manner that the surface of the semiconductor
wafer W opposite to the polishing surface contacts the lower
surface of the membrane 12.
[0032] The semiconductor wafer W thus held by the retainer ring 11
is pressed to the polishing pad 8 by the head body 10 and the
membrane 12.
[0033] A schematic configuration of the retainer ring 11 is shown
in a perspective view in FIG. 3, The retainer ring 11 according to
the present embodiment is manufactured by the use of a ceramic
material as a whole, and has a fracture toughness of 4 MPam.sup.1/2
or more and a Young's modulus of 400 GPa or less.
[0034] The outline of a manufacturing method of this retainer ring
11 is described with reference to FIG. 4, In the present
embodiment, a ceramic is formed by the use of a cold isostatic
press (CIP) method.
[0035] Specifically, a ceramic material (powder) is put into a
rubber-state mold formed to adapt to the shape of a target retainer
ring (step 1), and the mold is then inserted into a high-pressure
container (step 2) and isotropically pressurized via a pressure
medium (liquid) (step 3). As the ceramic material, for example,
zirconia (ZrO.sub.2), alumina (Al.sub.2O.sub.3), silicon carbide
(SiC), silicon nitride (SiN), yttria (Y.sub.2O.sub.3), and
cordierite (2MgO2Al.sub.2O.sub.35SiO.sub.2) can be used (see FIG.
13).
[0036] A primary process to form a groove (not shown) of the
retainer ring is then performed (step 4), and a sinter process is
performed to eliminate holes in the ceramic material (step 5).
Finally, a finish process is performed as a secondary process, and
the retainer ring 11 is thereby obtained (step 6).
[0037] FIG. 5 shows the wear amounts that are obtained by
conducting experiments under the same experimental environment for
each of the above-mentioned ceramic materials. As obvious from FIG.
5, it is confirmed that the ceramic materials can reduce the wear
amounts 50 times or more as compared to polyphenylene sulfide (PPS)
which is a generally used retainer ring material.
[0038] The degree of fracture toughness is a problem in the
manufacture of the retainer ring. This is because if the retainer
ring is manufactured by the use of a material having a fracture
toughness of less than 4 MPam.sup.1/2, the retainer ring may break
due to insufficient pressure during the CIP formation or may break
from a slight crack or the like occurring during mechanical
processing for forming the grooves in the primary process.
[0039] In contrast, when a material having a fracture toughness of
4 MPam.sup.1/2 or more is used to manufacture the retainer ring by
the CIP formation method, it was confirmed that the retainer ring
can be satisfactorily manufactured without breakage or the
like.
[0040] In CMP, the polishing head 3 and the polishing pad 8 are
relatively rotated to flatten the surface of the semiconductor
wafer W. Therefore, force from the polishing pad 8 is applied to
the retainer ring 11 as indicated by the arrow AR1 in FIG. 6, and
force which causes the semiconductor wafer W to protrude to the
outside of the polishing head 3 as indicated by the arrow AR2 in
FIG. 6 is also repeatedly applied to the retainer ring 11 for every
polishing. As a result of the repetition of such impacts in a
lateral direction (a direction level with the surface of the
polishing pad 8 facing a processing surface of the semiconductor
wafer W), the inner surface of the retainer ring 11 may be chipped
as indicated by the sign CP1 in FIG. 6.
[0041] In an initial state of use of the retainer ring 11, rebounds
from the polishing pad 8 equally occur inside and outside the
retainer ring 11 as shown in FIG. 7. However, if a chip CP1 occurs
in the inner surface of the retainer ring 11, wear progresses from
the crack, and partial wear progresses accordingly. The progress of
the partial wear affects the state of a rebound from the polishing
pad. For example, as shown in FIG. 8, rebounds from the polishing
pad 8 concentrate inside the retainer ring 11, and a polishing rate
is enhanced at a wafer edge, thus resulting in a wafer edge
excessive polishing state.
[0042] An example of this wafer edge excessive polishing state is
shown in a graph of FIG. 9. It is obvious from FIG. 9 that in the
region of a wafer edge, due to the repetition of the polishing
process, the polishing rate after the partial wear has progressed
is significantly higher than the polishing rate in the initial
state.
[0043] FIG. 10 is an example of a graph showing the relation
between the fracture toughness of the retainer ring and the
incidence of chipping. From FIG. 10 it is confirmed that the
incidence of chipping is 0 when the fracture toughness is 4
MPam.sup.1/2 or more.
[0044] The retainer ring 11 according to the present embodiment has
a fracture toughness of 4 MPam.sup.1/2 or more, thus chipping in
the inner surface of the retainer ring 11 is inhibited.
Consequently, the occurrence of the partial wear can be
inhibited.
[0045] Meanwhile, the impact by the (lateral) force during
polishing which causes the semiconductor wafer W to protrude to the
outside of the polishing head 3 is not only applied to the retainer
ring 11 but also applied to the side of the semiconductor wafer W,
and stress is repeatedly generated by collision between the
semiconductor wafer W and the retainer ring 11. Therefore, if a
retainer ring 11 manufactured by the use of a hard material is
used, a chip CP2 may occur in the side surface of the semiconductor
wafer W by receiving repetitive stress in the direction of the
arrow AR3, as shown in FIG. 11.
[0046] One index that indicates the hardness (the degree of the
elastic modulus) of a material is the Young's modulus (the
physicality value [GPa] that indicates the difficulty of
deformation). Stronger impact is applied to the semiconductor wafer
W in the case of materials that are less deformable, so that the
degree of the impact applied to the semiconductor wafer W can be
judged by the degree of the Young's modulus of the retainer ring
11.
[0047] FIG. 12 is an example of a graph showing the relation
between the Young's modulus of the retainer ring 11 and the
incidence of chipping in the semiconductor wafer W. From FIG. 12 it
is confirmed that desired buffering effect required to inhibit the
chipping in the semiconductor wafer W can be obtained if the
Young's modulus of the retainer ring 11 is 400 GPa or less.
[0048] The fracture toughness and Young's modulus of respective
selectable ceramic materials are shown in a table of FIG. 13. As
obvious from FIG. 13, it is possible to manufacture a retainer ring
11 having a fracture toughness of 4 MPam.sup.1/2 or more and a
Young's modulus is 400 GPa or less by the use of SiN. However, the
material is not limited to SIN, and it is also possible to
manufacture a retainer ring having desired physicality by selecting
purity and the kind of binder or by combining the ceramic materials
when, for example, other ceramic materials shown in FIG. 13 are
used.
[0049] The retainer ring according to at least one embodiment
described above includes the ceramic material, so that the progress
of wear can be inhibited.
[0050] In addition, the retainer ring according to at least one
embodiment described above has a fracture toughness of 4
MPam.sup.1/2 or more, so that the progress of partial wear can be
inhibited.
[0051] Furthermore, the retainer ring according to at least one
embodiment described above has a Young's modulus is 400 GPa or
less, so that it is possible to prevent the polishing object from
being damaged.
[0052] The polishing apparatus 1 according to at least one
embodiment described above includes the retainer ring including the
ceramic material, so that the frequency of the replacement of the
retainer ring decreases, the throughput of the polishing process
improves, and the polishing object can be thus polished at low
cost.
[0053] In addition, the polishing apparatus 1 according to at least
one embodiment described above includes the retainer ring having a
fracture toughness of 4 MPam.sup.1/2 or more, so that the polishing
object can be polished without uneven polishing and without the
chipping in the retainer ring.
[0054] Furthermore, the polishing apparatus 1 according to at least
one embodiment described above includes the retainer ring having a
Young's modulus of 400 GPa or less, so that it is possible to
inhibit the polishing object from being damaged.
[0055] Next, a manufacturing method of a semiconductor device
according to one embodiment is described. The manufacturing method
according to the present embodiment includes a polishing process
using the polishing apparatus 1 shown in FIG. 1.
[0056] First, a semiconductor wafer W in which an insulating film,
a metallic film, a polycrystalline silicon film, and others are
formed by, for example, patterning is prepared.
[0057] The semiconductor wafer W is then brought into contact with
the polishing pad 8 in such a manner that the polishing surface of
the semiconductor wafer W faces the polishing pad 8 while the
semiconductor wafer W is held by the polishing head 3.
[0058] The polishing table is then rotated, for example, in the
direction of the arrow AR10 in FIG. 1 while a polishing solution
such as slurry, pure water, and a cleaning solution are
respectively supplied onto the polishing pad 8 at predetermined
flow volumes via the polishing solution supply opening 5, the pure
water supply opening 6, and the cleaning solution supply opening 7.
Moreover, while the semiconductor wafer W is held by the retainer
ring 11, the semiconductor wafer W is pressed to the polishing pad
8 by the head body 10 and the membrane 12 and at the same time
rotated, for example, in the direction of the arrow AR20 in FIG. 1,
Thus, polishing targets such as the silicon film, the metallic
film, and the insulating film formed on the semiconductor wafer W
are polished by the relative rotation of the polishing pad 8 and
the semiconductor wafer W. A semiconductor device is manufactured
on the semiconductor wafer W by the repetition of the film
formation process and the polishing process.
[0059] During polishing, the surface part of the semiconductor
wafer W is returned to the initial state before polishing by the
diamond dresser 4 in order to prevent the surface part of the
polishing pad 8 from being worn or being clogged with abrasive
grains included in an abrasive due to the polishing of the
semiconductor wafer W.
[0060] The polishing pad 8 and the polishing head 3 are preferably
rotated and driven together, from the perspective of eliminating
the unevenness of the polishing amount of the semiconductor wafer
W. When these portions are rotated and driven, the rotation
direction of the polishing pad 8 and the rotation direction of the
polishing head 3 are preferably the same as shown in FIG. 1.
Although both the polishing pad 8 and the polishing head 3
respectively rotate in the directions of the arrows AR10 and AR20
in the case shown in FIG. 1, it should be understood that these
portions do not exclusively rotate in this direction, and may
rotate in directions opposite to the above directions.
[0061] According to the manufacturing method of the semiconductor
device in at least one embodiment described above, the substrate is
polished by the use of the polishing apparatus 1 provided with the
retainer ring 11 including the ceramic material, so that the costs
of consumable materials are reduced, and the manufacturing costs of
the semiconductor device can be reduced.
[0062] In addition, according to the manufacturing method of the
semiconductor device in at least one embodiment described above,
the substrate is polished by the use of the polishing apparatus 1
provided with the retainer ring 11 having a fracture toughness of 4
MPam.sup.1/2 or more, so that it is possible to prevent the
excessive polishing of a substrate edge region resulting from the
partial wear of the retainer ring. Consequently, the substrate can
be accurately polished, so that it is possible to improve the yield
of the semiconductor device.
[0063] Furthermore, according to the manufacturing method of the
semiconductor device in at least one embodiment described above,
the substrate is polished by the use of the polishing apparatus 1
provided with the retainer ring 11 having a, Young's modulus of 400
GPa or less, so that it is possible to prevent the substrate from
being chipped, and improve the yield of the semiconductor
device.
[0064] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to emit the scope of the inventions. Indeed, the novel
methods and systems described herein may be embodied in a variety
of other forms; furthermore, various omissions, substitutions and
changes in the form of the methods and systems 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 or modifications as would fall within the scope and
spirit of the inventions.
* * * * *