U.S. patent application number 16/806216 was filed with the patent office on 2021-02-11 for polishing apparatus and retainer ring.
This patent application is currently assigned to KIOXIA CORPORATION. The applicant listed for this patent is KIOXIA CORPORATION. Invention is credited to Takahiko KAWASAKI.
Application Number | 20210039224 16/806216 |
Document ID | / |
Family ID | 1000004720280 |
Filed Date | 2021-02-11 |
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United States Patent
Application |
20210039224 |
Kind Code |
A1 |
KAWASAKI; Takahiko |
February 11, 2021 |
POLISHING APPARATUS AND RETAINER RING
Abstract
According to one embodiment, a polishing apparatus includes a
polishing head having a retainer surrounding a substrate to be
polished, and a polishing pad facing the polishing head. The
retainer includes a first material and a second material. The first
material contains at least one of aromatic polyamide, polyphenylene
sulfide, polyetherimide, polyamideimide, polyetheretherketone, or
polybenzimidazole. The second material contains a fluororesin.
Inventors: |
KAWASAKI; Takahiko;
(Yokohama Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KIOXIA CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
KIOXIA CORPORATION
Tokyo
JP
|
Family ID: |
1000004720280 |
Appl. No.: |
16/806216 |
Filed: |
March 2, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24B 37/32 20130101;
B24B 37/24 20130101; B24B 37/0053 20130101 |
International
Class: |
B24B 37/32 20060101
B24B037/32; B24B 37/24 20060101 B24B037/24 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 8, 2019 |
JP |
2019-146541 |
Claims
1. A polishing apparatus comprising: a polishing head having a
retainer surrounding a substrate to be polished; and a polishing
pad facing the polishing head, wherein the retainer includes a
first material and a second material, wherein the first material
contains at least one of aromatic polyamide, polyphenylene sulfide,
polyetherimide, polyamideimide, polyetheretherketone (PEEK), or
polybenzimidazole, and wherein the second material contains a
fluororesin.
2. The polishing apparatus according to claim 1, wherein a weight
percentage of the second material with respect to the first
material is 1% to 10%.
3. The polishing apparatus according to claim 1, wherein the
fluororesin of the second material includes at least one of
polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), a
perfluoroethylene propene copolymer (FEP), an ethylene
tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride
(PVDF), polychlorotrifluoroethylene (PCTFE), ethylene
chlorotrifluoroethylene copolymer (ECTFE),
tetrafluoroethylene-perfluorodioxole copolymer (TFE/PDD), or
polyvinyl fluoride (PVF).
4. The polishing apparatus according to claim 3, wherein the first
material contains PEEK and the fluororesin of the second material
includes PTFE, and wherein the weight of PTFE with respect to the
weight of PEEK is 1% to 20%.
5. The polishing apparatus according to claim 1, wherein the
retainer is a retainer ring.
6. A retainer ring for use a polishing head for holding a substrate
to be polished, the retainer ring comprising: a first material and
a second material, wherein the first material contains at least one
of aromatic polyamide, polyphenylene sulfide, polyetherimide,
polyamideimide, polyetheretherketone (PEEK), or polybenzimidazole,
and wherein the second material contains a fluororesin.
7. The retainer ring according to claim 6, wherein a weight
percentage of the second material with respect to the first
material is 1% to 10%.
8. The retainer ring according to claim 6, wherein the fluororesin
includes at least one of polytetrafluoroethylene (PTFE),
perfluoroalkoxyalkane (PFA), a perfluoroethylene propene copolymer
(FEP), an ethylene tetrafluoroethylene copolymer (ETFE),
polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene
(PCTFE), ethylene chlorotrifluoroethylene copolymer (ECTFE),
tetrafluoroethylene-perfluorodioxole copolymer (TFE/PDD), or
polyvinyl fluoride (PVF).
9. The retainer ring according to claim 8, wherein the first
material contains PEEK and the fluororesin of the second material
includes PTFE, and wherein the weight of PTFE with respect to the
weight of PEEK is 1% to 20%.
10. A polishing head comprising the retainer ring of claim 6.
11. A polishing head comprising the retainer ring of claim 7.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of and priority to
Japanese Patent Application No. 2019-0146541, filed Aug. 8, 2019,
the entire contents of which are incorporated herein by
reference.
FIELD
[0002] Embodiments described herein relate generally to a polishing
apparatus and a retainer ring.
BACKGROUND
[0003] In a polishing apparatus used for chemical mechanical
polishing (CMP), a substrate (wafer) is generally pressed against a
polishing pad while being held by a polishing head. Subsequently,
when the polishing head and the polishing pad are rotated, a film
formed on a substrate surface is planarized.
[0004] The polishing head is generally provided with a retainer
ring that surrounds the substrate in the circumferential direction.
This retainer ring can prevent the substrate from jumping out of
the polishing head during polishing.
[0005] The retainer ring is pressed against the polishing pad in
the same manner as the substrate. For this reason, the retainer
ring also wears with the polishing of the wafer substrate. Since
the retainer ring is generally made of resin, wear progresses
quickly. As a result, the replacement frequency of the retainer
ring is increased.
DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a schematic diagram illustrating a schematic
configuration of a polishing apparatus according to an
embodiment.
[0007] FIG. 2 is a sectional view of a polishing head.
[0008] FIG. 3 is a diagram of a retainer ring as seen from a bottom
side.
[0009] FIG. 4 is a graph illustrating a relationship between a
material of the retainer ring and an abrasion loss.
[0010] FIG. 5 is a graph illustrating a polishing rate and
uniformity of a substrate for each material of the retainer
ring.
DETAILED DESCRIPTION
[0011] Embodiments provide a polishing apparatus which can reduce
abrasion of a retainer ring.
[0012] In general, according to one embodiment, there is provided a
polishing apparatus including a polishing head having a retainer
ring surrounding a substrate to be polished, and a polishing pad
facing the polishing head. The retainer ring may include a first
material and a second material. The first material may contain at
least one of aromatic polyamide, polyphenylene sulfide,
polyetherimide, polyamideimide, polyetheretherketone, and
polybenzimidazole. The second material may contain a fluororesin.
The weight percentage of the second material with respect to the
first material may be 1% to 10%.
[0013] Hereinafter, embodiments of the present disclosure will be
described with reference to the drawings. The present embodiment is
not intended to limit the present disclosure.
[0014] FIG. 1 is a schematic diagram illustrating a schematic
configuration of a polishing apparatus according to an embodiment.
A polishing apparatus 1 as illustrated in FIG. 1 includes a
polishing head 10, a polishing pad 20, and a nozzle 30. This
polishing apparatus 1 may be used in a process of chemical
mechanical polishing a substrate 100 in a wafer state.
[0015] FIG. 2 is a sectional view of the polishing head 10. As
illustrated in FIG. 2, the polishing head 10 includes a support 11,
a chucking plate 12, an elastic member 13, and a retainer ring 14.
In some embodiments, a retainer ring 14 may be replaced by a
retainer having a shape other than a ring.
[0016] The support 11 may be made of, for example, a resin, and a
pipe 111 is formed therein. The pipe 111 is branched, and a part of
a branch path extends to the chucking plate 12. The chucking plate
12 may be a ceramic disk, for example, and is provided in a lower
portion of the support 11. The elastic member 13 may be rubber, for
example, and is provided in the lower portion of the chucking plate
12. The elastic member 13 is divided into a plurality of regions by
a plate-like member 131 provided corresponding to the branch path
of the pipe 111.
[0017] In the polishing head 10, the pressure due to air 200
flowing into the pipe 111 may be applied to the substrate 100
through the elastic member 13, so that the substrate 100 is pressed
against the polishing pad 20. In the present embodiment, since the
pipe 111 is branched and the elastic member 13 is partitioned by
the plate-like member 131, for example, a force applied to a
central portion and an end portion of the substrate 100 can be
adjusted.
[0018] As illustrated in FIG. 2, the retainer ring 14 is provided
at the lower portion of the support 11 so as to surround the
substrate 100, the chucking plate 12, and the elastic member 13.
The retainer ring 14 may be pressed against the polishing pad 20 by
the air 200 introduced into the pipe 111.
[0019] FIG. 3 is a diagram of the retainer ring 14 as seen from a
bottom side. As illustrated in FIG. 3, grooves 141 are formed
radially on a bottom surface of the retainer ring 14, in other
words, on a contact surface with the polishing pad 20. When the
retainer ring 14 is pressed against the polishing pad 20 by the
groove 141, a gap is formed between them. Through this gap, a
slurry 300 (see FIG. 1) can flow into and out of the retainer ring
14.
[0020] As illustrated in FIG. 1, the polishing pad 20 is positioned
at a position facing the polishing head 10. In addition, a planar
area of the polishing pad 20 is larger than a planar area of the
substrate 100. The slurry 300 containing abrasive grains is
supplied to the surface of the polishing pad 20.
[0021] The nozzle 30 discharges the slurry 300 from above the
polishing pad 20. The slurry 300 may be, for example, ceria
slurry.
[0022] Hereinafter, a process of chemically polishing a film formed
on the substrate 100 using the above-described polishing apparatus
1 will be described. First, the nozzle 30 discharges the slurry 300
toward the surface of the polishing pad 20, and the polishing head
10 may press the film formed on the substrate 100 against the
polishing pad 20.
[0023] Subsequently, the polishing head 10 and the polishing pad 20
may be simultaneously rotated in the same direction. As a result, a
film embedded in the groove patterned on the surface of the
substrate 100, such as an insulating film, a metal film, or a
crystalline silicon film, may be planarized.
[0024] The rotation direction and rotation speed of the polishing
head 10 and the polishing pad 20 may be appropriately set according
to the film to be polished. That is, the rotation directions may be
the same as or opposite to each other. Also, the rotational speeds
may be the same as or different from each other.
[0025] In the present embodiment, the retainer ring 14 is provided
along the outer periphery of the substrate 100 held by the
polishing head 10. Therefore, even if a force for moving the
substrate 100 to the outside of the polishing head 10 is generated
with the rotation of the polishing head 10, the movement of the
substrate 100 can be blocked by the retainer ring 14. Thereby, it
is possible to prevent the substrate 100 from jumping out of the
polishing head 10.
[0026] On the other hand, the retainer ring 14 may be pressed
against the polishing pad 20 in the same manner as the substrate
100, and thus may be worn as the substrate 100 is polished.
[0027] In this embodiment, in order to reduce the wear of the
retainer ring 14 accompanying polishing of the substrate 100, the
retainer ring 14 may be formed of the first material containing a
fluororesin. The first material may contain, for example, at least
one of aromatic polyamide (PPA), polyphenylene sulfide (PPS),
polyetherimide (PEI), polyamideimide (PAI), polyetheretherketone
(PEEK), and polybenzimidazole (PBI). That is, the retainer ring 14
of the embodiment may include a plurality of types of materials
exemplified above.
[0028] Examples of the fluororesin may include at least one of
polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), a
perfluoroethylene propene copolymer (FEP), an ethylene
tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride
(PVDF), polychlorotrifluoroethylene (PCTFE), ethylene
chlorotrifluoroethylene copolymer (ECTFE),
tetrafluoroethylene-perfluorodioxole copolymer (TFE/PDD), and
polyvinyl fluoride (PVF). That is, the retainer ring 14 of the
embodiment may include a plurality of types of fluororesins
exemplified above.
[0029] It is considerable that the fluororesin is known to have a
low friction coefficient on the surface thereof, and by using it as
a material of the retainer ring 14, the friction coefficient
between the retainer ring and the polishing pad can be reduced and
the wear of the retainer ring can be reduced. Hereinafter, an
appropriate amount range of the fluororesin added to the retainer
ring 14 will be described with reference to FIGS. 4 and 5.
[0030] FIG. 4 is a graph illustrating a relationship between the
material of the retainer ring and an abrasion loss. In FIG. 4, a
horizontal axis indicates the material of the retainer ring 14 in
which the additive amount of polytetrafluoroethylene (PTFE), which
is an example of a fluororesin, is different. A vertical axis
indicates abrasion loss (.mu.m) per hour of each material.
[0031] As illustrated in FIG. 4, if PTFE is not added to a
thermoplastic engineering plastic material typified by a
polyphenylene sulfide (PPS) resin or a polyether ether ketone
(PEEK) resin, the abrasion loss of the retainer ring 14 is large.
In this case, the life of the retainer ring 14 is shortened.
[0032] On the other hand, in a case where the weight percentage
indicating the weight of PTFE with respect to the weight of the
PEEK resin is 1% to 20%, the abrasion loss of the retainer ring 14
is reduced as illustrated in FIG. 4. The reason for this is that
the frictional force generated between the retainer ring 14 and the
polishing pad 20 is alleviated by adding PTFE.
[0033] FIG. 5 is a graph illustrating a polishing rate and
uniformity of a substrate for each material of the retainer ring.
In FIG. 5, the horizontal axis indicates the material of the
retainer ring 14. The vertical axis on the left side indicates a
polishing rate which is a polishing amount (nm) per minute at the
center of the substrate 100. The vertical axis on the right side
indicates the uniformity (%), which is a variation in polishing
within the surface of the substrate 100. The polishing rate and the
uniformity are indicated for the initial (first) substrate,
50.sup.th substrate, and 100.sup.th substrate out of 100 processed
substrates 100.
[0034] As illustrated in FIG. 5, when the weight percentage of PTFE
with respect to the PEEK resin is in a range of 1% to 10%, the
polishing rate and the uniformity of the substrate 100 are as high
as that of PPS not added with PTFE. On the other hand, when the
weight percentage of PTFE exceeds 20%, the polishing rate is
decreased as the number of processed substrates 100 are increased,
and thereby the uniformity deteriorates. This is because the debris
containing PTFE added to the retainer ring 14 is attached to the
polishing pad and the abrasive grains and hinders polishing of the
substrate 100.
[0035] Therefore, in consideration of the polishing rate and the
uniformity of the substrate 100, it is desirable that the weight
percentage of the fluororesin added to the retainer ring 14 is in
the range of 1% to 10%.
[0036] According to the embodiment described above, the frictional
force generated between the retainer ring 14 and the polishing pad
20 can be reduced by adding the fluororesin to the material of the
retainer ring 14. With this, since the lifetime of the retainer
ring 14 can become long, the replacement frequency of the retainer
ring 14 can be reduced. Moreover, the polishing rate and the
uniformity of the substrate 100 can be ensured by setting the
weight percentage indicating a total weight of the fluororesin in
the range of 1% to 10%, with respect to a total weight of aromatic
polyamide (PPA), polyphenylene sulfide (PPS), polyetherimide (PEI),
polyamideimide (PAI), polyetheretherketone (PEEK), and
polybenzimidazole (PBI) which are the first materials.
[0037] In the embodiment, the retainer ring 14 is described as
including the first material and the fluororesin. However, a
material other than the first material and the fluororesin may be
included. Even in that case, the total weight of the fluororesin
with respect to the total weight of the first material may be set
to be in a range of 1% to 10 weight percent.
[0038] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the present disclosure. Indeed, the
novel embodiments described herein may be embodied in a variety of
other forms; furthermore, various omissions, substitutions and
changes in the form of the embodiments described herein may be made
without departing from the spirit of the present disclosure. The
accompanying claims and their equivalents are intended to cover
such forms or modifications as would fall within the scope and
spirit of the present disclosure.
* * * * *