U.S. patent application number 13/944357 was filed with the patent office on 2014-01-30 for roughened substrate support.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Soo Young CHOI, Dongsuh LEE, Beom Soo PARK, William N. STERLING.
Application Number | 20140027289 13/944357 |
Document ID | / |
Family ID | 49993810 |
Filed Date | 2014-01-30 |
United States Patent
Application |
20140027289 |
Kind Code |
A1 |
LEE; Dongsuh ; et
al. |
January 30, 2014 |
ROUGHENED SUBSTRATE SUPPORT
Abstract
The present invention generally relates to a substrate support
for use in a substrate processing chamber. A roughened substrate
support reduces arcing within the chamber and also contributes to
uniform deposition on the substrate. The roughening can occur in
two steps. In a first step, the substrate support is bead blasted
to initially roughen the surfaces. Then, the roughened surface is
bead blasted with a finer grit to produce a substrate support with
a surface roughness of between about 707 micro-inches and about 837
micro-inches. Following the surface roughening, the substrate
support is anodized.
Inventors: |
LEE; Dongsuh; (Santa Clara,
CA) ; STERLING; William N.; (Santa Clara, CA)
; PARK; Beom Soo; (San Jose, CA) ; CHOI; Soo
Young; (Fremont, CA) |
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Family ID: |
49993810 |
Appl. No.: |
13/944357 |
Filed: |
July 17, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61676790 |
Jul 27, 2012 |
|
|
|
Current U.S.
Class: |
205/50 ;
451/38 |
Current CPC
Class: |
C23C 16/4581 20130101;
B24C 1/00 20130101; H01L 21/68757 20130101; B24C 1/06 20130101 |
Class at
Publication: |
205/50 ;
451/38 |
International
Class: |
B24C 1/00 20060101
B24C001/00 |
Claims
1. A method of forming a roughened substrate support, comprising:
bead blasting a surface of a substrate support in a first process
where the beads have a first grit size; and bead blasting the
surface of the substrate support in a second process where the
beads have a second grit size that is smaller than the first grit
size.
2. The method of claim 1, wherein the first process comprises
delivering the beads from a nozzle to the substrate support and
wherein the nozzle is disposed at an angle of between about 85
degrees and 95 degrees relative to the surface of the substrate
support.
3. The method of claim 2, wherein the first grit size is between
about 23 grit and about 25 grit.
4. The method of claim 3, wherein the nozzle is spaced between
about 400 mm and about 600 mm from the surface of the substrate
support during the first process.
5. The method of claim 4, wherein the first process further
comprises: scanning the nozzle across the surface of the substrate
support in a first direction; shifting the nozzle along the surface
of the substrate support in a second direction perpendicular to the
first direction; and scanning the nozzle across the surface of the
substrate support in a third direction opposite the first
direction.
6. The method of claim 5, wherein the shifting comprises moving the
nozzle in the second direction for a distance between about 20 mm
and about 40 mm.
7. The method of claim 1, wherein the second process comprises
delivering the beads from a nozzle to the substrate support and
wherein the nozzle is disposed at an angle of between about 85
degrees and 95 degrees relative to the surface of the substrate
support.
8. The method of claim 7, wherein the second grit size is between
about 58 grit and about 61 grit.
9. The method of claim 8, wherein the nozzle is spaced between
about 400 mm and about 600 mm from the surface of the substrate
support during the second process.
10. The method of claim 9, wherein the second process further
comprises: scanning the nozzle across the surface of the substrate
support in a first direction; shifting the nozzle along the surface
of the substrate support in a second direction perpendicular to the
first direction; and scanning the nozzle across the surface of the
substrate support in a third direction opposite the first
direction.
11. The method of claim 10, wherein the shifting comprises moving
the nozzle in the second direction for a distance between about 20
mm and about 40 mm.
12. The method of claim 11, wherein the second process further
comprises: rotating the substrate support 90 degrees
counterclockwise; scanning the nozzle across the surface of the
substrate support in the first direction; shifting the nozzle along
the surface of the substrate support in the second direction; and
scanning the nozzle across the surface of the substrate support in
the third direction.
13. The method of claim 12, wherein the second process further
comprises: rotating the substrate support 90 degrees
counterclockwise; scanning the nozzle across the surface of the
substrate support in the first direction; shifting the nozzle along
the surface of the substrate support in the second direction; and
scanning the nozzle across the surface of the substrate support in
the third direction.
14. The method of claim 13, wherein the second process further
comprises: rotating the substrate support 90 degrees
counterclockwise; scanning the nozzle across the surface of the
substrate support in the first direction; shifting the nozzle along
the surface of the substrate support in the second direction; and
scanning the nozzle across the surface of the substrate support in
the third direction.
15. A method of forming a roughened substrate support, comprising:
bead blasting a surface of a substrate support in a first process
comprising: scanning the nozzle across the surface of the substrate
support in a first direction; shifting the nozzle along the surface
of the substrate support in a second direction perpendicular to the
first direction; and scanning the nozzle across the surface of the
substrate support in a third direction opposite the first
direction; and bead blasting the surface of the substrate support
in a second process comprising: first scanning the nozzle across
the surface of the substrate support in the first direction;
shifting the nozzle along the surface of the substrate support in
the second direction; second scanning the nozzle across the surface
of the substrate support in the third direction; rotating the
substrate support about 90 degrees counterclockwise; and repeating
the first scanning, shifting, second scanning and rotating.
16. The method of claim 15, wherein the repeating occurs three
times.
17. The method of claim 16, wherein the first process comprises
bead blasting the surface with beads having a grit size of between
about 23 grit and about 25 grit.
18. The method of claim 17, wherein the second process comprises
bead blasting the surface with beads having a grit size of between
about 58 grit and 61 grit.
19. A substrate support, comprising: a substrate support body
having a surface roughness of between about 707 micro-inches and
about 834 micro-inches; and an anodized coating on the substrate
support.
20. The substrate support of claim 19, wherein the substrate
support body comprises aluminum.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional Patent
Application Ser. No. 61/676,790 (APPM/017682L), filed Jul. 27,
2012, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention generally relate to a
substrate support for use in a substrate processing chamber.
[0004] 2. Description of the Related Art
[0005] Plasma enhanced chemical vapor deposition (PECVD) is
generally employed to deposit thin films on a substrate such as a
flat panel or semiconductor wafer. PECVD is generally accomplished
by introducing a precursor gas into a vacuum chamber that contains
a substrate. The precursor gas is typically directed through a
distribution plate situated near the top of the chamber. The
precursor gas in the chamber is energized (e.g., excited) into a
plasma by applying RF power to the chamber from one or more RF
sources coupled to the chamber. The excited gas reacts to form a
layer of material on a surface of the substrate that is positioned
on a temperature controlled substrate support.
[0006] During processing, small local variations in film thickness,
often manifesting as spots of thinner film thickness, have been
observed which may be detrimental to the device produced. It is
believed that variation is glass thickness and flatness, along with
a smooth substrate support surface, creates a local capacitance
variation in certain locations across the substrate, thereby
creating local plasma non-uniformities that leads in deposition
variations, e.g., thin spots.
[0007] Therefore, there is a need for an improved substrate
support.
SUMMARY OF THE INVENTION
[0008] The present invention generally relates to a substrate
support for use in a substrate processing chamber. A roughened
substrate support reduces arcing within the chamber and also
contributes to uniform deposition on the substrate. The roughening
can occur in two steps. In a first step, the substrate support is
bead blasted to initially roughen the surfaces. Then, the roughened
surface is bead blasted with a finer grit to produce a substrate
support with a surface roughness of between about 707 micro-inches
and about 837 micro-inches. Following the surface roughening, the
substrate support is anodized.
[0009] In one embodiment, a method of forming a roughened substrate
support comprises bead blasting a surface of a substrate support in
a first process where the beads have a first grit size and bead
blasting the surface of the substrate support in a second process
where the beads have a second grit size that is smaller than the
first grit size.
[0010] In another embodiment, a method of forming a roughened
substrate support comprises bead blasting a surface of a substrate
support in a first process. The first process comprises scanning
the nozzle across the surface of the substrate support in a first
direction, shifting the nozzle along the surface of the substrate
support in a second direction perpendicular to the first direction
and scanning the nozzle across the surface of the substrate support
in a third direction opposite the first direction. The method
further comprises bead blasting the surface of the substrate
support in a second process. The second process comprises first
scanning the nozzle across the surface of the substrate support in
the first direction, shifting the nozzle along the surface of the
substrate support in the second direction, second scanning the
nozzle across the surface of the substrate support in the third
direction, rotating the substrate support about 90 degrees
counterclockwise and repeating the first scanning, shifting, second
scanning and rotating.
[0011] In another embodiment, a substrate support comprises a
substrate support body having a surface roughness of between about
707 micro-inches and about 834 micro-inches and an anodized coating
on the substrate support.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0013] FIG. 1 is a cross sectional view of a PECVD apparatus
according to one embodiment of the invention.
[0014] FIG. 2 is a partial sectional view of a substrate support
according to one embodiment.
[0015] FIG. 3A is a schematic cross-sectional view of substrate
support after a first step of roughening according to one
embodiment.
[0016] FIG. 3B is a schematic cross-sectional view of the substrate
support of FIG. 3A after a second step of roughening according to
one embodiment.
[0017] FIG. 4 is a schematic illustration of a roughing instrument
relative to a substrate support according to one embodiment.
[0018] FIG. 5A is a schematic illustration of a substrate support
being roughened in first step according to one embodiment.
[0019] FIG. 5B-5E are schematic illustrations of the substrate
support of FIG. 5A being roughened in a second step according to
one embodiment.
[0020] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DETAILED DESCRIPTION
[0021] The present invention generally relates to a substrate
support for use in a substrate processing chamber. A roughened
substrate support reduces arcing within the chamber and also
contributes to uniform deposition on the substrate. The roughening
can occur in two steps. In a first step, the substrate support is
bead blasted to initially roughen the surfaces. Then, the roughened
surface is bead blasted with a finer grit to produce a substrate
support with a surface roughness of between about 707 micro-inches
and about 837 micro-inches. Following the surface roughening, the
substrate support is anodized.
[0022] The description herein will be made with reference to a
PECVD chamber available from AKT America, Inc., a subsidiary of
Applied Materials, Inc., Santa Clara, Calif. It is to be understood
that the embodiments herein are equally applicable to other
processing chambers as well, including processing chamber sold by
other manufacturers.
[0023] FIG. 1 is a cross sectional view of a PECVD apparatus that
may utilize the substrate support described herein. The apparatus
includes a chamber 100 in which one or more films may be deposited
onto a substrate 120. The chamber 100 generally includes walls 102,
a bottom 104 and a showerhead 106 which define a process volume. A
substrate support 118 is disposed within the process volume. The
process volume is accessed through a slit valve opening 108 such
that the substrate 120 may be transferred in and out of the chamber
100. The substrate support 118 may be coupled to an actuator 116 to
raise and lower the substrate support 118. Lift pins 122 are
moveably disposed through the substrate support 118 to move a
substrate to and from the substrate receiving surface. The
substrate support 118 may also include heating and/or cooling
elements 124 to maintain the substrate support 118 at a desired
temperature. The substrate support 118 may also include RF return
straps 126 to provide an RF return path at the periphery of the
substrate support 118.
[0024] The showerhead 106 is coupled to a backing plate 112 by a
fastening mechanism 150. The showerhead 106 may be coupled to the
backing plate 112 by one or more fastening mechanisms 150 to help
prevent sag and/or control the straightness/curvature of the
showerhead 106.
[0025] A gas source 132 is coupled to the backing plate 112 to
provide gas through gas passages in the showerhead 106 to a
processing area between the showerhead 106 and the substrate 120. A
vacuum pump 110 is coupled to the chamber 100 to control the
process volume at a desired pressure. An RF source 128 is coupled
through a match network 190 to the backing plate 112 and/or to the
showerhead 106 to provide an RF current to the showerhead 106. The
RF current creates an electric field between the showerhead 106 and
the substrate support 118 so that a plasma may be generated from
the gases between the showerhead 106 and the substrate support
118.
[0026] A remote plasma source 130, such as an inductively coupled
remote plasma source 130, may also be coupled between the gas
source 132 and the backing plate 112. Between processing
substrates, a cleaning gas may be provided to the remote plasma
source 130 so that a remote plasma is generated. The radicals from
the remote plasma may be provided to chamber 100 to clean chamber
100 components. The cleaning gas may be further excited by the RF
source 128 provided to the showerhead 106.
[0027] The showerhead 106 may additionally be coupled to the
backing plate 112 by showerhead suspension 134. In one embodiment,
the showerhead suspension 134 is a flexible metal skirt. The
showerhead suspension 134 may have a lip 136 upon which the
showerhead 106 may rest. The backing plate 112 may rest on an upper
surface of a ledge 114 coupled with the chamber walls 102 to seal
the chamber 100.
[0028] FIG. 2 is a partial sectional view of the substrate support
118. The substrate support 118 includes a body 202 substantially
covered with an anodized coating 210. The body 202 may be comprised
of one or more coupled members or a unitary casted body having the
heating and/or cooling elements 124 embedded therein. In one
embodiment, the body 202 may comprise aluminum.
[0029] The body 202 generally includes a substrate support surface
204 and an opposing mounting surface 206. The anodized coating 210
covers at least the support surface 204 of the body 202 and
provides a separating layer between the substrate 120 and the
support surface 204.
[0030] The coating 210 includes an outer surface 212 and an inner
surface 214. The inner surface 214 is generally disposed directly
on the body 202. In one embodiment, the anodized coating has a
thickness of between about 23 .mu.m to about 27 .mu.m, such as
about 25 .mu.m. The inner surface 214 has a surface roughness that
translates to the anodized coating 210. A portion 218 of the outer
surface 212 positioned above the substrate support surface 204 has
a geometry configured to support the substrate 120 thereon. The
portion 218 of the outer surface 212 has a surface finish 216 of a
predefined roughness that promotes uniform thickness of films
deposited on the substrate 140. The surface finish 216 has a
roughness of about 707 micro-inches to about 847 micro-inches, such
as about 777 micro-inches. The surface finish 216 advantageously
results in improved film thickness uniformity.
[0031] The surface finish 216 of the anodized coating 210 may be
achieved by treating at least a portion 220 of the outer substrate
support surface 204 underlying the substrate 140 as will be
discussed below. The surface finish 208 of the substrate support
surface 204 may be formed in a number of manners, including bead
blasting, abrasive blasting, grinding, embossing, sanding,
texturing, etching or other method for providing a pre-defined
surface roughness. In one embodiment, the surface finish 208 of the
support surface 204 of the body 202 is about 707 micro-inches to
about 847 micro-inches, such as about 777 micro-inches.
[0032] Optionally, a strip 224 of the support surface 204 bounding
the portion 220 positioned out from under the substrate 120 may be
left untreated to minimize the fabrication costs. This results in a
strip 222 of the anodized coating 210 above the untreated strip 224
that may have a finish different than the finish 216, but as the
strip 222 is beyond the substrate 120, the surface finish of the
strip 222 has no effect on film deposition uniformity. In one
embodiment, the strip 222 of the anodized coating 210 has a
smoother surface finish than the portion 218 of the coating 210 it
bounds.
[0033] In order to roughen the substrate support 118, a two step
process may occur. FIG. 3A is a schematic cross-sectional view of
substrate support 118 after a first step of roughening according to
one embodiment. In the first step of the process, the substrate
support is exposed to a first bead blasting process to form valleys
302 within the substrate support 118 separated by plateaus 304. The
bead blasting may occur by exposing the substrate support 118 to
beads ejected from a nozzle 402.
[0034] FIG. 4 is a schematic illustration of a roughing instrument
(e.g., nozzle 402) relative to a substrate support 118 according to
one embodiment. The nozzle 402 may be disposed at an angle .alpha.
relative to the surface of the substrate support 118 that is being
bead blasted. The angle .alpha. may be between about 85 degrees and
about 95 degrees, for example, 90 degrees. The nozzle 402 may be
spaced from the substrate support 118 by a distance "A" of between
about 400 mm and about 600 mm. The beads for the bead blasting may
have a first grit size of between about 23 grit and about 25 grit,
for example 24 grit. The beads used are spherical beads.
[0035] In operation, the nozzle 402 scans over the substrate
support 118, however, it is contemplated that the substrate support
118 can move relative to the nozzle 402 or both the nozzle 402 and
substrate support 118 may move. FIG. 5A is a schematic illustration
of the substrate support 118 being roughened in first step
according to one embodiment. As shown, the substrate support 118
has is has a generally rectangular shape such that four sides
501-504 are present.
[0036] The nozzle 402 moves laterally as shown by arrows "E" and
scans across the surface 505 of the substrate support 118 in a
first direction from a first side 501 to a second side 502 as shown
by arrow "B". Thereafter, the nozzle 402 shifts in a second
direction that is perpendicular to the first direction as shown by
arrow "C". The nozzle 402 then ejects the beads towards the surface
505 as the nozzle 402 moves in a third direction opposite the first
direction from second side 502 to first side 501 as shown by arrow
"D". The nozzle 402 then shifts again in the second direction as
shown by arrow "C". When the nozzle 402 shifts, the nozzle shifts a
distance of between about 20 mm and about 40 mm. Thus, the nozzle
402 follows a serpentine pattern to expose the entire surface 505
to bead blasting.
[0037] Following the first bead blasting process, the substrate
support 118 is roughened as shown in FIG. 3A, but the surface 505
is not sufficiently rough. Additionally, during substrate 120
placement onto the substrate support 118 and during processing, gas
may be trapped within the valleys 302 and be unable to escape
because the plateaus 304 contact the substrate 120 and prevent gas
from escaping the valleys 302. Therefore, the substrate support 118
is bead blasted in a second process to roughen the plateaus 304 and
further roughen the valleys 302. FIG. 3B is a schematic
cross-sectional view of the substrate support 118 of FIG. 3A after
a second step of roughening according to one embodiment. As shown
in FIG. 3B, the plateaus 304 are no longer present, but rather, a
roughened surface 306 is present. Following the second bead
blasting process, the surface roughness of the substrate support
118 may be between about 707 micro-inches and about 837
micro-inches, for example 777 micro-inches. Because a grit size of
between about 58 grit and about 61 grit, such as 60 grit, is
utilized, rough peaks/edges on the substrate support 118 are few
and far between. Peaks/edges are sharp points where the substrate
120 will contact the substrate support 118 and can lead to arcing
between the substrate 120 and substrate support 118, as well as
scratching of the substrate 120. Additionally, due to the uneven
surface and lack of plateaus, gas that may otherwise be trapped
between the substrate support 118 and substrate 120 may freely be
evacuated from between the substrate support 118 and substrate 120.
The beads used are spherical beads.
[0038] FIG. 5B-5E are schematic illustrations of the substrate
support 118 of FIG. 5A being roughened in the second process
according to one embodiment. The second process spaces the nozzle
402 from the substrate support 118 by the same distance and at the
same angle as in the first process. The second process has four
separate steps in the case of a rectangular shaped substrate
support 118.
[0039] In the first step of the second process, shown in FIG. 5B,
the nozzle 402 scans across the substrate support 118 in a manner
similar to the first process. Namely, the nozzle 402 scans in the
first direction from the first side 501 to the second side 502 as
shown by arrow "B". Then, the nozzle shifts as shown by arrows "C"
in the second direction towards the third side 503. Thereafter, the
nozzle scans in the third direction from the second side 502 to the
first side 501 as shown by arrows "D". The nozzle 402 then shifts
again in the second direction as shown by arrows "C". When the
nozzle 402 shifts, the nozzle shifts a distance of between about 20
mm and about 40 mm. Thus, the nozzle 402 follows a serpentine
pattern to expose the entire surface 505 to bead blasting.
[0040] In the second step, shown in FIG. 5C, the substrate support
118 is rotated counterclockwise about 90 degrees. It is to be
understood that rather than counterclockwise, the substrate support
118 may be rotated clockwise. Following the rotation, the nozzle
402 scans in the first direction from a fourth side 504 to the
third side 503 as shown by arrow "B". Then, the nozzle shifts as
shown by arrows "C" in the second direction towards the first side
501. Thereafter, the nozzle scans in the third direction from the
third side 503 to the fourth side 504 as shown by arrows "D". The
nozzle 402 then shifts again in the second direction as shown by
arrows "C". When the nozzle 402 shifts, the nozzle shifts a
distance of between about 20 mm and about 40 mm. Thus, the nozzle
402 follows a serpentine pattern to expose the entire surface 505
to bead blasting.
[0041] In the third step, shown in FIG. 5D, the substrate support
118 is rotated counterclockwise about 90 degrees. It is to be
understood that rather than counterclockwise, the substrate support
118 may be rotated clockwise so long as the rotation for the third
step is in the same direction as in the second step. Following the
rotation, the nozzle 402 scans in the first direction from the
second side 502 to the first side 501 as shown by arrow "B". Then,
the nozzle shifts as shown by arrows "C" in the second direction
towards the fourth side 504. Thereafter, the nozzle scans in the
third direction from the first side 501 to the second side 502 as
shown by arrows "D". The nozzle 402 then shifts again in the second
direction as shown by arrows "C". When the nozzle 402 shifts, the
nozzle shifts a distance of between about 20 mm and about 40 mm.
Thus, the nozzle 402 follows a serpentine pattern to expose the
entire surface 505 to bead blasting.
[0042] In the fourth step, shown in FIG. 5E, the substrate support
118 is rotated counterclockwise about 90 degrees. It is to be
understood that rather than counterclockwise, the substrate support
118 may be rotated clockwise so long as the rotation for the third
step is in the same direction as in the second step. Following the
rotation, the nozzle 402 scans in the first direction from the
third side 503 to the fourth side 504 as shown by arrow "B". Then,
the nozzle shifts as shown by arrows "C" in the second direction
towards the second side 502. Thereafter, the nozzle scans in the
third direction from the fourth side 504 to the third side 503 as
shown by arrows "D". The nozzle 402 then shifts again in the second
direction as shown by arrows "C". When the nozzle 402 shifts, the
nozzle shifts a distance of between about 20 mm and about 40 mm.
Thus, the nozzle 402 follows a serpentine pattern to expose the
entire surface 505 to bead blasting.
[0043] Now that the second bead blasting process is complete, the
substrate support 118 has a surface 505 with a roughness of between
about 707 micro-inches to about 837 micro-inches, for example 777
micro-inches. Following the bead blasting process, the substrate
support 118 is anodized to form an anodized coating 210 thereover
to a thickness of between about 23 .mu.m to about 27 .mu.m, for
example, 25 .mu.m.
[0044] The roughened substrate support 118 reduces or eliminates
arcing between the substrate support 118 and the substrate 120.
Additionally, the roughened substrate support 118 reduces or
eliminates thin spots during the deposition onto the substrate 120
such that a substantially uniformly thick layer may be deposited
onto the substrate 120. Even though the substrate support 118 is
roughened, the substrate support 118 does not substantially scratch
the substrate.
[0045] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *