U.S. patent application number 13/524859 was filed with the patent office on 2015-06-11 for wafer processing deposition shielding components.
This patent application is currently assigned to APPLIED MATERIALS, INC.. The applicant listed for this patent is Keith A. Miller, Martin Lee Riker, Anantha Subramani. Invention is credited to Keith A. Miller, Martin Lee Riker, Anantha Subramani.
Application Number | 20150162171 13/524859 |
Document ID | / |
Family ID | 49754878 |
Filed Date | 2015-06-11 |
United States Patent
Application |
20150162171 |
Kind Code |
A9 |
Riker; Martin Lee ; et
al. |
June 11, 2015 |
WAFER PROCESSING DEPOSITION SHIELDING COMPONENTS
Abstract
Embodiments described herein generally relate to components for
a semiconductor processing chamber, a process kit for a
semiconductor processing chamber, and a semiconductor processing
chamber having a process kit. In one embodiment a lower shield for
encircling a sputtering target and a substrate support is provided.
The lower shield comprises a cylindrical outer band having a first
diameter dimensioned to encircle the sputtering surface of the
sputtering target and the substrate support, the cylindrical band
comprising a top wall that surrounds a sputtering surface of a
sputtering target and a bottom wall that surrounds the substrate
support, a support ledge comprising a resting surface and extending
radially outward from the cylindrical outer band, a base plate
extending radially inward from the bottom wall of the cylindrical
band, and a cylindrical inner band coupled with the base plate and
partially surrounding a peripheral edge of the substrate
support.
Inventors: |
Riker; Martin Lee;
(Milpitas, CA) ; Miller; Keith A.; (Mountain View,
CA) ; Subramani; Anantha; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Riker; Martin Lee
Miller; Keith A.
Subramani; Anantha |
Milpitas
Mountain View
San Jose |
CA
CA
CA |
US
US
US |
|
|
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20130334038 A1 |
December 19, 2013 |
|
|
Family ID: |
49754878 |
Appl. No.: |
13/524859 |
Filed: |
June 15, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12423444 |
Apr 14, 2009 |
|
|
|
13524859 |
|
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|
61045556 |
Apr 16, 2008 |
|
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61049334 |
Apr 30, 2008 |
|
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Current U.S.
Class: |
204/298.11 |
Current CPC
Class: |
H01J 37/3441 20130101;
H01J 37/32651 20130101; H01J 37/3405 20130101; C23C 14/564
20130101 |
International
Class: |
H01J 37/32 20060101
H01J037/32; C23C 14/34 20060101 C23C014/34 |
Claims
1. A lower shield for encircling a sputtering target and a
substrate support in a substrate processing chamber, the processing
having a chamber body having a tapered inside surface, the lower
shield comprising: a cylindrical outer band having a first diameter
dimensioned to encircle the sputtering surface of the sputtering
target and the substrate support, the cylindrical band comprising:
a plurality of gas holes; a bottom wall configured to surround the
substrate support, the bottom wall comprising a notch; and a top
wall configured to surround a sputtering surface of the sputtering
target, the top wall comprising: an inner periphery facing inward
and angled radially inward from vertical towards the bottom wall;
and an outer periphery facing outward, wherein the outer periphery
extends to form a sloped step and the sloped step is configured to
engage with the tapered inside surface of the chamber body, wherein
the sloped step is angled radially outward from vertical and away
from the bottom wall; a support ledge comprising a resting surface
and extending radially outward from the cylindrical outer band, the
resting surface having a surface roughness of from about 10 to
about 80 microinches and a plurality of slots; a base plate
extending radially inward from the bottom wall of the cylindrical
band; and a cylindrical inner band coupled with the base plate and
configured to partially surround a peripheral edge of the substrate
support.
2. The lower shield of claim 1, wherein the sloped step is angled
radially outward between about 5 degrees and about 10 degrees from
vertical.
3. The lower shield of claim 2, wherein the inner periphery is
angled radially inward between about 2 degrees and about 5 degrees
from vertical.
4. The lower shield of claim 1, wherein the cylindrical inner band,
the base plate, and the cylindrical outer band form a U-shaped
channel.
5. The lower shield of claim 4, wherein the cylindrical inner band
comprises a height that is less than the height of the cylindrical
outer band.
6. The shield of claim 5, wherein the height of the cylindrical
inner band is about one fifth of the height of the cylindrical
outer band.
7. The lower shield of claim 1, wherein the bottom wall has a
notch.
8. The lower shield of claim 1, wherein the cylindrical outer band,
the top wall, the support ledge, the bottom wall, and the inner
cylindrical band comprise a unitary structure.
9. The lower shield of claim 1, wherein exposed surfaces of the
lower shield are bead blasted to have a surface roughness of
175.+-.75 microinches.
10. The lower shield of claim 1, further comprising a twin-wire
aluminum arc spray coating on a surface of the lower shield wherein
the twin-wire aluminum arc spray coating comprise a surface
roughness from about 600 to about 2300 microinches.
11. A lower shield for encircling a sputtering target and a
substrate support in a substrate processing chamber, the processing
having a chamber body having a tapered inside surface, the lower
shield comprising: a cylindrical outer band having a first diameter
dimensioned to encircle the sputtering surface of the sputtering
target and the substrate support, the cylindrical band comprising:
a plurality of gas holes; a bottom wall configured to surround the
substrate support, the bottom wall comprising a notch; and a top
wall configured to surround a sputtering surface of the sputtering
target, the top wall comprising: an inner periphery facing inward
and angled radially inward between about 2 degrees and about 5
degrees from vertical towards the bottom wall; and an outer
periphery facing outward, wherein the outer periphery extends to
form a sloped step and the sloped step is configured to engage with
the tapered inside surface of the chamber body, wherein the sloped
step is angled radially outward between about 5 degrees and about
10 degrees from vertical and away from the bottom wall; a support
ledge comprising a resting surface and extending radially outward
from the cylindrical outer band, the resting surface having a
surface roughness of from about 10 to about 80 microinches and a
plurality of slots; a base plate extending radially inward from the
bottom wall of the cylindrical band; and a cylindrical inner band
coupled with the base plate and configured to partially surround a
peripheral edge of the substrate support, wherein the cylindrical
inner band has a height that is less than a height of the
cylindrical outer band, wherein the cylindrical outer band, the top
wall, the support ledge, the bottom wall, and the inner cylindrical
band comprise a unitary structure, and wherein exposed surfaces of
the lower shield are bead blasted to have a surface roughness of
175.+-.75 microinches.
12. The lower shield of claim 11, further comprising a twin-wire
aluminum arc spray coating on a surface of the lower shield wherein
the twin-wire aluminum arc spray coating comprise a surface
roughness from about 600 to about 2300 microinches.
13. The lower shield of claim 11, wherein the cylindrical inner
band, the base plate, and the cylindrical outer band form a
U-shaped channel.
14. The lower shield of claim 11, wherein the bottom wall has a
notch.
15. The lower shield of claim 11, wherein the sloped step is angled
radially outward about 8 degrees from vertical.
16. The lower shield of claim 15, wherein the inner periphery is
angled radially inward about 3.5 degrees from vertical.
17. The lower shield of claim 11, wherein the cylindrical inner
band has a height that is one fifth of the height of the
cylindrical outer band.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. patent application
Ser. No. 12/423,444, filed Apr. 14, 2009, which claims benefit of
U.S. Provisional Patent Application Ser. No. 61/045,556, filed Apr.
16, 2008, and U.S. Provisional Patent Application Ser. No.
61/049,334, filed Apr. 30, 2008, all of which are herein
incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments described herein generally relate to components
for a semiconductor processing chamber, a process kit for a
semiconductor processing chamber, and a semiconductor processing
chamber having a process kit. More specifically, embodiments
described herein relate to a process kit that includes a ring
assembly and multiple shields suitable for use in a physical vapor
deposition chamber.
[0004] 2. Description of the Related Art
[0005] In the manufacture of integrated circuits and displays, a
substrate such as a semiconductor wafer or display panel, is placed
in a substrate processing chamber and processing conditions are set
in the chamber to deposit or etch material on the substrate. A
typical process chamber comprises chamber components that include
an enclosure wall that encloses a process zone, a gas supply to
provide a process gas in the chamber, a gas energizer to energize
the process gas to process the substrate, a gas exhaust to remove
spent gas and maintain a gas pressure in the chamber, and a
substrate support to hold the substrate. Such chambers can include,
for example, sputtering (PVD), chemical vapor deposition (CVD), and
etching chambers. In PVD chambers, a target is sputtered by
energized gas to sputter target material which then deposits on the
substrate facing the target.
[0006] In sputtering processes, the material sputtered from the
target also deposits on the edges of chamber components surrounding
the target which is undesirable. The peripheral target regions have
a dark-space region in which sputtered material redeposit as a
result of ion scattering in this area. Accumulation and build-up of
the sputtered material in this region is undesirable as such
accumulated deposits require disassembly and cleaning or
replacement of the target and surrounding components, can result in
plasma shorting, and can cause arcing between the target and the
chamber wall. These deposits also often debond and flake off due to
thermal stresses to fall inside and contaminate the chamber and its
components.
[0007] A process kit comprising a shield, cover ring and deposition
ring arranged about the substrate support and chamber sidewalls, is
often used to receive the excess sputtered material to protect and
prevent deposition on the chamber walls and other component
surfaces. Periodically, the process kit components are dismantled
and removed from the chamber for cleaning off accumulated deposits.
Thus it is desirable to have process kit components which are
designed to receive and tolerate ever larger amounts of accumulated
deposits without sticking to each other or to the substrate, or
resulting in flaking off of the deposits between process clean
cycles. It is further desirable to have a process kit comprising
fewer parts or components, as well as having components that are
shaped and arranged in relationship to one another to reduce the
amounts of sputtered deposits formed on the internal surfaces of
the process chamber.
[0008] Another problem arises when the chamber liners and shields
heat up to excessively high temperatures due to exposure to the
sputtering plasma in the chamber and poor thermal conductivity
between the shield and chamber components. For example, it is
difficult to control the temperature of shields made of low thermal
conductivity material. The thermal resistances at contact
interfaces with supporting components, such as adapters, also
affect shield temperatures. Low clamping forces between the shield
and adapter can also give rise to heating up of the shield. Without
thermal control, the temperature of the shields cycles between idle
room-temperature conditions and high temperatures during sequential
substrate processing. When process deposits of high-stress metal
are deposited onto the shields and subjected to large temperature
swings, the adhesion of the film to the shield as well as the
cohesion of the film to itself, can decrease dramatically due to,
for example, a mismatch of the coefficients of thermal expansion
between the film and the underlying shield. It is desirable to
reduce the temperatures of shields and liners during substrate
processing to reduce flaking of accumulated deposits from the
shield surfaces.
[0009] Another problem with conventional substrate processing
chamber and PVD processes arises due to poor gas conductance from
the chamber. A high-conductance gas flow pathway is needed to both
supply the necessary process gasses to the process cavity and to
properly exhaust spent process gas. However, the shields and other
chamber components of the process kit that line the chamber walls
can substantially reduce gas conductance flows. Placing apertures
in these components while increasing gas conductance therethrough,
also allow line-of-sight sputtering deposits to exit the process
zone through the gas conductance holes to deposit on the chamber
walls. Such holes can also cause plasma leakage from within the
processing cavity to surrounding chamber regions. Also, chamber
components that incorporate such holes have other shortcomings
including, but not limited to, requirement of additional parts,
their relative flimsiness, tolerance stack-ups of multiple parts,
and poor thermal conductivity at interfaces.
[0010] Thus it is desirable to have process kit components that
increase thermal conductivity while reducing the flaking of process
deposits from component surfaces. It is further desirable to
control the temperature of the shields and liners so that they do
not cycle between excessively high and low temperatures during
plasma processing. It is also desirable to increase overall gas
conductance while preventing line-of-sight deposition outside the
process zone and reduce plasma leakage.
SUMMARY OF THE INVENTION
[0011] Embodiments described herein generally relate to components
for a semiconductor processing chamber, a process kit for a
semiconductor processing chamber, and a semiconductor processing
chamber having a process kit. In one embodiment a lower shield for
encircling a sputtering target and a substrate support is provided.
The lower shield comprises a cylindrical outer band having a first
diameter dimensioned to encircle the sputtering surface of the
sputtering target and the substrate support, the cylindrical band
comprising a top wall that surrounds a sputtering surface of a
sputtering target and a bottom wall that surrounds the substrate
support, a support ledge comprising a resting surface and extending
radially outward from the cylindrical outer band, a base plate
extending radially inward from the bottom wall of the cylindrical
band, and a cylindrical inner band coupled with the base plate and
partially surrounding a peripheral edge of the substrate
support.
[0012] In another embodiment, a deposition ring for encircling a
peripheral wall of a substrate support in a processing chamber is
provided. The deposition ring comprises an annular band for
surrounding the peripheral wall of the substrate support, the
annular band comprising an inner lip which extends transversely
from the annular band and is substantially parallel to the
peripheral wall of the substrate support, wherein the inner lip
defines an inner perimeter of the deposition ring which surrounds
the periphery of the substrate and substrate support to protect
regions of the support that are not covered by the substrate during
processing to reduce or even entirely preclude deposition of
sputtering deposits on the peripheral wall, and a v-shaped
protuberance that extends along a central portion of the band with
a first radially inward recess adjacent to the inner lip and a
second radially inward recess on either side of the v-shaped
protuberance.
[0013] In yet another embodiment, a cover ring for encircling and
at least partially shadowing a deposition ring from sputtering
deposits is provided. The deposition ring comprises an annular
wedge comprising a top surface, an inclined top surface sloped
radially inward and coupled with the top surface having an inner
periphery and an outer periphery, a bottom surface to rest upon a
ledge of a deposition ring, wherein the top surface is
substantially parallel to the bottom surface, and a projecting brim
coupled with the top surface by the inclined top surface in
cooperation with the projecting brim block line-of-sight deposition
from exiting the interior volume and entering the chamber body
cavity, and an inner cylindrical band extending downward from the
annular wedge, the inner cylindrical band having a smaller height
than the outer cylindrical band.
[0014] In yet another embodiment a process kit for a semiconductor
processing chamber is provided. The process kit comprises a lower
shield, a middle shield, and a ring assembly positioned about a
substrate support in a processing chamber to reduce deposition of
process deposits on the internal chamber components and an
overhanging edge of the substrate is provided. The lower shield
comprises an outer cylindrical band having a top wall that
surrounds a sputtering target and a bottom wall that surrounds the
substrate support, a support ledge, and an inner cylindrical band
surrounding the substrate support. The ring assembly comprises a
deposition ring and a cover ring.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] 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.
[0016] FIG. 1 is a simplified sectional view of a semiconductor
processing system having one embodiment of a process kit described
herein;
[0017] FIG. 2 is a partial sectional view of a process kit
interfaced with a target and adapter of FIG. 1;
[0018] FIG. 3A is a cross-sectional view of a lower shield
according to one embodiment described herein;
[0019] FIG. 3B is a partial sectional view of the lower shield of
FIG. 3A;
[0020] FIG. 3C is a top view of the lower shield of FIG. 3A;
[0021] FIG. 4A is a cross-sectional view of a deposition ring
according to one embodiment described herein;
[0022] FIG. 4B is a partial sectional view of the deposition ring
according to one embodiment described herein;
[0023] FIG. 4C is a top view of the deposition ring of FIG. 4A;
[0024] FIG. 5A is a partial section view of a middle shield
according to one embodiment described herein;
[0025] FIG. 5B is a top view of the middle shield of FIG. 5A;
[0026] FIG. 6A is a partial sectional view of a cover ring
according to one embodiment described herein;
[0027] FIG. 6B is a cross-sectional view of the cover ring of FIG.
6A; and
[0028] FIG. 6C is a top view of the cover ring of FIG. 6A.
DETAILED DESCRIPTION
[0029] Embodiments described herein generally provide a process kit
for use in a physical deposition chamber (PVD) chamber. The process
kit has advantageously provided a reduction in RF harmonics and
stray plasma outside the process cavity, which promotes greater
process uniformity and repeatability along with longer chamber
component service life.
[0030] FIG. 1 depicts an exemplary semiconductor processing chamber
100 having one embodiment of a process kit 150 capable of
processing a substrate 105. The process kit 150 includes a
one-piece lower shield 160, an interleaving cover ring 170, a
deposition ring 180, and a middle shield 190. In the embodiment
shown, the processing chamber 100 comprises a sputtering chamber,
also called a physical deposition or PVD chamber, capable of
depositing titanium, aluminum oxide, aluminum, copper, tantalum,
tantalum nitride, tungsten, or tungsten nitride on a substrate.
Examples of suitable PVD chambers include the ALPS.RTM. Plus and
SIP ENCORE.RTM. PVD processing chambers, both commercially
available from Applied Materials, Inc., Santa Clara, of California.
It is contemplated that processing chambers available from other
manufactures may also be utilized to perform the embodiments
described herein.
[0031] The processing chamber 100 includes a chamber body 101
having enclosure walls 102 and sidewalls 104, a bottom wall 106,
and a lid assembly 108 that enclose an interior volume 110 or
plasma zone. The chamber body 101 is typically fabricated from
welded plates of stainless steel or a unitary block of aluminum.
The sidewalls 104 generally contain a slit valve (not shown) to
provide for entry and egress of a substrate 105 from the processing
chamber 100. A pumping port 120 disposed in the sidewalls 104 is
coupled to a pumping system 122 that exhausts and controls the
pressure of the interior volume 110. The lid assembly 108 of the
processing chamber 100 works in cooperation with the lower shield
160 that interleaves with the cover ring 170, the middle shield
190, and an upper shield 195 to confine a plasma formed in the
interior volume 110 to the region above the substrate.
[0032] A pedestal assembly 124 is supported from the bottom wall
106 of the chamber 100. The pedestal assembly 124 supports the
deposition ring 180 along with the substrate 105 during processing.
The pedestal assembly 124 is coupled to the bottom wall 106 of the
chamber 100 by a lift mechanism 126 that is configured to move the
pedestal assembly 124 between an upper and lower position.
Additionally, in the lower position, lift pins may be moved through
the pedestal assembly 124 to space the substrate 105 from the
pedestal assembly 124 to facilitate exchange of the substrate 105
with a wafer transfer mechanism disposed exterior to the processing
chamber 100, such as a single blade robot (not shown). A bellows
129 is typically disposed between the pedestal assembly 124 and the
chamber bottom wall 106 to isolate the interior volume 110 of the
chamber body 101 from the interior of the pedestal assembly 124 and
the exterior of the chamber.
[0033] The pedestal assembly 124 generally includes a substrate
support 128 sealingly coupled to a platform housing 130. The
platform housing 130 is typically fabricated from a metallic
material such as stainless steel or aluminum. A cooling plate (not
shown) is generally disposed within the platform housing 130 to
thermally regulate the substrate support 128. One pedestal assembly
124 that may be adapted to benefit from the invention is described
in U.S. Pat. No. 5,507,499, issued Apr. 16, 1996 to Davenport et
al., which is incorporated herein by reference in its entirety.
[0034] The substrate support 128 may be comprised of aluminum or
ceramic. The substrate support 128 has a substrate receiving
surface 132 that receives and supports the substrate 105 during
processing, the substrate receiving surface 132 having a plane
substantially parallel to a sputtering surface 134 of a sputtering
target 136. The support 128 also has a peripheral wall 138 that
terminates before an overhanging edge 107 of the substrate 105. The
substrate support 128 may be an electrostatic chuck, a ceramic
body, a heater or a combination thereof. In one embodiment, the
substrate support 128 is an electrostatic chuck that includes a
dielectric body having a conductive layer embedded therein. The
dielectric body is typically fabricated from a high thermal
conductivity dielectric material such as pyrolytic boron nitride,
aluminum nitride, silicon nitride, alumina or an equivalent
material.
[0035] The lid assembly 108 generally includes the target 136 and a
magnetron 140. The lid assembly 108 is supported by the sidewalls
104 when in a closed position, as shown in FIG. 1. An isolator ring
142 is disposed between the target 136 and the upper shield 195 to
prevent vacuum leakage therebetween and reduce electrical shorts
between the chamber walls and the target 136. In one embodiment the
upper shield 195 comprises a material such as aluminum or stainless
steel.
[0036] The target 136 is coupled to the lid assembly 108 and
exposed to the interior volume 110 of the processing chamber 100.
The target 136 provides material which is deposited on the
substrate during a PVD process. The isolator ring 142 is disposed
between the target 136 and chamber body 101 to electrically isolate
the target 136 from the chamber body 101. In one embodiment, the
isolator ring 142 comprises a ceramic material.
[0037] The target 136 and pedestal assembly 124 are biased relative
to each other by a power source 144. A gas, such as argon, is
supplied to the interior volume 110 from a gas source 146 via
conduits 148. The gas source 146 may comprise a non-reactive gas
such as argon or xenon, which is capable of energetically impinging
upon and sputtering material from the target 136. The gas source
146 may also include a reactive gas, such as one or more of an
oxygen-containing gas and a nitrogen-containing gas, that are
capable of reacting with the sputtering material to form a layer on
a substrate. Spent process gas and byproducts are exhausted from
the chamber 100 through pumping port 120 that receive spent process
gas and pass the spent process gas to an exhaust conduit 121 having
a throttle valve to control the pressure of the gas in the chamber
100. The exhaust conduit 148 is connected to the pumping system
122. Typically, the pressure of the sputtering gas in the chamber
100 is set to sub-atmospheric levels, such as a vacuum environment,
for example, gas pressures of 1 mTorr to 400 mTorr. Plasma is
formed between the substrate 105 and the target 136 from the gas.
Ions within the plasma are accelerated toward the target 136 and
cause material to become dislodged from the target 136. The
dislodged target material is deposited on the substrate 105.
[0038] The magnetron 140 is coupled to the lid assembly 108 on the
exterior of the processing chamber 100. The magnetron 140 includes
at least one rotating magnet assembly (not shown) that promotes
uniform consumption of the target 136 during the PVD process. One
magnetron which may be utilized is described in U.S. Pat. No.
5,953,827, issued Sep. 21, 1999 to Or et al., which is hereby
incorporated by reference in its entirety.
[0039] The chamber 100 is controlled by a controller 196 that
comprises program code having instruction sets to operate
components of the chamber 100 to process substrates in the chamber
100. For example, the controller 196 can comprise program code that
includes a substrate positioning instruction set to operate the
substrate support 128; a gas flow control instruction set to
operate gas flow control valves to set a flow of sputtering gas to
the chamber 100; a gas pressure control instruction set to operate
a throttle valve to maintain a pressure in the chamber 100; a
temperature control instruction set to control a temperature
control system (not shown) in the support 128 or sidewall 104 to
set temperatures of the substrate or sidewalls 104, respectively;
and a process monitoring instruction set to monitor the process in
the chamber 100.
[0040] A collimator 197 is coupled with the lower shield 160,
thereby grounding the collimator. In one embodiment, the collimator
may be a metal ring and includes an outer tubular section and at
least one inner concentric tubular section, for example, three
concentric tubular sections linked by struts.
[0041] The chamber 100 also contains a process kit 150 which
comprises various components that can be easily removed from the
chamber 100, for example, to clean sputtering deposits off the
component surfaces, replace or repair eroded components, or to
adapt the chamber 100 for other processes. In one embodiment, the
process kit 150 comprises a lower shield 160, a middle shield 190,
and a ring assembly 202 for placement about a peripheral wall 138
of the substrate support 128 that terminates before an overhanging
edge 107 of the substrate 105. As shown in FIG. 2, the ring
assembly 202 comprises the deposition ring 180 and the cover ring
170. The deposition ring 180 comprises an annular band 402
surrounding the support 128. The cover ring 170 at least partially
covers the deposition ring 180. The deposition ring 180 and the
cover ring 170 cooperate with one another to reduce formation of
sputter deposits on the peripheral wall 138 of the support 128 and
the overhanging edge 107 of the substrate 105.
[0042] The lower shield 160 encircles the sputtering surface 134 of
the sputtering target 136 that faces the substrate support 128 and
the peripheral wall 138 of the substrate support 128. The lower
shield 160 covers and shadows the sidewalls 104 of the chamber 100
to reduce deposition of sputtering deposits originating from the
sputtering surface 134 of the sputtering target 136 onto the
components and surfaces behind the lower shield 160. For example,
the lower shield 160 can protect the surfaces of the support 128,
the overhanging edge 107 of the substrate 105, sidewalls 104 and
bottom wall 106 of the chamber 100.
[0043] FIGS. 3A and 3B are partial sectional views of a lower
shield according to one embodiment described herein. FIG. 3C is a
top view of the lower shield of FIG. 3A. As shown in FIG. 1 and
FIGS. 3A-3C, the lower shield 160 is of unitary construction and
comprises a cylindrical outer band 310 having a diameter
dimensioned to encircle the sputtering surface 134 of the
sputtering target 136 and the substrate support 128. The
cylindrical outer band 310 has a top wall 312 that surrounds the
sputtering surface 134 of the sputtering target 136. A support
ledge 313 extends radially outward from the top wall 312 of the
cylindrical outer band 310. The support ledge 313 comprises a
resting surface 314 to rest upon a first annular adapter 172
surrounding the sidewalls 104 of the chamber 100. The resting
surface 314 may have a plurality of slots shaped to receive a pin
to align the lower shield 160 to the first annular adapter 172.
[0044] As shown in FIG. 3B, the top wall 312 comprises an inner
periphery 326 and an outer periphery 328. The outer periphery 328
extends to form a sloped step 330. The sloped step 330 is angled
radially outward between about 5 degrees and about 10 degrees from
vertical, for example, about 8 degrees from vertical. In one
embodiment, the inner periphery 326 is angled radially inward
between about 2 degrees and about 5 degrees, for example, about 3.5
degrees from vertical.
[0045] The first annular adapter 172 supports the lower shield 160
and can serve as a heat exchanger about the sidewall 104 of the
substrate processing chamber 100. The first annular adapter 172 and
shield 160 form an assembly that allows for better heat transfer
from the shield 160 to the adapter 172 and which reduces thermal
expansion stresses on the material deposited on the shield.
Portions of the shield 160 can become excessively heated by
exposure to the plasma formed in the substrate processing chamber,
resulting in thermal expansion of the shield and causing sputtering
deposits formed on the shield to flake off from the shield and fall
upon and contaminate the substrate 105. The first adapter 172 has a
contact surface 174 that contacts the resting surface 314 of the
lower shield 160 to allow good thermal conductivity between the
shield 160 and the adapter 172. In one embodiment, the resting
surface 314 of the shield 160 and the contact surface 174 of the
first adapter 172 each have a surface roughness of from about 10 to
about 80 microinches, or even from about 16 to about 63
microinches, or in one embodiment an average surface roughness of
about 32 microinches. In one embodiment, the first adapter 172
further comprises conduits for flowing a heat transfer fluid
therethrough to control the temperature of the first adapter
172.
[0046] Below the support ledge 313 of the lower shield 160 is a
bottom wall 316 that surrounds the substrate support 128. A base
plate 318 extends radially inward from the bottom wall 316 of the
cylindrical outer band 310. A cylindrical inner band 320 is coupled
with the base plate 318 and at least partially surrounding the
peripheral wall 138 of the substrate support 128. The cylindrical
inner band 320, the base plate 318, and the cylindrical outer band
310 form a U-shaped channel. The cylindrical inner band 320
comprises a height that is less than the height of the cylindrical
outer band 310. In one embodiment, the height of the inner band 320
is about one fifth of the height of the cylindrical outer band 310.
In one embodiment, the bottom wall 316 has a notch 322. In one
embodiment, the cylindrical outer band 310 has a series of gas
holes 324.
[0047] The cylindrical outer band 310, the top wall 312, the
support ledge 313, the bottom wall 316, and the inner cylindrical
band 320 comprise a unitary structure. For example, in one
embodiment, the entire lower shield 160 can be made from 300 series
stainless steel, or in another embodiment, aluminum. A unitary
lower shield 160 is advantageous over prior shields which included
multiple components, often two or three separate pieces to make up
the complete lower shield. For example, a single piece shield is
more thermally uniform than a multiple-component shield, in both
heating and cooling processes. For example, the single piece lower
shield 160 has only one thermal interface to the first adapter 172,
allowing for more control over the heat exchange between the shield
160 and the first adapter 172. A shield 160 with multiple
components makes it more difficult and laborious to remove the
shield for cleaning. The single piece shield 160 has a continuous
surface exposed to the sputtering deposits without interfaces or
corners that are more difficult to clean out. The single piece
shield 160 also more effectively shields the sidewalls 104 from
sputter deposition during process cycles.
[0048] In one embodiment, the exposed surfaces of the lower shield
160 are treated with CLEANCOAT.TM., which is commercially available
from Applied Materials, Santa Clara, Calif. CLEANCOAT.TM. is a
twin-wire aluminum arc spray coating that is applied to substrate
processing chamber components, such as the lower shield 160, to
reduce particle shedding of deposits on the lower shield 160 and
thus prevent contamination of a substrate 105 in the chamber 100.
In one embodiment, the twin-wire aluminum arc spray coating on the
lower shield 160 has a surface roughness of from about 600 to about
2300 microinches.
[0049] The lower shield 160 has exposed surfaces facing the
interior volume 110 in the chamber 100. In one embodiment, the
exposed surfaces are bead blasted to have a surface roughness of
175.+-.75 microinches. The texturized bead blasted surfaces serve
to reduce particle shedding and prevent contamination within the
chamber 100. The surface roughness average is the mean of the
absolute values of the displacements from the mean line of the
peaks and valleys of the roughness features along the exposed
surface. The roughness average, skewness, or other properties may
be determined by a profilometer that passes a needle over the
exposed surface and generates a trace of the fluctuations of the
height of the asperities on the surface, or by a scanning electron
microscope that uses an electron beam reflected from the surface to
generate an image of the surface.
[0050] With reference to FIGS. 4A-4C, the deposition ring 180
comprises an annular band 402 that extends about and surrounds the
peripheral wall 138 of the support 128 as shown in FIG. 2. The
annular band 402 comprises an inner lip 404 which extends
transversely from the band 402 and is substantially parallel to the
peripheral wall 138 of the support 128. The inner lip 404
terminates immediately below the overhanging edge 107 of the
substrate 105. The inner lip 404 defines an inner perimeter of the
deposition ring 180 which surrounds the periphery of the substrate
105 and substrate support 128 to protect regions of the support 128
that are not covered by the substrate 105 during processing. For
example, the inner lip 404 surrounds and at least partially covers
the peripheral wall 138 of the support 128 that would otherwise be
exposed to the processing environment, to reduce or even entirely
preclude deposition of sputtering deposits on the peripheral wall
138. Advantageously, the deposition ring 180 can be easily removed
to clean sputtering deposits from the exposed surfaces of the ring
180 so that the support 128 does not have to be dismantled to be
cleaned. The deposition ring 180 can also serve to protect the
exposed side surfaces of the support 128 to reduce their erosion by
the energized plasma species.
[0051] In the embodiment shown in FIG. 2, the annular band 402 of
the deposition ring 180 has a v-shaped protuberance 406 that
extends along the central portion of the band 402 with a first
radially inward recess 408a and a second radially inward recess
408b on either side of the v-shaped protuberance 406. In one
embodiment, the opposing surfaces of the v-shaped protuberance 406
form an angle ".alpha.". In one embodiment, the angle ".alpha." is
between about 25.degree. and about 30.degree.. In another
embodiment, the angle ".alpha." is between about 27.degree. and
about 28.degree.. The first radially inward recess 408a is located
in a horizontal plane slightly below the horizontal plane of the
second radially inward recess 408b. In one embodiment, the second
radially inward recess 408b has a width between about 0.8 inches
and about 0.9 inches. In another embodiment, the second radially
inward recess 408b has a width between about 0.83 inches and about
0.84 inches. In one embodiment, the first radially inward recess
408a and the second radially inward recess 408b are substantially
parallel to a bottom surface 420 of the deposition ring 180. The
second radially inward recess 408b is spaced apart from the cover
ring 170 to form an arc-shaped channel 410 therebetween which acts
as a labyrinth to reduce penetration of plasma species into the
arc-shaped channel 410, as shown in FIG. 2. An open inner channel
412 lies between the inner lip 404 and the v-shaped protuberance
406. The open inner channel 412 extends radially inward to
terminate at least partially below the overhanging edge 107 of the
substrate 105. The open inner channel 412 facilitates the removal
of sputtering deposits from these portions during cleaning of the
deposition ring 180. The deposition ring 180 also has a ledge 414
which extends outward and is located radially outward of the
V-shaped protuberance 406. The ledge 414 serves to support the
cover ring 170. The bottom surface 420 of the annular band 402 has
a notch 422 which extends from the inner lip 404 under the V-shaped
protuberance 406. In one embodiment, the notch has a width between
about 0.6 inches and about 0.75 inches. In another embodiment, the
notch has a width between about 0.65 inches and about 0.69 inches.
In one embodiment, the notch has a height between about 0.020
inches and 0.030 inches. In another embodiment, the notch has a
height between about 0.023 inches and about 0.026 inches.
[0052] In one embodiment, the second radially inward recess 408b
has an outer diameter shown by arrows "A". In one embodiment, the
diameter "A" of the second radially inward recess 408b may be
between about 13 inches and about 13.5 inches. In another
embodiment, the diameter "A" of the second radially inward recess
408b may be between about 13.1 inches and about 13.2 inches. In one
embodiment, the second radially inward recess 408b has an inner
diameter shown by arrows "E". In one embodiment, the diameter "E"
of the second radially inward recess 408b may be between about 12
inches and about 12.5 inches. In another embodiment, the diameter
"E" may be between about 12.2 inches and 12.3 inches.
[0053] In one embodiment, the annular band 402 has a diameter as
shown by arrows "D". In one embodiment, the diameter "D" of the
annular band 402 may be between about 11 inches and about 12
inches. In another embodiment, the diameter "D" of the annular band
402 may be between about 11.25 inches and about 11.75 inches. In
yet another embodiment, the diameter "D" of the annular band 402
may be between about 11.40 inches and about 11.60 inches. In one
embodiment, the annular band 402 has an outer diameter as shown by
arrows "F". In one embodiment, the diameter "F" of the annular band
402 may be between about 13 inches and about 14 inches. In another
embodiment, the diameter "F" of the annular band 402 may be between
about 13.25 inches and about 13.75 inches. In yet another
embodiment, the diameter "F" may be between 13.40 inches and about
13.60 inches.
[0054] In one embodiment the top of the v-shaped protuberance has a
diameter shown by arrows "B". In one embodiment, the diameter "B"
may be between about 12 inches and about 12.3 inches. In another
embodiment, the diameter "B" may be between about 12.1 inches and
about 12.2 inches.
[0055] In one embodiment, the inner lip 404 has an outer diameter
shown by arrows "C". In one embodiment, the diameter "C" may be
between about 11 inches and about 12 inches. In another embodiment,
the diameter "C" may be between about 11.5 inches and about 11.9
inches. In yet another embodiment, the diameter "C" may be between
about 11.7 inches and about 11.8 inches.
[0056] The deposition ring 180 can be made by shaping and machining
a ceramic material, such as aluminum oxide. Preferably, the
aluminum oxide has a purity of at least about 99.5 percent to
reduce contamination of the chamber 100 by undesirable elements
such as iron. The ceramic material is molded and sintered using
conventional techniques such as isostatic pressing, followed by
machining of the molded sintered preform using suitable machining
methods to achieve the shape and dimensions required.
[0057] The annular band 402 of the deposition ring 180 may comprise
an exposed surface that is grit blasted. Grit blasting is performed
with a grit size suitable to achieve the predefined surface
roughness. In one embodiment, a surface of the deposition ring 180
is treated with a twin-wire aluminum arc-spray coating, such as,
for example, CLEANCOAT.TM., to reduce particle shedding and
contamination.
[0058] FIG. 5A is a partial section view of a middle shield 190
according to one embodiment described herein. The middle shield 190
encircles the sputtering surface 134 of the sputtering target 136
that faces the substrate support 128. The middle shield 190 covers
and shadows the top wall 312 of the lower shield 160 and the
sidewalls 104 of the chamber 100 to reduce deposition of sputtering
deposits originating from the sputtering surface 134 of the
sputtering target 136 onto the components and surfaces behind the
middle shield 160.
[0059] As shown in FIG. 1 and FIG. 5A, the middle shield 160 is of
unitary construction and comprises a cylindrical band 510 having a
first diameter D1 dimensioned to encircle the upper shield 195. The
cylindrical outer band 310 has a top wall 512 that surrounds the
upper shield 195, a middle wall 517, and a bottom wall 518. A
mounting flange 514 extends radially outward from the top wall 512
of the cylindrical band 510. The mounting flange 514 comprises a
resting surface 516 to rest upon a second annular adapter 176
surrounding the sidewalls 104 of the chamber 100. The resting
surface may comprise a plurality of slots shaped to receive a pin
to align the middle shield 190 to the adapter 176.
[0060] The middle wall 517 is an extension of the top wall 512. The
middle wall 517 is sloped radially inward from the top wall 512
beginning at a transition point between the top wall 512 and the
middle wall 517. In one embodiment the middle wall 517 is angled
between about 5.degree. and about 10.degree. from vertical, for
example, about 7.degree. from vertical. The middle wall 517 of the
cylindrical band forms a second diameter D2. The second diameter D2
is dimensioned to fit within the sloped portion of the top wall 312
of the lower shield 160.
[0061] The bottom wall 518 is an extension of the middle wall 517.
The bottom wall 518 is sloped radially outward relative to the
middle wall 517 beginning at a transition point between the middle
wall 517 and the bottom wall 518. In one embodiment the bottom wall
518 is angled between about 1.degree. and about 5.degree. from
vertical, for example, about 4.degree. from vertical.
[0062] The top wall 512, the middle wall 517, the bottom wall 518,
and the mounting flange 514 comprise a unitary structure. For
example, in one embodiment, the entire middle shield 190 can be
made from 300 series stainless steel, or in another embodiment,
aluminum.
[0063] With reference to FIGS. 1, 2, 6A, 6B, and 6C, the cover ring
170 encircles and at least partially covers the deposition ring 180
to receive, and thus, shadow the deposition ring 180 from the bulk
of the sputtering deposits. The cover ring 170 is fabricated from a
material that can resist erosion by the sputtering plasma, for
example, a metallic material such as stainless steel, titanium or
aluminum, or a ceramic material, such as aluminum oxide. In one
embodiment, the cover ring 170 is composed of titanium having a
purity of at least about 99.9 percent. In one embodiment, a surface
of the cover ring 170 is treated with a twin-wire aluminum
arc-spray coating, such as, for example, CLEANCOAT.TM., to reduce
particle shedding from the surface of the cover ring 170. The cover
ring has an outer diameter shown by arrows "H". In one embodiment,
the diameter "H" is between about 14.5 inches and about 15 inches.
In another embodiment, the diameter "H" is between about 14.8
inches and about 14.9 inches. The cover ring has an inner diameter
shown by arrows "I". In one embodiment, the diameter "I" is between
about 11.5 inches and about 12.5 inches. In another embodiment, the
diameter "I" is between about 11.8 inches and about 12.2 inches. In
yet another embodiment, the diameter "I" is between about 11.9
inches and about 12.0 inches.
[0064] The cover ring 170 comprises an annular wedge 602. The
annular wedge comprises a top surface 603 and a bottom surface 604
to rest upon the ledge 414 of the deposition ring 180. The top
surface 603 is substantially parallel to the bottom surface 604. An
inclined top surface 603 couples the top surface 603 with a
projecting brim 610. The inclined top surface 605 is sloped
radially inwards and encircles the substrate support 128. The
inclined top surface 605 of the annular wedge 602 has an inner and
outer periphery 606, 608. The inner periphery 606 comprises the
projecting brim 610 which overlies the second radially inward
recess 408b of the deposition ring 180 forming an arc shaped
channel 410 of the deposition ring 180. The projecting brim 610
reduces deposition of sputtering deposits on the arc shaped channel
410 of the deposition ring 180. Advantageously, the projecting brim
610 projects a distance corresponding to at least about half the
width of the open inner channel 412 formed with the deposition ring
180. The projecting brim 610 is sized, shaped, and positioned to
cooperate with and complement the arc-shaped channel 410 and open
inner channel 412 to form a convoluted and constricted flow path
between the cover ring 170 and deposition ring 180 that inhibits
the flow of process deposits onto the peripheral wall 138. The
constricted flow path of the arc-shaped channel 410 restricts the
build-up of low-energy sputter deposits on the mating surfaces of
the deposition ring 180 and the cover ring 170, which would
otherwise cause them to stick to one another or to the peripheral
overhanging edge of the substrate 105. The open inner channel 412
of the deposition ring 180 which extends underneath the overhanging
edge 107 of the substrate 105 is designed in conjunction with
shadowing from the projecting brim 610 of the cover ring 170 to
collect, for example, aluminum sputter deposits in an aluminum
sputtering chamber, while reducing or even substantially precluding
sputter deposition on the mating surfaces of the two rings 170,
180.
[0065] The inclined top surface 605, in cooperation with the
projecting brim 610, block line-of-sight deposition from exiting
the interior volume 110 and entering the chamber body cavity. The
inclined top surface 605 may be slanted at an angle relative to the
top surface 603 as shown by angle ".beta.". In one embodiment, the
angle ".beta." may be between about 5 degrees and about 15 degrees.
In another embodiment, the angle ".beta." is between about 9
degrees and about 11 degrees. In one embodiment, the angle ".beta."
is about 10 degrees. The angle of the inclined top surface 605 of
the cover ring 170 is designed, for example, to minimize the
buildup of sputter deposits nearest to the overhanging edge 107 of
the substrate 105, which would otherwise negatively impact the
deposition uniformity obtained across the substrate 105.
[0066] The cover ring 170 further comprises a sloped step 612
located below the inclined top surface 605 of the annular wedge
602. The sloped step 612 couples the projecting brim 610 with the
bottom surface 604. The sloped step 612 extends downwardly from the
annular wedge 602 and radially outward from the inner periphery
606. The sloped step 612 may be slanted at an angle relative to the
bottom surface as shown by angle ".gamma.". In one embodiment,
angle ".gamma." may be between about 40 degrees and about 50
degrees. In another embodiment, angle ".gamma." may be between
about 42 degrees and about 48 degrees. In yet another embodiment,
angle ".gamma." may be between about 44 degrees and about 46
degrees.
[0067] The sloped step has an inner diameter shown by arrows "J".
In one embodiment, the diameter "J" of the sloped step 612 is
between about 12 inches and about 13 inches. In another embodiment,
the diameter "J" of the sloped step 612 is between about 12.2 and
about 12.5 inches. In yet another embodiment, the diameter "J" of
the sloped step 612 is between about 12.3 inches and about 12.4
inches. The sloped step 612 also has a diameter shown by arrows
"K". In one embodiment, the diameter "K" of the sloped step 612 is
between about 12.5 and about 13 inches. In another embodiment, the
diameter "K" of the sloped step 612 is between about 12.7 inches
and about 12.8 inches. In one embodiment, the diameter "K" of the
sloped step 612 functions as the inner diameter of the bottom
surface 604.
[0068] The bottom surface has an outer diameter shown by arrows
"L". In one embodiment, the diameter "L" of the bottom surface is
between about 13.5 and about 13.8 inches. In another embodiment,
the diameter "L" is between about 13.4 inches and about 13.5
inches.
[0069] The cover ring 170 further comprises an inner cylindrical
band 614a and an outer cylindrical band 614b that extend downwardly
from the annular wedge 602, with a gap 616 therebetween. In one
embodiment, the gap 616 has a width between 0.5 inches and about 1
inch. In another embodiment, the gap 616 has a width between about
0.7 inches and about 0.8 inches. In one embodiment, the inner and
outer cylindrical bands 614a, 614b are substantially vertical. The
cylindrical bands 614a, 614b are located radially outward of the
sloped step 612 of the wedge 602. An inner periphery 618 of the
inner cylindrical band 614a is coupled with the bottom surface 604.
In one embodiment, the inner periphery 618 of the inner cylindrical
band 614a may be slanted at an angle ".phi." from vertical. In one
embodiment, the angle ".phi." is between about 10 degrees and about
20 degrees. In another embodiment, the angle ".phi." is between
about 14 degrees and about 16 degrees.
[0070] The inner cylindrical band 614a has a height that is smaller
than the outer cylindrical band 614b. Typically, the height of the
outer cylindrical band 614b is at least about 2 times the height of
the inner cylindrical band 614a. In one embodiment, the height of
the outer cylindrical band 614b is between about 0.4 inches and
about 1 inch. In another embodiment, the height of the outer
cylindrical band 614b is between 0.6 inches and 0.7 inches. In one
embodiment, the height of the inner cylindrical band 614a is
between about 0.2 inches and 0.6 inches. In another embodiment, the
height of the inner cylindrical band 614a is between about 0.3
inches and 0.4 inches.
[0071] In one embodiment, the outer diameter "L" of the bottom
surface functions as the inner diameter of the inner cylindrical
band 614a. The inner cylindrical band 614a has an outer diameter
shown by arrows "M". In one embodiment, the diameter "M" of the
inner cylindrical band 614a is between about 13.5 inches and about
14.2 inches. In another embodiment, the diameter "M" of the inner
cylindrical band 614a is between about 13.7 and 14 inches. In yet
another embodiment, the diameter "M" of the inner cylindrical band
is between about 13.8 inches and about 13.9 inches.
[0072] In one embodiment, the outer cylindrical band 614b has an
inner diameter as shown by arrows "N". In one embodiment, the
diameter "N" is between about 14 inches and about 15 inches. In
another embodiment, the diameter "N" of the outer cylindrical band
614b is between about 14.2 inches and about 14.8 inches. In another
embodiment, the diameter "N" of the outer cylindrical band 614b is
between about 14.5 inches and about 14.6 inches. In one embodiment,
the diameter "H" of the cover ring functions as the outer diameter
of the outer cylindrical band "H".
[0073] In one embodiment, the cover ring 170 is adjustable and
effectively shields conductance holes in the lower shield 160 at a
range of different heights. For example, the cover ring 170 is
capable of being raised and lowered to adjust the height of the
cover ring 170 in relationship to the substrate support 128 in the
chamber 100.
[0074] The space or gap between the lower shield 160 and cover ring
170 forms a convoluted S-shaped pathway or labyrinth for plasma to
travel. The shape of the pathway is advantageous, for example,
because it hinders and impedes ingress of plasma species into this
region, reducing undesirable deposition of sputtered material.
[0075] 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.
* * * * *