U.S. patent application number 11/535658 was filed with the patent office on 2007-04-12 for heat transfer assembly.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Alexander Matyushkin, Boris S. Yendler.
Application Number | 20070079761 11/535658 |
Document ID | / |
Family ID | 33417989 |
Filed Date | 2007-04-12 |
United States Patent
Application |
20070079761 |
Kind Code |
A1 |
Yendler; Boris S. ; et
al. |
April 12, 2007 |
HEAT TRANSFER ASSEMBLY
Abstract
A heat transfer assembly having a heat spreading member
sandwiched between a heat source and a heat sink is disclosed. The
heat sink, the heat spreading member, and the heat source are
pressed against the bottom of a substrate support plate by a bias
member.
Inventors: |
Yendler; Boris S.;
(Saratoga, CA) ; Matyushkin; Alexander; (San Jose,
CA) |
Correspondence
Address: |
MOSER IP LAW GROUP / APPLIED MATERIALS, INC.
1040 BROAD STREET
2ND FLOOR
SHREWSBURY
NJ
07702
US
|
Assignee: |
Applied Materials, Inc.
Santa Clara
CA
|
Family ID: |
33417989 |
Appl. No.: |
11/535658 |
Filed: |
September 27, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10440365 |
May 16, 2003 |
|
|
|
11535658 |
Sep 27, 2006 |
|
|
|
Current U.S.
Class: |
118/728 |
Current CPC
Class: |
C23C 16/4586 20130101;
C23C 16/52 20130101; Y02P 80/30 20151101 |
Class at
Publication: |
118/728 |
International
Class: |
C23C 16/00 20060101
C23C016/00 |
Claims
1. A heat transfer assembly for a substrate support in a substrate
processing system, comprising: a first contact plate; a second
contact plate disposed below the first contact plate; and a heat
spreading member sandwiched between the first and the second
contact plates, wherein the heat transfer assembly is configured to
be disposed between a heat source and a heat sink in a substrate
support and to reduce temperature non-uniformity caused by features
formed in the substrate support, and wherein the first and second
contact plates reduce heat flux through the heat transfer
assembly.
2. The heat transfer assembly of claim 1, wherein the heat
spreading member has a higher thermal conductivity than the first
and second contact plates.
3. The heat transfer assembly of claim 1, wherein the heat
spreading member is between about 3-12 millimeters thick.
4. The heat transfer assembly of claim 1, wherein the first and the
second contact plates are between about 3-12 millimeters thick.
5. The heat transfer assembly of claim 1, wherein the first and
second contact plates each comprise one smooth contact surface and
one embossed contact surface.
6. The heat transfer assembly of claim 5, wherein the embossed
contact surface comprises an area that is about 5 to 50% of the
surface area of the smooth contact surface.
7. The heat transfer assembly of claim 5, wherein embossment in a
first region of the embossed contact surface differs from
embossment in at least one other region of the embossed contact
surface.
8. The heat transfer assembly of claim 5, wherein the embossed
contact surface of the first contact plate contacts an upper
surface of the heat spreader member and a the smooth contact
surface of the second contact plate contacts a bottom surface of
the heat spreader member.
9. The heat transfer assembly of claim 1, wherein the heat
spreading member is formed of a material selected from the group
consisting of aluminum nitride (AlN) and copper (Cu).
10. The heat transfer assembly of claim 1, wherein the first and
second contact plates are formed of a material selected from the
group consisting of titanium (Ti) and an alloy comprising iron
(Fe), nickel (Ni) and cobalt (Co).
11. The heat transfer assembly of claim 1, wherein a thermally
conductive sheet is disposed in least one of the following
locations: adjacent a top surface of the first contact plate,
immediately between the first contact plate and the heat spreader
member, immediately between the heat spreader member and the second
contact plate, or adjacent a lower surface of the second contact
plate.
12. The heat transfer assembly of claim 11, wherein the thermally
conductive sheet is formed of a material selected from the group
consisting of graphite and aluminum.
13. The heat transfer assembly of claim 11, wherein the thermally
conductive sheet is between about 1-5 micrometers thick.
14. Apparatus for processing a semiconductor substrate, comprising:
a process chamber; and a substrate support disposed in the process
chamber comprising a heat spreading member sandwiched between a
first contact plate and a second contact plate, wherein the first
contact plate is thermally coupled to a heat source and the second
contact plate is thermally coupled to a heat sink, wherein the heat
spreading member is configured to reduce temperature non-uniformity
caused by features formed in the substrate support, and wherein the
first and second contact plates reduce heat flux from the heat
source to the heat sink.
15. The apparatus of claim 14, wherein the heat source is an
embedded heater.
16. The apparatus of claim 15, wherein the embedded heater is a
detachable heater that is thermally coupled to a substrate support
plate of the substrate support.
17. The apparatus of claim 14, wherein the first and second contact
plates each comprise one smooth contact surface and one embossed
contact surface, wherein the embossed contact surface of the first
contact plate contacts an upper surface of the heat spreader member
and a the smooth contact surface of the second contact plate
contacts a bottom surface of the heat spreader member.
18. The apparatus of claim 17, wherein embossment in a first region
of the embossed contact surface differs from embossment in at least
one other region of the embossed contact surface.
19. The apparatus of claim 14, wherein the heat spreading member is
formed of a material selected from the group consisting of aluminum
nitride (AlN) and copper (Cu).
20. The apparatus of claim 14, wherein the first and second contact
plates are formed of a material selected from the group consisting
of titanium (Ti) and an alloy comprising iron (Fe), nickel (Ni) and
cobalt (Co).
21. The apparatus of claim 14, further comprising at least one bias
member that engages and improves thermal coupling between a
substrate support plate, the heat source, the heat transfer
assembly, and the heat sink.
22. The apparatus of claim 21, wherein each bias member exerts an
expanding elastic force and is disposed in the heat sink or a base
member coupled to the heat sink.
23. The apparatus of claim 14, wherein a thermally conductive sheet
is disposed immediately between at least one of the following: a
bottom surface of a substrate support plate and the heat source, a
bottom surface of the heat source and a top surface of the first
contact plate, a bottom surface of the first contact plate and a
top surface of the heat spreader member, a bottom surface of the
heat spreader member and a top surface of the second contact plate,
or a bottom surface of the second contact plate and a top surface
of a heat sink.
24. The apparatus of claim 23, wherein the thermally conductive
sheet is formed of a material selected from the group consisting of
graphite and aluminum and is between about 1-5 micrometers
thick.
25. A substrate support, comprising: a heat source disposed beneath
a support surface of the substrate support; a heat sink disposed
beneath the heat source; and a heat transfer assembly thermally
coupling the heat source to the heat sink, the heat transfer
assembly comprising: a heat spreading member sandwiched between a
first contact plate and a second contact plate, wherein the first
and second contact plates reduce heat flux through the heat
transfer assembly.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S. patent
application Ser. No. 10/440,365, filed May 16, 2003, which is
herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to semiconductor
substrate processing systems. More specifically, the invention
relates to an apparatus for supporting a substrate in a
semiconductor substrate processing system.
[0004] 2. Description of the Related Art
[0005] Accurate reproducibility of substrate processing is an
important factor when increasing productivity for integrated
circuit fabrication processes. Precise control of various process
parameters is required for achieving consistent results across a
substrate, as well as results that are reproducible from substrate
to substrate. More particularly, uniformity of the substrate
temperature during processing is one requirement for achieving
accurate reproducibility. During substrate processing, changes in
the temperature and temperature gradients across the substrate are
detrimental to material deposition, etch rate, step coverage,
feature taper angles, and the like.
[0006] Generally, during processing, the substrate is disposed on a
substrate support (e.g., electrostatic chuck, susceptor, and the
like) that is thermally coupled to a heat source, such as an
embedded heater, e.g., a resistive heater and the like.
Additionally, in some applications, heat is also produced by the
process itself (e.g., plasma process). To enhance the processing
and minimize undesirable yield losses, it is essential to control
the temperature as well as the temperature uniformity of the
substrate.
[0007] Therefore, there is a need in the art for a substrate
support having means to control the temperature as well as the
temperature uniformity of the substrate.
SUMMARY OF THE INVENTION
[0008] The disadvantages associated with the prior art are overcome
by an improved substrate support for a semiconductor substrate
processing system. The substrate support comprises a heat transfer
assembly having a heat spreader member that is sandwiched between a
heat source and a heat sink. The heat sink, heat spreader member,
and heat source are pressed against the bottom of a substrate
support plate by a bias member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The teachings of the present invention can be readily
understood by considering the following detailed description in
conjunction with the accompanying drawings, in which:
[0010] FIG. 1 depicts a schematic diagram of an exemplary
processing reactor comprising a substrate support in accordance
with one embodiment of the present invention;
[0011] FIG. 2 is a schematic, cross-sectional view of a heat
transfer assembly of the substrate support of FIG. 1 in accordance
with one embodiment of the present invention; and
[0012] FIG. 3 is a schematic, top plan view of the heat transfer
assembly of FIG. 2.
[0013] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures.
[0014] It is to be noted, however, that the appended drawings
illustrate only exemplary 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.
DETAILED DESCRIPTION
[0015] The present invention is a heat transfer assembly for
controlling the temperature and temperature uniformity of a
substrate support in a substrate processing system. The substrate
support is generally used to support a substrate (e.g., silicon
(Si) wafer) in a process chamber of the substrate processing
system, such as a plasma etching reactor, a reactive ion etching
(RIE) reactor, a chemical vapor deposition (CVD) reactor, a plasma
enhanced CVD (PECVD) reactor, a physical vapor deposition (PVD)
reactor, an electron cyclotron resonance (ECR) reactor, a rapid
thermal processing (RTP) reactor, an ion implantation system, and
the like. The invention is useful in applications that require a
substrate to be supported in a chamber while the temperature of the
substrate is required to be substantially uniform.
[0016] FIG. 1 depicts a schematic diagram of an exemplary Decoupled
Plasma Source (DPS II) etch reactor 100 that may be used to
practice the invention. The DPS II reactor is commercially
available from Applied Materials, Inc. of Santa Clara, Calif. The
particular embodiment of the reactor 100 shown herein is provided
for illustrative purposes and should not be used to limit the scope
of the invention. For example, the invention can be used in
apparatus other than a system for processing substrates, whether
fabricated of semiconductor materials or other materials.
[0017] The reactor 100 comprises a process chamber 110 and a
controller 140.
[0018] The process chamber 110 generally comprises a conductive
body (wall) 130 having a substantially flat dielectric ceiling 120
and encompassing a substrate support 116. The process chamber 110
may have other types of ceilings, e.g., a dome-shaped ceiling. The
wall 130 typically is coupled to an electrical ground terminal
134.
[0019] Above the ceiling 120 is disposed an antenna comprising at
least one inductive coil element 112 (two co-axial elements 112 are
shown). The inductive coil element 112 is coupled, through a first
matching network 119, to a plasma power source 118. The plasma
power source 118 generally is capable of producing up to 5000 W at
a tunable frequency in a range from about 50 kHz to 13.6 MHz. The
matching network 119 and the plasma power source 118 are controlled
by the controller 140.
[0020] The support pedestal 116 is coupled, through a second
matching network 124, to a biasing power source 122. The biasing
power source 122 generally is a source of up to 2000 W of
continuous or pulsed power at a frequency of approximately 13.6
MHz. In other embodiments, the biasing power source 122 may be a DC
or pulsed DC power source. The biasing power source 122 and the
matching network 124 are controlled by the controller 140.
[0021] During processing, a substrate 114 is placed on the support
pedestal 116 and thereafter process gases are supplied from a gas
panel 138 through at least one entry port 126 to form a gaseous
mixture 150 in the process chamber 110. Operation of the gas panel
138 is controlled by the controller 140. The gaseous mixture 150 is
ignited to a plasma 155 in the process chamber 110 by applying
power from the plasma source 118 to the at least one inductive coil
element 112, while the substrate 114 may be also biased by applying
power from the biasing source 122 to the substrate support 116.
[0022] The lift mechanism 162, as controlled by the controller 140,
is used to raise the substrate 114 off the substrate support 116 or
to lower the substrate onto the substrate support. Generally, the
lift mechanism 162 comprises an actuator that engages a lift plate
(both are not shown) coupled to a plurality of lift pins 172 (one
lift pin is illustratively shown in FIG. 1). The lift pins 172
travel through respective guide holes 188. Illustratively, the
guide holes 188 are defined by an inner passage of tubes 206 that
are supported by bushings 208 (discussed in reference to FIG.
2).
[0023] In one embodiment, the guide holes 188 are equidistantly
distributed along a circle 310 (shown in phantom in FIG. 3) that is
concentric with the substrate support 116. Such lift mechanism is
disclosed in commonly assigned U.S. patent application Ser. No.
10/241,005, filed Sep. 10, 2002 (Attorney docket number 7262),
which is incorporated herein by reference.
[0024] Gas pressure within the interior of the chamber 110 is
controlled by the controller 140 using a throttle valve 127 and a
vacuum pump 136. The temperature of the wall 130 may further be
controlled using liquid-containing conduits (not shown) running
through the wall. The process chamber 110 also comprises
conventional systems for process control, including, for example,
internal process diagnostics, and the like. Such systems are
collectively depicted in FIG. 1 as support systems 107.
[0025] To facilitate control of the components and substrate
processing within the chamber 110, the controller 140 may be one of
any form of general-purpose computer processor that can be used in
an industrial setting for controlling various chambers and
sub-processors. The controller 140 generally comprises a central
processing unit (CPU) 144, a memory 142, and support circuits 146
for the CPU 144.
[0026] Those skilled in the art will understand that other forms of
process chambers may be used to practice the invention, such as
electron cyclotron resonance (ECR) chambers, chemical vapor
deposition (CVD) chambers, plasma enhanced CVD (PECVD) chambers,
physical vapor deposition (PVD) chambers, rapid thermal processing
(RTP) chambers, and any other chamber that may incorporate a
substrate support having an embedded heater therein.
[0027] In one depicted embodiment, the support pedestal 116
comprises a substrate support plate 160, a heat source (such as an
embedded heater) 132, a heat transfer assembly 164, a heat sink
(such as a cooling plate) 166, at least one bias member 190, and a
mounting assembly 106. In alternative embodiments, the substrate
support plate 160 may comprise an electrostatic chuck (as shown) or
another substrate retention mechanism, e.g., a mechanical chuck, a
susceptor clamp ring, vacuum chuck, and the like.
[0028] In operation, the substrate 114 generally should be heated
to a pre-selected temperature (e.g., from about 0 to 500 degrees
Celsius). The substrate 114 is heated with minimal non-uniformity
across the substrate and then maintained at such temperature. The
temperature of the substrate 114 is controlled by stabilizing the
temperature of the support pedestal 116 using an embedded heater
132 and a heat transfer gas (e.g., helium (He)). The embedded
heater 132 is used to heat the support pedestal 116 while the heat
transfer gas cools down the substrate 114. Generally, helium is
provided to the underside of the substrate 114 from a source 148
through a gas conduit 149 to channels and grooves (not shown)
formed in a top surface 174 of the substrate support plate 160.
[0029] In one embodiment of the substrate support plate 160, an
electrostatic chuck comprises at least one clamping electrode 180
that may be conventionally controlled by a chuck power supply 176.
The embedded heater 132 (e.g., resistive electric heater) comprises
at least one heating element 182 and is regulated by a heater power
supply 178.
[0030] In one embodiment, the embedded heater 132 is a detachable
heater that is thermally coupled to a bottom surface 133 of the
substrate support plate 160. The at least one bias member 190
applies force to the heater 132 to press it against the bottom
surface 133 of the substrate support plate 160. In an alternative
embodiment, the heater 132 may be embedded in the substrate support
plate (e.g., electrostatic chuck) 160 or be bonded to the bottom
surface 133 of the substrate support plate 160.
[0031] The substrate support plate 160 and embedded heater 132 are
generally formed from dielectric materials having a high thermal
conductivity (e.g., aluminum nitride (AlN) and the like), as well
as low coefficients of thermal expansion. The coefficients of
thermal expansion for each of the substrate support plate 160 and
the heater 132 should be matched. The high thermal conductivity
increases thermal coupling between the substrate support plate 160
and the heater 132 to facilitate uniform temperatures for the
support surface 174 of the plate 160 and a substrate 114 thereon.
The matching low coefficients of thermal expansion reduce the
expansion/contraction of the substrate support plate 160 relative
to the heater 132 across a broad range of temperatures (e.g., from
about 0 to 500 degrees Celsius).
[0032] The heat transfer assembly 164 facilitates a controlled heat
sink path to the cooling plate 166, for heat generated by the
embedded heater 132, as well as for heat produced during substrate
processing, e.g., plasma processing. By regulating the total and
local thermal conductivity of the heat transfer assembly 164,
temperature uniformity for the substrate support 116 may be
achieved.
[0033] The heat transfer assembly 164 is used to selectively
optimize over a broad range of temperatures and process parameters
the thermal properties (i.e., temperature uniformity and maximum
temperature) of the substrate support 116. In one embodiment, the
heat transfer assembly 164 comprises an electrostatic chuck and
embedded heater. The electrostatic chuck and embedded heater may
each be of a variety of design configurations. Specifically, the
heat transfer assembly 164 may be used to selectively optimize the
thermal properties of a substrate support 116 having a detachable
embedded heater, e.g., resistive electric heater.
[0034] The cooling plate 166 is thermally coupled to the heat
transfer assembly 164 and generally, is formed from a metal, such
as aluminum (Al), copper (Cu), stainless steel, and the like.
[0035] In the depicted embodiment, the cooling plate 166 comprises
a plurality of recesses 192, e.g., blind holes, grooves, and the
like. Each recess 192 houses a bias member 190, including at least
one cylindrical spring and the like. The bias member 190 exerts an
expanding elastic force. Such force engages the substrate support
plate 160, embedded heater 162, heat transfer assembly 164, and
cooling plate 166 against one another and facilitates thermal
coupling between the components of the substrate support 116.
[0036] The bias members 190 are disposed such that the substrate
support plate 160, embedded heater 162, heat transfer assembly 164,
and cooling plate 166 are uniformly compressed against one another
to provide thermal coupling between the components. In one
exemplary embodiment, the bias members 190 are disposed along at
least one circle that is concentric with the substrate support 116,
e.g., around the lift pins 172. Alternatively, the bias members 190
may be similarly disposed in recesses that are formed in a surface
169 of the base plate 168, or both in the cooling plate 166 and
base plate 168.
[0037] The mounting assembly 106 generally comprises a base plate
(or ring) 168, a collar ring 184, a flange 162, and a plurality of
fasteners (e.g., screws, bolts, clamps, and the like) 167. The
fasteners 167 couple the flange 162, cooling plate 166 and base
plate 168 together to provide mechanical integrity for the
substrate support 116. In further embodiments (not shown), the
support pedestal 116 may also include various process-specific
improvements, e.g., a purge gas ring, lift bellows, substrate
shields, and the like.
[0038] In one embodiment, the collar ring 184 is formed from KOVAR
(i.e., an alloy comprising, by weight, about 54% iron (Fe), 29%
nickel (Ni), and 17% cobalt (Co)). Further, the collar ring 184 is
brazed to the substrate support plate 160 and flange 162 to
facilitate gas-tight coupling between the support plate and flange.
KOVAR has a low coefficient of thermal expansion and a low thermal
conductivity and is known in the art for forming strong brazed
bonds with materials, such as ceramics (support plate 160) and
metals (flange 162). KOVAR is commercially available from EFI of
Los Alamitos, Calif., and other suppliers.
[0039] The mounting assembly 106 encompasses an interior region 186
of the substrate support 116. In operation, the interior region 186
generally is maintained at a gas pressure that is higher than the
gas pressure in a reaction volume 141. Such higher gas pressure
(e.g., atmospheric pressure) prevents radio-frequency arcing within
the support pedestal 116 that otherwise is promoted by the biasing
power source 122.
[0040] FIG. 2 and FIG. 3 are, respectively, schematic,
cross-sectional and top plan views of a heat transfer assembly 164
of a substrate support 116 of the reactor 100. The cross-sectional
view in FIG. 2 is taken along a centerline 3-3 in FIG. 3.
[0041] Referring to FIGS. 2 and 3, in one illustrative embodiment,
the heat transfer assembly 164 comprises a heat spreader plate 254
that is sandwiched between a first contact plate 256 and a second
contact plate 258. Alternatively, the heat transfer assembly 164
may comprise a single composite sandwich-like member. Additionally,
the embedded heater 132 may be included in the heat transfer
assembly 164.
[0042] The first and second contact plates 256, 258 are used to
reduce, in a controlled manner, heat flux from the embedded heater
132 through the heat transfer assembly 164 to the cooling plate
166. The cooling plate 166 comprises conduits 210 that facilitate
coolant flow to remove heat from the cooling plate 166. The contact
plates 256, 258 may be formed from materials having a low thermal
conductivity, e.g., KOVAR, titanium (Ti), and the like. Generally,
the contact plates 256, 258 have a thickness of about 3 to 12
mm.
[0043] The first contact plate 256 has a flat (i.e., smooth) first
contact surface 256A and an embossed second contact surface 256B.
Similarly, the second contact plate 258 has a smooth first contact
surface 258A and an embossed second contact surface 258B. The
smooth first contact surfaces 256A, 258A engage a bottom surface
202 of the embedded heater 132 and a bottom surface 204 of the heat
spreader plate 254, respectively. Accordingly, the embossed second
contact surface 256B engages a top surface 203 of the heat spreader
plate 254, while the embossed second contact surface 256B engages a
top surface 205 of the cooling plate 166.
[0044] A surface area of the embossed second contact surfaces 256B,
258B generally comprises about 5 to 50% of the surface area of the
smooth first contact surfaces 256A, 258A, respectively. The second
contact surfaces 256B, 258B may be embossed using conventional
machining techniques, such as milling, turning, and the like.
[0045] Contact plates with a smaller embossed surface area provide
a corresponding lower thermal conductivity in the direction that is
orthogonal to the smooth contact surfaces. This means that contact
plates 256, 258 having a smaller embossed surface area will reduce
the heat flux from the embedded heater 132 at a slower rate then
contact plates having a larger embossed surface area. In one
exemplary embodiment, the surface area of the embossed contact
surfaces 256B, 258B comprise about 20% of the surface area of the
respective first contact surfaces 256A, 258A.
[0046] Further, a local pattern density for the embossed surfaces
256B, 258B (i.e., surface area in a specific region of contact
surface 256B or 258B) may be selected such that a contact plate has
a pre-determined local thermal conductivity. The pre-determined
local thermal conductivity in one region of a contact plate may be
higher or lower than the thermal conductivity in other regions of
the plate. Such contact plates may be used to control the flux of
heat in specific regions of the heat transfer assembly 164 to
improve temperature uniformity across the substrate support plate
160 as well as the substrate 114.
[0047] The heat spreader plate 254 reduces temperature
non-uniformity caused by features formed in the substrate support
116 (e.g., guide holes 188, gas conduit 149, the embossed surfaces
256B, 258B of the contact plates 256, 258, and the like).
Generally, the heat spreader plate 254 is formed to a thickness of
about 3 to 12 mm of a material having a high thermal conductivity
(e.g., aluminum nitride (AlN), copper (Cu), and the like).
[0048] The thermal conductivity of the heat transfer assembly 164
may be selectively controlled by choosing the materials and
thickness for the heat spreader plate 254 and contact plates 256,
258, as well as a pattern and pattern density of the embossed
contact surfaces 256B, 258B.
[0049] In one illustrative embodiment shown in FIG. 2, the embossed
contact surfaces 256B, 258B comprise a plurality of grooves 231
that are concentric with the substrate support 116. Each groove has
a width 261 and depth 259 of about 4 and 3 mm, respectively, and
the grooves are separated from one another by a wall having a
thickness 257 of about 3 mm.
[0050] In alternative embodiments, the embossed contact surfaces
256B, 258B each may comprise a plurality of parallel grooves,
orthogonal grooves, grooves separated by walls having different
thicknesses, and the like. To reduce temperature non-uniformity
across the substrate, the embossments generally have a higher
pattern density in areas that oppose hotter zones of the substrate
support plate 160, the embedded heater 132, or the substrate
114.
[0051] Thermally conductive sheets 213 may be placed between one or
more surfaces of the components comprising the substrate support
116. In one embodiment, the thermally conductive sheets 213 are
placed between the bottom surface 133 of the substrate support
plate 160 and the embedded heater 132 (shown in FIG. 2), the bottom
surface 202 of the embedded heater 132 and the top surface 256A of
the first contact plate 256 (not shown), the embossed surface 256B
of the first contact plate 256 and the top surface 203 of the heat
spreader plate 254 (not shown), the bottom surface 204 of the heat
spreader plate 254 and the top surface 258A of the second contact
plate 258 (not shown), and the embossed surface 258B of the second
contact plate and the top surface 205 of the cooling plate 166 (not
shown). Each thermally conductive sheet 213 has cutouts that
conform to the surfaces of the components they separate to allow
passage of lift pins 172 as well as the gas conduit 149. The
thermally conductive sheets 213 facilitate uniform heat transfer
between the components comprising the substrate support 116, when
such components are compressed by bias members 190.
[0052] The thermally conductive sheets 213 may comprise graphite
(GRAFOIL.RTM. flexible graphite commercially available from UCAR
International, Inc., Nashville, Tenn.), aluminum, and the like. The
thickness of the thermally conductive sheets 213 should be within a
range of about 1-5 micrometers.
[0053] The heat transfer assembly 164 described herein may also be
used to improve the temperature uniformity of a substrate placed on
a substrate support plate (e.g., electrostatic chuck) having a
detachable heater or, alternatively, a substrate support plate
having an embedded heater.
[0054] To facilitate isolation of the interior region 186, the base
plate 168 is supplied with gas-tight seals 281, 283, and 285.
Together, the seals and collar ring 184 isolate the interior region
186 from the reaction volume 141 (seal 281), guide hole 188 (seal
283), and gas conduit 149 (seal 285). In the illustrative
embodiment shown in FIG. 2, each such seal comprises an elastic
member (e.g., O-rings and the like) that is disposed in a
conventional manner in a circular groove.
[0055] Those skilled in the art will readily realize other
permissible modifications of the substrate support 116 and heat
transfer assembly 164 that facilitate advantageous in-situ control
of the substrate temperature and temperature non-uniformity.
[0056] While foregoing is directed to the illustrative embodiment
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.
* * * * *