U.S. patent application number 11/563272 was filed with the patent office on 2007-05-10 for method and apparatus for controlling temperature of a substrate.
Invention is credited to John Holland, Theodoros Panagopoulos.
Application Number | 20070102118 11/563272 |
Document ID | / |
Family ID | 36144104 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070102118 |
Kind Code |
A1 |
Holland; John ; et
al. |
May 10, 2007 |
METHOD AND APPARATUS FOR CONTROLLING TEMPERATURE OF A SUBSTRATE
Abstract
A pedestal assembly and method for controlling temperature of a
substrate during processing is provided. In one embodiment, the
pedestal assembly includes a support member that is coupled to a
base by a material layer. The material layer has at least two
regions having different coefficients of thermal conductivity. In
another embodiment, the support member is an electrostatic chuck.
In further embodiments, a pedestal assembly has channels formed
between the base and support member for providing cooling gas in
proximity to the material layer to further control heat transfer
between the support member and the base, thereby controlling the
temperature profile of a substrate disposed on the support
member.
Inventors: |
Holland; John; (San Jose,
CA) ; Panagopoulos; Theodoros; (Cupertino,
CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP;APPLIED MATERIALS INC
595 SHREWSBURY AVE
SUITE 100
SHREWSBURY
NJ
07702
US
|
Family ID: |
36144104 |
Appl. No.: |
11/563272 |
Filed: |
November 27, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10960874 |
Oct 7, 2004 |
|
|
|
11563272 |
Nov 27, 2006 |
|
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|
Current U.S.
Class: |
156/345.27 ;
118/724; 118/725; 118/728; 156/345.52; 156/345.53; 156/914 |
Current CPC
Class: |
H01L 21/67103 20130101;
H01L 21/6831 20130101; Y10T 279/23 20150115; H01L 21/67248
20130101 |
Class at
Publication: |
156/345.27 ;
118/725; 118/728; 156/345.52; 156/345.53; 156/914; 118/724 |
International
Class: |
C23F 1/00 20060101
C23F001/00; C23C 16/00 20060101 C23C016/00 |
Claims
1. A substrate pedestal assembly comprising: a substrate support
member; a base having a first surface; and a material layer
disposed between and contacting the first surface and the support
member, wherein the material layer comprises a plurality of
material regions, at least two of the material regions having
different coefficients of thermal conductivity.
2. The substrate pedestal assembly of claim 1, wherein at least one
region of the plurality of material regions has an anisotropic
coefficient of thermal conductivity.
3. The substrate pedestal assembly of claim 1, wherein at least one
region of the plurality of material regions is separated by a gap
from an adjacent material region.
4. The substrate pedestal assembly of claim 1, wherein the material
layer couples the support member to the first surface of the
base.
5. The substrate pedestal assembly of claim 4, wherein at least one
region of the material layer is thermally conductive adhesive
material.
6. The substrate pedestal assembly of claim 4, wherein at least one
region of the material layer comprises at least one thermally
conductive adhesive tape.
7. The substrate pedestal assembly of claim 4, wherein the material
layer is at least one of an acrylic based compound and silicon
based compound.
8. The substrate support pedestal assembly of claim 1, wherein the
material layer further comprises a ceramic filler selected from the
group consisting of aluminum oxide (Al.sub.2O.sub.3), aluminum
nitride (AlN), titanium diboride (TiB.sub.2), and combinations
thereof.
9. The substrate pedestal assembly of claim 1, wherein the regions
of the material layer have coefficients of thermal conductivity in
a range from 0.01 to 200 W/mK.
10. The substrate pedestal assembly of claim 1 further comprising
at least one channel adapted to provide a heat transfer medium
between the base and support member.
11. The substrate pedestal assembly of claim 10, wherein the at
least one channel is at least partially formed in the base.
12. The substrate pedestal assembly of claim 10, wherein the at
least one is at least partially formed in the support member.
13. The substrate pedestal assembly of claim 10, wherein the
pressure of the heat transfer medium in the at least one channel
may be selectively controlled in a range from about 760 to about 10
Torr.
14. The substrate pedestal assembly of claim 10, wherein the heat
transfer medium is He.
15. The substrate pedestal assembly of claim 10, wherein the at
least one channel is formed in the material layer.
16. The substrate pedestal assembly of claim 1, wherein the base
comprises at least one conduit fluidly coupled to a heat transfer
liquid source.
17. The substrate pedestal assembly of claim 10, wherein the
channel is formed between material regions having different
coefficients of thermal expansion.
18. The substrate pedestal assembly of claim 1, wherein the base
comprises at least one embedded heater electrically coupled to a
controlled power supply.
19. The substrate pedestal assembly of claim 1. wherein the base
comprises at least one embedded insert formed from a material
having a different coefficient of thermal conductivity than a
material of an adjacent region of the base.
20. The substrate pedestal assembly of claim 19, wherein the
material of the at least one embedded insert has a lower
coefficient of thermal conductivity than the material of the
adjacent region of the base.
21. The substrate pedestal assembly of claim 19, wherein the
material of the at least one embedded insert has an anisotropic
coefficient of thermal conductivity.
22. The substrate pedestal assembly of claim 1, wherein the support
member comprises at least one embedded insert formed from a
material having a different coefficient of thermal conductivity
than a material of an adjacent region of the support member.
23. The substrate pedestal assembly of claim 22, wherein the
material of the at least one embedded insert has a lower
coefficient of thermal conductivity than the material of the
adjacent region of the support member.
24. The substrate pedestal assembly of claim 22, wherein the
material of the at least one embedded insert has an anisotropic
coefficient of thermal conductivity.
25. The substrate pedestal assembly of claim 1, wherein a support
member is an electrostatic chuck.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/960,874, filed Oct. 7, 2004, which is incorporated by
reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention generally relate to
semiconductor substrate processing systems. More specifically, the
invention relates to a method and apparatus for controlling
temperature of a substrate in a semiconductor substrate processing
system.
[0004] 2. Description of the Related Art
[0005] In manufacture of integrated circuits, precise control of
various process parameters is required for achieving consistent
results within a substrate, as well as the results that are
reproducible from substrate to substrate. During processing,
changes in the temperature and temperature gradients across the
substrate may be detrimental to material deposition, etch rate,
step coverage, feature taper angles, and other parameters of
semiconductor devices. As such, generation of the pre-determined
pattern of temperature distribution across the substrate is one of
critical requirements for achieving high yield.
[0006] In some processing applications, a substrate is retained to
a substrate pedestal by an electrostatic chuck during processing.
The electrostatic chuck is coupled to a base of the pedestal by
clamps, adhesive or fasteners. The chuck may be provided with an
embedded electric heater, as well as be fluidly coupled to a source
of backside heat transfer gas for controlling substrate temperature
during processing. However, conventional substrate pedestals have
insufficient means for controlling substrate temperature
distribution across the diameter of the substrate. The inability to
control substrate temperature uniformity has an adverse effect on
process uniformity both within a single substrate and between
substrates, device yield and overall quality of processed
substrates.
[0007] Therefore, there is a need in the art for an improved method
and apparatus for controlling temperature of a substrate during
processing the substrate in a semiconductor substrate processing
apparatus.
SUMMARY OF THE INVENTION
[0008] The present invention generally is a method and apparatus
for controlling temperature of a substrate during processing the
substrate in a semiconductor substrate processing apparatus. The
method and apparatus enhances temperature control across the
diameter of a substrate, and may be utilized in etch, deposition,
implant, and thermal processing systems, among other applications
where the control of the temperature profile of a workpiece is
desirable.
[0009] In one embodiment of the invention, a substrate pedestal
assembly is provided. The pedestal assembly includes a support
member that is coupled to a base using a material layer. The
material layer has at least two regions having different
coefficients of thermal conductivity. In another embodiment, the
support member is an electrostatic chuck. In further embodiments, a
pedestal assembly has channels formed between the base and support
member for providing cooling gas in proximity to the material layer
to further control heat transfer between the support member and the
base, thereby facilitating control of the temperature profile of a
substrate disposed on the support member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] 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.
[0011] FIG. 1A is a schematic diagram of an exemplary semiconductor
substrate processing apparatus comprising a substrate pedestal in
accordance with one embodiment of the invention;
[0012] FIGS. 1B-1C are partial cross-sectional views of embodiments
of a substrate pedestal having gaps formed in different locations
in a material layer of the substrate pedestal.
[0013] FIG. 2 is a schematic cross-sectional view of the substrate
pedestal taken along a line 2-2 of FIG. 1A;
[0014] FIG. 3 is a schematic partial cross-sectional view of
another embodiment of the invention;
[0015] FIG. 4 is a schematic partial cross-sectional view of
another embodiment of the invention; and
[0016] FIG. 5 is a schematic partial cross-sectional view of yet
another embodiment of the invention; and
[0017] FIG. 6 is a flow diagram of one embodiment of a method for
controlling temperature of a substrate disposed on a substrate
pedestal.
[0018] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures.
DETAILED DESCRIPTION
[0019] The present invention generally is a method and apparatus
for controlling temperature of a substrate during processing.
Although invention is illustratively described in a semiconductor
substrate processing apparatus, such as, e.g., a processing reactor
(or module) of a CENTURA.RTM. integrated semiconductor wafer
processing system, available from Applied Materials, Inc. of Santa
Clara, Calif., the invention may be utilized in other processing
systems, including etch, deposition, implant and thermal
processing, or in other application where control of the
temperature profile of a substrate or other workpiece is
desirable.
[0020] FIG. 1 depicts a schematic diagram of an exemplary etch
reactor 100 having one embodiment of a substrate pedestal assembly
116 that may illustratively be used to practice the invention. The
particular embodiment of the etch reactor 100 shown herein is
provided for illustrative purposes and should not be used to limit
the scope of the invention.
[0021] Etch reactor 100 generally includes a process chamber 110, a
gas panel 138 and a controller 140. The process chamber 110
includes a conductive body (wall) 130 and a ceiling 120 that
enclose a process volume. Process gasses are provided to the
process volume of the chamber 110 from the gas panel 138.
[0022] The controller 140 includes a central processing unit (CPU)
144, a memory 142, and support circuits 146. The controller 140 is
coupled to and controls components of the etch reactor 100,
processes performed in the chamber 110, as well as may facilitate
an optional data exchange with databases of an integrated circuit
fab.
[0023] In the depicted embodiment, the ceiling 120 is a
substantially flat dielectric member. Other embodiments of the
process chamber 110 may have other types of ceilings, e.g., a
dome-shaped ceiling. Above the ceiling 120 is disposed an antenna
112 comprising one or more inductive coil elements (two co-axial
coil elements 112A and 112B are illustratively shown). The antenna
112 is coupled, through a first matching network 170, to a
radio-frequency (RF) plasma power source 118.
[0024] In one embodiment, the substrate pedestal assembly 116
includes a support member 126, a thermoconductive layer 134, a base
114, a collar ring 152, a joint ring 154, a spacer 178, a ground
sleeve 164 and a mount assembly 162. The mounting assembly 162
couples the base 114 to the process chamber 110. The base 114 is
generally formed from ceramic or similar dielectric material. In
the depicted embodiment, the base 114 further comprises at least
one optional embedded heater 158 (one heater 158 is illustratively
shown), at least one optional embedded insert 168 (one annular
insert 168 is illustratively shown), and a plurality of optional
conduits 160 fluidly coupled to a source 182 of a heating or
cooling liquid. In this embodiment, the base 114 is further
thermally separated from the ground sleeve 164 using an optional
spacer 178.
[0025] The conduits 160 and heater 158 may be utilized to control
the temperature of the base 114, thereby heating or cooling the
support member 126, thereby controlling, in part, the temperature
of a substrate 150 disposed on the support member 126 during
processing.
[0026] The insert 168 is formed from a material having a different
coefficient of thermal conductivity than the material of the
adjacent regions of the base 114. Typically, the inserts 168 has a
smaller coefficient of thermal conductivity than the base 114. In a
further embodiment, the inserts 168 may be formed from a material
having an anisotropic (i.e. direction-dependent coefficient of
thermal conductivity). The insert 168 functions to locally change
the rate of heat transfer between the support member 126 through
the base 114 to the conduits 160 relative to the rate of heat
transfer though neighboring portions of the base 114 not having an
insert 168 in the heat transfer path. Thus, by controlling the
number, shape, size, position and coefficient of heat transfer of
the inserts, the temperature profile of the support member 126, and
the substrate 150 seated thereon, may be controlled. Although the
insert 168 is depicted in FIG. 1 shaped as an annular ring, the
shape of the insert 168 may take any number of forms.
[0027] The thermoconductive layer 134 is disposed on a chuck
supporting surface 180 of the base 114 and facilitates thermal
coupling (i.e., heat exchange) between the support member 126 and
the base 114. In one exemplary embodiment, the thermoconductive
layer 134 is an adhesive layer that mechanically bonds the support
member 126 to member supporting surface 180. Alternatively (not
shown), the substrate pedestal assembly 116 may include a hardware
(e.g., clamps, screws, and the like) adapted for fastening the
support member 126 to the base 114. Temperature of the support
member 126 and the base 114 is monitored using a plurality of
sensors (not shown), such as, thermocouples and the like, that are
coupled to a temperature monitor 174.
[0028] The support member 126 is disposed on the base 114 and is
circumscribed by the rings 152, 154. The support member 126 may be
fabricated from aluminum, ceramic or other materials suitable for
supporting the substrate 150 during processing. The substrate 150
may rest upon the support member 126 by gravity, or alternatively
be secured thereto by vacuum, electrostatic force, mechanical
clamps and the like. The embodiment depicted in FIG. 1, the support
member 126 is an electrostatic chuck 188.
[0029] The electrostatic chuck 188 is generally formed from ceramic
or similar dielectric material and comprises at least one clamping
electrode (not shown) controlled using a power supply 128. In a
further embodiment, the electrostatic chuck 188 may comprise at
least one RF electrode (not shown) coupled, through a second
matching network 124, to a power source 122 of substrate bias, and
may also include at least one embedded heater (not shown)
controlled using a power supply 132.
[0030] The electrostatic chuck 188 may further comprise a plurality
of gas passages (not shown), such as grooves, that are formed in a
substrate supporting surface 176 of the chuck and fluidly coupled
to a source 148 of a heat transfer (or backside) gas. In operation,
the backside gas (e.g., helium (He)) is provided at controlled
pressure into the gas passages to enhance the heat transfer between
the electrostatic chuck 188 and the substrate 150. Conventionally,
at least the substrate supporting surface 176 of the electrostatic
chuck is provided with a coating resistant to the chemistries and
temperatures used during processing the substrates.
[0031] In one embodiment, the support member 126 comprises at least
one embedded insert 166 (one annular insert 166 is illustratively
shown) formed from at least one material having a different
coefficient of thermal conductivity than the material(s) of
adjacent regions of the support member 126. Typically, the inserts
166 are formed from materials having a smaller coefficient of
thermal conductivity than the material(s) of the adjacent regions.
In a further embodiment, the inserts 166 may be formed from
materials having an anisotropic coefficient of thermal
conductivity. In an alternate embodiment (not shown), at least one
insert 166 may be disposed coplanar with the substrate supporting
surface 176.
[0032] As with the inserts 168 of the base 114, the thermal
conductivity, as well as the shape, dimensions, location, and
number of inserts 166 in the support member 126 may be selectively
chosen to control the heat transfer through the pedestal assembly
116 to achieve, in operation, a pre-determined pattern of the
temperature distribution on the substrate supporting surface 176 of
the support member 126 and, as such, across the diameter of the
substrate 150.
[0033] The thermoconductive layer 134 comprises a plurality of
material regions (two annular regions 102, 104 and circular region
106 are illustratively shown), at least two of which having
different coefficients of thermal conductivity. Each region 102,
104, 108 may be formed from at least one material having a
different coefficient of thermal conductivity than the material(s)
of adjacent regions of the thermoconductive layer 134. In a further
embodiment, one or more of the materials comprising the regions
102, 104, 106 may have an anisotropic coefficient of thermal
conductivity. For example, coefficients of thermal conductivity of
materials in the layer 134 in the directions orthogonal or parallel
to the member supporting surface 180 may differ from the
coefficients in at least one other direction. The coefficient of
thermal conductivity between the regions 102, 104, 106 of the layer
134 may be selected to promote laterally different rates of heat
transfer between the chuck 126 and base 114, thereby controlling
the temperature distribution across the diameter of the substrate
150.
[0034] In yet further embodiment, gaps 190 (as shown in FIG. 2A)
maybe provided between at least two adjacent regions of the
thermoconductive layer 134. In the layer 134, such gaps 190 may
form either gas-filled or vacuumed volumes having pre-determined
form factors. A gap 190 may alternatively be formed within a region
of the layer 134 (as shown in FIG. 1C).
[0035] FIG. 2 depicts a schematic cross-sectional view of the
substrate pedestal taken along a line 2-2 in FIG. 1A. In the
depicted embodiment, the thermoconductive layer 134 illustratively
comprises the annular regions 102, 104 and the circular region 106.
In alternate embodiments, the layer 134 may comprise either more or
less than three regions, as well as regions having different form
factors, for example, the regions may be arranged as grids,
radially oriented shapes, and polar arrays among others. The
regions of the thermoconductive layer 134 may be composed from
materials (e.g., adhesive materials) applied in a form of a paste
that is further developed into a hard adhesive compound, as well as
in a form of an adhesive tape or an adhesive foil. Thermal
conductivity of the materials in the thermoconductive layer 134 may
be selected in a range from 0.01 to 200 W/mK and, in one exemplary
embodiment, in a range from 0.1 to 10 W/mK. In yet another
embodiment, the adjacent regions have a difference in thermal
conductivities in the range of about 0.1 to 10 W/mK, and may have a
difference in conductivity between an inner most and out most
regions of the layer 134 of about 0.1 to about 10 W/mK. Examples of
suitable adhesive materials include, but not limited to, pastes and
tapes comprising acrylic and silicon based compounds. The adhesive
materials may additionally include at least one thermally
conductive ceramic filler, e.g., aluminum oxide (Al.sub.2O.sub.3),
aluminum nitride (AlN), and titanium diboride (TiB.sub.2), and the
like. One example of an adhesive tape suitable for the conductive
layer 134 is sold under the tradename THERMATTACH.RTM., available
from Chomerics, a division of Parker Hannifin Corporation, located
in Wolburn, Mass.
[0036] In the thermoconductive layer 134, the thermal conductivity,
as well as the form factor, dimensions, and a number of regions
having the pre-determined coefficients of thermal conductivity may
be selectively chosen to control the heat transfer between the
electrostatic chuck 126 and the base 114 to achieve, in operation,
a pre-determined pattern of the temperature distribution on the
substrate supporting surface 176 of the chuck and, as such, in the
substrate 150. To further control the heat transfer through the
conductive layer 134 between the base 114 and support member 126,
one or more channels 108 are provided to flow a heat transfer
medium therethrough. The channels 108 are coupled through the base
114 to a source 150 of heat transfer medium, such as a cooling gas.
Some examples of suitable cooling gases include helium and
nitrogen, among others. As the cooling gas disposed in the channels
108 is part of the heat transfer path between the chuck 126 and
base 114, the position of the channels 108, and the pressure, flow
rate, temperature, density and composition of the heat transfer
medium of cooling gas provided, provides enhanced control of the
heat transfer profile through the pedestal assembly 116. Moreover,
as the density and flow rate of gas in the channel 108 may be
controlled in-situ during processing of substrate 150, the
temperature control of the substrate 150 may be changed during
processing to further enhance processing performance. Although a
single source 156 of cooling gas is shown, it is contemplated that
one or more sources of cooling gas may be coupled to the channels
108 in a manner such that the types, pressures and/or flow rate of
cooling gases within individual channels 108 may be independently
controller, thereby facilitating an even greater level of
temperature control.
[0037] In the embodiment depicted in FIG. 1A, the channels 108 are
depicted as formed in the member supporting surface 180. However,
it is contemplated that the channels 108 may be formed at least
partially in the member supporting surface 180, at least partially
in the bottom surface of the support member 126, or at least
partially in the thermally conductive layer 134, along with
combinations thereof. In one embodiment, between about 2 to 10
channels 108 are disposed in the pedestal assembly 116 and provide
with the selectivity maintained at a pressure between about 760
Torr (atmospheric pressure) to about 10 Torr. For example, at least
one of the channels 108 may be partially or entirely formed in the
electrostatic chuck 126, as illustrated in FIGS. 3-4. More
specifically, FIG. 3 depicts a schematic diagram of a portion of
the substrate pedestal assembly 116 where the channels 108 are
formed entirely in the electrostatic chuck 126. FIG. 4 depicts a
schematic diagram of a portion of the substrate pedestal assembly
116 where the channels 108 are partially formed in the base 114
and, partially, in the electrostatic chuck 126. FIG. 5 depicts a
schematic diagram of a portion of the substrate pedestal assembly
116 where the channels 108 are formed in the thermoconductive layer
134. Although in FIG. 5 the channels are shown disposed between
different regions 102, 104, 106 of the thermoconductive layer 134,
the one or more of the channels may be formed through one or more
of the regions 102, 104, 106.
[0038] Returning to FIG. 1A, at least one of the location, shape,
dimensions, and number of the channels 108 and inserts 166, 168 as
well as the thermal conductivity of the inserts 166, 168 and gas
disposed in the channels 108, may be selectively chosen to control
the heat transfer between the support member 126 to the base 114 to
achieve, in operation, a pre-determined pattern of the temperature
distribution on the substrate supporting surface 176 of the chuck
126 and, as such, control the temperature profile of the substrate
150. In further embodiments, the pressure of the cooling gas in at
least one channel 108, as well as the flow of the cooling liquid in
at least one conduit 156 may also be selectively controlled to
achieve and/or enhance temperature control of the substrate. The
heat transfer rate may also be controlled by individually
controlling the type of gas, pressure and/or flow rate between
respective channels 108.
[0039] In yet further embodiments, the pre-determined pattern of
the temperature distribution in the substrate 150 may be achieved
using individual or combinations of the described control means,
e.g., the thermoconductive layer 134, the inserts 166, 168,
channels 108, conduits 160, the pressure of cooling gas in the
channels 108, and the flow of the cooling liquid in the conduits
160. Furthermore, in the discussed above embodiments,
pre-determined patterns of the temperature distribution on the
substrate supporting surface 176 and in the substrate 150 may
additionally be selectively controlled to compensate for
non-uniformity of the heat fluxes originated, during processing the
substrate 150, by a plasma of the process gas and/or substrate
bias.
[0040] FIG. 6 depicts a flow diagram of one embodiment of an
inventive method for controlling temperature of a substrate
processed in a semiconductor substrate processing apparatus as a
process 600. The process 600 illustratively includes the processing
steps performed upon the substrate 150 during processing in the
reactor 100 described in the embodiments above. It is contemplated
that the process 600 may be performed in other processing
systems.
[0041] The process 600 starts at step 601 and proceeds to step 602.
At step 602, the substrate 150 is transferred to the pedestal
assembly 116 disposed in the process chamber 110. At step 604, the
substrate 150 is positioned (e.g., using a substrate robot, not
shown) on the substrate supporting surface 176 of the electrostatic
chuck 188. At step 606, the power supply 132 engages the
electrostatic chuck 188 to clamp the substrate 150 to the
supporting surface 176 of the chuck 188. At step 608, the substrate
150 is processed (e.g., etched) in the process chamber 110 in
accordance with a process recipe executed as directed by the
controller 140. During step 608, the substrate pedestal assembly
116 facilitates a pre-determined pattern of temperature
distribution in the substrate 150, utilizing one or more of the
temperature control attributes of the pedestal assembly 116
discussed in reference to FIGS. 1-5 above. Optionally, the rate
and/or profile of heat transferred through the chuck 114 during
step 608 may be adjusted in-situ by changing one or more of the
characteristics of the gas present in one or more of the channels
108. Upon completion of processing, at step 610, the power supply
132 disengages the electrostatic chuck 188 and, as such, de-chucks
the substrate 150 that is further removed from the process chamber
110. At step 612, the process 600 ends.
[0042] 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.
* * * * *