U.S. patent application number 14/087976 was filed with the patent office on 2014-03-27 for temperature controlled plasma processing chamber component with zone dependent thermal efficiences.
The applicant listed for this patent is Kallol Bera, Larry D. Elizaga, Chetan Mahadeswaraswamy. Invention is credited to Kallol Bera, Larry D. Elizaga, Chetan Mahadeswaraswamy.
Application Number | 20140083978 14/087976 |
Document ID | / |
Family ID | 45095390 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140083978 |
Kind Code |
A1 |
Mahadeswaraswamy; Chetan ;
et al. |
March 27, 2014 |
TEMPERATURE CONTROLLED PLASMA PROCESSING CHAMBER COMPONENT WITH
ZONE DEPENDENT THERMAL EFFICIENCES
Abstract
Components and systems for controlling a process or chamber
component temperature as a plasma process is executed by plasma
processing apparatus. A first heat transfer fluid channel is
disposed in a component subjacent to a working surface disposed
within a plasma processing chamber such that a first length of the
first channel subjacent to a first temperature zone of the working
surface comprises a different heat transfer coefficient, h, or heat
transfer area, A, than a second length of the first channel
subjacent to a second temperature zone of the working surface. In
embodiments, different heat transfer coefficients or heat transfer
areas are provided as a function of temperature zone to make more
independent the temperature control of the first and second
temperature zones.
Inventors: |
Mahadeswaraswamy; Chetan;
(Sunnyvale, CA) ; Bera; Kallol; (San Jose, CA)
; Elizaga; Larry D.; (Tracy, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mahadeswaraswamy; Chetan
Bera; Kallol
Elizaga; Larry D. |
Sunnyvale
San Jose
Tracy |
CA
CA
CA |
US
US
US |
|
|
Family ID: |
45095390 |
Appl. No.: |
14/087976 |
Filed: |
November 22, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13111384 |
May 19, 2011 |
8608852 |
|
|
14087976 |
|
|
|
|
61354158 |
Jun 11, 2010 |
|
|
|
Current U.S.
Class: |
216/67 ;
118/723R; 156/345.27; 165/104.14 |
Current CPC
Class: |
H01L 21/67248 20130101;
H01L 21/67109 20130101; F28D 2021/0028 20130101; H01J 37/32724
20130101; F28F 7/02 20130101; H01L 21/67069 20130101; H01J 37/32908
20130101; H01J 37/32522 20130101; H01J 37/02 20130101 |
Class at
Publication: |
216/67 ;
156/345.27; 118/723.R; 165/104.14 |
International
Class: |
H01J 37/02 20060101
H01J037/02 |
Claims
1. A plasma processing apparatus, comprising: a plasma power source
coupled to the process chamber to energize a plasma during
processing of a workpiece disposed in the process chamber; a
process chamber including a temperature-controlled component
coupled to a heat source or sink by a first heat transfer fluid
loop, the first fluid loop passing through first and second lengths
of a channel embedded in the temperature-controlled component,
wherein the first length is subjacent to a first temperature zone
of the component and the second length is subjacent a second
temperature zone of the component, wherein the first length
comprises a lower heat transfer coefficient and/or heat transfer
area than the second length.
2. The plasma processing apparatus of claim 1, wherein the
temperature-controlled component is a gas distribution showerhead
or a substrate supporting chuck, wherein the first temperature zone
comprises an annular portion of the showerhead or chuck surrounding
the second temperature zone and wherein the showerhead or chuck is
further coupled to a second heat transfer fluid loop, the second
fluid loop passing through a third length of a channel embedded in
the temperature-controlled component subjacent to the first
temperature zone of the component.
3. The plasma processing apparatus of claim 2, wherein the first
length has a lower heat transfer coefficient or heat transfer area
than both the second and third lengths.
4. The plasma processing apparatus of claim 3, wherein the heat
transfer coefficient along the first length is lower than the
second length.
5. The plasma processing apparatus of claim 3, wherein the heat
transfer area along the first length is lower than the second
length.
6. The plasma processing apparatus of claim 3, wherein the first
length has a first cross-sectional area larger than a second
cross-sectional area of the second length.
7. A method of controlling a temperature of a working surface in a
plasma processing apparatus, comprising: flowing a first heat
transfer fluid through a first and second length of a first heat
transfer fluid channel, wherein the first length is subjacent to an
outer temperature zone of the working surface and wherein the
second length is subjacent to an inner temperature zone of the
working surface, the outer temperature zone forming an annulus
about the inner temperature zone; flowing a second heat transfer
fluid through a second heat transfer fluid channel, wherein the
second heat transfer fluid channel is subjacent to the outer
temperature zone of the working surface; and modulating a flow rate
of the first heat transfer fluid to control the temperature of the
inner temperature zone without affecting the temperature of the
outer temperature zone.
8. The method of claim 7, further comprising delivering a process
gas through the component and conducting a plasma etch process of a
workpiece while modulating the flow rate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional of application Ser. No.
13/111,384 filed May 19, 2011 which claims the benefit of U.S.
Provisional Application No. 61/354,158 filed Jun. 11, 2010,
entitled "TEMPERATURE CONTROLLED PLASMA PROCESSING CHAMBER
COMPONENT WITH ZONE DEPENDENT THERMAL EFFICIENCIES," the entire
contents of which are hereby incorporated by reference in its
entirety for all purposes.
BACKGROUND
[0002] 1) Field
[0003] Embodiments of the present invention generally relate to
plasma processing equipment, and more particularly to methods of
controlling temperatures during processing of a workpiece within a
plasma processing chamber.
[0004] 2) Description of Related Art
[0005] In a plasma processing chamber, such as a plasma etch or
plasma deposition chamber, the temperature of a chamber component
is often an important parameter to control during a process. For
example, a temperature of a substrate holder, commonly called a
chuck or pedestal, may be controlled to heat/cool a workpiece to
various controlled temperatures during the process recipe (e.g., to
control an etch rate). Similarly, a temperature of a
showerhead/upper electrode or other component may also be
controlled during the process recipe to influence the processing
(e.g., etch rate uniformity).
[0006] Often, various constraints on design of a plasma processing
chamber necessitate introducing a heat transfer media to a
temperature controlled component in a manner which results in heat
transfer within portions of the component that are not desired. For
example, where a process gas distribution showerhead or workpiece
chuck has a plurality of zones which can be independently
controlled to separate setpoint temperatures or to better manage
disparate heat loads between the zones, a heat transfer media
utilized for control of a first temperature zone (i.e., a target
zone) may also pass proximate to a second temperature zone (i.e., a
collateral zone) en route to, or from, the target temperature zone.
As such, driving the plurality of temperature zones independently
can introduce significant cross-talk between the zones as well as
significant temperature non-uniformity within the collateral
zone.
SUMMARY
[0007] Components and systems for controlling a process or chamber
component temperature as a plasma process is executed by plasma
processing apparatus are described herein. In certain embodiments,
plasma processing chamber component having a working surface is
disposed within a plasma processing chamber. A first heat transfer
fluid channel is disposed in the component subjacent to the working
surface such that a first length of the first channel subjacent to
a first zone of the working surface comprises a different heat
transfer coefficient, h, or heat transfer area, A, than a second
length of the first channel subjacent to a second zone of the
working surface. For example, where the second length is downstream
of the first length, the first length has a lower heat transfer
coefficient h than does the second length so that the first heat
transfer fluid has a lesser impact (e.g., reduced heat transfer
rate {dot over (Q)}) on the first zone temperature than the first
heat transfer fluid does on the second zone. In embodiments,
different heat transfer coefficients or heat transfer areas are
provided as a function of temperature zone to make more independent
the temperature control of the first and second temperature
zones.
[0008] In a further embodiment, where the component includes a
second heat transfer fluid channel disposed subjacent to the first
zone of the working surface, the heat transfer coefficient or heat
transfer area along a length of the second channel is made greater
than that of the first length of the first channel so that a second
heat transfer fluid passing through the second channel may have a
greater impact on the first zone temperature than does the first
heat transfer fluid passing through the first length of the first
channel. In one exemplary embodiment, where the component is a
substrate chuck or process gas showerhead, the working surface is
circular and the first zone comprises an annular portion of the
circular working surface which surrounds the second zone.
[0009] In certain embodiments, the lengths of heat transfer fluid
channels are engineered to modulate one of a heat transfer
coefficient or heat transfer area. In one particular embodiment,
the heat transfer coefficient along the first length is made lower
than the second length through incorporation of a sleeve of a
thermally resistive material about the first length of channel to
increase the thermal resistance relative to the second length. In
another embodiment, a first length of the first channel is disposed
at a greater distance subjacent to the working surface along the
first length than along the second length and/or at a greater
distance than is a length of the second heat transfer fluid
channel. A thermal break, such as an evacuate space or non-metallic
material may in addition, or in the alternative, be disposed
between the first channel and the working surface along at least a
portion of the first length to increase the thermal resistance
relative to the second length.
[0010] In embodiments, the heat transfer area along the first
length is made lower than the second length, for example through
incorporation of fins along the second length that are absent in
the first length.
[0011] Embodiments include a plasma processing chamber, such as a
plasma etch or plasma deposition system, having a
temperature-controlled component to be coupled to a heat sink/heat
source. The temperature-controlled component may be coupled to a
first heat sink/source by a first heat transfer fluid loop, the
first fluid loop passing through first and second lengths of a
channel embedded in first and second zones of the
temperature-controlled component, respectively. The
temperature-controlled component may be further coupled to a second
heat sink/source by a second heat transfer fluid loop, the second
fluid loop passing through channel lengths embedded only in the
first zone. The first length of the first channel may have a heat
transfer coefficient or heat transfer area different than that of
the second length and/or second channel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Embodiments of the invention are particularly pointed out
and distinctly claimed in the concluding portion of the
specification. Embodiments of the invention, however, both as to
organization and method of operation, together with objects,
features, and advantages thereof, may best be understood by
reference to the following detailed description when read with the
accompanying drawings in which:
[0013] FIG. 1A is a layout view of a temperature controlled plasma
processing chamber component comprising a working surface having a
plurality of temperature zones, in accordance with an embodiment of
the present invention;
[0014] FIGS. 1B and 1C are plan views of the temperature controlled
plasma processing chamber component illustrated in FIG. 1A,
illustrating working surface temperature variations in a first
zone, in accordance with an embodiments of the present
invention
[0015] FIG. 2A illustrates a cross-sectional view along the A-A'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0016] FIG. 2B illustrates a cross-sectional view along the B-B'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0017] FIG. 3A illustrates a cross-sectional view along the A-A'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0018] FIG. 3B illustrates a cross-sectional view along the B-B'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0019] FIG. 4A illustrates a cross-sectional view along the A-A'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0020] FIG. 4B illustrates a cross-sectional view along the B-B'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0021] FIG. 5A illustrates a cross-sectional view along the A-A'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0022] FIG. 5B illustrates a cross-sectional view along the B-B'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0023] FIG. 6A illustrates a cross-sectional view along the A-A'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0024] FIG. 6B illustrates a cross-sectional view along the B-B'
line of the temperature controlled plasma processing chamber
component depicted in FIG. 1, in accordance with an embodiment of
the present invention;
[0025] FIG. 7 illustrates a schematic of a plasma etch system
including a temperature controlled process gas showerhead, in
accordance with an embodiment of the present invention; and
[0026] FIG. 8 illustrates a schematic of a plasma etch system
including a temperature controlled substrate supporting chuck, in
accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
[0027] In the following detailed description, numerous specific
details are set forth in order to provide a thorough understanding
of embodiments of the invention. However, it will be understood by
those skilled in the art that other embodiments may be practiced
without these specific details. In other instances, well-known
methods, procedures, components and circuits have not been
described in detail so as not to obscure the present invention.
[0028] The terms "coupled" and "connected," along with their
derivatives, may be used herein to describe structural
relationships between components. It should be understood that
these terms are not intended as synonyms for each other. Rather, in
particular embodiments, "connected" may be used to indicate that
two or more elements are in direct physical or electrical contact
with each other. "Coupled" my be used to indicated that two or more
elements are in either direct or indirect (with other intervening
elements between them) physical or electrical contact with each
other, and/or that the two or more elements co-operate or interact
with each other (e.g., as in a cause and effect relationship).
[0029] Described herein are plasma chamber components including a
first heat transfer fluid channel in which a portion of the channel
disposed outside of a target temperature zone of the component is
designed to have a lower heat transfer coefficient h or heat
transfer area A than a portion of the first channel disposed within
the target zone of the component. By reducing the heat transfer
coefficient h and/or heat transfer area A, the effect of the heat
transfer fluid flowing through the first channel portion outside of
the target zone on the temperature of a working surface of the
component outside of the target zone may be reduced even if the
thermodynamic driving force .DELTA.T is largest outside of the
target temperature zone. This is particularly advantageous for
plasma chamber components that include a second
temperature-controlled zone through which the first heat transfer
fluid channel passes through to access the target zone. As such, a
temperature of a working surface in the second zone is made less of
a function of the first heat transfer fluid channel and uniformity
of the surface temperature within the second zone may be
improved.
[0030] In an embodiment, a temperature-controlled plasma processing
chamber component includes a working surface disposed within a
plasma processing chamber, such as the plasma etch systems depicted
further in FIGS. 7 and 8. FIG. 1A is a layout view of exemplary
temperature-controlled plasma processing chamber component 100, in
accordance with an embodiment of the present invention. In a first
exemplary embodiment, as further illustrated in FIG. 7, the
component 100 is a process gas distribution showerhead through
which a process gas may be provided to a plasma processing chamber.
In a second exemplary embodiment, as further illustrated in FIG. 8,
the component 100 is a workpiece supporting chuck or pedestal upon
which a workpiece is disposed during a plasma processing operation.
In still another embodiment, a temperature-controlled plasma
processing chamber component adapted to provide the
features/functionality described herein for the exemplary
embodiments includes a chamber wall liner.
[0031] For the first and second exemplary embodiments, the
component 100 includes a circular working surface 126 which may be
exposed to the plasma (e.g. for a showerhead embodiment) or may be
supporting a workpiece (e.g., for a chuck embodiment). In FIG. 1A,
the working surface 126 may be considered transparent for the
purpose of visualizing heat transfer fluid channels subjacent to
(below) the working surface 126. The working surface 126 however is
typically to be of a semiconductor (e.g., silicon) an anodized
surface (e.g., Al.sub.2O.sub.3), a ceramic (e.g., ytterium oxides),
or any other material conventional to a plasma processing
apparatus. As illustrated, the temperature zone 105 has an annular
shape while the temperature zone 110 is circular in shape and
encircled or circumscribed by the temperature zone 105 to form
"inner" and "outer" temperature zones of the component 100. The
annular arrangement of the zones 105 and 110 is a function of the
cylindrical symmetry of a plasma processing apparatus configured to
process disk-shaped wafer substrates conventional in the
semiconductor/microelectronic/electro-optical manufacturing art and
it should be appreciated that in other embodiments two temperature
zones may merely be adjacent (e.g., for in-line plasma processing
apparatuses conventional in photovoltaic manufacture, etc.).
[0032] In an embodiment, a temperature-controlled plasma processing
chamber component includes at least one heat transfer fluid channel
subjacent to a working surface 126 and forming a portion of a heat
transfer fluid loop coupled to the plasma processing apparatus. The
heat transfer fluid may be any heat transfer fluid known in the art
to be suitable for the purpose(s) of transferring heat to/from the
component 100 (specifically the working surface 126 where a heat
load will be placed) for the purpose of controlling one or more of
the plurality of temperature zones. Examples of suitable heat
transfer fluids include water-based mixtures, such as Galden.RTM.
(available from Solvay S. A.) or Fluorinert.TM. (available from 3M
Company). In the exemplary embodiment depicted, a first heat
transfer fluid channel includes a plurality of fluid channel
lengths 112A, 113A and 114A. As depicted, heat transfer fluid 1
flows into the component 100, through a first channel length 112A,
to a second channel length 113A downstream of the first channel
length 112A, to a third channel length 114A downstream of the
second channel length 113A, and out of the component 100. The
channel lengths 112A, 113A, 114A are embedded within the component
100 to be subjacent to the working surface 126.
[0033] In an embodiment, a temperature-controlled plasma processing
chamber component includes a plurality of temperature zones.
Generally, the temperature zones are adjacent/circumjacent regions
of a working surface to be disposed within a plasma processing
chamber and the temperature zones are controllable to a setpoint
temperature independent of one another. Independence of the
temperature zones prevents different heat transfer fluid flows
within the different zones (as provided to control a target zone's
temperature) from affecting the temperature another zone (e.g.,
collateral zone). For example, where some form of
feedback/feedforward control is utilized and according to the
control algorithm a first zone required a large heat transfer fluid
flow and a second required no heat transfer fluid flow then the
large flow through the heat transfer fluid channel accessing the
first zone via the second zone should not alter the temperature of
the second zone.
[0034] The temperature zone for which a particular heat transfer
fluid controls (i.e., target zone) is a function of the heat
transfer rate {dot over (Q)} provided by the heat transfer fluid
passing through a particular heat transfer fluid channel within
that zone, with fluid channels that provide a higher heat transfer
rate {dot over (Q)} applying a larger control effort at a
particular location on the working surface 126. Generally, the
larger the disparity in heat transfer rate {dot over (Q)} a heat
transfer fluid has between different temperature zones (e.g., {dot
over (Q)}.sub.zone 1 to {dot over (Q)}.sub.zone 2), the lower the
cross-talk, and greater the temperature independence of adjacent
zones. Consider a heat transfer matrix between a first temperature
zone and a second temperature zone:
{dot over (Q)}.sub.11 {dot over (Q)}.sub.12
{dot over (Q)}.sub.21 {dot over (Q)}.sub.22'
where {dot over (Q)}.sub.11 represents a first heat transfer fluid
affect on zone 1, {dot over (Q)}.sub.12 represents the first heat
transfer fluid affect on the second zone, {dot over (Q)}.sub.21
represents the second heat transfer fluid affect on the first zone
and {dot over (Q)}.sub.22 represents the second heat transfer fluid
affect on the second zone. The crosstalk terms {dot over
(Q)}.sub.12 and {dot over (Q)}.sub.21 are to be minimized while
maximizing {dot over (Q)}.sub.11 and {dot over (Q)}.sub.22 for
independent temperature control of each zone (e.g., via a
feedforward and/or feedback mechanism).
[0035] In one embodiment, a plurality of temperature zones is
provided via a plurality of heat transfer elements within the
temperature-controlled component. A heat transfer element may be
any known in the art, such as a heat transfer fluid channel, a
thermoelectric (TE) element, a resistive heating element, etc. In
the exemplary embodiment including a first heat transfer fluid
channel, a plurality of temperature zones may be provided by adding
a second, third, etc. heating element in combination with the first
heat transfer fluid channel. For example, a first heat transfer
fluid channel may be combined with a TE element or a resistive
heating element. For the exemplary embodiment illustrated in FIG.
1A, however, a first heat transfer fluid channel is combined with a
second heat transfer fluid channel 107A to provide the plurality of
temperature zones. More specifically, the second heat transfer
fluid channel 107A is subjacent to the temperature zone 105. As
illustrated, all lengths 132A, 133A and 134A of the second heat
transfer fluid channel 107A are within the temperature zone 105 so
that the fluid 2 feeds into the component 100 and out of the
component 100 without passing through another temperature zone.
[0036] In an embodiment, the temperature-controlled plasma
processing chamber component 100 includes at least one heat
transfer fluid channel having channel lengths within more than one
temperature zone. In the exemplary embodiments represented by FIG.
1A, a first heat transfer fluid channel has channel lengths in both
the temperature zone 105 (e.g., lengths 112A and 114A) and
temperature zone 110 (e.g., length 113A). Thus, at least a feed
and/or a return of the fluid 1 passes through the temperature zone
105. Depending on the path configuration of a heat transfer fluid
channel, a channel length in a first zone (e.g., temperature zone
105) may be approximately equal in length to a channel length in a
second, adjacent zone (e.g., temperature zone 110). Whether the
second temperature zone (e.g., temperature zone 110) is controlled
via a second heat transfer fluid channel or otherwise (e.g., TE
element), having at least one heat transfer fluid channel with
channel lengths within more than one temperature zone may induce
undesirable cross-talk between adjacent temperature zones (e.g.,
large {dot over (Q)}.sub.12 and {dot over (Q)}.sub.21 terms) and
induce significant variation in the temperature of a component's
working surface, as illustrated in FIG. 1B. Nevertheless, other
hardware limitations (e.g., process gas distribution assemblies,
lift pin assemblies, etc.) may motivate such a fluid channel
layout.
[0037] As further illustrated in FIG. 1A, additional heat transfer
fluid channels may be incorporated into the component 100 to
improve surface temperature control (e.g., uniformity of heat
transfer rate). For example, the temperature zone 110 further
includes a third heat transfer fluid channel including lengths
112B, 113B, and 114B disposed in the component 100 in a manner
symmetrical to the lengths 112A, 113A, and 114B about a central
axis 101 of the component (i.e., azimuthally (.theta.) symmetrical)
to provide a second, parallel source of fluid 1 into the
temperature zone 110. Analogously, the temperature zone 105 further
includes a fourth heat transfer fluid channel 107B disposed in the
component 100 in a manner symmetrical to the second heat transfer
fluid channel 107A about a center of the component. For clarity of
discussion, lengths 112A, 113A, 114A, 112B, 113B, and 114B are
referenced in the alternative, as is channel 107A and channel 107B,
with the understanding that characteristics of references numbers
with an "A" suffix are also applicable to the same reference number
with a "B" suffix.
[0038] In embodiments, lengths of a heat transfer fluid channel
within a target temperature zone have a different heat transfer
coefficient h or different heat transfer area A than do lengths of
the heat transfer fluid channel outside of the target temperature
zone (i.e., within a collateral temperature zone). In an
embodiment, a first length of the first channel subjacent to a
first zone of the working surface comprises a different heat
transfer coefficient h than a second length of the first channel
subjacent to a second zone of the working surface. For the
exemplary embodiments represented by FIG. 1A, the heat transfer
coefficient h along the channel length 112A is different than the
heat transfer coefficient h along the channel length 113A. In a
particular embodiment, the heat transfer coefficient h along the
channel length 112A is lower than the heat transfer coefficient h
along the channel length 113A.
[0039] In another embodiment, a first length of the first channel
subjacent to a first zone of the working surface comprises a
different heat transfer area A than a second length of the first
channel subjacent to a second zone of the working surface. For the
exemplary embodiments represented by FIG. 1A, the heat transfer
area A along the channel length 112A is different than the heat
transfer area A along the channel length 113A. In a particular
embodiment, the heat transfer area A along the channel length 112A
is lower than the heat transfer area A along the channel length
113A.
[0040] In further embodiments, the amount by which the heat
transfer coefficient h and/or the heat transfer area A is lower
along the first channel length than the second channel length is
larger than any reduction in .DELTA.T between the two channel
lengths such that a relatively lower heat transfer rate in the
first channel length is achieved even for an upstream length of the
channel where .DELTA.T may be expected to be greater than for a
downstream length. For the exemplary embodiments represented by
FIG. 1A, the product hA along the channel length 112A is lower than
the product hA along the channel length 113A.
[0041] In a further embodiment, a third length of a first heat
transfer fluid channel downstream of the second length and also
subjacent to the first zone has a heat transfer coefficient h or
heat transfer area A that is lower than along the second length.
For example, referring back to FIG. 1B, the length 114A has a lower
heat transfer coefficient h and/or heat transfer area A than along
the length 113A (length within target zone 110). As such, where
either or both the heat transfer coefficient h and/or the heat
transfer area A is reduced sufficiently for a first channel (e.g.,
112A) disposed in a non-targeted zone (e.g., 105), cross-talk with
a second channel (e.g., 107A) disposed subjacent to the first zone
may be reduced and where the second channel is to conduct a second
heat transfer fluid at a second temperature, the temperature of the
working surface (e.g., 126) within the first zone may be made more
uniformly controlled to a setpoint temperature by the second heat
transfer fluid targeted at the first zone (e.g., as depicted in
FIG. 1C).
[0042] FIG. 2A illustrates a cross-sectional view along the A-A'
line of the temperature controlled plasma processing chamber
component 100 depicted in FIG. 1, in accordance with an embodiment
of the present invention. The component 100 is a multi-leveled
assembly including at least a first layer 220 and a second layer
225. Each layer 220 and 225 may, for example, be of a material
conventional to a single level component. In certain embodiments,
the second layer 225 is of a material with high thermal
conductivity to reduce thermal spreading resistance across the
working surface 126. In other embodiments however, the second layer
225 is of a material with low thermal conductivity to localize heat
transfer to regions of the working surface 126 most proximate to a
heat transfer fluid channel.
[0043] The component 100 further includes a plurality of heat
transfer fluid channel levels with the channel length 114A formed
within the layer 220 and the channel length 113A formed within the
layer 225. The first and second heat transfer fluid levels are
interconnected via connectors 228 formed in a capping layer 227. In
a particular embodiment, the component 100 first layer 220 is
machined to form a first pattern of first heat transfer fluid
channel lengths (e.g., length 114A). The capping layer 227 is then
machined to have connectors 228 corresponding to locations of the
first heat transfer fluid channels and then affixed (e.g., brazed,
soldered, thermally bonded, etc.) to the first level 200, thereby
enclosing the first heat transfer fluid channels. The second layer
225 is similarly machined to form a second pattern of second heat
transfer fluid channel lengths (e.g., length 113A) and the second
layer 225 is similarly affixed to the capping layer 227. The
thermal resistance R.sub.1 in the collateral zone (e.g., zone 105)
may be made substantially larger than the thermal resistance
R.sub.2 in the target zone (e.g., zone 110), for example because of
the lower heat transfer coefficient attributable to the larger
distance and/or the additional capping layer 227 (which may be
selected to have a relatively lower thermal conductivity) between
the working surface 126 and the channel length 114A relative to the
channel length 113A.
[0044] As further illustrated in FIG. 2A, the heat transfer
coefficient h and/or heat transfer area A along the length 114A of
the first channel is lower than along an equal length of the second
channel 107A. Where the second channel 107A is targeted to provide
temperature control of the working surface 126 in the zone 105, the
second channel 107A is disposed within the layer 225 to be more
proximate to the working surface 126 than is the length 114. For
embodiments as depicted in FIG. 1A, where the entire second channel
107A is disposed with the zone 105, all lengths 132A, 133A and 134A
may be disposed within the layer 225. However sections 132A and
134A may be in layer 220 as it may affect the symmetry about the
central axis 101 along the azimuth angle .theta..
[0045] FIG. 2B illustrates a cross-sectional view along the B-B'
line of the temperature controlled plasma processing chamber
component 100 depicted in FIG. 1, in accordance with an embodiment
of the present invention. As further illustrated, both the first
and third lengths 112B and 114B of a heat transfer fluid channel
within the non-targeted temperature zone 105 are associated with
larger thermal resistances R1, for example because of the lower
heat transfer coefficient h attributable to the larger distance
and/or the additional capping layer 227 (which may be selected to
have a relatively lower thermal conductivity) between the working
surface 126 and the first and third heat transfer fluid channel
lengths 112B and 114B.
[0046] In an embodiment, a temperature-controlled component
includes a thermal break disposed between a working surface and a
length of a heat transfer fluid channel in a non-targeted
temperature zone to increase the thermal resistance relative to a
second length of the heat transfer fluid channel located within a
target temperature zone. A thermal break comprises a region of a
relatively lower thermal conductivity than the bulk of component
100. FIG. 3A illustrates a cross-sectional view along the A-A' line
of the temperature controlled plasma processing chamber component
100 depicted in FIG. 1, in accordance with an embodiment of the
present invention. As shown, a thermal break 330 is disposed
between at least a portion of the channel length 114A and the
working surface 126 to increase the thermal resistance between the
working surface 126 and a point within the channel length 114A to
R1 relative to the thermal resistance R2 between the working
surface 126 and a point within the channel length 113A. In one
embodiment, the thermal break 330 comprises an evacuated or
rarefied space. The thermal break 330 may be formed as a channel in
the layer 225 in a manner similar to the heat transfer fluid
channel 113A, however the thermal break 330 is sealed by the
capping layer 227 such that no connector 228 is provided subjacent
to the thermal break 330 and a void which is not to conduct a heat
transfer fluid is formed within the layer 225. In other
embodiments, the channel formed in layer 225 is filled with a
material having a lower thermal conductivity than the bulk of the
layer 225, for example a non-metallic material, such as ceramics,
plastics, polyimides, Teflon.RTM., Kapton.RTM., etc. In an
alternative embodiment, the capping layer 227 may further serve the
function of a thermal break either by incorporating a rarefied
space between opposing surfaces of the capping layer 227 (each
mating with one of the layers 220 and 225) or by comprising a
material of relatively lower thermal conductivity.
[0047] FIG. 3B illustrates a cross-sectional view along the B-B'
line of the temperature controlled plasma processing chamber
component 100 depicted in FIG. 1, in accordance with an embodiment
of the present invention. As illustrated, both the first and third
lengths 112B and 114B of a heat transfer fluid channel within the
non-targeted temperature zone 105 are associated with larger
thermal resistances R1, for example because of the lower heat
transfer coefficient h attributable to the thermal break having a
relatively lower thermal conductivity than the bulk of layer 225
between the working surface 126 and the first and third heat
transfer fluid channel lengths 112B and 114B.
[0048] In one embodiment, a heat transfer fluid channel comprises a
number of fins along a length within a target temperature zone that
are absent from a length of the channel outside of the target zone
such that the heat transfer area A is made larger in for the
channel length within the target zone. FIG. 4A illustrates a
cross-sectional view along the A-A' line of the temperature
controlled plasma processing chamber component 100 depicted in FIG.
1, in accordance with an embodiment of the present invention. As
depicted, within the zone 110, the channel length 113A includes a
plurality of topological features 440 (e.g., fins), increasing the
heat transfer area/length (A/L) for a channel length 113A relative
the channel length 114B. As such the cumulative thermal resistance
R2/length along the channel length 113A may be made less than the
thermal resistance R1/length along the channel length 114B. In
certain further embodiments, topological features 440 may also be
provided in a second heat transfer fluid channel 107A.
[0049] FIG. 4B illustrates a cross-sectional view along the B-B'
line of the temperature controlled plasma processing chamber
component 100 depicted in FIG. 1, in accordance with an embodiment
of the present invention. As illustrated, both the first and third
lengths 112B and 114B of a heat transfer fluid channel within the
non-targeted temperature zone 105 are associated with larger
thermal resistances R1, for example because of a lower heat
transfer area/length A/L attributable to the absences of
topological features 440 in heat transfer fluid channel lengths
112B and 114B. As further illustrated in FIGS. 4A and 4B,
modulation of the heat transfer area between lengths of a heat
transfer fluid channel may allow for a simplified assembly
including only the layer 225 and a single level of channels. Of
course, because most any embodiment described herein may be
combined with any other, a multi-level channel configuration (e.g.,
FIGS. 2A-3B) may also be implemented in combination with the
modulation in heat transfer area to increase the disparity in heat
transfer rate between various lengths of the channel.
[0050] In an embodiment a thermally resistive material forms a
sleeve around a heat transfer fluid channel length to increase the
thermal resistance relative to a second length of the channel
lacking such a channel sleeve. FIG. 5A illustrates a
cross-sectional view along the A-A' line of the temperature
controlled plasma processing chamber component 100 depicted in FIG.
1, in accordance with an embodiment of the present invention. As
illustrated, a thermally resistive channel sleeve 550 is present
along at least a portion of the channel length 114B. The thermally
resistive material may, for example be any of those described for
thermal break embodiments with the primary distinction between
thermal break embodiments and thermally resistive sleeve
embodiments being that the thermally resistive material is disposed
adjacent to sidewalls of the heat transfer fluid channel in
addition to being present between the heat transfer fluid channel
and the working surface. As further illustrated in FIG. 5A, the
thermally resistive sleeve 550 may further be disposed on a side of
the channel opposite the working surface to completely surround the
channel with the thermally resistive material. In other embodiments
however, the thermally resistive sleeve 550 is only present on 3
sides of the channel (e.g., as depicted in FIG. 5B illustrating a
cross-sectional view along the B-B' line of the temperature
controlled plasma processing chamber component 100 depicted in FIG.
1).
[0051] Thermally resistive channel sleeve embodiments may further
allow for a single channel level construction of the component
(e.g., embedded within layer 225). Many techniques known in the art
may be utilized to form the thermally resistive sleeve 550,
depending on the thermally resistive material chosen. For example,
a coating process may be selectively applied and/or selectively
removed to/from lengths of channels machined into the layer 225. In
other embodiments, large regions of layer 225 replaced with the
thermally resistive material is then machined to form channels
within the thermally resistive material. As further illustrated in
FIG. 5B, both the first and third lengths 112B and 114B of a heat
transfer fluid channel within the non-targeted temperature zone 105
are associated with larger thermal resistances R1, for example
because of a lower heat transfer coefficient attributable to the
resistive sleeves 550 along the heat transfer fluid channel lengths
112B and 114B.
[0052] In another embodiment, a heat transfer fluid channel length
has a first cross-sectional area larger than a second
cross-sectional area of a second length to modulate an extent of
convection occurring within the heat transfer fluid as it passes
through the fluid channel during operation. FIG. 6A illustrates a
cross-sectional view along the A-A' line of the temperature
controlled plasma processing chamber component 100 depicted in FIG.
1, in accordance with an embodiment of the present invention. In
the exemplary embodiment depicted, a cross-sectional area of along
the channel length 114B is sufficiently large to ensure laminar
flow of the heat transfer fluid along at least a portion of the
channel length 114B while the cross-sectional area along the
channel length 113B is sufficiently small to induce turbulent flow
of the heat transfer fluid along at least a portion of the channel
length 113B. In other embodiments where the heat transfer fluid
flow velocity within the channel length 114B and 113B are both in
the turbulent or laminar regime, different fluid velocities within
the lengths 114B and 113B nevertheless result in different heat
transfer coefficients h between the two lengths with higher
velocity providing higher heat transfer. It should also be
appreciated that the cross sectional area of the heat transfer
fluid channel may be so modulated in combination with the other
embodiments described herein (e.g., in FIGS. 2A-5B) modulation of
the heat transfer fluid flow velocity may be
[0053] For the depicted embodiment the channel cross-sectional area
is modulated by machining the capping layer 227 to have relief
where a larger cross-sectional area is to be (e.g., in non-targeted
temperature zones that overly the channel length 114B) and to have
a full capping layer thickness where a smaller cross-sectional area
is to be (e.g., in targeted temperatures zones that overly the
channel length 113B). FIG. 6B illustrates a cross-sectional view
along the B-B' line of the temperature controlled plasma processing
chamber component 100 depicted in FIG. 1, in accordance with an
embodiment of the present invention. As illustrated, both the first
and third lengths 112B and 114B of a heat transfer fluid channel
within the non-targeted temperature zone 105 are associated with
larger thermal resistances R1, for example because of a lower heat
transfer coefficient attributable to the reduced convection in
laminar/lower velocity flow regimes within in heat transfer fluid
channel lengths 112B and 114B. As further illustrated in FIGS. 6A
and 6B, modulation of the heat transfer area between lengths of a
heat transfer fluid channel may allow for a simplified assembly
including only the layer 225 and a single level of channels. It
should also be noted that larger cross-sectional areas may be
provided by increasing a lateral width of the channel.
[0054] FIGS. 7 and 8 illustrate a plasma etch system including a
temperature controlled component, in accordance with an embodiment
of the present invention. The plasma etch system 700 may be any
type of high performance etch chamber known in the art, such as,
but not limited to, Enabler.TM., MxP.RTM., MxP+.TM., Super-E.TM.,
DPS II AdvantEdge.TM. G3, or E-MAX.RTM. chambers manufactured by
Applied Materials of CA, USA. Other commercially available plasma
etch chambers may include similar temperature-controlled
components. While the exemplary embodiments are described in the
context of the plasma etch system 700, it should be further noted
that the temperature control system architecture described herein
is also adaptable to other plasma processing systems (e.g., plasma
deposition systems, etc.) which present a heat load on a
temperature-controlled component.
[0055] The plasma etch system 700 includes a grounded chamber 705.
A substrate 710 is loaded through an opening 715 and clamped to a
chuck 721. The substrate 710 may be any workpiece conventionally
employed in the plasma processing art and the present invention is
not limited in this respect. The plasma etch system 700 includes a
temperature-controlled process gas showerhead 735. In the exemplary
embodiment depicted, the process gas showerhead 735 includes a
plurality of zones 110 (center) and 105 (edge), each zone
independently controllable to a setpoint temperature. Other
embodiments have either more than two zones. For certain
embodiments with more than one zone, there are n heater zones and m
coolant zones where n need not be equal to m. For example, in the
embodiment depicted, a single cooling loop (m=1) passes through two
temperature zones (n=2). Process gases, are supplied from gas
source 745 through a mass flow controller 749, through the
showerhead 735 and into the interior of the chamber 705. Chamber
705 is evacuated via an exhaust valve 751 connected to a high
capacity vacuum pump stack 755.
[0056] When plasma power is applied to the chamber 705, a plasma is
formed in a processing region over substrate 710. A plasma bias
power 725 is coupled to the chuck 721 (e.g., cathode) to energize
the plasma. The plasma bias power 725 typically has a low frequency
between about 2 MHz to 60 MHz, and in a particular embodiment, is
in the 13.56 MHz band. In the exemplary embodiment, the plasma etch
system 700 includes a second plasma bias power 726 operating at
about the 2 MHz band which is connected to the same RF match 727 as
plasma bias power 725. A plasma source power 730 is coupled through
a match 731 to a plasma generating element to provide source power
to inductively or capacitively energize the plasma. The plasma
source power 730 typically has a higher frequency than the plasma
bias power 725, such as between 100 and 180 MHz, and in a
particular embodiment, is in the 162 MHz band.
[0057] The temperature controller 775 may be either software or
hardware or a combination of both software and hardware. The
temperature controller 775 is to output control signals affecting
the rate of heat transfer between the showerhead 735 and a heat
source and/or heat sink external to the plasma chamber 705 based on
at least temperature sensors 766 and 767. In the exemplary
embodiment, the temperature controller 775 is coupled, either
directly or indirectly, to the heat exchanger/chillers 777 and 782
(or heat exchanger/chillers 777 and a TE element, resistive heater,
etc.).
[0058] The heat exchanger/chiller 777 is to provide a cooling power
to the showerhead 735 via a heat transfer fluid loop 778 thermally
coupling the showerhead 735 with the heat exchanger/chiller 777. In
the exemplary embodiment, the heat transfer fluid loop 778 passes a
liquid (e.g., 50% ethylene glycol in DI water at a setpoint
temperature of -15.degree. C.) through a coolant channel embedded
in both the inner zone 110 and outer zone 105 (e.g., entering
proximate to a first zone and exiting proximate to the other zone)
of the showerhead 735 and may therefore incorporate any of the
embodiments described herein to differentiate the heat transfer of
the channel between the separate zones. The temperature controller
775 is coupled to a coolant liquid pulse width modulation (PWM)
driver 780. The coolant liquid PWM driver 780 may be of any type
commonly available and configurable to operate the valve(s) 720 for
embodiments where those valves are digital (i.e., having binary
states; either fully open or fully closed) at a duty cycle
dependent on control signals sent by the temperature controller
775. For example, the PWM signal can be produced by a digital
output port of a computer (e.g., controller 770) and that signal
can be used to drive a relay that controls the valves to on/off
positions.
[0059] In the embodiment depicted in FIG. 7, the system 700
includes the second heat exchanger/chiller 782 to provide a cooling
power to the showerhead 735 via a heat transfer fluid loop 779. In
the exemplary embodiment, the heat transfer fluid loop 779 is
employed which passes a cold liquid (e.g., 50% ethylene glycol in
DI water at a setpoint temperature of -15.degree. C.) through a
coolant channel embedded in only the outer zone 105 of the
showerhead 735. The temperature controller 775 is coupled to a
coolant liquid pulse width modulation (PWM) driver 781 to drive a
relay that controls the valves 720 to on/off positions, etc.
[0060] FIG. 8 illustrates a schematic of the plasma etch system 800
including a temperature controlled substrate supporting chuck, in
accordance with an embodiment of the present invention, and may be
combined with the showerhead embodiment depicted in FIG. 7 for a
plasma etch system including two temperature-controlled components.
As further depicted in FIG. 8, the chuck 721 includes an inner zone
110 and outer zone 105, each coupled to a separate heat source/sink
(heat exchanger/chillers 777, 778). As illustrated the heat
exchanger/chiller 777 is coupled to a heat transfer fluid channel
in the chuck 721 that passes only through the inner zone 110 while
the heat exchanger/chiller 778 is coupled to a heat transfer fluid
channel in the chuck 721 that passes through both the outer zone
105 and the inner zone 110 and may therefore incorporate any of the
embodiments described herein to differentiate the heat transfer of
the channel between the separate zones.
[0061] It is to be understood that the above description is
intended to be illustrative, and not restrictive. Many other
embodiments will be apparent to those of skill in the art upon
reading and understanding the above description. Although the
present invention has been described with reference to specific
exemplary embodiments, it will be recognized that the invention is
not limited to the embodiments described, but can be practiced with
modification and alteration within the spirit and scope of the
appended claims. Accordingly, the specification and drawings are to
be regarded in an illustrative sense rather than a restrictive
sense. The scope of the invention should, therefore, be determined
with reference to the appended claims, along with the full scope of
equivalents to which such claims are entitled.
* * * * *