U.S. patent application number 12/512520 was filed with the patent office on 2011-02-03 for light-up prevention in electrostatic chucks.
This patent application is currently assigned to c/o Lam Research Corporation. Invention is credited to Daniel Byun, Rajinder Dhindsa, Babak Kadkhodayan, Tom Stevenson, Saurabh Ullal.
Application Number | 20110024049 12/512520 |
Document ID | / |
Family ID | 43525875 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110024049 |
Kind Code |
A1 |
Stevenson; Tom ; et
al. |
February 3, 2011 |
LIGHT-UP PREVENTION IN ELECTROSTATIC CHUCKS
Abstract
An electrostatic chuck assembly is provided comprising a ceramic
contact layer, a patterned bonding layer, an electrically
conductive base plate, and a subterranean arc mitigation layer. The
ceramic contact layer and the electrically conductive base plate
cooperate to define a plurality of hybrid gas distribution channels
formed in a subterranean portion of the electrostatic chuck
assembly. Individual ones of the hybrid gas distribution channels
comprise surfaces of relatively high electrical conductivity
presented by the electrically conductive base plate and relatively
low electrical conductivity presented by the ceramic contact layer.
The subterranean arc mitigation layer comprises a layer of
relatively low electrical conductivity and is formed over the
relatively high conductivity surfaces of the hybrid gas
distribution channels in the subterranean portion of the
electrostatic chuck assembly. Semiconductor wafer processing
chambers are also provided.
Inventors: |
Stevenson; Tom; (Morgan
Hill, CA) ; Byun; Daniel; (Newark, CA) ;
Ullal; Saurabh; (Union City, CA) ; Kadkhodayan;
Babak; (Pleasanton, CA) ; Dhindsa; Rajinder;
(San Jose, CA) |
Correspondence
Address: |
Dinsmore & Shohl LLP;Fifth Third Center
One South Main Street, Suite 1300
Dayton
OH
45402-2023
US
|
Assignee: |
c/o Lam Research
Corporation
Fremont
CA
|
Family ID: |
43525875 |
Appl. No.: |
12/512520 |
Filed: |
July 30, 2009 |
Current U.S.
Class: |
156/345.53 |
Current CPC
Class: |
H01J 37/3255 20130101;
H01L 21/6875 20130101; H01L 21/6831 20130101; H01L 21/68757
20130101; H01J 37/32541 20130101; H01L 21/6833 20130101; H01L
21/67109 20130101 |
Class at
Publication: |
156/345.53 |
International
Class: |
C23F 1/00 20060101
C23F001/00 |
Claims
1. An electrostatic chuck assembly comprising a ceramic contact
layer, a patterned bonding layer, an electrically conductive base
plate, and a subterranean arc mitigation layer, wherein: the
patterned bonding layer is configured to secure the ceramic contact
layer to the electrically conductive base plate; the ceramic
contact layer and the electrically conductive base plate cooperate
to define a plurality of hybrid gas distribution channels formed in
a subterranean portion of the electrostatic chuck assembly; the
ceramic contact layer comprises a contact face and a plurality of
coolant ports formed in the contact face of the ceramic contact
layer; the coolant ports are in fluid communication with the hybrid
gas distribution channels of the electrostatic chuck assembly;
individual ones of the hybrid gas distribution channels comprise
surfaces of relatively high electrical conductivity presented by
the electrically conductive base plate and relatively low
electrical conductivity presented by the ceramic contact layer; and
the subterranean arc mitigation layer comprises a layer of
relatively low electrical conductivity and is formed over the
relatively high conductivity surfaces of the hybrid gas
distribution channels in the subterranean portion of the
electrostatic chuck assembly.
2. An electrostatic chuck assembly as claimed in claim 1 wherein
the subterranean arc mitigation layer comprises a dielectric layer
characterized by a thickness that is at least approximately 75
.mu.m but less than approximately 350 .mu.m.
3. An electrostatic chuck assembly as claimed in claim 1 wherein
the subterranean arc mitigation layer comprises a dielectric layer
characterized by a thickness that is less than approximately 35% of
a thickness of the ceramic contact layer.
4. An electrostatic chuck assembly as claimed in claim 1 wherein
the subterranean arc mitigation layer comprises a spray-on
dielectric coating.
5. An electrostatic chuck assembly as claimed in claim 1 wherein
the subterranean arc mitigation layer comprises a spray-on alumina
coating.
6. An electrostatic chuck assembly as claimed in claim 1 wherein
the subterranean arc mitigation layer comprises a spray-on alumina
dielectric layer characterized by a thickness less than
approximately 350 .mu.m.
7. An electrostatic chuck assembly as claimed in claim 1 wherein
the subterranean arc mitigation layer comprises a continuous or
discontinuous anodized layer or a layer of alumina, Yttria, YAG, or
combinations thereof.
8. An electrostatic chuck assembly as claimed in claim 1 wherein
the subterranean arc mitigation layer comprises a discontinuous
layer comprising portions of relatively low conductivity material
limited to the hybrid gas distribution channels or regions disposed
relatively adjacent thereto.
9. An electrostatic chuck assembly as claimed in claim 1 wherein
the hybrid gas distribution channels formed in the subterranean
portion of the electrostatic chuck assembly comprise counter-bored
grooves formed in a surface of the electrically conductive base
plate, a surface of the ceramic contact layer, or both.
10. An electrostatic chuck assembly as claimed in claim 1 wherein
gas distribution channel surfaces of relatively high electrical
conductivity are presented by counter-bored grooves formed in a
surface of the electrically conductive base plate.
11. An electrostatic chuck assembly as claimed in claim 10 wherein
gas distribution channel surfaces of relatively low electrical
conductivity are presented by a backside face of the ceramic
contact layer.
12. An electrostatic chuck assembly as claimed in claim 10 wherein
gas distribution channel surfaces of relatively low electrical
conductivity are presented by one or more sidewall faces of the
ceramic contact layer.
13. An electrostatic chuck assembly as claimed in claim 1 wherein
gas distribution channel surfaces of relatively low electrical
conductivity are presented by counter-bored grooves formed in the
ceramic contact layer.
14. An electrostatic chuck assembly as claimed in claim 13 wherein
gas distribution channel surfaces of relatively high electrical
conductivity are presented by a frontside face of the electrically
conductive base plate.
15. An electrostatic chuck assembly as claimed in claim 1 wherein
the ceramic contact layer comprises an alumina dielectric, an
alumina and titanium dioxide dielectric, aluminum nitride, silicon
nitride, silicon carbide, boron nitride, yttria, yttrium aluminate,
or any combination thereof, with or without trace impurities.
16. An electrostatic chuck assembly as claimed in claim 1 wherein
the patterned bonding layer comprises a pattern of voids aligned
with the hybrid gas distribution channels.
17. An electrostatic chuck assembly as claimed in claim 1 wherein
the patterned bonding layer comprises silicone.
18. An electrostatic chuck assembly as claimed in claim 1 wherein
the patterned bonding layer comprises an adhesive.
19. An electrostatic chuck assembly comprising a ceramic contact
layer, a silicone patterned bonding layer, an electrically
conductive base plate, and a subterranean arc mitigation layer,
wherein: the patterned bonding layer is configured to secure the
ceramic contact layer to the electrically conductive base plate;
the ceramic contact layer and the electrically conductive base
plate cooperate to define a plurality of hybrid gas distribution
channels formed in a subterranean portion of the electrostatic
chuck assembly; the hybrid gas distribution channels comprise
counter-bored grooves formed in a surface of the electrically
conductive base plate, a surface of the ceramic contact layer, or
both; the ceramic contact layer comprises a contact face and a
plurality of coolant ports formed in the contact face of the
ceramic contact layer; the coolant ports are in fluid communication
with the hybrid gas distribution channels of the electrostatic
chuck assembly; individual ones of the hybrid gas distribution
channels comprise surfaces of relatively high electrical
conductivity presented by the electrically conductive base plate
and relatively low electrical conductivity presented by the ceramic
contact layer; the subterranean arc mitigation layer comprises a
spray-on alumina dielectric layer characterized by a thickness less
than approximately 350 .mu.m formed over the relatively high
conductivity surfaces of the hybrid gas distribution channels in
the subterranean portion of the electrostatic chuck assembly.
20. A semiconductor wafer processing chamber comprising an
electrostatic chuck assembly, a processing chamber, a voltage
source, and a supply of coolant gas, wherein: the electrostatic
chuck assembly is positioned in the processing chamber and
comprises a ceramic contact layer, a patterned bonding layer, an
electrically conductive base plate, and a subterranean arc
mitigation layer; the voltage source is coupled electrically to the
electrically conductive base plate; the patterned bonding layer is
configured to secure the ceramic contact layer to the electrically
conductive base plate; the ceramic contact layer and the
electrically conductive base plate cooperate to define a plurality
of hybrid gas distribution channels formed in a subterranean
portion of the electrostatic chuck assembly; the supply of coolant
gas is coupled fluidly to the hybrid gas distribution channels; the
ceramic contact layer comprises a contact face and a plurality of
coolant ports formed in the contact face of the ceramic contact
layer; the coolant ports are in fluid communication with the hybrid
gas distribution channels of the electrostatic chuck assembly;
individual ones of the hybrid gas distribution channels comprise
surfaces of relatively high electrical conductivity presented by
the electrically conductive base plate and relatively low
electrical conductivity presented by the ceramic contact layer; and
the subterranean arc mitigation layer comprises a layer of
relatively low electrical conductivity and is formed over the
relatively high conductivity surfaces of the hybrid gas
distribution channels in the subterranean portion of the
electrostatic chuck assembly.
Description
BACKGROUND
[0001] The present disclosure relates to electrostatic chucks and,
more particularly, to an electrostatic chuck designs including
features that help prevent electrical arcing between the chuck
assembly and the wafer being processed or plasma ignition in
backside gas distribution channels.
BRIEF SUMMARY
[0002] Electrostatic chucks can be used to fix, clamp or otherwise
handle a silicon wafer for semiconductor processing. Many
electrostatic chucks are also configured to help regulate the
temperature of the wafer during processing. For example, as is well
documented in the art, a high thermal conductivity gas such as
helium gas can circulated in an electrostatic chuck to help
regulate the temperature of the wafer. More specifically, a
relatively thin layer of gas at relatively low pressure can be used
to sink heat from a silicon wafer during plasma-etch fabrication or
other semiconductor processing steps. The relatively low pressure
of the gas, which typically exerts only a few pounds of force on
the wafer, permits the use of electrostatic attraction to oppose it
and seal the wafer to a face of the chuck.
[0003] As will be appreciated by those practicing the present
invention, the concepts of the present disclosure are applicable to
a wide variety of electrostatic chuck configurations that would
otherwise be prone to plasma arcing and backside gas ionization
including, but not limited to, those illustrated in U.S. Pat. Nos.
5,583,736, 5,715,132, 5,729,423, 5,742,331, 6,422,775, 6,606,234,
and others. The concepts of the present disclosure have been
illustrated with reference to the relatively simple chuck
configurations of FIGS. 1 and 2 for clarity but the scope of the
present disclosure should not be limited to these relatively simple
configurations.
[0004] In accordance with one embodiment of the present disclosure,
an electrostatic chuck assembly is provided comprising a ceramic
contact layer, a patterned bonding layer, an electrically
conductive base plate, and a subterranean arc mitigation layer. The
ceramic contact layer and the electrically conductive base plate
cooperate to define a plurality of hybrid gas distribution channels
formed in a subterranean portion of the electrostatic chuck
assembly. Individual ones of the hybrid gas distribution channels
comprise surfaces of relatively high electrical conductivity
presented by the electrically conductive base plate and relatively
low electrical conductivity presented by the ceramic contact layer.
The subterranean arc mitigation layer comprises a layer of
relatively low electrical conductivity and is formed over the
relatively high conductivity surfaces of the hybrid gas
distribution channels in the subterranean portion of the
electrostatic chuck assembly.
[0005] In accordance with another embodiment of the present
disclosure, a semiconductor wafer processing chamber is provided
comprising an electrostatic chuck assembly having one or more of
the novel features disclosed herein.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0006] The following detailed description of specific embodiments
of the present disclosure can be best understood when read in
conjunction with the following drawings, where like structure is
indicated with like reference numerals and in which:
[0007] FIG. 1 is a schematic illustration of an electrostatic chuck
assembly according to embodiments of the present disclosure where
gas distribution channel surfaces are presented by counter-bored
grooves formed in a surface of an electrically conductive base
plate;
[0008] FIG. 2 is a schematic illustration of an electrostatic chuck
assembly according to embodiments of the present disclosure where
gas distribution channel surfaces are presented by counter-bored
grooves formed in a ceramic contact layer;
[0009] FIG. 3 is a schematic illustrations of an electrostatic
chuck assemblies where a subterranean arc mitigation layer is
limited to the hybrid gas distribution channels or regions disposed
relatively adjacent thereto; and
[0010] FIG. 4 is a schematic illustration of an electrostatic chuck
assembly according to embodiments of the present disclosure where
gas distribution channel surfaces of relatively low electrical
conductivity are presented by one or more sidewall faces of a
ceramic contact layer.
DETAILED DESCRIPTION
[0011] Referring initially to FIG. 1, an electrostatic chuck
assembly 10 is illustrated in the context of a non-specific
semiconductor wafer processing chamber 100 comprising a processing
chamber 60, a voltage source 70, and a supply of coolant gas 80.
The electrostatic chuck assembly 10 is positioned in the processing
chamber to secure a wafer 15 for processing and comprises a ceramic
contact layer 20, a patterned bonding layer 30, an electrically
conductive base plate 40, and a subterranean arc mitigation layer
50. The semiconductor wafer processing chamber 100 is described
herein as being non-specific because it is contemplated that the
concepts of the present disclosure will be applicable to a variety
of types of semiconductor wafer processing chambers and should not
be limited to chambers similar to that illustrated generally in
FIGS. 1-4.
[0012] The ceramic contact layer 20 and the electrically conductive
base plate 40 cooperate to define a plurality of hybrid gas
distribution channels 35 formed in a subterranean portion of the
electrostatic chuck assembly 10. The ceramic contact layer 20 also
comprises a plurality of coolant ports 22 formed in the contact
face 25 of the contact layer 20. For the purposes of describing and
defining the present invention, it is noted that "subterranean"
portions of the electrostatic chuck assembly 10 lie below the
contact face 25 of the ceramic contact layer 20, between the
contact face 25 and a distal portion 42 of the electrically
conductive base plate 40. For illustrative purposes, the wafer 15
is shown to be slightly displaced from the contact face 25 but in
operation, the wafer 15 will be electrostatically secured to the
contact face 25.
[0013] The patterned bonding layer 30 is configured to secure the
ceramic contact layer 20 to the electrically conductive base plate
40 and may comprise, for example, silicone, acrylic or a
conventional or yet to be developed adhesive suitable for use in
semiconductor wafer processing chambers. To prevent obstruction of
coolant flow in the hybrid gas distribution channels 35, the
patterned bonding layer 30 can be configured to comprise a pattern
of voids that are aligned with the hybrid gas distribution channels
35.
[0014] The coolant ports 22 are in fluid communication with the
hybrid gas distribution channels 35 of the electrostatic chuck
assembly 10 and the hybrid gas distribution channels 35 are coupled
fluidly to the coolant gas supply 80. As such, the thermally
conductive coolant gas can be directed from the coolant gas supply
80 to the coolant ports 22 via the hybrid gas distribution channels
35, which may be configured to communicate with a common coolant
inlet 24 and can be distributed across a coolant plane in the
subterranean portion of the electrostatic chuck assembly 10.
[0015] Each of the hybrid gas distribution channels 35 comprise
surfaces of relatively high and relatively low electrical
conductivity. Specifically, the highly conductive channel surfaces
are those presented by the electrically conductive base plate 40,
which is typically aluminum or another metal suitable for use in a
wafer processing chamber 100. The less conductive channel surfaces
are presented by the ceramic contact layer 20, which is typically a
ceramic dielectric like alumina, aluminum nitride or another
electrically insulating dielectric suitable for use in a wafer
processing chamber 100.
[0016] It is contemplated that the hybrid gas distribution channels
35 can be formed in the subterranean portion of the electrostatic
chuck assembly 10 by providing counter-bored grooves in a surface
of the electrically conductive base plate 40, a surface of the
ceramic contact layer 20, or both. For example, in FIG. 1, gas
distribution channel surfaces of relatively high electrical
conductivity are presented by forming counter-bored grooves in the
electrically conductive base plate 40. The counter-bored grooves in
the base plate 40 cooperate with low conductivity gas distribution
channel surfaces presented by the backside face 27 of the ceramic
contact layer 20 to collectively form each hybrid gas distribution
channel 35. In FIG. 2, gas distribution channel surfaces of
relatively low electrical conductivity are presented by forming
counter-bored grooves formed in the ceramic contact layer 20. The
counter-bored grooves in the ceramic contact layer 20 cooperate
with high conductivity gas distribution channel surfaces presented
by the frontside face 45 of the electrically conductive base plate
40. In FIG. 4, the coolant ports 22 are expanded in size and the
gas distribution channel surfaces of relatively low electrical
conductivity are presented by the sidewall faces 29 of the ceramic
contact layer 20.
[0017] Regardless of the manner in which the hybrid gas
distribution channels 35 are formed, the subterranean arc
mitigation layer 50, which comprises a layer of relatively low
electrical conductivity, should be formed over the relatively high
conductivity surfaces of the hybrid gas distribution channels 35 to
help mitigate destructive arcing that can occur when electric
fields in the gas distribution channels 35 reach a point where
plasma is ignited in the channels 35 or when process plasma works
its way into the channels 35 during wafer processing. In either
case, the gas distribution channels 35 can begin to "glow,"
creating a low impedance path for electrical arcing between the
conductive base plate 40 and the wafer 15. In the context of plasma
etch chambers utilizing He cooling gas, this phenomenon is
generally referred to as He hole light-up.
[0018] The subterranean arc mitigation layer 50, which may comprise
a spray-on coating of alumina or another dielectric, performs
optimally if it comprises a dielectric layer that characterized by
a thickness that is at least approximately 75 .mu.m but less than
approximately 350 .mu.m, although a variety of workable thicknesses
are contemplated outside of this range. Typically, the subterranean
arc mitigation layer 50 comprises a dielectric layer characterized
by a thickness that is less than approximately 35% of a thickness
of the ceramic contact layer 20. In addition to alumina, it is
contemplated that the subterranean arc mitigation layer 50 may
comprise a continuous or discontinuous anodized layer or a layer of
alumina, yttria, yttrium aluminum garnet, or combinations thereof.
It is also contemplated that the subterranean arc mitigation layer
50 may comprise a discontinuous layer that is limited to the hybrid
gas distribution channels or regions disposed relatively adjacent
thereto, as is illustrated in FIG. 3.
[0019] The ceramic contact layer 20, which typically comprises a
substantially planar contact face 25, may comprise any suitable
ceramic for use in a wafer processing chamber including, for
example, an alumina dielectric, an alumina and titanium dioxide
dielectric, aluminum nitride, silicon nitride, silicon carbide,
boron nitride, yttria, yttrium aluminate, or any combination
thereof, with or without trace impurities. It is contemplated that
the ceramic contact layer may further comprise a sintering aid, a
bonding agent, a corrosion resistant coating, a mechanically
conformal coating, or combinations thereof. Similarly, the
electrically conductive base plate may comprise any suitable
electrically conductive material for use in a wafer processing
chamber including, for example, an electrically conductive aluminum
pedestal of substantially uniform composition.
[0020] It is noted that recitations herein of a component of the
present disclosure being "configured" in a particular way, to
embody a particular property, or function in a particular manner,
are structural recitations, as opposed to recitations of intended
use. More specifically, the references herein to the manner in
which a component is "configured" denotes an existing physical
condition of the component and, as such, is to be taken as a
definite recitation of the structural characteristics of the
component.
[0021] It is noted that terms like "preferably," "commonly," and
"typically," when utilized herein, are not utilized to limit the
scope of the claimed invention or to imply that certain features
are critical, essential, or even important to the structure or
function of the claimed invention. Rather, these terms are merely
intended to identify particular aspects of an embodiment of the
present disclosure or to emphasize alternative or additional
features that may or may not be utilized in a particular embodiment
of the present disclosure.
[0022] For the purposes of describing and defining the present
invention it is noted that the terms "substantially" and
"approximately" are utilized herein to represent the inherent
degree of uncertainty that may be attributed to any quantitative
comparison, value, measurement, or other representation. The terms
"substantially" and "approximately" are also utilized herein to
represent the degree by which a quantitative representation may
vary from a stated reference without resulting in a change in the
basic function of the subject matter at issue.
[0023] Having described the subject matter of the present
disclosure in detail and by reference to specific embodiments
thereof, it will be apparent that modifications and variations are
possible without departing from the scope of the invention defined
in the appended claims. More specifically, although some aspects of
the present disclosure are identified herein as preferred or
particularly advantageous, it is contemplated that the present
disclosure is not necessarily limited to these aspects.
[0024] It is noted that one or more of the following claims utilize
the term "wherein" as a transitional phrase. For the purposes of
defining the present invention, it is noted that this term is
introduced in the claims as an open-ended transitional phrase that
is used to introduce a recitation of a series of characteristics of
the structure and should be interpreted in like manner as the more
commonly used open-ended preamble term "comprising."
* * * * *