U.S. patent application number 16/113736 was filed with the patent office on 2018-12-20 for multiple electrode substrate support assembly and phase control system.
The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to Kenneth S. COLLINS, Steven LANE, Roger Alan LINDLEY, Andrew NGUYEN, Kartik RAMASWAMY, Shahid RAUF, Lawrence WONG, Yang YANG.
Application Number | 20180366306 16/113736 |
Document ID | / |
Family ID | 57546264 |
Filed Date | 2018-12-20 |
United States Patent
Application |
20180366306 |
Kind Code |
A1 |
YANG; Yang ; et al. |
December 20, 2018 |
MULTIPLE ELECTRODE SUBSTRATE SUPPORT ASSEMBLY AND PHASE CONTROL
SYSTEM
Abstract
Implementations described herein provide a substrate support
assembly which enables tuning of a plasma within a plasma chamber.
In one embodiment, a method for tuning a plasma in a chamber is
provided. The method includes providing a first radio frequency
power and a direct current power to a first electrode in a
substrate support assembly, providing a second radio frequency
power to a second electrode in the substrate support assembly at a
different location than the first electrode, monitoring parameters
of the first and second radio frequency power, and adjusting one or
both of the first and second radio frequency power based on the
monitored parameters.
Inventors: |
YANG; Yang; (San Diego,
CA) ; RAMASWAMY; Kartik; (San Jose, CA) ;
LANE; Steven; (Porterville, CA) ; WONG; Lawrence;
(Fremont, CA) ; RAUF; Shahid; (Pleasanton, CA)
; NGUYEN; Andrew; (San Jose, CA) ; COLLINS;
Kenneth S.; (San Jose, CA) ; LINDLEY; Roger Alan;
(Santa Clara, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
57546264 |
Appl. No.: |
16/113736 |
Filed: |
August 27, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14742142 |
Jun 17, 2015 |
|
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16113736 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01J 37/3299 20130101;
H01J 37/32165 20130101; H01J 37/32568 20130101; H01J 37/32715
20130101 |
International
Class: |
H01J 37/32 20060101
H01J037/32 |
Claims
1. A substrate support assembly, comprising: a body having a
chucking electrode embedded therein, the chucking electrode
comprising a first electrode disposed adjacent to a substrate
support surface of the body; a second electrode disposed in the
substrate support assembly at a location further from the support
surface; and a power application system coupled to the substrate
support assembly, wherein the power application system comprises: a
radio frequency power source coupled to one or both of the first
and second electrodes through a matching network; and a sensor
coupled between the matching circuit and the first and second
electrodes.
2. The support assembly of claim 1, wherein the second electrode
includes a surface area that is greater than a surface area of the
first electrode.
3. The support assembly of claim 1, wherein the second electrode
includes a diameter that is greater than a diameter of the first
electrode.
4. The support assembly of claim 1, wherein the power application
system includes a first radio frequency power source coupled to the
first electrode and a second radio frequency power source coupled
to the second electrode.
5. The support assembly of claim 1, wherein the power application
system comprises a single radio frequency power source coupled to
both of the first electrode and the second electrode.
6. The support assembly of claim 5, further comprising a power
splitter coupled between the radio frequency power source and both
of the first electrode and the second electrode.
7. The support assembly of claim 1, wherein the body comprises a
dielectric material.
8. The support assembly of claim 1, wherein first electrode has a
diameter that is substantially equal to a diameter of a
substrate.
9. The support assembly of claim 1, further comprising a phase
shifter coupled to one or both of the first electrode and the
second electrode.
10. A substrate support assembly, comprising: a dielectric body
having a chucking electrode embedded therein, the chucking
electrode comprising a first electrode adapted to form a plasma
that is positioned adjacent to a substrate support surface of the
body; a second electrode disposed in the dielectric body at a
location further from the support surface; and a power application
system coupled to the substrate support assembly, wherein the power
application system comprises: a radio frequency power source
coupled to one or both of the first and second electrodes through a
matching network; and a sensor coupled between the matching circuit
and the first and second electrodes.
11. The support assembly of claim 10, wherein the second electrode
includes a surface area that is greater than a surface area of the
first electrode.
12. The support assembly of claim 10, wherein the second electrode
includes a diameter that is greater than a diameter of the first
electrode.
13. The support assembly of claim 10, wherein the power application
system includes a first radio frequency power source coupled to the
first electrode and a second radio frequency power source coupled
to the second electrode.
14. The support assembly of claim 10, wherein the power application
system comprises a single radio frequency power source coupled to
both of the first electrode and the second electrode.
15. The support assembly of claim 14, further comprising a power
splitter coupled between the radio frequency power source and both
of the first electrode and the second electrode.
16. The support assembly of claim 10, wherein the body comprises a
dielectric material.
17. The support assembly of claim 10, wherein first electrode has a
diameter that is substantially equal to a diameter of a
substrate.
18. The support assembly of claim 10, further comprising a phase
shifter coupled to one or both of the first electrode and the
second electrode.
19. A substrate support assembly, comprising: a dielectric body
having a chucking electrode embedded therein, the chucking
electrode comprising a first electrode adapted to form a plasma
that is positioned adjacent to a substrate support surface of the
body, wherein first electrode has a diameter that is substantially
equal to a diameter of a substrate; a second electrode embedded in
the dielectric body at a location further from the support surface,
wherein the second electrode includes a surface area that is
greater than a surface area of the first electrode; and a power
application system coupled to the substrate support assembly,
wherein the power application system comprises: a radio frequency
power source coupled to one or both of the first and second
electrodes through a matching network; and a sensor coupled between
the matching circuit and the first and second electrodes.
20. The support assembly of claim 19, wherein the power application
system comprises a single radio frequency power source coupled to
both of the first electrode and the second electrode.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/742,142, filed Jun. 17, 2015, which application is
incorporated by reference herein.
BACKGROUND
Field
[0002] Embodiments disclosed herein generally relate to
semiconductor manufacturing and more particularly to a substrate
support assembly and method of using the same.
Description of the Related Art
[0003] As the feature size of the device patterns get smaller, the
critical dimension (CD) requirements of these features become a
more important criterion for stable and repeatable device
performance. Allowable CD variation across a substrate processed
within a processing chamber is difficult to achieve due to chamber
asymmetries such as chamber and substrate temperature, flow
conductance, and RF fields.
[0004] In the current semiconductor manufacturing industry,
transistor structures have become increasingly complicated and
challenging with the development of the FinFet technology, for
example. On the substrate processing level, there is a need for
advancements in process uniformity control to allow fine, localized
process tuning as well as global processing tuning across the whole
substrate. As the transistor density across a substrate increases
according to the square of the radius, there is a demand for the
capability to control the process at the substrate edge, where the
electromagnetic field and plasma density and chemistry change due
to the existence of multiple material interfaces and/or multiple
geometric shapes.
[0005] Thus, there is a need for an improved substrate support
assembly that provides aspects that improve process tuning.
SUMMARY
[0006] Implementations disclosed herein provide methods and
apparatus which enables tuning of a plasma within a plasma chamber.
In one embodiment, a method for tuning a plasma in a chamber is
provided. The method includes providing a first radio frequency
power and a direct current power to a first electrode adjacent to a
substrate support surface of a substrate support assembly,
providing a second radio frequency power to a second electrode in
the substrate support assembly at a location further from the
support surface, monitoring parameters of the first and second
radio frequency power, and adjusting one or both of the first and
second radio frequency power based on the monitored parameters.
[0007] In another embodiment, a method for tuning a plasma in a
chamber is provided. The method includes providing a first radio
frequency power and a direct current power to a first electrode
adjacent to a substrate support surface of a substrate support
assembly, providing a second radio frequency power to a second
electrode in the substrate support assembly at a location further
from the support surface, monitoring parameters of the first and
second radio frequency power, and shifting a phase of one or both
of the first and second radio frequency power based on the
monitored parameters.
[0008] In another embodiment, a substrate support assembly is
provided. The substrate support assembly includes a body having a
chucking electrode embedded therein, the chucking electrode
including a first radio frequency electrode disposed adjacent to a
substrate support surface of the body. The body also includes a
second radio frequency electrode disposed in the substrate support
assembly at a location further from the support surface. The
substrate support assembly also includes a power application system
coupled to the substrate support assembly. The power application
system includes a radio frequency power source coupled to one or
both of the first and second radio frequency electrodes through a
matching network, and a sensor coupled between the matching circuit
and the first and second radio frequency electrodes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] So that the manner in which the above recited features of
the present disclosure can be understood in detail, a more
particular description of the disclosure, briefly summarized above,
may be had by reference to embodiments disclosed herein, some of
which are illustrated in the appended drawings. It is to be noted,
however, that the appended drawings illustrate only typical
implementations of this disclosure and are therefore not to be
considered limiting of its scope, for the disclosure may admit to
other equally effective implementations.
[0010] FIG. 1 is a cross-sectional schematic view of an exemplary
etch processing chamber having one embodiment of a substrate
support assembly.
[0011] FIG. 2 is a partial schematic cross-sectional view of
another embodiment of a processing chamber with another embodiment
of a substrate support assembly and a power application system.
[0012] FIG. 3 is a partial schematic cross-sectional view of
another embodiment of a processing chamber with another embodiment
of a substrate support assembly and a power application system.
[0013] FIG. 4 is an exemplary phase diagram showing a first
waveform and a second waveform according to one embodiment.
[0014] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one implementation may be beneficially used in other
implementations without specific recitation.
DETAILED DESCRIPTION
[0015] Embodiments disclosed herein provide a substrate support
assembly and a power application system which enables tuning of a
plasma in a processing chamber. The substrate support assembly may
include multiple electrodes which are coupled to a power
application system enables phase control of the plasma in the
chamber. The phase control may be used to manipulate plasma
uniformity and/or plasma distribution within the chamber. The
controlled plasma distribution may be utilized to tune plasma
density radially across a substrate. For example, the plasma may be
tuned to have a profile with a greater density at the edge of the
substrate relative a density at the center of the substrate, and
vice versa. Although the substrate support assembly and power
application system is described below in an etch processing
chamber, the substrate support assembly and power application
system may be utilized in other types of plasma processing
chambers, such as physical vapor deposition chambers, chemical
vapor deposition chambers, ion implantation chambers, stripping
chambers, among others, as well as other plasma systems where
tuning of a plasma profile is desirable.
[0016] FIG. 1 is a cross-sectional schematic view of an exemplary
etch processing chamber 100 having a substrate support assembly
101. As discussed above, the substrate support assembly 101 may be
utilized in other processing chambers, for example plasma treatment
chambers, chemical vapor deposition chambers, ion implantation
chambers, stripping chambers, among others, as well as other
systems where the ability to control a plasma profile at a surface
of a substrate, is desirable.
[0017] The processing chamber 100 includes a grounded chamber body
102. The chamber body 102 includes walls 104, a bottom 106 and a
lid 108 which enclose an internal volume 124. The substrate support
assembly 101 is disposed in the internal volume 124 and supports a
substrate 134 thereon during processing. The walls 104 of the
processing chamber 100 include an opening (not shown) through which
the substrate 134 may be robotically transferred into and out of
the internal volume 124. A pumping port 110 is formed in one of the
walls 104 or the bottom 106 of the chamber body 102, and is fluidly
connected to a pumping system (not shown). The pumping system is
utilized to maintain a vacuum environment within the internal
volume 124 of the processing chamber 100, while removing processing
byproducts.
[0018] A gas panel 112 provides process and/or other gases to the
internal volume 124 of the processing chamber 100 through one or
more inlet ports 114 formed through at least one of the lid 108 or
walls 104 of the chamber body 102. The process gas provided by the
gas panel 112 is energized within the internal volume 124 to form a
plasma 122. The plasma 122 is utilized to process the substrate 134
disposed on the substrate support assembly 101. The process gases
may be energized by RF power inductively coupled to the process
gases from a plasma applicator 120 positioned outside the chamber
body 102. In the exemplary embodiment depicted in FIG. 1, the
plasma applicator 120 is a pair of coaxial coils coupled through a
matching circuit 118 to an RF power source 116. In other
embodiments (not shown), the plasma applicator may be an electrode,
such as a showerhead, that may be used in a capacitively coupled
plasma system. The plasma 122 may also be formed utilizing other
techniques.
[0019] The substrate support assembly 101 generally includes at
least a substrate support 132. The substrate support 132 may be a
vacuum chuck, an electrostatic chuck, a susceptor, or other
substrate support surface. In the embodiment of FIG. 1, the
substrate support 132 is an electrostatic chuck and will be
described hereinafter as an electrostatic chuck 126.
[0020] The substrate support assembly 101 may additionally include
a heater assembly 170. The substrate support assembly 101 may also
include a cooling base 130. The cooling base 130 may alternately be
separate from the substrate support assembly 101. The substrate
support assembly 101 may be removably coupled to a support pedestal
125. The support pedestal 125, which may include a pedestal base
128 and a facility plate 180, is mounted to the chamber body 102.
The pedestal base 128 may comprise a dielectric material that
electrically insulates electrically conductive portions of the
substrate support assembly 101 from the chamber body 102. The
substrate support assembly 101 may be periodically removed from the
support pedestal 125 to allow for refurbishment of one or more
components of the substrate support assembly 101.
[0021] The substrate support assembly 101 includes a chucking
electrode 136, which may be a mesh of a conductive material. The
electrostatic chuck 126 has a mounting surface 131 and a substrate
support surface 133 opposite the mounting surface 131. The chucking
electrode 136 is coupled to a chucking power source 138 that, when
energized, electrostatically clamps the substrate 134 to the
workpiece support surface 133. The electrostatic chuck 126
generally includes the chucking electrode 136 embedded in a
dielectric puck or body 150. The dielectric body 150, as well as
other portions of the substrate support assembly 101 and the
support pedestal 125, may be disposed within an insulator ring 143.
The insulator ring 143 may be a dielectric material, such as quartz
or other dielectric material that is process compatible. A focus
ring 145 may be disposed about a periphery of the dielectric body
150. The focus ring 145 may be a dielectric or conductive material
and may comprise the same material as the substrate 134. The focus
ring 145 may be utilized to extend the surface of the substrate 134
with respect to the electromagnetic field of the plasma 122. The
focus ring 145 may also minimize the enhancement of electromagnetic
field at the edge of the substrate 134, as well as minimize the
chemistry effects due to the change in materials at this
interface.
[0022] The chucking electrode 136 may be configured as a mono polar
or bipolar electrode, or have another suitable arrangement. The
chucking electrode 136 is coupled through an RF filter 182 to a
chucking power source 138 which provides direct current (DC) power
to electrostatically secure the substrate 134 to the upper surface
of the dielectric body 150. The RF filter 182 prevents RF power
utilized to form the plasma 122 within the processing chamber 100
from damaging electrical equipment or presenting an electrical
hazard outside the chamber. The dielectric body 150 may be
fabricated from a ceramic material, such as AlN or Al.sub.2O.sub.3.
Alternately, the dielectric body 150 may be fabricated from a
polymer, such as polyimide, polyetheretherketone,
polyaryletherketone and the like.
[0023] The cooling base 130 is used to control the temperature of
the substrate support assembly 101. The cooling base 130 may be
coupled to a heat transfer fluid source 144. The heat transfer
fluid source 144 provides a heat transfer fluid, such as a liquid,
gas or combination thereof, which is circulated through one or more
conduits 160 disposed in the cooling base 130. The fluid flowing
through neighboring conduits 160 may be isolated to enabling local
control of the heat transfer between the electrostatic chuck 126
and different regions of the cooling base 130, which assists in
controlling the lateral temperature profile of the substrate 134.
The substrate support assembly 101 may also include the heater
assembly 170 that includes one or more resistive heaters (not
shown) encapsulated therein. The heater assembly 170 is coupled to
a heater power source 156 that may be used to control power to the
resistive heaters. The heater power source 156 may be coupled
through an RF filter 184. The RF filter 184 may be used to protect
the heater power source 156 from the RF energy. The electrostatic
chuck 126 may include one or more temperature sensors (not shown)
for providing temperature feedback information to the controller
148 for controlling the power applied by the heater power source
156 and for controlling the operations of the cooling base 130.
[0024] The substrate support surface 133 of the electrostatic chuck
126 may include gas passages (not shown) for providing backside
heat transfer gas to the interstitial space defined between the
substrate 134 and the substrate surface 133 of the electrostatic
chuck 126. The electrostatic chuck 126 may also include lift pin
holes for accommodating lift pins (both not shown) for elevating
the substrate 134 above the substrate support surface 133 of the
electrostatic chuck 126 to facilitate robotic transfer into and out
of the processing chamber 100.
[0025] A power application system 135 is coupled to the substrate
support assembly 101. The power application system 135 may include
the chucking power source 138, a first radio frequency (RF) power
source 142, and a second RF power source 178. Embodiments of the
power application system 135 may additionally include a controller
148, and a sensor device 181 that is in communication with the
controller 148 and both of the first RF power source 142 and the
second RF power source 178.
[0026] The controller 148 may be one of any form of general-purpose
data processing system that can be used in an industrial setting
for controlling the various subprocessors and subcontrollers.
Generally, the controller 148 includes a central processing unit
(CPU) 172 in communication with memory 174 and input/output (I/O)
circuitry 176, among other common components. Software commands
executed by the CPU of the controller 148, cause the processing
chamber to, for example, introduce an etchant gas mixture (i.e.,
processing gas) into the internal volume 124. The controller 148
may also be utilized to control the plasma 122 from the processing
gas by application of RF power from the plasma applicator 120, the
first RF power source 142 and the second RF power source 178 in
order to etch a layer of material on the substrate 134.
[0027] As described above, the substrate support assembly 101
includes the chucking electrode 136 that may function in one aspect
to chuck the substrate 134 while also functioning as a first RF
electrode. The heater assembly 170 may also include a second RF
electrode 154, and together with the chucking electrode 136,
applies RE power to tune the plasma 122. The first RF power source
142 may be coupled to the second RF electrode 154 while the second
RF power source 178 may be coupled to the chucking electrode 136. A
first matching network 151 and a second matching network 152 may be
provided for the first RF power source 142 and the second RF power
source 178, respectively. The second RF electrode 154 may be a
solid metal plate of a conductive material as shown. Alternatively,
the second RF electrode 154 may be a mesh of conductive
material.
[0028] The first RF power source 142 and the second RF power source
178 may produce power at the same frequency or a different
frequency. In some embodiments, one or both of the first RF power
source 142 and the second RF power source 178 may produce power at
a frequency of 13.56 megahertz (MHz) or a frequency of 2 MHz. In
other embodiments, the first RF power source 142 may produce power
at a frequency of 13.56 MHz and the second RF power source 178 may
produce power at a frequency of 2 MHz, or vice versa. RF power from
one or both of the first RF power source 142 and second RF power
source 178 may be varied in order to tune the plasma 122. For
example, the sensor device 181 may be used to monitor the RF energy
from one or both of the first RF power source 142 and the second RF
power source 178. Data from the sensor device 181 may be
communicated to the controller 148, and the controller 148 may be
utilized to vary power applied by the first RF power source 142 and
the second RF power source 178. In one embodiment, phase angle of
one or both of the first RF power source 142 and the second RF
power source 178 is monitored and adjusted in order to tune the
plasma 122.
[0029] By changing the phase angle, the plasma uniformity can be
tuned. Changing the phase angle will change the voltage/current
distribution across the chucking electrode 136 and the second RF
electrode 154. Varying the phase angle may also tune the spatial
distribution of the plasma across the substrate 134. For example,
the phase angle can be utilized to fine tune the process, whether
etch rate is center fast, or edge fast, or flat. Adjusting the
phase angle may also impact on the sheath dynamics which directly
affects processing results. As the chucking electrode 136 is closer
to the plasma 122 and the surface of the substrate 134 as compared
to the second RF electrode 154, control of the plasma according to
this aspect may be extremely effective. In some embodiments, the
power application system 135 provides three modes of control
including controlling RF power (e.g., frequency and/or wattage) to
the chucking electrode 136, controlling RF power (e.g., frequency
and/or wattage) to the second RF electrode 154, and control of the
phase between the chucking electrode 136 and the second RF
electrode 154. This control scheme provides greater process tuning
ability and/or the capability for effective edge control. The
increased edge control may be due to the size difference of the two
concentric electrodes and/or phase control of the RF power applied
thereto.
[0030] In some embodiments, the surface area of the second RF
electrode 154 may be greater than a surface area of the chucking
electrode 136. For example, the chucking electrode 136 may include
a first dimension or diameter while the second RF electrode 154 has
a second dimension or diameter that is greater than the first
diameter. In one embodiment, the chucking electrode 136 has a first
diameter that is substantially equal to a diameter of the substrate
134. The second RF electrode 154 may include a second diameter that
is greater than the first diameter. In one embodiment, the second
RF electrode 154 may have a surface area that is about 50% greater
than a surface area of the chucking electrode 136. In other
embodiments, the second RF electrode 154 may have a surface area
that is about 70% to about 80% greater than a surface area of the
chucking electrode 136. In one or more embodiments, the difference
in surface area may be utilized to control the process rate at
different locations of the substrate 134. For example, if power
delivered to the second RF electrode 154 is increased, the
processing rate of the edge of the substrate 134 increases. If
power delivered to the chucking electrode 136 is increased, then
the central area of the substrate 134 may be etched at a faster
rate with little impact on the edge of the substrate 134.
Therefore, a differential control for discrete regions on the
entire substrate 134 is achieved.
[0031] FIG. 2 is a partial schematic cross-sectional view of
another embodiment of a processing chamber 200 having a substrate
support assembly 101 and a power application system 205. Only a
lower portion of the processing chamber 200 is shown as the
substrate support assembly 101 and the power application system 205
may be utilized in many types of processing chambers. For example,
the upper portion of the processing chamber 200 may be configured
with hardware for plasma etching, chemical vapor deposition, ion
implantation, stripping, physical vapor deposition, plasma
annealing, and plasma treatment, among others.
[0032] The processing chamber 200 includes the substrate support
assembly 101 having the second RF electrode 154 coupled to the
first RF power source 142 through matching network 151. The
chucking electrode 136 is coupled to the second RF power source 178
through matching network 152. The first RF power source 142, the
first matching network 151 and the second RF electrode 154 may
comprise a first RF system 210 of the power application system 205.
Similarly, the second RF power source 178, the second matching
network 152 and the chucking electrode 136 may comprise a second RF
system 215 of the power application system 205.
[0033] The power application system 205 includes the sensor device
181 that in one embodiment includes a first sensor 220 and a second
sensor 225. Each of the first sensor 220 and the second sensor 225
may be voltage and current sensors (e.g., V/I sensors). Thus, the
voltage and current of each of the first RF system 210 and the
second RF system 215 may be monitored and tuned according to
embodiments described herein. Signals from each of the first sensor
220 and the second sensor 225 may be transmitted to the controller
148 and power applied to each of the first RF system 210 and the
second RF system 215 may be varied and tuned to control
distribution and/or density of plasma within the processing chamber
200.
[0034] FIG. 3 is a partial schematic cross-sectional view of
another embodiment of a processing chamber 300 having a substrate
support assembly 101 and a power application system 305. Only a
lower portion of the processing chamber 300 is shown as the
substrate support assembly 101 and the power application system 305
may be utilized with other processing chambers. For example, the
upper portion of the processing chamber 200 may be configured with
hardware for plasma etching, chemical vapor deposition, ion
implantation, stripping, physical vapor deposition, plasma
annealing, and plasma treatment, among others.
[0035] The processing chamber 300 includes the substrate support
assembly 101 having the chucking electrode 136 coupled to the first
RF power source 142. However, in this embodiment, a second RF
electrode 310 is also coupled to the first RF power source 142. The
second RF electrode 310 may be disposed in a ceramic plate 315
positioned between the cooling base 130 and the dielectric body 150
of the electrostatic chuck 126. The second RF electrode 310 may be
separated from the chucking electrode 136 by a metallic ground
plate 320. The metallic ground plate 320 may be positioned between
the ceramic plate 315 and the dielectric body 150. The metallic
ground plate 320 is utilized to electromagnetically isolate the
second RF electrode 310 from the chucking electrode 136. The second
RF electrode 310 may be a conductive mesh 325. Alternatively, the
second RF electrode 310 may be a solid plate made of a conductive
material. The metallic ground plate 320 may be an aluminum plate
that is coupled to ground potential.
[0036] The first RF power source 142 is operably coupled to both of
the chucking electrode 136 and the second RF electrode 310. A
single matching network 330 is disposed between the first RF power
source 142 and each of the chucking electrode 136 and the second RF
electrode 310. Thus, a first RF system 335 and a second RF system
340 are provided, and the chucking electrode 136 and the second RF
electrode 310 of each system share the first RF power source 142
and the matching network 330. The sensor device 181 includes the
first sensor 220 and the second sensor 225 as in other embodiments,
but the sensor device 181 may be optional or utilized only for
initial and/or periodic calibration. One or both of a controller
345 and a phase shifter 350 may also be included in each of the
first RF system 335 and the second RF system 340. For example, the
phase shifter 350 may be utilized to control phase angle based on
feedback from the sensor device 181, which may negate a need for
the controller 345 being utilized to control operation of the power
application system 305.
[0037] In some embodiments, the matching network 330 may be
utilized as a power splitter that varies power from the first RF
power source 142 to each of the chucking electrode 136 and the
second RF electrode 310. Utilizing one RF generator together with a
power splitting circuit 360 and a phase control/delay circuit
(e.g., phase shifter 350) to implement multiple electrode driving
may reduce costs of ownership. In other embodiments, the circuit of
matching network 330 serves two functions. A first function may be
impedance matching while the second function may be power splitting
between the chucking electrode 136 and the second RF electrode 310.
The manner of power splitting may be controllable through a
variable impedance circuit 355 coupled to either the chucking
electrode 136 or the second RF electrode 310. The variable
impedance circuit 355 may be utilized to vary the relative
impedances the chucking electrode 136 and the second RF electrode
310. In some embodiments, varying the relative impedances the
chucking electrode 136 and the second RF electrode 310 changes the
power distribution between the chucking electrode 136 and the
second RF electrode 310. Changing the power distribution between
the second RF electrode 310 and the chucking electrode 136 may be
utilized to tune the plasma.
[0038] In some embodiments, the phases of the RF signals from the
first RF power source 142 after splitting and matching are sensed
by the first sensor 220 and the second sensor 225. The signals may
be transmitted to the controller 345. The controller 345 may be
utilized to control the phase shifter 350 to control the phase
difference between the chucking electrode 136 and the second RF
electrode 310. The phase shifter 345 may be a phase delay circuit
or a more advanced device such as high RF power vector modulator.
The two RF hot electrodes, the chucking electrode 136 and the
second RF electrode 310, are electrically separated from each other
in this embodiment. Decoupling of the chucking electrode 136 or the
second RF electrode 310 can produce easier phase and/or power
control since the crosstalk between multiple RF generators is
decreased. Decoupling may also provide more sensitive and/or
effective edge tuning. The improved edge tuning may be due to the
relative sizes of the second RF electrode 310 and the chucking
electrode 136 as the larger electrode may have a lesser impact on
the center area of the substrate 134. Additionally, the decoupling
may also increase the phase angle operating regime. Further, if the
whole system is fabricated according to the same standard, the
first sensor 220 and the second sensor 225 may not be necessary for
the chamber after initial calibration.
[0039] FIG. 4 is an exemplary phase diagram 400 showing a first
waveform 405 and a second waveform 410. The first waveform 405 may
be indicative of the RE signal from the first RF system 210 (FIG.
2) or 335 (FIG. 3), and the second waveform 410 may be indicative
of the RF signal from the second RF system 215 (FIG. 2) or 340
(FIG. 3). The first waveform 405 and the second waveform 410 may be
measured by the first sensor 220 and the second sensor 225 (FIGS. 2
or 3) downstream of a matching network. While the first waveform
405 and the second waveform 410 are shown as having the same
frequency and amplitude in this example, the first waveform 405 and
the second waveform 410 may have a different frequency and/or
amplitude.
[0040] The phase difference .theta. between the first waveform 405
and the second waveform 410 may be varied as desired based on the
desired characteristics of a plasma. The phase angle may be varied
between about 0 degrees to about 360 degrees. The first waveform
405 and the second waveform 410 may be constructive or destructive
based on the desired characteristics of a plasma.
[0041] Control of the RF phase difference and/or phase angle
provides a powerful knob for fine process tuning. For example,
control of the RF phase difference and/or phase angle may be
utilized to control one or more of average etch rate, etch rate
uniformity, etch rate skew, critical dimension (CD) uniformity, CD
skew, CD range, and plasma uniformity and/or plasma density.
[0042] While the foregoing is directed to implementations of the
present disclosure, other and further implementations of the
disclosure may be devised without departing from the basic scope
thereof, and the scope thereof is determined by the claims that
follow.
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