U.S. patent application number 13/492531 was filed with the patent office on 2012-09-27 for rf power delivery system in a semiconductor apparatus.
Invention is credited to Zhigang Chen, Kartik Ramaswamy, Shahld Rauf.
Application Number | 20120241091 13/492531 |
Document ID | / |
Family ID | 41445204 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120241091 |
Kind Code |
A1 |
Chen; Zhigang ; et
al. |
September 27, 2012 |
RF POWER DELIVERY SYSTEM IN A SEMICONDUCTOR APPARATUS
Abstract
Embodiments of the invention provide an apparatus which provide
good RF uniformity within a processing chamber. In one embodiment,
an apparatus includes a substrate support assembly, a terminal, and
a dielectric insulator. The substrate support assembly has a center
passage formed along a center axis. An RF transmission line is
provided. The RF transmission line has a substantially vertical
portion and a substantially horizontal portion, wherein the
terminal is coupled to the substantially horizontal portion of the
RF transmission line. The dielectric insulator circumscribes the
substantially horizontal portion of the RF transmission line. The
dielectric insulator has a first opening through which the terminal
passes.
Inventors: |
Chen; Zhigang; (San Jose,
CA) ; Rauf; Shahld; (Pleasanton, CA) ;
Ramaswamy; Kartik; (San Jose, CA) |
Family ID: |
41445204 |
Appl. No.: |
13/492531 |
Filed: |
June 8, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12146189 |
Jun 25, 2008 |
8206552 |
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13492531 |
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Current U.S.
Class: |
156/345.43 |
Current CPC
Class: |
H01J 37/32706 20130101;
H01J 37/32091 20130101 |
Class at
Publication: |
156/345.43 |
International
Class: |
H01L 21/465 20060101
H01L021/465 |
Claims
1. A substrate support assembly, comprising: a substrate support
assembly; an RF transmission line coupled to a bottom of the
substrate support assembly at a region offset to a center axis of
the substrate support assembly; and a metal plate coupled to the RF
transmission line, wherein the metal plate comprises: a plurality
of conduits disposed in the metal plate.
2. The substrate support assembly of claim 1, wherein the conduits
of the metal plate are disposed within the substrate support
assembly.
3. The substrate support assembly of claim 1, wherein the conduits
have a top end coupled to an RF electrode of the substrate support
assembly.
4. The substrate support assembly of claim 3, wherein the substrate
support assembly further comprises: a base plate coupled to an
electrostatic chuck.
5. The substrate support assembly of claim 3, wherein the RF
electrode is embedded in the electrostatic chuck.
6. The substrate support assembly of claim 1, further comprising: a
dielectric insulating ring coupled to a bottom of the substrate
support assembly.
7. The substrate support assembly of claim 6, wherein the RF
transmission line is circumscribed by the dielectric insulating
ring.
8. The substrate support assembly of claim 6, wherein the metal
plate is disposed in the dielectric insulating ring.
9. The substrate support assembly of claim 1, wherein the conduits
are formed substantially perpendicular to the metal plate.
10. The substrate support assembly of claim 1, wherein the conduits
protrudes from the metal plate extending to the substrate support
assembly.
11. The substrate support assembly of claim 1, wherein the metal
plate is fabricated from a group consisting of copper, aluminum,
stainless steel and combinations thereof.
12. The substrate support assembly of claim 1, wherein the conduits
are distributed in a symmetrical manner utilizing an axis passing
through the region where the RF transmission line is attached to as
a center axis.
13. The substrate support assembly of claim 1, the location of the
conduits is adjustable.
14. The substrate support assembly of claim 6, wherein the
dielectric insulating ring is fabricated from a plastic material
selected from at least one of plastic, polymer or fluorocarbon.
15. A substrate support assembly, comprising: a substrate support
assembly; an RF transmission line coupled to a bottom of the
substrate support assembly at a region offset to a center axis of
the substrate support assembly; and a metal plate coupled to the RF
transmission line; and a plurality of conduits disposed in the
metal plate, wherein the conduits disposed in the metal plate are
distributed in a symmetrical manner utilizing an axis passing
through the region where the RF transmission line is attached to as
a center axis.
16. The substrate support assembly of claim 15, further comprising:
a dielectric insulating ring coupled to a bottom of the substrate
support assembly.
17. The substrate support assembly of claim 16, wherein the RF
transmission line is circumscribed by the dielectric insulating
ring.
18. The substrate support assembly of claim 15, wherein the
conduits have a top end coupled to an RF electrode of the substrate
support assembly.
19. The substrate support assembly of claim 15, the location of the
conduits is adjustable.
Description
CROSS-REFERENCE TO OTHER APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 12/146,189, entitled "RF POWER Jun. 25,
2008,(Attorney Docket No. APPM/13017) which is herein incorporated
by reference.
BACKGROUND
[0002] 1.Field
[0003] Embodiments of the invention generally relate to an RF
delivery system in a semiconductor substrate processing apparatus
and the like.
[0004] 2. Description of the Related Art
[0005] The demand for faster, more powerful integrated circuits
(IC) devices has introduced new challenges for IC fabrication
technology, including the need to etch submicron features on a
substrate, such as a semiconductor wafer, with a good uniformity
across the substrate. For example, deep trench storage structures
used in some dynamic random access memory applications require deep
high aspect ratio trenches to be etched into a semiconductor
substrate. Deep silicone trench etching is typically carried out in
a reactive ion etching (RIE) process.
[0006] FIG. 1 depicts a conventional processing chamber 100
utilized for etching material layers disposed on a substrate 144 to
form features therein. The processing chamber 100 has a substrate
support assembly 148 disposed in an interior volume 106 of the
processing chamber 100. The substrate support assembly 148 includes
an electrostatic chuck 166, a base plate 164 and a facility plate
190. The base plate 164 and the facility plate 190 are electrically
insulated by an insulating material 192 disposed therebetween.
Alternatively, a gap or a space may be defined between the base
plate 164 and the facility plate 190 to provide electrical
insulation. A dielectric insulator ring 120 may be attached to an
edge of the facility plate 190. The electrostatic chuck 166 and the
base plate 164 are generally formed from ceramic or similar
dielectric materials. A heating element 176 is disposed in the
electrostatic chuck 166 or the base plate 164 and is utilized to
control the temperature of a substrate disposed on the substrate
support assembly 148. The heating element 176 is coupled by wires
disposed in a center region of the substrate support assembly 148
to a heater power source 178.
[0007] At least one clamping electrode 180 is disposed in the
electrostatic chuck 166 or the base plate 164. The clamping
electrode 180 is coupled to a chucking RF power source 164 through
the center portion of the substrate support assembly 148. An RF
electrode 182 disposed in one of the electrostatic chuck 166 or
base plate 164 is coupled to one or more RF power sources 184, 186
through a matching circuit 188 through an RF transmission line 150
to maintain a plasma in the processing chamber 100. The RF
transmission line 150 is disposed through the substrate support
assembly 148 in a location that is offset from a center axis of the
substrate support assembly 148. The RF transmission line 150 is
utilized to transmit RF power supplied from the RF power sources
184, 186 to the RF electrode 182. Since some substrate support
utilities occupy the space along the central axis of the substrate
support assembly 148, the RF transmission line 150 is coupled to a
metal plate 154 disposed in the substrate support assembly 148. The
metal plate 154 is utilized to conduct the RF power from the offset
RF transmission line 150 to a central feed through 152 routed
through the center of the substrate support assembly 148.
[0008] Typically, it is desired to apply RF power to the substrate
surface in a manner that produces a uniform electric field across
the substrate surface to promote plasma uniformity. Uniform
distribution of the electric field and dissociated ion plasma
across the substrate surface provides uniform etching behavior
across the substrate surface. In order to maintain uniform electric
field and plasma distribution, it is desired that the RF power is
supplied to the substrate through a center region of the processing
chamber, e.g., either through a showerhead electrode and/or through
a substrate support electrode. As discussed above, the center
portion of the substrate support assembly 148 is occupied by
utilities and/or routing a shaft utilized to actuate lift pins (not
shown). The RF transmission line 150 needs to be offset from the
center of the substrate support assembly 148. Accordingly, in
conventional configurations, the RF transmission line 150 is
typically coupled to the base plate 164 at a position offset to the
center axis of the substrate support assembly 148. The metal plate
154 is therefore utilized to carry the RF power from the offset RF
transmission line 150 to the center region of the substrate support
assembly 148 through the center conduit 152 disposed therein.
[0009] As the top portion 156 of the RF transmission line 150 is
directly below the facility plate 190 at a region 158 offset to the
center axis of the substrate support assembly 148, the electric
field generated around the region 158 is particularly different
from other regions outward from the contacted region 158. For
example, in the region 158 directly above the RF transmission line
150, the electric field is typically weaker than the electric field
spread out in other regions where the RF transmission line 150 is
adjacent but not directly below. The offset the RF transmission
line 150 often results in non-uniform electric field, thereby
creating a skew pattern of the electric filed across the substrate
surface.
[0010] FIG. 2 depicts an electric field distribution measured
across the surface of the substrate 144 positioned on the substrate
support assembly 148 while applying an RF power thereto. The
electric field in the region 158 where the RF transmission line 150
is positioned is comparatively weaker than the electric fields in
other regions 160 across the substrate, resulting in the undesired
skew of the electric field. Skew of the electric field contributes
to non-uniform ion dissociation and plasma distribution across the
substrate surface, thereby causing in poor etching uniformity.
[0011] Therefore, there is a need for an improved apparatus for
providing uniform electric field distribution across a substrate
surface.
SUMMARY
[0012] Embodiments of the invention provide an apparatus, such as a
substrate support assembly, suitable for use in an etch reactor. It
is contemplated that the apparatus may also be utilized in other
types of reactors, such as those for deposition, annealing,
implanting, and other processes where uniform electric fields about
a substrate support are desired.
[0013] Embodiments of the invention provide an apparatus which
provides good RF uniformity within a processing chamber. In one
embodiment, an apparatus includes a substrate support assembly, a
terminal, and a dielectric insulator. The substrate support
assembly has a center passage formed along a center axis. An RF
transmission line comprising s a substantially vertical portion and
a substantially horizontal portion is provided. The terminal is
coupled to the substantially horizontal portion of the RF
transmission line. The dielectric insulator circumscribes the
substantially horizontal portion of the RF transmission line. The
dielectric insulator has a first opening through which the terminal
passes to engage the substantially horizontal portion of the RF
transmission line.
[0014] In another embodiment, a substrate support assembly is
provided that includes an electrostatic chuck, a conductive base,
and a conductive facility plate. A center passage is defined
through the electrostatic chuck, the conductive base and the
conductive facility plate. A terminal is coupled to the facility
plate and to an RF transmission line. A dielectric insulator
circumscribes at least a portion of the RF transmission line. The
dielectric insulator has a first opening through which the terminal
passes to engage the RF transmission line and a second opening
concentrically aligned with the first opening. A housing assembly
secures the dielectric insulator to the facility plate. A high
voltage power feed extends through a hole of the housing assembly,
first and second openings of the dielectric insulator and the
terminal to the chucking electrode, the high voltage power feed is
insulated from the RF transmission line.
[0015] In yet another embodiment, an apparatus includes a substrate
support assembly, an RF transmission line coupled to a bottom of
the substrate support assembly at a region offset to a center axis
of the substrate support assembly, a metal plate coupled to the RF
transmission line configured to deliver RF power transmitted from
the RF transmission line to the substrate support assembly, wherein
the metal plate comprises a plurality of conduits disposed on a
base.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0017] FIG. 1 depicts a sectional view of a conventional processing
chamber;
[0018] FIG. 2 depicts a electric field profile across a substrate
surface disposed in the conventional processing chamber of FIG.
1;
[0019] FIG. 3 depicts a sectional view of one embodiment of a
processing chamber in accordance with the present invention;
[0020] FIG. 4A depicts a sectional view of a substrate support
assembly in accordance with the present invention;
[0021] FIG. 4B depicts a cross sectional view of an RF transmission
line coupled to the substrate support assembly of FIG. 4A;
[0022] FIG. 4C depicts a perspective view of an RF terminal mounted
on the RF transmission line of FIG. 4A;
[0023] FIG. 4D depicts a cross sectional view of a horizontal
passage of the RF transmission line of FIG. 4A;
[0024] FIG. 5A depicts a sectional view of another embodiment of a
substrate support assembly in accordance with the present
invention; and
[0025] FIG. 5B depicts a top view of substrate support assembly of
FIG. 5A.
[0026] 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
and features of one embodiment may be beneficially incorporated in
other embodiments without further recitation.
[0027] It is to be noted, however, that the appended drawings
illustrate only exemplary embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
DETAILED DESCRIPTION
[0028] FIG. 3 depicts a sectional view of one embodiment of
processing chamber 300 that can provide uniform electric field
across a substrate surface, providing a high etching uniformity
across a substrate surface. Although the processing chamber 300 is
shown including a plurality of features that enable superior
etching performance, it is contemplated that other processing
chambers may be adapted to benefit from one or more of the
inventive features disclosed herein, including those used for
non-etching semiconductor processing applications.
[0029] The processing chamber 300 includes a chamber body 302 and a
lid 304 which enclose an interior volume 306. The chamber body 302
is typically fabricated from aluminum, stainless steel or other
suitable material. The chamber body 302 generally includes
sidewalls 308 and a bottom 310. A substrate access port (not shown)
is generally defined in a side wall 308 and selectively sealed by a
slit valve to facilitate entry and egress of the substrate 344 from
the processing chamber 300. An exhaust port 326 is defined in the
chamber body 302 and couples the interior volume 306 to a pump
system 328. The pump system 328 generally includes one or more
pumps and throttle valves utilized to evacuate and regulate the
pressure of the interior volume 306 of the processing chamber 300.
In one embodiment, the pump system 328 maintains the pressure
inside the interior volume 306 at operating pressures typically
between about 10 mTorr to about 20 Torr.
[0030] The lid 304 is sealingly supported on the sidewall 308 of
the chamber body 302. The lid 304 may be opened to allow excess to
the interior volume 306 of the processing chamber 300. The lid 304
includes a window 342 that facilitates optical process monitoring.
In one embodiment, the window 342 is comprised of quartz or other
suitable material that is transmissive to a signal utilized by an
optical monitoring system 340. The optical monitoring system 340 is
positioned to view the substrate 344 positioned on a substrate
support assembly 348 through the window 342. One optical monitoring
system that may be adapted to benefit from the invention is the
EyeD.RTM. full-spectrum, interferometric metrology module,
available from Applied Materials, Inc., of Santa Clara, Calif.
Details of how to use examples of an optical monitoring have been
disclosed in commonly assigned U.S. Application Ser. No.
60/479,601, titled "Method and System for Monitoring an Etch
Process", filed on Jun. 18, 2003, U.S. Pat. No. 6,413,837, titled
"Film Thickness Control Using Spectral Interferometry", issued on
Jul. 2, 2002, and U.S. Application Ser. No. 60/462,493, titled
"Process Control Enhancement and Fault Detection Using In-Situ and
Ex-situ Metrologies and Data Retrieval In Multiple Pass Wafer
Processing", filed on Apr. 11, 2003, all of which are incorporated
by reference in their entireties.
[0031] A gas panel 358 is coupled to the processing chamber 300 to
provide process and/or cleaning gases to the interior volume 306.
In the embodiment depicted in FIG. 3, inlet ports 332', 332'' are
provided in the lid 304 to allow gases to be delivered from the gas
panel 358 to the interior volume 306 of the processing chamber
300.
[0032] A showerhead assembly 330 is coupled to an interior surface
314 of the lid 304. The showerhead assembly 330 includes a
plurality of apertures and a central passage 338 that allow the
gases flowing through the showerhead assembly 330 from the inlet
port 332 into the interior volume 306 of the processing chamber 300
in a predefined distribution across the surface of the substrate
344 being processed in the chamber 300. In one embodiment, the
showerhead assembly 330 is configured with a plurality of zones
that allow for separate control of gas flowing into the interior
volume 306 of the processing chamber 300. In the embodiment
depicted in FIG. 3, the showerhead assembly 330 as an inner zone
334 and an outer zone 336 that are separately coupled to the gas
panel 358 through separate inlets 332.
[0033] A substrate support assembly 348 is disposed in the interior
volume 306 of the processing chamber 300 below the showerhead
assembly 330. The substrate support assembly 348 holds the
substrate 344 during processing. The substrate support assembly 348
generally includes a plurality of lift pins (not shown) disposed
therethrough that are configured to lift the substrate from the
support assembly 348 and facilitate exchange of the substrate 344
with a robot (not shown) in a conventional manner.
[0034] In one embodiment, the substrate support assembly 348
includes an electrostatic chuck 366 attached to a base plate 364.
The electrostatic chuck 366 is disposed on the base plate 364 and
is circumscribed by a focus ring 346. A facility plate 309 is
attached to the base plate 364. The base plate 364 and the facility
plate 309 is electrically insulated by an insulating material 301.
Alternatively, the base plate 364 and the facility plate 309 may be
electrically insulated by a space or a gap formed therebetween. A
dielectric insulating ring 320 is coupled to a bottom surface of
the facility plate 309. Routing utilities, such as fluids, power
lines and sensor leads, among other, are coupled through the
dielectric insulator ring 320 to the base plate 364 and
electrostatic chuck 366.
[0035] At least one of the base plate 364 or electrostatic chuck
366 may include at least one optional embedded heater 376, at least
one optional embedded isolator 374 and a plurality of conduits,
368, 370 to control the lateral temperature profile of the support
assembly 348. The conduits 368, 370 are fluidly coupled to a fluid
source 372 that circulates a temperature regulating fluid
therethrough. The heater 376 is regulated by a power source 378.
The conduits 368, 370 and heater 376 are utilized to control the
temperature of the base plate 364, and heat and/or cool the
electrostatic chuck 366. IN one embodiment, the conduits and the
heater control, at least in part, the temperature of the substrate
344 disposed on the electrostatic chuck 366. The temperature of the
electrostatic chuck 366 and the base plate 364 is monitored using a
plurality of sensors 392 controlled by a controller 350 to detect
temperature in different regions of the electrostatic chuck 366 and
the base plate 364.
[0036] The electrostatic chuck 366 is generally formed from ceramic
or similar dielectric material and comprises at least one clamping
electrode 380 controlled using a chucking power source 382. An RF
electrode 381 is coupled to one or more RF power sources 384, 386
through a conductive feed through 383 through a matching circuit
388 for maintaining a plasma formed form process and/or other gases
within the processing chamber 300. The facility plate 301 is
coupled to the RF power sources 384, 386 through an RF transmission
system 312 to energize the RF electrode 381 through a passage 318
formed in a center portion of the substrate support assembly 348.
The facility plate 309 is fabricated from a conductive material
that may electrically and conductively carry RF power from the RF
power sources 384, 386 through the center passage 318 to the RF
electrode 381 disposed in the electrostatic chuck 366. In the
embodiment, the RF power sources 384, 386 are generally capable of
producing an RF signal having a frequency from about 50 kHz to
about 3 GHz and a power of up to about 10,000 Watts. The matching
network 488 matches the impedance of the sources 384, 386 to the
plasma impedance.
[0037] The passage 318 includes a high voltage (HV) cable 305
coaxially disposed in a conduit 303. The passage 318 facilitates
transmission of chucking power and RF power individually at cable
305 and the conduit 303 formed in the passage. The passage 318
facilitates transmission of the chucking power supplied from the
chucking power source 382 to the chucking electrode 380 and
transmission of RF power supplied from RF power sources 384, 386 to
the RF electrode 381. An RF transmission system 312 is disposed in
the dielectric insulator ring 320 attaching to the facility plate
309. The HV cable 305 in the passage 318 is extended and passing
through a portion of the transmission system 312 to the chucking
power source 382. A housing assembly 316 is coupled to the bottom
of the facility plate 309, circumscribing a bent portion of the RF
transmission system 312. Details of the passage 318, the RF
transmission system 312 and the housing 316 will be further
described with referenced to FIGS. 4A-D.
[0038] FIG. 4A depicts a cross sectional view of an exemplary RF
transmission system 312 coupled to the passage 318 formed in the
substrate support assembly 348. The RF transmission system 312 has
a center axis 406 coupled substantially to align with a center axis
of the substrate support assembly 348. The RF transmission system
312 includes a bent RF transmission line 428, a terminal 410 and
the housing assembly 316 circumscribing a portion of the RF
transmission line 428. The terminal 410 has a central aperture that
allows passage of power feed 420. The power feed 420 having a top
end 414 formed and exposed to connect to a bottom end of the HV
cable 305 disposed in the passage 318 formed in the center of the
substrate support assembly 348. The power feed 420 facilitates
transmission of the chucking power from the chucking power source
382, as shown in FIG. 3, through the HV cable 305 to the clamping
electrode 380 disposed in the electrostatic chuck 366. An insulator
412 may be utilized between the power feed 420 and the terminal 410
to provide a good sealing and electrical insulation. In one
embodiment, the insulator 412 may be fabricated from a dielectric
material, such as plastic, polymer or fluorocarbon, such as TEFLON,
that can provide good sealing as well as electrical insulation.
[0039] In one embodiment, the terminal 410 has a substantially
longitudinal body having a lower portion 418 disposed in the bent
RF transmission line 428 and an upper portion 416 extending upward
and protruded out of the bent RF transmission line 428. The lower
portion 418 of the terminal 410 is electrically isolated from the
power feed 420 disposed therein, for example, by an insulator
sleeve (not shown). The bent RF transmission line 428 has an first
aperture 496 formed and sized to receive the lower portion 418 of
the RF terminal 410 and facilitates conductance of RF power from RF
power sources through the terminal 410 to the RF electrode 381. In
one embodiment, the terminal 410 may be fabricated from conductive
materials, such as copper, aluminum, stainless steel and
combinations thereof.
[0040] In one embodiment, the bent RF transmission line 428
includes a connector 402 and an RF rod 422 that are circumscribed
by a dielectric insulator 424. Referring first to FIG. 4B, the RF
transmission line 428 includes the dielectric insulator 424. The
insulator 424 is comprised of mating shells that circumscribe the
RF rod 422 and connector 402. The dielectric insulator 424 may be
fabricated from a dielectric material, such as plastic, polymer or
TEFLON, which may provide good sealing as well as electrical
insulation.
[0041] The dielectric insulator 424 includes an aperture 482 which
is aligned with an aperture 484. The apertures 482, 484 are aligned
concentrically with the center axis 406. The aperture 484 allows
the terminal 410 to extend through the insulator 424 and mate with
the connector 402. The aperture 482 allows the power feed 420 to
extend up through the bottom of the insulator 424 and extend
concentrically through the terminal 410. The shells 424A, 424B
generally include a mating feature 488 which prevents line of sight
seen between the shells 424A, 424B.
[0042] In the embodiment depicted in FIG. 4B, the mating feature
488 is in the form of a tongue and groove joint. The mating feature
488 may include a press or snap-fit which secures the shells 424A,
424B together.
[0043] The RF rod 422 is fabricated from a material having high
conductivity to facilitate transmission of the RF power from RF
power source 384, 386. In one embodiment, the RF rod 422 may be
fabricated from a metal material selected from a group consisting
of copper, silver, gold, and other suitable metallic materials. The
bent RF transmission line 428 has a substantially L-shape defined
by the connector 402 disposed in a substantially horizontal
orientation which is coupled to the substantially vertical rod
422.
[0044] Referring now to FIG. 4D, connector 402 of the RF
transmission line 428 has the first aperture 496 configured to
receive the lower portion 418 of the terminal 410 and a second
aperture 498 configured to receive the upper end of the rod 422 of
the RF transmission line 428. Detail descriptions of the RF
transmission line 428 and the RF terminal will be further discussed
below with referenced to FIGS. 4C.
[0045] Referring back to FIG. 4A, as the space substantially around
the center axis 406 of the substrate support assembly 348 may be
utilized for routing utilities, sensor leads and the like, or
mechanical support disposed therein, that prevents the positioning
of the RF transmission line 428 directly underneath, the L-shape
and bent configuration of the RF transmission line 428 can
efficiently provide space for routing these utilities while
efficiently delivering RF power through the center of the substrate
support assembly 348. The length 426 of the connector 402 is
sufficient to position the rod 422 offset and clear from the
utilities or other mechanical support centrally disposed underneath
the substrate support assembly 348. In the embodiment wherein the
routing utilities or mechanical support disposed underneath the
center portion of the substrate support assembly 348 have a
relatively smaller size, the length 426 of the connector 402 may be
shorter so as to minimize the lateral offset of the RF power in the
RF transmission line 428. In one embodiment, the length 426 of the
connector 402 is between about 1 inch and about 10 inch, such as
between about 1 inch and about 5 inch, for example, between about 1
inch and about 2 inch.
[0046] The housing assembly 316 is disposed below and in contact
with the dielectric insulating ring 320 having a center opening to
receive the lower portion 418 of the RF terminal 410. The housing
assembly 316 circumscribes the connector 402 and an upper portion
430 of the rod 422 of the RF transmission line 428. In one
embodiment, the housing assembly 316 may be fabricated from a
material that can shield RF power from interaction with the plasma,
ions, or dissociated species during process which may cause
electric field distribution non-uniformity. As the housing assembly
316 can shield RF power, the RF power transmitted through the
connector 402 can be efficiently be shield from interaction with
the plasma generated in the processing chamber 300. In one
embodiment, the housing assembly 316 is fabricated from hard and
non-magnetic stainless steel. The housing assembly 316 has a hole
480 that aligns with the hole 482 of the insulator 424 to allow
passage of the power feed 420 along the axis 406. The housing
assembly 316 secures the upper end of the transmission line 428 to
the support assembly 348. The housing assembly 316 additionally
circumscribes the upper portion of the insulator 424 which covers
the connector 402. Thus, the housing assists in securing the shells
424A, 424B together.
[0047] Thus, the insulator 424 and housing assembly 316
substantially prevents the RF transmission line 428 from direct
contact to the substrate support assembly 348 to avoid localized
electric field non-uniformity. The horizontal portion of the
insulator 424 circumscribing the connector 402 insulator 424 serves
as an electric shield that prevents the electronic magnetic power
from the transmission line 428 from interfering with the electronic
field distribution across the substrate surface during RF power
transmission.
[0048] In one embodiment, an insulator 432 is disposed between the
lower portion 318 of the RF terminal 410 and the housing assembly
428 above the bent RF transmission line 428. The insulator 432
assists filling the gap or interval that may exist among the
dielectric insulating ring 320, the housing assembly 316 and the RF
transmission line 428 and provides a good sealing to adjacent
chamber components.
[0049] FIG. 4C depicts a perspective view of the terminal 410
disposed on the RF transmission line 428. The upper portion 416 of
the terminal 410 has an annual opening utilized to be attached to
the bottom surface of the facility plate 301. The lower portion 418
of the terminal 410 extends through the insulator 432 and mates
with the opening 496 of the RF transmission line 428.
[0050] FIG. 5A depicts of a sectional view of another embodiment of
substrate support assembly 500 that can provide uniform electric
field across a substrate surface. Similar to the configurations of
FIG. 3, the substrate support assembly 500 includes the
electrostatic chuck 366 attached to the base plate 364. The
dielectric insulating ring 320 is coupled to a bottom surface of
the base plate 364. An RF transmission line 508 is attached to the
base plate 364 circumscribed by the dielectric insulating ring 320.
The RF power from the RF transmission line 508 is transmitted to
the substrate support assembly 500 through a metal plate 502
disposed on the dielectric insulating ring 320 connecting to the RF
transmission line 508. As discussed above, routine utilities and/or
some mechanical supports may be disposed around a center axis 506
(as seen in FIG. 5B) below the substrate support assembly 500, the
RF transmission line 508 is therefore desired to be disposed at a
location 520 offset to the center axis 506. By utilizing the metal
plate 502 disposed in the dielectric insulating ring 320, the RF
power from the RF transmission line 508 can be delivered to the
substrate support assembly 500 through the metal plate 502
connected thereto. In order to avoid skew pattern that may occur
due to the offset attachment of the RF transmission line 508, the
metal plate 502 is configured to have multiple conduits 504
protruded upward from a base 510. The conduits 504 are formed
substantially perpendicular to the base 510 utilized to deliver RF
power to different locations of an RF electrode 512 of the
substrate support assembly 500. Each conduits 504 formed in the
metal plate 502 has an end coupled to the RF electrode of the
electrostatic chuck 366 to deliver RF power to different locations
of the substrate support assembly 500. In one embodiment, the metal
plate 502 is fabricated from a metallic material selected from a
group consisting of copper, aluminum, stainless steel and
combinations thereof.
[0051] FIG. 5B depicts a perspective top view of the RF electrode
512 embedded in the electrostatic chuck 366 of the substrate
support assembly 500. The RF transmission line 508 is offset
attached at the region 520 underneath the substrate support
assembly 508, as shown in dotted line. As the offset attachment of
the RF transmission line 508 may result in non-uniform electric
field distribution, the distribution of the conduits 504 is
arranged in a symmetrical manner utilizing an axis 522 passing
through the region 520 as a center axis. The distribution of the
conduits 504 may efficiently alter the electric field distributed
across the substrate surface. The adjustable and alterable conduit
distribution of the metal plate 502 may efficiently control and
redistribute electric field across the surface of the substrate
support assembly. In one embodiment, the adjustable and alterable
conduit distribution of the metal plate 502 resolves the potential
localized and non-uniform electric field profile that may occur due
to the offset attachment of the RF transmission line 508. The
conduits 504 provide different contact points across the RF
electrode 512 of the electrostatic chuck 366 to uniformly delivery
RF power to different locations across the electrostatic chuck
surface so that the influence of the electric field at location 520
above the location of the transmission line 508 is balanced and
negated. Although six conduits 504 are shown in the FIG. 5B, it is
noted that the number, distribution, shape and locations of the
conduits 504 may be arranged in any manner suitable for providing a
uniform profile and distribution of electric field generated from
RF power to balance the effect of the transmission line offset. As
the electric field distribution is controlled and maintained
uniformly across the substrate surface, a uniform etching
performance may be therefore obtained.
[0052] A mixture of process, direct injection and inert gases are
provided to the chamber for plasma etching. The mixture may include
at least one of HBr, NF.sub.3, O.sub.2, SiF.sub.4, SiCl.sub.4 and
Ar. In one embodiment, the process gases provided to the mixing
manifold include HBr and NF.sub.3, while O.sub.2, SiF.sub.4 and
SiCl.sub.4 may optionally be provided. In an exemplary embodiment,
between about 50 to about 500 sccm of HBr, between about 10 to
about 200 sccm of NF.sub.3, between about 0 to about 200 sccm of
O.sub.2, between about 0 to about 200 sccm of SiF.sub.4, between
about 0 to about 200 sccm of SiCl.sub.4, and between about 0 to
about 200 sccm of Ar are provided to the mixing manifold for a
process suitable for etching a 300 mm substrate. The mixed gases
are provided to the plenums at a flow ratio selected commensurate
with the feature density, size and lateral location. SiCl.sub.4 may
be used as a direct injection gas provided to the plenums of the
showerhead assembly bypassing the mixing manifold.
[0053] Various embodiments of the present invention provide an
apparatus and method that provide high etching uniformity across a
substrate surface. The configuration of multiple contact points for
RF power delivery and/or the bent RF transmission line
advantageously provides a manner to compensate electric field skew
pattern that may occurred in the conventional apparatus.
Additionally, the configuration of multiple contact points of RF
power delivery and/or the bent RF transmission line improve the
uniformity of the electric field profile distributed across the
substrate surface and therefore improving the overall etching
uniformity.
[0054] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
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