U.S. patent number RE39,939 [Application Number 11/055,788] was granted by the patent office on 2007-12-18 for processing system.
This patent grant is currently assigned to Tokyo Electron Limited. Invention is credited to Daisuke Hayashi, Koichi Kazama, Nobuyuki Okayama, Jun Ozawa, Hidehito Saegusa, Naoki Takayama.
United States Patent |
RE39,939 |
Okayama , et al. |
December 18, 2007 |
Processing system
Abstract
A processing system has an upper electrode with gas discharge
holes of a shape corresponding to the external we of insulating
members. The insulating members are formed of a poly(ether
etherketone) resin, a polyimide resin, a poly (ether imide) resin
or the like. Each insulating member has a step at its outer surface
and an internal longitudinal through hole tapered to expand toward
the processing chamber. The insulating members are pressed in the
gas discharge holes to bring the steps into contact with shoulders
formed in the sidewalls of the gas discharge holes. A part of each
insulting member, as fitted in the gas discharge hole, projects
from a surface of the upper electrode that faces a susceptor.
Inventors: |
Okayama; Nobuyuki (Nirasaki,
JP), Saegusa; Hidehito (Yamanashi-ken, JP),
Ozawa; Jun (Yamanashi-ken, JP), Hayashi; Daisuke
(Yamanashi-ken, JP), Takayama; Naoki (Kofu,
JP), Kazama; Koichi (Nirasaki, JP) |
Assignee: |
Tokyo Electron Limited
(Tokyo-To, JP)
|
Family
ID: |
14536583 |
Appl.
No.: |
11/055,788 |
Filed: |
April 8, 1998 |
PCT
Filed: |
April 08, 1998 |
PCT No.: |
PCT/JP98/01610 |
371(c)(1),(2),(4) Date: |
October 05, 1999 |
PCT
Pub. No.: |
WO98/46808 |
PCT
Pub. Date: |
October 22, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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10278863 |
Oct 24, 2002 |
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Reissue of: |
09402393 |
Oct 5, 1999 |
06334983 |
Jan 1, 2002 |
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Foreign Application Priority Data
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Apr 11, 1997 [JP] |
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9-110472 |
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Current U.S.
Class: |
156/345.34;
29/592.1 |
Current CPC
Class: |
H01J
37/3244 (20130101); C23C 16/5096 (20130101); H01J
37/32477 (20130101); C23C 16/455 (20130101); C23C
16/45565 (20130101); Y10T 29/49002 (20150115); Y10T
29/532 (20150115); Y10T 29/53204 (20150115); Y10T
29/49117 (20150115) |
Current International
Class: |
H01L
21/306 (20060101) |
Field of
Search: |
;29/592.1,825
;156/345.34 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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61-67922 |
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Sep 1984 |
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JP |
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61-67922 |
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Apr 1988 |
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JP |
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2-45629 |
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Mar 1990 |
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JP |
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2-61078 |
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Mar 1990 |
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JP |
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9-27398 |
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Jan 1997 |
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JP |
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Other References
International Preliminary Examination Report for PCT/JP98/06610,
May 2004. cited by other .
Supplementary European Search Report, issued in connection with EP
98 91 2715, mailed May 7, 2004. cited by other .
Patent Abstracts of Japan, Publication No. 08264462, Publication
Date: Oct. 11, 1996. cited by other.
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Primary Examiner: Mayekar; Kishor
Attorney, Agent or Firm: Smith, Gambrell & Russell,
LLP
Parent Case Text
This application is a .Iadd.division of application No. 10/278,863,
filed Oct. 24, 2002, now abandoned, which is a reissue of U.S. Pat.
No. 6,334,983, which resulted from application No. 09/402,393,
filed Oct. 5, 1999, which was a .Iaddend.35 U.S.C. 371 National
stage filing of .[.PCT/JP/98/0160.]. .Iadd.PCT/JP98/01610.Iaddend.,
filed Apr. 8, 1998. .Iadd.This application is one of three
divisions of co-pending application No. 10/278,863, the other two
divisions being co-pending application No. 10/463,439, filed Jun.
18, 2003, and co-pending application No. 10/463,435, also filed
Jun. 18, 2003..Iaddend.
Claims
what is claimed is:
.[.1. A processing system comprising: a processing vessel defining
an airtight processing chamber; an upper electrode disposed in an
upper region of the processing chamber; a lower electrode disposed
below and opposite to the upper electrode in the processing
chamber; and a radio frequency power source connected at least to
either the upper or the lower electrode; wherein the upper
electrode includes a side facing into the processing chamber
towards the lower electrode, the upper electrode side having a
plurality gas discharge holes to supply a predetermined process gas
therethrough into the processing chamber, resin insulating members,
each provided with a through hole permitting the process gas to
pass through, are fitted from the upper electrode side facing the
processing chamber into the gas discharge holes, respectively, each
of the gas discharge holes is provided with a shoulder, each of the
insulating members is provided with a step, and each of the
insulating members are positioned in the gas discharge hole with
its step in contact with the shoulder of the gas discharge
hole..].
.[.2. The processing system according to claim 1, wherein the
insulating members are fitted in the gas discharge holes of the
upper electrode to project into the processing chamber..].
.[.3. The processing system according to claim 1, wherein each of
the insulating members is provided with a flange capable of
covering the rim of an end of the gas discharge hole on the side of
the processing chamber..].
.[.4. The processing system according to claim 1, wherein at least
part of the sidewall of each of the gas discharge holes between an
open end thereof on the side of the processing chamber and the
shoulder thereof is finished by a plasma-proofing process, and a
part of the sidewall of each gas discharge hole between the
shoulder and the open end opening into a gas supply passage is not
finished by the plasma-proofing process..].
.[.5. The processing system according to claim 4, wherein the
insulating members are formed of a resin..].
.[.6. The processing system according to claim 1, wherein each of
the insulating members has a length and the length of the
insulating members is shorter than that of the gas discharge
holes..].
.[.7. The processing system according to claim 1, wherein at least
part of the through hole of each insulating member is substantially
tapered so as to expand toward the processing chamber..].
.[.8. A processing system comprising: a processing vessel defining
an airtight processing chamber; an upper electrode disposed in an
upper region of the processing chamber; a lower electrode disposed
below and opposite to the upper electrode in the processing
chamber; and a radio frequency power source connected at least to
either the upper or the lower electrode; wherein the upper
electrode has an upper electrode member and a cooling plate
disposed on the upper electrode member, the upper electrode member
and the cooling plate are provided with a plurality of gas
discharge holes through which a predetermined process gas is
supplied into the processing chamber, resin insulating members,
each provided with a through hole permitting the process gas to
flow through, are fitted into the gas discharge holes to cover the
sidewalls of the gas discharge holes, each of the discharge holes
being formed as a through hole passing through the upper electrode
member and the cooling plate, each of the gas discharge holes of
the cooling plate is provided with a shoulder, each of the
insulating members is provided with a step, and the insulating
members are positioned in the gas discharge holes with the steps
thereof resting on the shoulders of the corresponding gas discharge
holes, each of the insulating members is fitted into the cooling
plate from an opposite side to the upper electrode member..].
.[.9. The processing system according to claim 8, wherein at least
an end part of the through hole of each insulating member on the
side of the processing chamber is substantially tapered to expand
toward the processing chamber..].
.Iadd.10. A method of use of an upper electrode disposable in an
upper region of a processing chamber, said upper electrode provided
with a plurality of gas discharge holes to supply a predetermined
process gas therethrough into the processing chamber; each of the
gas discharge holes provided with a shoulder; and resin insulating
members, each provided with a through hole permitting a process gas
to pass through and a step, said method comprising the steps of
inserting one of said insulating members into one of said gas
discharge holes; pressing said one insulating member in said one
hole such that said step of said insulating member contacts said
shoulder of said one hole such that an edge of said one hole is not
exposed to plasma produced in the chamber; and repeating said
inserting and pressing steps until all said gas discharge holes of
said upper electrode have been provided each with the insulating
member..Iaddend.
.Iadd.11. The method according to claim 10, wherein said insulating
members are pressed into said gas discharge holes to project into
the processing chamber..Iaddend.
.Iadd.12. The method according to claim 10, wherein each of said
insulating members is provided with a flange capable of covering a
rim of an end of each of said gas discharge holes..Iaddend.
.Iadd.13. The method according to claim 10, further comprising the
steps of performing a plasma-proofing process on at least part of a
sidewall of each of said gas discharge holes between an open end
thereof on a side of the processing chamber and said shoulder
thereof, and omitting performance of said plasma-proofing process
at a part of said sidewall of each said gas discharge holes between
said shoulder and an open-end thereof opening into a gas supply
passage..Iaddend.
.Iadd.14. The method according to claim 13, further comprising the
step of providing resin members as said insulating
members..Iaddend.
.Iadd.15. The method according to claim 14, wherein said resin
insulating members are inserted and pressed into said gas discharge
holes, respectively, from a side of the processing
chamber..Iaddend.
.Iadd.16. The method according to claim 10, further comprising the
steps of providing said insulating members so that they have a
length that is relatively shorter than that of said gas discharge
holes..Iaddend.
.Iadd.17. The method according to claim 10, further comprising the
step of providing said insulating members so that at least part of
the through hole of each said insulating members is substantially
tapered to expand toward said processing chamber..Iaddend.
Description
TECHNICAL FIELD
The present invention relates to a processing system, such as an
etching system.
BACKGROUND ART
A prior art etching system is provided with an upper electrode and
a susceptor serving as a lower electrode disposed opposite to each
other in a processing chamber formed in an airtight processing
vessel. When subjecting a workpiece to a predetermined etching
process by this etching system, the workpiece is mounted on the
susceptor, a predetermined process gas is supplied into the
processing chamber and the workpiece is etched for the
predetermined etching process by a plasma produced in the
processing chamber by applying a predetermined radio frequency
power across the upper electrode and the susceptor. The process gas
is supplied through a gas supply pipe connected to gas sources, for
example, into a space defined between the upper electrode and an
upper electrode holding member holding the upper electrode, and
then the process gas is discharged through a plurality of gas
discharge holes formed in the upper electrode into the processing
chamber.
Since a surface of the upper electrode facing the susceptor is
exposed to the plasma, it is possible that an electric field is
concentrated on the gas discharge holes, more specifically on the
edges of the gas discharge holes on the side of the processing
chamber, whereby the edges of the gas discharge holes are etched
and particles are produced. If the particles adhere to the
workpiece, the yield of the products of the etching system is
reduced. A technique disclosed in, for example, JP-A No. 61-67922
inserts insulating members each provided with a through hole and
formed of a ceramic material, such as alumina, or a fluorocarbon
resin, such as Teflon in the gas discharge holes to prevent the
concentration of an electric field on the gas discharge holes. The
gas discharge holes are tapered toward the processing chamber, and
the insulating members substantially tapered so as to conform with
the tapered gas discharge holes are inserted downward from the
upper end of the gas discharge holes in the gas discharge holes.
The insulating members are fitted in the gas discharge holes so
that the lower end surfaces thereof on the side of the processing
chamber are flush with the surface of the upper electrode facing
the susceptor. Thus, the insulating members are not caused to fall
off the upper electrode toward the lower electrode by the pressure
of the process gas, and prevent the concentration of an electric
field on the gas discharge holes.
Since the insulating members are inserted in the gas discharge
holes from the upper side of the upper electrode, the upper
electrode needs to be removed from the processing vessel every time
the insulating members are changed and hence the work for changing
the insulating members takes much time, the operating time of the
etching system is reduced accordingly, reducing the throughput of
the etching system. Since the processing chamber is heated at a
high temperature during the processing operation of the etching
system, thermal stress is induced in the upper electrode.
Consequently, the gas discharge holes and the insulating members
are strained and, sometimes, the lower end surfaces of the
insulating members on the side of the processing chamber are
dislocated from a plane including the lower surface of the upper
electrode facing the lower electrode.
Sometimes, the edges of the through holes of the insulating member
on the side of the processing chamber are etched by the plasma
produced in the processing chamber and particles are produced.
Since the insulating members are made of alumina or a fluorocarbon
resin, it is possible that particles of aluminum or the
fluorocarbon resin are produced, and the particles adhere to the
workpiece and exert adverse effects, such as the reduction of
insulating strength, on the workpiece.
In a processing system provided with an upper electrode comprising
an upper electrode member and a cooling plate placed on the upper
electrode member, both the upper electrode member and the cooling
plate are provided with a plurality of gas discharge holes. In this
processing system, a plasma produced in a processing chamber flows
through the gas discharge holes formed in the upper electrode
member and the gas discharge holes of the cooling plate are damaged
by the plasma.
DISCLOSURE OF THE INVENTION
The present invention has been made in view of the foregoing
problems in the prior art processing systems and it is therefore an
object of the present invention to provide a novel, improved
processing system provided with insulating members capable of being
easily attached and changed and of being easily and uniformly
positioned.
The present invention is applied to a processing system comprising
a processing vessel defining an airtight processing chamber, upper
and lower electrodes disposed opposite to each other in the
processing chamber, and constructed to supply a predetermined
process gas through a plurality of gas discharge holes formed in
the upper electrode into the processing chamber. According to a
first aspect of the present invention, insulating members each
provided with a through hole permitting a process gas to pass
through are fitted in the gas discharge holes, respectively, from
the side of the processing chamber. Since the insulating members
are inserted and fitted in the gas discharge holes through the
outlet ends (ends on the side of the processing chamber) of the gas
discharge holes, the insulating members can easily be attached to
the upper electrode and easily be changed.
According to a second aspect of the present invention, the
insulating members are fitted in the gas discharge holes of the
upper electrode so as to project from the lower surface of the
upper electrode facing the lower electrode into the processing
chamber. Since lower end parts of the insulating members project
from the lower surface of the upper electrode facing the lower
electrode, the edges of ends of the gas discharge holes on the side
of the processing chamber are not exposed to the processing
chamber. Consequently, the edges not exposed to the processing
chamber are not etched by a plasma produced in the processing
chamber for a processing operation.
According to a third aspect of the present invention, each of the
insulating members is provided with a flange capable of covering
the rim of an end of the gas discharge hole on the side of the
processing chamber. When the insulating members are fitted in the
gas discharge holes, respectively, the flanges cover the rims of
the ends of the gas discharge holes on the side of the processing
chamber. Therefore, the edges of the ends of the gas discharge
holes on the side of the processing chamber are not exposed to a
plasma produced in the processing chamber and will not be etched.
Thus, the life of the upper electrode provided with the gas
discharge holes can greatly be extended.
According to a fourth aspect of the present invention, each of the
gas discharge holes is provided with a shoulder, each of the
insulating members is provided with a step, and the insulating
members are fitted in the gas discharge holes so that the
insulating members are positioned in place in the gas discharge
holes with the steps thereof resting on the shoulders of the
corresponding gas discharge holes. Since the insulating members are
pressed into the gas discharge holes so that the steps are pressed
against the shoulders of the gas discharge holes, the insulating
members can correctly be positioned. Consequently, all the
insulating members can be positioned at desired positions in the
gas discharge holes. Since the steps of the insulating members are
in close contact with the shoulders of the gas discharge holes, the
plasma is unable to leak into a gas supply passage connected to the
gas discharge holes.
According to a fifth aspect of the present invention, at least a
part of the sidewall of each of the gas discharge holes between the
open end thereof on the side of the processing chamber and the
shoulder thereof is finished by a plasma-proofing process, such as
an anodic oxidation process if the upper electrode is formed of
aluminum. Therefore, the sidewalls of the gas discharge holes are
not etched even if the plasma infiltrates into gaps between the
sidewalls of the gas discharge holes and the insulating members.
Since a part of the sidewall of each gas discharge hole between the
shoulder and the open end opening into the gas supply passage is
not finished by the plasma-proofing process, the outer surfaces of
the insulating members and the sidewalls of the corresponding gas
discharge holes are in airtight contact with each other. Therefore,
the insulating members will not come off the gas discharge holes
even if the pressure of the gas acts on the insulating members.
According to a sixth aspect of the present invention, the length of
the insulating members is shorter than that of the gas discharge
holes. When each insulating member is fitted in the gas discharge
hole, a space is formed between the insulating member fitted in the
gas discharge hole and the gas supply passage. Therefore, an
optimum conductance can be secured and the process gas can be
discharged in a desired mode through the through holes of the
insulating members into the processing chamber.
According to a seventh aspect of the present invention, at least a
part of the through hole of each insulating member is substantially
tapered so as to expand toward the processing chamber. Since any
edge is not formed in the open end of through hole on the side of
the processing chamber, the insulating members have improved plasma
resistance, and insulating member changing period can greatly be
extended. Since the parts of the through holes of the insulating
members are tapered so as to expand toward the processing chamber,
the process gas can uniformly be distributed over a workpiece
placed in the processing chamber.
According to an eighth aspect of the present invention, the
insulating members are formed of a resin, such as a poly (ether
ether ketone) resin of the formula (1), such as PEEK PK-450
commercially available from Nippon Poripenko K.K. or PEEK PK-450G
commercially available from The Polymer Corp., a polyimide resin of
the formula (2), such as VESPEL SP-1 commercially available from
DuPont, or a poly(ether imide) resin of the formula (3), such as
ULTEM UL-1000 (natural grade) commercially available from Nippon
Poripenko K.K. or The polymer Corp. ##STR00001##
The insulating members has an improved plasma resistance,
insulating member changing period can greatly be extended, and
influence on the workpiece can be limited to the least extent even
if the insulating members are etched by the plasma.
According to a ninth aspect of the present invention, a processing
system comprises: a processing vessel having an airtight processing
chamber, an upper electrode disposed in an upper region of the
processing chamber, and a lower electrode disposed below and
opposite to the upper electrode in the processing chamber; wherein
the upper electrode has an upper electrode member and a cooling
plate disposed on the upper electrode member, the upper electrode
member and the cooling plate are provided with a plurality of gas
discharge holes through which a predetermined process gas is
supplied into the processing chamber, and insulating members each
provided with a through hole permitting the process gas to flow
through are fitted in the gas discharge holes so as to cover the
sidewalls of the gas discharge holes. Thus, it is possible to
prevent the etching of the sidewalls of the gas discharge holes of
the cooling plate by a plasma produced in the processing
chamber.
According to a tenth aspect of the present invention, at least an
end part of the through hole of each insulating member on the side
of the processing chamber is substantially tapered so as to expand
toward the processing chamber. The insulating members provided with
the through holes having the substantially tapered parts,
respectively, are not easily etched, and insulating member changing
period can be extended.
According to an eleventh aspect of the present invention, each of
the gas discharge holes of the cooling plate is provided with a
shoulder, each of the insulating members is provided with a step,
and the insulating members are fitted in the gas discharge holes so
that the insulating members are positioned in place in the gas
discharge holes with the steps thereof resting on the shoulders of
the corresponding gas discharge holes. Since the insulating members
are pressed into the gas discharge holes so that the steps are
pressed against the shoulders of the gas discharge holes, the
insulating members can correctly be positioned. Consequently, all
the insulating members can be positioned at a desired position in
the gas discharge holes of the cooling plate.
As mentioned above, according to the present invention, the
insulating members are fitted in the gas discharge holes,
respectively, of the upper electrode from the side of the outlet
ends of the gas discharge holes (from the side of the processing
chamber). Therefore, the insulating members can easily be attached
to and removed from the upper electrode. Since the insulating
members are positioned in place in the gas discharge holes with the
steps thereof resting on the shoulders of the corresponding gas
discharge holes, the insulating members can uniformly be disposed
in the gas discharge holes. Since any edge is not formed in a part
of each insulating member exposed to the atmosphere of the
processing chamber and a part of the through hole of each
insulating member is substantially tapered so as to expand toward
the processing chamber, the insulating members are not easily
etched and insulating member changing period can be extended. The
insulating members formed of a predetermined resin have improved
plasma resistance and extend insulating member changing period.
Since a part of each of the sidewalls of the gas discharge holes
between the open end thereof on the side of the processing chamber
and the shoulder thereof is finished by a plasma-proofing process,
and edges of the open ends of the gas discharge holes on the side
of the processing chamber are covered with the insulating members,
the life of the upper electrode can be extended.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic sectional view of an etching system in a
first embodiment according to the present invention;
FIG. 2 is a schematic enlarged sectional view of a part of the
etching system of FIG. 1 around a gas discharge hole;
FIG. 3 is a schematic perspective view of an insulating member
employed in the etching system of FIG. 1;
FIG. 4 is a schematic sectional view of am insulating member in a
modification of the insulating member shown in FIG. 3;
FIG. 5 is a schematic sectional view of an insulating member in
another modification of the insulating member shown in FIG. 3;
FIG. 6 is a schematic sectional view of a part of an etching system
in another embodiment according to the present invention around gas
discharge holes; and
FIG. 7 is an enlarged sectional view of a part of FIG. 6 around a
gas discharge hole.
BEST MODE FOR CARRYING OUT THE INVENTION
Processing systems in preferred embodiments according to the
present invention as applied to etching systems will be described
with reference to the accompanying drawings, in which parts of
substantially the same functions and the same formation will be
designated by the same reference characters and the duplicate
description thereof will be omitted.
FIG. 1 is a schematic sectional view of an etching system 100 in a
first embodiment according to the present invention. The etching
system 100 has a substantially cylindrical processing vessel 104
of, for example, aluminum having surfaces finished by an anodic
oxidation process, defining a processing chamber 102 and capable of
being sealed in an airtight fashion. The processing vessel 104 is
connected to a ground by a grounding line 106. An insulating
support plate 108 of, for example, a ceramic material is disposed
in the bottom of the processing chamber 102. A substantially
cylindrical susceptor 110 serving as a support for supporting a
workpiece, such as a 12 in. diameter semiconductor wafer W
(hereinafter referred to simply as "wafer") W, and as a lower
electrode is disposed on the insulating support plate 108.
The susceptor 110 is supported on a lifting shift 112 extending
through the insulating support plate 108 and the bottom wall of the
processing vessel 104. The lifting shaft 112 is connected to a
driving mechanism, not shown, disposed outside the processing
vessel 104. The driving mechanism moves the susceptor 110 in
vertical directions as indicated by the arrows in FIG. 1. An
elastic airtight sealing member, such as a bellows 114, is extended
between the susceptor 110 and the insulating support plate 108 so
as to surround the lifting shaft 112.
The susceptor 110 is formed of, aluminum and has surfaces finished
by an anodic oxidation process. A coolant circulating passage 116
is formed in the susceptor 110. The coolant circulating passage 116
is connected to a coolant source, not shown, disposed outside the
processing vessel 104 by a coolant supply pipe 116a and a coolant
discharge pipe 116b. A coolant, such as ethylene glycol, is
circulated through the coolant circulating passage and the coolant
source. The susceptor 110 is internally provided with a heating
device, not shown, such as a ceramic heater, and a temperature
sensor, not shown. The heating device, the temperature sensor and
the coolant circulating passage 116 cooperate to maintain the wafer
W automatically at a desired temperature.
An electrostatic chuck 118 for attracting and holding the wafer W
is mounted on a mounting surface of the susceptor 110. The diameter
of the electrostatic chuck 118 is substantially equal to that of
the wafer W. The electrostatic chuck 118 is formed by sandwiching
an electrically conductive thin film 118a such as a tungsten thin
film, between insulating members 118b of, for example, a ceramic
material. The thin film 118a is connected to a variable dc power
supply 120. When a high dc voltage in the range of, for example,
1.0 to 2.5 kV is applied to the thin film 118a by the variable dc
power supply 120, Coulomb's force and Johonson-Rahbeck force are
generated in the insulating members 118b and electrostatic chuck
118 attracts the wafer W mounted thereon to its support surface and
holds the wafer W in place. A plurality of heat transfer gas
jetting holes 122 opens in the support surface of the electrostatic
chuck 118. The heat transfer gas jetting holes 122 are connected to
a heat transfer gas source, not shown, by a heat transfer gas
supply pipe 124. When processing the wafer W, a heat transfer gas,
such as He gas, is jetted through the heat transfer gas jetting
holes 122 into minute spaces between the back surface of the wafer
W mounted on the electrostatic chuck 118 and the support surface to
transfer heat generated in the wafer W efficiently to the susceptor
110.
The electrostatic chuck 118 is provided with a through hole, not
shown, and a lifting pin is inserted in the through hole so as to
be vertically movable. The lifting pin can be projected form and
retracted beneath the support surface of the electrostatic chuck
118. The lifting pin operates to transfer the wafer W in a desired
mode between a carrying arm, not shown, and the support
surface.
A substantially annular focus ring 126 of, for example, quartz is
disposed in a peripheral part of the mounting surface of the
susceptor 110 so as to surround the electrostatic chuck 118. The
focus ring 126 enables a plasma to fall effectively on the wafer W
for the uniform processing of the wafer W.
An upper electrode 128 is disposed opposite to the mounting surface
of the susceptor 110. The upper electrode 128 is made of an
electrically conductive material, such as aluminum, in a shape
substantially resembling a disk, and has surfaces finished by an
anodic oxidation process. The upper electrode 128 is attached
closely to an upper electrode support member 130 of an electrically
conductive material. The upper electrode 128 and the upper
electrode support member 130 are held by a substantially annular
insulating ring 132 attached to the top wall 104a of the processing
vessel 104.
A recess is formed in a surface of the upper electrode support
member 130 facing the upper electrode 128 to define a space 134
between the upper electrode support member 130 and the upper
electrode 128 as attached to the upper electrode support member
130. A gas supply pipe 136 is connected to a part of the upper
electrode support member 130 corresponding to a central region of
the space 134. The gas supply pipe is connected through a valve 138
and a flow controller (MFC) 140 to a gas source 142.
The upper electrode 128 is provided with a plurality of gas
discharge holes 128a connecting the space 134 to the processing
chamber 102. Insulating members 144 relevant to this embodiment are
fitted in the gas discharge holes 128a, respectively.
The insulating members 144 relevant to this embodiment will be
described. The insulating members are formed of a plasma-resistant
resin, such as a poly(ether ether ketone) resin of the formula (1),
a polyimide resin of the formula (2) or a poly(ether imide) resin
of the formula (3). ##STR00002##
The plasma resistance of the insulating members 144 will be
described below. The poly(ether ether ketone) resin of the formula
(1), the polyimide resin of the formula (2), the poly(ether imide)
resin of the formula (3), a polytetrafluoroethylene resin
(fluorocarbon resin) of the formula (4) and a
polychlorotrifluoroethylene resin (fluorocarbon resin) of the
formula (5) were subjected to etching under the following etching
conditions and the etch rates of those resins were measured. (1)
Process gases: CHF.sub.3:CF.sub.4:Ar=20:40:60 (sccm) (2) Pressure
in the processing chamber: 300 mrTorr (3) Plasma producing radio
frequency power: 1.5 kW
The etch rate ratios between the measured etch rates of the resins
were calculated.
Calculated etch rate ratios (1) Polytetrafluoroethylene/Poly(ether
ether ketone)=17.5 (2) Polytetrafluoroethylene/polyimide=16.5 (3)
Polytetrafluoroethylene/Poly(ether imide)=14.1 (4)
Polychlorotrifluoroethylene/Poly(ether ether ketone)=52.4 (5)
Polychlorotrifluoroethylene/Polyimide=49.4 (6)
Polychlorotrifluoroethylene/Poly(ether imide)=42.2
It is known from those etch rates that the poly(ether ether ketone)
resin, the polyimide resin and the poly(ether imide) resin for
forming the insulating members 144, as compared with the
polytetrafluoroethylene resin and the polychlorotrifluoroethylene
resin, which are fluorocarbon resins, are very highly resistant to
etching. It is considered that fluorocarbon resins including the
polytetrafluoroethylene resin and the polychlorotrifluoroethylene
resin are easily etched because fluorocarbon resins are highly
reactive with and easily dissociated by process gases containing
fluorine and generally used for etching processes, such as
CF.sub.4, CHF.sub.3 and CH.sub.2F.sub.2.
The shape of the insulating members 144, and the shape of the gas
discharge holes 128a in which the insulating members 144 are fitted
will be described with reference to FIGS. 2 and 3.
The insulating member 144 has a substantially T-shaped longitudinal
section as shown in FIG. 2, and is provided with a step 144a as
shown in FIGS. 2 and 3. The insulating member 144 has an expanded
part 144b of a relatively great diameter on one side of the step
144a, and a reduced part 144c of a relatively small diameter on the
other side of the step 144a. The insulating member 144 has a length
shorter than that of the gas discharge hole 128a.
The insulating member 144 is provided with a longitudinal through
hole 144d. An end part of the through hole 144d opening in the
expanded part 144b is substantially tapered so as to expand toward
its open end. Therefore, the process gas can be discharged in a
desired mode through the through hole 144d, the sidewall of the
tapered part of the through hole 144d is hardly etched and hence
insulating member changing period at which the insulating members
144 are changed can be extended. Edges of the insulating member 144
which will be exposed to the atmosphere of the processing chamber
102 when the insulating member 144 is fitted in the gas discharge
hole 128a are rounded, which further enhances the etch resistance
of the insulating member 144 and further extends insulating member
changing period.
As shown in FIG. 2, the gas discharge hole 128a has a shape fitting
the insulating member 144. A shoulder 128b is formed in the gas
discharge hole 128a at a position corresponding to the step 144a of
the insulating member 144. A part of the gas discharge hole 128a on
the side of the processing chamber 102 with respect to the shoulder
128b has a diameter corresponding to that of the expanded part 144b
of the insulating member 144, and another part of the gas discharge
hole 128a on the side of the space 134 with respect to the shoulder
128b has a diameter corresponding to that of the reduced part 144c
of the insulating member 144. A part of the sidewall of the gas
discharge hole 128a between the open end opening into the
processing chamber 102 and the shoulder 128b is finished by a
plasma-proofing process, such as an anodic oxidation process by
which the surfaces of the upper electrode 128 are finished.
Therefore, the sidewalls of the gas discharge holes are not etched
even if the plasma infiltrates into gaps between the sidewalls of
the gas discharge holes 128a and the insulating members 144.
A method of fitting the insulating member 144 in each of the
plurality of gas discharge holes 128a will be described below. The
insulating member 144 is inserted in the gas discharge hole 128a
from the side of the outlet end of the gas discharge hole 128a,
i.e., from the side of the processing chamber 102. The insulating
member 144 is pressed so that the step 144a of the insulating
member 144 comes into contact with the shoulder 128b of the gas
discharge hole 128a. Thus, the insulating members 144 can easily be
positioned and can uniformly be arranged in the gas discharge holes
128a.
A part of the gas discharge hole 128a between the shoulder 128b and
an open end opening into the space 134 is not finished by a
plasma-proofing process, because fine irregularities are formed in
the sidewall of the gas discharge hole 128a if the sidewall of the
gas discharge hole 128a is finished by a plasma-proofing process,
such as anodic oxidation process, and the closeness of contact
between the sidewall of the gas discharge hole 128a and the outer
surface of the reduced part 144c of the insulating member 144 is
deteriorated. Thus, the outer surface of the reduced part 144c of
the insulating member 144 is in close contact with the sidewall of
the gas discharge hole 128a. Consequently, the plasma is unable to
infiltrate into gaps between the sidewalls of the gas discharge
holes 128a and the insulating members 144, and the insulating
members 144 will not be caused to come off the gas discharge holes
128a by the pressure of the process gas.
When the insulating member 144 is fitted in the gas discharge hole
128a, a part of the insulating member 144 projects from a surface
of the upper electrode 128 facing the susceptor 110 as shown in
FIG. 2. Therefore, the edge of the open end of the gas discharge
hole 128a on the side of the processing chamber 102 is not exposed
to the plasma produced in the processing chamber 102 and is
protected from etching, so that upper electrode changing period at
which the upper electrode 128 is changed can be extended. When the
insulating member 144 is fitted in the gas discharge hole 128a, a
space is formed between the insulating member 144 and the space 134
extending over the upper electrode 128.
An insulating member 200 shown in FIG. 4 may be fitted instead of
the foregoing insulating member 144 in the gas discharge hole
128a.
The insulating member 200 is formed by additionally providing the
insulating member 144 with a flange 200a around the part of the
insulating member 144 that projects from the upper electrode 128
into the processing chamber 102 when the insulating member 144 is
fitted in the gas discharge hole 128a. The insulating member 200 is
substantially identical in shape with the insulating member 144,
except that the insulating member 200 is provided with the flange
200a. When the insulating member 200 is fitted in the gas discharge
hole 128a, the flange 200a of the insulating member 200 covers
closely the edge of an open end of the gas discharge hole 128a on
the side of the processing chamber 102 and the rim of the open end
of the same. Consequently, the edge of the open end of the gas
discharge hole 128a on the side of the processing chamber 102 is
not exposed to the plasma and is not etched, which extends the life
of the upper electrode 128 provided with the gas discharge holes
128a greatly.
An insulating member 210 shown in FIG. 5 may be fitted instead of
the insulating members 144 and 200 in the gas discharge hole
128a.
The insulating member 210 has a flange 210a corresponding to the
flange 200a of the insulating member 200 and does not have any part
corresponding to the step 144a of the insulating member 200. The
insulating member 200 is positioned by either bringing the step
144a into contact with the shoulder 128b or bringing the flange
200a into contact with the surface of the upper electrode 128. The
insulating member 210 is positioned only by bringing the flange
210a into contact with the surface of the upper electrode 128.
When the insulating member 210 is fitted in the gas discharge hole
128a, the flange 210a of the insulating member 210 covers closely
the edge of an open end of the gas discharge hole 128a on the side
of the processing chamber 102 and the rim of the open end of the
same. Consequently, the edge of the open end of the gas discharge
hole 128a on the side of the processing chamber 102 is not exposed
to the plasma and is not etched, which extends the life of the
upper electrode 128 provided with the gas discharge holes 128a
greatly.
A method of supplying a process gas into the processing chamber 102
will be described below.
A predetermined process gas, such as a mixed gas of CF.sub.4 gas
and O.sub.2 gas when processing a silicon dioxide film, is supplied
from the gas source 142 (FIG. 1) through the gas supply pipe 136
provided with the flow controller (MFC) 140 and the valve 138 into
the space 134. The process gas fills up the space 134 and the
spaces in the gas discharge holes 128a. Consequently, an optimum
conductance can be secured. The process gas flows from the spaces
in the gas discharge holes 128a through the through holes 144d into
the processing chamber and is distributed uniformly in a desired
mode over the wafer W mounted on the susceptor 110.
Referring again to FIG. 1, an exhaust pipe 146 has one end
connected to a lower part of the side wall of the processing vessel
104, and the other end connected to a vacuum pump (P) 148, such as
a turbo-molecular pump. The vacuum pump 148 operates to evacuate
the processing chamber 102 to a predetermined reduced pressure,
such as a vacuum in the range of several millitorrs to several
hundreds millitorrs and to maintain the predetermined vacuum.
A radio frequency power supply system included in the etching
system 100 will be described below. A first radio frequency
generator 152 is connected through a first matching circuit 150 to
the upper electrode 128. A second radio frequency generator 156 is
connected through a second matching circuit 154 to the susceptor
110. In operation, the first radio frequency generator 150 supplies
plasma producing radio frequency power of, for example, 13.56 MHz
to the upper electrode 128. Then, the process gas supplied into the
processing chamber 102 is dissociated and a plasma is produced. At
the same time, the second radio frequency generator 156 supplies a
predetermined bias radio frequency power of, for example, 380 kHz
to the susceptor 110 to attract the plasma effectively to the
surface to be processed of the wafer W.
The present invention is not limited to the etching system 100 and
may be embodied, for example, in an etching system provided with an
upper electrode to which radio frequency power is supplied, and a
susceptor and a processing vessel connected to a ground or an
etching system provided with a susceptor to which radio frequency
power is supplied, and an upper electrode and a processing vessel
connected to a ground.
The insulating members 144 of the etching system in this embodiment
thus constructed are fitted in the gas discharge holes 128a through
the outlet ends thereof on the side of the processing chamber 102.
Therefore, the insulating members 144 can easily be changed. Since
the insulating members 144 are positioned by bringing the steps
144a thereof into contact with the shoulders 128b of the gas
discharge holes 128a, the insulating members 144 can easily be
positioned and can uniformly be arranged. Since any edge is not
formed in a part of each insulating member 144 exposed to the
atmosphere of the processing chamber 102 and a part of the through
hole 144d of each insulating member 144 is substantially tapered,
the insulating members have improved etch resistance and insulating
member changing period can be extended. The insulating members
formed of the foregoing resin have improved plasma resistance and
extend insulating member changing period. Since a part of the
sidewall of each gas discharge hole 128a between the open end
thereof on the side of the processing chamber 102 and the shoulder
128b thereof is finished byaplasma-proofing process, and edges of
the open ends of the gas discharge holes 128a on the side of the
processing chamber 102 are covered with the insulating members 144,
upper electrode changing period at which the upper electrode 128 is
changed can be extended.
An upper electrode 228 of a construction different from that of the
upper electrode 128 of the etching system 100 shown in FIG. 1 will
be described with reference to FIGS. 6 and 7.
The upper electrode 228 is applied to an etching system having a
plasma processing ability higher than that of the etching system
100 shown in FIG. 1. In the following description, components of
the upper electrode 228 substantially the same in function and
construction as those of the upper electrode 128 will be designated
by the same reference characters and the description thereof will
be omitted to avoid duplication.
The upper electrode 228 comprises a silicon electrode (upper
electrode member) 301 disposed opposite to a mounting surface of a
susceptor 110, and a cooling plate 302 of an aluminum alloy bonded
to the upper surface of the silicon electrode 301.
The silicon electrode 301 is provided with a plurality gas
discharge holes 301a. The cooling plate 302 is provided with a
plurality of gas discharge holes 302a of a diameter greater than
that of the gas discharge holes 301a. The gas discharge holes 301a
and the gas discharge holes 302 are coaxial, respectively. A space
134 communicates with a processing chamber 102 by means of the gas
discharge holes 301a and 302a.
Each of the gas discharge holes 302 has a cylindrical, reduced
lower part, and a cylindrical expanded upper part. The reduced
lower part and the expanded upper part are demarcated by a shoulder
302b.
Insulating members 244 of the same material as the insulating
member 144 are fitted in the gas discharge hole 302a, respectively,
so as to be replaceable when damaged.
Referring to FIG. 7, the insulating member 244 has a cylindrical,
reduced lower part 244a, and a cylindrical expanded upper part
244b. The reduced lower part 244a and the expanded upper part 244b
are demarcated by a step 244f. The cylindrical, reduced lower part
244a is fitted in the cylindrical, reduced lower part of the gas
discharge hole 302a, and the cylindrical expanded upper part 244b
is fitted in the cylindrical, expanded upper part of the gas
discharge hole 302a.
The length of the insulating member 244 is approximately equal to
the thickness of the cooling plate 302. The lower end surface of
the insulating member 244 is substantially in contact with the
upper surface of the silicon electrode 301. The length of the
insulating member 244 may be smaller than the thickness of the
cooling plate 302, provided that the lower end surface of the
insulating member 244 is substantially in con tact with the upper
surface of the silicon electrode 301. The cylindrical, reduced
lower part 244a is provided with a small hole 244c of a diameter
substantially equal to that of the gas discharge hole 301a, and the
cylindrical, expanded part 244b is provided with a large hole 244d
of a diameter greater than that of the small hole 244c.
The small hole 244c has a tapered lower end part 244e expanding
toward the lower open end thereof on the side of the gas discharge
hole 301a. The tapered end part 244e does not have any edges and
has a smooth surface.
The step 244f can be brought into contact with the shoulder 302b to
position the insulating member 244 longitudinally on the cooling
plate 302.
A part of the sidewall of the gas discharge hole 302a between the
shoulder 302b and the upper open end on the side of the space 134
is not finished by a plasma-proofing process, because fine
irregularities are formed in the sidewall of the gas discharge hole
302a if the same sidewall is finished by a plasma-proofing process,
such as anodic oxidation process, and the closeness of contact
between the sidewall of the gas discharge hole 302a and the outer
surface of the cylindrical expanded part 244b of the insulating
member 244 is deteriorated. Thus, the outer surface of the
cylindrical, expanded part 244b of the insulating member 244 is in
close contact with the sidewall of the gas discharge hole 302a.
Consequently, the plasma is unable to infiltrate into gaps between
the sidewalls of the gas discharge holes 302a and the insulating
members 244.
In the conventional etching system of this type, a silicon
electrode and a cooling plate are provided with gas discharge
holes, and any members corresponding to the insulating members 244
are not used. Therefore, the gas discharge holes of the cooling
plate are damaged by a plasma produced in a processing chamber 102
and the cooling plate must be changed periodically. Since the
insulating members 244 are fitted in the gas discharge holes 302a
in the etching system in this embodiment, the etching of the
sidewalls of the gas discharge holes 302a by the plasma produced in
the processing chamber 102 can be prevented. Therefore, it is
necessary to change only the insulating members 244 when necessary
and the cooling plate 302 does not need to be changed periodically.
Since the lower end parts of the small holes 244c are tapered to
form the tapered lower end parts 244e, the sidewalls of the small
holes 244c are not etched quickly, and hence insulating member
changing period at which the insulating members 244 are changed can
be extended.
The insulating members 244 fitted in the gas discharge holes 302a
may be of a shape other than that shown in FIGS. 6 and 7, provided
that the insulating members are able to cover the sidewalls of the
gas discharge holes 302a.
Although the preferred embodiments of the present invention have
been described with reference to the accompanying drawings, the
present invention is not limited thereto in its practical
application. It is obvious to those skilled in the art that many
changes and variations are possible without departing from the
technical scope of the present invention.
Although the insulating members are fitted in the gas discharge
holes in the foregoing embodiment, the present invention is not
limited thereto; each of the insulating member may be provided with
an expansion extending over the rim of the opening of the gas
discharge hole on the side of the processing chamber to cover edges
formed in the open end of the gas discharge hole.
Although the insulating members are pressed into the gas discharge
holes in the foregoing embodiment, an internal thread
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