U.S. patent application number 12/365385 was filed with the patent office on 2009-08-13 for mounting stage and plasma processing apparatus.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. Invention is credited to Masakazu Higuma, Shinji Himori, Yasuharu Sasaki.
Application Number | 20090199967 12/365385 |
Document ID | / |
Family ID | 40937878 |
Filed Date | 2009-08-13 |
United States Patent
Application |
20090199967 |
Kind Code |
A1 |
Himori; Shinji ; et
al. |
August 13, 2009 |
MOUNTING STAGE AND PLASMA PROCESSING APPARATUS
Abstract
A mounting stage for a plasma processing apparatus that can
prevent degradation of an insulating film in a semiconductor device
on a substrate. A conductor member is connected to a
radio-frequency power source for producing plasma. A dielectric
layer is buried in a central portion of an upper surface of the
conductor member. An electrostatic chuck is mounted on the
dielectric layer. The electrostatic chuck has an electrode film
that satisfies the following condition: .delta./z.gtoreq.85 where
.delta.=(.rho..sub.v/(.mu..pi.f)).sup.1/2 where z is the thickness
of the electrode film, .delta. is the skin depth of the electrode
film with respect to radio-frequency electrical power supplied from
the radio-frequency power source, f is the frequency of the
radio-frequency electrical power, .pi. is the ratio of a
circumference of a circle to its diameter, .mu. is the magnetic
permeability of the electrode film, and .rho..sub.v is the specific
resistance of the electrode film.
Inventors: |
Himori; Shinji;
(Nirasaki-shi, JP) ; Sasaki; Yasuharu;
(Nirasaki-shi, JP) ; Higuma; Masakazu;
(Nirasaki-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
TOKYO ELECTRON LIMITED
Tokyo
JP
|
Family ID: |
40937878 |
Appl. No.: |
12/365385 |
Filed: |
February 4, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61048366 |
Apr 28, 2008 |
|
|
|
Current U.S.
Class: |
156/345.48 ;
156/345.51 |
Current CPC
Class: |
H01J 37/32091 20130101;
H01J 37/20 20130101; H01L 21/6833 20130101; H01J 2237/0209
20130101; H02N 13/00 20130101 |
Class at
Publication: |
156/345.48 ;
156/345.51 |
International
Class: |
C23F 1/08 20060101
C23F001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2008 |
JP |
2008-029348 |
Claims
1. A mounting stage for a plasma processing apparatus on which a
substrate is mounted, comprising: a conductor member connected to a
radio-frequency power source for producing plasma; a dielectric
layer buried in a central portion of an upper surface of said
conductor member; and an electrostatic chuck mounted on said
dielectric layer, wherein said electrostatic chuck is connected to
a high-voltage direct current power source and comprises an
electrode film that satisfies the following condition:
.delta./z.gtoreq.85 where .delta.=(.rho..sub.v/(.mu..pi.f)).sup.1/2
where z is a thickness of the electrode film, .delta. is a skin
depth of the electrode film with respect to radio-frequency
electrical power supplied from the radio-frequency power source, f
is a frequency of the radio-frequency electrical power supplied
from the radio-frequency power source, .pi. is a ratio of a
circumference of a circle to its diameter, .mu. is a magnetic
permeability of the electrode film, and .rho..sub.v is a specific
resistance of the electrode film.
2. A mounting stage for a plasma processing apparatus on which a
substrate is mounted, comprising: a conductor member connected to a
radio-frequency power source for attracting ions; a dielectric
layer buried in a central portion of an upper surface of said
conductor member; and an electrostatic chuck mounted on said
dielectric layer, wherein said electrostatic chuck is connected to
a high-voltage direct current power source and comprises an
electrode film that satisfies the following condition:
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature. where
.rho..sub.s is a surface resistivity of the electrode film.
3. A mounting stage for a plasma processing apparatus on which a
substrate is mounted, comprising: a conductor member connected to a
radio-frequency power source for producing plasma and a
radio-frequency power source for attracting ions; a dielectric
layer buried in a central portion of an upper surface of said
conductor member; and an electrostatic chuck mounted on said
dielectric layer, wherein said electrostatic chuck is connected to
a high-voltage direct current power source and comprises an
electrode film that satisfies the following conditions:
.delta./z.gtoreq.85 and
.rho..sub.5.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature. where
.delta.=(.rho..sub.v/.mu..pi.f)).sup.1/2 where z is a thickness of
the electrode film, .delta. is a skin depth of the electrode film
with respect to radio-frequency electrical power supplied from the
radio-frequency power source for producing plasma, f is a frequency
of the radio-frequency electrical power supplied from the
radio-frequency power source for producing plasma, .pi. is a ratio
of a circumference of a circle to its diameter, .mu. is a magnetic
permeability of the electrode film, .rho..sub.v is a specific
resistance of the electrode film, and .rho..sub.s is a surface
resistivity of the electrode film.
4. A mounting stage for a plasma processing apparatus on which a
substrate is mounted, comprising: a conductor member connected to a
radio-frequency power source for producing plasma and a
radio-frequency power source for attracting ions; a dielectric
layer buried in a central portion of an upper surface of said
conductor member; and an electrostatic chuck mounted on said
dielectric layer, wherein said electrostatic chuck is connected to
a high-voltage direct current power source and comprises an
electrode film that satisfies the following conditions: 115
.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA.-
/.quadrature. where .rho..sub.s is a surface resistivity of the
electrode film.
5. A mounting stage for a plasma processing apparatus as claimed in
claim 2, wherein the surface resistivity .rho..sub.s is not more
than 304.OMEGA./.quadrature..
6. A mounting stage for a plasma processing apparatus as claimed in
claim 1, wherein the electrode film is formed by one of thermal
spraying, sintering and coating, and the specific resistance of the
electrode film is 1.0.times.10.sup.-2 .OMEGA.cm to
1.0.times.10.sup.3 .OMEGA.cm.
7. A mounting stage for a plasma processing apparatus as claimed in
claim 1, wherein the electrode film is formed by one of CVD, PVD,
and liquid deposition, a thickness of the electrode film is not
more than 10 .mu.m, and the specific resistance of the electrode
film is not more than 1.0.times.10.sup.2 .OMEGA.cm.
8. A mounting stage for a plasma processing apparatus as claimed in
claim 1, wherein a frequency of radio-frequency electrical power
supplied from the radio-frequency power source for producing plasma
is not less than 27 MHz.
9. A mounting stage for a plasma processing apparatus as claimed in
claim 2, wherein a frequency of radio-frequency electrical power
supplied from the radio-frequency power source for attracting ions
is not more than 27 MHz.
10. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
producing plasma, a dielectric layer buried in a central portion of
an upper surface of the conductor member, and an electrostatic
chuck mounted on the dielectric layer, the electrostatic chuck has
an electrode film connected to a high-voltage direct current power
source, and the substrate satisfies the following condition:
.delta..sub.w/z.sub.w.gtoreq.13 where
.delta..sub.w=(.rho..sub.vw/(.mu..sub.w.pi.f)).sup.1/2 where
z.sub.w is a thickness of the substrate, .delta..sub.w is a skin
depth of the substrate with respect to radio-frequency electrical
power supplied from the radio-frequency power source, f is a
frequency of the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu..sub.w is a magnetic permeability of
the substrate, and .rho..sub.vw is a specific resistance of the
substrate.
11. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
producing plasma, a dielectric layer buried in a central portion of
an upper surface of the conductor member, and an electrostatic
chuck mounted on the dielectric layer, the electrostatic chuck has
an electrode film connected to a high-voltage direct current power
source, and the substrate satisfies the following condition:
.rho..sub.sw.gtoreq.52.OMEGA./.quadrature. where .rho..sub.sw is a
surface resistivity of the substrate.
12. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
producing plasma, a dielectric layer buried in a central portion of
an upper surface of the conductor member, and an electrostatic
chuck mounted on the dielectric layer, the electrostatic chuck has
an electrode film connected to a high-voltage direct current power
source, and the substrate satisfies the following condition:
.rho..sub.vw.gtoreq.4 .OMEGA.cm where .rho..sub.vw is a specific
resistance of the substrate.
13. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
producing plasma, a dielectric layer buried in a central portion of
an upper surface of the conductor member, and an electrostatic
chuck mounted on the dielectric layer, the electrostatic chuck has
an electrode film connected to a high-voltage direct current power
source, and a wiring film on the substrate satisfies the following
condition: .delta..sub.1/z.sub.1.gtoreq.13 where
.delta..sub.1=(.rho..sub.v1/(.mu..sub.1.pi.f)).sup.1/2 where
z.sub.1 is a thickness of the wiring film, .delta..sub.1 is a skin
depth of the wiring film with respect to radio-frequency electrical
power supplied from the radio-frequency power source, f is a
frequency of the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu..sub.1 is a magnetic permeability of
the wiring film, and .rho..sub.v1 is a specific resistance of the
wiring film.
14. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
producing plasma, a dielectric layer buried in a central portion of
an upper surface of the conductor member, and an electrostatic
chuck mounted on the dielectric layer, the electrostatic chuck has
an electrode film connected to a high-voltage direct current power
source, and a wiring film on the substrate satisfies the following
condition: .rho..sub.s1.gtoreq.52 .OMEGA./.quadrature. where
.rho..sub.s1 is a surface resistivity of the wiring film.
15. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
producing plasma, a dielectric layer buried in a central portion of
an upper surface of the conductor member, and an electrostatic
chuck mounted on the dielectric layer, the electrostatic chuck is
connected to a high-voltage direct current power source and has an
electrode film that satisfies the following condition:
.delta./z.gtoreq.85 where .delta.=(.rho..sub.v/(.mu..pi.f)).sup.1/2
where z is a thickness of the electrode film, .delta. is a skin
depth of the electrode film with respect to radio-frequency
electrical power supplied from the radio-frequency power source, f
is a frequency of the radio-frequency electrical power supplied
from the radio-frequency power source, .pi. is a ratio of a
circumference of a circle to its diameter, .mu. is a magnetic
permeability of the electrode film, and .rho..sub.v is a specific
resistance of the electrode film.
16. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
attracting ions, a dielectric layer buried in a central portion of
an upper surface of the conductor member, and an electrostatic
chuck mounted on the dielectric layer, the electrostatic chuck is
connected to a high-voltage direct current power source and has an
electrode film that satisfies the following condition:
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature. where
.rho..sub.s is a surface resistivity of the electrode film.
17. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
producing plasma and a radio-frequency power source for attracting
ions, a dielectric layer buried In a central portion of an upper
surface of the conductor member, and an electrostatic chuck mounted
on the dielectric layer, the electrostatic chuck is connected to a
high-voltage direct current power source and has an electrode film
that satisfies the following conditions: .delta./z.gtoreq.85 and
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature. where
.delta.=(.rho..sub.v/(.mu..pi.f)).sup.1/2 where z is a thickness of
the electrode film, .delta. is a skin depth of the electrode film
with respect to radio-frequency electrical power supplied from the
radio-frequency power source for producing plasma, f is a frequency
of the radio-frequency electrical power supplied from the
radio-frequency power source for producing plasma, .pi. is a ratio
of a circumference of a circle to its diameter, .mu. is a magnetic
permeability of the electrode film, .rho..sub.v is a specific
resistance of the electrode film, and .rho..sub.s is a surface
resistivity of the electrode film.
18. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source for
producing plasma and a radio-frequency power source for attracting
ions, a dielectric layer buried in a central portion of an upper
surface of the conductor member, and an electrostatic chuck mounted
on the dielectric layer, the electrostatic chuck is connected to a
high-voltage direct current power source and has an electrode film
that satisfies the following condition:
115.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OME-
GA./.quadrature. where .rho..sub.s is a surface resistivity of the
electrode film.
19. A mounting stage for a plasma processing apparatus on which a
substrate is mounted, comprising: a conductor member connected to a
radio-frequency power source; a dielectric layer buried in a
central portion of an upper surface of said conductor member; and
an electrostatic chuck mounted on said dielectric layer, wherein
said electrostatic chuck is connected to a high-voltage direct
current power source and includes an electrode film for which at
least one of an upper limit value and a lower limit value of a
surface resistivity is set, and the electrode film is formed on an
upper surface or a lower surface of a plate-shaped base material
comprising a dielectric member prepared/formed in advance, and
coated with an insulating material after the electrode film is
formed.
20. A mounting stage for a plasma processing apparatus as claimed
in claim 19, wherein the electrode film is formed by thermal
spraying, coating, thin-film formation, and attachment of a
conductive film.
21. A mounting stage for a plasma processing apparatus as claimed
in claim 20, wherein the thin-film formation is one of CVD, PVD,
and liquid deposition.
22. A mounting stage for a plasma processing apparatus as claimed
in claim 19, wherein the insulating material is formed by one of
sintering, thermal spraying, and attachment of an insulating
film.
23. A mounting stage for a plasma processing apparatus on which a
substrate is mounted, comprising: a conductor member connected to a
radio-frequency power source; a dielectric layer buried in a
central portion of an upper surface of said conductor member; and
an electrostatic chuck mounted on said dielectric layer, wherein
said electrostatic chuck is connected to a high-voltage direct
current power source, includes an electrode film for which at least
one of an upper limit value and a lower limit value of a surface
resistivity is set, and further has at least two conductive members
having one end thereof being in contact with the electrode film and
the other end thereof being exposed from a surface of said
electrostatic chuck.
24. A mounting stage for a plasma processing apparatus as claimed
in claim 23, wherein at least one of the two conductive members is
disposed in a central portion of said electrostatic chuck.
25. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source, a
dielectric layer buried in a central portion of an upper surface of
the conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck is connected to a
high-voltage direct current power source and includes an electrode
film for which at least one of an upper limit value and a lower
limit value of a surface resistivity is set, and the electrode film
is formed on an upper surface or a lower surface of a plate-shaped
base material comprising a dielectric member prepared/formed in
advance, and coated with an insulating material after the electrode
film is formed.
26. A plasma processing apparatus comprising: a mounting stage on
which a substrate is mounted, wherein said mounting stage comprises
a conductor member connected to a radio-frequency power source, a
dielectric layer buried in a control portion of an upper surface of
the conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck is connected to a
high-power direct current power source and includes an electrode
film for which at least one of an upper limit value and a lower
limit value of a surface resistivity is set, and further has at
least two conductive members having one end thereof being in
contact with the electrode film and the other end thereof exposed
from a surface of the electrostatic chuck.
27. A plasma processing apparatus comprising: a mounting stage for
the plasma processing apparatus as claimed in claim 1, wherein the
substrate mounted on said mounting stage satisfies the following
condition: .delta..sub.w/z.sub.w.gtoreq.13 where
.delta..sub.w=(.rho..sub.vw/(.mu..sub.w.pi.f)).sup.1/2 where
z.sub.w is a thickness of the substrate, .delta..sub.w is a skin
depth of the substrate with respect to radio-frequency electrical
power supplied from the radio-frequency power source, f is a
frequency of the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu..sub.w is a magnetic permeability of
the substrate, and .rho..sub.vw is a specific resistance of the
substrate.
28. A plasma processing apparatus comprising: a mounting stage for
the plasma processing apparatus as claimed in claim 1, wherein the
substrate mounted on said mounting stage satisfies the following
condition: .rho..sub.sw.gtoreq.52 .OMEGA./.quadrature. where
.rho..sub.sw is a surface resistivity of the substrate.
29. A plasma processing apparatus comprising: a mounting stage for
the plasma processing apparatus as claimed in claim 1, wherein the
substrate mounted on said mounting stage satisfies the following
condition: .rho..sub.vw.gtoreq.4 .OMEGA.cm where .rho..sub.vw is a
specific resistance of the substrate.
30. A plasma processing apparatus comprising: a mounting stage for
the plasma processing apparatus as claimed in claim 1, wherein a
wiring film on the substrate mounted on said mounting stage
satisfies the following condition: .delta..sub.1/z.sub.1.gtoreq.13
where .delta..sub.1=(.rho..sub.v1/(.mu..sub.1.pi.f)).sup.1/2 where
z.sub.1 is a thickness of the wiring film, .delta..sub.1 is a skin
depth of the wiring film with respect to radio-frequency electrical
power supplied from the radio-frequency power source, f is a
frequency of the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu..sub.1 is a magnetic permeability of
the wiring film, and .rho..sub.v1 is a specific resistance of the
wiring film.
31. A plasma processing apparatus comprising: a mounting stage for
the plasma processing apparatus as claimed in claim 1, wherein a
wiring film on the substrate mounted on said mounting stage
satisfies the following condition: .rho..sub.s1.gtoreq.52
.OMEGA./.quadrature. where .rho..sub.s1 is a surface resistivity of
the wiring film.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a mounting stage on which a
substrate subjected to plasma processing is mounted, and a plasma
processing apparatus having the mounting stage, and in particular
to a mounting stage in which a dielectric layer is buried.
[0003] 2. Description of the Related Art
[0004] In a process of manufacturing a semiconductor device, a
semiconductor wafer (hereinafter referred to merely as a "wafer")
is subjected to plasma processing such as dry etching or ashing
using plasma produced from a process gas. In a plasma processing
apparatus that carries out the plasma processing, for example, a
pair of upper and lower parallel plate electrodes are disposed in a
manner opposed to each other, and radio-frequency electrical power
is applied between the opposing electrodes, whereby plasma is
produced from a process gas. When the plasma processing is to be
carried out, a wafer is mounted on the lower electrode as a
mounting stage.
[0005] In recent years, there have been many cases where plasma
with low ion energy and high electron density is used for the
plasma processing, and accordingly, the frequency of
radio-frequency electrical power applied between electrodes is very
high, for example, 100 MHz, as compared with the frequency of
conventionally applied radio-frequency electrical power (for
example, about more than a dozen MHz). However, it has been found
that if the frequency of radio-frequency electrical power to be
applied is increased, the intensity of an electric field increases
in a central portion of the surface of an electrode, that is, a
space facing a central portion of a wafer, and on the other hand,
the intensity of the electric field decreases in a space facing a
peripheral edge portion of the surface of the electrode. Thus, if
the distribution of the intensities of the electric field becomes
nonuniform, the electron densities of produced plasma also become
nonuniform. For this reason, the etching speed varies according to
the position of a wafer in the case of, for example, dry etching
using ions, and it is thus difficult to ensure the over-surface
uniformity in the dry etching.
[0006] To cope with this, there has been proposed a plasma
processing apparatus in which a dielectric layer such as ceramics
is buried in a central portion of a surface facing a lower
electrode (mounting stage) so as to make the intensity distribution
of an electric field uniform and improve the over-surface
uniformity in plasma processing (see, for example, Japanese
Laid-Open Patent Publication (Kokai) No. 2004-363552 (paragraphs 84
and 85 on page 15)).
[0007] As shown in FIG. 15A, in a plasma processing apparatus 140,
when radio-frequency electrical power is supplied from a
radio-frequency power source 142 to a lower electrode 141, the
radio-frequency electrical current that passes through a surface of
the lower electrode 141 to reach an upper portion of the lower
electrode 141 due to a skin effect goes toward a central portion of
a wafer W along a surface thereof, while a part of the
radio-frequency electrical current leaks from the central portion
of the surface of the wafer W toward the lower electrode 141 and
then flows through the interior of the lower electrode 141 toward
the outside. Here, in a part of the lower electrode 141 where a
dielectric layer 143 is buried, the radio-frequency electrical
current can fall down deeper than in other parts, and thus TM mode
hollow cylindrical resonance occurs in the central portion of the
lower electrode 141. As a result, the intensity of the electric
field facing the central portion of the wafer W can be reduced, so
that the intensity distribution of the electric field facing the
wafer W can be made uniform.
[0008] Because plasma processing is carried out in a
pressure-reduced atmosphere in many cases, an electrostatic chuck
144 is used so as to fix the wafer W in the plasma processing
apparatus 140 as shown in FIG. 15B. In the electrostatic chuck 144,
a conductive electrode film 145 is sandwiched between a lower
member and an upper member made of dielectric materials such as
alumina. In plasma processing, high-voltage DC power is supplied
from a high-voltage DC power source 146 to the electrode film 145,
so that the wafer W is electrostatically attracted and fixed due to
a Coulomb force produced on a surface of the upper member of the
electrostatic chuck 144.
[0009] While the component parts of the plasma processing apparatus
140 are thought to constitute an electric circuit associated with
radio-frequency electrical current, the wafer W is also thought to
be a constituent element of the electric circuit because the wafer
W is comprised of a semiconductor such as silicon. When the wafer W
is electrostatically attracted to the electrostatic chuck 144, the
wafer W becomes parallel to the electrode film 145, and hence the
wafer W and the electrode film 145 are thought to correspond to
resistances disposed parallel in the electric circuit.
[0010] Therefore, the value of radio-frequency electric current
flowing through the wafer W depends on the balance between the
resistance value of the wafer W and the resistance value of the
electrode film 145. For example, there has been the problem that if
the resistance value of the electrode film 145 is extremely high,
excessive radio-frequency electric current flows to the wafer W,
and at this time, a gate oxide film in a semiconductor device on
the wafer W degrades due to charge-up.
[0011] Also, if the resistance value of the electrode film 145 is
extremely small, radio-frequency electric current that leaks from
the central portion of the surface of the wafer W toward the lower
electrode 141 tends to flow through the electrode film 145, and
hence the radio-frequency electric current cannot fall down deep in
the central portion of the surface of the wafer W. As a result, TM
mode hollow cylindrical resonance cannot be produced, and thus the
intensity distribution of the electric field becomes nonuniform,
and the electron density of plasma becomes high in the space facing
the central portion of the wafer W. For this reason, galvanic
electric current flowing from the central portion to the peripheral
edge portion of the wafer W is produced. At this time as well, the
gate oxide film in the semiconductor device on the wafer W degrades
due to charge-up.
[0012] In order to prevent the charge-up of the gate oxide film, it
is necessary to limit the range of the resistance values of the
electrode film 145, that is, it is necessary to manage the
resistance value of the electrode film 145. In general, however,
because the electrode film 145 of the electrostatic chuck 144 is
sintered while being supported from both sides thereof between the
lower member and the upper member, there has been the problem that
in a process of manufacturing the electrostatic chuck 144 and after
the electrostatic chuck 144 is manufactured, the resistance value
of the electrode film 145 cannot be measured, and thus the
resistance value of the electrode film 145 cannot be managed.
SUMMARY OF THE INVENTION
[0013] The present invention provides a mounting stage and a plasma
processing apparatus that can prevent degradation of an insulating
film in a semiconductor device on a substrate.
[0014] The present invention also provides a mounting stage and a
plasma processing apparatus that can manage the resistance value of
an included electrode film.
[0015] Accordingly, in a first aspect of the present invention,
there is provided a mounting stage for a plasma processing
apparatus on which a substrate is mounted, comprising a conductor
member connected to a radio-frequency power source for producing
plasma, a dielectric layer buried in a central portion of an upper
surface of the conductor member, and an electrostatic chuck mounted
on the dielectric layer, wherein the electrostatic chuck is
connected to a high-voltage direct current power source and
comprises an electrode film that satisfies the following condition:
.delta./z.gtoreq.85, where
.delta.=(.rho..sub.v/(.mu..pi.f)).sup.1/2 and where z is a
thickness of the electrode film, .delta. is a skin depth of the
electrode film with respect to radio-frequency electrical power
supplied from the radio-frequency power source, f is a frequency of
the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu. is a magnetic permeability of the
electrode film, and .rho..sub.v is a specific resistance of the
electrode film.
[0016] According to the first aspect of the present invention,
there is provided the electrostatic chuck having the electrode film
that satisfies the condition ".delta./z.gtoreq.85". The skin depth
.delta. is a thickness with which the intensity of an electric
field decreases by 1/e in the electrode film. The greater the skin
depth .delta. is, the easier it becomes for the electric field to
pass through the electrode film, and hence the easier it becomes
for radio-frequency electric current to pass through the electrode
film in the direction of thickness and fall down deep. Thus, if
.delta./z.gtoreq.85, the major portion of radio-frequency electric
current can pass through the electrode film in the direction of
thickness and fall down deep toward the dielectric layer without
flowing in the electrode film. As a result, TM mode hollow
cylindrical resonance is produced, so that the distribution of
intensities of the electric field in a space facing the substrate
can be made uniform, and galvanic electric current can be prevented
from being produced in the substrate. This prevents degradation of
an insulating film in a semiconductor device on the substrate and
also makes it possible to carry out plasma processing uniformly
over the surface of the substrate.
[0017] Accordingly, in a second aspect of the present invention,
there is provided a mounting stage for a plasma processing
apparatus on which a substrate is mounted, comprising a conductor
member connected to a radio-frequency power source for attracting
ions, a dielectric layer buried in a central portion of an upper
surface of the conductor member, and an electrostatic chuck mounted
on the dielectric layer, wherein the electrostatic chuck is
connected to a high-voltage direct current power source and
comprises an electrode film that satisfies the following condition:
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature., where
.rho..sub.s is a surface resistivity of the electrode film.
[0018] According to the second aspect of the present invention,
there is provided the electrostatic chuck having the electrode film
that satisfies the condition
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.". The
smaller the surface resistivity of the electrode film is, the
easier it becomes for radio-frequency electric current to flow in
the electrode film. Thus, if
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.,
excessive radio-frequency electric current can be prevented from
flowing to the substrate. This prevents degradation of an
insulating film in a semiconductor device on the substrate.
[0019] Accordingly, in a third aspect of the present invention,
there is provided a mounting stage for a plasma processing
apparatus on which a substrate is mounted, comprising a conductor
member connected to a radio-frequency power source for producing
plasma and a radio-frequency power source for attracting ions, a
dielectric layer buried in a central portion of an upper surface of
the conductor member, and an electrostatic chuck mounted on the
dielectric layer, wherein the electrostatic chuck is connected to a
high-voltage direct current power source and comprises an electrode
film that satisfies the following conditions: .delta./z.gtoreq.85
and .rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.,
where .delta.=(.rho..sub.v/.mu..pi.f)).sup.1/2 and where z is a
thickness of the electrode film, .delta. is a skin depth of the
electrode film with respect to radio-frequency electrical power
supplied from the radio-frequency power source for producing
plasma, f is a frequency of the radio-frequency electrical power
supplied from the radio-frequency power source for producing
plasma, .pi. is a ratio of a circumference of a circle to its
diameter, .mu. is a magnetic permeability of the electrode film,
.rho..sub.v is a specific resistance of the electrode film, and
.rho..sub.s is a surface resistivity of the electrode film.
[0020] According to the third aspect of the present invention,
there is provided the electrostatic chuck having the electrode film
that satisfies the condition that ".delta./z.gtoreq.85" and the
condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.". The
greater the skin depth .delta. is, the easier it becomes for an
electric field to pass through the electrode film, and hence the
easier it becomes for radio-frequency electric current to pass
through the electrode film in the direction of thickness and fall
down deep. Also, the smaller the surface resistivity of the
electrode film is, the easier it becomes for radio-frequency
electric current to flow in the electrode film. Thus, if
.delta./z.gtoreq.85 and
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature., the
major portion of radio frequency electronic current can pass
through the electrode film in the direction of thickness and fall
dawn deep toward the dielectric layer without flowing in the
electrode film. As a result, TM mode hollow cylindrical resonance
is produced, so that the distribution of intensities of the
electric field in a space facing the substrate can be made uniform,
thus preventing galvanic electric current from being produced in
the substrate and preventing excessive radio-frequency electric
current from flowing to the substrate. This prevents degradation of
an insulating film in a semiconductor device on the substrate.
[0021] Accordingly, in a fourth aspect of the present invention,
there is provided a mounting stage for a plasma processing
apparatus on which a substrate is mounted, comprising a conductor
member connected to a radio-frequency power source for producing
plasma and a radio-frequency power source for attracting ions, a
dielectric layer buried in a central portion of an upper surface of
the conductor member, and an electrostatic chuck mounted on the
dielectric layer, wherein the electrostatic chuck is connected to a
high-voltage direct current power source and comprises an electrode
film that satisfies the following conditions:
115.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OME-
GA./.quadrature., where .rho..sub.s is a surface resistivity of the
electrode film.
[0022] According to the fourth aspect of the present invention,
there is provided the electrostatic chuck having the electrode film
that satisfies the condition
"115.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OM-
EGA./.quadrature.." The greater the surface resistivity of the
electrode film is, the harder it becomes for radio-frequency
electric current to flow in the electrode film, and hence the
easier it becomes for radio-frequency electric current to pass
through the electrode film in the direction of thickness and fall
down deep, and also, the smaller the surface resistivity of the
electrode film is, the easier it becomes for radio-frequency
electric current to flow to the electrode film. Thus, if
115.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.-5.OM-
EGA./.quadrature., the major portion of radio-frequency electric
current can pass through the electrode film in the direction of
thickness and fall down deep toward the dielectric layer without
flowing in the electrode film. As a result, TM mode hollow
cylindrical resonance is produced, so that the distribution of
intensities of the electric field in a space facing the substrate
can be made uniform, thus preventing galvanic electric current from
being produced in the substrate and preventing excessive
radio-frequency electric current from flowing to the substrate.
This prevents degradation of an insulating film in a semiconductor
device on the substrate.
[0023] The second aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein the
surface resistivity .rho..sub.s is not more than
304.OMEGA./.quadrature..
[0024] According to the second aspect of the present invention, it
is possible to reliably prevent excessive radio-frequency electric
current from flowing to the substrate.
[0025] The first aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein the
electrode film is formed by one of thermal spraying, sintering and
coating, and the specific resistance of the electrode film is
1.0.times.10.sup.-2 .OMEGA.cm to 1.0.times.10.sup.3 .OMEGA.cm.
[0026] According to the first aspect of the present invention, the
electrode film that satisfies the condition that
".delta./z.gtoreq.85" and the condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature." can be
fabricated with ease.
[0027] The first aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein the
electrode film is formed by one of CVD, PVD, and liquid deposition,
a thickness of the electrode film is not more than 10 .mu.m, and
the specific resistance of the electrode film is not more than
1.0.times.10.sup.2 .OMEGA.cm.
[0028] According to the first aspect of the present invention, the
electrode film that satisfies the condition that ".delta./z85" and
the condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature." can be
fabricated with ease.
[0029] The first aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein a
frequency of radio-frequency electrical power supplied from the
radio-frequency power source for producing plasma is not less than
27 MHz.
[0030] According to the first aspect of the present invention,
plasma with low ion energy and high electron density can be
produced.
[0031] The second aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein a
frequency of radio-frequency electrical power supplied from the
radio-frequency power source for attracting ions is not more than
27 MHz.
[0032] According to the second aspect of the present invention,
ions in plasma can be reliably attracted toward the substrate
mounted on the mounting stage.
[0033] Accordingly, in a fifth aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source for producing plasma, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck has an electrode film
connected to a high-voltage direct current power source, and the
substrate satisfies the following condition:
.delta..sub.w/z.sub.w.gtoreq.13, where
.delta..sub.w=(.rho..sub.vw/(.mu..sub.w.pi.f)).sup.1/2 and where
z.sub.w is a thickness of the substrate, .delta..sub.w is a skin
depth of the substrate with respect to radio-frequency electrical
power supplied from the radio-frequency power source, f is a
frequency of the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu..sub.w is a magnetic permeability of
the substrate, and .rho..sub.vw is a specific resistance of the
substrate.
[0034] According to the fifth aspect of the present invention, the
substrate that satisfies the condition that
".delta..sub.w/z.sub.w.gtoreq.13" is mounted on the mounting stage.
The skin depth .delta..sub.w of the substrate is a thickness with
which the intensity of an electric field decreases by 1/e in the
substrate. The greater the skin depth .delta..sub.w is, the easier
it becomes for the electric field to pass through the substrate,
and hence the easier it becomes for radio-frequency electric
current to pass through the substrate in the direction of thickness
and fall down deep. Thus, if .delta..sub.w/z.sub.w.gtoreq.13, the
major portion of radio-frequency electric current can pass through
the substrate in the direction of thickness and fall down deep
toward the dielectric layer without flowing in the substrate. As a
result, TM mode hollow cylindrical resonance is produced, so that
the distribution of intensities of the electric field in a space
facing the substrate can be made uniform, thus preventing galvanic
electric current from being produced in the substrate. This
prevents degradation of an insulating film in a semiconductor
device on the substrate.
[0035] Accordingly, in a sixth aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source for producing plasma, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck has an electrode film
connected to a high-voltage direct current power source, and the
substrate satisfies the following condition:
.rho..sub.sw.gtoreq.52.OMEGA./.quadrature., where .rho..sub.sw is a
surface resistivity of the substrate.
[0036] According to the sixth aspect of the present invention, the
substrate that satisfies the condition that
".rho..sub.sw.gtoreq.52.OMEGA./.quadrature." is mounted on the
mounting stage. The greater the surface resistivity of the
substrate is, the harder it becomes for radio-frequency electric
current to flow in the substrate, and hence the easier it becomes
for radio-frequency electric current to pass through the substrate
in the direction of thickness and fall down deep. Thus, if
.rho..sub.sw.gtoreq.52.OMEGA./.quadrature., the major portion of
radio-frequency electric current can pass through the substrate in
the direction of thickness and fall down deep toward the dielectric
layer without flowing in the substrate. As a result, TM mode hollow
cylindrical resonance is produced, so that the distribution of
intensities of the electric field in a space facing the substrate
can be made uniform, thus preventing galvanic electric current from
being produced in the substrate. This prevents degradation of an
insulating film in a semiconductor device on the substrate.
[0037] Accordingly, in a seventh aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source for producing plasma, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck has an electrode film
connected to a high-voltage direct current power source, and the
substrate satisfies the following condition: .rho..sub.vw.gtoreq.4
.OMEGA.cm, where .rho..sub.vw is a specific resistance of the
substrate.
[0038] According to the seventh aspect of the present invention,
the substrate that satisfies the condition that
".rho..sub.vw.gtoreq.4 .OMEGA.cm" is mounted on the mounting stage.
The greater the specific resistance of the substrate is, the harder
it becomes for radio-frequency electric current to flow in the
substrate, and hence the easier it becomes for radio-frequency
electric current to pass through the substrate in the direction of
thickness and fall down deep. Thus, if .rho..sub.vw.gtoreq.4
.OMEGA.cm, the major portion of radio-frequency electric current
can pass through the substrate in the direction of thickness and
fall down deep toward the dielectric layer without flowing in the
substrate. As a result, TM mode hollow cylindrical resonance is
produced, so that the distribution of intensities of an electric
field in a space facing the substrate can be made uniform, thus
preventing galvanic electric current from being produced in the
substrate. This prevents degradation of an insulating film in a
semiconductor device on the substrate.
[0039] Accordingly, in an eighth aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source for producing plasma, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck has an electrode film
connected to a high-voltage direct current power source, and a
wiring film on the substrate satisfies the following condition:
.delta..sub.1/z.sub.1>13, where
.delta..sub.1=(.rho..sub.v1/(.mu..sub.1.pi.f)).sup.1/2 and where
z.sub.1 is a thickness of the wiring film, .delta..sub.1 is a skin
depth of the wiring film with respect to radio-frequency electrical
power supplied from the radio-frequency power source, f is a
frequency of the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu..sub.1 is a magnetic permeability of
the wiring film, and .rho..sub.v1 is a specific resistance of the
wiring film.
[0040] According to the eighth aspect of the present invention, the
substrate having the wiring film that satisfies the condition that
".delta..sub.1/z.sub.1.gtoreq.13" is mounted on the mounting stage.
The skin depth .delta..sub.1 of the wiring film on the substrate is
a thickness with which the intensity of an electric field decreases
by 1/e in the wiring film. The greater the skin depth .delta..sub.1
is, the easier it becomes for an electric field to pass through the
wiring film, and hence the easier it becomes for radio-frequency
electric current to pass through the wiring film in the direction
of thickness and fall down deep. Thus, if
.delta..sub.1/z.sub.1.gtoreq.13, the major portion of
radio-frequency electric current can pass through the wiring film
in the direction of thickness and fall down deep toward the
dielectric layer without flowing in the wiring film on the
substrate. As a result, TM mode hollow cylindrical resonance is
produced, so that the distribution of intensities of the electric
field in a space facing the wiring film on the substrate can be
made uniform, thus preventing galvanic electric current from being
produced in the wiring film on the substrate. This prevents
degradation of an insulating film in a semiconductor device on the
substrate.
[0041] Accordingly, in a ninth aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source for producing plasma, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck has an electrode film
connected to a high-voltage direct current power source, and a
wiring film on the substrate satisfies the following condition:
.rho..sub.s1.gtoreq.52.OMEGA./.quadrature., where .rho..sub.s1 is a
surface resistivity of the wiring film.
[0042] According to the ninth aspect of the present invention, the
substrate having the wiring film that satisfies the condition that
".rho..sub.s1.gtoreq.52.OMEGA./.quadrature." is mounted on the
mounting stage. The greater the surface resistivity of the wiring
film on the substrate is, the harder it becomes for radio-frequency
electric current to flow in the wiring film, and hence the easier
it becomes for radio-frequency electric current to fall down deep.
Thus, if .rho..sub.s1.gtoreq.52.OMEGA./.quadrature., the major
portion of radio-frequency electric current can pass through the
wiring film in the direction of thickness and fall down deep toward
the dielectric layer without flowing in the wiring film on the
substrate. As a result, TM mode hollow cylindrical resonance is
produced, so that the distribution of intensities of the electric
field in a space facing the wiring film on the substrate can be
made uniform, thus preventing galvanic electric current from being
produced in the wiring film on the substrate. This prevents
degradation of an insulating film in a semiconductor device on the
substrate.
[0043] Accordingly, in a tenth aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source for producing plasma, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck is connected to a
high-voltage direct current power source and has an electrode film
that satisfies the following condition: .delta./z.gtoreq.=85, where
.delta.=(.rho..sub.v/(.mu..pi.f)).sup.1/2 and where z is a
thickness of the electrode film, .delta. is a skin depth of the
electrode film with respect to radio-frequency electrical power
supplied from the radio-frequency power source, f is a frequency of
the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu. is a magnetic permeability of the
electrode film, and .rho..sub.v is a specific resistance of the
electrode film.
[0044] According to the tenth aspect of the present invention,
there is provided the electrostatic chuck having the electrode film
that satisfies the condition that ".delta./z.gtoreq.85". The skin
depth .delta. is a thickness with which the intensity of an
electric field decreases by 1/e in the electrode film. The greater
the skin depth .delta. is, the easier it becomes for an electric
field to pass through the electrode film, and the easier it becomes
for radio-frequency electric current to pass through the electrode
film in the direction of thickness and fall down deep. Thus, if
.delta./z.gtoreq.85, the major portion of radio-frequency electric
current can pass through the electrode film in the direction of
thickness and fall down deep toward the dielectric layer without
flowing in the electrode film. As a result, TM mode hollow
cylindrical resonance is produced, so that the distribution of
intensities of the electric field in a space facing the substrate
can be made uniform, thus preventing galvanic electric current from
being produced in the substrate. This prevents degradation of an
insulating film in a semiconductor device on the substrate and also
makes it possible to carry out plasma processing uniformly over the
surface of the substrate.
[0045] Accordingly, in an eleventh aspect of the present invention,
there is provided A plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source for attracting ions, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck is connected to a
high-voltage direct current power source and has an electrode film
that satisfies the following condition:
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature., where
.mu..sub.s is a surface resistivity of the electrode film.
[0046] According to the eleventh aspect of the present invention,
there is provided the electrostatic chuck having the electrode film
that satisfies the condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.". The
smaller the surface resistivity of the electrode film is, the
easier it becomes for radio-frequency electric current to flow in
the electrode film. Thus, if
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.,
excessive radio-frequency electric current can be prevented from
flowing in the substrate. This prevents degradation of an
insulating film in a semiconductor device on the substrate.
[0047] Accordingly, in a twelfth aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source for producing plasma and a
radio-frequency power source for attracting ions, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck is connected to a
high-voltage direct current power source and has an electrode film
that satisfies the following conditions: .delta./z.gtoreq.85 and
.rho..sub.s=2.67.times.10.sup.5.OMEGA./.quadrature., where
.delta.=(.rho..sub.v/(.mu..pi.f)).sup.1/2 and where z is a
thickness of the electrode film, .delta. is a skin depth of the
electrode film with respect to radio-frequency electrical power
supplied from the radio-frequency power source for producing
plasma, f is a frequency of the radio-frequency electrical power
supplied from the radio-frequency power source for producing
plasma, .pi. is a ratio of a circumference of a circle to its
diameter, .mu. is a magnetic permeability of the electrode film,
.rho..sub.v is a specific resistance of the electrode film, and
.rho..sub.s is a surface resistivity of the electrode film.
[0048] According to the twelfth aspect of the present invention,
there is provided the electrostatic chuck having the electrode film
that satisfies the condition ".delta./z.gtoreq.85" and the
condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.". The
greater the skin depth .delta. is, the easier it becomes for an
electric field to pass through the electrode film, and hence the
easier it becomes for radio-frequency electric current to pass
through the electrode film in the direction of thickness and fall
down deep. Also, the smaller the surface resistivity of the
electrode film is, the easier it becomes for radio-frequency
electric current to flow in the electrode film. Thus, if
.delta./z.gtoreq.85 and
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature., the
major portion of radio-frequency electric current can pass through
the electrode film in the direction of thickness and fall down deep
toward the dielectric layer without flowing in the electrode film.
As a result, TM mode hollow cylindrical resonance is produced, so
that the distribution of intensities of the electric field in a
space facing the substrate can be made uniform, thus preventing
galvanic electric current from being produced in the substrate and
preventing excessive radio-frequency electric current from flowing
in the substrate. This prevents degradation of an insulating film
in a semiconductor device on the substrate.
[0049] Accordingly, in a thirteenth aspect of the present
invention, there is provided a plasma processing apparatus
comprising a mounting stage on which a substrate is mounted,
wherein the mounting stage comprises a conductor member connected
to a radio-frequency power source for producing plasma and a
radio-frequency power source for attracting ions, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, the electrostatic chuck is connected to a
high-voltage direct current power source and has an electrode film
that satisfies the following condition: 115
.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA.-
/.quadrature., where .rho..sub.s is a surface resistivity of the
electrode film.
[0050] According to the thirteenth aspect of the present invention,
there is provided the electrostatic chuck having the electrode film
that satisfies the condition "115
.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA.-
/.quadrature.". The greater the surface resistivity of the
electrode film is, the harder it becomes for radio-frequency
electric current to flow in the electrode film, and hence the
easier it becomes for radio-frequency electric current to pass
through the electrode film in the direction of thickness and fall
down deep. Also, the smaller the surface resistivity of the
electrode film is, the easier it becomes for radio-frequency
electric current to flow in the electrode film. Thus, if 115
.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA.-
/.quadrature., the major portion of radio-frequency electric
current can pass through the electrode film in the direction of
thickness and fall down deep toward the dielectric layer without
flowing in the electrode film. As a result, TM mode hollow
cylindrical resonance is produced, so that the distribution of
intensities of an electric field in a space facing the substrate
can be made uniform, thus preventing galvanic electric current from
being produced in the substrate and preventing excessive
radio-frequency electric current from flowing in the substrate.
This prevents degradation of an insulating film in a semiconductor
device on the substrate.
[0051] Accordingly, in a fourteenth aspect of the present
invention, there is provided a mounting stage for a plasma
processing apparatus on which a substrate is mounted, comprising a
conductor member connected to a radio-frequency power source, a
dielectric layer buried in a central portion of an upper surface of
the conductor member, and an electrostatic chuck mounted on the
dielectric layer, wherein the electrostatic chuck is connected to a
high-voltage direct current power source and includes an electrode
film for which at least one of an upper limit value and a lower
limit value of a surface resistivity is set, and the electrode film
is formed on an upper surface or a lower surface of a plate-shaped
base material comprising a dielectric member prepared/formed in
advance, and coated with an insulating material after the electrode
film is formed.
[0052] According to the fourteenth aspect of the present invention,
the electrode film included in the electrostatic chuck provided in
the mounting stage exposes itself once without exception before
being covered with an insulating material in a process of
manufacturing the electrostatic chuck. This make it possible to
measure the resistance value of the electrode film and thus manage
the resistance value of the included electrode film in the process
of manufacturing the electrostatic chuck.
[0053] The fourteenth aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein the
electrode film is formed by thermal spraying, coating, thin-film
formation, and attachment of a conductive film.
[0054] According to the fourteenth aspect of the present invention,
the electrode film can be reliably formed.
[0055] The fourteenth aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein the
thin-film formation is one of CVD, PVD, and liquid deposition.
[0056] According to the fourteenth aspect of the present invention,
the electrode film can be reliably and easily formed of a thin
film.
[0057] The fourteenth aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein the
insulating material is formed by one of sintering, thermal
spraying, and attachment of an insulating film.
[0058] According to the fourteenth aspect of the present invention,
the insulating material film can be reliably formed.
[0059] Accordingly, in a fifteenth aspect of the present invention,
there is provided a mounting stage for a plasma processing
apparatus on which a substrate is mounted, comprising a conductor
member connected to a radio-frequency power source, a dielectric
layer buried in a central portion of an upper surface of the
conductor member, and an electrostatic chuck mounted on the
dielectric layer, wherein the electrostatic chuck is connected to a
high-voltage direct current power source, includes an electrode
film for which at least one of an upper limit value and a lower
limit value of a surface resistivity is set, and further has at
least two conductive members having one end thereof being in
contact with the electrode film and the other end thereof being
exposed from a surface of the electrostatic chuck.
[0060] According to the fifteenth aspect of the present invention,
because the electrode film included in the electrostatic chuck
provided in the mounting stage is communicated with the outside via
the at least two conductive members having one end thereof being in
contact with the electrode film and the other end thereof being
exposed from the surface of the electrostatic chuck, it is possible
to measure the resistance value of the electrode film and thus
manage the resistance value of the included electrode film after
the electrostatic chuck is manufactured.
[0061] The fifteenth aspect of the present invention can provide a
mounting stage for a plasma processing apparatus, wherein at least
one of the two conductive members is disposed in a central portion
of the electrostatic chuck.
[0062] According to the fifteenth aspect of the present invention,
the resistance value of at least the central portion of the
electrode film can be managed.
[0063] Accordingly, in a sixteenth aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage on which a substrate is mounted, wherein the
mounting stage comprises a conductor member connected to a
radio-frequency power source, a dielectric layer buried in a
central portion of an upper surface of the conductor member, and an
electrostatic chuck mounted on the dielectric layer, the
electrostatic chuck is connected to a high-voltage direct current
power source and includes an electrode film for which at least one
of an upper limit value and a lower limit value of a surface
resistivity is set, and the electrode film is formed on an upper
surface or a lower surface of a plate-shaped base material
comprising a dielectric member prepared/formed in advance, and
coated with an insulating material after the electrode film is
formed.
[0064] According to the sixteenth aspect of the present invention,
the electrode film included in the electrostatic chuck provided in
the mounting stage exposes itself once without exception before
being covered with an insulating material in a process of
manufacturing the electrostatic chuck. This make it possible to
measure the resistance value of the electrode film and thus manage
the resistance value of the included electrode film in the process
of manufacturing the electrostatic chuck.
[0065] Accordingly, in a seventeenth aspect of the present
invention, there is provided a plasma processing apparatus
comprising a mounting stage on which a substrate is mounted,
wherein the mounting stage comprises a conductor member connected
to a radio-frequency power source, a dielectric layer buried in a
central portion of an upper surface of the conductor member, and an
electrostatic chuck mounted on the dielectric layer, the
electrostatic chuck is connected to a high-power direct current
power source and includes an electrode film for which at least one
of an upper limit value and a lower limit value of a surface
resistivity is set, and further has at least two conductive members
having one end thereof being in contact with the electrode film and
the other end thereof exposed from a surface of the electrostatic
chuck.
[0066] According to the seventeenth aspect of the present
invention, because the electrode film included in the electrostatic
chuck provided in the mounting stage is communicated with the
outside via the at least two conductive members having one end
thereof being in contact with the electrode film and the other end
thereof being exposed from the surface of the electrostatic chuck,
it is possible to measure the resistance value of the electrode
film and thus manage the resistance value of the included electrode
film after the electrostatic chuck is manufactured.
[0067] Accordingly, in an eighteenth aspect of the present
invention, there is provided a plasma processing apparatus
comprising a mounting stage for the above plasma processing
apparatus, wherein the substrate mounted on the mounting stage
satisfies the following condition: .delta..sub.w/z.sub.w.gtoreq.13,
where .delta..sub.w=(.rho..sub.vw/(.mu..sub.w.pi.f)).sup.1/2 and
where z.sub.w is a thickness of the substrate, .delta..sub.w is a
skin depth of the substrate with respect to radio-frequency
electrical power supplied from the radio-frequency power source, f
is a frequency of the radio-frequency electrical power supplied
from the radio-frequency power source, .pi. is a ratio of a
circumference of a circle to its diameter, .mu..sub.w is a magnetic
permeability of the substrate, and .rho..sub.vw is a specific
resistance of the substrate.
[0068] According to the eighteenth aspect of the present invention,
the substrate that satisfies the condition that
".delta..sub.w/z.sub.w.gtoreq.13" is mounted on the mounting stage.
The skin depth .delta..sub.w of the substrate is a thickness with
which the intensity of an electric field decreases by 1/e in the
substrate. The greater the skin depth .delta..sub.w is, the easier
it becomes for an electric field to pass through the substrate, and
hence the easier it becomes for radio-frequency electric current to
pass through the substrate in the direction of thickness and fall
down deep. Thus, if .delta..sub.w/z.sub.w.gtoreq.13, the major
portion of radio-frequency electric current can pass through the
substrate in the direction of thickness and fall down deep toward
the dielectric layer without flowing in the substrate. As a result,
TM mode hollow cylindrical resonance is produced, so that the
distribution of intensities of the electric field in a space facing
the substrate can be made uniform, thus preventing galvanic
electric current from being produced in the substrate. This
prevents degradation of an insulating film in a semiconductor
device on the substrate.
[0069] Accordingly, in an nineteenth aspect of the present
invention, there is provided a plasma processing apparatus
comprising a mounting stage for the above plasma processing
apparatus, wherein the substrate mounted on the mounting stage
satisfies the following condition:
.rho..sub.sw.gtoreq.52.OMEGA./.quadrature., where .rho..sub.sw is a
surface resistivity of the substrate.
[0070] According to the nineteenth aspect of the present invention,
the substrate that satisfies the condition that
".rho..sub.sw.gtoreq.52.OMEGA./.quadrature." is mounted on the
mounting stage. The greater the surface resistivity of the
substrate is, the harder it becomes for radio-frequency electric
current to flow in the substrate, and hence the easier it becomes
for radio-frequency electric current to pass through the substrate
in the direction of thickness and fall down deep. Thus, if
.rho..sub.sw.gtoreq.52.OMEGA./.quadrature., the major portion of
radio-frequency electric current can pass through the substrate in
the direction of thickness and fall down deep toward the dielectric
layer without flowing in the substrate. As a result, TM mode hollow
cylindrical resonance is produced, so that the distribution of
intensities of an electric field in a space facing the substrate
can be made uniform, thus preventing galvanic electric current from
being produced in the substrate. This prevents degradation of an
insulating film in a semiconductor device on the substrate.
[0071] Accordingly, in an twelfth aspect of the present invention,
there is provided a plasma processing apparatus comprising a
mounting stage for the above plasma processing apparatus, wherein
the substrate mounted on the mounting stage satisfies the following
condition: .rho..sub.vw.gtoreq.4 .OMEGA.cm, where .rho..sub.vw is a
specific resistance of the substrate.
[0072] According to the twelfth aspect of the present invention,
the substrate that satisfies the condition that
".rho..sub.vw.gtoreq.4 .OMEGA.cm" is mounted on the mounting stage.
The greater the specific resistance of the substrate is, the harder
it becomes for radio-frequency electric current to flow in the
substrate, and hence the easier it becomes for radio-frequency
electric current to pass through the substrate in the direction of
thickness and fall down deep. Thus, if .rho..sub.vw.gtoreq.4
.OMEGA.cm, the major portion of radio-frequency electric current
can pass through the substrate in the direction of thickness and
fall down deep toward the dielectric layer without flowing in the
substrate. As a result, TM mode hollow cylindrical resonance is
produced, so that the distribution of intensities of an electric
field in a space facing the substrate can be made uniform, thus
preventing galvanic electric current from being produced in the
substrate. This prevents degradation of an insulating film in a
semiconductor device on the substrate.
[0073] Accordingly, in a twenty-first aspect of the present
invention, there is provided a plasma processing apparatus
comprising a mounting stage for the above plasma processing
apparatus, wherein a wiring film on the substrate mounted on the
mounting stage satisfies the following condition:
.delta..sub.1/z.sub.1.gtoreq.13, where
.delta..sub.1=(.rho..sub.v1/(.mu..sub.1.pi.f)).sup.1/2 and where
z.sub.1 is a thickness of the wiring film, .delta..sub.1 is a skin
depth of the wiring film with respect to radio-frequency electrical
power supplied from the radio-frequency power source, f is a
frequency of the radio-frequency electrical power supplied from the
radio-frequency power source, .pi. is a ratio of a circumference of
a circle to its diameter, .mu. is a magnetic permeability of the
wiring film, and .rho..sub.v1 is a specific resistance of the
wiring film.
[0074] According to the twenty-first aspect of the present
invention, the substrate having the wiring film that satisfies the
condition that ".delta..sub.1/z.sub.1.gtoreq.13" is mounted on the
mounting stage. The skin depth .delta..sub.1 of the wiring film on
the substrate is a thickness with which the intensity of an
electric field decreases by 1/e in the wiring film. The greater the
skin depth .delta..sub.1 is, the easier it becomes for an electric
field to pass through the wiring film, and hence the easier it
becomes for radio-frequency electric current to pass through the
wiring film in the direction of thickness and fall down deep. Thus,
if .delta..sub.1/z.sub.1.gtoreq.13, the major portion of
radio-frequency electric current can pass through the wiring film
in the direction of thickness and fall down deep toward the
dielectric layer without flowing in the wiring film on the
substrate. As a result, TM mode hollow cylindrical resonance is
produced, so that the distribution of intensities of the electric
field in a space facing the wiring film on the substrate can be
made uniform, thus preventing galvanic electric current from being
produced in the wiring film on the substrate. This prevents
degradation of an insulating film in a semiconductor device on the
substrate.
[0075] Accordingly, in a twenty-second aspect of the present
invention, there is provided a plasma processing apparatus
comprising: a mounting stage for the above plasma processing
apparatus, wherein a wiring film on the substrate mounted on the
mounting stage satisfies the following condition:
.rho..sub.s1.gtoreq.52.OMEGA./.quadrature., where .rho..sub.s1 is a
surface resistivity of the wiring film.
[0076] According to the twenty-second aspect of the present
invention, the substrate having the wiring film that satisfies the
condition that ".rho..sub.s1.gtoreq.52.OMEGA./.quadrature." is
mounted on the mounting stage. The greater the surface resistivity
of the wiring film on the substrate is, the harder it becomes for
radio-frequency electric current to pass through the wiring film,
and hence the easier it becomes for radio-frequency electric
current to fall down deep. Thus, if
.rho..sub.s1.gtoreq.52.OMEGA./.quadrature., the major portion of
radio-frequency electric current can pass through the wiring film
in the direction of thickness and fall down deep toward the
dielectric layer without flowing in the wiring film on the
substrate. As a result, TM mode hollow cylindrical resonance is
produced, so that the distribution of intensities of an electric
field in a space facing the wiring film on the substrate can be
made uniform, thus preventing galvanic electric current from being
produced in the wiring film on the substrate. This prevents
degradation of an insulating film in a semiconductor device on the
substrate.
[0077] The features and advantages of the invention will become
more apparent from the following detailed description taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0078] FIG. 1 is a cross-sectional view schematically showing the
construction of a plasma processing apparatus having a mounting
stage according to an embodiment of the present invention;
[0079] FIGS. 2A and 2B are views useful in explaining the case that
high-output radio-frequency electrical power is supplied from a
first radio-frequency power source in the plasma processing
apparatus in FIG. 1, in which FIG. 2A is a partial cross-sectional
view schematically showing the construction of an electrostatic
chuck and its vicinity, and FIG. 2B is a view showing an electrical
circuit comprised of the first radio-frequency power source and
others;
[0080] FIGS. 3A and 3B are views useful in explaining the case that
high-output radio-frequency electrical power is supplied from a
second radio-frequency power source in the plasma processing
apparatus in FIG. 1, in which FIG. 3A is a partial cross-sectional
view schematically showing the construction of an electrostatic
chuck and its vicinity, and FIG. 3B is a view showing an electrical
circuit comprised of the second radio-frequency power source and
others;
[0081] FIG. 4 is a graph showing the distribution of etching speeds
at which photoresists over surfaces of respective wafers are etched
in the case that a plurality of electrode films having different
values of .delta./z;
[0082] FIG. 5 is a table showing the degrees to which gate oxide
films in TEGs of respective test wafers are degraded in the case
that a plurality of electrode films having different values of
.delta./z are used;
[0083] FIG. 6 is a graph showing the relationship between the
thickness of an electrode film, which is intended to prevent the
degradation of a gate oxide film in a device having a normal
antenna ratio, and the specific resistance of the electrode
film;
[0084] FIG. 7 is a graph showing the other relationship between the
thickness of an electrode film, which is intended to prevent the
degradation of a gate oxide film of a device having a normal
antenna ratio, and the specific resistance of the electrode
film;
[0085] FIG. 8 is a graph showing the relationship between the
thickness of an electrode film, which is intended to prevent the
degradation of a gate oxide film in a specialized device, and the
specific resistance of the electrode film;
[0086] FIG. 9 is a graph showing the distribution of etching speeds
at which surfaces of a plurality of test wafers are etched in the
case that the plurality of test wafers have different specific
resistance values are used;
[0087] FIG. 10 is an enlarged cross-sectional view schematically
showing the construction of the electrostatic chuck in FIG. 1 and
its vicinity;
[0088] FIGS. 11A and 11B are enlarged cross-sectional views
schematically showing the constructions of variations of the
electrostatic chuck in FIG. 1, in which FIG. 11A shows a first
variation, and FIG. 11B shows a second variation;
[0089] FIGS. 12A and 12B are enlarged cross-sectional views
schematically showing the construction of a third variation of the
electrostatic chuck in FIG. 1, in which FIG. 12A is a
cross-sectional view, and FIG. 12B is an enlarged view of a part A
in FIG. 12A;
[0090] FIG. 13 is a plan view showing a variation of an electrode
film in FIG. 10;
[0091] FIGS. 14A and 14B are views schematically showing the
construction of a fourth variation of the electrostatic chuck in
FIG. 1, in which FIG. 14A is a rear view, and FIG. 14B is a
cross-sectional view; and
[0092] FIGS. 15A and 15B are cross-sectional views schematically
showing the construction of a plasma processing apparatus that can
improve the over-surface uniformity of conventional plasma
processing, in which FIG. 15A shows the case that there is provided
no electrostatic chuck, and FIG. 15B shows the case that there is
provided an electrostatic chuck.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0093] The present invention will now be described in detail with
reference to the drawings showing a preferred embodiment
thereof.
[0094] FIG. 1 is a cross-sectional view schematically showing the
construction of a plasma processing apparatus having a mounting
stage according to the present embodiment. The plasma processing
apparatus is constructed such as to carry out plasma etching, for
example, RIE (reactive ion etching) or ashing, on a semiconductor
wafer (substrate) having a diameter of, for example, 300 mm.
[0095] Referring to FIG. 1, the plasma processing apparatus 10 has
a processing container 11 comprised of, for example, a vacuum
chamber, a mounting stage 12 that is disposed in a central portion
of a bottom of the processing container 11, and an upper electrode
13 that is provided above the mounting stage 12 such as to face the
mounting stage 12.
[0096] The processing container 11 has a cylindrical upper chamber
11a having a small diameter, and a cylindrical lower chamber 11b
having a large diameter. The upper chamber 11a and the lower
chamber 11b communicate with each other, and the entire processing
container 11 is constructed such as to be airtight. The mounting
stage 12 and the upper electrode 13 are accommodated in the upper
chamber 11a, and a supporting case 14 that supports the mounting
stage 12 and in which piping for a cooling medium and a backside
gas is stored are accommodated in the lower chamber 11b.
[0097] An exhaust port 15 is provided in a bottom of the lower
chamber 11b, and an exhaust unit 17 is connected to the exhaust
port 15 via an exhaust pipe 16. The exhaust unit 17 has an APC
(adaptive pressure control) valve, a DP (dry pump), a TMP
(turbo-molecular pump), and so on, all of which are not shown, and
the APC valve and so on are controlled in accordance with signals
from a controller, not shown, to evacuate and maintain the whole
interior of the processing container 11 in a desired vacuum state.
On the other hand, a transfer port 18 for wafers W is provided in a
side face of the upper chamber 11a, and the transfer port 18 can be
opened and closed by a gate valve 19. The upper chamber 11a and the
lower chamber 11b are made of conductive members such as aluminum
and grounded.
[0098] The mounting stage 12 has a lower electrode 20 (conductive
member) for producing plasma, which is a stage-shaped member made
of, for example, aluminum as a conductive material, a dielectric
layer 21 that is made of, for example, ceramics as a dielectric
material and buried in a central portion of an upper surface of the
lower electrode 20 so as to make the intensity of an electric field
uniform in a processing space, described later, and an
electrostatic chuck 22 for electrostatically attracting and fixing
a wafer W on a mounting surface. The lower electrode 20, dielectric
layer 21, and electrostatic chuck 22 are laminated in this order in
the mounting stage 12. Also, the lower electrode 20 is fixed on a
supporting stage 23, which is installed on the supporting case 14,
via an insulating member 24, and is electrically levitated relative
to the processing container 11 to a sufficient degree.
[0099] A coolant flow path 25 through which a coolant is circulated
is formed in the lower electrode 20. The coolant flowing through
the coolant flow path 25 cools the lower electrode 20, and the
wafer W mounted on the mounting surface of the upper surface of the
electrostatic chuck 22 is cooled to a desired temperature.
[0100] The electrostatic chuck 22 is made of a dielectric material
and includes a conductive electrode film 37. The electrode film 37
is made of, for example, an electrode material in which molybdenum
carbide (MoC) is contained in alumina (Al.sub.2O.sub.3). A
high-voltage DC power source 42 is connected to the electrode film
37, and high-voltage DC power supplied to the electrode film 37
generates a Coulomb force between the mounting surface of the
electrostatic chuck 22 and the wafer W, so that the wafer W is
attracted to and fixed on the mounting surface of the electrostatic
chuck 22.
[0101] through holes 26 for emitting a backside gas for improving
heat transference between the mounting surface of the electrostatic
chuck 22 and a rear surface of the wafer W are opened to the
electrostatic chuck 22. The through holes 26 communicate with a gas
flow path 27 formed in the lower electrode 20 and so on, and the
backside gas such as helium (He) supplied from a gas supply unit,
not shown, is emitted through the gas flow path 27.
[0102] A first radio-frequency power source 28 (a radio-frequency
power source for producing plasma) that supplies radio-frequency
electrical power with, for example, a frequency of 27 MHz or higher
and a second radio-frequency power source 29 (a radio-frequency
power source for attracting ions) that supplies radio-frequency
electrical power with a lower frequency than the frequency of the
radio-frequency electrical power supplied from the first
radio-frequency power source 28, for example, a frequency of 27 MHz
or lower are connected to the lower electrode 20 via respective
matchers 30 and 31. The radio-frequency electrical power supplied
from the first radio-frequency power source 28 produces plasma from
a process gas, described later, and the radio-frequency electrical
power supplied from the second radio-frequency power source 29
supplies bias electrical power to the wafer W, so that ions in the
plasma are attracted to the surface of the wafer W.
[0103] A focus ring 32 is disposed at an outer edge of an upper
surface of the lower electrode 20 so as to surround the
electrostatic chuck 22. The focus ring 32 spreads the plasma wider
than a space facing the wafer W in the processing space, described
later, so as to improve the uniformity of the etching speed over
the surface of the wafer W.
[0104] A baffle plate 33 is provided on an outer side of a lower
portion of the supporting stage 23 so as to surround the supporting
stage 23. The baffle plate 33 circulates the process gas in the
upper chamber 11a to the lower chamber 11b via a gap formed between
the baffle plate 33 and a wall of the upper chamber 11a, thus
playing a role as a rectifying plate and preventing the plasma in
the processing space, described later, from leaking into the lower
chamber 11b.
[0105] The upper electrode 13 has a ceiling electrode plate 34 made
of a conductive material facing the interior of the upper chamber
11a, an electrode plate support 35 from which the ceiling electrode
plate 34 is suspended, and a buffer chamber 36 provided in the
electrode plate support 35. One end of a gas introducing pipe 38 is
connected to the buffer chamber 36, and the other end of the gas
introducing pipe 38 is connected to a process gas supply source 39.
The process gas supply source 39 has a process gas supply amount
control mechanism, not shown, and controls the amount of process
gas to be supplied. A number of gas supply holes 40 that penetrate
the ceiling electrode plate 34 and communicate the buffer chamber
36 and the interior of the upper chamber 11a together are formed in
the ceiling electrode plate 34.
[0106] In the upper electrode 13, the process gas supplied from the
process gas supply source 39 to the buffer chamber 36 is dispersed
into the upper chamber 11a via the gas supply holes 40, and the
upper electrode 13 thus acts as a showerhead supplying the process
gas. Moreover, the upper electrode 13 is fixed to a wall of the
upper chamber 13, and an electrically-conducting path is thus
formed between the upper electrode 13 and the processing container
11.
[0107] In the plasma processing apparatus 10, two multi-pole ring
magnets 41a and 41b are disposed around the upper chamber 11a and
above and below the gate valve 19. In each of the multi-pole ring
magnets 41a and 41b, a plurality of anisotropic segment columnar
magnets, not shown, are accommodated in a ring-shaped magnetic
casing, not shown, and they are arranged in the casing such that
the direction of magnetic poles of the adjacent plurality of
segment columnar magnets are opposite. Thus, a magnetic line is
formed between the adjacent segment columnar magnets, a magnetic
field is formed around the processing space located between the
upper electrode 13 and the lower electrode 20, and the plasma is
trapped in the processing space by the magnetic field. It should be
noted that the plasma processing apparatus 10 may not be provided
with the multi-pole ring magnets 41a and 41b.
[0108] In the plasma processing apparatus 10, when the wafer W is
to be subjected to the RIE or the ashing, the pressure in the
processing container 11 is adjusted to a desired vacuum state, and
then a process gas is introduced into the upper chamber 11a to
supply radio-frequency electrical power from the first
radio-frequency power source 28 and the second radio-frequency
power source 29, whereby the process gas is turned into plasma, and
ions in the plasma are attracted to the wafer W. At this time, in
order to produce plasma with low ion energy and high electron
density, it is preferred that the first radio-frequency power
source 28 supplies radio-frequency electrical power with a
frequency of 27 MHz or higher, more preferably, 40 MHz or higher,
and further, in order to reliably attract the ions in the plasma
toward the wafer W, it is preferred that the second radio-frequency
power source 29 supplies radio-frequency electrical power with a
frequency of 27 MHz or lower, more preferably, 13.56 MHz or lower.
The radio-frequency electrical power supplied from the first
radio-frequency power source 28 and the second radio-frequency
power source 29 flows through a path consisting of the lower
electrode 20, the plasma, the upper electrode 13, a wall of the
processing chamber 11, and a ground.
[0109] In the plasma processing apparatus 10, because the
radio-frequency electrical power supplied from the first
radio-frequency power source 28 has a relatively high frequency (40
MHz or higher), the intensity of the electric field in an area
facing a central portion of the wafer W tends to be high in the
processing space. In order to eliminate this tendency and make the
intensity distribution of the electric field in the processing
space uniform, the plasma processing apparatus 10 is provided with
the dielectric layer 21 of the lower electrode 20. Due to the
presence of the dielectric layer 21, the radio-frequency electrical
power supplied from the first radio-frequency power source 28 falls
down deep from the central portion of the wafer W toward the
dielectric layer 21 of the lower electrode 20. As a result, TM mode
hollow cylindrical resonance occurs in the central portion of the
lower electrode 20, so that the intensity distribution of the
electric field in the processing space is made uniform.
[0110] In the plasma processing apparatus 10, the first
radio-frequency power source 28, second radio-frequency power
source 29, dielectric layer 21, electrostatic chuck 22, electrode
film 37, wafer W, plasma PZ, and so on (FIG. 2A) constitute an
electric circuit 43 as shown in FIG. 2B. The second radio-frequency
power source 29 and so on (FIG. 3A) constitute an electric circuit
44 as shown in FIG. 3B. Because the dielectric layer 21 exists only
in the central portion of the lower electrode 20, a circuit 43a
(44a) corresponding to the central portion of the lower electrode
20 and a circuit 43b (44b) corresponding to a peripheral edge
portion of the lower electrode 20 are thought to exist in the
electric circuit 43 (44), and the circuit 43a (44a) and the circuit
43b (44b) are bridged by a resistance R.sub.W of the wafer W and a
resistance R.sub.E of the electrode film 37. When the wafer W is
mounted on the mounting surface of the electrostatic chuck 22, the
wafer W and the electrode film 37 become parallel with each other,
and hence the resistance R.sub.W of the wafer W and the resistance
R.sub.E are arranged parallel in terms of an electric circuit.
[0111] If the resistance R.sub.E of the electrode film 37 is small
in the case that high-output radio-frequency electrical power is
supplied from the first radio-frequency power source 28,
radio-frequency electrical current from the first radio-frequency
power source 28 passes through the electrostatic chuck 22 in the
direction of thickness from the central portion of the wafer W and
further flows from the central portion of the electrostatic chuck
22 to the peripheral edge portion thereof through the electrode
film 37 instead of falling down toward the dielectric layer 21. As
a result, it becomes difficult to produce an electric field
resulting from radio-frequency electrical current falling down to
the dielectric layer 21 and passing through the electrode film 37.
A description will now be given of this phenomenon.
[0112] In the present embodiment, a skin depth .delta. of the
electrode film 37 is used as an index indicative of the degree to
which the electric field passing through the electrode film 37
decreases. The skin depth .delta. is a thickness with which the
intensity of the electric field passing through the electrode film
37 decreases by 1/e. If the skin depth .delta. is large, the
electric field resists decreasing, and the electric field is apt to
pass through the electrode film 37 well, and if the skin depth
.delta. is small, the electric field is apt to decrease and resists
passing through the electrode film 37. The skin depth .delta. is
expressed by the following equation (1):
.delta.=(2.rho..sub.v/(.mu..omega.)).sup.1/2=(.rho..sub.v/(.mu..pi.f)).s-
up.1/2 (1)
where .mu. is a magnetic permeability (H/m) of the electrode film
37, .omega. is 2 .pi.f (.pi.: the ratio of the circumference of a
circle to its diameter, and f: the frequency (Hz) of
radio-frequency electrical power supplied from the first
radio-frequency power source 28), and .rho..sub.v is a specific
resistance (.OMEGA.m) of an electrode material constituting the
electrode film 37.
[0113] The electric field E formed in the electrode film 37 is
expressed by the following equation (2) using a Maxwell
equation:
E=E.sub.0 exp(-i.omega.t)exp(iz/.delta.)exp(-z/.delta.) (2)
where z is a thickness (m) of the electrode film 37, and E.sub.0 is
an intensity of the electric field incidents on the electrode film
37.
[0114] That is, the permeability (E/E.sub.0) at which the electric
field of the radio-frequency electrical power supplied from the
first radio-frequency power source 28 passes through the electrode
film 37 is proportional to "exp(-z/.delta.)" as expressed by the
following equation (3):
E/E.sub.0.varies.exp(-z/.delta.) (3)
[0115] As is obvious from the above equation (3), the closer to "0"
the value of "z/.delta." becomes, the closer to 1.0 (100%) the
permeability of the electric field becomes, and the smaller is
".delta.," the smaller is the permeability of the electric field.
Here, a low resistance R.sub.E of the electrode film 37 is nothing
else a low specific resistance .rho..sub.v of the electrode film
37, and hence if the resistance R.sub.E is small, the skin depth
.delta. expressed by ".rho..sub.v/(.mu..pi.f)).sup.1/2" is small,
and it is thus difficult to produce the electric field passing
through the electrode film 37.
[0116] If the electric field passing through the electrode film 37
is hardly produced, TM mode hollow cylindrical resonance does not
occur in the central portion of the lower electrode 20, and the
intensity of the electric field in an area facing the central
portion of the wafer W (hereinafter referred to as the "central
space") in the processing space becomes higher than the intensity
of the electric field in an area facing the peripheral edge of the
wafer W (hereinafter referred to as the "peripheral edge space") in
the processing space, and the electron density of the plasma in the
central space increases. As a result, the distribution of etching
speeds over the surface of the wafer W becomes non-uniform.
[0117] Moreover, at this time, galvanic electric current (indicated
by a dashed arrow in FIG. 2B) is produced in a circuit comprised of
a resistance R.sub.C of the plasma PZ, a sheath capacitor C.sub.P
of the plasma PZ, a capacitor C.sub.T of a gate oxide film, and a
resistance R.sub.W of the wafer W in the electric circuit 43 due to
the non-uniform distribution of electron densities of the plasma in
the processing space. When the galvanic electric current flows in
the wafer W, a gate oxide film (insulating film) in a semiconductor
device (hereinafter referred to merely as a "device") on the wafer
W is damaged and degraded due to charge-up.
[0118] To make the distribution of etching speeds over the surface
of the wafer W uniform and prevent degradation of the gate oxide
film in the device in the case that high-output radio-frequency
electrical power is supplied from the first radio-frequency power
source 28, radio-frequency electric current from the first
radio-frequency power source 28 has to be prevented from flowing
through the electrode film 37, and the radio-frequency electrical
current has to be caused to fall down deep toward the dielectric
layer 21 so as to produce an electric field passing through the
electrode film 37. To this end, ".delta./z" has to be greater than
in the above equation (3). To increase ".delta./z", it is only
necessary to increase the skin depth .delta. or decrease the
thickness "z" of the electrode film 37. Because the skin depth
.delta. is expressed by "(.rho..sub.v/(.mu..pi.f)).sup.1/2" as
described above, it is only necessary to use an electrode material
with a high specific resistance .rho..sub.vto increase the
resistance R.sub.E of the electrode film 37 in the case that the
frequency of the radio-frequency electrical power is constant. The
higher the frequency of radio-frequency electrical power, the
smaller the skin depth .delta.
(.delta..varies.(1/.omega.))=(1/2.pi.f)), and hence if the
frequency of radio-frequency electrical power is high, it is only
necessary to use an electrode material with a higher specific
resistance .rho..sub.v as a constituent material of the electrode
film 37.
[0119] Moreover, in the electric circuit 44, when high-output
radio-frequency electrical power is supplied from the second
radio-frequency power source 29, because the capacitor C.sub.T of
the dielectric layer 21 exists in the circuit 44a corresponding to
the central portion of the lower electrode 20, the radio-frequency
electrical current from the second radio-frequency power source 29
mainly flows through the circuit 44b corresponding to the
peripheral edge portion of the lower electrode 20, not through the
circuit 44a, and in the end, flows back to the circuit 44a
(indicated by a thick solid arrow in FIG. 3B). Here, if the
resistance R.sub.E of the electrode film 37 is set to be high, the
resistance R.sub.E of the electrode film 37 is higher than the
resistance R.sub.W of the wafer W, and hence the radio-frequency
electrical current flowing back to the circuit 44a flows mainly
through the wafer W, not through the electrode film 37. Thus, a
potential difference arises in the surface of the wafer W, and the
charge of the gate oxide film (insulating film) over the surface of
the wafer W becomes unbalanced. As a result, the gate oxide film in
the device on the wafer W is damaged and degraded due to
charge-up.
[0120] To prevent the degradation of the gate oxide film in the
device in the case that high-output radio-frequency electrical
power is supplied from the second radio-frequency power source 29,
it is necessary to prevent radio-frequency electric current from
the second radio-frequency power source 29 from flowing mainly
through the wafer W. To that end, it is only necessary to make the
resistance R.sub.E of the electrode film 37 small so that the
radio-frequency electrical current can flow through the electrode
film 37.
[0121] For the reasons stated above, to make the distribution of
etching speeds over the surface of the wafer W uniform in the case
that high-output radio-frequency electrical power is supplied from
the first radio-frequency power source 28, it is only necessary to
make the value of .delta./z larger than a certain value (in other
words, it is only necessary to make the resistance R.sub.E of the
electrode film 37 larger than a certain value). Moreover, to
prevent the degradation of the gate oxide film in the device in
both the case that high-output radio-frequency electrical power is
supplied from the first radio-frequency power source 28 and the
case that high-output radio-frequency electrical power is supplied
from the second radio-frequency power source 29, it is only
necessary to make the value of ".delta./z" larger than a certain
value and smaller than another certain value (in other words, it is
only necessary to make the resistance R.sub.E of the electrode film
37 larger than a certain value and make the resistance R.sub.E of
the electrode film 37 smaller than another certain value).
[0122] First, the inventors of the present invention prepared a
plurality of electrode films 37 having different values of
.delta./z (and resistance R.sub.E) so as to find a value of
.delta./z (and resistance R.sub.E) that can make the distribution
of etching speeds over the surface of the wafer W uniform. The
inventors of the present invention then carried out the ashing on
photoresists of wafers W using the respective electrode films 37 in
the plasma processing apparatus 10, observed the distribution of
etching speeds for the photoresists over the surfaces of the
respective wafers W, and graphed the observation results in FIG. 4.
As stated below, to remove the effect of the thickness of the
electrode film 37 from the resistance R.sub.E of the electrode film
37, the resistance value of the electrode film 37 was expressed by
a surface resistivity .rho..sub.s. The surface resistivity
.rho..sub.s is expressed by the following equation (4), and is a
value indicative of a resistance value per unit area and determined
by the property value (specific resistance .rho..sub.v) of an
electrode material constituting the electrode film 37 and the
thickness of the electrode film 37:
.rho..sub.s=.rho..sub.v/z (.OMEGA./.quadrature.) (4)
The values of .delta./z (and .rho..sub.s) of the electrode films 37
used here were 7518 (and 8.9.times.10.sup.5.OMEGA./.quadrature.),
6711 (and 2.67.times.10.sup.5.OMEGA./.quadrature.), 297 (and
1740.OMEGA./.quadrature.), 195 (and 750.OMEGA./.quadrature.), 124
(and 304.OMEGA./.quadrature.), 103 (and 208.OMEGA./.quadrature.),
92 (and 166.OMEGA./.quadrature.), 85 (and 115.OMEGA./.quadrature.),
and 47 (and 35.OMEGA./.quadrature.).
[0123] Moreover, in the ashing, an O.sub.2 single gas was
introduced as a process gas into the upper chamber 11a at a flow
rate of 100 sccm, the frequency of radio-frequency electrical power
supplied from the first radio-frequency power source 28 was set to
100 MHz, and the value thereof was set to 2000 W, but no
radio-frequency electrical power was supplied from the second
radio-frequency power source 29.
[0124] In the graph of FIG. 4, the abscissa indicates the distance
from the center of the wafer W, and the ordinate indicates the
etching speed (nm/sec). The broken line corresponds to the case
that .delta./z (and the surface resistivity)=47
(35.OMEGA./.quadrature.), and the other solid line corresponds to
the case that .delta./z (and the surface resistivity).gtoreq.85
(115.OMEGA./.quadrature.).
[0125] From the graph of FIG. 4, it was found that if .delta./z is
not less than 85 (.rho..sub.s is not less than
115.OMEGA./.quadrature.), the distribution of etching speeds over
the surface of the wafer W can be made substantially uniform.
[0126] Next, the inventors of the present invention prepared a
plurality of electrode films 37 having different values of
.delta./z (and resistance R.sub.E) so as to find .delta./z (and
resistance R.sub.E) that can prevent the degradation of a gate
oxide film in both the case that high-output radio-frequency
electrical power is supplied from the first radio-frequency power
source 28 and the case that high-output radio-frequency electrical
power is supplied from the second radio-frequency power source 29.
Then, the inventors of the present invention carried out the RIE or
the ashing on test wafers using the respective electrode films 37
in the plasma processing apparatus 10, observed the degradation of
gate oxide films in TEGs (Test Element Groups) of the test wafers,
and graphed the observation results in a table of FIG. 5.
[0127] In general, in the TEGs, the antenna ratio is set to 10
times or less, and to the maximum, 100 times or less, but here, to
accelerate the degradation of the gate oxide films in the TEGs,
test wafers whose antenna ratio in TEGs was set to 10000 (10 K)
times, and test wafers whose antenna ratio in TEGs was set to
100000 (100 K) times (hereinafter referred to as the "100 K test
wafers") were used. As an index of the degradation of gate oxide
films, the rate of the number of gate oxide films whose degradation
levels did not exceed a predetermined value before and after the
RIE or the ashing to the number of all the gate oxide films of the
test wafers (hereinafter referred to as the "gate oxide survival
rate (%)") was used.
[0128] With respect to a threshold value for the gate oxide
survival rate, in a normal plasma processing apparatus whose lower
electrode 20 does not have the dielectric layer 21 and uses
radio-frequency electrical power with a relatively low frequency
for producing plasma, the gate oxide film survival rate was 54%
when the RIE was carried out on the above-mentioned 100 K test
wafers, and thus a percentage of 54% was used as a threshold value
for the normal gate oxide film survival rate (hereinafter referred
to as the "normal threshold value"). It should be noted that in the
above-mentioned normal plasma processing apparatus, even when a
test wafer having TEGs with a normal antenna ratio (about 10 times)
was subjected to the RIE, degradation of a gate oxide film of the
test wafer did not occur. Moreover, when a yield required when a
specialized device is subjected to the RIE or the ashing is
converted into the gate oxide survival rate when the
above-mentioned 100 K test wafer is subjected to the RIE or the
ashing, the yield corresponds to 65%, and thus the value of 65% was
used as a threshold value for the gate oxide film survival rate in
a specialized device when the 100 K test wafer was subjected to the
RIE.
[0129] Moreover, .delta./z (and .rho..sub.s) of each electrode film
37 used here was set to be the same as .delta./z (and .rho..sub.s)
when the above described distribution of etching speeds for a
photoresist over the surface of each wafer was observed.
[0130] In the case that high-output radio-frequency electrical
power was supplied from the first radio-frequency power source 28,
an O.sub.2 single gas was introduced as a process gas into the
upper chamber 11a at a flow rate of 200 sccm, the frequency of the
radio-frequency electrical power supplied from the first
radio-frequency power source 28 was set to 100 MHz, the value
thereof was set to 2400 W, and the ashing was carried out on each
test wafer without supplying radio-frequency electrical power from
the second radio-frequency power source 29. Further, in the case
that high-output radio-frequency electrical power was supplied from
the second radio-frequency power source 29, a mixed gas of
C.sub.4F.sub.8 gas, Ar gas, and O.sub.2 gas (the flow ratio:
C.sub.4F.sub.8 gas/Ar gas/O.sub.2 gas=35/200/30 sccm) was
introduced as a process gas into the upper chamber 11a, the
frequency of the radio-frequency electrical power supplied from the
first radio-frequency power source 28 was set to 100 MHz, the value
thereof was set to 500 W, the frequency of the radio-frequency
electrical power supplied from the second radio-frequency power
source 29 was set to 3.2 MHz, the value thereof was set to 4000 W,
and the RIE was carried out on each test wafer. It should be noted
that in FIG. 5, "high-power HF" corresponds to the case that
high-output radio-frequency electrical power is supplied from the
first radio-frequency power source 28, and "high-power LF"
corresponds to the case that high-output radio-frequency electrical
power is supplied from the second radio-frequency power source
29.
[0131] The table of FIG. 5 shows plan views of test wafers which
indicate in dark and light patterns the distributions of gate oxide
films whose degradation levels did not exceed a predetermined
value, and gate oxide film survival rates under respective test
conditions. The dark-color parts in the distributions of gate oxide
films correspond to gate oxide films whose degradation levels
exceeded the predetermined value.
[0132] From the table of FIG. 5, it was found that in the case that
high-output radio-frequency electrical power is supplied from the
first radio-frequency power source 28, if .delta./z is not less
than 85 (.rho..sub.s is not less than 115.OMEGA./.quadrature.), the
gate oxide film survival rate when the 100 K test wafer is
subjected to the ashing is not less than the normal threshold value
(54%), and in the case that high-output radio-frequency electrical
power is supplied from the second radio-frequency power source 29,
if .rho..sub.s is not more than
2.67.times.10.sup.5.OMEGA./.quadrature., the gate oxide film
survival rate when the 100 K test wafer is subjected to the RIE is
not less than the normal threshold value (54%). It was thus found
that if the conditions that ".delta./z.gtoreq.85 and
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature." or the
conditions that "115
.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA.-
/.quadrature." are satisfied, the degradation of a gate oxide film
in a device having the normal antenna ratio can be prevented in
both the case that high-output radio-frequency electrical power is
supplied from the first radio-frequency power source 28 and the
case that high-output radio-frequency electrical power is supplied
from the second radio-frequency power source 29.
[0133] Moreover, from the table of FIG. 5, it was found that in the
case that high-output radio-frequency electrical power is supplied
from the first radio-frequency power source 28, if .delta./z is not
less than 85 (.rho..sub.s is not less than
115.OMEGA./.quadrature.), the gate oxide film survival rate when
the 100 K test wafer is subjected to the ashing is not less than
the specialized device threshold value (65%), and in the case that
high-output radio-frequency electrical power is supplied from the
second radio-frequency power source 29, if .rho..sub.s is not more
than 304.OMEGA./.quadrature., the gate oxide film survival rate
when the 100 K test wafer is subjected to the RIE is not less than
the specialized device threshold value (65%). It was thus found
that if the conditions that ".delta./z.gtoreq.85 and
.rho..sub.s.ltoreq.304 .OMEGA./.quadrature." or the conditions that
"115.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.304.OMEGA./.quadrature-
." are satisfied, the degradation of a gate oxide film in a
specialized device can be prevented in both the case that
high-output radio-frequency electrical power is supplied from the
first radio-frequency power source 28 and the case that high-output
radio-frequency electrical power is supplied from the second
radio-frequency power source 29.
[0134] The present invention has been developed based on the
above-described findings, and according to the present embodiment,
in the mounting stage 12 of the plasma processing apparatus 10, the
skin depth .delta. of the electrode film 37 and the thickness
thereof are set so as to satisfy the condition that
".delta./z.gtoreq.85", and the surface resistivity .rho..sub.s of
the electrode film 37 is set so as to satisfy the condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.".
Alternatively, the surface resistivity .rho..sub.s of the electrode
film 37 is set so as to satisfy the condition that
"115.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OM-
EGA./.quadrature.".
[0135] The mounting stage 12 according to the present embodiment is
provided with the electrostatic chuck 22 having the electrode film
37 that satisfies the condition ".delta./z.gtoreq.85" and the
condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.". The
greater the skin depth .delta. is, the easier it becomes for the
electric field to pass through the electrode film 37. For this
reason, high-output radio-frequency electric current from the first
radio-frequency power source 28 can easily pass through the
electrode film 37 in the direction of thickness and fall down deep
toward the dielectric layer 21, and moreover, the smaller the
surface resistivity .rho..sub.s of the electrode film 37 is, the
easier it becomes for radio-frequency electric current from the
second radio-frequency power source 29 to flow in the electrode
film 37. Therefore, if the electrode film 37 satisfies the
conditions that .delta./z.gtoreq.85 and
.rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature., the
major portion of radio-frequency electric current can pass through
the electrode film 37 in the direction of thickness and fall down
deep toward the dielectric layer 21 without flowing in the
electrode film 37. As a result, TM mode hollow cylindrical
resonance is produced in the central portion of the lower electrode
20, so that the distribution of intensities of the electric field
in the processing space can be made uniform, thus preventing
galvanic electric current from being produced in a wafer W and
preventing excessive radio-frequency electric current from flowing
in a wafer W from the second radio-frequency electrical power 20.
This prevents degradation of a gate oxide film in a device having a
normal antenna ratio on a wafer W.
[0136] Moreover, according to the mounting stage 12 of the present
embodiment, the electrode film 37 satisfies the condition that
"115.OMEGA./.quadrature..ltoreq..rho..sub.s." The higher the
surface resistivity .rho..sub.s of the electrode film 37, it
becomes more difficult for radio-frequency electric current to flow
in the electrode film 37, and hence radio-frequency electric
current from the first radio-frequency power source 28 can pass
through the electrode film 37 in the direction of thickness and
fall down deep. Thus, if the electrode film 37 satisfies the
condition that "115.OMEGA./.quadrature..ltoreq..rho..sub.s", the
major portion of radio-frequency electric current from the first
radio-frequency power source 28 can pass through the electrode film
37 in the direction of thickness and fall down deep toward the
dielectric layer 21.
[0137] In the mounting stage 12 described above, the electrode film
37 may be configured such as to satisfy the conditions that
".delta./z.gtoreq.85 and
.rho..sub.s.ltoreq.304.OMEGA./.quadrature." or the condition that
"115.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.304.OMEGA./.quadrature-
.." If the surface resistivity .rho..sub.s of the electrode film 37
is not more than 304.OMEGA./.quadrature., excessive radio-frequency
electric current can be reliably prevented flowing in a wafer W
from the second radio-frequency power source 29. As a result,
degradation of a gate oxide film in a specialized device on a wafer
W can be prevented.
[0138] The condition that ".delta./z.gtoreq.85" for preventing
degradation of a gate oxide film in a device having a normal
antenna ratio can be converted into the following equation (5):
z.ltoreq.(.rho..sub.v/(.mu..pi.f)).sup.1/2/85 (5)
Also, the condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature." for
preventing degradation of a gate oxide film in a device having a
normal antenna ratio can be converted into the following equation
(6):
z.gtoreq..rho..sub.v/(2.67.times.10.sup.5) (6)
[0139] That is, the electrode film 37 has to satisfy the above
equations (5) and (6) so as to prevent degradation of a gate oxide
film in a device having a normal antenna ratio.
[0140] FIG. 6 is a graph showing a range that satisfies the above
equations (5) and (6) when the abscissa indicates the specific
resistance of the electrode film 37, the ordinate indicates the
thickness of the electrode film 37, and only the abscissa is
logarithmically indicated. FIG. 7 is a graph showing a range that
satisfies the above equations (5) and (6) when the abscissa
indicates the specific resistance of the electrode film 37, the
ordinate indicates the thickness of the electrode film 37, and both
the abscissa and the ordinate are logarithmically indicated.
[0141] In the graphs of FIGS. 6 and 7, the solid line corresponds
to the above equation (5), and the broken line corresponds to the
above equation (6). Thus, the thickness and the specific resistance
of the electrode film 37 have to be within a range surrounded by
the solid line and the broken line.
[0142] Referring to the graph of FIG. 6, it is only necessary for
the specific resistance of the electrode film 37 to be from
1.0.times.10.sup.-2 .OMEGA.cm to 1.0.times.10.sup.3 .OMEGA.cm in
the case that the thickness of the electrode film 37 is from
several .mu.m to 110 .mu.m so that the thickness and the specific
resistance of the electrode film 37 can fall within the range
surrounded by the solid line and the broken line (corresponding to
the diagonally shaded area in FIG. 6). Also, referring to the graph
of FIG. 7, it is only necessary for the specific resistance of the
electrode film 37 to be not more than 1.0.times.10.sup.2 .OMEGA.cm
in the case that the thickness of the electrode film 37 is not more
than 10 .mu.m (corresponding to the diagonally shaded area in FIG.
7). That is, in the present embodiment, the thickness of the
electrode film 37 is set to several .mu.m to 110 .mu.m, and the
specific resistance of the electrode film 37 is set to
1.0.times.10.sup.-2 .OMEGA.cm to 1.0.times.10.sup.3 .OMEGA.cm, or
the thickness of the electrode film 37 is set to several .mu.m to
10 .mu.m or less, and the specific resistance of the electrode film
37 is set to 1.0.times.10.sup.2 .OMEGA.cm or less. For this reason,
the electrode film 37 can reliably satisfy the conditions that
".delta./z.gtoreq.85" and
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature." for
preventing degradation of a gate oxide film in a device having a
normal antenna ratio.
[0143] In the case that the thickness of the electrode film 37 is
set to several .mu.m to 110 .mu.m, and the specific resistance of
the electrode film 37 is set to 1.0.times.10.sup.-2 .OMEGA.cm to
1.0.times.10.sup.3 .OMEGA.cm, relatively large variations in
thickness and specific resistance are tolerated, and hence from the
viewpoint of the ease of manufacturing, it is preferred that the
electrode film 37 is formed by any of thermal spraying, sintering,
and coating of a conductive material (for example, screen
printing). Also, in the case that the thickness of the electrode
film 37 is set to 10 .mu.m or less, and the specific resistance of
the electrode film 37 is set to 1.0.times.10.sup.2 .OMEGA.cm or
less, a tolerated thickness corresponds to the so-called thickness
of a thin film, and hence it is preferred that the electrode film
37 is formed by a thin-film formation such as CVD, PVD, or liquid
deposition.
[0144] Moreover, the condition that ".delta./z.gtoreq.=85" for
preventing degradation of a gate oxide film in a specialized device
can be converted into the above equation (5). Also, the condition
that ".rho..sub.s.ltoreq.304.OMEGA./.quadrature." for preventing
degradation of a gate oxide film in a specialized device can be
converted into the following equation (7):
z.gtoreq..rho..sub.v/304 (7)
[0145] That is, the electrode film 37 has to satisfy the above
equations (5) and (7) so as to prevent degradation of a gate oxide
film in a specialized device.
[0146] FIG. 8 is a graph showing a range that satisfies the above
equations (5) and (7) when the abscissa indicates the specific
resistance of the electrode film 37, the ordinate indicates the
thickness of the electrode film 37, and both the abscissa and the
ordinate are logarithmically indicated.
[0147] In the graph of FIG. 8, the solid line corresponds to the
above equation (5), and the broken line corresponds to the above
equation (7). Thus, the thickness and the specific resistance of
the electrode film 37 have to be within a range surrounded by the
solid line and the broken line.
[0148] Here, referring to the graph of FIG. 8, it is only necessary
for the specific resistance of the electrode film 37 to be from
1.0.times.10.sup.-6 .OMEGA.cm to 0.1 .OMEGA.cm in the case that the
thickness of the electrode film 37 is from 1.0.times.10.sup.-3
.mu.m to 10 .mu.m so that the thickness and the specific resistance
of the electrode film 37 can be within the range surrounded by the
solid line and the broken line (corresponding to the diagonally
shaded area in FIG. 8). That is, in the present embodiment, the
thickness of the electrode film 37 may be set to
1.0.times.10.sup.-3 .mu.m to 10 .mu.m, and the specific resistance
of the electrode film 37 is set to 1.0.times.10.sup.-6 .OMEGA.cm to
0.1 .OMEGA.cm. For this reason, the electrode film 37 can satisfy
the conditions that ".delta./z.gtoreq.85" and
".rho..sub.s.ltoreq.304.OMEGA./.quadrature." for preventing
degradation of a gate oxide film in a specialized device.
[0149] Here, the tolerable ranges of both the thickness and the
specific resistance of the electrode film 37 are narrow, but a
metallic thin film such as copper or aluminum formed by PVD or the
like has a specific resistance of 1.0.times.10.sup.-6 .OMEGA.cm to
1.0.times.10.sup.-4 .OMEGA.cm and varies in thickness within the
single digits, and it is thus preferred that the electrode film 37
is comprised of a metallic thin film such as copper or aluminum
formed by PVD or the like. It should be noted that in the case that
the electrode film 37 is constructed by thermal spraying,
sintering, or the like, and the thickness thereof is set to several
.mu.m to 110 .mu.m, the specific resistance of the electrode film
37 has to be selected from a very narrow range from 0.01 .OMEGA.cm
to 10 .OMEGA.cm.
[0150] In the plasma processing apparatus 10 described above, if
the resistance R.sub.W of the wafer W is small in the case that
high-output radio-frequency electrical power is supplied from the
first radio-frequency power source 28, the radio-frequency
electrical current from the first radio-frequency power source 28
may flow from the central portion to the peripheral edge portion of
the wafer W instead of falling down from the central portion of the
wafer W toward the dielectric layer 21. As a result, it is
difficult to produce an electric field resulting from the
radio-frequency electrical power falling down to the dielectric
layer 21 and passing through the wafer W.
[0151] If the electric field passing through the wafer W is hardly
produced, TM mode hollow cylindrical resonance does not occur in
the central portion of the wafer W, the electron density of the
plasma increases in the central space, and the distribution of
etching speeds over the surface of the wafer W becomes non-uniform
as described above. Moreover, galvanic electric current as shown in
FIG. 2B is produced, and as a result, the gate oxide film in the
device on the wafer W is damaged and degraded due to charge-up.
[0152] Here, as is the case with the skin depth .delta..sub.w of
the electrode film 37, the skin depth .delta..sub.w of the wafer W
is expressed by the following equation (8):
.delta..sub.w=(2.rho..sub.vw/.mu..sub.w.omega.).sup.1/2=(.rho..sub.vw/(.-
mu..sub.w.pi.f)).sub.1/2 (8)
where .mu..sub.w is a magnetic permeability (H/m) of the wafer W,
.omega. is 2 .pi.f (.pi.: the ratio of the circumference of a
circle to its diameter, and f: the frequency (Hz) of
radio-frequency electrical power supplied from the first
radio-frequency power source 28), and .rho..sub.vw is a specific
resistance (.OMEGA.m) of an electrode material constituting the
wafer W.
[0153] The permeability (E.sub.w/E.sub.0w) at which the electric
field of the radio-frequency electrical power supplied from the
first radio-frequency power source 28 passes through the wafer W is
proportional to "exp(-z.sub.w/.delta..sub.w)" as expressed by the
following equation (9):
E.sub.w/E.sub.0w.varies.exp(-z.sub.w/.delta..sub.w). (9)
Where z.sub.w is the thickness (m) of the wafer W, and E.sub.0w is
the intensity of the electric field incident on the wafer W.
[0154] As is obvious from the above equation (9), it was found that
to produce an electric field passing through the wafer W, it is
only necessary to increase the skin depth .delta..sub.w of the
wafer W, and to increase the skin depth .delta..sub.w of the wafer
W, it is only necessary to increase the resistance R.sub.w of the
wafer W using an electrode material having a high specific
resistance .rho..sub.vw.
[0155] Accordingly, the inventors of the present invention prepared
a plurality of test wafers having different specific resistances
.rho..sub.vw so as to find a specific resistance .rho..sub.vw of
the wafer W that can make the distribution of etching speeds over
the surface of the wafer W uniform. Then, the inventors of the
present invention carried out the RIE on the test wafers in the
plasma processing apparatus 10, observed the distribution of
etching speeds over the surfaces of the test wafers, and graphed
the observation results in FIG. 9. The specific resistances
.rho..sub.vw of the respective test wafers used here were 1.9
.OMEGA.cm and 4.0 .OMEGA.cm.
[0156] Moreover, in the RIE, a mixed gas of N.sub.2 gas, O.sub.2
gas, and CH.sub.4 gas (flow ratio: N.sub.2 gas/O.sub.2 gas/CH.sub.4
gas=100/10/45 sccm) was introduced as a process gas into the upper
chamber 11a, the frequency of radio-frequency electrical power
supplied from the first radio-frequency power source 28 was set to
100 MHz, the value thereof was set to 2400 W, the frequency of
radio-frequency electrical power supplied from the second
radio-frequency power source 29 was set to 3.2 MHz, and the value
thereof was set to 200 W.
[0157] In the graph of FIG. 9, the abscissa indicates the distance
from the center of the test wafer, and the ordinate indicates the
etching speed (nm/min). The broken line corresponds to the case
that the specific resistances .rho..sub.vw=1.9 .OMEGA.cm, and the
solid line corresponds to the case that the specific resistances
.rho..sub.vw=4.0 .OMEGA.cm.
[0158] From the graph of FIG. 9, it was found that if the specific
resistances .rho..sub.vw is not less than 4.0 .OMEGA.cm, the
distribution of etching speeds over the surface of the wafer W can
be made substantially uniform. Moreover, because the test wafers
had a thickness of 775 .mu.m and a diameter of 300 mm, it was found
from the above results that if .delta..sub.w/z.sub.w is not less
than 13, or the surface resistivity .rho..sub.sw of the wafer W is
not less than 52.OMEGA./.quadrature., the distribution of etching
speeds over the surface of the wafer W can be made substantially
uniform.
[0159] Moreover, if the resistance R.sub.1 of a wiring film, not
shown, on the wafer W is low, radio-frequency electric current from
the second radio-frequency power source 28 may flow from the
central portion to the peripheral edge portion of the wafer W via
the wiring film instead of falling down from the central portion
down toward the dielectric layer 21. As a result, as described
above, the distribution of etching speeds over the surface of the
wafer W becomes non-uniform, and galvanic electric current as shown
in FIG. 2B is produced, and the gate oxide film in the device on
the wafer W is damaged and degraded due to charge-up.
[0160] Accordingly, to produce an electric field passing through
the wiring film, it is only necessary to increase the skin depth
.delta..sub.1 of the wiring film expressed by the following
equation (10), and to increase the skin depth .delta..sub.1 of the
wiring film, it is only necessary to increase the resistance
R.sub.1 of the wiring film using an electrode material having a
high specific resistance .rho..sub.v1:
.delta..sub.1=(2.rho..sub.v1/(.mu..sub.1.omega.)).sup.1/2=(.rho..sub.v1/-
(.mu..sub.1.pi.f)).sup.1/2 (10)
where .mu. is a magnetic permeability (H/m) of the wiring film,
.omega. is 2 .pi.f (.pi.: the ratio of the circumference of a
circle to its diameter, and f: the frequency (Hz) of
radio-frequency electrical power supplied from the first
radio-frequency power source 28), and .rho..sub.v1 is a specific
resistance (.OMEGA.m) of an electrode material of the wiring
film.
[0161] Here, because .delta..sub.w/z.sub.w of the wafer W has to be
not less than 13, and the surface resistivity .rho..sub.sw of the
wafer W has to be not less than 52.OMEGA./.quadrature. so as to
make the distribution of etching speed over the surface of the
wafer W substantially uniform as described above,
.delta..sub.1/z.sub.1 of the wiring film is also set to be not less
than 13, and the surface resistivity of the wiring film is also set
to be not less than 52.OMEGA./.quadrature.. It should be noted that
z.sub.1 is the thickness (m) of the wiring film.
[0162] FIG. 10 is an enlarged cross-sectional view schematically
showing the construction of the electrostatic chuck in FIG. 1 and
its vicinity.
[0163] Referring to FIG. 10, the electrostatic chuck 22 has a
disk-shaped base material 22a that is made of a sintered material
such as ceramics, the electrode film 37 that is formed on a surface
(upper side as viewed in the drawing) of the base material 22a, a
disk-shaped upper material 22b (insulating material) that is made
of a sintered material which is ceramics, laminated on the
electrode film 37, and attached to the electrode film 37 and the
base material 22a by pressure, and a cylindrical conductive member
45 that has one end thereof being in contact with the electrode
film 37 and has the other end thereof being exposed from a rear
surface (lower side as viewed in the drawing) of the base material
22a.
[0164] The electrostatic chuck 22 is mounted on the upper surface
of the lower electrode 20 and attached to the lower electrode 20 by
an insulating adhesive agent 46 (for example, an adhesive agent
with a filler). At this time, the other end of the conductive
member 45 is electrically connected to the high-voltage DC power
source 42 via a conducting bar 47. Thus, the high-voltage DC power
source 42 can supply high-output DC voltage to the electrode film
37.
[0165] Next, a description will be given of how the electrostatic
chuck 22 is manufactured.
[0166] First, the base material 22a is prepared/formed in advance,
and the electrode film 37 is formed on a surface of the base
material 22a by screen printing.
[0167] Then, the base material 22a and the electrode film 37 are
covered with the upper material 22b that is separately
prepared/formed, and the base material 22a, electrode film 37, and
upper material 22b are attached to one another by pressure through
hot pressing, and the electrode film 37 is hardened and stabilized
in its physicality, whereby the electrostatic chuck 22 is
obtained.
[0168] In the screen printing, Al.sub.2O.sub.3--MoC or a
carbon-containing material is used. By adjusting the contained
amount of MoC or carbon, the electrode film 37 whose specific
resistance lies inside a semiconductor region, specifically,
1.0.times.10.sup.-2 .OMEGA.cm to 1.0.times.10.sup.3 .OMEGA.cm can
be easily formed. In general, because a film with a thickness of
several .mu.m to 100 .mu.m can be suitably formed in the screen
printing, the screen printing can be used as a method of forming
the electrode film 37 whose thickness has to be set to several
.mu.m to 100 .mu.m in the case that the specific resistance is set
to 1.0.times.10.sup.-2 .OMEGA.cm to 1.0.times.10.sup.3
.OMEGA.cm.
[0169] As described above, the electrode film 37 of the present
embodiment has to have the skin depth .delta. and the thickness Z
satisfying the condition that ".delta./z.gtoreq.85", and the
surface resistivity .rho..sub.s satisfying the condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.", it is
necessary to manage the surface resistivity .rho..sub.s of the
electrode film 37. However, as described above, in the case that
the electrode film 37 is formed by the screen printing and further
hardened by the hot pressing, the electrode film 37 is covered with
the upper material 22b and then hardened to be stabilized in its
property, and it is thus impossible to measure the resistance value
of the electrode film 37 in the process of manufacturing the
electrostatic chuck 22. To cope with this, in the present
embodiment, as a method of forming the electrode film 37 in the
electrostatic chuck 22, thermal spraying, thin-film formation,
coating (except for screen printing), attachment of a conductive
film (for example, a metallic thin film), or the like is used.
[0170] In the thermal spraying, for example, the electrode film 37
having a specific resistance inside a semiconductor region,
specifically, a specific resistance of 1.0.times.10.sup.-2
.OMEGA.cm to 1.0.times.10.sup.3 .OMEGA.cm can be easily formed by
using Al.sub.2O.sub.3--Cr.sub.2O.sub.3 or silicon as a thermal
spraying material. In general, because a film having a thickness of
several .mu.m to 100 .mu.m can be suitably formed in the thermal
spraying, the thermal spraying is preferable as the method of
forming the electrode film 37. Also, in the coating, a
thermosetting coating, for example, a carbon-containing material is
used, and the electrode film 37 is formed by heating and hardening
the coated coating.
[0171] Examples of the thin-film formation include PVD in which a
thin film of copper, aluminum, or gold is formed, CVD or liquid
deposition in which a thin film of tungsten or titanium is formed,
plating method (electroless nickel plating) or a sol-gel method. By
using these kinds of thin-film formation, the electrode film 37
having a specific resistance inside a low resistance region,
specifically, a specific resistance of 1.0.times.10.sup.-6
.OMEGA.cm to 0.1 .OMEGA.cm and having a thickness of 10 .mu.m or
less can be easily formed.
[0172] By using the thermal-spraying, coating, and thin-film
formation described above, the electrode film 37 can be hardened
and stabilized in physical properties before the electrode film 37
is covered with the upper material 22b, that is, in a state of
being exposed.
[0173] In the method of manufacturing the electrostatic chuck 22
according to the present embodiment, at the time point when the
electrode film 37 is hardened, the surface resistivity .rho..sub.s,
thickness z, and so on of the electrode film 37 are measured, it is
determined whether or not the skin depth .delta. and the thickness
z of the electrode film 37 satisfy the condition that
".delta./z.gtoreq.85" and the surface resistivity .rho..sub.s
satisfies the condition that
".rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA./.quadrature.", or
whether or not the surface resistivity .rho..sub.s of the electrode
film 37 satisfies the condition that "115
.OMEGA./.quadrature..ltoreq..rho..sub.s.ltoreq.2.67.times.10.sup.5.OMEGA.-
/.quadrature.." If the electrode film 37 does not satisfy these
conditions, the base material 22a and the electrode film 37 are
discarded. After that, the base material 22a and the electrode film
37 are covered with the upper material 22b, and the base material
22a, electrode film 37, and upper material 22a are attached to one
another by pressure, whereby the electrostatic chuck 22 is
obtained.
[0174] According to the method of manufacturing the electrostatic
chuck 22 described above, because the electrode film 37 is formed
on the surface of the base material 22a prepared/formed in advance,
and then covered with the upper material 22b, the electrode film 37
exposes itself once without exception before being covered with the
upper material 22b in the process of manufacturing the
electrostatic chuck 22. This makes it possible to measure the
surface resistivity .rho..sub.s and so on of the electrode film 37
in the process of manufacturing the electrostatic chuck 22 and thus
makes it possible to manage the surface resistivity .rho..sub.s and
so on of the included electrode film 37.
[0175] Although in the electrostatic chuck 22 described above, the
upper material 22b is attached to the electrode film 37 and the
base material 22a by pressure, the upper material 22b may be
attached to the base material 22a and the electrode film 37 by an
insulating adhesive agent, not shown. The insulating adhesive agent
can reliably insulate high-power DC voltage applied to the
electrode film 37, and reliably attach the upper material 22b to
the base material 22a.
[0176] Although in the electrostatic chuck 22 described above, the
electrode film 37 is formed on the surface of the upper material
22b, a dielectric layer 48 that is constructed such as to cover the
whole upper surface of the lower electrode 20 may be buried in the
lower electrode 20, the electrode film 37 may be directly formed on
an upper surface of the dielectric layer 48, and then the upper
material 22b may be attached to the electrode film 37 and the
dielectric layer 48 by pressure. This can reduce the number of
component parts of the mounting stage 12. The dielectric layer 48
is formed by sintering or thermal spraying of ceramics, or a
combination of both.
[0177] Moreover, the electrode film 37 may be formed on a rear
surface (lower side as viewed in the drawing) of the upper material
22b (base material) by the thermal spraying or thin-film formation
described above, and the upper material 22b may be attached to the
dielectric layer 48 by an insulating adhesive agent 46 (FIG. 11A).
At this time, a layer comprised of an insulating adhesive agent is
not superposed between a surface (an upper side as viewed in the
drawing) that acts as an upper surface of the electrostatic chuck
22 and directly contacts the wafer W and the electrode film 37, the
electrostatic attracting force with which the electrostatic chuck
22 electrostatically attracts a wafer W becomes more stable. It
should be noted that in the case that the electrode film 37 is
formed on the rear surface of the upper material 22b, it is
preferred that the surface of the electrode film 37 is coated with
an insulating coating film. This can improve the insulation
performance of the electrostatic chuck 22. The insulating coating
film corresponds to the base material 22a appearing in FIG. 10 and
is formed by the thermal spraying, the thin-film formation, or the
like.
[0178] In the electrostatic chuck 22 described above, because the
upper material 22b is a sintered material, the wafer W that is
electrostatically attracted by the electrostatic chuck 22 contacts
the sintered material. Because the sintered material is unlikely to
fracture, a surface layer of the upper material 22b does not
fracture even if the upper material 22b contacts the wafer W. Thus,
particles resulting from the fracture of the surface layer of the
upper material 22b can be prevented from being produced. Moreover,
in the case that the electrode film 37 is formed on the rear
surface of the upper material 22b comprised of the sintered
material by the thermal spraying, it is preferred that an
underlayer with high wettability is formed in advance on the rear
surface of the upper material 22b (the surface facing the base
material) so as to increase the degree of bonding between the
sintered material and the electrode film 37 formed by the thermal
spraying. This can further increase bonding force with which the
upper material 22b and the electrode film 37 formed by the thermal
spraying are bonded together.
[0179] Although in the electrostatic chuck 22 described above, the
sintered material is used as the upper material 22b, the upper
material 22b may be formed by thermal spraying of an insulating
material or attachment of an insulating film. This can reliably
form an insulating layer on the electrode Film 37.
[0180] In the case that the upper material 22b is formed on the
electrode film 37 by thermal spraying of insulating ceramics such
as Al.sub.2O.sub.3, it is preferred that the electrode film 37 is
also formed on the surface of the base material 22a by thermal
spraying. This makes it possible to form almost all of the
electrostatic chuck 22 by thermal spraying, and thus manufacture
the electrostatic chuck 22 at low cost.
[0181] In the case that the upper material 22b is formed by
attachment of an insulating film, an electrostatic chuck 49 may be
constructed by attaching a conductive tape 50 of which a metallic
thin film is evaporated on the base material 22a prepared/formed in
advance, and attaching an insulating film, for example, a polyimide
tape 51 on the conductive tape 50 (FIG. 11B). In this case, it is
preferred that the metallic thin film evaporated on the tape 50 is
made of, for example, copper or aluminum.
[0182] Moreover, although in the electrostatic chuck 22 described
above, the electrode film 37 and the base material 22a are
configured as separate bodies, a base material 52 may be made of a
sintered material comprised of a tight layer 52a and a loose layer
52b formed on the tight layer 52a, and a conductive material may be
impregnated in the loose layer 52b to configure an electrode layer
53 and the base material 52 as an integral unit (see FIGS. 12A and
12B). In this case, it is preferred that after the electrode layer
53 is formed, the base material 52 and the electrode layer 53 are
covered with the upper material 22b separately prepared/formed, and
the base material 52, electrode layer 53, and upper material 22b
are attached to one another by pressure. This causes the electrode
layer 53 to expose itself once without exception before being
covered with the upper material 22b in the process of manufacturing
the electrostatic chuck. As a result, in the process of
manufacturing the electrostatic chuck, the surface resistivity
.rho..sub.s and so on of the electrode layer 53 can be measured,
and hence the surface resistivity .rho..sub.s of the included
electrode layer 53 can be managed. Moreover, because the base
material 52 has the loose layer 52b, the conductive material can be
reliably impregnated in the base material 52.
[0183] Further, conductive linear members may be combined together
in a mesh-like fashion to construct an electrode film 54 (FIG. 13).
In the electrode film 54, the surface resistivity .rho..sub.s per
unit area can be easily adjusted by adjusting the size of
meshes.
[0184] It should be noted that in the case that the electrode film
37 is formed by screen printing and then hardened by the hot
pressing, the electrode film 37 never exposes itself in the
hardened state in the process of manufacturing the electrostatic
chuck 22, and hence the resistance value of the electrode film 37
cannot be measured in the process of manufacturing the
electrostatic chuck 22. In this case, it is preferred that the
electrostatic chuck 22 is provided with at least two conductive
members 45, and in particular, it is preferred that one of the
conductive members 45 is disposed in the central portion of the
electrostatic chuck 22. Specifically, one conductive member 45 is
disposed in the central portion of the electrostatic chuck 22, and
the other plurality of conductive members 45 are disposed at
regular intervals on the same circumference in a peripheral edge
portion of the electrostatic chuck 22 (FIGS. 14A and 14B). In this
case, by bringing two terminals of a tester into contact with the
respective two conductive members 45, the surface resistivity
.rho..sub.s of the electrode film 37 can be measured and managed
with ease after the electrostatic chuck 22 is manufactured. In
particular, if one of the two terminals of the tester is brought
into contact with the conductive members 45 disposed in the central
portion of the electrostatic chuck 22, the surface resistivity
.rho..sub.s of the electrode film 37 can be managed by measuring
the resistance from the central portion to the peripheral edge
portion of the electrode film 37.
[0185] Although in the above described embodiment, the substrates
subjected to the RIE or the ashing are semiconductor wafers W, but
the substrates subjected to the RIE or the ashing are not limited
to being semiconductor wafers W, and rather may instead be any of
various glass substrates used in LCDs (Liquid Crystal Displays),
FPDs (Flat Panel Displays), or the like.
* * * * *