U.S. patent application number 15/586577 was filed with the patent office on 2017-08-17 for manufacturing method for component in plasma processing apparatus.
The applicant listed for this patent is Tocalo Co., Ltd., Tokyo Electron Limited. Invention is credited to Shikou Abukawa, Yoshinori Kanazawa, Koji Mitsuhashi, Masaya Nagai, Nobuyuki Nagayama, Tetsuya Niya.
Application Number | 20170233860 15/586577 |
Document ID | / |
Family ID | 55454188 |
Filed Date | 2017-08-17 |
United States Patent
Application |
20170233860 |
Kind Code |
A1 |
Nagayama; Nobuyuki ; et
al. |
August 17, 2017 |
MANUFACTURING METHOD FOR COMPONENT IN PLASMA PROCESSING
APPARATUS
Abstract
A manufacturing method for a component in a plasma processing
apparatus is provided. The method includes: performing a surface
conditioning on a surface of an underlying layer on which a film is
to be formed by thermal spraying, the surface of the underlying
layer includes a surface of a base or a surface of a layer formed
on the surface of the base; and forming the film on the surface of
the underlying layer by thermally spraying yttrium fluoride. A high
velocity oxygen fuel spraying method or an atmospheric plasma
spraying method is used in the forming of the film.
Inventors: |
Nagayama; Nobuyuki;
(Kurokawa-gun, JP) ; Mitsuhashi; Koji;
(Kurokawa-gun, JP) ; Abukawa; Shikou; (Akashi,
JP) ; Nagai; Masaya; (Funabashi, JP) ;
Kanazawa; Yoshinori; (Funabashi, JP) ; Niya;
Tetsuya; (Funabashi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tokyo Electron Limited
Tocalo Co., Ltd. |
Tokyo
Kobe-shi |
|
JP
JP |
|
|
Family ID: |
55454188 |
Appl. No.: |
15/586577 |
Filed: |
May 4, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14854411 |
Sep 15, 2015 |
|
|
|
15586577 |
|
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Current U.S.
Class: |
427/453 |
Current CPC
Class: |
C23C 4/02 20130101; C23C
28/042 20130101; C23C 4/131 20160101; C23C 4/01 20160101; C23C 4/11
20160101; C23C 4/134 20160101; C23C 4/06 20130101 |
International
Class: |
C23C 4/134 20060101
C23C004/134; C23C 4/11 20060101 C23C004/11; C23C 4/06 20060101
C23C004/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2014 |
JP |
2014-188695 |
Jun 29, 2015 |
JP |
2015-129940 |
Claims
1. A manufacturing method for a component in a plasma processing
apparatus, the manufacturing method comprising: performing a
surface conditioning on a surface of an underlying layer on which a
film is to be formed by thermal spraying, the surface of the
underlying layer includes a surface of a base or a surface of a
layer formed on the surface of the base; and forming the film on
the surface of the underlying layer by thermally spraying yttrium
fluoride, wherein, a high velocity oxygen fuel spraying method or
an atmospheric plasma spraying method is used in the forming of the
film, and in the forming of the film, a slurry containing yttrium
fluoride particles having an average diameter ranging from 1 .mu.m
to 8 .mu.m is supplied, from a nozzle of a spraying gun configured
to jet a flame in the high velocity oxygen fuel spraying method or
from a nozzle of a spraying gun configured to discharge a plasma
jet in the atmospheric plasma spraying method, to a position
distanced apart from the nozzle of the spraying gun toward a
downstream side in a direction of a central axis line of the nozzle
of the spraying gun or to a position corresponding to a tip end of
the nozzle of the spraying gun.
2. The manufacturing method of claim 1, wherein the high velocity
oxygen fuel spraying method is used in the forming of the film, and
the position to which the slurry is supplied is in the range from 0
mm to 100 mm from the tip end of the nozzle in the direction of the
central axis line.
3. The manufacturing method of claim 1, wherein the atmospheric
plasma spraying method is used in the forming of the film, and the
position to which the slurry is supplied is in the range from 0 mm
to 30 mm from the tip end of the nozzle in the direction of the
central axis line.
4. The manufacturing method of claim 1, wherein an angle between a
central axis line of a slurry supplying nozzle configured to supply
the slurry and the central axis line of the nozzle of the spraying
gun ranges from 45 degrees to 135 degrees at a side of the tip end
of the nozzle of the spraying gun.
5. The manufacturing method of claim 1, wherein a temperature of
the base is set to be in a range from 100.degree. C. to 300.degree.
C. in the forming of the film.
6. The manufacturing method of claims 1, further comprising:
forming a first intermediate layer made of yttrium oxide between
the base and the film.
7. The manufacturing method of claim 6, further comprising: forming
a mask on a region including an edge of the first intermediate
layer, wherein the forming of the film is performed while the mask
is formed on the region including the edge of the first
intermediate layer in the forming of the mask.
8. The manufacturing method of claim 6, further comprising: forming
a second intermediate layer between the first intermediate layer
and the film.
9. The manufacturing method of claim 8, wherein the second
intermediate layer has a linear expansion coefficient that falls
between a linear expansion coefficient of the first intermediate
layer and a linear expansion coefficient of the film.
10. The manufacturing method of claim 9, wherein the second
intermediate layer is made of a thermally sprayed film of
yttria-stabilized zirconia (YSZ), or a thermally sprayed film of
forsterite.
11. The manufacturing method of claim 8, wherein the second
intermediate layer is made of a thermally sprayed film of alumina
or a thermally sprayed film of gray alumina.
12. The manufacturing method of claim 6, further comprising:
forming another intermediate layer between the base and the first
intermediate layer.
13. The manufacturing method of claim 12, wherein the another
intermediate layer is made of a thermally sprayed film of alumina
or a thermally sprayed film of gray alumina.
14. The manufacturing method of claim 1, further comprising:
forming an alumite film on the surface of the base.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a divisional application of U.S. patent application
Ser. No. 14/854,411, filed on Sep. 15, 2015 which claims the
benefit of Japanese Patent Application Nos. 2014-188695 and
2015-129940 filed on Sep. 17, 2014 and Jun. 29, 2015, respectively,
the entire disclosures of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The embodiments described herein pertain generally to a
manufacturing method for a component in a plasma processing
apparatus.
BACKGROUND
[0003] In the manufacture of an electronic device such as a
semiconductor device, plasma etching is performed on a processing
target object. The degree of accuracy required for the plasma
etching is getting higher year by year as the electronic device is
getting more miniaturized. To achieve the high accuracy of the
plasma etching, particle generation needs to be suppressed.
[0004] A processing vessel of a plasma processing apparatus used
for this plasma etching is made of a metal such as aluminum. An
inner wall surface of the processing vessel is exposed to plasma.
Thus, in a plasma processing apparatus, a plasma-resistant film is
formed on an inner wall of the processing vessel. Generally, such a
film is made of yttrium oxide (yttria).
[0005] If this yttrium oxide film is exposed to plasma of a
fluorocarbon-based gas, it reacts with active species such as
fluorine in the plasma. As a result, the yttrium oxide film is
consumed. To solve this problem, it is recently attempted to form
the film on the inner wall of the processing vessel with yttrium
fluoride. This yttrium fluoride film is formed by thermal spraying,
as described in Patent Document 1.
[0006] Patent Document 1: Japanese Patent Laid-open Publication No.
2013-140950
[0007] As higher level of accuracy is required for the plasma
etching, it is required to suppress even the particles having small
sizes which have been never regarded as problems conventionally.
For this purpose, particle generation from the thermally sprayed
yttrium fluoride film needs to be further suppressed.
SUMMARY
[0008] In one exemplary embodiment, there is provided a component
exposed to plasma in a plasma processing apparatus. The component
includes a base and a film. The base, for example, is made of
aluminum or an aluminum alloy, and an alumite film may be formed on
a surface of the base. The film is formed by thermally spraying
yttrium fluoride onto the surface of the base or on a surface of an
underlying layer including a layer provided on the base. In the
component, a porosity of the film is 4% or less, and an arithmetic
mean roughness (Ra) of the surface of the film is 4.5 .mu.m or
less. The arithmetic mean roughness (Ra) is defined by JIS
B0601-1994.
[0009] In the component, the film covering the base is a thermally
sprayed film of yttrium fluoride. This film has a low porosity and
is a dense film having a small specific surface area. Accordingly,
a little change in the surface thereof occurs even when it is
exposed to the plasma, and, thus, a variation in process
performance can be reduced. Therefore, according to this
manufacturing method PM, it is possible to form a film capable of
suppressing the particle generation.
[0010] The component may further include a first intermediate layer
which is made of an yttrium oxide film formed by an atmospheric
plasma spraying method, and is provided between the base and the
film. The component in the plasma processing apparatus may be
required to have a high breakdown voltage. However, the thermally
sprayed film of yttrium fluoride has a relatively low breakdown
voltage. In accordance with the exemplary embodiment, since the
first intermediate layer formed by a thermally sprayed film of
yttrium oxide is provided as an underlying layer of the film, the
multilayered film including the film and the first intermediate
layer and having a high breakdown voltage is provided on the
base.
[0011] The film may not be formed on a region including an edge of
the first intermediate layer, but may be formed on the first
intermediate layer at an inner side than the region. An adhesive
strength of the yttrium fluoride film to the base is relatively
low. In accordance with the exemplary embodiment, since the film is
not contact with the base at the edge region, peeling of the film
can be suppressed.
[0012] The component may include a second intermediate layer
provided between the first intermediate layer and the film. The
second intermediate layer may have a linear expansion coefficient
that falls between the linear expansion coefficient of the first
intermediate layer and the linear expansion coefficient of the
film. In accordance with the exemplary embodiment, the peeling of
the film that might be caused by a difference in the linear
expansion coefficients between the film and the first intermediate
layer can be suppressed. By way of example, the second intermediate
layer may be formed of a thermally sprayed film of forsterite or a
thermally sprayed film of yttria-stabilized zirconia (YSZ) formed
by the atmospheric plasma spraying method. Further, the second
intermediate layer may be made of a thermally sprayed film of gray
alumina or a thermally sprayed film of alumina formed by the
atmospheric plasma spraying method. The multilayered film including
the film, the first intermediate layer and the second intermediate
layer and having a high breakdown voltage is provided on the
base.
[0013] The component may include another intermediate layer
provided between the base and the first intermediate layer. By way
of example, the another intermediate layer can be formed of a
thermally sprayed film of gray alumina or a thermally sprayed film
of alumina formed by the atmospheric plasma spraying method. In
accordance with the exemplary embodiment, the multilayered film
including the film, the first intermediate layer and the another
intermediate layer and having a high breakdown voltage is provided
on the base.
[0014] In another exemplary embodiment, there is provided a
manufacturing method for the above-described component in the
plasma processing apparatus. The manufacturing method includes
performing a surface conditioning on a surface of an underlying
layer on which a film is to be formed by thermal spraying, and the
surface of the underlying layer includes a surface of a base or a
surface of a layer formed on the surface of the base; and forming
the film on the surface of the underlying layer by thermally
spraying yttrium fluoride. A high velocity oxygen fuel spraying
method or an atmospheric plasma spraying method is used in the
forming of the film. In the forming of the film, a slurry
containing yttrium fluoride particles having an average diameter
ranging from 1 .mu.m to 8 .mu.m is supplied, from a nozzle of a
spraying gun configured to jet a flame in the high velocity oxygen
fuel spraying method or from a nozzle of a spraying gun configured
to discharge a plasma jet in the atmospheric plasma spraying
method, to a position distanced apart from the nozzle of the
spraying gun toward a downstream side in a direction of a central
axis line of the nozzle of the spraying gun or to a position
corresponding to a tip end of the nozzle of the spraying gun.
[0015] In this manufacturing method, since the film is formed on
the surface of the underlying layer on which a surface conditioning
is performed, the film has a low surface roughness. Since this film
has a small specific surface area, a little change in the surface
thereof occurs even when it is exposed to the plasma, and, thus, a
variation in process performance can be reduced. Therefore,
according to this manufacturing method PM, it is possible to form a
film capable of suppressing the particle generation. Further, since
the average diameter of the particles contained in the slurry is in
the range from 1 .mu.m to 8 .mu.m, aggregation between the
particles is suppressed, so that the uniform film can be formed.
Moreover, since the average diameter of the particles contained in
the slurry is in the range from 1 .mu.m to 8 .mu.m, the film having
a high adhesivity between the particles can be formed. In addition,
since the slurry is supplied to the aforementioned position,
adhesion of the sprayed material to an inner wall of a nozzle of
the spraying gun can be suppressed. As a result, spitting can be
suppressed. Thus, according to this manufacturing method, it is
possible to form a film having a low porosity and a small specific
surface area, that is, a highly dense film. Since the formed film
is highly dense, it has a high cross sectional hardness. Therefore,
according to the present manufacturing method, it is possible to
form a film capable of suppressing particle generation.
[0016] The high velocity oxygen fuel spraying method may be used in
the forming of the film, and the position to which the slurry is
supplied may be in the range from 0 mm to 100 mm from the tip end
of the nozzle in the direction of the central axis line.
[0017] The atmospheric plasma spraying method may be used in the
forming of the film, and the position to which the slurry is
supplied may be in the range from 0 mm to 30 mm from the tip end of
the nozzle in the direction of the central axis line.
[0018] An angle between a central axis line of a slurry supplying
nozzle configured to supply the slurry and the central axis line of
the nozzle of the spraying gun may range from 45 degrees to 135
degrees at a side of the tip end of the nozzle of the spraying
gun.
[0019] A temperature of the base may be set to be in a range from
100.degree. C. to 300.degree. C. in the forming of the film. The
yttrium fluoride has a high thermal expansion coefficient. Thus, if
the sprayed yttrium fluoride particles adhere to the surface of an
underlying layer, those thermally sprayed particles may be rapidly
cooled to be aggregated. As a result, the crack can occur in the
film being formed. In accordance with the exemplary embodiment,
since the temperature of the base is set to be in the range from
100.degree. C. to 300.degree. C., the crack in the film can be
suppressed.
[0020] The manufacturing method may further include forming a first
intermediate layer made of yttrium oxide between the base and the
film. The first intermediate layer may be formed by the thermally
spraying.
[0021] The manufacturing method may further include forming a mask
on a region including an edge of the first intermediate layer.
Here, the forming of the film is performed while the mask is formed
on the region including the edge of the first intermediate layer in
the forming of the mask. In accordance with the exemplary
embodiment, it is possible to form the film only on the region of
the first intermediate layer at the inner side than the edge of the
first intermediate layer.
[0022] The manufacturing method may further include forming a
second intermediate layer between the first intermediate layer and
the film. The second intermediate layer may have a linear expansion
coefficient that falls between a linear expansion coefficient of
the first intermediate layer and a linear expansion coefficient of
the film. By way of example, the second intermediate layer may be
made of a thermally sprayed film of yttria-stabilized zirconia
(YSZ), or a thermally sprayed film of forsterite. Alternatively,
the second intermediate layer may be made of a thermally sprayed
film of alumina or a thermally sprayed film of gray alumina. The
second intermediate layer made of any of these materials can be
formed by the thermally spraying.
[0023] The manufacturing method may further include forming another
intermediate layer between the base and the first intermediate
layer. Here, the another intermediate layer may be made of a
thermally sprayed film of alumina or a thermally sprayed film of
gray alumina. The another intermediate layer made of any of these
materials can be formed by the thermally spraying.
[0024] The manufacturing method may further include forming an
alumite film on the surface of the base.
[0025] According to the exemplary embodiments, it is possible to
suppress generation of particles from the yttrium fluoride
film.
[0026] The foregoing summary is illustrative only and is not
intended to be in any way limiting. In addition to the illustrative
aspects, embodiments, and features described above, further
aspects, embodiments, and features will become apparent by
reference to the drawings and the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In the detailed description that follows, embodiments are
described as illustrations only since various changes and
modifications will become apparent to those skilled in the art from
the following detailed description. The use of the same reference
numbers in different figures indicates similar or identical
items.
[0028] FIG. 1 is a diagram illustrating an example of a plasma
processing apparatus;
[0029] FIG. 2 is an enlarged cross sectional view illustrating a
part of a component for a plasma processing apparatus according to
an exemplary embodiment;
[0030] FIG. 3 is an enlarged cross sectional view illustrating a
part of a component for the plasma processing apparatus according
to another exemplary embodiment;
[0031] FIG. 4A and FIG. 4B are enlarged cross sectional views
illustrating a part of a component for the plasma processing
apparatus according to still another exemplary embodiment;
[0032] FIG. 5 is a flowchart for describing a manufacturing method
according to the exemplary embodiment;
[0033] FIG. 6A and FIG. 6B are diagrams illustrating a product
produced in individual processes of the manufacturing method
depicted in FIG. 5;
[0034] FIG. 7A to FIG. 7D are diagrams illustrating the product
produced in individual processes of the manufacturing method
depicted in FIG. 5;
[0035] FIG. 8 is a diagram for describing a high-velocity oxygen
fuel spraying method according to the exemplary embodiment;
[0036] FIG. 9 is a diagram for describing an atmospheric plasma
spraying method according to the exemplary embodiment;
[0037] FIG. 10 is a graph showing a breakdown voltage of a
film;
[0038] FIG. 11 is a graph showing a breakdown voltage of a
multilayered film; and
[0039] FIG. 12 is a graph showing a relationship between a
processing time of a plasma process and the number of
particles.
DETAILED DESCRIPTION
[0040] In the following detailed description, reference is made to
the accompanying drawings, which form a part of the description. In
the drawings, similar symbols typically identify similar
components, unless context dictates otherwise. Furthermore, unless
otherwise noted, the description of each successive drawing may
reference features from one or more of the previous drawings to
provide clearer context and a more substantive explanation of the
current exemplary embodiment. Still, the exemplary embodiments
described in the detailed description, drawings, and claims are not
meant to be limiting. Other embodiments may be utilized, and other
changes may be made, without departing from the spirit or scope of
the subject matter presented herein. It will be readily understood
that the aspects of the present disclosure, as generally described
herein and illustrated in the drawings, may be arranged,
substituted, combined, separated, and designed in a wide variety of
different configurations, all of which are explicitly contemplated
herein.
[0041] First, an example plasma processing apparatus in which a
component coated with a plasma-resistant film according to various
exemplary embodiments will be explained. FIG. 1 illustrates an
example of a plasma processing apparatus. The plasma processing
apparatus 10 shown in FIG. 1 is configured as a capacitively
coupled plasma etching apparatus, and includes a processing vessel
12. The processing vessel 12 has a substantially cylindrical shape.
The processing vessel 12 is made of, but not limited to, aluminum,
and an inner wall surface thereof is anodically oxidized. This
processing vessel 12 is frame grounded.
[0042] A substantially cylindrical supporting member 14 is provided
on a bottom portion of the processing vessel 12. The supporting
member 14 is made of, by way of non-limiting example, an insulating
material. Within the processing vessel 12, the supporting member 14
is vertically extended from the bottom portion of the processing
vessel 12. Furthermore, a mounting table PD is provided within the
processing vessel 12. The mounting table PD is supported by the
supporting member 14.
[0043] The mounting table PD is configured to hold a wafer W on a
top surface thereof. The mounting table PD has a lower electrode LE
and an electrostatic chuck ESC. The lower electrode LE is provided
with a first plate 18a and a second plate 18b. The first plate 18a
and the second plate 18b are made of a metal such as, but not
limited to, aluminum, and each thereof has a substantially disk
shape. The second plate 18b is provided on the first plate 18a and
electrically connected with the first plate 18a.
[0044] The electrostatic chuck ESC is provided on the second plate
18b. The electrostatic chuck ESC includes a pair of insulating
films or insulating sheets; and an electrode embedded therebetween.
The electrode of the electrostatic chuck ESC is made of a
conductive film and is electrically connected to a DC power supply
22 via a switch 23. The electrostatic chuck ESC is configured to
attract the wafer W by an electrostatic force such as a Coulomb
force generated by a DC voltage applied from the DC power supply
22. Accordingly, the electrostatic chuck ESC is capable of holding
the wafer W thereon.
[0045] A focus ring FR is provided on a peripheral portion of the
second plate 18b to surround an edge of the wafer W and the
electrostatic chuck ESC. The focus ring FR is provided to improve
etching uniformity. The focus ring FR is made of a material which
is appropriately selected depending on a material of an etching
target film. For example, the focus ring FR may be made of
quartz.
[0046] A coolant path 24 is provided within the second plate 18b.
The coolant path 24 constitutes a temperature controller. A coolant
is supplied into the coolant path 24 from a chiller unit provided
outside of the processing vessel 12 via a pipeline 26a. The coolant
supplied into the coolant path 24 is then returned back into the
chiller unit via a pipeline 26b. In this way, the coolant is
supplied into and circulated through the coolant path 24. A
temperature of the wafer W held by the electrostatic chuck ESC is
controlled by adjusting a temperature of the coolant.
[0047] Furthermore, the plasma processing apparatus 10 is provided
with a gas supply line 28. The gas supply line 28 supplies a heat
transfer gas, for example, a He gas, from a heat transfer gas
supply device into a gap between a top surface of the electrostatic
chuck ESC and a rear surface of the wafer W.
[0048] The plasma processing apparatus 10 is also equipped with a
heater HT as a heating device. The heater HT is embedded within,
for example, the second plate 18b, and is connected to a heater
power supply HP. As a power is supplied to the heater HT from the
heater power supply HP, the temperature of the mounting table PD is
adjusted, and, thus, the temperature of the wafer W placed on the
mounting table PD can be adjusted. Alternatively, the heater HT may
be embedded within the electrostatic chuck ESC.
[0049] Further, the plasma processing apparatus 10 includes an
upper electrode 30. The upper electrode 30 is provided above the
mounting table PD, facing the mounting table PD. The lower
electrode LE and the upper electrode 30 are arranged to be
substantially parallel to each other. Formed between the upper
electrode 30 and the lower electrode LE is a processing space S in
which a plasma process is performed on the wafer W.
[0050] The upper electrode 30 is supported on an upper portion of
the processing vessel 12 via an insulating shield member 32. In the
exemplary embodiment, the upper electrode 30 may be configured to
have a variable distance in a vertical direction from a top surface
of the mounting table PD, i.e., a wafer mounting surface. The upper
electrode 30 may include an electrode plate 34 and an electrode
supporting body 36. The electrode plate 34 faces the processing
space S and is provided with a multiple number of gas discharge
holes 34a. The electrode plate 34 is an example of a component
having plasma resistance.
[0051] The electrode supporting body 36 is configured to support
the electrode plate 34 in a detachable manner, and is made of a
conductive material such as, but not limited to, aluminum. The
electrode supporting body 36 may have a water cooling structure. A
gas diffusion space 36a is formed within the electrode supporting
body 36. A multiple number of gas through holes 36b is extended
downwards from the gas diffusion space 36a, and these gas through
holes 36b respectively communicate with the gas discharge holes
34a. Further, the electrode supporting body 36 is also provided
with a gas inlet opening 36c through which a processing gas is
introduced into the gas diffusion space 36a, and this gas inlet
opening 36c is connected to a gas supply line 38.
[0052] The gas supply line 38 is connected to a gas source group 40
via a valve group 42 and a flow rate controller group 44. The gas
source group 40 includes a plurality of gas sources that supply
different kinds of gases individually. The valve group 42 includes
a multiplicity of valves, and the flow rate controller group 44
includes multiple flow rate controllers such as a mass flow
controller. Each of the gas sources belonging to the gas source
group 40 is connected to the gas supply line 38 via each
corresponding valve belonging to the valve group 42 and each
corresponding flow rate controller belonging to the flow rate
controller group 44.
[0053] Furthermore, in the plasma processing apparatus 10, a
deposition shield 46 is detachably provided along an inner wall of
the processing vessel 12. The deposition shield 46 is also provided
on an outer side surface of the supporting member 14. The
deposition shield 46 is configured to suppress an etching byproduct
(deposit) from adhering to the processing vessel 12, and is an
example of components having plasma resistance.
[0054] A gas exhaust plate 48 is provided at a bottom portion of
the processing vessel 12 and provided between the supporting member
14 and the inner wall of the processing vessel 12. The gas exhaust
plate 48 may be made of, by way of example, but not limitation, an
aluminum member coated with ceramic such as Y.sub.2O.sub.3. The
processing vessel 12 is also provided with a gas exhaust opening
12e under the gas exhaust plate 48, and the gas exhaust opening 12e
is connected with a gas exhaust device 50 via a gas exhaust line
52. The gas exhaust device 50 includes a vacuum pump such as a
turbo molecular pump and is capable of depressurizing the inside of
the processing vessel 12 to a desired vacuum level. Further, a
carry-in/out opening 12g for the wafer W is formed through a
sidewall of the processing vessel 12, and this carry-in/out opening
12g is opened or closed by a gate valve 54.
[0055] The plasma processing apparatus 10 further includes a first
high frequency power supply 62 and a second high frequency power
supply 64. The first high frequency power supply 62 is configured
to generate a first high frequency power for plasma generation.
That is, the first high frequency power supply 62 generates a high
frequency power having a frequency in a range from 27 MHz to 100
MHz, e.g., 40 MHz. The first high frequency power supply 62 is
connected to the lower electrode LE via a matching device 66. The
matching device 66 is a circuit for matching an output impedance of
the first high frequency power supply 62 and an input impedance on
a load side (lower electrode LE). Furthermore, the first high
frequency power supply 62 may be connected to the upper electrode
30 via the matching device 66.
[0056] The second high frequency power supply 64 is configured to
generate a second high frequency power for ion attraction into the
wafer W, i.e., a high frequency bias power having a frequency in a
range from 400 kHz to 13.56 MHz, e.g., 3.2 MHz. The second high
frequency power supply 64 is connected to the lower electrode LE
via a matching device 68. The matching device 68 is a circuit for
matching an output impedance of the second high frequency power
supply 64 and the input impedance on the load side (lower electrode
LE).
[0057] In the plasma processing apparatus 10 having the
above-described configuration, a gas source selected from the
plurality of gas sources belonging to the gas source group 40
supplies a gas into the processing vessel 12. Further, an internal
space of the processing vessel 12 is depressurized to a preset
pressure by the gas exhaust device 50, and plasma is generated
within the processing vessel 12 by a high frequency electric field
caused by applying the high frequency power from the first high
frequency power supply 62. Here, the inner wall surfaces of the
processing vessel 12, which form and confine the internal space
thereof, are exposed to the generated plasma. For this reason, the
deposition shield 46 and the electrode plate 34 are coated with a
film having plasma resistance.
[0058] Below, various embodiments regarding a component having
plasma resistance will be explained. FIG. 2 is an enlarged cross
sectional view illustrating a part of a component for the plasma
processing apparatus according to the exemplary embodiment. A
component 100 shown in FIG. 2 can be used as, for example, the
aforementioned deposition shield 46.
[0059] The component 100 has a base 102 and a film 104. The base
102 may be made of aluminum or an aluminum alloy. By way of
example, the base 102 is a plate-shaped body made of A5052.
Alternatively, the base 102 may be made of
alumina(Al.sub.2O.sub.3), silicon carbide, silicon oxide, silicon,
stainless steel, carbon or a combination thereof (for example,
Si--SiC or alumina-silicon carbide).
[0060] In the exemplary embodiment, the base 102 may have an
alumite film 106 formed on a main surface thereof. The alumite film
106 is formed by anodically oxidizing the base 102. In this
exemplary embodiment, the alumite film 106 is formed only at a
surface of a partial region of the base 102 including an edge
thereof.
[0061] Further, in the exemplary embodiment, the main surface of
the base 102 has a surface roughness equal to or smaller than a
preset value. As will be described later, a film formed on the main
surface of the base 102 has a surface roughness (arithmetic mean
roughness: Ra) of 4.5 .mu.m. Since the surface roughness of the
film may reflect the surface roughness of the base 102, the surface
roughness of the base 102 can be adjusted to a preset value or
less. For example, the arithmetic mean roughness of the base 102
can be adjusted to 4.5 .mu.m or less. Further, the arithmetic mean
roughness (Ra) is defined by JIS B0601-1994.
[0062] The film 104 is formed on the base 102. The film 104 is made
of yttrium fluoride and is formed by thermal spraying. The film 104
has a porosity ranging from 0.01% to 4%. In the film 104 having
this porosity, a strong binding force between particles is
obtained, so that particle generation from the film 104 can be
suppressed. The porosity is defined as a value measured by a
porosity measurement method to be described below.
[0063] [Porosity Measurement Method]
[0064] In this porosity measurement method, a field emission
scanning electron microscope SU8200 produced by Hitachi
High-Technology is used. As measurement conditions, an acceleration
voltage of 1 kV, an emission current of 20 .mu.A, and a work
distance of 8 mm are set. A porosity is measured in the following
sequence of (1) to (5). [0065] (1) An initial sample having a film
is cut. [0066] (2) A cut surface is smoothed and cleaned by ion
milling (refer to the following description regarding the ion
milling). [0067] (3) The field emission scanning electron
microscope is set to have a magnification of 1000 times and focuses
on the cut surface. [0068] (4) The field emission scanning electron
microscope is set such that obtained images have same brightness
and same contrast every time, and a back scattered electron image
(BEI image) of the cut surface is obtained. [0069] (5) A binary
image is obtained by binarizing the BEI image with a threshold
value of 175 from the image processing software (Win Roof V50
produced by Mitani Corporation). A ratio of the area of porous
portions to the entire area of the cut surface within the binary
image is defined as a porosity.
[0070] [Ion Milling]
[0071] (1) Sample Cutting
[0072] A sample of a square of 1 cm is cut from the initial sample
by a precision cutting machine.
[0073] (2) Resin Embedding
[0074] Epoxy resin is prepared, and a surface of the sample with
the film thereon is submerged into the epoxy resin, and, then, the
sample is subject to vacuum degassing.
[0075] (3) Polishing
[0076] The sample is polished by a water-resistant polishing paper
(#1000) such that a distance between an observation target portion
and a top surface of the sample is in a range from 100 .mu.m to 500
.mu.m.
[0077] The sample is polished by a water-resistant polishing paper
(#1000) such that a distance between the observation target portion
and a processed surface of the sample is about 50 .mu.m.
[0078] A base portion of the sample is polished by a
water-resistant polishing paper (#400) such that the base portion
is parallel to the top surface of the sample.
[0079] (4) Ion Beam Irradiation
[0080] The sample is set in an ion beam irradiation device, and
then, ion beams are irradiated to the observation target portion
perpendicularly from the top surface of the sample, and the cut
surface is processed.
[0081] (Conditions: an acceleration voltage of 6 [kV], a discharge
voltage of 1.5 [kV], a gas flow rate of 0.07 [cm.sup.3/min] to 0.1
[cm.sup.3/min], and a processing time of 4 hours)
[0082] Further, the film 104 has a surface roughness of the
arithmetic mean roughness (Ra) of 4.5 .mu.m or less. The particle
generation is suppressed from the film 104 having the surface
roughness in this range.
[0083] In the exemplary embodiment, the film 104 may have a
thickness ranging from 10 .mu.m to 200 .mu.m. With the film 104
having the thickness of 10 .mu.m or more, even if the film 104 is
consumed in a plasma environment, an underlying layer of the film
104 can be suppressed from being exposed. Further, with the film
104 having the thickness of 200 .mu.m or less, adhesion between the
film 104 and the underlying layer can be maintained.
[0084] In the exemplary embodiment, only the film 104, which is a
single layer, may be directly formed on the base 102. In another
exemplary embodiment, a multilayered film ML including the film 104
may be formed on the base 102, as illustrated in FIG. 2, for
example.
[0085] In the another exemplary embodiment depicted in FIG. 2, the
multilayered film ML further includes an intermediate layer 108 in
addition to the film 104. The intermediate layer 108 is made of
yttrium oxide and is formed by the thermal spraying such as
atmospheric plasma spraying. In the exemplary embodiment, the
intermediate layer 108 is formed on a clean surface of the base 102
and on a partial region of the alumite film 106 which is continuous
with the clean surface. That is, the intermediate layer 108 is not
formed on a region of the base 102 including the edge thereof.
[0086] Here, an adhesive strength of the yttrium fluoride film to
the base 102 is 8.8 MPa, and an adhesive strength of the yttrium
oxide film to the base 102 is 12.8 MPa. Accordingly, by providing
the intermediate layer 108 between the base 102 and the film 104,
the adhesive strength of the multilayered film ML to the base 102
can be improved. Further, the intermediate layer 108 may have a
porosity in the range from, for example, 3% to 10%. Furthermore,
the intermediate layer 108 may have a thickness in the range from
10 .mu.m to 200 .mu.m. With the intermediate layer 108 in such a
thickness range, the above-stated adhesive strength can be
maintained.
[0087] Moreover, the yttrium fluoride, which forms the film 104,
has a relatively low breakdown voltage. Meanwhile, the yttrium
oxide, which forms the intermediate layer 108, has a relatively
high breakdown voltage. By providing this intermediate layer 108
between the film 104 and the base 102, a breakdown voltage of the
multilayered film ML including the intermediate layer 108 and the
film 104 can be increased.
[0088] Furthermore, in the exemplary embodiment, the thicknesses of
the film 104 and the intermediate layer 108 may be equal to or
larger than 100 .mu.m. With the multilayered film ML having the
film 104 and the intermediate layer 108 in such a thickness range,
it is possible to obtain a high breakdown voltage even in a high
temperature environment.
[0089] In the exemplary embodiment, the film 104 is not formed on a
region R1 including an edge of the intermediate layer 108, but is
formed on an inner region R2 than the region R1. On the region R1
including the edge thereof, cracks of the film may be easily
created during the thermal spraying process. In view of this, the
film 104 is not formed on the region R1, and, thus, cracks of the
film 104 can be suppressed.
[0090] FIG. 3 is an enlarged cross sectional view illustrating a
part of a component for the plasma processing apparatus according
to another exemplary embodiment. A component 100A depicted in FIG.
3 may be used as the aforementioned electrode plate 34, for
example. Thus, a base 102 of the component 100A shown in FIG. 3 is
provided with a hole HL corresponding to a gas discharge hole 34a.
The hole HL has a taper shape with a width increasing from the
vicinity of an opening end thereof toward the opening end.
[0091] At the base 102 of the component 100A, an alumite film 106
is formed on a surface portion which forms the hole HL and a
partial region which is continuous with this surface portion.
Further, in this component 100A, an intermediate layer 108 is
formed on a clean surface of the base 102 and on the alumite film
106. Further, in the component 100A, the intermediate layer 108 is
extended to the inside of the hole HL. The film 104 is not formed
in the vicinity of the hole HL, i.e., on a region R1 including an
edge of the intermediate layer 108, but is formed on a flat region
R2 of the intermediate film 108. At the region R1 of the component
100A, there may easily occur cracks of the film during a thermal
spraying process. Thus, the film is not formed on the region R1,
and, thus, a damage of the film 104 can be suppressed.
[0092] Now, referring to FIG. 4A and FIG. 4B, a component according
to still another exemplary embodiment will be explained. FIG. 4A
and FIG. 4B are enlarged cross sectional views illustrating a part
of a component for the plasma processing apparatus according to
still another exemplary embodiment. In a component 100B depicted in
FIG. 4A, a multilayered film ML further includes an intermediate
layer 110. The intermediate layer 110 is provided between a film
104 and an intermediate layer 108. The intermediate layer 110 may
be formed by the thermal spraying. The intermediate layer 110 may
have a thickness in the range from, by way of example, but not
limitation, 10 .mu.m to 500 .mu.m to achieve sufficient
adhesivity.
[0093] As one example, the intermediate layer 110 is made of
yttria-stabilized zirconia (YSZ), or forsterite. The intermediate
layer 110 may be formed by the atmospheric plasma spraying method.
Here, a linear expansion coefficient of the film 104 is about
14.times.10.sup.-6K.sup.-1, and a linear expansion coefficient of
the intermediate layer 108 is about 7.3.times.10.sup.-6K.sup.-1.
Further, a linear expansion coefficient of the YSZ is
9.times.10.sup.-6K.sup.-1, and a linear expansion coefficient of
the forsterite is 10.times.10.sup.-6K.sup.-1. That is, the
intermediate layer 110 made of the YSZ or the forsterite has a
linear expansion coefficient that falls between the linear
expansion coefficient of the film 104 and the linear expansion
coefficient of the intermediate layer 108. Thus, by providing this
intermediate layer 110 between the film 104 and the intermediate
layer 108, peeling of the film 104 that might be caused by a
difference in the linear expansion coefficients between the film
104 and the intermediate layer 108 can be suppressed.
[0094] As another example, the intermediate layer 110 may be made
of a thermally sprayed alumina film or a thermally sprayed gray
alumina (alumina--about 2.5% of titania) film. By using this
intermediate layer 110, the multilayered film ML including the film
104, the intermediate layer 108 and the intermediate layer 110 and
having a high breakdown voltage is provided on the base 102.
[0095] In a component 100C depicted in FIG. 4B, a multilayered film
ML may further include an intermediate layer 112. The intermediate
layer 112 is provided between a base 102 and an intermediate layer
108. The intermediate layer 112 may have a thickness in the range
from, by way of non-limiting example, 10 .mu.m to 500 .mu.m in
order to improve the adhesivity thereof. The intermediate layer 112
may be made of a thermally sprayed alumina film or a gray alumina
(alumina-about 2.5% of titania). This intermediate layer 112 may be
formed by the atmospheric plasma spraying method. By using this
intermediate layer 112, the multilayered film ML including a film
104, the intermediate layer 108 and the intermediate layer 112 and
having a high breakdown voltage is provided on the base 102.
[0096] Now, a manufacturing method of manufacturing the component
according to the above-described various embodiments will be
explained. FIG. 5 is a flowchart for describing a manufacturing
method according to the exemplary embodiment. FIG. 6A to FIG. 7D
are diagrams illustrating a product in individual processes of the
manufacturing method of FIG. 5.
[0097] The manufacturing method PM described in FIG. 5 starts from
a process S1 (perform alumite-treatment on base). At the process
S1, an alumite-treatment (anodic oxidation) of a base 102 is
performed. At the process S1, as depicted in FIG. 6A, a mask MK1 is
prepared on the base 102. The mask MK1 is provided on the base 102
to allow only a region of the base 102 on which the
alumite-treatment will be performed to be exposed. Then, the
alumite-treatment is performed, so that an alumite film 106 is
formed, as illustrated in FIG. 6B.
[0098] Subsequently, a process S2 (perform surface conditioning on
base) is performed, as depicted in FIG. 5. At the process S2, a
surface conditioning is performed on a surface of the base 102. For
the process S2, a surface conditioning using a diamond whetstone, a
SiC whetstone, a diamond film, or the like, or a buffing surface
conditioning may be performed. Alternatively, for the surface
conditioning of the process S2, a CO.sub.2 blasting or a blasting
with alumina or SiC may be performed. At the process S2, the
surface of the base 102 is surface-controlled such that the surface
roughness (arithmetic mean roughness (Ra)) is 4.5 .mu.m or less in
a case of providing the single layer, and 5.5 .mu.m or less in a
case of providing the intermediate layer.
[0099] In a subsequent process S3 (form intermediate layer), an
intermediate layer is formed. When producing the component 100 and
the component 100A, the intermediate layer 108 is formed. When
producing the component 100B, the intermediate layer 108 and the
intermediate layer 110 are formed. When forming the component 100C,
the intermediate layer 112 and the intermediate layer 108 are
formed. When forming each intermediate layer in the process S3, the
thermal spraying is performed by using a slurry that contains
particles of a material forming each intermediate layer. For this
thermal spraying, various thermal spraying methods such as an
atmospheric plasma spraying (APS) method and a high velocity oxygen
fuel (HVOF) spraying method may be used. Furthermore, when forming
the intermediate layer 108, the slurry containing particles having
a diameter ranging from 10 .mu.m to 35 .mu.m may be used. The
slurry containing the particles of this particle size can be
prepared at a low cost.
[0100] FIG. 7A and FIG. 7B depict a product produced in the course
of forming the intermediate layer 108 of the component 100. In the
exemplary embodiment, as illustrated in FIG. 7A, a mask MK2, which
allows only a region where an intermediate layer is to be formed to
be exposed, is formed on the base 102. Then, an intermediate layer
is formed by the thermal spraying. By way of example, as
illustrated in FIG. 7B, the intermediate layer 108 is formed by the
thermal spraying.
[0101] In a subsequent process S4 (perform surface conditioning on
underlying layer), a surface conditioning is performed on the
underlying layer, which is the topmost intermediate layer. For this
process S4, a surface conditioning using a diamond whetstone, a SiC
whetstone, a diamond film, or the like, or a buffing surface
conditioning may be performed. Alternatively, for the surface
conditioning of the process S4, a CO.sub.2 blasting or a blasting
with alumina or SiC may be performed. In this process S4, the
surface of the base 102 is surface-controlled such that the surface
roughness (arithmetic mean roughness (Ra)) is 4.5 .mu.m or less.
Furthermore, when forming the film 104 directly on the base 102,
the process S3 and the process S4 may not be performed.
[0102] In a subsequent process S5 (form film), the film 104 is
formed. At the process S5, as illustrated in FIG. 7C, a mask MK3,
which allows an underlying region (for example, a region R2) on
which the film 104 is to be formed to be exposed, is formed. Then,
the film 104 is formed, as depicted in FIG. 7D, by the thermal
spraying with a slurry containing yttrium fluoride particles.
[0103] FIG. 8 is a diagram for describing a high velocity oxygen
fuel spraying method according to the exemplary embodiment. FIG. 9
is a diagram for describing an atmospheric plasma spraying method
according to the exemplary embodiment. For the thermal spraying in
the process S5, the high velocity oxygen fuel (HVOF) spraying
method depicted in FIG. 8 or the atmospheric plasma spraying (APS)
method depicted in FIG. 9 may be performed.
[0104] As shown in FIG. 8, a spraying apparatus SA1 for the HVOF
method of forming the film 104 is equipped with a spraying gun SG1
and a slurry supplying nozzle SN. The spraying gun SG1 includes a
combustion vessel unit BC forming a combustion chamber BS; a nozzle
NG1 adjacent to the combustion vessel unit BC; and an ignition
device ID. In the spraying gun SG1, a gas, which contains
high-pressure oxygen and a fuel, is supplied into the combustion
chamber BS, and the ignition device ID ignites the gas. Flame
(combustion flame) generated in the combustion chamber BS is
collected in the nozzle NG1 and jetted from the nozzle NG1. The
slurry is supplied from the nozzle SN into the jetted flame.
Accordingly, the particles in the slurry are melted or semi-melted,
and then, sprayed, in a melted or semi-meted state, onto a product
WP on which the film 104 is to be formed.
[0105] When forming the film 104 by the HVOF method, the slurry is
supplied to a position distanced apart from a tip end of the nozzle
NG1 or a positon corresponding to the tip end of the nozzle NG1 in
a direction of a central axis line AX1 of the nozzle NG1 of the
spraying gun SG1, as shown in FIG. 8. That is, a distance X from
the tip end of the nozzle NG1 to the slurry supply position is set
to be 0 mm or larger.
[0106] As depicted in FIG. 9, a spraying apparatus SA2 for the APS
method of forming the film 104 is equipped with a spraying gun SG2
and a nozzle SN configured to supply a slurry. The spraying gun SG2
includes a vessel unit PC forming a plasma generation space PS; a
nozzle NG2 adjacent to the vessel unit PC; and an electrode ET. The
vessel unit PC is made of an insulator, and the nozzle NG2 is made
of a conductor. The electrode ET is provided within the vessel unit
PC. In this spraying gun SG2, an operation gas is supplied into the
vessel unit PC, and a voltage is applied between the electrode ET
and the nozzle NG2. Accordingly, plasma of the operation gas is
generated to be jetted from the nozzle NG2. Then, the slurry is
supplied from the nozzle NG2 into the jetted plasma, so that
particles in the slurry are melted or semi-melted and then,
sprayed, in a melted or semi-melted state, onto a product WP on
which the film 104 is to be formed.
[0107] When forming the film 104 by the APS method, as depicted in
FIG. 9, the slurry is supplied to a position distanced apart from a
tip end of the nozzle NG2 or a positon corresponding to the tip end
of the nozzle NG2 in a direction of a central axis line AX1 of the
nozzle NG2 of the spraying gun SG1. That is, a distance X from the
tip end of the nozzle NG2 to the slurry supply position is set to
be 0 mm or larger.
[0108] In the process S5 using any of the HVOF method and the APS
method, the slurry may contain yttrium fluoride particles, a
dispersion medium and an organic dispersant. The dispersion medium
is water or alcohol. The yttrium fluoride particles are contained
in this slurry at a mass ratio of 5% to 40%. A diameter of each
yttrium fluoride particle is in the range from 1 .mu.m to 8 .mu.m.
Further, an average particle diameter is defined as a diameter
measured by laser diffraction/scattering method (micro-track
method).
[0109] The film 104 is formed by the above-described thermal
spraying method. Subsequently, if the mask MK2 and the mask MK3 are
removed, the component is obtained, and the manufacturing method PM
is finished.
[0110] In this manufacturing method PM, since the film 104 is
formed on the surface of the underlying layer which has undergone
through the surface conditioning on which the surface conditioning
has been performed, the surface roughness of the film 104 is
reduced. This film 104 has a small specific surface area, so that
the particle generation from the film 104 can be suppressed.
Furthermore, since the average diameter of the particles contained
in the slurry ranges from 1 .mu.m to 8 .mu.m, aggregation of the
particles is suppressed, so that the film 104 can be made uniform.
Moreover, since the average diameter of the particles contained in
the slurry is in the range from 1 .mu.m to 8 .mu.m, it is possible
to form the film having high adhesivity between the particles. In
addition, since the slurry is supplied onto the aforementioned
position, it is possible to suppress the sprayed material from
adhering to the inner wall of the nozzle of the spraying gun or the
like. As a result, a spitting can be suppressed. Thus, according to
this manufacturing method PM, a film having a low porosity and a
small specific surface area, i.e., a highly dense film 104 can be
formed. In this film 104, a little change in the surface thereof
occurs even when it is exposed to the plasma, and, thus, a
variation in process performance can be reduced. Therefore,
according to this manufacturing method PM, it is possible to form a
film capable of suppressing the particle generation.
[0111] When performing the HVOF method in the process S5 of the
exemplary embodiment, the position to which the slurry is supplied
is in the range from 0 mm to 100 mm in the direction of the central
axis line AX1 from the tip end of the nozzle NG1 of the spraying
gun SG1. That is, the distance X depicted in FIG. 8 ranges from 0
mm to 100 mm. Further, when performing the APS method in the
process S5, the position to which the slurry is supplied is in the
range from 0 mm to 30 mm in the direction of the central axis line
AX1 from the tip end of the nozzle NG2 of the spraying gun SG2.
That is, the distance X shown in FIG. 9 ranges from 0 mm to 30
mm.
[0112] Furthermore, whichever one of the HVOF method and the APS
method is selected as the spraying method in the process S5, an
angle .theta. shown in FIG. 8 and FIG. 9 is zero (0) degree, or in
the range from 45 degrees to 135 degrees. The angle .theta. is
formed between the central axis line AX2 of the nozzle SN and the
central axis line AX1 at the side of the tip end of the nozzle of
the spraying gun.
[0113] In addition, in the process S5 in the exemplary embodiment,
the product WP including the base 102 is set to have a temperature
ranging from 100.degree. C. to 300.degree. C. during the thermal
spraying process. The yttrium fluoride has a high thermal expansion
coefficient. Thus, if the sprayed yttrium fluoride particles adhere
to the surface of the underlying layer, those thermally sprayed
particles may be rapidly cooled and aggregated, so that the cracks
can occur in the film being formed. According to the exemplary
embodiment, however, since the temperature of the product WP
including the base 102 is set to be in the range from 100.degree.
C. to 300.degree. C., it is possible to suppress the cracks in the
film 104.
[0114] Further, in case of performing the HVOF method in the
process S5, an oxygen/fuel ratio is set to be a value higher than a
theoretical oxygen/fuel ratio required for the complete combustion
of the fuel. Accordingly, generation of soot caused by the
incomplete combustion can be suppressed, and introduction of the
soot into the film 104 can be suppressed.
[0115] In the above, the various exemplary embodiments have been
described. However, the exemplary embodiments are not limiting, and
various changes and modifications may be made. By way of example,
the plasma processing apparatus with the above-described
plasma-resistant components may not be limited to the capacitively
coupled plasma processing apparatus. The plasma-resistant
components may be applied to various types of plasma processing
apparatus such as an inductively coupled plasma processing
apparatus, a plasma processing apparatus that generates plasma by a
microwave, and so forth.
[0116] Below, experiments conducted to evaluate the manufacturing
method PM and the film 104 will be described.
[0117] <Evaluation of X and .theta. in Thermal Spraying in
Process S5 of Manufacturing Method PM>
[0118] Thermally sprayed yttrium fluoride films are prepared by
performing the HVOF method and the APS method, respectively, while
varying X and .theta. depicted in FIG. 8 and FIG. 9 in various
ways. To form the thermally sprayed films, the slurry containing
yttrium fluoride particles having an average diameter of 1.5 .mu.m
and a mass ratio of 35% is used. Further, in the thermal spraying
process, the temperature of the target object, i.e., the
temperature of the product including the base is set to 250.degree.
C.
[0119] Then, the produced thermally sprayed films are evaluated
based on evaluation items to be described below. In the description
of the evaluation items, the term "after the plasma process" means
a time point after the thermally sprayed film formed on the sample
is exposed to the plasma for 10 hours. Here, the plasma is
generated by placing the sample on which the thermally sprayed film
has been formed in the plasma processing apparatus 10; by supplying
a gas containing CF.sub.4, Ar and O.sub.2 into the processing
vessel 12; and by setting the high frequency power from the first
high frequency power supply 62 to 1500 W.
[0120] <Evaluation Items>
[0121] (Consumption)
[0122] A level difference between a masked region and a non-masked
region of the thermally sprayed film on the sample after the plasma
process is measured by a profiler. If the level difference
equivalent to or larger than the thickness of the thermally sprayed
film is observed, it is determined that the thermally sprayed film
has been consumed.
[0123] (Split/Crack)
[0124] When observing the appearance of the thermally sprayed film
with naked eyes, if a stripe-shaped or a mesh-shaped crack is
clearly found in the thermally sprayed film, it is evaluated as
"split presence" or "crack presence." Furthermore, When observing
the cross section of the thermally sprayed film with the SEM, if
there is found a crack that passes through the thermally sprayed
film in the thickness direction thereof, or a continuous crack
having a length of 30 .mu.m or longer, it is also evaluated as
"split presence" or "crack presence."
[0125] (Peeling)
[0126] When observing the appearance of the thermally sprayed film
with naked eyes, if the thermally sprayed film is found to be
peeled off apparently, or if a minute gap between the thermally
sprayed film and the underlying layer is found, it is determined
that the thermally sprayed film is peeled off. Further, when
observing the cross section of the thermally sprayed film with the
SEM, if a continuous minute gap having a length of 50 .mu.m or
larger between the thermally sprayed film and the underlying layer
is found, it is also evaluated that the thermally sprayed film is
peeled off.
[0127] (Adhesion Ratio)
[0128] A ratio of a weight of the thermally sprayed film to a
weight of the used particles is calculated, and when this ratio is
equal to or less than 1%, it is evaluated as "Low adhesion
ratio."
[0129] (Material Adhesion to Nozzle of Spraying Gun)
[0130] When observing an inner wall of the nozzle of the spraying
gun and an appearance in the vicinity of an outlet of the nozzle
with naked eyes, if there are observed melted particles adhering to
the spraying gun, it is determined that the particles are melt to
adhere thereto.
[0131] (Particle Evaluation)
[0132] A carbon tape is placed on the thermally sprayed film after
the plasma process, and a 26 g-weight made of
polytetrafluoroethylene is mounted on the carbon tape. Thereafter,
the weight is removed and the carbon tape is detached. Then, the
carbon tape is observed by the SEM. Further, a ratio of the area of
a transcribed region to the entire area of the carbon tape on the
SEM image is calculated, and this ratio is defined as a
transcription ratio. If the transcription ratio of the thermally
sprayed film as the evaluation target is larger than a
transcription ratio of a thermally sprayed film created by the APS
method with the slurry containing yttrium fluoride particles having
an average diameter of 50 .mu.m while setting X=5 mm and .theta.=90
degrees, it is concluded that the thermally sprayed film as the
evaluation target has "Particle defect."
[0133] Table 1 shows values of X and .theta., and evaluation
results for the thermally sprayed film that is produced. As for the
evaluation results, "Good" implies that the thermally sprayed film
exhibits favorable characteristics for all of the above-described
evaluation items.
TABLE-US-00001 TABLE 1 Thermal Spraying Method X(mm)
.theta.(degree) Evaluation Result HVOF 130 90 Particle defect 100
45 Good 100 90 Good 100 135 Good 50 90 Good 0 45 Good 0 90 Good 0
135 Good -30 90 Melt particles adhesion to the inner wall of the
nozzle 50 30 Low adhesion ratio 50 45 Good 50 135 Good 50 150 Melt
particles adhesion to the vicinity of nozzle outlet 0 0 Good -30 0
Melt particles adhesion to the inner wall of the nozzle APS 40 90
Particle defect 30 135 Good 30 90 Good 30 45 Good 15 90 Good 0 135
Good 0 90 Good 0 45 Good -20 90 Melt particles adhesion to the
inner wall of the nozzle 15 30 Low adhesion ratio 15 45 Good 15 135
Good 15 150 Melt particles adhesion to the vicinity of nozzle
outlet 0 0 Good -30 0 Melt particles adhesion to the inner wall of
the nozzle
[0134] As shown in Table 1, in the HVOF method, the "Particle
defect" is found when X is 130 mm. Further, in the HVOF method,
when X has a negative value, it is found that the particles are
melted to adhere to the inner wall of the nozzle of the spraying
gun. In addition, in the HVOF method, it is found that a favorable
thermally sprayed film can be formed when X is in the range from 0
mm to 100 mm. Furthermore, in the HVOF method, when .theta. is 30
degrees, the "Low adhesion ratio" is found, and when .theta. is 150
degrees, melted particles are found to adhere to the vicinity of
the nozzle outlet of the spraying gun. Furthermore, when .theta. is
in the range from 45 degrees to 135 degrees, it is proved that a
favorable thermally sprayed film can be formed.
[0135] Further, in the APS method, the "Particle defect" is found
when X is 40 mm. When X has a negative value, it is found that the
particles are melted to adhere to the inner wall of the nozzle of
the spraying gun. In addition, it is found that a favorable
thermally sprayed film can be formed when X is in the range from 0
mm to 30 mm. Furthermore, in the APS method, when .theta. is 30
degrees, the "Low adhesion ratio" is found, and when .theta. is 150
degrees, melt particles are found to adhere to the vicinity of the
nozzle outlet of the spraying gun. Furthermore, when .theta. is in
the range from 45 degrees to 135 degrees, it is found that a
favorable thermally sprayed film can be formed.
[0136] <Evaluation Regarding Temperature of Base During Thermal
Spraying of Process S5 in Manufacturing Method PM>
[0137] Thermally sprayed yttrium fluoride films are prepared by
performing the HVOF method and the APS method, respectively, while
varying the temperature of the product including the base in
various ways. To form the thermally sprayed film, the slurry
containing yttrium fluoride particles having an average diameter of
1.5 .mu.m and a mass ratio of 35% is used. Further, in the HVOF
method, X and .theta. are set to be X=50 mm and .theta.=90 degrees.
In the APS method, X and .theta. are set to be X=15 mm and
.theta.=90 degrees. Then, the produced thermally sprayed films are
evaluated in view of the crack, which is one of the aforementioned
evaluation items, and, also, in view of base deformation. Table 2
provides evaluation results.
TABLE-US-00002 TABLE 2 Temperature of Base (.degree. C.) Evaluation
Result 350 No crack but large base deformation 300 No crack, no
base deformation 250 No crack, no base deformation 100 No crack, no
base deformation 48 Crack presence
[0138] As can be seen from Table 2, when the temperature of the
product including the base is 48.degree. C., the crack is generated
in the thermally sprayed film, and when the temperature is
350.degree. C., a relatively large base deformation is generated.
Further, when the temperature is in the range form 100.degree. C.
to 300.degree. C., neither the crack nor the base deformation are
generated. This result proves that if the temperature of the base
is set to be in the range from 100.degree. C. to 300.degree. C.,
the crack in the thermally sprayed film and the base deformation
can be both suppressed.
[0139] <Evaluation Regarding Diameter of Particle During Slurry
During Thermal Spraying in Process S5 in the Manufacturing Method
PM>
[0140] Thermally sprayed yttrium fluoride films are prepared by
performing the HVOF method and the APS method, respectively, while
varying an average diameter of yttrium fluoride particles in
various ways. To form the thermally sprayed film, the slurry
containing yttrium fluoride particles at a mass ratio of 35% is
used. Further, in the HVOF method, X and .theta. are set to be X=50
mm and .theta.=90 degrees. In the APS method, X and .theta. are set
to be X=15 mm and .theta.=90 degrees. Further, the temperature of
the product including the base is set to 250.degree. C. Then, the
produced thermally sprayed films are evaluated based on the
aforementioned evaluation items. Also, the porosity and the
thickness of each of the produced thermally sprayed films are
calculated. Table 3 provides evaluation results.
TABLE-US-00003 TABLE 3 Average Particle Film Diameter Porosity
Thickness Evaluation (.mu.m) (%) (.mu.m) Result 15 4.4 130 Particle
defect 8 4 130 Good 4.2 2.5 120 Good 1.5 1.8 130 Good 1 0.2 130
Good 0.82 1.5 120 Crack presence 1.5 1.8 250 Peeled 1.5 1.8 200
Good 1.5 1.8 10 Good 1.5 1.8 5 Consumed
[0141] As can be seen from Table 3, when the average diameter of
the particles in the slurry is 15 .mu.m, the "Particle defect" is
found, and when the average diameter of the particles is 0.82
.mu.m, the crack in the thermally sprayed film is found. Further,
when the average diameter of the particles is in the range from 1
.mu.m to 8 .mu.m, favorable thermally sprayed films are formed. In
view of this, it is found that if the average diameter of the
particles in the slurry is in the range from 1 .mu.m to 8 .mu.m, a
favorable thermally sprayed film can be formed. Furthermore, when
the porosity of the thermally sprayed film is 4.4%, the "Particle
defect" is found, and when the porosity is 4% or less, no particle
defect is found. In view of this, it is found that if the porosity
is 4% or less, the particle generation can be suppressed. In
addition, when the thickness of the thermally sprayed film is 5
.mu.m, it is found that the consumption of the thermally sprayed
film after the plasma process is large. Moreover, the peeling of
the thermally sprayed film is found when its thickness is 250
.mu.m. From this, it is also found that if the thickness of the
thermally sprayed film is in the range from 10 .mu.m to 200 .mu.m,
the thermally sprayed film can be maintained even if it is consumed
by the plasma process, and, also, the peeling of the thermally
sprayed film can be suppressed.
[0142] <Evaluation Regrading Surface Roughness>
[0143] Thermally sprayed yttrium fluoride films having different
surface roughness are prepared while adjusting surface roughness of
the base. The HVOF method is performed as the thermal spraying.
Further, the slurry containing yttrium fluoride particles having an
average diameter of 1.5 .mu.m and a mass ratio of 35% is used in
the thermal spraying. In the HVOF method, X and .theta. are set to
be X=50 mm and .theta.=90 degrees. Then, among the aforementioned
evaluation items, the particle evaluation is made. When Ra is 4.8
.mu.m, it is determined that there is "Particle defect", and when
Ra is 4.5 .mu.m and 3.5 .mu.m, respectively, no particle defect is
observed. In view of this result, it is found that if the thermally
sprayed film has the surface roughness of Ra=4.5 .mu.m or less, the
particle generation therefrom can be suppressed.
[0144] <Evaluation Regarding Breakdown Voltage>
[0145] Single-layered films made of yttrium fluoride are formed on
the base while varying thicknesses of the films in various ways.
Furthermore, a multilayered film, which includes an intermediate
layer of yttrium oxide having a thickness of 100 .mu.m and an
yttrium fluoride film having a thickness of 100 .mu.m, is formed on
the base. Then, the breakdown voltages of the single-layered films
and the multilayered film are measured while varying the
temperature. FIG. 10 shows the breakdown voltages of the
single-layered films. In FIG. 10, a vertical axis represents the
breakdown voltage, and upper-side values presented along a
horizontal axis indicate the thickness .mu.m of the single-layered
films and lower-side values presented along the horizontal axis
represent the temperature (.degree. C.) of the films when the
breakdown voltage is measured. Further, `RT` represents the room
temperature. Moreover, FIG. 11 presents the breakdown voltage of
the multilayered films. In FIG. 11, a vertical axis represents the
breakdown voltage, and values presented along a horizontal axis
indicate the temperature (.degree. C.) of the multilayered film
when the breakdown voltage is measured.
[0146] As can be seen from FIG. 10, the yttrium fluoride
single-layered films show higher breakdown voltages as they have
larger thicknesses. In the high temperature environment, however,
the breakdown voltage is found to be decreased. As can be seen from
FIG. 11, it is found that by providing the intermediate layer made
of yttrium oxide having the thickness of 100 .mu.m between the film
and the base, it is possible to suppress the breakdown voltage of
the multilayered film from being reduced even in the high
temperature environment.
[0147] <Evaluation Regarding Number of Particles Generated by
Plasma Process in Plasma Processing Apparatus Equipped with
Electrode Plate 34 Having Film and Intermediate Layer>
[0148] There is prepared an electrode plate 34 (refer to the
component 100A of FIG. 3) including an intermediate layer, which is
made of yttrium oxide and has a thickness of 150 .mu.m, formed on
an aluminum base; and a film, which is made of yttrium fluoride and
has a thickness of 50 .mu.m, a surface roughness (arithmetic mean
roughness (Ra)) of 1.43 .mu.m and a porosity of 2.39% (hereinafter,
referred to as "Film 1"), formed on the intermediate layer.
Further, a plasma processing apparatus 10 is provided with the
electrode plate 34 (hereinafter, referred to as "plasma processing
apparatus 10 having Film 1"). A wafer is mounted on the mounting
table PD of the plasma processing apparatus 10, and the plasma
process is performed. In the plasma process, a gaseous mixture
containing a C.sub.4F.sub.8 gas, a C.sub.4F.sub.6 gas, a CF.sub.4
gas, an Ar gas, an O.sub.2 gas, and a CH.sub.4 gas is supplied into
the processing vessel 12 at a total flow rate of 425 sccm, and a
total power of the high frequency power from the first high
frequency power supply 62 and the high frequency power from the
second high frequency power supply 64 is set to be 5000 W. Then, a
relationship between a processing time of the plasma process and
the number of particles generated on the wafer is obtained.
Further, in the measurement of the particles, the number of
particles having a size of 45 nm or larger is measured by using
Surfscan SP2 produced by KLA-Tencor.
[0149] Further, there is also prepared an electrode plate 34 (refer
to the component 100A of FIG. 3) including an intermediate layer,
which is made of yttrium oxide and has a thickness of 150 .mu.m,
formed on an aluminum base; and a film, which is made of yttrium
fluoride and has a thickness of 50 .mu.m, a surface roughness
(arithmetic mean roughness (Ra)) of 5.48 .mu.m and a porosity of
5.21% (hereinafter, referred to as "Film 2"), formed on the
intermediate layer. Further, a plasma processing apparatus 10 is
provided with the rode plate 34 (hereinafter, referred to as
"plasma processing apparatus 10 having Film 2"). A wafer is mounted
on the mounting table PD of the plasma processing apparatus 10, and
the same plasma process as that performed in case of using the
plasma processing having Film 1 is performed. Then, as in the case
of using the plasma processing apparatus 10 having Film 1, a
relationship between a processing time of the plasma process and
the number of particles generated on the wafer is obtained.
[0150] FIG. 12 is a graph showing a relationship between the
processing time of the plasma process and the number of the
particles. In FIG. 12, a horizontal axis represents the processing
time h of the plasma process, and a vertical axis indicates the
number of particles. Further, a solid line on the graph indicates a
regression line of the number of the particles generated at each of
a plurality of processing times when using the plasma processing
apparatus 10 having Film 1, and a dashed line on the graph
indicates a regression line of the number of the particles
generated at each of multiple processing times when using the
plasma processing apparatus 10 having Film 2. As shown in FIG. 12,
the number of the particles generated by the plasma process in the
plasma processing apparatus 10 having Film 1 is found to be
considerably reduced, as compared to the number of the particles
generated by the plasma process in the plasma processing apparatus
10 having Film 2. That is, it is found that the particle generation
by the plasma process can be suppressed, according to the plasma
processing apparatus including the electrode plate 34 provided with
the film having the porosity of 4% or less and the surface
roughness (arithmetic mean roughness (Ra)) of 4.5 .mu.m or
less.
[0151] From the foregoing, it will be appreciated that various
embodiments of the present disclosure have been described herein
for purposes of illustration, and that various modifications may be
made without departing from the scope and spirit of the present
disclosure. Accordingly, the various embodiments disclosed herein
are not intended to be limiting.
* * * * *