U.S. patent application number 11/665230 was filed with the patent office on 2008-02-07 for corrosion-resistant member and method for manufacture thereof.
This patent application is currently assigned to NIHON CERATEC CO., LTD.. Invention is credited to Hiromichi Otaki, Makoto Sakamaki, Toshiya Umeki.
Application Number | 20080032115 11/665230 |
Document ID | / |
Family ID | 36202847 |
Filed Date | 2008-02-07 |
United States Patent
Application |
20080032115 |
Kind Code |
A1 |
Umeki; Toshiya ; et
al. |
February 7, 2008 |
Corrosion-Resistant Member and Method for Manufacture Thereof
Abstract
A corrosion-resistant member used in a corrosive environment
includes a substrate, and a ceramic sprayed film, which covers a
part or all of the substrate surface and has relative density of
80% or greater. Maximum diameter of voids existing in the ceramic
sprayed film surface is 25 .mu.m or less. This corrosion-resistant
member is obtained by using Y.sub.2O.sub.3 as a material having a
bulk density of at least 1.5 g/cm.sup.3 and dried to a moisture
content of 1 mass percent or less and spraying plasma on the
substrate with an output power of 40 to 110 kW by a spraying device
including two anode torches.
Inventors: |
Umeki; Toshiya; (Miyagi,
JP) ; Sakamaki; Makoto; (Miyagi, JP) ; Otaki;
Hiromichi; (Miyagi, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
220 Fifth Avenue
16TH Floor
NEW YORK
NY
10001-7708
US
|
Assignee: |
NIHON CERATEC CO., LTD.
24-1, Ake-Dori 3-chome, Izumi-ku,Sendai-city
Miyagi
JP
981-3292
|
Family ID: |
36202847 |
Appl. No.: |
11/665230 |
Filed: |
September 30, 2005 |
PCT Filed: |
September 30, 2005 |
PCT NO: |
PCT/JP05/18593 |
371 Date: |
April 12, 2007 |
Current U.S.
Class: |
428/312.8 ;
427/541; 427/576 |
Current CPC
Class: |
C23C 4/134 20160101;
C23C 4/11 20160101; Y10T 428/24997 20150401 |
Class at
Publication: |
428/312.8 ;
427/541; 427/576 |
International
Class: |
C23C 4/10 20060101
C23C004/10; C23C 4/12 20060101 C23C004/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 18, 2004 |
JP |
2004-302889 |
Claims
1. A corrosion-resistant member used in a corrosive environment,
the corrosion-resistant member comprising a substrate and a ceramic
sprayed film, which covers a part or all of the substrate surface
and has a relative density of 80% or greater, wherein the ceramic
sprayed film has a thickness of 50 to 500 .mu.m, and a surface
prepared such that voids existing therein have a maximum diameter
of 25 .mu.m or less.
2. The corrosion-resistant member of claim 1, wherein the ceramic
sprayed film is a film made of Y.sub.2O.sub.3, and has an etching
rate of 5 nm/min or less when plasma etching is performed under
conditions of a flow rate of 50 mL/min, an output power of 1,000 W,
and a pressure of 6.7 Pa using a mixed gas made of 80% CF.sub.4 and
20% O.sub.2 by a parallel plate type RIE apparatus with
inter-electrode gap of 100 mm.
3. The corrosion-resistant member of claim 2, wherein the
corrosion-resistant member is obtained by using Y.sub.2O.sub.3
having a bulk density of at least 1.5 g/cm.sup.3 and a moisture
content of 1 mass percent or less as material for the ceramic
sprayed film and spraying plasma on the substrate with an output
power of 40 to 110 kW by a spraying device including two anode
torches.
4. The corrosion-resistant member of claim 1, wherein the ceramic
sprayed film is a film made of Al.sub.2O.sub.3, and has an etching
rate of 20 nm/min or less when plasma etching is performed under
conditions of a flow rate of 50 mL/min, an output power of 1,000 W,
and a pressure of 6.7 Pa using a mixed gas made of 80% CF.sub.4 and
20% O.sub.2 by a parallel plate type RIE apparatus with
inter-electrode gap of 100 mm.
5. The corrosion-resistant member of claim 4, wherein the
corrosion-resistant member is obtained by using Al.sub.2O.sub.3
having a bulk density of at least 1.0 g/cm.sup.3 and a moisture
content of 1 mass percent or less as material for the ceramic
sprayed film and spraying plasma on the substrate with an output
power of 40 to 110 kW by a spraying device including two anode
torches.
6. A method for manufacture of a corrosion-resistant member by
covering a substrate surface with a Y.sub.2O.sub.3 film through
plasma thermal spraying, the method comprising: a drying step of
drying material having a bulk density of at least 1.5 g/cm.sup.3
until a moisture content is 1 percent or less by mass; and a plasma
thermal spraying step of spraying the material after drying on a
substrate surface with an output power of 40 to 110 kW by a
spraying device including two anode torches, and forming a
Y.sub.2O.sub.3 film having a relative density of 80% or greater, a
thickness of 50 to 500 .mu.m, and a surface prepared such that
voids existing therein have a maximum diameter of 25 .mu.m or
less.
7. A method for manufacture of a corrosion-resistant member by
covering a substrate surface with an Al.sub.2O.sub.3 film through
plasma thermal spraying, the method comprising: a drying step of
drying material having a bulk density of at least 1.0 g/cm.sup.3
until a moisture content is 1 percent or less by mass; and a plasma
thermal spraying step of spraying the material after drying on a
substrate surface with an output power of 40 to 110 kW by a
spraying-device including two anode torches, and forming an
Al.sub.2O.sub.3 film having a relative density of 80% or greater, a
thickness of 50 to 500 .mu.m, and a surface prepared such that
voids existing therein have a maximum diameter of 25 .mu.m or less.
Description
TECHNICAL FIELD
[0001] The present invention relates to a corrosion-resistant
member used in a corrosive atmosphere such as a corrosive plasma
gas environment, and a method for manufacture thereof. More
specifically, it relates to a corrosion-resistant member having
excellent resistance to halogen plasma gas or halogen corrosive gas
used in a semiconductor device manufacturing process or a liquid
crystal device manufacturing process, for example, and a method for
manufacture thereof.
BACKGROUND ART
[0002] In manufacture of semiconductor devices or liquid crystal
devices, silica glass and a ceramic have been often used in the
past as material for members such as chambers, susceptors, and
clamp rings used in a highly chemically corrosive environment.
[0003] In recent years, the size of substrates for manufacturing
semiconductor devices or liquid crystal devices has been increased
in view of cost reduction. For example, it has been required to
accommodate a wafer of 12 inch size for semiconductor wafers, or a
substrate of larger than 1 m square size for liquid crystal
devices. As a result, enlargement of manufacturing apparatus is
also required. However, there are limits to use of conventional
silica glass or a ceramic for large sized parts in terms of
strength and rigidity. Therefore, a member including a metal
substrate covered by a film of a corrosion-resistant material such
as a ceramic has come into use.
[0004] A technology for allowing formation of a larger
corrosion-resistant member has been proposed (e.g., Japanese Patent
Gazette No. 3510993, Japanese Patent Application Laid-open No.
2004-10981). According to the technology, a film is formed through
thermal spraying using a corrosion-resistant material such as
alumina or a rare-earth oxide such as Y.sub.2O.sub.3, for
example.
[0005] When forming a corrosion-resistant film by spraying,
generation of voids in the film is unavoidable, and the voids tend
to become larger than in a bulk ceramic. Particularly, a
Y.sub.2O.sub.3 sprayed film has higher corrosion resistance than
other sprayed films such as an Al.sub.2O.sub.3 sprayed film.
However, since the melting point of Y.sub.2O.sub.3 or material is
high and is thus difficult to melt, the voids in a sprayed film
composition will be larger than in the Al.sub.2O.sub.3 sprayed
film.
[0006] Even before now, voids on a sprayed film surface are
considered a contributing factor to reducing corrosion resistance
of the sprayed film. However, according to study by the present
inventors, it is revealed that size of each void greatly
contributes to corrosion resistance more than the existence of
voids in the sprayed film surface.
[0007] In other words, when a sprayed film including large voids is
exposed to halogen plasma gas or halogen corrosive gas, the voids
serve as starting points for void corrosion, resulting in easy
development of corrosion. Furthermore, where voids are larger than
a certain size, locally low adhesive strength regions are easily
generated at an interface between the substrate and the sprayed
film, so handling of such a member during manufacture such as
mounting of the member becomes difficult, and film peeling also
occurs easily. However, according to conventional spraying
technology, voids in the sprayed film surface are given attention,
but there is no consideration given to controlling the size
thereof.
DISCLOSURE OF INVENTION
[0008] An objective of the present invention is to provide a
corrosion-resistant member having voids controlled in size and also
having excellent corrosion resistance and adhesiveness to a
substrate, and a method for manufacture thereof.
[0009] In view of the aforementioned actual condition, through
devoted research, the inventors have concentrated on developing a
material that has small voids existing in a sprayed film surface,
excellent resistance to halogen plasma gas or halogen corrosive
gas, and excellent adhesive strength between a substrate and a
sprayed film. As a result, it has been found that size of voids in
the sprayed film depends on manufacturing conditions thereof, and
that void size can be controlled to be less than a certain size
through selection of the manufacturing conditions, thereby
providing a sprayed film with excellent corrosion resistance and
adhesiveness to a substrate. The present invention has been made on
the basis of the findings.
[0010] According to a first aspect of the present invention, there
is provided a corrosion-resistant member used in a corrosive
environment including a substrate and a ceramic sprayed film, which
covers a part or all of the substrate surface and has relative
density of 80% or greater. The ceramic sprayed film has a thickness
of 50 to 500 .mu.m, and a surface prepared such that voids existing
therein have a maximum diameter of 25 .mu.m or less
[0011] Furthermore, the ceramic sprayed film may be a film made of
Y.sub.2O.sub.3, and have an etching rate of 5 nm/min or less when
plasma etching is performed under conditions of a flow rate of 50
mL/min, output power of 1,000 W, and a pressure of 6.7 Pa using a
mixed gas made of 80% CF.sub.4 and 20% O.sub.2 by a parallel plate
type RIE apparatus with inter-electrode gap of 100 mm. In this
case, the corrosion-resistant member is obtained by using
Y.sub.2O.sub.3 having a bulk density of at least 1.5 g/cm.sup.3 and
a moisture content of 1 mass percent or less as material for the
ceramic sprayed film and spraying plasma on the substrate with an
output power of 40 to 110 kW by a spraying device including two
anode torches.
[0012] Alternatively, the ceramic sprayed film may be a film made
of Al.sub.2O.sub.3, and have an etching rate of 20 nm/min or less
when plasma etching is performed under conditions of a flow rate of
50 mL/min, output power of 1,000 W, and a pressure of 6.7 Pa using
a mixed gas made of 80% CF.sub.4 and 20% O.sub.2 by a parallel
plate type RIE apparatus with inter-electrode gap of 100 mm. In
this case, the corrosion-resistant member is obtained by using
Al.sub.2O.sub.3 having a bulk density of at least 1.0 g/cm.sup.3
and a moisture content of 1 mass percent or less as material for
the ceramic sprayed film and spraying plasma on the substrate with
an output power of 40 to 110 kW by a spraying device including two
anode torches.
[0013] According to a second aspect of the present invention, there
is provided a method for manufacture of corrosion-resistant member
by covering a substrate surface with a Y.sub.2O.sub.3 film through
plasma thermal spraying. The method includes: a drying step of
drying material having a bulk density of at least 1.5 g/cm.sup.3
until a moisture content is 1 percent or less by mass; and a plasma
thermal spraying step of spraying the material after drying on a
substrate surface with an output power of 40 to 110 kW by a
spraying device including two anode torches, and forming a
Y.sub.2O.sub.3 film having a relative density of 80% or greater, a
thickness of 50 to 500 .mu.m, and a surface prepared such that
voids existing therein have a maximum diameter of 25 .mu.m or
less.
[0014] According to a third aspect of the present invention, there
is provided a method for manufacture of corrosion-resistant member
by covering a substrate surface with an Al.sub.2O.sub.3 film
through plasma thermal spraying. The method includes: a drying step
of drying material having a bulk density of at least 1.0 g/cm.sup.3
until a moisture content is 1 percent or less by mass; and a plasma
thermal spraying step of spraying the material after drying on a
substrate surface with an output power of 40 to 110 kW by a
spraying device including two anode torches, and forming an
Al.sub.2O.sub.3 film having a relative density of 80% or greater, a
thickness of 50 to 500 .mu.m, and a surface prepared such that
voids existing therein have a maximum diameter of 25 .mu.m or
less.
[0015] According to the present invention, since the sprayed film
obtained by adjusting moisture content and bulk density of the
material and spraying with output power of 40 to 110 kW by a
spraying device including two anode torches separated from one
another is controlled such that the maximum diameter of voids
(hereafter referred to as "maximum void diameter") existing in the
surface is 25 .mu.m or less, starting points for corrosion
decrease, and etching rate at the time of plasma exposure is
low.
[0016] Furthermore, by keeping the maximum void diameter in the
sprayed film surface at 25 .mu.m or less, locally low adhesive
strength regions decrease at the interface with the substrate,
allowing adhesive strength degradation before and after plasma
irradiation and adhesive strength degradation due to purified water
ultrasonic cleaning after plasma irradiation to be under 30%.
Therefore, use of the corrosion-resistant. member according to the
present invention as a member within a chamber or the like in
semiconductor manufacturing processes and liquid crystal
manufacturing processes allows prevention of particle generation
due to corrosion, and extension of the lifetime of the member.
Furthermore, this allows reduction in manufacturing costs for
semiconductor devices and liquid crystal devices, and improvement
in productivity due to reduction in frequency of part
replacement.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a cross sectional view schematically showing a
device for forming a sprayed film on a corrosion-resistant member
of the present invention; and
[0018] FIG. 2 is a cross sectional view schematically showing a
configuration of a RIE apparatus used for etching the
corrosion-resistant member.
BEST MODE FOR CARRYING OUT THE INVENTION
[0019] A preferred embodiment according to the present invention is
described forthwith.
[0020] A corrosion-resistant member according to the present
invention is used in a corrosive environment for a plasma process
or the like using a corrosive gas. For example, it may be used as
materials for a chamber of a plasma apparatus used during film
formation or etching of a semiconductor wafer or a substrate for
liquid crystal devices. Further, it may be used as materials for a
gas distributor, a liner, a susceptor, a clamp ring, a sleeve, or a
door, which are members within the chamber.
[0021] The corrosion-resistant member includes at least a substrate
and a ceramic sprayed film, which covers a part or all of the
substrate. While material of the substrate is not limited, it may
be formed of a metal such as stainless steel or aluminum, glass, a
ceramic, or a ceramic composite, for example. The ceramic sprayed
film is a film covering the surface of the substrate and at least a
region exposed to a corrosive atmosphere. The film has a relative
density of 80% or greater, and a maximum void diameter of 25 .mu.m
or less in the film surface.
[0022] Where the relative density of the ceramic sprayed film is
low, corrosion resistance and plasma resistance decrease,
degasification from the corrosion-resistant member increases, and
degree of vacuum in the chamber does not increase, thereby raising
running cost. Accordingly, relative density is preferably 80% or
greater, and in order to prevent reduction in chip yield due to
particle generation, relative density of 85% or greater is more
preferable.
[0023] Where void diameter in the ceramic sprayed film surface
becomes large, irregular portions in which plasma easily gathers
increase, and thus local plasma corrosion becomes easy to develop.
It can be considered that void size (void diameter) more than
number or gross area of voids profoundly contributes to the
tendency to bring about plasma corrosion. In other words, as an
extremely simplified example, rather than a case where many small
voids exist in the sprayed film surface, a case where a single or
few voids larger than a certain size exist is greater cause for
significant reduction in plasma resistance of the sprayed film.
According to the inventors' knowledge, maximum diameter of voids
existing in the sprayed film surface has important implications in
terms of affecting plasma resistance. As shown in working examples
and comparative examples to be described later, it is confirmed
that voids with a diameter of 25 .mu.m or greater compared to voids
with a diameter of 25 .mu.m or less reduce adhesiveness to the
sprayed film, easily cause corrosion, and further cause particle
contamination.
[0024] According to the conventional sprayed films, maximum void
diameter in the sprayed film surface is given attention, but there
is no consideration given to control thereof. However, where the
maximum void diameter exceeds 25 .mu.m, depth of the voids also
deepens in compliance with the diameter. Therefore, locally low
adhesive strength regions are generated at the interface with the
substrate.
[0025] Furthermore, where the maximum void diameter is large, edges
thereof are also formed long in compliance with the diameter. Since
regions closer to void edges are shaved off and detached more
easily in a plasma environment, voids greater than 25 .mu.m in
diameter with long edges and a high depth ratio to film thickness
easily cause detachment in the plasma environment and tend to
generate particles.
[0026] Moreover, when repeatedly exposed to the plasma environment,
the voids gradually enlarge and depth thereof also increases.
Ultimately, in this case, deficient regions may develop locally in
the sprayed film, resulting in an exposed substrate surface, which
may give rise to corrosion.
[0027] Because of this, a sprayed film including even a single void
greater than 25 .mu.m in diameter in the surface significantly
reduces in corrosion resistance.
[0028] On the other hand, where the maximum void diameter is 25
.mu.m or less, there is hardly any influence on adhesive strength
of the sprayed film, and the voids do not become large enough such
that deficiencies are generated in the sprayed film under normal
use conditions, so the corrosion resistance can be maintained.
[0029] Furthermore, since particles having gotten into the voids
are difficult to remove through cleaning, this contaminates the
chamber during processes, and may lead to reduction in chip yield.
However, if the maximum void diameter is 15 .mu.m or less,
probability of particles getting into the voids may significantly
lower, thereby preventing particle contamination emanating from
intrusion of particles into the voids.
[0030] Therefore, a maximum void diameter of 25 .mu.m or less is
preferable, 15 .mu.m or less is even more preferable. Note that
"maximum void diameter" may be determined based on the diameter of
the largest void on the surface in which ten fields of view are
observed using a scanning microscope at a 500-fold magnification
after the sprayed film surface has been polished.
[0031] Thickness of the sprayed film of the corrosion-resistant
member is preferably 50 to 500 .mu.m, more preferably 100 to 300
.mu.m, for example. Where the film is too thick, thermal history
increases due to repeated film formation, and micro cracks
developing on the interface between the substrate and the sprayed
film increase, thereby facilitating detachment of the sprayed film.
Where the film is too thin, since through-holes in the sprayed film
increase, the interface between the substrate and the sprayed film
is easy to corrode, thereby facilitating detachment of the sprayed
film.
[0032] Furthermore, by keeping the maximum void diameter at 25
.mu.m or less, reduction in number of through-holes is possible
even where the film is relatively thin. Corrosion at the interface
between the substrate and the sprayed film is prevented, and
detachment of the sprayed film is prevented from occurring, thereby
allowing improved durability. In other words, suppression of the
maximum void diameter to 25 .mu.m or less allows formation of a
sprayed film having sufficient durability even with a thickness of
50 .mu.m, for example.
[0033] In the case where the ceramic sprayed film including voids
with a maximum diameter of 25 .mu.m or less is a Y.sub.2O.sub.3
film, it has an etching resistance property of an etching rate of 5
nm/min or less when it has been subjected to plasma etching under
predetermined conditions such as at a flow rate of 50 mL/min, power
of 1,000 W, and pressure of 6.7 Pa (50 mTorr) using a mixed gas
made of 80% CF.sub.4 and 20% O.sub.2, for example, by a parallel
plate type RIE apparatus with inter-electrode gap of 100 mm. Since
the Y.sub.2O.sub.3 film having an etching rate of 5 nm/min in the
above-mentioned conditions is barely etched even through plasma
irradiation, particle contamination can be prevented from
occurring, lifetime of the corrosion-resistant member extends, and
frequency of member replacement reduces, thereby improving
productivity of semiconductor devices and liquid crystal
devices.
[0034] Furthermore, in the case where the ceramic sprayed film
including voids with a maximum diameter of 25 .mu.m or less is an
Al.sub.2O.sub.3 film, it has an etching resistance property of an
etching rate of 20 nm/min or less when it has been subjected to
plasma etching under predetermined conditions such as at a flow
rate of 50 mL/min, power of 1,000 W, and pressure of 6.7 Pa (50
mTorr) using a mixed gas made of 80% CF.sub.4 and 20% O.sub.2, for
example, by a parallel plate type RIE apparatus with
inter-electrode gap of 100 mm. Since the Al.sub.2O.sub.3 film
having an etching rate of 20 nm/min in the above-mentioned
conditions is only slightly etched through plasma irradiation,
particle contamination is prevented from occurring, and a
sufficient lifetime of the corrosion-resistant member is provided,
thereby contributing to high productivity of semiconductor devices
and liquid crystal devices.
[0035] A manufacturing method for the corrosion-resistant member
according to the present invention is described forthwith while
referencing the drawings.
[0036] In order to form a sprayed film as described above, a
spraying device including a cathode torch and two anode torches
separated from one another is used with the present invention.
Since use of two such separated anode torches allows introduction
of material to a plasma arc, which is at a very high temperature,
ceramic material may be completely melted, thereby achieving a
desired sprayed film. An anode integrated spraying device has
difficulty in complete melting a ceramic material, because it
cannot introduce the material to the plasma arc, structurally.
[0037] When spraying a ceramic material, use of an oxygen (O)
contained plasma gas is preferable. Oxygen contained plasma gas may
be formed by supplying oxygen gas (O.sub.2), air, or a mixed gas
thereof, for example. Use of such an oxygen contained plasma gas in
this manner prevents defects and coloration from occurring through
reduction of a ceramic when melting the ceramic at a high
temperature.
[0038] A specific structure of the spraying device including a
cathode torch and two anode torches separated from one another will
be described now. FIG. 1 is a cross sectional view schematically
showing an example of such a spraying device. This spraying device
includes a device main unit 1 having a spray particle outlet 1a, a
cathode torch 2 provided on the opposite side to the spray particle
outlet 1a of the device main unit 1, and two anode torches 3a and
3b respectively supported by supporting members 4a and 4b on both
sides of the device main unit 1.
[0039] Ar gas is supplied to the tip of the cathode torch 2 via an
Ar gas supply pipe 11 and an Ar gas lead-in path 11a, generating an
arc while preventing oxidation of the torch (electrode). An
accelerator nozzle 5 is provided on the downstream side of the
cathode torch 2, and the arc generated at the cathode torch 2
accelerates to generate a plasma arc 40. Air or oxygen gas from an
air supply pipe 12 via an air lead-in path 12a is supplied to an
arc generated at the cathode torch 2, and the plasma arc 40
generated from the accelerator nozzle 5 becomes oxygen contained
plasma gas.
[0040] Ceramic powder or spray material powder is introduced into
the plasma arc 40 generating region from a material feed hopper not
shown in the drawing via a material supply pipe 13, and this
material powder is completely melted to form spray particles. While
complete melting of the material powder is possible in the same way
even if the material powder is supplied to the tip of the plasma
arc 40, it is preferable to supply the powder to the plasma arc 40
generating region since it is at a higher temperature.
[0041] Ar gas is supplied to the tip of the anode torch 3a via an
Ar gas supply pipe 21a and Ar gas lead-in paths 22a and 23a, an arc
is generated while preventing oxidation of the torch (electrode),
and a plasma arc 41a extends perpendicular to the plasma arc 40
projected out from the cathode torch 2.
[0042] Ar gas is also supplied to the tip of the anode torch 3b via
an Ar gas supply pipe 21b and Ar gas lead-in paths 22b and 23b,
resulting in generation of an arc while preventing oxidation of the
torch (electrode), and a plasma arc 41b extends perpendicular to
the plasma arc 40 projected out from the cathode torch 2. A plasma
jet 40a develops at the confluence of the plasma arcs 40, 41a, and
41b. In the vicinity of the spray particle outlet 1a of the device
main unit 1, air is supplied to the plasma jet 40a from air pipes
24a and 24b via respective air lead-in paths 25a and 25b and heat
not contributing to melting in the plasma jet 40a is removed.
[0043] Auxiliary power supplies 32a and 32b functioning as
high-frequency starters for starting arc generation, and DC main
power supplies 31a and 31b functioning as energy resources for
sustaining arcs are connected to the cathode torch 2 and the anode
torches 3a and 3b, respectively. Note that the auxiliary power
supplies 32a and 32b and the DC main power supplies 31a and 31b are
controlled by a control unit not shown in the drawing.
[0044] A cooling jacket 14 is provided to surround the cathode
torch 2 and the accelerator nozzle 5 for protecting them from high
temperatures, and cooling jackets 26a and 26b are provided to
surround the anode torches 3a and 3b.
[0045] In such a spraying device, spray particles 51 carried by the
plasma jet 40a hit a substrate 53, thereby forming a sprayed film
52.
[0046] Where spray output power is too low, melting of the material
does not progress, thereby increasing the maximum void diameter. On
the other hand, where spray output power is too high, defects are
generated through ceramic reduction. Accordingly, it is preferable
to make the spray output power 40 kW or greater and 110 kW or
less.
[0047] As an advantage of using an anode separated plasma thermal
spraying device as shown in FIG. 1, this device is capable of
completely melting the ceramic of a sprayed film material, since
the material is put into a plasma arc generating region, which is
at a very high temperature. On the other hand, with the anode
integrated spraying device, since material cannot be supplied to
the plasma arc generating region structurally, melting of the
material may be insufficient.
[0048] Furthermore, in the case of the anode separated plasma
thermal spraying device having separated anodes, output power for a
single anode may be reduced, and high output power is possible.
Accordingly, it facilitates uniform melting of the material, and
improves denseness of the sprayed film, thereby providing voids
having a reduced maximum diameter. However, with the anode
integrated spraying device, where the output power for the anode is
great, there is fear of the spraying device being damaged since it
cannot endure high output power.
[0049] Furthermore, in the case of a flame spraying device, melting
of the material does not progress due to a low flame temperature,
and formation of a sprayed film having uniform, fine, small voids
is difficult.
[0050] It is preferable that the ceramic material to be sprayed is
a powder or granular having a fixed bulk density. Where the bulk
density of the material is low, the material has a light weight.
Therefore, the material cannot get into the plasma flame and a film
is insufficiently melted and formed, resulting in difficult
formation of a dense film as well as difficult control of void
diameter. Furthermore, where material density is low and pores
exist in the material, they enter the sprayed film and make it
difficult to form a dense sprayed film. Therefore, the bulk density
of the material for Y.sub.2O.sub.3 is preferably 1.5 g/cm.sup.3 or
greater, more preferably 1.8 g/cm.sup.3 or greater, with a desired
upper limit of 3.0 g/cm.sub.3. Furthermore, the bulk density for
Al.sub.2O.sub.3 is preferably 1.0 g/cm.sup.3 or greater, more
preferably 1.2 g/cm.sup.3 or greater, with a desired upper limit of
2.4 g/cm.sub.3.
[0051] When drying of the ceramic material used for spraying is
insufficient, the material may be clogged in a material feeder due
to moisture adsorbed to the material, supply becomes unstable, and
melting of the material also becomes insufficient, thereby
facilitating generation of large voids in the film. Therefore, it
is preferable to use material that is pre-dried until moisture
content is approximately 1 percent or less by mass. Furthermore,
since probability of voids being generated during spraying is high
due to moisture evaporation from the material, moisture content of
the material is preferably approximately 5 percent or less by mass.
Heating at a temperature of 70.degree. C. or higher, for example,
for 12 hours or more as a guide for when drying the material allows
reduction in the moisture content down to approximately 1 percent
or less by mass. Heating at a temperature of 250.degree. C. or
higher for 12 hours or more allows reduction in the moisture
content down to approximately 0.5% mass or less.
[0052] It should be noted that an ordinary commercially available
powder material may be used on the condition that bulk density and
dryness are set to the above given conditions. As needed, the
material may be granulated so as to improve flowability of the
powder.
[0053] The substrate 53 may be subjected to surface processing such
as blasting. It is preferable that the blasted substrate is
sufficiently cleaned to completely remove blast materials,
shavings, and the like deposited on the surface. Adhesion of the
film decreases when such debris is left on the substrate surface,
and is thus unfavorable.
[0054] As described above, by adjusting bulk density and moisture
content of the material and completely melting the ceramic material
when spraying in such a spraying device as shown in FIG. 1, a film
having a relative density of 80% or higher, a maximum void diameter
of 25 .mu.m or less, few remaining pores, excellent adhesion and
mechanical resistance to the substrate, and high etching resistance
can be formed.
[0055] Working examples and comparative examples are given
hereafter to further describe the present invention in detail.
However, the present invention is not limited thereto.
WORKING EXAMPLES 1 TO 8, COMPARATIVE EXAMPLES 1 TO 9
[0056] An Al substrate (JIS 6061) surface roughened to a surface
roughness Ra greater than 4 .mu.m was prepared, different types of
spraying devices were used, and a Y.sub.2O.sub.3 sprayed film was
formed as a test plate. A spraying device including two separated
anode torches (see FIG. 1), a spraying device having an integrated
anode torch, and a high velocity oxygen fuel thermal spraying
(HVOF) device were used as the spraying devices.
[0057] Sprayed film manufacturing conditions: drying temperature,
drying time, moisture content, and bulk density of material
(granular), and sprayed film thickness and spray output power (15
to 110 kW), were varied as shown in Tables 1 and 2, and were called
Working Examples 1 to 8 and Comparative Examples 1 to 9. In the
respective working examples and comparative examples, film
formation property, relative density, porosity, maximum void
diameter, etching rate, adhesive strength degradation due to plasma
irradiation, and adhesive strength degradation due to purified
water ultrasonic cleaning after plasma irradiation were
respectively evaluated by the following methods. Results thereof
are shown in Tables 1 and 2 collectively.
[Film Formation Property]
[0058] Film formation property was evaluated by confirming film
peeling after spraying. Samples with no film peeling after spraying
were denoted by ".largecircle.", samples with partial film peeling
by ".DELTA.", and samples with complete film peeling after spraying
by "X".
[Relative Density]
[0059] Relative density was evaluated by peeling off just the
sprayed film from the substrate and measuring bulk density using
the Archimedes method and was then provided by (bulk
density)/(theoretical density). Porosity was calculated based on
the relative density.
[Maximum Void Size]
[0060] Maximum void diameter was defined by the diameter of the
largest void found when ten fields of view in the surface were
observed using a scanning microscope at a 500-fold magnification
after the sprayed film surface was polished.
[Etching Rate]
[0061] Etching rate was calculated by polishing the surface of the
test plate, masking a part of the polished surface with polyimide
tape, conducting reactive ion etching (RIE), and then measuring
difference in height of regions covered by the mask and regions not
covered by the mask.
[0062] A structure of a RIE apparatus used in this etching test is
schematically shown in FIG. 2. This RIE apparatus 101 is configured
as a parallel plate type RIE apparatus in which a pair of electrode
plates faces each other vertically. The RIE apparatus 101 has a
susceptor 103, which is a mounting table for a test plate TP within
a chamber 102 and functions as a lower electrode. In this test, the
susceptor 103 having a length L2 of 480 mm was used.
[0063] A showerhead 105 functioning as an upper electrode facing
the susceptor 103 in parallel is provided over the susceptor 103.
Interval (inter-electrode gap L1) between the susceptor 103 and the
showerhead 105 is adjustable by a lifting mechanism not shown in
the drawing. A gas supply pipe 108 is connected to the showerhead
105, and the gas supply pipe 108 is split on the upstream side of a
valve 109 and connected to a CF.sub.4 gas supply source 110 and an
O.sub.2 gas supply source 111. Pipes from these gas supply sources
are respectively provided with a flow adjustment means not shown in
the drawing, which is structured capable of adjusting flow of
CF.sub.4 gas and O.sub.2 gas as etching gases. The etching gases
reach a gas supply chamber 107 within the showerhead 105 via the
gas supply pipe 108, and are then discharged evenly from gas
discharge openings 106.
[0064] A high-frequency power source 112 is connected to the
susceptor 103, which functions as a lower electrode, via a
converter not shown in the drawing, and this high-frequency power
source 112 may supply high-frequency power of 13.56 MHz, for
example, to the susceptor 103.
[0065] An exhaust outlet 104 is formed at the bottom of the chamber
102, and is structured capable of vacuuming inside the chamber 102
to a predetermined reduced-pressure atmosphere using a vacuum pump
not shown in the drawing.
[0066] With the RIE apparatus 101 with the above-given structure,
the test plate TP was mounted on the susceptor 103, the
inter-electrode gap L1 was adjusted to 100 mm, and the chamber 102
was evacuated to create a high vacuum state of 6.7 Pa (50 mTorr).
Afterwards, the etching gases were supplied to the chamber 102 in a
mixing ratio CF.sub.4:O.sub.2=80:20 while maintaining a flow of 50
mL/min (sccm). In this state, a high-frequency electric field was
generated by applying high-frequency power of 1,000 W to the
susceptor 103 as a lower electrode, the etching gases were
transformed into plasma, and the surface of the test plate was then
etched. Etching was conducted for two hours.
[Adhesive Strength Degradation]
[0067] Adhesive strength before and after performing plasma
processing under the aforementioned conditions was measured for
five test pieces (F25 mm) at a pulling rate of 1 mm/min. The
average value thereof was calculated, and adhesive strength
degradation due to plasma irradiation was then calculated by the
following equation: Adhesive strength degradation (%)=((adhesive
strength after plasma irradiation)/(adhesive strength before plasma
irradiation)).times.100
[0068] This adhesive strength degradation due to plasma irradiation
is preferably no greater than 30% since there is a possibility that
the sprayed film will peel off during the process where the value
thereof is high.
[0069] Adhesive strength after performing plasma processing under
the aforementioned conditions and before and after cleaning using
purified water ultrasonic waves was measured for five test pieces
(F25 mm) at a pulling rate of 1 mm/min. The average value thereof
was calculated, and adhesive strength degradation due to the
purified water ultrasonic waves was then calculated by the
following equation: Adhesive strength degradation (%)=((adhesive
strength after purified water ultrasonic cleaning)/(adhesive
strength before purified water ultrasonic cleaning)).times.100
[0070] This adhesive strength degradation due to the purified water
ultrasonic waves is preferably no greater than 30% since there is a
possibility that the sprayed film will peel off during the process
where the value thereof is high. TABLE-US-00001 TABLE 1 Material
Material Material Material Output Drying Drying Moisture Bulk Film
Film Spraying Power Temperature Time Content Density Thickness
Formation No Device (kW) (.degree. C.) (h) (%) (g/cm.sup.3) (.mu.m)
Property.sup..asterisk-pseud.1 Working 1 Anode 110 250 12 0.1 2.0
220 .largecircle. Examples Separated- Type 2 Anode 95 150 14 0.3
2.3 280 .largecircle. Separated- Type 3 Anode 65 100 12 0.2 2.0 160
.largecircle. Separated- Type 4 Anode 60 100 12 0.3 1.8 200
.largecircle. Separated- Type 5 Anode 40 250 12 0.2 2.1 110
.largecircle. Separated- Type 6 Anode 80 70 14 0.8 1.5 50
.largecircle. Separated- Type 7 Anode 40 150 12 0.3 1.6 360
.largecircle. Separated- Type 8 Anode 50 100 14 0.4 1.6 480
.largecircle. Separated- Type Adhesive Strength Degradation (%)
Maximum After Purified Relative Void Etching After Water Density
Porosity Diameter.sup..asterisk-pseud.2 Rate.sup..asterisk-pseud.3
Plasma Ultrasonic No (%) (%) (.mu.m) (nm/min)
Irradiation.sub..asterisk-pseud.4 Cleaning.sup..asterisk-pseud.5
Working 1 93 7 9 2 12 16 Examples 2 92 8 11 2 15 19 3 91 9 14 2 14
18 4 91 9 9 2 13 15 5 90 10 12 3 14 16 6 88 12 15 3 21 24 7 86 14
20 4 23 29 8 87 13 16 3 24 27 .sup..asterisk-pseud.1Sample allowing
film formation is denoted by .largecircle., sample with partial
peeling during film formation by .DELTA., and sample with no film
formation by X. .sup..asterisk-pseud.2Maximum void diameter when
ten fields of view in the sprayed surface were observed after
polishing .sup..asterisk-pseud.3Gas: CF4 + 20% O2, Output power:
1,000 kW, gas flow: 50 mL/min(sccm), pressure: 6.7 Pa(50 mTorr),
processing time: 2 hours .sub..asterisk-pseud.4Adhesive strength
degradation after etching was conducted under plasma conditions in
.asterisk-pseud.3 .sup..asterisk-pseud.5Adhesive strength
degradation after step of drying at 70.degree. C. for 1 hour was
repeated thirty times after cleaning at 40 kHz for 10 min
[0071] TABLE-US-00002 TABLE 2 Material Material Material Material
Output Drying Drying Moisture Bulk Film Film Spraying Power
Temperature Time Content Density Thickness Formation No Device (kW)
(.degree. C.) (h) (%) (g/cm3) (.mu.m)
Property.sup..asterisk-pseud.1 Comparative 1 Anode 65 Non 0 1.8 0.9
90 .largecircle. Examples Separated- Type 2 Anode 55 Non 0 1.7 2.0
260 .largecircle. Separated- Type 3 Anode 40 250 12 0.2 0.9 350
.largecircle. Separated- Type 4 Anode 15 250 14 0.1 2.0 160 .DELTA.
Separated- Type 5 Anode 60 250 14 0.1 1.9 240 .largecircle.
Integrated- Type 6 Anode 40 150 12 0.3 2.0 160 .largecircle.
Integrated- Type 7 Anode 35 100 14 0.3 2.0 280 .DELTA. Integrated-
Type 8 Anode 20 250 14 0.1 2.0 -- X Integrated- Type 9 HVOF 40 250
14 0.1 2.1 280 .largecircle. Spraying Adhesive Strength Degradation
(%) Maximum After Purified Relative Void Etching After Water
Density Porosity Diameter.sup..asterisk-pseud.2
Rate.sup..asterisk-pseud.3 Plasma Ultrasonic No (%) (%) (.mu.m)
(nm/min) Irradiation.sub..asterisk-pseud.4
Cleaning.sup..asterisk-pseud.5 Comparative 1 81 19 28 7 37 62
Examples 2 78 22 29 7 53 80 3 80 20 30 8 62 Peeled 4 77 23 32 9 --
-- 5 90 10 29 7 27 63 6 80 20 31 8 43 Peeled 7 78 22 30 8 -- -- 8
-- -- -- -- -- -- 9 76 24 11 7 12 14 .sup..asterisk-pseud.1Sample
allowing film formation is denoted by .largecircle., sample with
partial peeling during film formation by .DELTA., and sample with
no film formation by X. .sup..asterisk-pseud.2Maximum void diameter
when ten fields of view in the sprayed surface were observed after
polishing .sup..asterisk-pseud.3Gas: CF4 + 20% O2, Output power:
1,000 kW, gas flow: 50 mL/min(sccm), pressure: 6.7 Pa(50 mTorr),
processing time: 2 hours .sub..asterisk-pseud.4Adhesive strength
degradation after etching was conducted under plasma conditions in
.asterisk-pseud.3 .sup..asterisk-pseud.5Adhesive strength
degradation after step of drying at 70.degree. C. for 1 hour was
repeated thirty times after cleaning at 40 kHz for 10 min
[0072] As is evident from Tables 1 and 2, with the Y.sub.2O.sub.3
sprayed film sprayed by the spraying device including two separated
anode torches in Working Examples 1 to 8, relative density was 80%
or greater and maximum void diameter was 25 .mu.m or less in all
cases. From this, it was confirmed that starting points for
corrosion due to plasma decreased, and the etching rate using
CF.sub.4+O.sub.2 plasma was 5 .mu.m/min or less.
[0073] Particularly, in Working Examples 1 to 5, a sprayed film
having a thickness of 100 to 300 .mu.m was formed by heating
material having a bulk density of 1.8 g/cm.sup.3 or greater at a
temperature of 100.degree. C. or higher for at least twelve hours,
drying it until the moisture content was 0.5 percent or less by
mass, and spraying it with an output power of 40 kW to 110 kW using
the spraying device including two anode torches. Consequently, it
was confirmed that melting of the material progressed, so relative
density was 90% or greater, maximum void diameter was 15 .mu.m or
less, and etching rate was 3 .mu.m/min or less.
[0074] Furthermore, in Working Examples 1 to 5, since voids 25
.mu.m or greater in diameter, which became starting points for
corrosion due to plasma, did not exist, adhesive strength
degradation before and after plasma irradiation was below 20%
without generation of locally low adhesive strength regions between
the sprayed film and the substrate. Furthermore, it was confirmed
that there was little corrosion at the interface between the
substrate and the sprayed film after plasma irradiation, and
adhesive strength degradation by purified water ultrasonic cleaning
after plasma irradiation was also below 20%.
[0075] Meanwhile, in Comparative Examples 1 and 2 where material
drying was not performed, maximum void diameter exceeded 25 .mu.m,
etching rate was high, and adhesive strength degradation was
prominent.
[0076] Furthermore, in Comparative Example 3 using a material
having a low bulk density, maximum void diameter was large, etching
rate was high, adhesive strength degradation was prominent, and
film peeling occurred during an adhesive strength test after
purified water ultrasonic cleaning. In Comparative Example 4 where
spray output power was low, film formation property was poor, and
etching rate was high.
[0077] In Comparative Examples 5 to 7 using the anode integrated
spraying device, maximum void diameter was large, etching rate was
high, and adhesive strength degradation was prominent. In
Comparative Example 8 using the anode integrated spraying device
and using material having low spray output power and high bulk
density, film formation was impossible.
[0078] In Comparative Example 9 using the HVOF (high velocity
oxygen fuel thermal spraying) device, maximum void diameter was
small, relative density was low, and etching rate was high.
WORKING EXAMPLES 9 TO 16, COMPARATIVE EXAMPLES 10 TO 18
[0079] An Al substrate (JIS 6061) surface roughened to a surface
roughness Ra greater than 4 .mu.m was prepared, different types of
spraying devices were used, and an Al.sub.2O.sub.3 sprayed film was
formed and used as a test plate. The same spraying devices as
mentioned above were used.
[0080] Film manufacturing conditions: drying temperature, drying
time, moisture content, bulk density of material (granular),
sprayed film thickness, and spray output (15 to 110 kW), were
varied as shown in Tables 3 and 4, and were called Working Examples
9 to 16 and Comparative Examples 10 to 18. In the respective
working examples and comparative examples, film formation property,
porosity, relative density, maximum void diameter, etching rate,
adhesive strength degradation due to plasma irradiation, and
adhesive strength degradation due to purified water ultrasonic
cleaning after plasma irradiation were respectively evaluated by
the same standards as in Working Example 1 and the other examples
by the following methods. Results thereof are shown in Tables 3 and
4 collectively.
[0081] As is evident from Tables 3 and 4, with the Al.sub.2O.sub.3
sprayed film sprayed by the spraying device including two separated
anode torches in Working Examples 9 to 16, relative density was 80%
or greater and maximum void diameter was 25 .mu.m or less in all
cases. From this, it was confirmed that starting points for plasma
corrosion decreased, and the etching rate using CF.sub.4+O.sub.2
plasma was 20 .mu.m/min or less.
[0082] Particularly, in Working Examples 9 to 13, a sprayed film
having a thickness of 100 to 300 .mu.m was formed by heating
material having a bulk density of 1.2 g/cm.sup.3 or greater at a
temperature of 100.degree. C. or higher for at least twelve hours,
drying it until the moisture content was 0.5 percent or less by
mass, and spraying it with output power of 40 kW to 110 kW using
the spraying device including two anode torches. Consequently, it
was confirmed that melting of the material progressed, relative
density was 90% or greater, maximum void diameter was 15 .mu.m or
less, and etching rate was 15 .mu.m/min or less.
[0083] Furthermore, in Working Examples 9 to 13, since voids 25
.mu.m or greater in diameter, which became starting points for
corrosion due to plasma, did not exist, adhesive strength
degradation before and after plasma irradiation was below 20%
without generation of locally low adhesive strength regions between
the sprayed film and the substrate. Furthermore, it was confirmed
that there was little corrosion at the interface between the
substrate and the sprayed film after plasma irradiation, and
adhesive strength degradation after purified water ultrasonic
cleaning after plasma irradiation was also below 20%.
[0084] Meanwhile, in Comparative Examples 10 and 11 where material
drying was not performed, etching rate was high and adhesive
strength degradation was prominent.
[0085] Furthermore, in Comparative Example 12 using a material
having a low bulk density, maximum void diameter was large, etching
rate was high, adhesive strength degradation was prominent, and
film peeling occurred during an adhesive strength test after
purified water ultrasonic cleaning. In Comparative Example 13 where
spray output power was low, film formation property was poor, and
etching rate was high.
[0086] In Comparative Examples 14 and 15 using the anode integrated
spraying device, maximum void diameter was large, etching rate was
high, and adhesive strength degradation was prominent. In
Comparative Examples 16 and 17 using the anode integrated spraying
device and using material having relatively low spray output power
and high bulk density, film formation was impossible. In
Comparative Example 18 using the HVOF (high velocity oxygen fuel
thermal spraying) device, maximum void diameter was small and
etching rate was high. TABLE-US-00003 TABLE 3 Material Material
Material Material Output Drying Drying Moisture Bulk Film Film
Spraying Power Temperature Time Content Density Thickness Formation
No Device (kW) (.degree. C.) (h) (%) (g/cm3) (.mu.m)
Property.sup..asterisk-pseud.1 Working 9 Anode 110 200 12 0.1 1.3
150 .largecircle. Examples Separated- Type 10 Anode 95 100 18 0.3
1.2 270 .largecircle. Separated- Type 11 Anode 65 100 18 0.4 1.3
210 .largecircle. Separated- Type 12 Anode 60 150 18 0.2 1.5 130
.largecircle. Separated- Type 13 Anode 40 200 12 0.2 1.5 210
.largecircle. Separated- Type 14 Anode 70 70 18 0.6 1.0 460
.largecircle. Separated- Type 15 Anode 65 70 12 0.8 1.1 180
.largecircle. Separated- Type 16 Anode 50 100 12 0.5 1.1 60
.largecircle. Separated- Type Adhesive Strength Degradation (%)
Maximum After Purified Relative Void Etching After Water Density
Porosity Diameter.sup..asterisk-pseud.2 Rate.sup..asterisk-pseud.3
Plasma Ultrasonic No (%) (%) (.mu.m) (nm/min)
Irradiation.sub..asterisk-pseud.4 Cleaning.sup..asterisk-pseud.5
Working 9 93 7 6 12 6 9 Examples 10 91 9 8 13 9 14 11 91 10 9 15 8
16 12 91 9 9 13 10 15 13 90 10 12 14 8 16 14 88 12 14 17 22 25 15
86 14 17 14 21 28 16 83 17 18 17 25 28 .sup..asterisk-pseud.1Sample
allowing film formation is denoted by .largecircle., sample with
partial peeling during film formation by .DELTA., and sample with
no film formation by X. .sup..asterisk-pseud.2Maximum void diameter
when ten fields of view in the sprayed surface were observed after
polishing .sup..asterisk-pseud.3Gas: CF4 + 20% O2, Output power:
1,000 kw, gas flow: 50 mL/min(sccm), pressure: 6.7 Pa(50 mTorr),
processing time: 2 hours .sub..asterisk-pseud.4Adhesive strength
degradation after etching was conducted under plasma conditions in
.asterisk-pseud.3 .sup..asterisk-pseud.5Adhesive strength
degradation after step of drying at 70.degree. C. for 1 hour was
repeated thirty times after cleaning at 40 kHz for 10 min
[0087] TABLE-US-00004 TABLE 4 Material Material Material Material
Output Drying Drying Moisture Bulk Film Film Spraying Power
Temperature Time Content Density Thickness Formation No Device (kW)
(.degree. C.) (h) (%) (g/cm3) (.mu.m)
Property.sup..asterisk-pseud.1 Comparative 10 Anode 60 Non 0 1.7
0.7 210 .DELTA. Examples Separated- Type 11 Anode 40 Non 0 1.5 1.3
250 .largecircle. Separated- Type 12 Anode 40 100 18 0.5 0.8 80
.largecircle. Separated- Type 13 Anode 15 250 12 0.2 1.4 230
.DELTA. Separated- Type 14 Anode 60 250 18 0.1 1.5 200
.largecircle. Integrated- Type 15 Anode 40 250 12 0.1 1.3 460
.largecircle. Integrated- Type 16 Anode 40 70 18 0.5 1.2 -- X
Integrated- Type 17 Anode 30 100 12 0.4 1.3 -- X Integrated- Type
18 HVOF 40 250 18 0.1 1.2 290 .largecircle. Spraying Adhesive
Strength Degradation (%) Maximum After Purified Relative Void
Etching After Water Density Porosity Diameter.sup..asterisk-pseud.2
Rate.sup..asterisk-pseud.3 Plasma Ultrasonic No (%) (%) (.mu.m)
(nm/min) Irradiation.sub..asterisk-pseud.4
Cleaning.sup..asterisk-pseud.5 Comparative 10 79 11 27 23 -- --
Examples 11 78 22 30 27 43 56 12 82 18 28 25 39 64 13 77 23 31 29
-- -- 14 91 9 27 27 35 42 15 75 25 28 30 54 72 16 -- -- -- -- -- --
17 -- -- -- -- -- -- 18 82 18 11 28 32 39
.sup..asterisk-pseud.1Sample allowing film formation is denoted by
.largecircle., sample with partial peeling during film formation by
.DELTA., and sample with no film formation by X.
.sup..asterisk-pseud.2Maximum void diameter when ten fields of view
in the sprayed surface were observed after polishing
.sup..asterisk-pseud.3Gas: CF4 + 20% O2, Output power: 1.000 kW,
gas flow: 50 mL/min(sccm), pressure: 6.7 Pa(50 mTorr), processing
time: 2 hours .sub..asterisk-pseud.4Adhesive strength degradation
alter etching was conducted under plasma conditions in
.asterisk-pseud.3 .sup..asterisk-pseud.5Adhesive strength
degradation after step of drying at 70.degree. C. for 1 hour was
repeated thirty times after cleaning at 40 kHz for 10 min
INDUSTRIAL APPLICABILITY
[0088] The corrosion-resistant member according to the present
invention is applicable preferably in manufacturing processes for
semiconductor devices and liquid crystal devices, for example.
* * * * *