U.S. patent application number 14/471535 was filed with the patent office on 2015-03-05 for coating material for thermal spray coating, method for preparing the same, and method for coating with the same.
The applicant listed for this patent is KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY. Invention is credited to Kyeong Ho BAIK, eun young CHOI, Hoon JEONG, Yu Chan KIM, Hyun Kwang SEOK.
Application Number | 20150064358 14/471535 |
Document ID | / |
Family ID | 52583612 |
Filed Date | 2015-03-05 |
United States Patent
Application |
20150064358 |
Kind Code |
A1 |
SEOK; Hyun Kwang ; et
al. |
March 5, 2015 |
COATING MATERIAL FOR THERMAL SPRAY COATING, METHOD FOR PREPARING
THE SAME, AND METHOD FOR COATING WITH THE SAME
Abstract
A coating material for a thermal spray coating having corrosion
resistance and low reactivity, a preparation method thereof, and a
coating method thereof are provided. The coating material for
thermal spray coating has a composition of
Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to 0.99).
Inventors: |
SEOK; Hyun Kwang; (Seoul,
KR) ; KIM; Yu Chan; (Goyang-si, KR) ; CHOI;
eun young; (Busan, KR) ; BAIK; Kyeong Ho;
(Daejeon, KR) ; JEONG; Hoon; (Chungcheongbuk-do,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY |
Seoul |
|
KR |
|
|
Family ID: |
52583612 |
Appl. No.: |
14/471535 |
Filed: |
August 28, 2014 |
Current U.S.
Class: |
427/453 ;
106/286.6 |
Current CPC
Class: |
C23C 4/137 20160101;
C23C 4/134 20160101; C23C 4/11 20160101 |
Class at
Publication: |
427/453 ;
106/286.6 |
International
Class: |
C23C 4/10 20060101
C23C004/10; C23C 4/12 20060101 C23C004/12 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2013 |
KR |
10-2013-0102570 |
Claims
1. A coating material for thermal spray coating having a
composition of Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to
0.99).
2. The coating material for thermal spray coating of claim 1,
wherein x is 0.1 to 0.5.
3. The coating material for thermal spray coating of claim 1,
wherein the coating material includes a powder having a diameter of
1 to 200 .mu.m.
4. A method for preparing a coating material for thermal spray
coating, the method comprising: mixing a MgO powder having a
diameter of 0.1 to 30 .mu.m and a Y.sub.2O.sub.3 powder having a
diameter of 0.1 to 30 .mu.m to prepare a material having a
composition of Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to
0.99); and spraying and drying the material to prepare a
synthesized coating material for thermal spray coating.
5. The method of claim 4, wherein x is 0.1 to 0.5.
6. The method of claim 4, further comprising subjecting the coating
material for thermal spray coating to a thermal treatment at 900 to
1500.degree. C.
7. A method for coating with a coating material for thermal spray
coating, the method comprising: providing a coating material for
thermal spray coating having a composition of
Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to 0.99); injecting
the coating material for thermal spray coating toward a plasma jet,
followed by heating; and depositing the coating material for
thermal spray coating in a completely molten or semi-solid state on
a surface of a base metal to form a coating film.
8. The method of claim 7, wherein x is 0.1 to 0.5.
9. The method of claim 7, wherein in the forming of the coating
film, the base metal is a chamber of vacuum plasma equipment or a
part inside the chamber.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of
Korean Patent Application No. 10-2013-0102570 filed in the Korean
Intellectual Property Office on Aug. 28, 2013, the entire contents
of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] (a) Field of the Invention
[0003] The present invention relates to a coating material for
thermal spray coating, a method for preparing the same, and a
method for coating with the same. More particularly, the present
invention relates to a coating material for thermal spray coating
having corrosion resistance and low activity, a method for
preparing the same, and a method for coating with the same.
[0004] (b) Description of the Related Art
[0005] Vacuum plasma equipment is widely used in process fields for
realizing semiconductor devices or other ultrafine patterns. Vacuum
plasma equipment includes plasma enhanced chemical vapor deposition
(PECVD) equipment, sputtering equipment, dry etching equipment,
etc. Since the vacuum plasma equipment generates high-temperature
plasma to etch semiconductor devices or realize ultrafine patterns,
chambers and internal parts thereof are easily damaged. Particular
elements and contaminating particles are generated from surfaces of
the chambers and parts thereof, and thus are very likely to
contaminate the inside of the chamber.
[0006] Particularly, since a reactive gas, such as a Cl or F
species, is injected into the plasma etching equipment under the
plasma atmosphere, the inside of the chamber or the internal parts
thereof are exposed to a very corrosive environment. The corrosion
primarily causes damage to the chamber and the internal parts
thereof, and secondarily generates contaminating materials and
particles, bringing about an increased failure rate of production
goods and deteriorated product quality. The materials for the
vacuum plasma chamber and the internal parts thereof are selected
in consideration of many characteristics including corrosion
resistance, processability, ease of manufacture, price, insulating
properties, and the like. In general, metal materials, such as
stainless alloys, aluminum and alloys thereof, and titanium and
alloys thereof, and ceramic materials, such as SiO.sub.2, Si, and
Al.sub.2O.sub.3, are used.
[0007] In thermal spray coating, hybrid ceramic materials are used
to form a protection film. Thermal spray coating is a technique in
which a metal or ceramic powder is injected to a high-temperature
heat source and heated, and is then deposited in a completely
molten or semi-solid phase on a surface of a base metal to form a
coating film. Thermal spray coating techniques include plasma
thermal spray coating, high velocity oxygen fuel (HVOF) coating,
etc., depending on the kind of heat source. An Al.sub.2O.sub.3 or
Y.sub.2O.sub.3 ceramic material is commercially used as a coating
material for thermal spray coating.
[0008] The above information disclosed in this Background section
is only for enhancement of understanding of the background of the
invention and therefore it may contain information that does not
form the prior art that is already known in this country to a
person of ordinary skill in the art.
SUMMARY OF THE INVENTION
[0009] A coating material for thermal spray coating having
advantages of improving corrosion resistance to plasma under a
plasma atmosphere containing a reactive gas such as a Cl or F
species, and suppressing and minimizing formation of ultrafine
reaction products is provided. Also, a method for preparing the
foregoing coating material for thermal spray coating is provided.
Further, a method for coating with the foregoing coating material
for thermal spray coating is provided.
[0010] An exemplary embodiment of the present invention provides a
coating material for thermal spray coating having a composition of
Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to 0.99). More
preferably, x may be 0.1 to 0.5. The coating material may include a
powder having a diameter of 1 to 200 .mu.m.
[0011] Another embodiment of the present invention provides a
method for preparing a coating material for thermal spray coating,
the method including: mixing a MgO powder having a diameter of 0.1
to 30 .mu.m and a Y.sub.2O.sub.3 powder having a diameter of 0.1 to
30 .mu.m to prepare a material having a composition of
Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to 0.99); and
spraying and drying the material to prepare a synthesized coating
material for thermal spray coating. Here, x may be 0.1 to 0.5. The
method may further include subjecting the coating material for
thermal spray coating to a thermal treatment at 900 to 1500.degree.
C.
[0012] Yet another embodiment of the present invention provides a
method for coating with a coating material for thermal spray
coating, the method including: providing a coating material for
thermal spray coating having a composition of
Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to 0.99); injecting
the coating material for thermal spray coating toward a plasma jet,
followed by heating; and depositing the coating material for
thermal spray coating in a completely molten or semi-solid state on
a surface of a base metal to form a coating film. More preferably,
x may be 0.1 to 0.5. In the forming of the coating film, the base
metal may be a chamber of vacuum plasma equipment or a part inside
the chamber.
[0013] According to an embodiment of the present invention, a
coating film having improved corrosion resistance can be formed on
the internal parts of the semiconductor equipment, thereby
improving the lifespan of the internal parts of the semiconductor
equipment. In addition, a coating material having improved
corrosion resistance under the plasma atmosphere containing a
reactive gas such as a Cl or F species can be prepared. Further,
unlike the conventional art, the present invention can prevent the
formation of ultrafine reaction products in the plasma atmosphere
containing a reactive gas such as a Cl or F species, thereby
preventing damage to the inner wall of the semiconductor equipment
or contamination of goods manufactured therefrom.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic flowchart showing a method for
preparing a coating material for thermal spray coating and a method
for coating with a coating material for thermal spray according to
an embodiment of the present invention.
[0015] FIG. 2 shows scanning electron microscopic images
illustrating Mg--Y--O based materials for thermal spray coating
prepared according to Experimental Examples 1 to 5 of the present
invention.
[0016] FIG. 3 shows X-ray diffraction graphs illustrating Mg--Y--O
based materials for thermal spray coating prepared according to
Experimental Examples 1 to 5 of the present invention.
[0017] FIG. 4 shows scanning electron microscopic images obtained
by observing polished surfaces of Mg--Y--O based coatings formed by
a thermal spray coating process according to Experimental Examples
1 to 4 of the present invention.
[0018] FIG. 5 shows graphs obtained by analyzing a coating formed
according to Experimental Example 1 of the present invention using
an energy dispersive X-ray spectroscopy (EDX) system.
[0019] FIG. 6 shows X-ray diffraction graphs illustrating coatings
formed according to Experimental Examples 1 to 4 of the present
invention
[0020] FIG. 7 shows scanning electron microscopic images of etched
surfaces before and after a corrosion resistance test on coatings
formed according to Experimental Examples 1 to 4.
[0021] FIG. 8 is a graph illustrating etching rates of coatings
formed according to Experimental Examples 1 to 4 and comparative
examples 1 to 4 of the present invention.
[0022] FIG. 9 shows scanning electron microscopic images
illustrating exposed surfaces of coatings formed according to
Experimental Examples 1 to 4 of the present invention.
[0023] FIG. 10 is an image showing a state in which a large crude
reaction product generated during a manufacturing process is
dropped on a circuit.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0024] It will be understood that when an element is referred to as
being "on" another element, it can be directly on another element
or intervening elements may be present therebetween. In contrast,
when an element is referred to as being "directly on" another
element, there are no intervening elements therebetween.
[0025] Terminologies used herein are provided to just mention
specific exemplary embodiments and are not intended to limit the
present invention. Singular expressions used herein include plurals
unless they have definitely opposite meanings. The meaning of
"including" used in this specification gives shape to specific
characteristics, regions, integrals, steps, operations, elements,
and/or component, and do not exclude existence or addition of other
specific characteristics, regions, integrals, steps, operations,
elements, components, and/or groups.
[0026] Spatially relative terms, such as "below" and "above" and
the like, may be used herein for ease of description to describe
one element or feature's relationship to another element(s) or
feature(s) as illustrated in the figures. It will be understood
that spatially relative terms are intended to encompass different
orientations of the device in use or operation in addition to the
orientation depicted in the drawings. For example, if the device in
the figures is turned over, elements described as "below" other
elements or features would then be oriented "above" the other
elements or features. Thus, the exemplary term "below" can
encompass both an orientation of above and below. Apparatuses may
be otherwise rotated 90 degrees or at other angles, and the
spatially relative descriptors used herein are then interpreted
accordingly.
[0027] If not defined differently, all the terminologies including
technical terms and scientific terms used herein have the same
meanings as those skilled in the art generally understand. Terms
defined in common dictionaries are construed to have meanings
corresponding to related technical documents and the present
description, and they are not construed as ideal or overly official
meanings, if not defined.
[0028] The present invention will be described more fully
hereinafter with reference to the accompanying drawings, in which
exemplary embodiments of the invention are shown. As those skilled
in the art would realize, the described embodiments may be modified
in various different ways, all without departing from the spirit or
scope of the present invention.
[0029] FIG. 1 is a schematic flowchart showing a method for
preparing a coating material for thermal spray coating and a method
for coating with a coating material for thermal spray coating
according to an embodiment of the present invention. The flowchart
shown in FIG. 1 is provided to merely exemplify the present
invention, but the preset invention is not limited thereto.
Therefore, the flowchart shown in FIG. 1 may be changed into other
forms.
[0030] As shown in FIG. 1, the method for preparing a coating
material for thermal spray coating includes: mixing a MgO powder
and a Y.sub.2O.sub.3 powder to prepare a composite powder having a
composition of Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to
0.99) (S10); and spraying and drying the composite powder to
prepare a synthesized coating material for thermal spray coating
(S20). The method for coating a coating material for thermal spray
coating may further include other steps.
[0031] The method for coating with a coating material for thermal
spray coating further includes, in addition to the foregoing steps:
injecting the coating material for thermal spray coating toward a
plasma jet, followed by heating (S30); and depositing the coating
material for thermal spray coating in a completely molten or
semi-solid state on a surface of a base metal to form a coating
film (S40). The method for coating with a coating material for
thermal spray coating may further include other steps. Hereinafter,
the foregoing steps will be described in more detail.
[0032] First, in the step S10, a MgO powder and a Y.sub.2O.sub.3
powder are mixed to prepare a composite powder having a composition
of Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to 0.99). A
Mg--Y--O based material has excellent plasma corrosion resistance
when compared with Al.sub.2O.sub.3 and Y.sub.2O.sub.3 crystalline
coating and Al--Y--O-based amorphous coating. In an embodiment of
the present invention, the coating material for thermal spray
coating is prepared by combining Mg and Y, which are verified to
have no side effects when used in a semiconductor manufacturing
process and generate no large crude reaction products when reacting
with a reactive gas such as a Cl or F species.
[0033] As for the composite powder having a composition of
Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to 0.99), in the case
where the value of x is too small, the amount of Y added is slight,
causing a deterioration in the corrosion resistance of the
composite powder. Further, when the value of x is too large, the
amount of Y added is excessive, causing an increase in the
preparation cost of the composite powder. Therefore, the value of x
is controlled to the foregoing range. Preferably, x may be 0.1 to
0.5. Meanwhile, the value of x may be somewhat changed since the
ceramic powder used is partially out of the compositional formulas
of MgO and Y.sub.2O.sub.3 as a chemically stable phase, or the
composite powder is decomposed by high heat while passing through
an ultrahigh-temperature plasma jet, and thus oxygen and the like
vaporizes. When a coating is formed inside vacuum plasma equipment
from a composite powder in which the value of x is controlled to
the foregoing range, chlorides of Mg and Y, which are formed by a
reaction of the coating with a reactive gas such as a Cl or F
species, may easily volatilize, or ultrafine reaction products
generated at the initial stage may be easily detached from a
surface thereof and discharged out of a chamber. Therefore, the
value of x is controlled to the foregoing range so that the
reaction products are not generated, thereby removing bad
influences on the process equipment and goods manufactured
therefrom.
[0034] Here, the diameter of the MgO powder may be 0.1 to 30 .mu.m.
A MgO powder having too small a diameter may be partially lost in a
subsequent spraying process. Alternatively, a MgO powder having too
large a diameter may be somewhat unsuitable for thermal spray
coating. Therefore, the diameter of the MgO powder is controlled to
the foregoing range. Meanwhile, the diameter of the Y.sub.2O.sub.3
powder may be 0.1 to 30 .mu.m. A Y.sub.2O.sub.3 powder having too
small a diameter may be partially lost in a subsequent spraying
process. Alternatively, a Y.sub.2O.sub.3 powder having too large a
diameter may be somewhat unsuitable for thermal spray coating.
Therefore, the diameter of the Y.sub.2O.sub.3 powder is controlled
to the foregoing range.
[0035] When the MgO powder and the Y.sub.2O.sub.3 powder are mixed,
static electricity that induces the powders to have static electric
charges with different polarities may be applied. That is, when the
MgO powder and the Y.sub.2O.sub.3 powder are simply mechanically
mixed, the powders may not be homogeneously mixed. However, since
two particles have static electric charges with different
polarities in a solvent of for example pH 6, hybrid powders can be
homogeneously mixed.
[0036] In the step S20, the composite powder is sprayed and dried
to prepare a synthesized coating material for thermal spray
coating. That is, a coating material for thermal spray coating is
prepared by spraying and drying a composite powder having a
composition of Mg.sub.1-xY.sub.2xO.sub.2x+1 (where x is 0.01 to
0.99). At the time of spraying or drying, a single powder is used
or powders of at least two kinds are mixed at a particular mixing
ratio. In addition, the powder is mixed with a solvent, a binder, a
dispersant, and the like to prepare a mixture. Here, a mixed liquid
of water, acetone, and isopropyl alcohol may be used as the
solvent; a polymer (PVB76), benzyl butyl phthalate, or the like may
be used as the binder; and a polymer may be used as the dispersant.
As necessary, the binder and the dispersant may not be added.
[0037] After the mixture is prepared, a powder having a diameter of
1 to 200 .mu.m is prepared by spraying the mixture in a gas, such
as air, at 70 to 80.degree. C., or spraying the mixture onto fine
grooves formed in a disc rotating at a high rate. Here, when the
diameter of the powder is too small, the powder may be partially
lost at the time of subsequent thermal spray coating.
Alternatively, when the diameter of the powder is too large,
subsequent thermal spray coating may not be done well. Therefore,
the diameter of the powder is controlled to the foregoing
range.
[0038] Meanwhile, since the coating material for thermal spray
coating synthesized by spraying and drying has low hardness, the
coating material for thermal spray coating may be subjected to a
thermal treatment at 900 to 1500.degree. C. When the thermal
treatment temperature for the coating material for thermal spray
coating is too low, the hardness of the coating material for
thermal spray coating is low. Alternatively, when the thermal
treatment temperature for the coating material for thermal spray
coating is too high, the coating material for thermal spray coating
may deteriorate. Therefore, the thermal treatment temperature of
the coating material for thermal spray coating is controlled to the
foregoing range.
[0039] In the step S30, the coating material for thermal spray
coating is injected toward a plasma jet, followed by heating. In
this case, the injected coating material for thermal spray coating
is heated by the plasma jet and is thus volatilized, and is then
deposited on a surface of the base metal. The deposited powder is
rapidly cooled to form a coating film. Here, the base metal may be
a chamber of the vacuum plasma equipment or a part inside the
chamber. Therefore, the coating film is formed on the chamber of
the vacuum plasma equipment, thereby improving the corrosion
resistance to plasma. Since the heating by the plasma jet can be
easily understood by those skilled in the art, detailed
descriptions thereof are omitted.
[0040] Finally, in the step S40, the coating material for thermal
spray coating in a completely molten or semi-solid state is
deposited on a surface of the base metal to form a coating film.
Separately, a raw material powder may be homogeneously dispersed to
improve characteristics of the coating, or a post-treatment may be
performed to enhance the hardness of the sprayed and dried
composite powder. Since the detailed preparation method besides the
foregoing descriptions can be easily understood by those skilled in
the art, detailed descriptions thereof are omitted.
[0041] Meanwhile, the Mg--Y--O coating film formed according to an
embodiment of the present invention may be placed inside the vacuum
plasma equipment. In general, when the plasma atmosphere is formed
in the vacuum plasma equipment, atoms and molecules in the plasma
are excited, dissociated, or ionized to generate etchant species.
In this case, neutral particles are adsorbed on a surface of an
inner wall of the vacuum plasma equipment, and the ions may collide
therewith. As a result, the reaction products may be formed on and
desorbed from the coating film on the surface of the inner wall due
to the dissociation by the ions. Therefore, the reaction products
may contaminate the vacuum plasma equipment and even an object
inside the vacuum plasma equipment. Table 1 below shows the
foregoing materials to be etched, reactive gases, and reaction
products generated therefrom.
TABLE-US-00001 TABLE 1 Material to be etched (substrate, inner
wall, Reaction gas NO parts, etc.) (etchant gas) Reaction product 1
Si, SiO.sub.2, SiN.sub.4 CF.sub.4, SF.sub.6, CHF.sub.3, NF.sub.3
SiF.sub.4 2 Si CF.sub.4, CCl.sub.2F.sub.2, F.sub.113, SiCl.sub.2,
SiF.sub.4, SiCl.sub.4 F.sub.115 3 Al BCl.sub.3, CCl.sub.4, Cl.sub.2
AlCl.sub.4, AlCl.sub.3 4 photoresist O.sub.2, O.sub.2 + CF.sub.4
CO, CO.sub.2, H.sub.2O, HF 5 refractory metal and CF.sub.4,
CCl.sub.2F.sub.2 WF.sub.4 silicon compound thereof W: WSi.sub.2 Ta:
TaSi.sub.2 Mo: MoSi.sub.2
[0042] Meanwhile, when the Mg--Y--O coating film according to an
embodiment of the present invention is used on the inner wall of
the vacuum plasma equipment, the foregoing reaction products may
not be generated. That is, the inner wall of the vacuum plasma
equipment needs to have corrosion resistance, and even though the
reaction products are generated, lump types of products should not
be generated due to high volatility thereof. The Mg--Y--O coating
film according to an embodiment of the present invention has
corrosion resistance to a reactive gas such as a Cl or F species,
and also does not generate lump types of reaction products.
Therefore, a coating film that has completely new characteristics
while not generating reaction products causing failures of goods at
the time of processing can be formed.
[0043] Hereinafter, the present invention will be described in
detail through experimental examples. These experimental examples
are given to merely exemplify the present invention, but the preset
invention is not limited thereto.
EXPERIMENTAL EXAMPLES
[0044] A MgO fine powder and a Y.sub.2O.sub.3 fine powder were
sprayed and dried depending on the mixing ratio thereof, to prepare
a Mg--Y--O based coating material for thermal spray coating. At the
time of spraying and drying, the forming and drying of droplets are
simultaneously performed to prepare a spherical powder. For
atomization, a co-current type of chamber that supplies
high-temperature air was used, and the temperature at an inlet and
the temperature at an outlet, which are basic process parameters,
were set to 108.degree. C. and 120.degree. C., respectively.
Delivery rate of a slurry in which the micro-sized ceramic powder,
binder, and dispersant were mixed was controlled to be 25
liters/hour. In addition, the powder was sprayed and dried while
the rotation rate of a disc was set to 15,000 rpm, thereby
preparing the coating material for thermal spray coating.
[0045] Meanwhile, the coating material for thermal spray coating
was coated using an SG-100 plasma gun manufactured by Praxair, USA.
In this case, power was supplied to the plasma gun using a "PT-800"
power application system manufactured by Plasma Tech, Switzerland.
In addition, for plasma formation, argon gas and hydrogen gas were
used, and the amounts of the gases were controlled to be 36 L/min
and 20 to 40 L/min, respectively. Meanwhile, the current and
voltage were controlled to 850 A and 45 V, respectively, and thus
the applied power was controlled to 30 to 38 kW, and the injection
rate of the coating power was controlled to about 15 g/min. The
distance between the plasma gun and the material to be coated was
controlled to about 120 mm.
Experimental Example 1
[0046] A MgO fine powder and a Y.sub.2O.sub.3 fine powder were
mixed at a weight ratio of 10:90 to prepare an Mg--Y--O based
coating material for thermal spray coating. The remaining
experimental procedure was the same as that of the foregoing
experimental example.
Experimental Example 2
[0047] A MgO fine powder and a Y.sub.2O.sub.3 fine powder were
mixed at a weight ratio of 30:70 to prepare an Mg--Y--O based
coating material for thermal spray coating. The remaining
experimental procedure was the same as that of the foregoing
experimental example.
Experimental Example 3
[0048] A MgO fine powder and a Y.sub.2O.sub.3 fine powder were
mixed at a weight ratio of 50:50 to prepare an Mg--Y--O based
coating material for thermal spray coating. The remaining
experimental procedure was the same as that of the foregoing
experimental example.
Experimental Example 4
[0049] A MgO fine powder and a Y.sub.2O.sub.3 fine powder were
mixed at a weight ratio of 70:30 to prepare an Mg--Y--O based
coating material for thermal spray coating. The remaining
experimental procedure was the same as that of the foregoing
experimental example.
Experimental Example 5
[0050] A MgO fine powder and a Y.sub.2O.sub.3 fine powder were
mixed at a weight ratio of 90:10 to prepare an Mg--Y--O based
coating material for thermal spray coating. The remaining
experimental procedure was the same as that of the foregoing
experimental example.
Comparative Example 1
[0051] For forming an amorphous based coating, an Al.sub.2O.sub.3
fine powder and a Y.sub.2O.sub.3 fine powder were mixed at a weight
ratio of 50:50 to prepare an Al--Y--O based coating material for
thermal spray coating. The remaining experimental procedure was the
same as that of the foregoing experimental example.
Comparative Example 2
[0052] A MgO fine powder and a ZrO.sub.2 fine powder were mixed at
a weight ratio of 10:90 to prepare an Mg--Zr--O based coating
material for thermal spray coating. The remaining experimental
procedure was the same as that of the foregoing comparative
example.
Comparative Example 3
[0053] A MgO fine powder and a ZrO.sub.2 fine powder were mixed at
a weight ratio of 30:70 to prepare an Mg--Zr--O based coating
material for thermal spray coating. The remaining experimental
procedure was the same as that of the foregoing experimental
example.
Comparative Example 4
[0054] A MgO fine powder and a ZrO.sub.2 fine powder were mixed at
a weight ratio of 50:50 to prepare an Mg--Zr--O based coating
material for thermal spray coating. The remaining experimental
procedure was the same as that of the foregoing experimental
example.
Comparative Example 5
[0055] A MgO fine powder and a ZrO.sub.2 fine powder were mixed at
a weight ratio of 70:30 to prepare an Mg--Zr--O based coating
material for thermal spray coating. The remaining experimental
procedure was the same as that of the foregoing experimental
example.
Comparative Example 6
[0056] A MgO fine powder and a ZrO.sub.2 fine powder were mixed at
a weight ratio of 90:10 to prepare an Mg--Zr--O based coating
material for thermal spray coating. The remaining experimental
procedure was the same as that of the foregoing experimental
example.
[0057] Observation of Structure of Coating Material for Thermal
Spray Coating
[0058] Experimental Results of Experimental Example 1
[0059] FIG. 2 shows scanning electron microscopic images
illustrating Mg--Y--O based materials for thermal spray coating
prepared according to Experimental Examples 1 to 5 of the present
invention. As shown in FIG. 2, it could be confirmed that the MgO
finer powder and the Y.sub.2O.sub.3 fine powder were homogeneously
mixed to prepare a Mg--Y--O based coating material for thermal
spray coating.
[0060] X-Ray Diffraction Analysis of Coating Material for Thermal
Spray Coating
[0061] Experimental Results of Experimental Examples 1 to 5
[0062] FIG. 3 shows X-ray diffraction graphs illustrating Mg--Y--O
based materials for thermal spray coating prepared according to
Experimental Examples 1 to 5 of the present invention. That is,
FIG. 3 shows X-ray diffraction analysis results of Mg--Y--O based
coating materials for thermal spray coating prepared by spraying
and drying the MgO fine powder and the Y.sub.2O.sub.3 fine powder
of different mixing ratios according to Experimental Examples 1 to
5.
[0063] As shown in FIG. 3, crystalline peaks corresponding to cubic
MgO and cubic Y.sub.2O.sub.3 were observed at all the mixing ratios
of MgO:Y.sub.2O.sub.3 for the Mg--Y--O based coating materials for
thermal spray coating. Therefore, it could be confirmed that MgO
and Y.sub.2O.sub.3 were incorporated into the coating material for
thermal spray coating.
[0064] Analysis Results of Structure of Coating Material for
Thermal Spray Coating
[0065] A coating for thermal spray coating according to Comparative
Example 1 was formed in known optimum thermal spray coating
conditions. In addition, coatings for thermal spray coating
according to Comparative Examples 2 to 6 and Experimental Examples
1 to 5 were formed in the same thermal spray coating
conditions.
[0066] FIG. 4 shows scanning electron microscopic images obtained
by observing polished surfaces of Mg--Y--O-based coatings formed by
a thermal spray coating process according to Experimental Examples
1 to 4 of the present invention. As shown in FIG. 4, normal
coatings were formed in Experimental Examples 1 to 4. As for the
coatings formed according to Experimental Examples 1 to 4, white,
gray, and black areas were shown to be mixed, and the higher the
proportion of MgO in a mixing ratio of MgO and Y.sub.2O.sub.3, the
larger the black area.
[0067] The coating for thermal spray coating according to
Experimental Example 5 was not deposited and thus not formed on the
surface of the base metal. In Experimental Example 5, the coating
was not completely molten and thus was very vulnerable, and normal
coating was impossible due to large crude pores and inside cracks.
Meanwhile, the coatings formed according to Comparative Examples 2
to 6 showed similar tends to the coatings formed according to
Experimental Examples 1 to 4, and thus illustrations thereof will
be omitted.
[0068] EDX Analysis Results of Coating Material for Thermal Spray
Coating
[0069] The white, gray, and black areas shown in the coatings in
FIG. 4 were analyzed in more detail using EDX. That is, in order to
check the difference in shading among the white, gray, and black
areas, composition analysis thereof was conducted using EDX.
[0070] FIG. 5 shows graphs obtained by analyzing a coating formed
according to Experimental Example 1 of the present invention using
an EDX system.
[0071] As shown in FIG. 5, Mg, Y, and O elements corresponding to
MgO particles and Y.sub.2O.sub.3 particles are mixed in the coating
of Experimental Example 1. Particularly, since the amount of Y was
relatively greater than the amount of Mg in the white area, it
could be confirmed that the white area was composed of more
Y.sub.2O.sub.3 particles than MgO particles. Meanwhile, since the
amount of Mg was more increased than the amount of Y toward the
black area, it could be confirmed that the black area was composed
of more MgO particles than Y.sub.2O.sub.3 particles.
[0072] X-Ray Diffraction Experiment on Coatings Formed Through
Thermal Spray Coating and Experimental Results
[0073] FIG. 6 shows X-ray diffraction graphs illustrating coatings
formed according to Experimental Examples 1 to 4 of the present
invention.
[0074] In Experimental Examples 2 to 4, crystalline peaks
corresponding to cubic MgO and cubic Y.sub.2O.sub.3 were observed
even after thermal spray coating. However, it could be confirmed
that an amorphous peak was shown in Experimental Example 1. This
was the same as a crystallized structure of a general amorphous
coating.
[0075] Corrosion Resistance Test on Coatings Formed Through Thermal
Spray Coating and Test Results
[0076] A corrosion resistance test on coatings was conducted under
the plasma atmosphere containing a corrosive gas of a Cl species.
That is, the corrosion resistance of the coating was measured for
900 seconds under conditions of plasma power of 800 W, bias power
of 300 W, 100 seem of BCl.sub.3, 100 seem of Cl.sub.2, and pressure
of 20 mTorr.
[0077] FIG. 7 shows scanning electron microscopic images of etched
surfaces before and after a corrosion resistance test of coatings
formed according to Experimental Examples 1 to 4. That is, upper
panels of FIG. 7 show scanning electron microscopic images before
the corrosion resistance test of the coatings, and lower panels of
FIG. 7 show scanning electron microscopic images after the
corrosion resistance test of the coatings.
[0078] As shown in FIG. 7, the coatings of Experimental Examples 1
to 3 were shown to have almost the same coating surfaces that were
hardly etched. However, the coating of Experimental Example 4 was
shown to have a coating surface that was remarkably etched along
large crude pores as well as interfaces of droplets.
[0079] Etching Rate Test on Coatings Formed Through Thermal Spray
Coating and Test Results
[0080] The etching rates of the coatings were measured under the
plasma atmosphere containing a corrosive gas of a Cl species. The
plasma etching rate was calculated by measuring the step difference
between a region etched with plasma containing a reactive gas of a
Cl species and a region not etched with the plasma while the
surface of the coating was masked, and then dividing the step
difference by the etching time.
[0081] FIG. 8 is a graph illustrating etching rates in coatings
formed according to Experimental Examples 1 to 4 and Comparative
Examples 1 to 4 of the present invention.
[0082] As shown in FIG. 8, the etching rates of the coatings in
Experimental Examples 1 to 3 were significantly improved when
compared to the etching rates of the coatings in Comparative
Examples 1 to 5. In particular, the etching rate of the coating in
Experimental Example 1 was about 11 nm/min, which was the lowest
value. That is, the etching rate in Experimental Example 1 was
improved so as to be merely about 27% of 40 nm/min, which is an
approximate etching rate of the coatings in Comparative Examples 1
to 5. More specifically, as a result of etching the coatings in
Comparative Examples 2 to 5 under the plasma atmosphere containing
a gas of a Cl species, the coatings showed significantly high
etching rates, which were higher compared with the coating in
Comparative Example 1.
[0083] Experiment on Formation of Ultrafine Reaction Products of
Coatings Formed Through Thermal Spray Coating and Experimental
Results
[0084] The experiment on the formation of ultrafine reaction
products of the coatings was conducted under the plasma atmosphere
containing a corrosive gas of a Cl species. That is, the experiment
on the formation of ultrafine reaction products of the coatings was
conducted for 900 seconds under conditions of plasma power of 800
W, 100 seem of BCl.sub.3, 100 seem of Cl.sub.2, and pressure of 20
mTorr.
[0085] FIG. 9 shows scanning electron microscopic images
illustrating exposed surfaces of coatings formed according to
Experimental Examples 1 to 4 of the present invention. Here, upper
panels of FIG. 9 show scanning electron microscopic images before
the experiment on the formation of ultrafine reaction products of
the coatings, and lower panels of FIG. 9 show scanning electron
microscopic images after the experiment on the formation of
ultrafine reaction products of the coatings.
[0086] As shown in FIG. 9, the coatings in Experimental Examples 1
to 4 of the present invention, which were exposed to the plasma
atmosphere containing a corrosive gas of a Cl species, showed
smooth surfaces without ultrafine reaction products. That is, the
formation of the ultrafine reaction products were remarkably
suppressed and thus minimized in the coatings in Experimental
Examples 1 to 4 compared to the coatings in Comparative Examples 1
to 5.
[0087] In the conventional art, a multi-component based ceramic
material having three or more elements was thermal spray coated, so
that the coating film was mostly formed in an amorphous phase. For
example, the Al.sub.2O.sub.3 fine powder and the Y.sub.2O.sub.3
powder were mixed to prepare a composite powder having a size of 40
to 60 .mu.m, and then the composite powder was thermal spray
coated, thereby forming a coating in an amorphous phase. Through
this method, Al--Y--O coatings, Al--Zr--O coatings, and Y--Zr--O
coatings, which had greatly improved corrosion resistance to plasma
compared with coatings composed of Y.sub.2O.sub.3, were formed.
However, although the Al--Y--O coatings and the Al--Zr--O coatings
showed excellent corrosion resistance under the reactive gas
atmosphere containing a reactive gas, such as a Cl or F species,
the corrosion resistance was largely changed due to the thermal
spray coating, and thus it was not easy to secure reproducibility.
Moreover, since the surface of the coating reacted with a reactive
gas such as a Cl or F species, a large amount of ultrafine reaction
products were generated. Meanwhile, the Y--Zr--O coatings were
proposed to overcome the limitations of the foregoing amorphous
coatings, but showed problems, like the Al--Zr--O based coatings,
in that they have low chemical corrosion resistance to a reactive
gas such as a Cl or F species under the plasma atmosphere
containing the reactive gas such as the Cl or F species. Moreover,
the Y--Zr--O coatings had a problem in which the etching of
surfaces of the Y--Zr--O coatings caused ultrafine reaction
products, similarly to the Al--Zr--O based coatings.
[0088] FIG. 10 is an image showing a state in which a large crude
reaction product generated during a manufacturing procedure is
dropped on a circuit.
[0089] As shown in FIG. 10, the use of the foregoing Al--Y--O
coating, Al--Zr--O coating, Y--Zr--O coating, and Y--Zr--O coating
caused the formation of large crude reaction products, which
contaminated processing equipment and goods manufactured in the
processing equipment. In contrast, the coatings formed according to
experimental examples of the present invention had very high
physical corrosion resistance under the plasma atmosphere
containing a corrosive gas of a Cl species when compared with the
conventional coatings formed according to the comparative examples.
That is, in the case where the coatings formed according to
experimental examples of the present invention are used, the
lifespan of the parts of the semiconductor equipment can be
extended to significantly improve the process efficiency, and the
failure rate of goods due to contamination caused by the reaction
products can be minimized.
[0090] The physical corrosion resistance and chemical corrosion
resistance of the coatings formed according to the experimental
examples of the present invention were improved by about 500% or
higher when compared with the coatings formed according to the
comparative examples. Therefore, the Mg--Y--O alloy can be used as
a protective coating agent useful for equipment and internal parts
thereof, which are used under the corrosive atmosphere in a poor
state.
[0091] While the present invention has been described above with
respect to certain preferred embodiments thereof, it will be
understood by those skilled in the art that various changes and
modifications may be made without departing from the spirit and
scope of the spirit and scope of the appended claims.
* * * * *