U.S. patent application number 09/962918 was filed with the patent office on 2002-06-27 for silica glass jig for semiconductor industry and method for producing the same.
Invention is credited to Inaki, Kyoichi, Maruko, Yoichiro, Sato, Tatsuhiro, Segawa, Tohru.
Application Number | 20020078886 09/962918 |
Document ID | / |
Family ID | 26600969 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020078886 |
Kind Code |
A1 |
Segawa, Tohru ; et
al. |
June 27, 2002 |
Silica glass jig for semiconductor industry and method for
producing the same
Abstract
A silica glass jig for semiconductor industry, which is does not
contaminate semiconductor elements, and generates less cracks and a
production method thereof are provided. A silica glass jig for
semiconductor industry, characterized by having, on the surface of
the jig, pyramidal projected structures with their cut-off apices
and concave portions provided therebetween, and small projections
are uniformly distributed thereon; the silica glass jig has a
surface with many dimple-form concave portions each having a width
of from 20 to 300 .mu.m exist and there are grooves each having a
width of from 0.5 to 50 .mu.m at an interval of from 20 to 300
.mu.m, and small projections each having a width of from 1 to 50
.mu.m and having a height of from 0.1 to 10 .mu.m are uniformly
distributed between the grooves and in the grooves. A method for
producing such is machining the surface of the silica glass jig to
form irregularities, and then treating the resulting surface with a
treating solution containing hydrogen fluoride and ammonium
fluoride; or immersing the silica glass jig in a first processing
solution containing hydrogen fluoride, ammonium fluoride, and an
organic acid, and then immersing it at least once in a second
processing solution, wherein the content of the organic acid is
higher than that of the first processing solution.
Inventors: |
Segawa, Tohru;
(Koriyama-shi, JP) ; Sato, Tatsuhiro; (Vancouver,
WA) ; Maruko, Yoichiro; (Sasebo-shi, JP) ;
Inaki, Kyoichi; (Tokorozawa-shi, JP) |
Correspondence
Address: |
LAW OFFICE OF ANDREW L. TIAJOLOFF
C/O ROBIN BLECKER & DALEY
330 MADISON AVENUE
NEW YORK
NY
10017
US
|
Family ID: |
26600969 |
Appl. No.: |
09/962918 |
Filed: |
September 25, 2001 |
Current U.S.
Class: |
118/500 ;
216/109; 216/97 |
Current CPC
Class: |
C03C 15/00 20130101;
C03C 19/00 20130101; C23C 16/4581 20130101 |
Class at
Publication: |
118/500 ; 216/97;
216/109 |
International
Class: |
C23F 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2000 |
JP |
JP 2000-296733 |
Sep 28, 2000 |
JP |
JP 2000-296756 |
Claims
1. A silica glass jig for semiconductor industry, characterized by
having on the surface of the above-described jig, pyramidal
projected structures with their cut-off apices and concave portions
therebetween, and small projections are uniformly distributed
thereon.
2. A silica glass jig for semiconductor industry described in claim
1, characterized in that, on the surface thereof, the concave
portions are dimpled and each having a width of from 20 to 300
.mu.m, and there are grooves each having a width of from 0.5 to 50
.mu.m at an interval of from 20 to 300 .mu.m, and between the
grooves and in the grooves, small projections each having a width
of from 1 to 50 .mu.m and a height of from 0.1 to 10 .mu.m are
uniformly distributed.
3. A silica glass jig for semiconductor industry described in claim
1 or 2, wherein the maximum width of the bottom portions of the
pyramidal projected structures with their cut-off apices is from 70
to 1000 .mu.m and a height from the bottom portions to the top
portions of the projected structures is from 10 to 100 .mu.m, and
the maximum width of the bottom portions of the small projections
uniformly distributed on the protruded structures is from 1 to 50
.mu.m and the height thereof from the bottom portions to the top
portions is from 0.1 to 10 .mu.m.
4. A silica glass jig for semiconductor industry described in one
of the preceeeding claim 1 to 3, wherein the average roughness Ra
of the silica glass jig for semiconductor industry is in a range of
from 1 to 10 .mu.m.
5. A method for producing a silica glass jig for semiconductor
industry, characterized by machining the surface of the silica
glass jig to form irregularities, and then treating the resulting
surface with a treating solution containing hydrogen fluoride and
ammonium fluoride.
6. A method for producing a silica glass jig for semiconductor
industry described in claim 5, wherein the treating solution
further contains an organic carboxylic acid.
7. A method for producing a silica glass jig for semiconductor
industry described in claim 6, wherein the organic carboxylic acid
is acetic acid
8. A method for producing a silica glass jig for semiconductor
industry described in claim 5, wherein the machining is a
sandblasting treatment.
9. A method for producing a silica glass jig for semiconductor
industry described in preceeding claims 5 to 7, wherein the
treating solution contains from 10 to 30% by mass of hydrogen
fluoride, from 5 to 30% by mass of ammonium fluoride, from 45 to
70% by mass of an organic carboxylic acid, and rest being
water.
10. A method for producing a silica glass jig for semiconductor
industry by immersing the silica glass jig in a first processing
solution containing hydrogen fluoride, ammonium fluoride, and an
organic acid, and then immersing it at least once in a second
processing solution, wherein the content of the organic acid is
higher than that of the first processing solution.
11. A method for producing a silica glass jig for semiconductor
industry, described in claim 10, wherein the first processing
solution is an aqueous solution containing from 15 to 50% by mass
of hydrogen fluoride, from 6 to 30% by mass of ammonium fluoride,
and from 30 to 50% by mass of an organic acid, and the second
processing solution is a processing solution containing from 5 to
20% by mass of hydrogen fluoride, from 6 to 30% by mass of ammonium
fluoride, and from 40 to 70% by mass of the organic acid.
12. A method for producing a silica glass jig for semiconductor
industry described in claim 11, wherein the organic acid is acetic
acid
Description
INDUSTRIAL FIELD OF APPLICATION
[0001] The present invention relates to a silica glass jig for
semiconductor industry, particularly to a silica glass jig for
semiconductor industry, wherein small projections are uniformly
distributed on the surface thereof, and also to a production method
thereof.
PRIOR ART
[0002] Hitherto, in the production of semiconductor elements, it
has been carried out to form a coat made of coating material such
as silicon oxide, silicon nitride or polysilicon, etc., on a
substrate and in this case, the coating material deposits not only
on the substrate but also on the surfaces of the inside of a
reaction chamber for carrying out coating and on the surface of
members disposed in the reaction chamber (hereinafter, the reaction
chamber and the members are referred to as simply jigs). When the
jig is made of a silica glass and when the thickness of the coated
material becomes thicker than a definite thickness, by the
difference in the thermal expansion coefficients between the jig
and the coated material, a stress is generated to cause peeling off
or form particles, which cause to contaminate the semiconductor
elements. Particularly, in the case of forming the coat by a CVD
process of a high temperature, the tendency of causing peeling off
is more increased. Accordingly, it is general to wash the jig after
using for a definite time, but washing takes a long time as well as
increases a step number, which results in increasing the production
cost. In the case of growing a polysilicon film on a semiconductor
element by an LPCVD (Low Pressure Chemical Vapor Deposition)
method, it is effective that the quartz glass jig has formed on the
surface many irregularities. By the irregularities, the generation
of stress by the difference in the thermal expansion coefficients
between a polysilicon film deposited on the surface of the quartz
glass jig and the quartz glass jig is reduced and the occurrence of
releasing of the film and the formation of cracks can be prevented.
For the formation of the above-described irregularities, machining
is used, but by the machining, a layer having microcracks is formed
under the irregularity-formed surface formed in the jig and the
depth of the cracks sometimes reaches 100 .mu.m. When such deep
cracks occur, substances of contaminating a semiconductor element
enter the cracks, and at the heat treatment of the semiconductor
element, it sometimes happens that the substances are volatized to
contaminate the semiconductor element. Accordingly, in the initial
stage of the treatment of semiconductor element, after operating
the process for a while without using semiconductor element, the
treatment is carried out. Also, the above-described cracks become
cracks of initiating the destruction of the jig to lower the
strength of the jig and shorten the usable life of the jig as well
as there are the faults that at washing or cleaning the jig, the
irregularities of the jig are changed, the surface state of the jig
is changed, and a homogeneous vapor-phase reaction cannot be
carried out. For solving the faults, for example, Japanese Patent
Laid-Open No. 59744/1998 proposed that a machined jig is subjected
to an etching treatment with hydrofluoric acid containing from 3 to
20% by mass of hydrogen fluoride to release the microcracks,
whereby the microcrack-free surface is formed. However, in the jig
treated by the method, the irregularities become too large to form
cone-shaped concave portions, the fine irregularities are reduced,
and thus the jig is unsatisfactory as a jig for treating
semiconductor elements.
[0003] Also, a method of forming the irregularities on the surface
of a silica glass jig by a chemical treatment without using
machining is proposed, for example, in Japanese Patent Laid-Open
No. 106225/1999. In the chemical treatment, microcracks are not
formed in a jig, the contamination of semiconductor elements by
contaminants from the insides of cracks does not occur, also, at
washing of the jig, the irregularities on the surface of the jig
are scarcely changed, and a homogeneous chemical reaction can be
carried out. However, in the method, there are problems that when
large irregularities, such as, for example, the roughness Ra of at
least 3 are formed, smooth portions exist at the slanting surfaces
of the convex portions and the bottom portions of the concaves,
polysilicon attaches to the smooth portions, by the difference in
the thermal expansion coefficients between the attached polysilicon
film and the jig, cracks occur in the jig to for particles, which
give bad influences on semiconductor elements and lower the yield
thereof.
PROBLEMS THAT THE INVENTION IS TO SOLVE
[0004] In view of these circumstances, as the results of making
various investigations, the present inventors have found that by
treating a mechanically roughened silica glass jig with a specific
aqueous solution a silica glass jig, wherein microcracks are
released and there is no entering of decontaminates, is obtained
and by uniformly distributing many small projections on the surface
of the jig, a silica glass jig having no occurrence of cracks by
the difference in the thermal expansion coefficients between the
jig and an attached film such as a polysilicon film, etc., is
obtained, and have accomplished the present invention.
[0005] The present inventors further made the investigations based
on the consideration that an excellent quartz glass jig was
obtained by improving the chemical processing method it was found
that by first forming relatively large pyramidal projections with
their cut-off apices by the chemical processing method and further
forming small projections on the above-described projections, a
quartz glass jig, which more reduces the occurrence of peeling off
of film, causes very less formation of cracks by the difference in
the thermal expansion coefficients between the jig and the coated
material, and can reduce the washing times of the jig, is obtained
and have accomplished the present invention.
[0006] An object of the invention is to provide a silica glass jig
for semiconductor industry, which causes less peeling off of coated
film, does not generate impurities contaminating semiconductor
elements at the use thereof, and can reduce the washing times of
jig, as well as causes less formation of cracks and shows a
prolonged usable life.and does not cause cracks.
[0007] Also, another object of the invention is to provide a method
of producing the above-described silica glass jig for semiconductor
industry.
MEANS FOR SOLVING THE PROBLEMS
[0008] The present invention has been made for attaining the
above-described objects, and the invention is a silica glass jig
for semiconductor industry, characterized by having on the surface
of the above-described jig, pyramidal projected structures with
their cut-off apices and concave portions provided therebetween,
and having small projections which are uniformly distributed
thereon and a production method thereof.
[0009] The silica glass jig for semiconductor industry of the
invention is a jig, which is used in a semiconductor industry such
as, for example, a furnace core tube, a boat for placing a wafer,
etc., and on the surface of the jig, there are pyramidal projected
structures with their cut-off apices and also small projections are
further uniformly distributed on the smooth portions between
them.
[0010] For the silica glass jig of the invention a surface with
many small dimpled concave portions each having a width of from 20
to 300 .mu.m is preferred, on which there are grooves each having a
width of from 0.5 to 50 .mu.mat an interval of from 20 to 300
.mu.m, and between the grooves and in the grooves, small
projections each having a width of from 1 to 50 .mu.m and a height
of from 0.1 to 10 .mu.mare uniformly distributed.
[0011] The silica glass jig for semiconductor industry of the
invention is a jig, such as, for example, a furnace core tube, a
boat for placing a wafer, etc., wherein on the surface of the
silica glass jig, many small dimpled concave portions each having a
width of from 20 to 300 .mu.m exist at a part or the whole portions
thereof, there are grooves having a width of from 0.5 to 50 .mu.m
at an interval of from 20 to 300 .mu.m, and small projections
having a width of from 1 to 50 .mu.m and a height of from 0.1 to 10
.mu.m are uniformly distributed between the grooves and in the
grooves. By having the above-described structure, the silica glass
jig for semiconductor industry of the invention forms less
particles and impurities, can keep the high cleanness of the
surface, and can sufficiently shows the high-pure performance as
the bulk of the silica glass. In the silica glass jig of the
invention, even when, for example, a polysilicon film is deposited
on the surface thereof, the stress based on the different in the
thermal expansion coefficients is moderated by the above-described
small projections, cracks are hard to occur in the jig, and the
life of the jig is prolonged. The above-described grooves are the
portions formed by releasing deep microcracks occurred in the case
of machining, the width thereof is preferably in the range of from
0.5 to 50 .mu.m. When the width of the grooves is shorter than 0.5
.mu.m, the extension of the microcracks is insufficient and the
residue of impurities remains, while when the width of the grooves
exceeds 50 .mu.m, the etching off amount of the surface is large,
whereby the dimensional precision is out of order. Also, the
interval of the grooves changes according to the machining means
but is preferably in the range of from 20 to 300 .mu.m.
Furthermore, between the grooves, there are small dimpled concave
portions and the width thereof is in the range of from 20 to 300
.mu.m. Also, between these groups and in the grooves, small
projections are uniformly distributed. The sizes of the small
protections differ according to the kind of the treating solution
used but it is better that the width is in the range of from 1 to
50 .mu.m and the height is in the range of 0.1 to 10 .mu.m. When
the sizes of the small projections are less than the
above-described ranges, the moderation of the heat stress of the
accumulated film is insufficient and cracks sometimes occur, while
when the sizes exceed the above-described range, smooth portions
remain.
[0012] It is preferred that in the above-described projected
structures, the maximum width of the bottom portions thereof is
from 70 to 1000 .mu.m, and the height from the bottom portions to
the top portions is in the range of from 10 to 100 .mu.m. When the
maximum width of the bottom portions of the projected structures is
shorter than 70 .mu.m, the surface roughness is small and thus the
effect at the formation of a thick-coated film is insufficient,
while the formation of the structures, in which the maximum width
of the bottom portions exceeds 1000 .mu.m, is technically
difficult. Also, the height of the projected structures is lower
than 10 .mu.m, the irregularities are shallow and thus the peeling
off preventing effect is insufficient, while the formation of the
protected structures, in which the height exceeds 100 .mu.m, is
difficult.
[0013] It is better that in the small projections formed on the
projected structures and the sides thereof, and on the flat
portions of the concave portions between the projected structures,
the maximum width of the bottom portions thereof is 50 .mu.m or
shorter and the height from the bottom portions to the top portions
is lower than 10 .mu.m. When the maximum width of the small
projections exceeds 50 .mu.m, flat portions remain and cracks and
particles are liable to form. Because the silica glass jig for
semiconductor industry of the invention has the above-described
surface structure, the formation of cracks by the difference in the
thermal expansion coefficients between the jig and the deposited
film can be reduced, the occurrence of peeling off of the film
deposited on the jig is less, and the washing times of the jig
having attached thereto a thick film can be reduced.
[0014] It is another object of the invention to provide a method
for producing a silica glass jig for semiconductor industry by
machining the surface of the silica glass jig to form
irregularities, and then treating the resulting surface with a
treating solution containing hydrogen fluoride and ammonium
fluoride. Particularly, a treating solution containing from 10 to
30% by mass of hydrogen fluoride, from 5 to 30% by mass of ammonium
fluoride, and resin being water is preferred and further, the
treating solution may further preferably contain an organic
carboxylic acid in the range of from 45 to 70% by mass. By
containing the organic carboxylic acid, the small projections
having the sizes of the above-described range can be uniformly and
easily formed. As the organic carboxylic acid, there are
water-soluble organic carboxylic acids such as formic acid, acetic
acid, propionic acid, etc. In these organic carboxylic acids,
acetic acid is particularly preferred because of the high
solubility in water and a low cost.
[0015] In the production method of the invention, first, the
surface of a silica glass jig is roughened by machining as
described above, and as the machining method, there are a sand
blast method of blowing silicon dioxide fine particles, carbon fine
particles, or ceramic fine particles, a grinding method using
diamond grindstone particles, and a wet blast method using a
slurry-form free grindstone particles. In these methods, the sand
blast method is preferred. By the sand blast method, a glass powder
is easily released from the surface of the jig and also there
occurs no penetration of a coolant liquid into microcracks. Then,
after machining, particles attached are removed by washing, the jig
is repeatedly immersed in a treating solution containing from 10 to
30% by mass of hydrogen fluoride and from 5 to 30% by mass of
ammonium fluoride, and rest being water, and preferably further
containing an organic carboxylic acid in the range of from 45 to
70% by mass, whereby the microcracks are released to form many
grooves having a width of from 0.5 to 50 .mu.m and to form small
dimpled concave portions each having a width of from 20 to 300
.mu.m between the grooves, and further to make small projections
having a width of from 1 to 50 .mu.m and a height of from 0.1 to 10
.mu.m uniformly distribute between the grooves and in the grooves.
When the amount of the organic carboxylic acid contained in the
treating solution is less than 45% by mass, the small projections
become large and the uniform distribution thereof becomes
difficult, while when the amount of the organic carboxylic acid
exceeds 70% by mass, the small projections become too small,
whereby the effect thereof is not obtained. Also, when the content
of ammonium fluoride in the processing solution is less than 5% by
mass, etching by hydrogen fluoride only occurs, while when the
content of ammonium fluoride exceeds 30% by mass, only the
irregularities by about 30% by mass of ammonium fluoride are
formed, the cost is increased, and thus the use of the excessive
amount of ammonium fluoride is not suitable for practical use.
[0016] Alternatively, the present invention provides a method for
production of the silica glass jig for semiconductor industry, in
which first, a silica glass jig is immersed in a first treating
solution containing hydrogen fluoride, ammonium fluoride, and an
organic acid, and then the jig is immersed at least once in a
second treating solution having a larger content of the organic
acid than that of the above-described treating solution, whereby
pyramidal projected structures with their cut-off apices and
concave portions provided therebetween are formed on the surface of
the jig and also small projections are uniformly distributed on
them. It is better that the content of hydrogen fluoride in the
first treating solution used is from 15 to 50% by mass, the content
of ammonium fluoride is from 6 to 30% by mass, and the content of
the organic acid is in the range of from 30 to 50% by mass. Also,
it is better that the content of hydrogen fluoride in the second
treating solution is from 5 to 20% by mass, the content of ammonium
fluoride is from 6 to 30% by mass, and the content of the organic
acid is in the range of from 40 to 70% by mass, the range of the
organic acid is selected such that the range is more than the range
thereof in the first treating solution.
[0017] When the content of ammonium fluoride in the above-described
first treating solution is less than 6% by mass, etching by
hydrogen fluoride only occurs and irregularities are not formed,
and when the content of ammonium fluoride exceeds 30% by mass, the
effect of forming irregularities is same, and the cost is
increased, and thus the excessive use of ammonium fluoride is not
suitable for practical use. Also, when the content of the organic
acid is less than 20% by mass, the effect of containing the organic
acid is less, and when the content of the organic acid exceeds 50%
by mass, the projected structures become too small and the effect
at the formation of thick film is insufficient. Furthermore, when
the content of ammonium fluoride in the second treating solution is
less than 6% by mass, etching by hydrogen fluoride only occurs and
irregularities are not formed, and also when the content of the
organic acid is less than 40% by mass, projections become too
large, and the preparation of the treating solution, in which the
content of the organic acid exceeds 70% by mass, is difficult.
[0018] As the organic acid, a water-soluble organic carboxylic acid
is particularly preferred, practically, there are formic acid,
acetic acid, propionic acid, etc., and in these acids, acetic acid,
which has a high solubility in water and is inexpensive, is
suitable.
MODE FOR CARRYING OUT THE INVENTION
[0019] Then, the example of the invention is described but the
invention is not limited to the example.
EXAMPLES
Example 1
[0020] Using silicon carbide abrasives (#320), the inside surface
of a furnace core tube for LPCVD was subjected to a sand blast work
by blowing the abrasives using compressed air. The surface
roughness Ra was 3 .mu.m. When the furnace core tube was immersed
in a treating solution bath of 15% by mass of hydrogen fluoride,
15% by mass of ammonium fluoride and 50% by mass of acetic acid for
one hour and the furnace core tube after the treatment was observed
by a scanning electron microscope, many small projections were
observed as shown in FIG. 1. Also, microcracks were opened and many
grooves having a width of about 1 .mu.m were observed. Using the
furnace core tube, a CVD process of forming a polysilicon film on a
silicon wafer was carried out. The furnace core tube was used until
the polysilicon film of 30 .mu.m thick was attached but the
generation of particles was less and the yield for the silicon
wafer was high. Also, in the polysilicon film-attached furnace core
tube after use, cracks were not generated and the film was not
peeled off.
Example 2
[0021] Alternativly a treating bath can be used containing 30% by
mass of hydrogen fluoride, 10% by mass of ammonium fluoride, and
35% by mass of acetic acid for one hour to obtain the furnace core
tube having pyramidal projected structures with their cut-off
apices having the maximum width of the bottom portions of 300 .mu.m
and a height from the bottom portions to the top portions of 30
.mu.m, and concave portions provided therebetween. As to the
dimensions of the projected structures, the scanning electron
microphotograph of the furnace core tube treated as described above
was taken as shown in FIG. 3, the maximum width of the bottom
portion of each of the projected structures, and the height from
the bottom portion to the top portion of each projected structure
were determined and the dimensions were shown as the mean value.
When the treated furnace core tube was measured by a roughness
meter, the average roughness Ra was 3 .mu.m. The furnace core tube
was further immersed in a treating solution of 15% by mass of
hydrofluoric acid, 15% by mass of ammonium fluoride, and 50% by
mass of acetic acid. When the surface of the furnace core tube
obtained was observed by a scanning electron microscope, small
projections having the maximum width of the bottom portions of 15
.mu.m and the height from the bottom portion to the top portion of
2 .mu.m were uniformly distributed as shown in FIG. 4. The average
roughness Ra of the furnace core tube was 3.5 .mu.m and the whole
body was opaque. Using the furnace core tube, the formation of a
polysilicon film on a silicon wafer was carried out by CVD process.
The furnace core tube was used until the polysilicon film of 30
.mu.m thick was attached to the furnace core tube, particles were
not generated and the silicon wafer was treated with a high yield.
Also, in the polysilicon film-attached furnace core tube after use,
cracks were not generated and the film was not peeled off.
Comparative Example 1
[0022] Using a furnace core tube subjected to the sand blast work
as in Example 1, the CVD process of forming a polysilicon film on a
silicon wafer was carried out as in Example 1. After the initiation
of the CVD treatment, many particles were generated, whereby the
treatment of the wafer could not carried out for a while.
Thereafter, the furnace core tube was used until the polysilicon
film of 30 .mu.m thick was attached, some cracks generated but the
film was not peeled off.
Comparative Example 2
[0023] The furnace core tube subjected to the sand blast work in
Example 1 was subjected to an etching treatment with 20% by mass of
hydrogen fluoride for one hour. The surface roughness Ra of the jig
obtained was 7 .mu.m. When the surface thereof was observed by a
scanning electron microscope, many smooth dimple-form (mortar-form)
concave portions were observed as shown in FIG. 2. Using the
furnace core tube, the CVD treatment as in Example 1 was carried
out. After attaching a polysilicon film of 15 .mu.m thick to the
jig, the generating amount of particles was increased and the
treatment became difficult. Also, in the jig after use, many cracks
were observed and a part of the polysilicon film was peeled
off.
ADVANTAGE OF THE INVENTION
[0024] In the silica glass jig for semiconductor industry of the
present invention, many dimple-form concave portions having a width
of from 20 to 300 .mu.m exist on the surface thereof, there are
grooves having a width of from 0.5 to 50 .mu.m at an interval of
from 20 to 300 .mu.m on the surface, and small projections having a
width of from 1 to 50 .mu.m and a height of from 0.1 to 10 .mu.m
are uniformly distributed between the grooves and in the grooves,
whereby the generation of particles of, for example, a polysilicon
film, etc., during the use thereof is reduced, the formation of
cracks is less, and the jig can be used with a prolonged life. The
above-described silica glass jig can be produced by a simple method
of roughening by machining, which has hitherto been used, and, in
succession, treating with a treating solution containing hydrogen
fluoride and ammonium fluoride of specific concentrations, and the
industrial value thereof is high.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a photograph of 100 magnifications of the surface
of a silica glass jig of the present invention by a scanning
electron microscope.
[0026] FIG. 2 is a photograph of 100 magnifications of the surface
of a silica glass jig of prior art, which is obtained by
sandblasting and by an etching treatment using hydrogen fluoride,
by a scanning electron microscope.
[0027] FIG. 3 is a photograph of 100 magnifications of the surface
of a silica glass jig treated with the first processing solution,
by a scanning electron microscope.
[0028] FIG. 4 is a photograph of 100 magnifications of the surface
of a silica glass jig treated with the first and second processing
solutions, by a scanning electron microscope.
* * * * *