U.S. patent application number 14/138720 was filed with the patent office on 2014-04-24 for sputtering target material, silicon-containing film forming method, and photomask blank.
This patent application is currently assigned to Shin-Etsu Chemical Co., Ltd.. The applicant listed for this patent is Shin-Etsu Chemical Co., Ltd.. Invention is credited to Yukio INAZUKI, Hideo KANEKO, Hiroki YOSHIKAWA.
Application Number | 20140110256 14/138720 |
Document ID | / |
Family ID | 44905542 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140110256 |
Kind Code |
A1 |
KANEKO; Hideo ; et
al. |
April 24, 2014 |
SPUTTERING TARGET MATERIAL, SILICON-CONTAINING FILM FORMING METHOD,
AND PHOTOMASK BLANK
Abstract
Provided is a silicon target material in which particles are not
easily generated during a sputtering process and to form a
low-defect (high quality) silicon-containing film. A silicon target
material having a specific resistance of 20 .OMEGA.cm or more at
room temperature is used for forming a silicon-containing film. The
silicon target material may be polycrystalline or noncrystalline.
However, when the silicon target material is single-crystalline, a
more stable discharge state can be obtained. Also, a single-crystal
silicon in which crystals are grown by an FZ method is a preferable
material as a highly-pure silicon target material because its
content of oxygen is low. Further, a target material having n-type
conductivity and containing donor impurities is preferable to
obtain stable discharge characteristics. Only a single or a
plurality of silicon target materials according to the present
invention may be used for sputtering film formation of the
silicon-containing film.
Inventors: |
KANEKO; Hideo; (Niigata,
JP) ; INAZUKI; Yukio; (Niigata, JP) ;
YOSHIKAWA; Hiroki; (Niigata, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shin-Etsu Chemical Co., Ltd. |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
Shin-Etsu Chemical Co.,
Ltd.
Chiyoda-ku
JP
|
Family ID: |
44905542 |
Appl. No.: |
14/138720 |
Filed: |
December 23, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13273656 |
Oct 14, 2011 |
8647795 |
|
|
14138720 |
|
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Current U.S.
Class: |
204/298.13 |
Current CPC
Class: |
C23C 14/0036 20130101;
C23C 14/3414 20130101; C23C 14/564 20130101; G03F 1/54 20130101;
C23C 14/0676 20130101 |
Class at
Publication: |
204/298.13 |
International
Class: |
C23C 14/34 20060101
C23C014/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 22, 2010 |
JP |
2010-237114 |
Claims
1-24. (canceled)
25. A target material for sputtering, comprising a silicon target
material having a high resistance used for forming a
silicon-containing film by a DC sputtering method, wherein a
specific resistance of the silicon target material is 20 .OMEGA.cm
or more at room temperature.
26. The target material for sputtering according to claim 25,
wherein the conductivity of the silicon target material is
n-type.
27. The target material for sputtering according to claim 26,
wherein the silicon target material is single-crystalline.
28. The target material for sputtering according to claim 27,
wherein the silicon target material is a single-crystal silicon in
which crystals are grown by an FZ method.
29. The target material for sputtering according to claim 25,
wherein the silicon target material is single-crystalline.
30. The target material for sputtering according to claim 29,
wherein the silicon target material is a single-crystal silicon in
which crystals are grown by an FZ method.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a technique for forming a
silicon-containing film. More specifically, the present invention
relates to a sputtering target material for forming a
silicon-containing film, a method for forming a high-quality
silicon-containing film using the same, and a photomask having the
high-quality silicon-containing film.
[0003] 2. Description of the Related Art
[0004] Recent years, in the field of semiconductor processing
technology, the technology for miniaturization of a wiring pattern
to constitute a circuit and miniaturization of a contact hole
pattern for inter-layer wiring to constitute a cell has been
increasingly desired because of miniaturization of a circuit
pattern due to higher integration of large-scale integrated
circuits. To meet such a demand, the wavelength of an exposure
light used for photolithography is shortened from an i-line (365
nm) to a KrF excimer laser (248 nm). An ArF excimer laser (193 nm)
is used for leading-edge industrial processing.
[0005] In the normally-used photolithography, a photopattern is
formed by passing a light generated by a light source through a
photomask, irradiating it to a resist film, and performing a
pattern exposure on the resist film formed to process a substrate
to be processed. At this time, the photomask is used for forming
the above-described minute patterns and is further used as an
original drawing for processing patterns. Accordingly, the
photomask is required to have extremely high accuracy. Thus, a film
for constituting a blank (photomask blank) used for manufacturing a
photomask is required to be a film having high processing accuracy
and extremely low defects.
[0006] As a material for a light-shielding film which is one of
composition elements of the photomask blank, a silicon-based
material from which a film having high processing accuracy can be
easily obtained has started drawing attention. The silicon-based
material has been conventionally used as a material for forming a
halftone phase shift film in manufacturing a halftone phase shift
mask (see Japanese Patent Laid-Open No. 7-140635). An optical film
formed from the silicon-based material containing nitrided or
oxidized molybdenum has high controllability of light transmission
characteristics. Further, high processing accuracy can be easily
obtained.
[0007] As compared with a chromium-based material conventionally
used for forming the light-shielding film, such a silicon-based
material has excellent light-shielding characteristics for an
exposure light of 200 nm or less and can be processed by fluorine
dry etching which does not easily damage a resist pattern (see
Japanese Patent Laid-Open No. 2007-241065).
[0008] Also, a silicon-based material film has an advantage in
combining a technique for using an etching mask for processing with
higher accuracy. In other words, the light-shielding film of the
silicon-based material is processed using the chromium-based
material as an etching mask, a processing error due to pattern
dependency or side etching can be reduced as compared with when the
light-shielding film of the chromium-based material is processed
using the silicon-based material as an etching mask (see Japanese
Patent Laid-Open No. 2007-241060). Thus, the light-shielding film
of the silicon-based material has shown great promise as the next
generation of the light-shielding film instead of the conventional
light-shielding film of the chromium-based material.
[0009] For forming a silicon-based material film, a sputtering
target of the silicon-based material is usually used. As the
sputtering target of such a silicon-based material, a stand-alone
silicon (see Japanese Patent Laid-Open No. 2004-301993), a
silicon-based target containing a transition metal used for forming
a silicon-based material film containing the transition metal are
used. When a sputtering target of the stand-alone silicon is used
for forming a film, particles are generated during a sputtering
process because the electrical conductivity of the target material
is low and therefore particle defects are easily occurred on an
obtained optical film.
[0010] Some techniques for suppressing the occurrence of particles
from the sputtering target of the stand-alone silicon have been
suggested. For example, Japanese Patent Laid-Open No. 2002-72443
suggests using a sputtering target of a single-crystal silicon.
Japanese Patent Laid-Open No. 2003-322955 suggests using a
sputtering target of which a specific resistance is lowered by
adding donor impurities or acceptor impurities in a stand-alone
silicon.
SUMMARY OF THE INVENTION
[0011] When a pattern size of a photomask is 45 nm or less which is
extremely minute, a photomask blank used for manufacturing such a
photomask is required to have lower defectivity (higher quality).
Thus, when a silicon-based material film is formed using a target
of a silicon-based material in which particles are easily generated
during sputtering in manufacturing the photomask blank, a technique
for suppressing defects caused by the particles more effectively is
desired.
[0012] The present invention has been made in view of such a
problem. An object of the present invention is to provide a silicon
target material in which particles are not easily generated during
a sputtering process and to provide a lower-defect (high quality)
silicon-containing film formed using the same.
[0013] To solve the above-described problem, a target material for
sputtering according to an aspect of the invention includes a
silicon target material used for forming a silicon-containing
material in which a specific resistance of the silicon target
material is 20 .OMEGA.cm or more at room temperature.
[0014] It is preferred that the conductivity of the silicon target
material is n-type. It is also preferred that the silicon target
material is single-crystalline. For example, the silicon target
material may be a single-crystal silicon in which crystals are
grown by an FZ method.
[0015] According to another aspect of the present invention, a
method for forming a silicon-containing film includes forming the
silicon-containing film by a sputtering method using a silicon
target material having a specific resistance of 20 .OMEGA.cm or
more at room temperature.
[0016] It is preferred that the conductivity of the silicon target
material is n-type. It is also preferred that the silicon target
material is single-crystalline. The silicon-containing film may be
formed in an atmosphere containing reactive gas containing at least
one of oxygen and nitrogen. Preferably, the sputtering method is a
DC sputtering method.
[0017] A photomask blank according to a further aspect of the
present invention includes the silicon-containing film formed by
the method as described above.
[0018] The silicon-containing film is formed by sputtering using
the silicon target material having the specific resistance of 20
.OMEGA.cm or more at room temperature according to the present
invention. Therefore, the discharge characteristics are improved
during a film formation process, and thus the number of particle
defects in the silicon-containing film is reduced.
[0019] Thus, a low-defect and high-quality silicon-containing film
can be provided to be usable as a light-shielding film or a phase
shift film of a photomask blank.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] Particles are generated during sputtering using a silicon
target material usually because of arc discharge on a target. In
this regard, Japanese Patent Laid-Open No. 2003-322955 discloses
that, when the conductivity of the target is small, the voltage is
not easily applied on the surface of the target and the discharge
becomes unstable, so that arc discharge is easily generated on the
target and thus particles are easily generated. In the invention
disclosed in Japanese Patent Laid-Open No. 2003-322955, a silicon
target having a specific resistance of 0.1 .OMEGA.cm or less is
used for reducing the occurrence of such particles.
[0021] To pursue the further reduction of defects in an optical
film caused by particles generated in a sputtering process, the
inventors have found out that a silicon-containing film having low
defects caused by the particles can be obtained by using a silicon
target of high resistance (low conductivity) contrary to the
invention disclosed in Japanese Patent Laid-Open No. 2003-322955 in
which a silicon target of low resistance (high conductivity) having
a specific resistance of 0.1 .OMEGA.cm or less is used.
[0022] According to the present invention, a sputtering target
material having relatively high resistance (low conductivity) and
having a specific resistance of 20 .OMEGA.cm or more at room
temperature is used as a silicon target material used for forming a
silicon-containing film. In other words, according to the present
invention, a specific resistance is selected contrary to the idea
disclosed in Japanese Patent Laid-Open No. 2003-322955 in which the
occurrence of particles is reduced by suppressing the arc discharge
generated due to high resistance of the target material surface. By
forming a film using a sputtering target material of a specific
resistance of 20 .OMEGA.cm or more at room temperature, a
silicon-containing film having low particle defects can be obtained
as described later.
[0023] It is preferred that such a silicon target material has
n-type conductivity in which a small amount of a donor element such
as phosphorus and arsenic in view of discharge stability. When a
single-crystalline is used as the silicon target material, the
occurrence of particles is suppressed effectively because a grain
boundary is not included. Especially, a single-crystal silicon in
which crystals are grown by an FZ method has an extremely small
content of oxygen, and is suitable as a silicon target material of
the present invention.
[0024] A silicon-containing film of the present invention will be
described below as an optical film for constituting a photomask
blank. However, the present invention is not limited thereto.
[0025] For example, the silicon-containing film is used as a phase
shift film or a light-shielding film of the photomask blank. Here,
the light-shielding film means an optical film in which a light
transmitting an area where the light-shielding film is provided
does not substantially contribute to an exposure light when being
used as a photomask. Thus, a total of the optical concentration for
an exposure light of a light absorbing film formed on a transparent
substrate is 2.0 or more, more typically 2.5 or more.
[0026] For example, such a silicon-containing film includes a
stand-alone silicon film or film containing silicon, oxygen, and
nitrogen as main components. The silicon-containing film is formed
by reactive sputtering of a target material containing a silicon
atom in an atmosphere containing reactive gas to which oxygen and
nitrogen are added as necessary. As the sputtering method, a DC
sputtering method by which the occurrence of particles is reduced
and a high-quality film is easily obtained is preferably used.
[0027] As the target material used for forming the
silicon-containing film, a target material of a stand-alone silicon
(silicon target material) or a target material of a silicon-based
material containing a transition metal may be used in accordance
with the composition of the silicon-containing film.
[0028] A silicon target material which does not substantially
contain a transition metal is used not only when the
silicon-containing film which does not contain the transition metal
is formed, but also when a content ratio of the transition metal
relative to silicon is changed in the depth direction of the film
or when a content ratio of the transition metal relative to silicon
is extremely low.
[0029] In the leading-edge lithography method for semiconductor
processing, an ArF excimer laser is used as an exposure light. To
ensure a transmission required for a phase shift film in a
wavelength area of the exposure light, a material having a content
ratio of a transition metal which is lower than a
conventionally-used transition metal-containing silicon material is
needed to form the film. A chromium-based material is
conventionally used as a material for a light-shielding film.
However, it has becoming obvious that a silicon-based material is
superior in light of the light-shielding property and processing
performance. Also, it has been known that the chemical resistant
property is improved as a content ratio of silicon is higher.
[0030] Under such circumstances, the need for using a stand-alone
silicon target material (silicon target material) has been
increased when a silicon-containing film is formed by
sputtering.
[0031] However, when the film is formed by reactive sputtering in
accordance with the DC sputtering method using the stand-alone
silicon target material (silicon target material), the discharge
becomes unstable due to the low conductivity of the target material
and abnormal discharge is easily occurred. It has been known that
the silicon-containing film formed in such a discharge state
contains many defects caused by particles (particle defects). For
such reasons, in the invention disclosed in Japanese Patent
Laid-Open No. 2003-322955, the film stability and the occurrence of
particles are reduced to improve the productivity by using the
silicon target material (having a low resistance) of which the
conductivity is enhanced by adding impurities such as a donor and
an acceptor.
[0032] The inventors has confirmed the following fact in the
process of studying a silicon-containing film having low particle
defects formed by DC sputtering using a silicon target material.
Firstly, when a silicon target material having a specific
resistance of 1 .OMEGA.cm or less is used, the stable discharge is
easily obtained and the abnormal discharge is not easily occurred
as described in a conventional report. When a silicon target
material having a specific resistance of around 15 .OMEGA.cm is
used, the stable discharge is extremely difficult to be obtained.
When the specific resistance is higher than 15 .OMEGA.cm, the
discharge characteristics is improved. When the specific resistance
is 20 .OMEGA.cm or more, the number of particle defects in the
formed silicon-containing film is reduced. When the specific
resistance of the silicon target material is 50 .OMEGA.cm or more,
the number of particle defects is remarkably reduced.
[0033] The reason why the number of particle defects is reduced by
using the silicon target material having a high specific resistance
is not fully clarified. However, the inventors estimate the reasons
as follows.
[0034] During a sputtering film formation process, high-energy
particles (plasma) are irradiated to a target. When the high-energy
particles collide with semiconductor crystals such as silicon,
carriers (electrons and holes) are generated. Thus, in forming a
film by sputtering using a silicon target, carriers are generated
in the target.
[0035] The generated carriers are moved (diffused) in the target
due to the applied voltage. When the diffused carriers collide with
silicon crystal gratings, carriers are further generated. Since
carries are repeatedly generated as described above, the number of
carriers is gradually increased.
[0036] A distance where the carriers generated once are diffused in
the silicon crystals becomes longer as the concentration of
impurities contained in the target material is lower. Accordingly,
the carriers are remarkably increased as the specific resistance of
the silicon target material is higher. Consequently, the silicon
target material having a high specific resistance has relatively
high conductivity in the plasma, and thus the abnormal discharge is
not easily occurred.
[0037] On the other hand, a silicon target material having a low
specific resistance contains a relatively large amount of
impurities such as boron (B) serving as an acceptor and phosphorus
(P) serving as a donor in silicon crystals. Therefore, the
conductivity is enhanced by carriers generated due to these
impurities, and thus the discharge stability is improved.
[0038] However, the surface of the silicon target material having
the low specific resistance easily reacts with reactive gas in an
atmosphere. Thus, a film having a high resistance such as an oxide
film is easily formed on the surface of the target to be relatively
thick.
[0039] To the contrary, the surface of the silicon target having
the relatively high specific resistance according to the present
invention does not easily react with the reactive gas in the
atmosphere. Even when the film having the high resistance such as
the oxide film is formed on the surface of the target, its
thickness is relatively thin. Accordingly, the stable discharge
state can be easily maintained until termination of sputtering film
formation. The above-described mechanism is merely on the basis of
the speculation of the inventors. Thus, the present invention is
not limited thereto.
[0040] The silicon target material according to the present
invention may be polycrystalline or noncrystalline. However, when
the silicon target material is single-crystalline, a more stable
discharge state can be provided because there is no crystal grain
boundary. Also, a single-crystal silicon in which crystals are
grown by the FZ method is a preferable material as a highly-pure
silicon target material because its content of oxygen is low.
[0041] The silicon target material according to the present
invention has a relatively high specific resistance, the
concentration of a dopant contained in silicon is low. Therefore,
as long as the specific resistance is 20 .OMEGA.cm or more, the
advantageous effects of the present invention are not impaired
depending on the type (conductivity type) and the concentration
(conductivity) of the dopant. However, in order to obtain the
stable discharge characteristics, an n-type dopant containing donor
impurities is preferable.
[0042] A single or a plurality of silicon target materials
according to the present invention are used for sputtering film
formation of the silicon-containing film. Instead, a silicon target
material and a target material containing a transition metal and
silicon may be simultaneously used, or a silicon target material
and a transition metal target material may be simultaneously
used.
[0043] When the silicon target material and the target material
containing the transition metal and silicon are simultaneously
used, the composition of the latter target material may be
appropriately selected depending on the composition of a target
film. At this time, the transition metal does not required to be
one type. When a plurality of types of transition metals are
contained, the content ratio of each transition metal and silicon
may be different for every transition metal. Such a target material
is usually manufactured by a sintering method.
[0044] For example, the transition metal contained in the target
material for forming the light-shielding film or the phase shift
film may be titanium, vanadium, cobalt, nickel, zirconium, niobium,
molybdenum, hafnium, tantalum, and tungsten. Molybdenum is
preferable in view of dry etching processing characteristics of the
obtained film.
[0045] The silicon-containing film according to the present
invention is formed by the sputtering method using the
above-described silicon target material having the specific
resistance of 20 .OMEGA.cm or more at room temperature. Such a
silicon-containing film may be silicon oxide, silicon nitride,
silicon oxynitride, transition metal silicon oxide, transition
metal silicon nitride, and transition metal silicon oxynitride.
Such a film may contain light elements such as carbon, helium, and
hydrogen.
[0046] A ratio of the transition metal relative to the silicon
contained in the silicon-containing film can be adjusted by the
target material used for forming the film and the electric power
applied to the target material. Also, a content of the light
elements such as oxygen, nitrogen, and carbon can be controlled by
adjustment of the later-described sputtering gas.
[0047] A composition of the silicon-containing film according to
the present invention can be appropriately adjusted by a function
of the target film. A preferred composition of a film having a high
light-shielding function in the light-shielding film consists
essentially of 10 atom % or more and 95 atom % or less,
specifically 30 atom % or more and 95 atom % or less of silicon, 0
atom % or more and 50 atom % or less, specifically 0 atom % or more
and 30 atom % or less of oxygen, 0 atom % or more and 40 atom % or
less, specifically 0 atom % or more and 20 atom % or less of
nitrogen, 0 atom % or more and 20 atom % or less, specifically 0
atom % or more and 5 atom % or less of carbon, and 0 atom % or more
and 35 atom % or less, specifically 1 atom % or more and 20 atom %
or less of transition metal.
[0048] A preferred composition of a film having an antireflection
function in the light-shielding film consists essentially of 10
atom % or more and 80 atom % or less, specifically 30 atom % or
more and 50 atom % or less of silicon, 0 atom % or more and 60 atom
% or less, specifically 0 atom % or more and 40 atom % or less of
oxygen, 0 atom % or more and 57 atom % or less, specifically 20
atom % or more and 50 atom % or less of nitrogen, 0 atom % or more
and 20 atom % or less, specifically 0 atom % or more and 5 atom %
or less of carbon, and 0 atom % or more and 35 atom % or less,
specifically 1 atom % or more and 20 atom % or less of transition
metal.
[0049] A preferred composition of a film functioning as a phase
shift film for absorbing light consists essentially of 10 atom % or
more and 95 atom % or less, specifically 20 atom % or more and 95
atom % or less of silicon, 0 atom % or more and 60 atom % or less,
specifically 0 atom % or more and 40 atom % or less of oxygen, 0
atom % or more and 50 atom % or less, specifically 0 atom % or more
and 40 atom % or less of nitrogen, 0 atom % or more and 20 atom %
or less, specifically 0 atom % or more and 5 atom % or less of
carbon, and 0 atom % or more and 35 atom % or less, specifically 1
atom % or more and 20 atom % or less of transition metal.
[0050] The present invention is not specifically restricted
relating to the sputtering method. However, the DC sputtering is
preferable. The DC sputtering may be DC sputtering or pulsed DC
sputtering.
[0051] The silicon-containing film according to the present
invention is formed by reactive sputtering, for example, in an
atmosphere containing reactive gas containing at least one of
oxygen and nitrogen using the silicon target material having the
specific resistance of 20 .OMEGA.cm or more at room temperature.
For example, the gas containing oxygen may be oxygen gas, nitric
oxide gas (the oxidation number of nitrogen is not specifically
limited), carbon monoxide gas, and carbon dioxide gas. The gas
containing nitrogen may be nitrogen gas, nitric oxide gas (the
oxidation number of nitrogen is not specifically limited), and
ammonia gas. Inert gas such as argon, xenon, and helium may be
simultaneously used with these gases.
[0052] The sputtering gas is appropriately adjusted to obtain the
composition of the target film and the discharge stability. For
example, a preferred range of gas pressure is 0.01 Pa to 10 Pa.
[0053] The photomask blank according to the present invention
includes the above-described silicon-containing film according to
the present invention as an optical film such as a light-shielding
film and a phase shift film. The silicon-containing film according
to the present invention is effective as an auxiliary film such as
a hard mask film for highly accurate etching processing of the
light-shielding film and an etching stopper film provided between a
transparent substrate and the light-shielding film.
[0054] Contrary to the conventional silicon target material, the
resistance of the silicon target material according to the present
invention is selected to be relatively high. When the sputtering
film formation is performed using such a silicon target material,
the occurrence of particles is suppressed and thus a low-defect
silicon-containing film can be obtained. Such a silicon-containing
film with high quality can be used as an optical film for
constituting the photomask blank and also used for other various
purposes.
EXAMPLE 1
[0055] Four substrates for a quart photomask having a 152 mm square
were prepared, and a MoSiON film (Mo:Si:O:N=1:4:1:4) having the
film thickness of 76 nm was formed on each substrate by the DC
sputtering method. A single-crystal silicon target material having
the n-type conductivity and having the specific resistance of 60
.OMEGA.cm at room temperature and a MoSi sintering target material
(Mo:Si=1:2) were used as a target. In addition, argon gas, nitrogen
gas, and oxygen gas were used as sputtering gas.
[0056] Defects of the MoSiON film obtained as described above were
measured by Magics2351 (registered trademark) manufactured by
Lasertec. The number of the defects having 0.2 .mu.m or more is
eight on average per one film formation substrate.
EXAMPLE 2
[0057] Under the same film formation condition as in Example 1
except that a single-crystal silicon having the n-type conductivity
and having the specific resistance of 200 .OMEGA.cm at room
temperature was used as the silicon target material, a MoSiON film
was formed on each of four substrates for photomask. When defects
were measured after forming the film similarly to Example 1, the
number of the defects having 0.2 .mu.m or more is six on average
per one film formation substrate.
[Comparison 1]
[0058] Under the same film formation condition as in Example 1
except that a polycrystalline silicon having the p-type
conductivity and having the specific resistance of 0.001 .OMEGA.cm
at room temperature was used as the silicon target material, a
MoSiON film was formed on each of four substrates for photomask.
When defects were measured after forming the film similarly to
Example 1, the number of the defects having 0.2 .mu.m or more is 21
on average per one film formation substrate.
[Comparison 2]
[0059] Under the same film formation condition as in Example 1
except that a single-crystal silicon having the p-type conductivity
and having the specific resistance of 15 .OMEGA.cm at room
temperature was used as the silicon target material, a MoSiON film
was formed. The stable discharge was not obtained from the silicon
target material.
[0060] The silicon-containing film is formed by sputtering using
the silicon target material having the specific resistance of 20
.OMEGA.cm or more at room temperature according to the present
invention. Therefore, the discharge characteristics are improved
during the film formation process, and thus the number of particle
defects in the silicon-containing film is reduced. Thus, the
low-defect and high-quality silicon-containing film can be provided
to be usable as the light-shielding film or the phase shift film of
the photomask blank.
* * * * *