U.S. patent application number 16/742786 was filed with the patent office on 2020-05-14 for mask blank, transfer mask, method for manufacturing transfer mask, and method for manufacturing semiconductor device.
This patent application is currently assigned to HOYA CORPORATION. The applicant listed for this patent is HOYA CORPORATION. Invention is credited to Osamu NOZAWA, Ryo OHKUBO, Hiroaki SHISHIDO.
Application Number | 20200150524 16/742786 |
Document ID | / |
Family ID | 56919653 |
Filed Date | 2020-05-14 |
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United States Patent
Application |
20200150524 |
Kind Code |
A1 |
NOZAWA; Osamu ; et
al. |
May 14, 2020 |
MASK BLANK, TRANSFER MASK, METHOD FOR MANUFACTURING TRANSFER MASK,
AND METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE
Abstract
A mask blank is provided which comprises a transparent
substrate, an etching mask formed on the transparent substrate, and
a light shielding film formed on the etching mask film. The mask
blank may also include a light-semitransmissive film formed between
the transparent substrate and the etching mask film. The etching
mask film contains chromium and carbon, and the light shielding
film contains chromium and oxygen. A C1s narrow spectrum of the
etching mask film as obtained by X-ray photoelectron spectroscopy
analysis has a maximum peak at a binding energy of not less than
282 eV and not more than 284 eV.
Inventors: |
NOZAWA; Osamu; (Tokyo,
JP) ; SHISHIDO; Hiroaki; (Tokyo, JP) ; OHKUBO;
Ryo; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HOYA CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
HOYA CORPORATION
Tokyo
JP
|
Family ID: |
56919653 |
Appl. No.: |
16/742786 |
Filed: |
January 14, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15553634 |
Aug 25, 2017 |
10571797 |
|
|
PCT/JP2015/085997 |
Dec 24, 2015 |
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16742786 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 14/0641 20130101;
G03F 1/80 20130101; G03F 7/2002 20130101; C23C 14/14 20130101; G03F
1/78 20130101; H01L 21/3081 20130101; G03F 1/54 20130101; C23C
14/06 20130101; C23C 14/0635 20130101; H01L 21/3086 20130101; G03F
1/32 20130101 |
International
Class: |
G03F 1/32 20060101
G03F001/32; H01L 21/308 20060101 H01L021/308; G03F 7/20 20060101
G03F007/20; G03F 1/78 20060101 G03F001/78; G03F 1/80 20060101
G03F001/80; G03F 1/54 20060101 G03F001/54; C23C 14/06 20060101
C23C014/06; C23C 14/14 20060101 C23C014/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2015 |
JP |
2015-055902 |
Claims
1. A mask blank comprising: a transparent substrate; an etching
mask film formed on the transparent substrate; and a light
shielding film formed on the etching mask film, wherein the etching
mask film contains chromium and carbon, and wherein a C1s narrow
spectrum of the etching mask film as obtained by X-ray
photoelectron spectroscopy analysis has a maximum peak at a binding
energy of not less than 282 eV and not more than 284 eV, and
wherein the light shielding film contains chromium and oxygen.
2. The mask blank according to claim 1, wherein the total content
of oxygen and nitrogen in the etching mask film is 5 atom % or
less.
3. The mask blank according to claim 1, wherein the oxygen content
in the light shielding film is 10 atom % or more.
4. The mask blank according to claim 1, wherein a O1s narrow
spectrum of the etching mask film as obtained by X-ray
photoelectron spectroscopy analysis is not more than the detection
lower limit.
5. The mask blank according to claim 1, wherein a N1s narrow
spectrum of the etching mask film as obtained by X-ray
photoelectron spectroscopy analysis is not more than the detection
lower limit.
6. The mask blank according to claim 1, wherein a thickness of the
etching mask film is 14 nm or less.
7. The mask blank according to claim 1, wherein a
light-semitransmissive film is provided between the transparent
substrate and the etching mask film.
8. The mask blank according to claim 7, wherein the
light-semitransmissive film contains silicon and nitrogen.
9. A transfer mask comprising: a transparent substrate; an etching
mask film formed on the transparent substrate; and a light
shielding film formed on the etching mask film, wherein the
transparent substrate has a transfer pattern that comprises an
etching pattern, and wherein the etching mask film and the light
shielding film have a light shielding band pattern, and wherein the
etching mask film contains chromium and carbon, and wherein a C1s
narrow spectrum of the etching mask film as obtained by X-ray
photoelectron spectroscopy analysis has a maximum peak at a binding
energy of not less than 282 eV and not more than 284 eV, and
wherein the light shielding film contains chromium and oxygen.
10. The transfer mask according to claim 9, wherein the total
content of oxygen and nitrogen in the etching mask film is 5 atom %
or less.
11. The transfer mask according to claim 9, wherein the oxygen
content in the light shielding film is 10 atom % or more.
12. The transfer mask according to claim 9, wherein a O1s narrow
spectrum of the etching mask film as obtained by X-ray
photoelectron spectroscopy analysis is not more than the detection
lower limit.
13. The transfer mask according to claim 9, wherein a N1s narrow
spectrum of the etching mask film as obtained by X-ray
photoelectron spectroscopy analysis is not more than the detection
lower limit.
14. A transfer mask comprising: a transparent substrate; a
light-semitransmissive film formed on the transparent substrate; an
etching mask film formed on the light-semitransmissive film; and a
light shielding film formed on the etching mask film, wherein the
light-semitransmissive film has a transfer pattern, and wherein the
etching mask film and the light shielding film have a light
shielding band pattern, and wherein the light-semitransmissive film
contains silicon, and wherein the etching mask film contains
chromium and carbon, and wherein a C1s narrow spectrum of the
etching mask film as obtained by X-ray photoelectron spectroscopy
analysis has a maximum peak at a binding energy of not less than
282 eV and not more than 284 eV, and wherein the light shielding
film contains chromium and oxygen.
15. The transfer mask according to claim 14, wherein the total
content of oxygen and nitrogen in the etching mask film is 5 atom %
or less.
16. The transfer mask according to claim 14, wherein the oxygen
content in the light shielding film is 10 atom % or more.
17. The transfer mask according to claim 14, wherein a O1s narrow
spectrum of the etching mask film as obtained by X-ray
photoelectron spectroscopy analysis is not more than the detection
lower limit.
18. The transfer mask according to claim 14, wherein a N1s narrow
spectrum of the etching mask film as obtained by X-ray
photoelectron spectroscopy analysis is not more than the detection
lower limit.
19. A method for manufacturing a semiconductor device, comprising
an exposure transfer in which the transfer mask according to claim
9 is used to transfer the transfer pattern onto a semiconductor
substrate by a lithographic method.
20. A method for manufacturing a semiconductor device, comprising
an exposure transfer in which the transfer mask according to claim
14 is used to transfer the transfer pattern onto a semiconductor
substrate by a lithographic method.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/886,634, filed Aug. 25, 2017, the contents
of which is incorporated herein by reference in its entirety and
which is a National Stage application of International Application
No. PCT/JP2015/085997, filed Dec. 24, 2015, the contents of which
is incorporated herein by reference in its entirety and which
claims priority to Japanese Patent Application No. 2015-055902,
filed Mar. 19, 2015.
TECHNICAL FIELD
[0002] The present disclosure relates to a mask blank, a transfer
mask, a method for manufacturing a transfer mask, and a method for
manufacturing a semiconductor device.
BACKGROUND ART
[0003] In a manufacturing process of a semiconductor device, a fine
pattern is generally formed using a photolithographic method. In
the formation of the fine pattern, multiple substrates, which are
referred to as transfer masks, are usually used. The transfer mask
is formed by providing the fine pattern comprised of a metal thin
film, etc. on a generally transparent glass substrate. The
photolithographic method is also used in the manufacture of the
transfer mask.
[0004] Refinement of a pattern for the semiconductor device
requires shortening of a wavelength of an exposure light source
used in photolithography, in addition to the refinement of a mask
pattern formed in the transfer mask. Nowadays, the exposure light
sources used in the manufacture of semiconductor devices are
shifting from KrF excimer lasers (wavelength: 248 nm) to ArF
excimer lasers (wavelength: 193 nm), that is, shorter wavelength
light sources are increasingly used.
[0005] The known types of transfer masks include a half tone phase
shift mask, in addition to a conventional binary mask including a
light shielding film pattern made of a chromium-based material on a
transparent substrate. The half tone phase shift mask includes a
light-semitransmissive film pattern on the transparent substrate.
The light-semitransmissive film (half tone phase shift film) has
functions to transmit light at an intensity not substantially
contributing to the light exposure and to generate a predetermined
phase difference between the light transmitted through the
light-semitransmissive film and the light transmitted through the
air for the same distance, thereby generating a so-called phase
shift effect.
[0006] Generally, an outer peripheral region of the transfer mask
outside the region where a transfer pattern is formed is required
to ensure optical density (OD) of not less than a predetermined
value such that, upon the exposure transfer to a resist film on a
semiconductor wafer using an exposure apparatus, the resist film
will not be affected by the exposure light transmitted through the
outer peripheral region. Usually, the outer peripheral region of
the transfer mask desirably has OD of 3 or more, and at least about
2.8 of OD is necessary. However, the light-semitransmissive film of
the half tone phase shift mask has a function to transmit the
exposure light at a predetermined transmittance, and it is
difficult to ensure the optical density required in the outer
peripheral region of the transfer mask with the
light-semitransmissive film alone. Therefore, as with a phase shift
mask blank disclosed in Patent Document 1, a light shielding film
(light blocking film) is laminated onto a semitransparent film
having predetermined phase shift amount and transmittance with
respect to the exposure light to ensure the predetermined optical
density in a laminated structure of the semitransparent film and
the light shielding film.
[0007] There is also a phase shift mask blank as disclosed in
Patent Document 2, in which a light shielding film provided on a
phase shift film is made of a material containing a transition
metal and silicon. In this phase shift mask blank, the material
containing a transition metal and silicon is also used as a
material for forming the phase shift film, as is conventionally
done. Therefore, it is difficult to ensure etching selectivity
between the phase shift film and the light shielding film in the
dry etching. The phase shift mask blank of Patent Document 2
includes, between the phase shift film and the light shielding
film, an etching stopper film made of a material containing
chromium. It further includes, on the light shielding film, an
etching mask film made of the material containing chromium.
PRIOR ART DOCUMENTS
Patent Documents
[0008] Patent Document 1: Japanese Patent Application Publication
2007-033469 [0009] Patent Document 2: Japanese Patent Application
Publication 2007-241065 [0010] Patent Document 3: Japanese Patent
Application Publication 2007-241136
SUMMARY OF THE DISCLOSURE
Problems to be Solved
[0011] A transfer mask which includes a transfer pattern formed in
a light-semitransmissive film (phase shift film) having a property
of transmitting the exposure light at a predetermined
transmittance, such as the half tone phase shift mask, needs to
have a light shielding band formed in an outer peripheral region
(blind area) outside a region where the transfer pattern is formed.
Thus, a mask blank for manufacturing the half tone phase shift mask
(hereinafter simply referred to as a phase shift mask) is generally
configured such that the light-semitransmissive film and the light
shielding film are laminated on a transparent substrate, as
disclosed in Patent Document 1. However, when manufacturing a
transfer mask from such a mask blank, the dry etching using as a
mask a resist pattern having a transfer pattern to be formed in the
phase shift film cannot be performed directly on the
light-semitransmissive film.
[0012] In the general phase shift mask, the phase shift film is
provided with a fine pattern, and the light shielding film is
provided with a light shielding pattern for forming the light
shielding band, etc. to satisfy the predetermined optical density
in the laminated structure of the light shielding film and the
light-semitransmissive film. That is, in the phase shift mask, the
phase shift film and the light shielding film have respective
different patterns formed therein. Thus, for the mask blank of a
laminated structure which includes the light shielding film
provided on and in direct contact with the phase shift film,
materials with different etching properties are used for the phase
shift film and the light shielding film, respectively. The phase
shift film often needs to have not only a function to transmit the
light at the predetermined transmittance but also a function to
control the phase of the light transmitted through the phase shift
film. A material containing silicon is often used as a material for
the phase shift film since it easily provides the optical
properties required for such a phase shift film.
[0013] A thin film made of the material containing silicon is
generally patterned by the dry etching using a fluorine-based gas.
The material having etching durability in the dry etching using the
fluorine-based gas includes the material containing chromium. A
thin film made of the material containing chromium can be patterned
by the dry etching using a mixed gas of a chlorine-based gas and an
oxygen gas (hereinafter referred to as an oxygen-containing
chlorine-based gas). The thin film made of the material containing
silicon has etching durability in the dry etching using the
oxygen-containing chlorine-based gas. The thin film made of the
material containing chromium and the thin film made of the material
containing silicon are a combination by which both thin films can
obtain sufficient etching selectivity.
[0014] When a phase shift mask is manufactured from this mask
blank, the dry etching is performed on the light shielding film
using as a mask a resist pattern having a transfer pattern to be
formed in the phase shift film, so that the transfer pattern to be
formed in the phase shift film is formed earlier in the light
shielding film. Then, the dry etching is performed on the
light-semitransmissive film using as a mask the light shielding
film having this transfer pattern formed therein, so that the
transfer pattern is formed in the phase shift film. However, the
dry etching using the oxygen-containing chlorine-based gas which is
performed on the light shielding film made of the material
containing chromium has a tendency toward isotropic etching
because, for example, the etching gas contains the oxygen gas
plasma mainly composed of radicals, and thus, it is difficult to
enhance etching anisotropy.
[0015] The generally used resist film made of an organic material
has resistance to the oxygen gas plasma which is significantly
lower than the resistance to other gas plasma. Thus, if the light
shielding film made of a chromium-based material is dry-etched with
the oxygen-containing chlorine-based gas, an amount of consumption
of the resist film (a reduction amount of thickness of the resist
film during the etching) becomes large. In order to form the fine
pattern in the light shielding film with great accuracy by the dry
etching, the resist film having a predetermined thickness or more
should remain upon completion of the patterning of the light
shielding film. However, if the thickness of the resist film in
which the pattern is formed first is increased, a cross-sectional
aspect ratio of the resist pattern (a ratio of film thickness to
pattern line width) becomes too large, and thus, a phenomenon of
resist pattern collapse tends to take place. It is possible to
solve these problems by significantly reducing the thickness of the
light shielding film. However, since the light shielding film needs
to have predetermined optical density in relation to the exposure
light, it is difficult to configure the light shielding film to
have a thickness with which the problems relating to the etching
can be solved.
[0016] As described above, when a fine transfer pattern to be
formed in the light-semitransmissive film is formed in the light
shielding film by the dry etching using the oxygen-containing
chlorine-based gas, it is difficult to enhance the accuracy of
pattern shape and the in-plane CD uniformity. In forming the
transfer pattern in the light-semitransmissive film, the dry
etching using the fluorine-based gas which has a high tendency
toward anisotropic etching is applied. However, the light shielding
film in which the highly accurate formation of the fine transfer
pattern is difficult should be used as an etching mask in the dry
etching, and thus, it is difficult to form the fine transfer
pattern in the light-semitransmissive film. Therefore, as for the
mask blank including the light shielding film between the
light-semitransmissive film and the resist film made of the organic
material, what has been sought is that the transfer pattern is
finally formed in the light-semitransmissive film with high
accuracy, beginning with the resist film having the fine transfer
pattern to be formed in the light-semitransmissive film.
[0017] The mask blank disclosed in Patent Document 2 has been
devised as a means for solving the problem of the above described
mask blank. In this mask blank, a transition metal silicide-based
material that can be dry-etched with the fluorine-based gas is used
for the light shielding film which should have a predetermined
thickness or more, so that the fine pattern can be formed in the
light shielding film with high accuracy. Further, since the light
shielding film does not have etching selectivity in relation to the
phase shift film, an etching stopper film made of the
chromium-based material is provided between the phase shift film
and the light shielding film. Basically, there is no limitation on
the optical density of the etching stopper film. The etching
stopper film only has to have a thickness such that it can function
as an etching mask in the dry etching with the fluorine-based gas
for forming the fine transfer pattern in the phase shift film, so
that it can be significantly thinned compared to the conventional
light shielding film made of the chromium-based material.
Therefore, while the etching stopper film is made of the
chromium-based material that is hard to be etched in a highly
anisotropic manner, the fine pattern can be formed therein with
high accuracy.
[0018] Furthermore, the mask blank of Patent Document 2 includes an
etching mask film made of the chromium-based material on the light
shielding film. While the light shielding film can be dry-etched
with the fluorine-based gas, it includes some thickness. Thus, the
side walls of the resist film made of the organic material
significantly decline during the etching of the light shielding
film. If the etching mask film made of the chromium-based material
which has high etching durability in the dry etching with the
fluorine-based gas is used as an etching mask, the decline of
patterned sidewalls of the etching mask film can be reduced, so
that the fine pattern can be formed in the light shielding film
with higher accuracy.
[0019] However, the mask blank of Patent Document 2 has a complex
structure in which the phase shift film made of the transition
metal silicide-based material, the etching stopper film made of the
chromium-based material, the light shielding film made of the
transition metal silicide-based material, and the etching mask film
made of the chromium-based material are laminated on the
transparent substrate. The manufacture of a phase shift mask using
the mask blank of Patent Document 2 has the problem that the
manufacturing process is complex because the mask blank has the
complex structure comprised of alternately laminated films with
different etching properties. Even only the process until the
formation of the transfer pattern in the phase shift film has to
include patterning an etching mask film by the dry etching using as
a mask a resist film having a transfer pattern to be formed in a
phase shift film; patterning a light shielding film by the dry
etching using as a mask the etching mask film having the transfer
pattern; patterning an etching stopper film by the dry etching
using as a mask the light shielding film having the transfer
pattern; and patterning the phase shift film by the dry etching
using as a mask the etching stopper film having the transfer
pattern.
[0020] The mask blank disclosed in Patent Document 3 is for the
manufacture of a chromeless phase shift mask (chromeless phase
lithography (CPL) mask). This mask blank also has a complex
structure in which an etching stopper film made of a chromium-based
material, a light shielding film made of a transition metal
silicide-based material, and an etching mask film made of a
chromium-based material are laminated on a transparent substrate.
Therefore, the manufacture of the chromeless phase shift mask using
this mask blank has the problem with the complex manufacturing
process.
[0021] The present disclosure was made to solve the above existing
problems. It is an aspect of the present disclosure to provide a
mask blank which includes a light shielding film made of a material
containing chromium on a light-semitransmissive film made of a
material containing silicon, wherein a fine pattern can be formed
in the light-semitransmissive film with high accuracy. It is
another aspect of the present disclosure to provide a mask blank
which includes a light shielding film made of a material containing
chromium on a transparent substrate, wherein a fine etching pattern
can be formed in the transparent substrate with high accuracy.
Further, it is still another aspect of the present disclosure to
provide transfer masks manufactured using the above-described mask
blanks, and methods for manufacturing the transfer masks.
Additionally, it is yet another aspect of the present disclosure to
provide methods for manufacturing semiconductor devices using these
transfer masks.
EMBODIMENTS
[0022] The inventors achieved the present disclosure as a result of
the diligent study for solving the above problems. That is, in
order to solve the above problems, the present disclosure includes
the following configurations.
(Configuration 1)
[0023] A mask blank having a structure in which a
light-semitransmissive film, an etching mask film, and a light
shielding film are laminated in this order on a transparent
substrate,
[0024] wherein the light-semitransmissive film is made of a
material containing silicon,
[0025] wherein the etching mask film is made of a material
containing chromium,
[0026] wherein the light shielding film is made of a material
containing chromium and oxygen, and
[0027] wherein a ratio of the etching rate of the light shielding
film to the etching rate of the etching mask film in the dry
etching using an oxygen-containing chlorine-based gas is not less
than 3 and not more than 12.
(Configuration 2)
[0028] The mask blank according to Configuration 1, wherein the
etching mask film is made of a material which contains chromium and
further contains at least one or more elements selected from carbon
and silicon.
(Configuration 3)
[0029] The mask blank according to Configuration 1 or 2, wherein
the total content of oxygen and nitrogen in the etching mask film
is 5 atom % or less.
(Configuration 4)
[0030] The mask blank according to any one of Configurations 1 to
3, wherein the oxygen content in the light shielding film is 10
atom % or more.
(Configuration 5)
[0031] The mask blank according to any one of Configurations 1 to
4, wherein the light shielding film is made of a material which
does not substantially contain silicon.
(Configuration 6)
[0032] The mask blank according to any one of Configurations 1 to
5, wherein the light-semitransmissive film is made of a material
containing silicon and nitrogen.
(Configuration 7)
[0033] A mask blank having a structure in which an etching mask
film and a light shielding film are laminated in this order on a
transparent substrate,
[0034] wherein the etching mask film is made of a material
containing chromium,
[0035] wherein the light shielding film is made of a material
containing chromium and oxygen, and
[0036] wherein a ratio of the etching rate of the light shielding
film to the etching rate of the etching mask film in the dry
etching using an oxygen-containing chlorine-based gas is not less
than 3 and not more than 12.
(Configuration 8)
[0037] The mask blank according to Configuration 7, wherein the
etching mask film is made of a material which contains chromium and
further contains at least one or more elements selected from carbon
and silicon.
(Configuration 9)
[0038] The mask blank according to Configuration 7 or 8, wherein
the total content of oxygen and nitrogen in the etching mask film
is 5 atom % or less.
(Configuration 10)
[0039] The mask blank according to any one of Configurations 7 to
9, wherein the oxygen content in the light shielding film is 10
atom % or more.
(Configuration 11)
[0040] The mask blank according to any one of Configurations 7 to
10, wherein the light shielding film is made of a material which
does not substantially contain silicon.
(Configuration 12)
[0041] A transfer mask, wherein a first pattern including a
transfer pattern is formed in the light-semitransmissive film of
the mask blank according to any one of Configurations 1 to 6, and a
second pattern including a light shielding band pattern is formed
in the etching mask film and the light shielding film.
(Configuration 13)
[0042] A transfer mask, wherein a third pattern including a
transfer pattern comprised of an etching pattern is formed in the
transparent substrate of the mask blank according to any one of
Configurations 7 to 11, and a fourth pattern including a light
shielding band pattern is formed in the etching mask film and the
light shielding film.
(Configuration 14)
[0043] A method for manufacturing a transfer mask using the mask
blank according to any one of Configurations 1 to 6,
[0044] wherein the transfer mask has a first pattern including a
transfer pattern in the light-semitransmissive film, and has a
second pattern including a light shielding band pattern in the
etching mask film and the light shielding film, and
[0045] wherein the method includes:
[0046] forming the second pattern in the light shielding film by
dry etching with an oxygen-containing chlorine-based gas using a
first resist film having the second pattern formed on the light
shielding film as a mask;
[0047] forming the first pattern in the etching mask film by dry
etching with the oxygen-containing chlorine-based gas using a
second resist film having the first pattern formed on the etching
mask film and the light shielding film as a mask;
[0048] forming the first pattern in the light-semitransmissive film
by dry etching with a fluorine-based gas using the etching mask
film having the first pattern as a mask; and
[0049] forming the second pattern in the etching mask film by dry
etching with the oxygen-containing chlorine-based gas using a third
resist film having the second pattern formed on the light shielding
film as a mask.
(Configuration 15)
[0050] A method for manufacturing a transfer mask using the mask
blank according to any one of Configurations 7 to 11,
[0051] wherein the transfer mask has a third pattern including a
transfer pattern comprised of an etching pattern in the transparent
substrate, and has a fourth pattern including a light shielding
band pattern in the etching mask film and the light shielding film;
and
[0052] wherein the method includes:
[0053] forming the fourth pattern in the light shielding film by
dry etching with an oxygen-containing chlorine-based gas using a
fourth resist film having the fourth pattern formed on the light
shielding film as a mask;
[0054] forming the third pattern in the etching mask film by dry
etching with the oxygen-containing chlorine-based gas using as a
fifth resist film having the third pattern formed on the etching
mask film and the light shielding film a mask;
[0055] etching into a surface of the transparent substrate to form
the third pattern by dry etching with a fluorine-based gas using
the etching mask film having the third pattern as a mask; and
[0056] forming the fourth pattern in the etching mask film by dry
etching with the oxygen-containing chlorine-based gas using a sixth
resist film having the fourth pattern formed on the light shielding
film as a mask.
(Configuration 16)
[0057] A method for manufacturing a semiconductor device, including
the exposure process in which the transfer mask according to
Configuration 12 or 13 is used to transfer a transfer pattern of
the transfer mask onto a semiconductor substrate by a lithographic
method.
(Configuration 17)
[0058] A method for manufacturing a semiconductor device, including
the exposure process in which the transfer mask manufactured by the
method for manufacturing a transfer mask according to Configuration
14 or 15 is used to transfer a transfer pattern of the transfer
mask onto a semiconductor substrate by a lithographic method.
Effect of the Disclosure
[0059] According to the present disclosure, in a mask blank having
a structure in which a light-semitransmissive film, an etching mask
film, and a light shielding film are laminated in this order on a
transparent substrate, even if the light-semitransmissive film is
made of a material containing silicon and the light shielding film
is made of a material containing chromium, a fine transfer pattern
can be formed in the light-semitransmissive film with high
accuracy. Also, the mask blank of the present disclosure can be
used to manufacture a transfer mask having a pattern formed in the
light-semitransmissive film with high accuracy. Further, this
transfer mask can be used to manufacture a semiconductor device
having a fine pattern with high accuracy.
[0060] According to the present disclosure, in a mask blank having
a structure in which an etching mask film and a light shielding
film are laminated in this order on a transparent substrate, even
if the light shielding film is made of a material containing
chromium, a fine etching pattern can be formed in the transparent
substrate with high accuracy. Also, the mask blank of the present
disclosure can be used to manufacture a transfer mask having the
etching pattern formed in the transparent substrate with high
accuracy. Further, this transfer mask can be used to manufacture a
semiconductor device having a fine pattern with high accuracy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] FIG. 1 is a cross-sectional view showing a structure of a
mask blank according to Embodiment 1 of the present disclosure.
[0062] FIG. 2 is a cross-sectional view showing a structure of a
transfer mask according to Embodiment 1 of the present
disclosure.
[0063] FIGS. 3A to 3H are cross-sectional views showing a
manufacturing process of the transfer mask according to Embodiment
1 of the present disclosure.
[0064] FIG. 4 is a cross-sectional view showing a structure of a
mask blank according to Embodiment 2 of the present disclosure.
[0065] FIG. 5 is a cross-sectional view showing a structure of a
transfer mask according to Embodiment 2 of the present
disclosure.
[0066] FIGS. 6A to 6H are cross-sectional views showing a
manufacturing process of the transfer mask according to Embodiment
2 of the present disclosure.
DESCRIPTION OF EMBODIMENTS
[0067] Embodiment 1 of the present disclosure is described in
detail below. FIG. 1 is a cross-sectional view showing a structure
of a mask blank according to Embodiment 1 of the present
disclosure. The mask blank 100 of the present disclosure shown in
FIG. 1 has a structure in which a light-semitransmissive film 2, an
etching mask film 3, and a light shielding film 4 are laminated in
this order on a transparent substrate 1. FIG. 2 is a
cross-sectional view showing a structure of a transfer mask (phase
shift mask) according to Embodiment 1 of the present disclosure.
The transfer mask 200 of the present disclosure shown in FIG. 2 has
a structure in which a light-semitransmissive film
(light-semitransmissive pattern) 2a with a first pattern including
a transfer pattern 8 formed therein, an etching mask film (etching
mask pattern) 3b with a second pattern including a light shielding
band pattern formed therein, and a light shielding film (light
shielding pattern) 4b with the second pattern formed therein are
laminated in this order. The transfer mask 200 is comprised of the
transparent substrate 1, and a laminated structure of the
light-semitransmissive pattern 2a, the etching mask pattern 3b, and
the light shielding pattern 4b.
[0068] In the mask blank according to Embodiment 1 of the present
disclosure, the light-semitransmissive film 2 is made of a material
containing silicon, the etching mask film 3 is made of a material
containing chromium, and the light shielding film 4 is made of a
material containing chromium and oxygen. In particular, it is
featured in that a ratio of the etching rate of the light shielding
film to the etching rate of the etching mask film in the dry
etching using the oxygen-containing chlorine-based gas is not less
than 3 and not more than 12.
[0069] The light-semitransmissive film 2 made of the material
containing silicon needs to be patterned by the dry etching with a
fluorine-based gas. There are limited materials which provide
sufficient etching selectivity in relation to the material
containing silicon in the dry etching with the fluorine-based gas,
and the material containing chromium is superior in this regard.
Conventionally, the material containing chromium has been used for
the etching mask film 3, and the transition metal silicide-based
material has been used for the light shielding film 4. However,
this structure has the above described problems.
[0070] Thus, the inventors made a diligent study on a structure
which makes it possible to form the fine transfer pattern in the
light-semitransmissive film 2 with high accuracy even if the
material containing chromium is used for both the etching mask film
3 and the light shielding film 4. If the light shielding film 4 is
made of the material containing chromium, it is difficult to reduce
its thickness to a predetermined thickness or less due to a
restriction of optical density. In view of this, the inventors
reached the conclusion that the process of manufacturing a transfer
mask from a mask blank should not include performing the dry
etching on the light shielding film 4 with the oxygen-containing
chlorine-based gas using as a mask a resist film having a pattern
(first pattern) including a transfer pattern to be formed in the
light-semitransmissive film 2. Further, they conceived that
forming, in the light shielding film 4, a pattern (second pattern)
including a light shielding band pattern that is to be included in
the light shielding film 4 upon the completion of the transfer mask
is performed earlier in the process of manufacturing a transfer
mask from a mask blank. By doing so, a surface of the etching mask
film 3 is exposed in a transfer pattern forming region, so that the
etching mask film 3 can be subjected directly to the dry etching
with the oxygen-containing chlorine-based gas using as a mask the
resist film having the pattern (first pattern) including the
transfer pattern to be formed in the light-semitransmissive film
2.
[0071] On the one hand, it was found that in the dry etching with
the oxygen-containing chlorine-based gas for forming the second
pattern in the light shielding film 4, the etch selectivity between
the light shielding film 4 and the etching mask film 3 may be lower
than the etch selectivity between the conventional light shielding
film made of the transition metal silicide-based material and the
conventional etching mask film made of the chromium-based material
(etch selectivity such that the reduction amount of thickness of
the etching mask film due to the patterning of the light shielding
film by the dry etching is 1 nm or less). It was also found that if
the etching mask film 3 with the thickness of 2 nm or more remains
at the completion of the dry etching for forming the second pattern
in the light shielding film 4, the first pattern can be formed in
the etching mask film 3 with accuracy by the dry etching with the
oxygen-containing chlorine-based gas using as a mask the resist
film having the first pattern.
[0072] On the other hand, it was found that if the reduction amount
of thickness of the etching mask film due to the dry etching for
forming the second pattern in the light shielding film 4 is too
large (5 nm or more), it becomes difficult to form the first
pattern in the etching mask film 3 with accuracy. It appears that
the etching mask film only has to be formed to have the thickness
in view of the above reduction amount during the manufacture of the
mask blank. However, when forming the pattern in the thin film by
the dry etching, regions in the thin film where the surfaces are
exposed without the masking by the resist film, etc. are not
entirely removed at a time. Due to differences in conditions such
as a difference in density of the pattern or etching gas
distribution, the difference of the in-plane etching rate is
inevitably caused. It is difficult to avoid a time difference
between the region where the etching first reaches the lower end of
the thin film and the region where the etching last reaches the
lower end of the thin film, and the time difference tends to become
large if the regions to be removed by the etching are large.
[0073] In the region where the etching first reaches the lower end
of the light shielding film 4, the surface of the etching mask film
3 is continuously exposed to the etching gas until the etching
reaches the lower end of the light shielding film 4 throughout all
the regions to be removed. In the region where the etching last
reaches the lower end of the light shielding film 4, the surface of
the etching mask film 3 is hardly exposed to the etching gas. There
is a constant correlation between the duration of exposure of the
etching mask film 3 to the etching gas and the reduction amount of
thickness of the etching mask film 3. That is, if the reduction
amount of thickness of the etching mask film 3 due to the dry
etching for forming the second pattern in the light shielding film
4 is 5 nm, the difference in film thickness distribution in a plane
of the etching mask film 3 is estimated to be 5 nm, if simply
calculated. When the difference in film thickness distribution in
the etching mask film 3 is large during the dry etching for forming
in the etching mask film 3 the pattern (first pattern) including
the transfer pattern to be formed in the light-semitransmissive
film 2, the accuracy of the first pattern formed in the etching
mask film 3 is significantly deteriorated.
[0074] In view of the above technical problems, the inventors
concluded that the ratio of the etching rate of the light shielding
film 4 to the etching rate of the etching mask film 3 in the dry
etching with the oxygen-containing chlorine-based gas should be
such that the reduction amount of thickness of the etching mask
film 3 due to the dry etching for forming the second pattern in the
light shielding film 4 is less than 5 nm. In particular, the ratio
of the etching rate RA of the light shielding film 4 to the etching
rate RE of the etching mask film 3 in the dry etching with the
oxygen-containing chlorine-based gas (hereinafter referred to as
RA/RE ratio) should be 3 or more. The RA/RE ratio is preferably 3.2
or more, and more preferably 3.5 or more.
[0075] As described below, the chromium-based material containing
silicon causes the etching rate in the dry etching with the
oxygen-containing chlorine-based gas to be reduced in a significant
extent. When the etching rate in the dry etching of the etching
mask film 3 with the oxygen-containing chlorine-based gas is
reduced, the reduction amount of thickness of the etching mask film
3 due to the dry etching for forming the second pattern in the
light shielding film 4 is decreased. However, the dry etching with
the oxygen-containing chlorine-based gas using as a mask the resist
film having the pattern (first pattern) including the transfer
pattern to be formed in the light-semitransmissive film 2 should
form the pattern in the etching mask film 3 with high accuracy. As
the etching rate in the dry etching of the etching mask film 3 with
the oxygen-containing chlorine-based gas becomes slow, the resist
film having the first pattern needs to be thickened. If the
thickness of the resist film having the first pattern becomes 100
nm or more, the technical significance of provision of the etching
mask film 3 is diminished (the resist film with the thickness of 20
nm or more should remain after the completion of the patterning of
the etching mask film 3).
[0076] In view of the above, the inventors concluded that the RA/RE
ratio should be such that even if the thickness of the resist film
used in the dry etching for forming the first pattern in the
etching mask film 3 is less than 100 nm, the first pattern can be
formed in the etching mask film 3 with high accuracy. In
particular, the RA/RE ratio should be 12 or less. The RA/RE ratio
is preferably 10 or less, and more preferably 8 or less.
[0077] If the etching rate in the dry etching of the light
shielding film 4 with the oxygen-containing chlorine-based gas is
slow, it is difficult to achieve the above RA/RE ratio range. Thus,
the light shielding film 4 should be made of a material containing
at least chromium and oxygen. The oxygen content in the light
shielding film 4 is preferably 10 atom % or more, more preferably
15 atom % or more, and further preferably 20 atom % or more, in
order to enhance the RA/RE ratio.
[0078] The material containing chromium and oxygen tends to lower
the optical density per unit film thickness in relation to the
exposure light as the oxygen content increases. Since the light
shielding film 4 should ensure the predetermined optical density,
it is necessary to thicken the light shielding film 4 as the oxygen
content in the light shielding film 4 increases. When the light
shielding film 4 is thickened, the resist film having the second
pattern, which is used in the dry etching for forming the second
pattern in the light shielding film 4, should also be thickened. In
view of these points, the oxygen content in the light shielding
film 4 is preferably 40 atom % or less, more preferably 35 atom %
or less, and further preferably 30 atom % or less.
[0079] As described below, the chromium-based material containing
silicon causes the etching rate in the dry etching with the
oxygen-containing chlorine-based gas to be significantly reduced.
Thus, it is desirable that the material for forming the light
shielding film 4 does not substantially contain silicon. The phrase
"not substantially contain silicon" here means that the silicon
content in the light shielding film 4 is less than 1 atom %. The
silicon content in the light shielding film 4 is more preferably
not more than the detection lower limit. In the light shielding
film 4, the maximum peak of Si2p narrow spectrum obtained by X-ray
photoelectron spectroscopy analysis is further preferably not more
than the detection lower limit.
[0080] The light shielding film 4 may contain elements (such as
hydrogen, boron, indium, and tin) other than the above as long as
the etching rate in the dry etching with the oxygen-containing
chlorine-based gas does not significantly change. Further, the
light shielding film 4 may contain a noble gas element such as
helium, neon, argon, krypton, and xenon. The light shielding film 4
may contain carbon if its oxygen content is 10 atom % or more. This
is because the reduction in etching rate of the light shielding
film 4 due to the inclusion of carbon is less remarkable than the
reduction due to silicon. The preferable material for the light
shielding film 4 includes, for example, CrON, CrOC, and CrOCN.
[0081] When the light shielding film 4 is thickened, the resist
film having the second pattern (light shielding pattern), which is
used in the dry etching for forming the second pattern in the light
shielding film 4, should also be thickened. Thus, the thickness of
the light shielding film 4 is preferably 70 nm or less, more
preferably 60 nm or less, and further preferably 50 nm or less.
Also, the predetermined optical density is required for the light
shielding film 4. If the thinning of the light shielding film 4 is
attempted, the content of oxygen or nitrogen which triggers the
reduction in optical density of the material should be decreased.
When the content of oxygen or nitrogen in the light shielding film
4 is decreased, the etching rate in the dry etching of the light
shielding film 4 with the oxygen-containing chlorine-based gas is
also decreased. Thus, the thickness of the light shielding film 4
is preferably 20 nm or more, more preferably 25 nm or more, and
further preferably 30 nm or more.
[0082] On the other hand, even if the etching mask film 3 is made
of Cr metal alone without containing oxygen or nitrogen which is an
element triggering the increase of the etching rate in the dry
etching with the oxygen-containing chlorine-based gas, it is
difficult to achieve the RA/RE ratio of 3 or more. The
chromium-based material containing silicon can cause the etching
rate in the dry etching with the oxygen-containing chlorine-based
gas to be significantly reduced. The chromium-based material
containing carbon can also cause the etching rate in the dry
etching with the oxygen-containing chlorine-based gas to be
reduced, though not to the extent of reduction due to the silicon
inclusion. From these matters, the etching mask film 3 is
preferably made of a material which contains chromium and further
contains at least one or more elements selected from carbon and
silicon.
[0083] As mentioned above, the etching rate in the dry etching with
the oxygen-containing chlorine-based gas is significantly reduced
due to the inclusion of silicon in the etching mask film 3.
Further, as the etching rate in the dry etching of the etching mask
film with the oxygen-containing chlorine-based gas becomes slow,
the resist film having the first pattern (light-semitransmissive
pattern) should be thickened. In view of this, the silicon content
in the etching mask film 3 should be at least 10 atom % or less,
preferably 8 atom % or less, and more preferably 6 atom % or less.
In order to ensure the RA/RE ratio of 3 or more, the etching mask
film 3 desirably has the silicon content of 1 atom % or more. In
the etching mask film 3, the Si2p narrow spectrum obtained by X-ray
photoelectron spectroscopy analysis preferably has the maximum peak
at a binding energy of not less than 98 eV and not more than 101
eV.
[0084] The chromium-based material containing carbon causes the
etching rate in the dry etching with the oxygen-containing
chlorine-based gas to be reduced, though not to the extent of
reduction due to the silicon inclusion. The carbon content in the
etching mask film 3 should be at least 10 atom % or less,
preferably 9 atom % or less, and further preferably 8 atom % or
less. In order to ensure the RA/RE ratio of 3 or more, the etching
mask film 3 desirably has the carbon content of 1 atom % or more.
In the etching mask film 3, the C1s narrow spectrum obtained by
X-ray photoelectron spectroscopy analysis preferably has the
maximum peak at a binding energy of not less than 282 eV and not
more than 284 eV.
[0085] From the perspective of enhancement of the RA/RE ratio for
the light shielding film 4 and the etching mask film 3, it is
better not to contain elements (such as oxygen or nitrogen), which
increases the etching rate in the dry etching with the
oxygen-containing chlorine-based gas, in the material for forming
the etching mask film 3 as far as possible. The total content of
oxygen and nitrogen in the etching mask film 3 is preferably 5 atom
% or less, more preferably 3 atom % or less, and further preferably
1 atom % or less. In the etching mask film 3, the maximum peak of
O1s narrow spectrum obtained by X-ray photoelectron spectroscopy
analysis is preferably not more than the detection lower limit. In
the etching mask film 3, the maximum peak of N1s narrow spectrum
obtained by X-ray photoelectron spectroscopy analysis is also
preferably not more than the detection lower limit.
[0086] Given the decrease in oxygen content in the etching mask
film 3, it is preferable to contain carbon in the etching mask film
3 by adding a carbon-containing gas free of oxygen
(hydrocarbon-based gas, such as CH.sub.4, C.sub.2H.sub.6, or
C.sub.2H.sub.4) to a reactive gas in a film forming gas during the
formation of the etching mask film 3 by a sputtering method. The
etching mask film 3 may also be formed by the sputtering method
using a target containing chromium and carbon.
[0087] The etching mask film 3 may contain elements (such as
hydrogen or boron) other than the above as long as the etching rate
in the dry etching with the oxygen-containing chlorine-based gas
does not significantly change Further, the etching mask film 3 may
contain a noble gas element such as helium, neon, argon, krypton,
and xenon. The preferred material for the etching mask film 3
includes, for example, CrSi and CrC.
[0088] As described above, the reduction amount of thickness of the
etching mask film 3 due to the dry etching for forming the second
pattern in the light shielding film 4 should be less than 5 nm. The
etching mask film 3 after the thickness reduction by the dry
etching of the light shielding film 4 is provided with the first
pattern (light-semitransmissive pattern) formed therein by the dry
etching described in detail below. The etching mask film 3 with the
first pattern formed therein should function as an etching mask in
the dry etching for forming the first pattern in the
light-semitransmissive film 2. Also, there is an oft-requested
level for CD accuracy or accuracy in sidewall shape of the first
pattern formed in the etching mask film 3 that functions as a mask
in the dry etching for forming the first pattern in the
light-semitransmissive film 2. In order that the etching mask film
3 may sufficiently function as an etching mask, the remaining
thickness should be 2 nm or more.
[0089] In the electron beam drawing for forming the first pattern
in the resist film, the etching mask film 3 immediately thereunder
has sufficient conductivity, preferably. In order to ensure the
conductivity in the etching mask film 3, the remaining thickness
should be 2 nm or more. While depending on the material for forming
the etching mask film 3, the thickness of the etching mask film 3
is preferably 14 nm or less, and more preferably 12 nm or less.
Further, the thickness of the etching mask film 3 is preferably 3
nm or more, and more preferably 4 nm or more.
[0090] There is no particular limitation on the transparent
substrate 1, provided that it is transparent to the exposure light
wavelength used. In the present disclosure, a synthetic quartz
glass substrate, various other glass substrates (e.g., soda-lime
glass, aluminosilicate glass, etc.), and a calcium fluoride
substrate may be used. Refinement of a pattern for the
semiconductor device requires shortening of a wavelength of an
exposure light source used in photolithography during the
manufacture of the semiconductor device, in addition to the
refinement of a mask pattern formed in the light-semitransmissive
film 2. Nowadays, the exposure light sources used in the
manufacture of semiconductor devices are shifting from KrF excimer
lasers (wavelength: 248 nm) to ArF excimer lasers (wavelength: 193
nm), that is, shorter wavelength light sources are increasingly
used. Among the various glass substrates, the synthetic quartz
glass substrate has particularly high transparency at a wavelength
of the ArF excimer lasers or in a shorter wavelength range, and
thus, it is suitable as a substrate for the mask blank of the
present disclosure used in forming a high-definition transfer
pattern.
[0091] The light-semitransmissive film 2 is made of a material
which can be dry-etched with the etching gas containing the
fluorine-based gas. The light-semitransmissive film 2 has a
function to transmit the exposure light at the predetermined
transmittance. The transmittance of the light-semitransmissive film
2 with respect to the exposure light is preferably 1% or more. The
light-semitransmissive film 2 is preferably a phase shift film used
for a half tone phase shift mask, or a light-semitransmissive film
used for an enhancer-type phase shift mask.
[0092] The light-semitransmissive film (phase shift film) 2 of the
half tone phase shift mask blank transmits the light at an
intensity not substantially contributing to the light exposure
(e.g., 1% to 30% with respect to the exposure wavelength), and has
a predetermined phase difference (e.g., 150 degrees to 180
degrees). Thus, a phase of light transmitted through a
light-semitransmissive portion formed by patterning the
light-semitransmissive film 2 is in a substantially inverted
relation with respect to a phase of light transmitted through a
light-transmissive portion which transmits the light at an
intensity substantially contributing to the light exposure and has
no light-semitransmissive portion formed therein. In this way, the
two rays of light passed nearby a boundary between the
light-semitransmissive portion and the light-transmissive portion
enter the other's region due to a diffraction phenomenon, thereby
annihilating each other, so that a light intensity at the boundary
is nearly zero, and a contrast, i.e., a resolution, at the boundary
is improved.
[0093] While the light-semitransmissive film 2 of the mask blank
for the enhancer-type phase shift mask transmits the light at an
intensity not substantially contributing to the light exposure
(e.g., 1% to 30% with respect to the exposure wavelength), it has a
small phase difference caused in the transmitted exposure light
(e.g., the phase difference of 30 degrees or less, and preferably 0
degrees), which is different from the light-semitransmissive film 2
for the half tone phase shift mask blank.
[0094] While the light-semitransmissive film 2 can be made of the
material containing silicon, it is preferably made of a material
containing silicon and nitrogen. Further, the
light-semitransmissive film 2 is more preferably made of a material
containing silicon, a transition metal, and nitrogen. In this case,
the transition metal includes one or more metals of molybdenum
(Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr),
hafnium (Hf), nickel (Ni), vanadium (V), zirconium (Zr), ruthenium
(Ru), rhodium (Rh), niobium (Nb), palladium (Pd), etc., or alloys
of these metals. In addition to the above elements, the material of
the light-semitransmissive film 2 may contain elements such as
oxygen (O), carbon (C), hydrogen (H), and boron (B). The material
of the light-semitransmissive film 2 may also contain a noble gas
element such as helium (He), argon (Ar), krypton (Kr), and xenon
(Xe).
[0095] These materials have a high etching rate in the dry etching
with the etching gas containing the fluorine-based gas, and thus,
help to obtain various properties required for the
light-semitransmissive film 2. In particular, these materials are
desirable as materials for forming a phase shift film which should
strictly control the phase of the exposure light transmitted
through the light-semitransmissive film, or a
light-semitransmissive film for the enhancer-type phase shift mask
having the laminated structure of a phase delay film and a phase
progression film. When the light-semitransmissive film 2 is the
half tone phase shift film or a semitransparent laminated film, a
percentage [%] calculated by dividing the content [atom %] of
transition metal (M) by the total content [atom %] of transition
metal (M) and silicon (Si) in the film (M/(M+Si) ratio) is
preferably 35% or less, more preferably 25% or less, and further
preferably 20% or less. The transition metal is an element having a
higher extinction coefficient and a higher refractive index than
silicon. When a refractive index of a material for forming the
light-semitransmissive film 2 is too high, a phase change amount
due to a film thickness variation becomes large, and thus, it
becomes difficult to control both the phase and transmittance.
[0096] The light-semitransmissive film 2 can be made of a material
which contains a material containing silicon and nitrogen and
further contains one or more elements selected from metalloid
elements, non-metallic elements, and noble gases (hereinafter
collectively referred to as "silicon-based material"). The
light-semitransmissive film 2 made of the silicon-based material
does not contain transition metals which trigger the decrease in
light fastness against the ArF exposure light. Further, the
light-semitransmissive film 2 does not contain metallic elements
other than transition metals, since it is undeniable that they may
also trigger the decrease in light fastness against the ArF
exposure light. The light-semitransmissive film 2 made of the
silicon-based material may contain any of metalloid elements. It
preferably contains one or more elements selected from boron,
germanium, antimony, and tellurium among the metalloid elements,
since it can be expected to increase the conductivity of silicon
that is used as a target during the formation of the
light-semitransmissive film 2 by the sputtering method.
[0097] The light-semitransmissive film 2 made of the silicon-based
material may contain the noble gas element such as helium (He),
neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). The oxygen
content in the light-semitransmissive film 2 made of the
silicon-based material is preferably controlled to be 10 atom % or
less, and more preferably 5 atom % or less, and it is further
preferable that oxygen is not positively contained (the result of a
composition analysis through X-ray photoelectron spectroscopy is
not more than the detection lower limit). This is because the
silicon-based material containing oxygen tends to significantly
decrease the extinction coefficient k, which creates a need to
increase the entire thickness of the light-semitransmissive film 2.
The light-semitransmissive film 2 made of the silicon-based
material, except for the inevitably oxidized surface layer
(oxidized layer), can be configured as a single layer or as a
lamination layer comprised of a plurality of layers.
[0098] The light shielding film 4 can be a single layer structure,
or a laminated structure comprised of two or more layers. In the
transfer mask manufactured from the mask blank of the present
disclosure, the laminated structure of the light-semitransmissive
film 2, the etching mask film 3, and the light shielding film 4
forms a light shielding band. In the mask blank of the present
disclosure, the optical density (OD) with respect to the exposure
light in the laminated structure of the light-semitransmissive film
2, the etching mask film 3, and the light shielding film 4 should
be at least greater than 2.0, desirably 2.8 or more, and preferably
3.0 or more. Since the light-semitransmissive film 2 has the
predetermined transmittance with respect to the exposure light
depending on the intended use, the optical density of the etching
mask film 3 and the light shielding film 4 is to be adjusted.
[0099] While a method for forming the light-semitransmissive film
2, the etching mask film 3, and the light shielding film 4 on the
transparent substrate 1 preferably includes, for example, a
sputtering deposition method, it is not necessarily limited to the
sputtering deposition method in the present disclosure.
[0100] While the mask blank and the transfer mask of the present
disclosure are applicable to any exposure light, such as the ArF
excimer laser, KrF excimer laser, and i-line light, they are
preferably applied in particular to the photolithography using the
ArF excimer laser as the exposure light.
[0101] Embodiment 1 of the present disclosure also provides a
transfer mask in which a light-semitransmissive pattern is formed
in the light-semitransmissive film 2 of the mask blank according to
Embodiment 1 above and a light shielding pattern is formed in the
etching mask film 3 and the light shielding film 4; and a method
for manufacturing the transfer mask. FIGS. 3(A) to 3(H) are
cross-sectional views showing a manufacturing process of the
transfer mask according to Embodiment 1 of the present disclosure.
The method for manufacturing the transfer mask according to
Embodiment 1 is described below in accordance with the
manufacturing process shown in FIGS. 3(A) to 3(H). The detailed
structure of the mask blank 100 used here is as stated above.
[0102] First, a first resist film made of an organic material is
formed in contact with a surface of the light shielding film 4 of
the mask blank 100. Next, a second pattern including a desired
light shielding band pattern to be formed in the light shielding
film 4 is drawn on the resist film, and the development process is
conducted, thereby forming the first resist film (resist pattern)
5b having the second pattern including the desired light shielding
band pattern (see FIG. 3A).
[0103] Next, the dry etching is performed on the light shielding
film 4 with the oxygen-containing chlorine-based gas using the
resist pattern 5b as a mask to form the light shielding film (light
shielding pattern) 4b having the second pattern (see FIG. 3B). In
the dry etching of the light shielding film 4, the etching needs to
reach the lower end of the light shielding film 4 throughout all
the regions of the light shielding film 4 to be removed. Thus, when
the dry etching first reaches the lower end in a region of the
light shielding film 4, the dry etching should not be terminated,
rather the additional etching (overetching) should be performed so
as to remove all the regions of the light shielding film 4 to be
removed.
[0104] At this time, the etching mask film 3 is also etched to a
certain degree from its surface, but the etching mask film 3 which
remained after etching the light shielding film 4 has a thickness
of 2 nm or more. After that, the remaining resist pattern 5b is
removed. The chlorine-based gas in the oxygen-containing
chlorine-based gas used in the dry etching of the light shielding
film 4 may include, for example, Cl.sub.2, SiCl.sub.4, CHCl.sub.3,
CH.sub.2Cl.sub.2, CCl.sub.4, BCl.sub.3, and the like. The same
holds for the oxygen-containing chlorine-based gas used in the dry
etching of the etching mask film 3 described below.
[0105] Then, a second resist film made of an organic material is
formed in contact with surfaces of the etching mask film 3 and
light shielding pattern 4b. A first pattern including a desired
light-semitransmissive pattern (transfer pattern) to be formed in
the light-semitransmissive film 2 is drawn on the second resist
film, and the development process is conducted, thereby forming the
second resist film (resist pattern) 6a having the first pattern
including the desired light-semitransmissive pattern (see FIG.
3C).
[0106] Next, the dry etching is performed on the etching mask film
3 with the oxygen-containing chlorine-based gas using the resist
pattern 6a as a mask to form the etching mask film 3a having the
first pattern (see FIG. 3D). After that, the remaining resist
pattern 6a is removed.
[0107] The dry etching is then performed on the
light-semitransmissive film 2 with the fluorine-based gas using as
a mask the etching mask film 3a having the first pattern to form
the light-semitransmissive film (light-semitransmissive pattern) 2a
having the first pattern (see FIG. 3E). The fluorine-based gas used
in this dry etching includes an etching gas, such as SF.sub.6,
CHF.sub.3, CF.sub.4, C.sub.2F.sub.6, C.sub.4F.sub.8, and the like.
The fluorine-based gas in the present disclosure further includes a
mixed gas of the gas containing fluorine as listed above and a gas
such as helium or oxygen. The fluorine-based gas not containing
carbon (SF.sub.6) is preferable as an etching gas for etching the
light-semitransmissive film 2 since the etching selectivity between
the light-semitransmissive film 2 made of the material containing
silicon and the transparent substrate 1 is relatively easily
obtained.
[0108] Then, a third resist film (resist pattern) 7b made of an
organic material and having the second pattern is formed in contact
with the light shielding pattern 4b by a procedure similar to the
first resist film (see FIG. 3F).
[0109] The dry etching is performed on the etching mask film 3a
having the first pattern with the oxygen-containing chlorine-based
gas using the resist pattern 7b as a mask to form the etching mask
film 3b having the second pattern (see FIG. 3G). After that, the
remaining resist pattern 7b is removed, and the predetermined
cleaning is conducted, such that a transfer mask 200 is obtained
(see FIG. 3H).
[0110] As for the transfer mask 200, the dry etching is performed
directly on the etching mask film 3 using as a mask the second
resist film 6a having a pattern including the transfer pattern to
be formed in the light-semitransmissive film 2, and thus, the first
pattern including the transfer pattern shown as the etching mask
film 3a can be formed with high accuracy. Further, since the dry
etching is performed on the light-semitransmissive film 2 using as
a mask the etching mask film 3a having the first pattern including
the transfer pattern formed with high accuracy, the
light-semitransmissive pattern 2a can be formed in the
light-semitransmissive film 2 with high accuracy.
[0111] The present disclosure also provides a method for
manufacturing a semiconductor device using the transfer mask 200
according to Embodiment 1 above. The transfer mask 200 of the
present disclosure has the fine transfer pattern formed therein
with high accuracy. Therefore, when the transfer mask 200 is used
for the exposure transfer to the resist film on the semiconductor
device, a pattern can be formed in the resist film on the
semiconductor device with the accuracy that sufficiently satisfies
the design specification.
[0112] Embodiment 2 is described in detail below. FIG. 4 is a
cross-sectional view showing a structure of the mask blank
according to Embodiment 2 of the present disclosure. The mask blank
110 of the present disclosure shown in FIG. 4 has a structure in
which an etching mask film 13 and a light shielding film 14 are
laminated in this order on the transparent substrate 1. FIG. 5 is a
cross-sectional view showing a structure of a transfer mask
(chromeless phase shift mask) according to Embodiment 2 of the
present disclosure. The transfer mask 210 of the present disclosure
shown in FIG. 5 has in the transparent substrate 1 a third pattern
including an etching pattern (transfer pattern 18) etched to a
predetermined depth into the surface of the transparent substrate
1, and further has a structure in which the etching mask film
(etching mask pattern) 13b with a fourth pattern including a light
shielding band pattern formed therein and the light shielding film
(light shielding pattern) 14b with the fourth pattern formed
therein are laminated in this order on the transparent substrate
1.
[0113] The transfer mask 210 is configured to have a predetermined
phase difference (150 degrees to 190 degrees) between the exposure
light transmitted through an etched portion 1a of the transparent
substrate 1 where the etching pattern has been etched and the
exposure light transmitted through a non-etched portion where no
etching pattern is etched. The predetermined etching depth in the
etched portion 1a is set so as to obtain the above predetermined
phase difference. For example, for the transfer mask for which the
ArF excimer laser is used as the exposure light, the predetermined
etching depth is preferably between 144 nm and 183 nm.
[0114] The etching mask film 13 of Embodiment 2 is similar to the
etching mask film 3 of Embodiment 1 except for matters related to
the thickness. The light shielding film 14 of Embodiment 2 is
similar to the light shielding film 4 of Embodiment 1 except for
matters related to the optical density (OD) with respect to the
exposure light which is required for the laminated structure of the
light shielding film 14 and the etching mask film 13 and matters
related to the thickness of the light shielding film 14. The
transparent substrate 1 of Embodiment 2 is similar to the
transparent substrate 1 of Embodiment 1.
[0115] The etching mask film 13 needs to function as an etching
mask until the etched portion 1a having the above predetermined
etching depth is formed in the transparent substrate 1 by the dry
etching with the fluorine-based gas. Thus, after the fourth pattern
including the light shielding band pattern is formed in the light
shielding film 14 and before the dry etching for forming the etched
portion 1 a is performed, the remaining etching mask film 13 should
have the thickness of at least 4 nm or more. In view of these
points, while depending on the material for forming the etching
mask film 13, the thickness of the etching mask film 13 is
preferably 15 nm or less, and more preferably 13 nm or less.
Further, the thickness of the etching mask film 13 is preferably 5
nm or more, and more preferably 6 nm or more.
[0116] In Embodiment 2, when the transfer mask 210 is manufactured,
the light shielding band is formed by the laminated structure of
the light shielding film 14 and the etching mask film 13. Thus, the
optical density (OD) with respect to the exposure light in the
laminated structure of the light shielding film 14 and the etching
mask film 13 should be at least greater than 2.0, desirably 2.8 or
more, and preferably 3.0 or more. The optical density required for
the light shielding film 14 is higher than that of the light
shielding film 4 of Embodiment 1. Thus, the thickness of the light
shielding film 14 is preferably 80 nm or less, and more preferably
75 nm or less. Further, the thickness of the light shielding film
14 is preferably 40 nm or more, and more preferably 45 nm or
more.
[0117] Embodiment 2 of the present invention also provides a
transfer mask in which the third pattern including the transfer
pattern comprised of the etching pattern is formed in the
transparent substrate 1 of the mask blank according to Embodiment 2
above and the fourth pattern including the light shielding band
pattern is formed in the etching mask film 13 and the light
shielding film 14; and a method for manufacturing the transfer
mask. FIGS. 6(A) to 6(H) are cross-sectional views showing a
manufacturing process of the transfer mask according to Embodiment
2 of the present invention. The method for manufacturing the
transfer mask according to Embodiment 2 is described below in
accordance with the manufacturing process shown in FIGS. 6(A) to
6(H). The detailed structure of the mask blank 110 used here is as
stated above.
[0118] First, a fourth resist film made of an organic material is
formed in contact with a surface of the light shielding film 14 of
the mask blank 110. Next, the fourth pattern including the desired
light shielding band pattern to be formed in the light shielding
film 14 is drawn on the fourth resist film, and the development
process is conducted, thereby forming the fourth resist film
(resist pattern) 15b having the fourth pattern including the
desired light shielding band pattern (see FIG. 6A).
[0119] Next, the dry etching is performed on the light shielding
film 14 with the oxygen-containing chlorine-based gas using the
resist pattern 15b as a mask to form the light shielding film
(light shielding pattern) 14b having the fourth pattern (see FIG.
6B). In the dry etching of the light shielding film 14, the etching
needs to reach the lower end of the light shielding film 14
throughout all the regions of the light shielding film 14 to be
removed. Thus, when the dry etching first reaches the lower end in
a region of the light shielding film 14, the dry etching should not
be terminated, rather the additional etching (overetching) should
be performed so as to remove all the regions of the light shielding
film 14 to be removed.
[0120] At this time, the etching mask film 13 is also etched to a
certain degree from its surface, but the etching mask film 13 which
remained after etching the light shielding film 14 has a thickness
of 4 nm or more. After that, the remaining resist pattern 15b is
removed.
[0121] Then, a fifth resist film made of an organic material is
formed in contact with surfaces of the transparent substrate 1, the
etching mask film 13, and the light shielding film (light shielding
pattern) 14b having the fourth pattern. The third pattern including
a desired etching pattern (transfer pattern) to be formed in the
transparent substrate 1 is drawn on the fifth resist film, and the
development process is conducted, thereby forming the fifth resist
film (resist pattern) 16a having the third pattern including the
desired transfer pattern (see FIG. 6C).
[0122] Next, the dry etching is performed on the etching mask film
13 with the oxygen-containing chlorine-based gas using the resist
pattern 16a as a mask to form the etching mask film 13a having the
third pattern (see FIG. 6D). After that, the remaining resist
pattern 16a is removed.
[0123] The dry etching is then performed on the transparent
substrate 1 with the fluorine-based gas using as a mask the etching
mask film 13a having the third pattern to form in the transparent
substrate 1 the third pattern including the etching pattern
(transfer pattern 18) etched to a predetermined depth from the
surface of the transparent substrate 1 (see FIG. 6E).
[0124] Subsequently, a sixth resist film (resist pattern) 17b made
of an organic material and having the fourth pattern is formed in
contact with the light shielding film 14b by a procedure similar to
the fourth resist film (see FIG. 6F).
[0125] The dry etching is performed on the etching mask film 13a
with the oxygen-containing chlorine-based gas using the resist
pattern 17b as a mask to form the etching mask film 13b having the
fourth pattern (see FIG. 6G). After that, the remaining resist
pattern 17b is removed, and the predetermined cleaning is
conducted, such that a transfer mask 210 is obtained (see FIG.
6H).
[0126] The oxygen-containing chlorine-based gas used in the dry
etching of the light shielding film 14 and the etching mask film 13
is similar to the one used in the method for manufacturing a
transfer mask of Embodiment 1. Further, as the fluorine-based gas
used in the dry etching in the method for manufacturing a transfer
mask of Embodiment 2, the fluorine-based gas containing carbon
(CF.sub.4, CHF.sub.3, C.sub.2F.sub.6, C.sub.4F.sub.8, and the like)
is applied. The gas made by mixing the gas such as helium or oxygen
with this fluorine-based gas is also applicable.
[0127] As for the transfer mask 210, the dry etching is performed
directly on the etching mask film 13 using as a mask the fifth
resist film having the third pattern including the desired etching
pattern (transfer pattern 18) to be formed in the transparent
substrate 1, and thus, the third pattern including the transfer
pattern can be formed in the etching mask film 13 with high
accuracy. Moreover, the dry etching is performed on the transparent
substrate 1 using as a mask the etching mask film 13a having the
third pattern including the transfer pattern formed with high
accuracy, and thus, the etching pattern (transfer pattern 18) can
be formed in the transparent substrate 1 with high accuracy.
[0128] The present invention also provides a method for
manufacturing a semiconductor device using the transfer mask 210
according to Embodiment 2 above. The transfer mask 210 of the
present invention has the fine transfer pattern formed with high
accuracy. Therefore, when the transfer mask 210 is used for the
exposure transfer to the resist film on the semiconductor device, a
pattern can be formed in the resist film on the semiconductor
device with the accuracy that sufficiently satisfies the design
specification.
[0129] As an alternative embodiment of the mask blank 110 according
to Embodiment 2 above, there is a mask blank which includes an
etching stopper film and a phase shift film between the transparent
substrate 1 and the etching mask film 13. The phase shift film of
the mask blank of the alternative embodiment is made of a material
which contains silicon and oxygen and is transparent to the
exposure light. Further, the phase shift film has a function to
transmit the exposure light at a transmittance of 95% or more
(preferably 96% or more, and more preferably 97% or more), and a
function to generate a phase difference of not less than 150
degrees and not more than 190 degrees between the exposure light
transmitted through the phase shift film and the exposure light
transmitted through the air for the same distance as the thickness
of the phase shift film.
[0130] The etching stopper film of the alternative embodiment is
made of a material which has sufficient etching selectivity in
relation to the above-described phase shift film in the dry etching
with the fluorine-based gas for forming the transfer pattern in the
phase shift film. This etching stopper film preferably has a high
transmittance with respect to the exposure light, and high etching
selectivity in relation to the phase shift film. The material for
forming the etching stopper film includes a material containing
aluminum and oxygen, a material containing aluminum, silicon, and
oxygen, a material containing hafnium and oxygen, and the like. The
other matters related to the transparent substrate, the etching
mask film, and the light shielding film are similar to those of the
mask blank according to Embodiment 2 above.
[0131] The mask blank of the alternative embodiment has a structure
in which the etching stopper film, the phase shift film, the
etching mask film, and the light shielding film are laminated in
this order on the transparent substrate. It is featured in that the
phase shift film is made of the material containing silicon and
oxygen; the etching stopper film is made of the material which has
etching selectivity in relation to the phase shift film when
forming the transfer pattern in the phase shift film by the dry
etching using the fluorine-based gas; the etching mask film is made
of the material containing chromium; the light shielding film is
made of the material containing chromium and oxygen; and a ratio of
the etching rate of the light shielding film to the etching rate of
the etching mask film in the dry etching using the
oxygen-containing chlorine-based gas is not less than 3 and not
more than 12.
[0132] When a transfer mask is manufactured from the mask blank of
the alternative embodiment, the fine transfer pattern is formed in
the phase shift film. Since the etching stopper film is provided
between the phase shift film and the transparent substrate, such a
transfer mask is superior in phase controllability to the transfer
mask 210 of Embodiment 2 which has the transfer pattern 18 formed
therein by etching away the transparent substrate 1.
[0133] The transfer mask of the alternative embodiment is featured
in that a fifth pattern including the transfer pattern is formed in
the phase shift film of the above mask blank of the alternative
embodiment and a sixth pattern including the light shielding band
pattern is formed in the etching mask film and the light shielding
film.
[0134] Further, a method for manufacturing the transfer mask of the
alternative embodiment uses the above mask blank of the alternative
embodiment. The transfer mask has the fifth pattern including the
transfer pattern in the phase shift film and the sixth pattern
including the light shielding band pattern in the etching mask film
and the light shielding film. It is featured in that the method
includes: performing the dry etching with the oxygen-containing
chlorine-based gas using as a mask a seventh resist film having the
sixth pattern formed on the light shielding film, thereby forming
the sixth pattern in the light shielding film; performing the dry
etching with the oxygen-containing chlorine-based gas using as a
mask an eighth resist film having the fifth pattern formed on the
etching mask film and the light shielding film, thereby forming the
fifth pattern in the etching mask film; performing the dry etching
with the fluorine-based gas using as a mask the etching mask film
having the fifth pattern, thereby forming the fifth pattern in the
phase shift film; and performing the dry etching with the
oxygen-containing chlorine-based gas using as a mask a ninth resist
film having the sixth pattern formed on the light shielding film,
thereby forming the sixth pattern in the etching mask film.
EXAMPLES
[0135] Embodiments of the present invention are described more
specifically below based on examples.
Example 1
[0136] The transparent substrate 1 was prepared, which had a main
surface dimension of about 152 mm.times.about 152 mm and a
thickness of about 6.35 mm, and was made of synthetic quartz glass.
The transparent substrate 1 had been polished to have predetermined
surface roughness (root mean square roughness Rq of 0.2 nm or less)
in its end faces and main surfaces, and subjected to predetermined
cleaning and drying processes.
[0137] Next, the transparent substrate 1 was placed in a
single-wafer DC sputtering apparatus, a mixed target of molybdenum
(Mo) and silicon (Si) (Mo:Si=12 atom %: 88 atom %) was used, and
the reactive sputtering (DC sputtering) in a mixed gas atmosphere
of argon (Ar), nitrogen (N.sub.2), and helium (He) was conducted,
such that the light-semitransmissive film 2 made of molybdenum,
silicon, and nitrogen (MoSiN film: Mo: 12 atom %, Si: 39 atom %, N:
49 atom %) and having a thickness of 69 nm was formed on the
transparent substrate 1. The composition of the MoSiN film was
obtained as a result from Auger electron spectroscopy (AES).
[0138] Then, the transparent substrate 1 with the above MoSiN film
(light-semitransmissive film 2) formed thereon was subjected to a
treatment for forming an oxidized layer in a surface layer of the
light-semitransmissive film 2. In particular, a heating furnace
(electric furnace) was used to conduct the heat treatment at a
heating temperature of 450.degree. C. in the air for one hour. The
light-semitransmissive film 2 after the heat treatment was analyzed
by Auger electron spectroscopy (AES). As a result, formation of the
oxidized layer having a thickness of about 1.5 nm measured from the
surface of the light-semitransmissive film 2 was confirmed, and the
oxygen content in the oxidized layer was 42 atom %. For the MoSiN
film (light-semitransmissive film 2) after the heat treatment, the
transmittance and phase difference at a wavelength of the ArF
excimer laser light (about 193 nm) were measured by a phase shift
amount measurement apparatus. As a result, the transmittance was
6.07%, and the phase difference was 177.3 degrees.
[0139] Then, the transparent substrate 1 was placed in the
single-wafer DC sputtering apparatus, a chromium (Cr) target was
used, and the reactive sputtering (DC sputtering) in a mixed gas
atmosphere of argon (Ar) and methane (CH.sub.4) was conducted, such
that the etching mask film 3 made of chromium and carbon (CrC film:
Cr: 95 atom %, C: 5 atom %) and having a thickness of 6 nm was
formed in contact with the surface of the light-semitransmissive
film 2. The each film composition in the etching mask film 3 and
the light shielding film 4 described below was obtained by electron
spectroscopy for chemical analysis (ESCA: with RBS correction).
[0140] In this etching mask film 3, the C1s narrow spectrum
obtained by X-ray photoelectron spectroscopy analysis had the
maximum peak at a binding energy of not less than 282 eV and not
more than 284 eV. Further, in this etching mask film 3, the
respective maximum peaks of O1s and N1s narrow spectra obtained by
X-ray photoelectron spectroscopy analysis were not more than the
detection lower limit.
[0141] Then, the transparent substrate 1 was placed in the
single-wafer DC sputtering apparatus, a chromium (Cr) target was
used, and the reactive sputtering (DC sputtering) in a mixed gas
atmosphere of argon (Ar), carbon dioxide (CO.sub.2), and helium
(He) was performed, such that the light shielding film 4 made of
chromium, oxygen, and carbon (CrOC film: Cr: 56 atom %, O: 29 atom
%, C: 15 atom %) and having a thickness of 43 nm was formed in
contact with the surface of the etching mask film 3. The
predetermined cleaning process was further conducted, such that the
mask blank 100 of Example 1 was obtained.
[Manufacture of Transfer Mask]
[0142] Next, the mask blank 100 of Example 1 was used to
manufacture the transfer mask 200 of Example 1 through the
following procedure. First, the first resist film made of a
chemically amplified resist for electron beam drawing and having a
thickness of 100 nm was formed in contact with the surface of the
light shielding film 4 by a spin coating method. Then, a second
pattern including a light shielding band pattern was drawn on the
first resist film with electron beams, and the predetermined
development and cleaning processes were conducted, such that a
first resist film (resist pattern) 5b having the second pattern was
formed (see FIG. 3A).
[0143] Subsequently, the dry etching was performed on the light
shielding film 4 with the oxygen-containing chlorine-based gas (gas
flow ratio of Cl.sub.2:O.sub.2=4:1) using the resist pattern 5b as
a mask, such that the light shielding film (light shielding
pattern) 4b having the second pattern was formed (see FIG. 3B). The
duration of the dry etching of the light shielding film 4
corresponded to the amount of time from the beginning of the dry
etching to first arrival at the lower end in a region of the light
shielding film 4 (just etching time) plus 30% of the just etching
time. After that, the resist pattern 5b was removed. At this point,
the etching mask film 3 in the regions where the light shielding
film 4 was removed was also etched from its surface.
[0144] The etching mask film 3 which remained after etching the
light shielding film 4 could have the thickness of 2.6 nm in the
thinnest region in a plane (the most etched region). The difference
in film thickness distribution in a plane of the etching mask film
3 was 3.4 nm at most, which was within the range below 5 nm. The
ratio of the etching rate of the light shielding film 4 to the
etching rate of the etching mask film 3 in the dry etching using
the oxygen-containing chlorine-based gas was 3.6, which was within
the range of not less than 3 and not more than 12.
[0145] Then, the second resist film made of the chemically
amplified resist for electron beam drawing and having a thickness
of 80 nm was formed in contact with the surfaces of the etching
mask film 3 and the light shielding film 4b by the spin coating
method. Then, a first pattern including a light-semitransmissive
pattern (transfer pattern) to be formed in the
light-semitransmissive film 2 was drawn on the second resist film
with electron beams, and the predetermined development and cleaning
processes were conducted, such that the second resist film (resist
pattern) 6a having the first pattern was formed (see FIG. 3C). The
first pattern included, in a transfer pattern forming region (inner
region of 132 mm.times.104 mm), a transfer pattern of DRAM hp32 nm
generation (a fine pattern including SRAF with a line width of 40
nm) to be formed in the light-semitransmissive film 2.
[0146] Next, the dry etching was performed on the etching mask film
3 with the oxygen-containing chlorine-based gas (gas flow ratio of
Cl.sub.2:O.sub.2=4:1) using the resist pattern 6a as a mask, such
that the etching mask film 3a having the first pattern was formed
(see FIG. 3D). The thickness of the resist pattern 6a which
remained after forming the etching mask film 3a was 31 nm, that is,
the resist pattern 6a having the thickness of 20 nm or more could
remain. After that, the resist pattern 6a was removed.
[0147] Then, the dry etching was performed with the etching gas
containing the fluorine-based gas (SF.sub.6+He) using as a mask the
etching mask film 3a having the first pattern, such that the
light-semitransmissive film (light-semitransmissive pattern) 2a
having the first pattern was formed (see FIG. 3E).
[0148] Next, the third resist film made of the chemically amplified
resist for electron beam drawing and having a thickness of 80 nm
was formed in contact with the surfaces of the transparent
substrate 1, the light-semitransmissive film 2a, the etching mask
film 3a, and the light shielding film 4b by the spin coating
method. Then, the second pattern including the light shielding band
pattern was drawn on the third resist film with electron beams, and
the predetermined development and cleaning processes were
conducted, such that the third resist film (resist pattern) 7b
having the second pattern was formed (see FIG. 3F).
[0149] Next, the dry etching was performed on the etching mask film
3a with the oxygen-containing chlorine-based gas (gas flow ratio of
Cl.sub.2:O.sub.2=4:1) using the resist pattern 7b as a mask, such
that the etching mask film 3b having the second pattern was formed
(see FIG. 3G). After that, the remaining resist pattern 7b was
removed, and the predetermined cleaning was conducted, such that
the transfer mask 200 was obtained (see FIG. 3H).
[Evaluation of Pattern Transfer Performance]
[0150] Using AIMS193 (manufactured by Carl Zeiss), a simulation of
a transfer image upon the exposure transfer to the resist film on
the semiconductor device with the exposure light at a wavelength of
193 nm was performed on the manufactured transfer mask 200 of
Example 1. As a result of inspection of the image transferred by
exposure in this simulation, there was no short-circuit or
disconnection found in patterns, which satisfied the design
specification sufficiently. It can be considered from this result
that the circuit pattern finally formed on the semiconductor device
may have great accuracy, even if the transfer mask of Example 1 is
set on a mask stage of the exposure apparatus to perform the
exposure transfer to the resist film on the semiconductor
device.
Example 2
[0151] The mask blank 100 of Example 2 was manufactured by a
procedure similar to Example 1 except that the etching mask film 3
was made of CrSi. In particular, the transparent substrate 1 was
placed in the single-wafer DC sputtering apparatus, a mixed target
of chromium (Cr) and silicon (Si) (Cr:Si=97 atom %: 3 atom %) was
used, and the sputtering (DC sputtering) in an argon (Ar) gas
atmosphere was performed, such that the etching mask film 3 made of
chromium and silicon (CrSi film) and having a thickness of 4 nm was
formed in contact with the surface of the light-semitransmissive
film 2.
[0152] In the etching mask film 3, the Si2p narrow spectrum
obtained by X-ray photoelectron spectroscopy analysis had the
maximum peak at the binding energy of not less than 98 eV and not
more than 101 eV. Further, in the etching mask film 3, the
respective maximum peaks of O1s and N1s narrow spectra obtained by
X-ray photoelectron spectroscopy analysis were not more than the
detection lower limit.
[Manufacture of Transfer Mask]
[0153] Then, the mask blank 100 of Example 2 was used to
manufacture the transfer mask 200 of Example 2 by a procedure
similar to Example 1. Also in the manufacture of the transfer mask
200 in Example 2, the dry etching was performed on the light
shielding film 4 with the oxygen-containing chlorine-based gas (gas
flow ratio of Cl.sub.2:O.sub.2=4:1) using the resist pattern 5b as
a mask, such that the light shielding film (light shielding
pattern) 4b having the second pattern was formed.
[0154] By this process, the etching mask film 3 in the regions
where the light shielding film 4 was removed was etched from its
surface. The etching mask film 3 of Example 2 which remained after
etching the light shielding film 4 could have the thickness of 2.0
nm in the thinnest region in a plane (the most etched region). The
difference in film thickness distribution in a plane of the etching
mask film 3 was 2.0 nm at most, which was within the range below 5
nm. The ratio of the etching rate of the light shielding film 4 to
the etching rate of the etching mask film 3 in the dry etching
using the oxygen-containing chlorine-based gas was 6.5, which was
within the range of not less than 3 and not more than 12.
[0155] Also in the manufacture of the transfer mask 200 of Example
2, the dry etching was performed on the etching mask film 3 with
the oxygen-containing chlorine-based gas (gas flow ratio of
Cl.sub.2:O.sub.2=4:1) using the resist pattern 6a as a mask, such
that the etching mask film 3a having the first pattern was formed.
At this time, the thickness of the resist pattern 6a which remained
after forming the etching mask film 3a was 24 nm, that is, the
resist pattern 6a having the thickness of 20 nm or more could
remain.
[Evaluation of Pattern Transfer Performance]
[0156] Using AIMS193 (manufactured by Carl Zeiss), a simulation of
a transfer image upon the exposure transfer to the resist film on
the semiconductor device with the exposure light at a wavelength of
193 nm was performed on the manufactured transfer mask 200 of
Example 2. As a result of inspection of the image transferred by
exposure in this simulation, there was no short-circuit or
disconnection found in patterns, which satisfied the design
specification sufficiently. It can be considered from this result
that the circuit pattern finally formed on the semiconductor device
may have great accuracy, even if the transfer mask of Example 2 is
set on the mask stage of the exposure apparatus to perform the
exposure transfer to the resist film on the semiconductor
device.
Example 3
[0157] The transparent substrate 1 was prepared in a manner similar
to Example 1. Then, the transparent substrate 1 was placed in the
single-wafer DC sputtering apparatus, a chromium (Cr) target was
used, and the reactive sputtering (DC sputtering) in the mixed gas
atmosphere of argon (Ar) and methane (CH.sub.4) was performed, such
that the etching mask film 13 made of chromium and carbon (CrC
film: Cr: 95 atom %, C: 5 atom %) and having a thickness of 8 nm
was formed in contact with the surface of the transparent substrate
1. The each film composition in the etching mask film 13 and the
light shielding film 14 described below was obtained by electron
spectroscopy for chemical analysis (ESCA: with RBS correction).
[0158] In the etching mask film 13, the C1s narrow spectrum
obtained by the X-ray photoelectron spectroscopy analysis had the
maximum peak at the binding energy of not less than 282 eV and not
more than 284 eV. Further, in this etching mask film 13, the
respective maximum peaks of O1s and N1s narrow spectra obtained by
X-ray photoelectron spectroscopy analysis were not more than the
detection lower limit.
[0159] Then, the transparent substrate 1 was placed in the
single-wafer DC sputtering apparatus, a chromium (Cr) target was
used, and the reactive sputtering (DC sputtering) in the mixed gas
atmosphere of argon (Ar), carbon dioxide (CO.sub.2), and helium
(He) was performed, such that the light shielding film 14 made of
chromium, oxygen, and carbon (CrOC film: Cr: 56 atom %, O: 29 atom
%, C: 15 atom %) and having a thickness of 71 nm was formed in
contact with the surface of the etching mask film 13. The
predetermined cleaning process was further conducted, such that the
mask blank 110 of Example 3 was obtained.
[Manufacture of Transfer Mask]
[0160] Next, the mask blank 110 of Example 3 was used to
manufacture the transfer mask 210 of Example 3 through the
following procedure. First, the fourth resist film made of a
chemically amplified resist for electron beam drawing and having a
thickness of 100 nm was formed in contact with the surface of the
light shielding film 14 by the spin coating method. Then, a fourth
pattern including the light shielding band pattern was drawn on the
fourth resist film with electron beams, and the predetermined
development and cleaning processes were conducted, such that the
fourth resist film (resist pattern) 15b having the fourth pattern
was formed (see FIG. 6A).
[0161] Subsequently, the dry etching was performed on the light
shielding film 14 with the oxygen-containing chlorine-based gas
(gas flow ratio of Cl.sub.2:O.sub.2=4:1) using the resist pattern
15b as a mask, such that the light shielding film (light shielding
pattern) 14b having the fourth pattern was formed (see FIG. 6B).
The duration of the dry etching of the light shielding film 14
corresponded to the amount of time from the beginning of the dry
etching to first arrival at the lower end in a region of the light
shielding film 14 (just etching time) plus 20% of the just etching
time. After that, the resist pattern 15b was removed. At this
point, the etching mask film 13 in the regions where the light
shielding film 14 was removed was also etched from its surface.
[0162] The etching mask film 13 which remained after etching the
light shielding film 14 could have the thickness of 4.0 nm in the
thinnest region in a plane (the most etched region). The difference
in film thickness distribution in a plane of the etching mask film
13 was 4.0 nm at most, which was within the range below 5 nm. The
ratio of the etching rate of the light shielding film 14 to the
etching rate of the etching mask film 13 in the dry etching using
the oxygen-containing chlorine-based gas was 3.6, which was within
the range of not less than 3 and not more than 12.
[0163] Then, a fifth resist film made of the chemically amplified
resist for electron beam drawing and having a thickness of 80 nm
was formed in contact with the surfaces of the etching mask film 13
and the light shielding film 14b by the spin coating method. Then,
a third pattern including the etching pattern (transfer pattern) to
be formed in the transparent substrate 1 was drawn on the fifth
resist film with electron beams, and the predetermined development
and cleaning processes were conducted, such that the fifth resist
film (resist pattern) 16a having the third pattern was formed (see
FIG. 6C). The third pattern included, in a transfer pattern forming
region (inner region of 132 mm.times.104 mm), a transfer pattern of
DRAM hp22 nm generation to be formed in the transparent
substrate.
[0164] Next, the dry etching was performed on the etching mask film
13 with the oxygen-containing chlorine-based gas (gas flow ratio of
Cl.sub.2:O.sub.2=4:1) using the resist pattern 16a as a mask, such
that the etching mask film 13a having the third pattern was formed
(see FIG. 6D). The thickness of the resist pattern 16a which
remained after forming the etching mask film 13a was 27 nm, that
is, the resist pattern 16a having the thickness of 20 nm or more
could remain. After that, the resist pattern 16a was removed.
[0165] Then, the dry etching was performed with the etching gas
containing the fluorine-based gas (CF.sub.4+He) using as a mask the
etching mask film 13a having the third pattern, so that the third
pattern including the etching pattern (transfer pattern 18) that
was etched to a depth of 173 nm from the surface of the transparent
substrate 1 was formed in the transparent substrate 1 (see FIG.
6E).
[0166] Then, a sixth resist film made of the chemically amplified
resist for electron beam drawing and having a thickness of 80 nm
was formed in contact with the surfaces of the transparent
substrate 1, the etching mask film 13a, and the light shielding
film 14b by the spin coating method. Then, the fourth pattern
including the light shielding band pattern was drawn on the sixth
resist film with electron beams, and the predetermined development
and cleaning processes were conducted, such that the sixth resist
film (resist pattern) 17b having the fourth pattern was formed (see
FIG. 6F).
[0167] Next, the dry etching was performed on the etching mask film
13a with the oxygen-containing chlorine-based gas (gas flow ratio
of Cl.sub.2:O.sub.2=4:1) using the resist pattern 17b as a mask,
such that the etching mask film 13b having the fourth pattern was
formed (see FIG. 6G). After that, the remaining resist pattern 17b
was removed, and the predetermined cleaning was conducted, such
that the transfer mask 210 was obtained (see FIG. 6H).
[Evaluation of Pattern Transfer Performance]
[0168] Using AIMS193 (manufactured by Carl Zeiss), a simulation of
a transfer image upon the exposure transfer to the resist film on
the semiconductor device with the exposure light at a wavelength of
193 nm was performed on the manufactured transfer mask 210 of
Example 3. As a result of inspection of the image transferred by
exposure in this simulation, there was no short-circuit or
disconnection found in patterns, which satisfied the design
specification sufficiently. It can be considered from this result
that the circuit pattern finally formed on the semiconductor device
may have great accuracy, even if the transfer mask of Example 3 is
set on the mask stage of the exposure apparatus to perform the
exposure transfer to the resist film on the semiconductor
device.
Example 4
[0169] The mask blank 110 of Example 4 was manufactured by a
procedure similar to Example 3 except that the etching mask film 13
was made of CrSi. In particular, the transparent substrate 1 was
placed in the single-wafer DC sputtering apparatus, a mixed target
of chromium (Cr) and silicon (Si) (Cr:Si=97 atom %: 3 atom %) was
used, and the sputtering (DC sputtering) in the argon (Ar) gas
atmosphere was performed, such that the etching mask film 13 made
of chromium and silicon (CrSi film) and having a thickness of 7 nm
was formed in contact with the surface of the transparent substrate
1.
[0170] In the etching mask film 13, the Si2p narrow spectrum
obtained by X-ray photoelectron spectroscopy analysis had the
maximum peak at the binding energy of not less than 98 eV and not
more than 101 eV. Further, in the etching mask film 13, the
respective maximum peaks of O1s and N1s narrow spectra obtained by
X-ray photoelectron spectroscopy analysis were not more than the
detection lower limit.
[Manufacture of Transfer Mask]
[0171] The mask blank 110 of Example 4 was used to manufacture the
transfer mask 210 of Example 4 by a procedure similar to Example 3.
Also in the manufacture of the transfer mask 210 of Example 4, the
dry etching was performed on the light shielding film 14 with the
oxygen-containing chlorine-based gas (gas flow ratio of
Cl.sub.2:O.sub.2=4:1) using the resist pattern 15b as a mask, such
that the light shielding film (light shielding pattern) 14b having
the fourth pattern was formed.
[0172] By this process, the etching mask film 13 in the regions
where the light shielding film 14 was removed was etched from its
surface. The etching mask film 13 of Example 4 which remained after
etching the light shielding film 14 could have the thickness of 4.8
nm in the thinnest region in a plane (the most etched region). The
difference in film thickness distribution in a plane of the etching
mask film 13 was 2.2 nm at most, which was within the range below 5
nm. The ratio of the etching rate of the light shielding film 14 to
the etching rate of the etching mask film 13 in the dry etching
using the oxygen-containing chlorine-based gas was 6.5, which was
within the range of not less than 3 and not more than 12.
[0173] Also in the manufacture of the transfer mask 210 of Example
4, the dry etching was performed on the etching mask film 13 with
the oxygen-containing chlorine-based gas (gas flow ratio of
Cl.sub.2:O.sub.2=4:1) using the resist pattern 16a as a mask, such
that the etching mask film 13a having the first pattern was formed.
At this time, the thickness of the resist pattern 16a which
remained after forming the etching mask film 13a was 23 nm, that
is, the resist pattern 16a having the thickness of 20 nm or more
could remain.
[Evaluation of Pattern Transfer Performance]
[0174] Using AIMS193 (manufactured by Carl Zeiss), a simulation of
a transfer image upon the exposure transfer to the resist film on
the semiconductor device with the qexposure light at a wavelength
of 193 nm was performed on the manufactured transfer mask 210 of
Example 4. As a result of inspection of the image transferred by
exposure in this simulation, there was no short-circuit or
disconnection found in patterns, which satisfied the design
specification sufficiently. It can be considered from this result
that the circuit pattern finally formed on the semiconductor device
may have great accuracy, even if the transfer mask of Example 4 is
set on the mask stage of the exposure apparatus to perform the
exposure transfer to the resist film on the semiconductor
device.
Comparative Example 1
[0175] The mask blank 100 of Comparative Example 1 was manufactured
by a procedure similar to Example 1 except that the etching mask
film 3 was made of Cr metal. In particular, the transparent
substrate 1 was placed in the single-wafer DC sputtering apparatus,
the chromium (Cr) target was used, and the sputtering (DC
sputtering) in the argon (Ar) gas atmosphere was performed, such
that the etching mask film 3 made of chromium (Cr film) and having
a thickness of 8 nm was formed in contact with the surface of the
light-semitransmissive film 2.
[Manufacture of Transfer Mask]
[0176] Then, the mask blank 100 of Comparative Example 1 was used
to manufacture the transfer mask 200 of Comparative Example 1 by a
procedure similar to Example 1. Also in the manufacture of the
transfer mask 200 of Comparative Example 1, the dry etching was
performed on the light shielding film 4 with the oxygen-containing
chlorine-based gas (gas flow ratio of Cl.sub.2:O.sub.2=4:1) using
the resist pattern 5b as a mask, such that the light shielding film
(light shielding pattern) 4b having the second pattern was formed.
By this process, the etching mask film 3 in the regions where the
light shielding film 4 was removed was etched from its surface. The
etching mask film 3 of Comparative Example 1 which remained after
etching the light shielding film 4 could have the thickness of 2.8
nm in the thinnest region in a plane (the most etched region).
However, the difference in film thickness distribution in a plane
of the etching mask film 3 was 5.2 nm at most, i.e., not less than
5 nm.
[0177] The ratio of the etching rate of the light shielding film 4
to the etching rate of the etching mask film 3 in the dry etching
using the oxygen-containing chlorine-based gas was 2.5, which did
not fall within the range of not less than 3 and not more than
12.
[0178] Also in the manufacture of the transfer mask 200 of
Comparative Example 1, the dry etching was performed on the etching
mask film 3 with the oxygen-containing chlorine-based gas (gas flow
ratio of Cl.sub.2:O.sub.2=4:1) using the resist pattern 6a as a
mask, such that the etching mask film 3a having the first pattern
was formed. At this time, the thickness of the resist pattern 6a
which remained after forming the etching mask film 3a was 40 nm,
that is, the resist pattern 6a having the thickness of 20 nm or
more could remain.
[Evaluation of Pattern Transfer Performance]
[0179] Using AIMS193 (manufactured by Carl Zeiss), a simulation of
a transfer image upon the exposure transfer to the resist film on
the semiconductor device with the exposure light at a wavelength of
193 nm was performed on the manufactured transfer mask 200 of
Comparative Example 1. As a result of inspection of the image
transferred by exposure in this simulation, a transfer failure was
found. The cause for the failure seemed to be that the dry etching
for forming the second pattern in the light shielding film 4 in the
manufacture of the transfer mask 200 enlarged the film thickness
distribution in a plane of the etching mask film 3 to 5 nm or more,
which prevented the first pattern from being formed in the etching
mask film 3 with high accuracy, and thus eventually, the first
pattern could not be formed in the light-semitransmissive film 2
with high accuracy. According to this result, if the transfer mask
of Comparative Example 1 is set on the mask stage of the exposure
apparatus to perform the exposure transfer to the resist film on
the semiconductor device, a failure section would be developed in a
circuit pattern finally formed on the semiconductor device.
DESCRIPTION OF REFERENCE NUMERALS
[0180] 1: transparent substrate [0181] 1a: etched portion [0182] 2:
light-semitransmissive film (phase shift film) [0183] 2a:
light-semitransmissive pattern (light-semitransmissive film having
a first pattern) [0184] 3, 13: etching mask film [0185] 3a: etching
mask film having the first pattern [0186] 3b: etching mask pattern
(etching mask film having a second pattern) [0187] 4, 14: light
shielding film [0188] 4b: light shielding pattern (light shielding
film having the second pattern) [0189] 5b: resist pattern (first
resist film having the second pattern) [0190] 6a: resist pattern
(second resist film having the first pattern) [0191] 7b: resist
pattern (third resist film having the second pattern) [0192] 8, 18:
transfer pattern [0193] 13a: etching mask film having a third
pattern [0194] 13b: etching mask film having a fourth pattern
[0195] 14b: light shielding film having the fourth pattern [0196]
15b: resist pattern (fourth resist film having the fourth pattern)
[0197] 16a: resist pattern (fifth resist film having the third
pattern) [0198] 17b: resist pattern (sixth resist film having the
fourth pattern) [0199] 100, 110: mask blank [0200] 200, 210:
transfer mask
* * * * *