U.S. patent application number 15/898677 was filed with the patent office on 2019-03-14 for method of manufacturing semiconductor device.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Yasuki AIHARA, Kazuyuki ONOE, Takahiro UENO.
Application Number | 20190079400 15/898677 |
Document ID | / |
Family ID | 65631787 |
Filed Date | 2019-03-14 |
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United States Patent
Application |
20190079400 |
Kind Code |
A1 |
AIHARA; Yasuki ; et
al. |
March 14, 2019 |
METHOD OF MANUFACTURING SEMICONDUCTOR DEVICE
Abstract
A method of manufacturing a semiconductor device includes:
coating a first resist containing a photoacid generator or a
thermal acid generator on a semiconductor substrate; forming a
first opening portion in the first resist by optical exposure;
subjecting a shrink agent containing an acid to a crosslinking
reaction by the heat treatment to form a thermoset layer on an
overall surface of the first resist; coating a second resist on the
semiconductor substrate and the thermoset layer; and forming a
second opening portion located above the first opening portion and
larger than the first opening portion in the second resist by
optical exposure.
Inventors: |
AIHARA; Yasuki; (Tokyo,
JP) ; ONOE; Kazuyuki; (Tokyo, JP) ; UENO;
Takahiro; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
65631787 |
Appl. No.: |
15/898677 |
Filed: |
February 19, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/0272 20130101;
H01L 21/28587 20130101; G03F 7/40 20130101; G03F 7/168 20130101;
H01L 21/306 20130101; H01L 21/0273 20130101; G03F 7/0035
20130101 |
International
Class: |
G03F 7/16 20060101
G03F007/16; G03F 7/00 20060101 G03F007/00; G03F 7/40 20060101
G03F007/40; H01L 21/027 20060101 H01L021/027; H01L 21/306 20060101
H01L021/306 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 14, 2017 |
JP |
2017-176765 |
Claims
1. A method of manufacturing a semiconductor device comprising:
coating a first resist containing a photoacid generator or a
thermal acid generator on a semiconductor substrate; forming a
first opening portion in the first resist by optical exposure;
subjecting a shrink agent containing an acid to a crosslinking
reaction by the heat treatment to form a thermoset layer on an
overall surface of the first resist; coating a second resist on the
semiconductor substrate and the thermoset layer; and forming a
second opening portion located above the first opening portion and
larger than the first opening portion in the second resist by
optical exposure.
2. The method of manufacturing a semiconductor device according to
claim 1, further comprising: forming a metal film on the
semiconductor substrate, the thermoset layer and the second resist;
and removing the metal film on the second resist by lift-off,
wherein the second opening portion is formed in an overhang-shape
by using an image reversal resist as the second resist.
3. The method of manufacturing a semiconductor device according to
claim 1, further comprising: coating a third resist on the second
resist; and forming a third opening portion, which is located above
the first and second opening portions and is larger than the first
opening portion and smaller than the second opening portion, in the
third resist by optical exposure.
4. The method of manufacturing a semiconductor device according to
claim 1, wherein the step of forming the thermoset layer by making
the shrink agent cause the crosslinking reaction is repeated
multiple times.
5. The method of manufacturing a semiconductor device according to
claim 1, further comprising: forming a metal film on the
semiconductor substrate, the thermoset layer and the second resist;
forming a third resist which is larger than the second opening
portion on the metal film above the first and second opening
portions; and etching the metal film by using the third resist as a
mask.
6. The method of manufacturing a semiconductor device according to
claim 1, wherein an amount of the acid is controlled so that the
shrink agent does not cause a sufficient crosslinking reaction by
only the acid contained in the shrink agent.
7. The method of manufacturing a semiconductor device according to
claim 1, wherein the shrink agent contains a thermal acid generator
or a photoacid generator, and the acid is generated through heat
treatment or light irradiation.
8. A method of manufacturing a semiconductor device comprising:
coating a first resist which is an image reversal resist on a
semiconductor substrate; forming a first opening portion having an
overhang-shape in the first resist by optical exposure; subjecting
a shrink agent containing an acid to a crosslinking reaction by the
heat treatment to form a thermoset layer on an overall surface of
the first resist; coating a second resist on the semiconductor
substrate and the thermoset layer; and forming a second opening
portion arranged inside the first opening portion and smaller than
the first opening portion in the second resist by optical
exposure.
9. The method of manufacturing a semiconductor device according to
claim 8, wherein the step of forming the thermoset layer by making
the shrink agent cause the crosslinking reaction is repeated
multiple times.
10. The method of manufacturing a semiconductor device according to
claim 8, wherein an amount of the acid is controlled so that the
shrink agent does not cause a sufficient crosslinking reaction by
only the acid contained in the shrink agent.
11. The method of manufacturing a semiconductor device according to
claim 8, wherein the shrink agent contains a thermal acid generator
or a photoacid generator, and the acid is generated through heat
treatment or light irradiation.
Description
BACKGROUND OF THE INVENTION
Field
[0001] The present invention relates to a method of manufacturing a
semiconductor device forming a fine opening portion in a
resist.
Background
[0002] There has been disclosed a method of forming a fine opening
portion in a resist by using a shrink agent which causes a
crosslinking reaction with an acid occurring in the resist (for
example, see JP2003-7729A).
SUMMARY
[0003] The shrink agent contains a material which causes the
crosslinking reaction under the presence of an acid. A layer which
has been subjected to the crosslinking reaction is called as a
thermoset layer. A thermoset layer is formed around an opening
portion at which the acid occurring from the resist under exposure
remains. Furthermore, an acid also occurs when the resist is
subjected to heat treatment. Therefore, a thermoset layer is also
formed at other portions than the resist opening portion by a
conventional method, but the thus-formed thermoset layer is thin
and insufficient as compared with that at the opening portion.
Therefore, when a second resist is formed on a shrunk first resist,
mixing occurs between both the resists, which causes a problem that
it is impossible to stably form fine opening portions in the first
and second resists.
[0004] The present invention has been implemented to solve the
foregoing problem, and has an object to provide a method of
manufacturing a semiconductor device that is capable of stably
forming an opening portion in a resist.
[0005] According to the present invention, a method of
manufacturing a semiconductor device includes: coating a first
resist containing a photoacid generator or a thermal acid generator
on a semiconductor substrate; forming a first opening portion in
the first resist by optical exposure; subjecting a shrink agent
containing an acid to a crosslinking reaction by the heat treatment
to form a thermoset layer on an overall surface of the first
resist; coating a second resist on the semiconductor substrate and
the thermoset layer; and forming a second opening portion located
above the first opening portion and larger than the first opening
portion in the second resist by optical exposure.
[0006] Since the shrink agent containing the acid is used in the
present invention, a sufficiently thick thermoset layer can be
formed on the overall surface of the first resist. Furthermore, the
thick thermoset layer serves as a barrier to suppress the mixing
between the first resist and the second resist. As a result, the
first and second opening portions can be stably formed in the first
and second resists.
[0007] Other and further objects, features and advantages of the
invention will appear more fully from the following
description.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIGS. 1 to 5 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a first
embodiment.
[0009] FIGS. 6 and 7 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a second
embodiment
[0010] FIGS. 8 and 9 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a third
embodiment.
[0011] FIGS. 10 to 13 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a fourth
embodiment.
[0012] FIG. 14 is a cross-sectional view showing a method of
manufacturing a semiconductor device according to a fifth
embodiment.
[0013] FIGS. 15 to 18 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a sixth
embodiment.
DESCRIPTION OF EMBODIMENTS
[0014] A method of manufacturing a semiconductor device according
to the embodiments of the present invention will be described with
reference to the drawings. The same components will be denoted by
the same symbols, and the repeated description thereof may be
omitted.
First Embodiment
[0015] FIGS. 1 to 5 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a first
embodiment. As shown in FIG. 1, a first resist 2 is first coated on
a semiconductor substrate 1 of GaAs or the like. A first opening
portion 3 is formed in the first resist 2 by optical exposure. The
first resist 2 is Sumiresist PFI-58A6 manufactured by Sumitomo
Chemical Co. Ltd., for example. Here, the acid occurring from the
first resist 2 under exposure remains around the first opening
portion 3.
[0016] Next, a shrink agent 5 containing an acid 4 is coated on the
whole surface as shown in FIG. 2. The shrink agent 5 causes a
crosslinking reaction when it is subjected to heat treatment under
the presence of the acid 4. However, the amount of the acid 4 is
controlled so that the shrink agent 5 does not cause a sufficient
crosslinking reaction by only the acid 4 contained in the shrink
agent 5. Here, the sufficient crosslink reaction means that the
reaction progresses to the extent that a crosslinked product cannot
be removed by a developing processing. Addition of the acid
occurring from the first resist 2 through the heat treatment makes
the shrink agent 5 cause the crosslinking reaction, thereby forming
a thermoset layer 6 on the overall surface of the first resist
2.
[0017] Next, as shown in FIG. 3, a second resist 7 is coated on the
semiconductor substrate 1 and the thermoset layer 6. A second
opening portion 8 is formed in the second resist 7 by optical
exposure. The second opening portion 8 is located above the first
opening portion 3, and formed to be larger than the first opening
portion 3.
[0018] Next, a metal film 9 is formed on the semiconductor
substrate 1, the thermoset layer 6 and the second resist 7 as shown
in FIG. 4. Next, as shown in FIG. 5, the first and second resists 2
and 7, and the thermoset layer 6 are removed, and the metal film 9
on the second resist 7 is also removed by lift-off, thereby forming
a T-shaped electrode 10.
[0019] Here, since the first resist 2 contains a photoacid
generator or a thermal acid generator, a thermoset layer 6 is
formed on the surface of the first resist 2 by the acid occurring
from the first resist 2 under the exposure and under the heat
treatment even when the shrink agent 5 does not contain any acid 4.
However, since the amount of acid is insufficient, only a thin
thermoset layer 6 is formed, and mixing occurs between the first
resist 2 and the second resist 7, so that the first and second
opening portions 3 and 8 cannot be stably formed. On the other
hand, since the shrink agent 5 containing the acid 4 is used in
this embodiment, a sufficiently thick thermoset layer 6 can be
formed on the overall surface of the first resist 2. Furthermore,
the thick thermoset layer 6 serves as a barrier to suppress the
mixing between the first resist 2 and the second resist 7. As a
result, the first and second opening portions 3 and 8 can be stably
formed in the first and second resists 2 and 7.
Second Embodiment
[0020] FIGS. 6 and 7 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a second
embodiment. The steps up to the step of forming the thermoset layer
6 on the first resist 2 are the same as the steps of the first
embodiment. Next, as shown in FIG. 6, a second resist 7 which is an
image reversal resist is coated, and a second opening portion 8 is
formed in the second resist 7 by optical exposure.
[0021] Next, a metal film 9 is formed on the semiconductor
substrate 1, the thermoset layer 6 and the second resist 7 by vapor
deposition as shown in FIG. 7. Thereafter, the first and second
resists 2 and 7 and the thermoset layer 6 are removed, and the
metal film 9 on the second resist 7 is also removed by lift-off,
thereby forming a T-shaped electrode 10.
[0022] As described above, in this embodiment, the second opening
portion 8 is formed in an overhang-shape by using the image
reversal resist as the second resist 7. As a result, the metal film
9 on the second resist 7 and the metal film 9 in the second opening
portion 8 are easily separated, so that the T-shaped electrode 10
can be easily formed by a vapor deposition lift-off method.
Third Embodiment
[0023] FIGS. 8 and 9 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a third
embodiment. The steps up to the step of forming the thermoset layer
6 on the first resist 2 are the same as the steps of the first
embodiment. Next, as shown in FIG. 8, the second resist 7 is
coated, and a third resist 11 is coated on the second resist 7. All
of these resists are positive type photoresists, and a combination
of these resists is selected so that the second resist 7 has higher
exposure sensitivity than the third resist 11. A second opening
portion 8 is formed in the second resist 7 by optical exposure, and
a third opening portion 12 is formed in the third resist 11. The
optical exposure is performed under such a condition that the third
opening portion 12 is located above the first and second opening
portions 3 and 8, and is larger than the first opening portion 3
and smaller than the second opening portion 8. As a result, the
cross-sectional shapes of the second and third resists 7 and 11
become an overhang-shape.
[0024] Next, the metal film 9 is formed on the overall surface as
shown in FIG. 9. Thereafter, the first, second and third resists 2,
7 and 11 and the thermoset layer 6 are removed, and the metal film
9 on the third resist 11 is also removed by lift-off, thereby
forming a T-shaped electrode 10.
[0025] As described above, in this embodiment, the T-shaped
electrode 10 can be easily formed according to the vapor deposition
lift-off method by using the resist having the overhang-shaped
cross-section.
Fourth Embodiment
[0026] FIGS. 10 to 13 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a fourth
embodiment. As shown in FIG. 10, a first resist 2 which is an image
reversal resist is coated on the semiconductor substrate 1. A first
opening portion 3 having an overhang-shape is formed in the first
resist 2 by optical exposure. Next, as shown in FIG. 11, a shrink
agent 5 containing an acid 4 is coated, and the shrink agent 5 is
subjected to the crosslinking reaction by the heat treatment,
thereby forming the thermoset layer 6 on the overall surface of the
first resist 2.
[0027] Next, the second resist 7 is coated on the semiconductor
substrate 1 and the thermoset layer 6 as shown in FIG. 12. A second
opening portion 8 is formed in the second resist 7 by optical
exposure. The second opening portion 8 is arranged inside the first
opening portion 3, and set to be smaller than the first opening
portion 3.
[0028] Next, the metal film 9 is formed on the overall surface as
shown in FIG. 13. Thereafter, the first and second resists 2 and 7
and the thermoset layer 6 are removed, and the metal film 9 on the
second resist 7 is also removed by lift-off, thereby forming a
T-shaped electrode 10.
[0029] As described above, in this embodiment, the first resist 2
can be formed in an overhang-shape by using the image reversal
resist. Therefore, the T-shaped electrode 10 can be easily formed
by the vapor deposition lift-off method. The same other effects as
the first embodiment can be obtained.
Fifth Embodiment
[0030] FIG. 14 is a cross-sectional view showing a method of
manufacturing a semiconductor device according to a fifth
embodiment. In this embodiment, the step of forming the thermoset
layer 6 by making the shrink agent 5 cause the crosslinking
reaction in the first to third embodiments is repeated multiple
times, whereby the thermoset layer 6 on the surface of the first
resist 2 can be formed so as to have a large thickness. Since the
thermoset layer 6 is thick, the first opening portion 3 of the
first resist 2 can be further reduced in size. Furthermore, since a
large barrier effect for mixing can be obtained, the first and
second opening portions 3 and 8 can be more stably formed in the
first and second resists 2 and 7. The same effect can be also
obtained by repeating, multiple times, the step of making the
shrink agent 5 cause the crosslinking reaction in the fourth
embodiment to form the thermoset layer 6.
Sixth Embodiment
[0031] FIGS. 15 to 18 are cross-sectional views showing a method of
manufacturing a semiconductor device according to a sixth
embodiment. The steps up to the step of forming the thermoset layer
6 on the first resist 2 are the same as the steps of the first
embodiment. Next, as shown in FIG. 15, the second resist 7 is
coated on the semiconductor substrate 1 and the thermoset layer 6.
A second opening portion 8 which is located above the first opening
portion 3 and larger than the first opening portion 3 is formed in
the second resist 7 by optical exposure. Next, as shown in FIG. 16,
a metal film 9 is formed on the semiconductor substrate 1, the
thermoset layer 6 and the second resist 7 by a sputtering method.
Next, as shown in FIG. 17, a third resist 13 which is larger than
the second opening portion 8 is formed on the metal film 9 above
the first and second opening portions 3 and 8. Next, as shown in
FIG. 18, the metal film 9 is subjected to anisotropic etching by
using the third resist 13 as a mask according to a milling method
or the like. As a result, the T-shaped electrode 10 can be formed
without forming the second resist 7 in an overhang-shape.
[0032] In the first to sixth embodiments, a shrink agent 5
containing a thermal acid generator or a photoacid generator in
place of the acid 4 may be used. In this case, the same effect can
be obtained by generating the acid 4 through heat treatment and
light irradiation.
[0033] Obviously many modifications and variations of the present
invention are possible in the light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims the invention may be practiced otherwise than as
specifically described.
[0034] The entire disclosure of Japanese Patent Application No.
2017-176765, filed on Sep. 14, 2017 including specification,
claims, drawings and summary, on which the Convention priority of
the present application is based, is incorporated herein by
reference in its entirety.
* * * * *