U.S. patent application number 13/579490 was filed with the patent office on 2013-01-31 for copper oxide etchant and etching method using the same.
This patent application is currently assigned to ASAHI KASEI KABUSHIKI KAISHA. The applicant listed for this patent is Yoshimichi Mitamura, Norikiyo Nakagawa, Takuto Nakata. Invention is credited to Yoshimichi Mitamura, Norikiyo Nakagawa, Takuto Nakata.
Application Number | 20130026134 13/579490 |
Document ID | / |
Family ID | 44506552 |
Filed Date | 2013-01-31 |
United States Patent
Application |
20130026134 |
Kind Code |
A1 |
Nakagawa; Norikiyo ; et
al. |
January 31, 2013 |
COPPER OXIDE ETCHANT AND ETCHING METHOD USING THE SAME
Abstract
In order to provide a copper oxide etchant and an etching method
using the same capable of selectively etching exposure/non-exposure
portions when laser light exposure is performed by using copper
oxide as a thermal-reactive resist material, the copper oxide
etchant for selectively etching copper oxides having different
oxidation numbers in a copper oxide-containing layer containing the
copper oxide as a main component contains at least a chelating
agent or salts thereof.
Inventors: |
Nakagawa; Norikiyo; (Tokyo,
JP) ; Nakata; Takuto; (Tokyo, JP) ; Mitamura;
Yoshimichi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nakagawa; Norikiyo
Nakata; Takuto
Mitamura; Yoshimichi |
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP |
|
|
Assignee: |
ASAHI KASEI KABUSHIKI
KAISHA
Osaka-shi, Osaka
JP
|
Family ID: |
44506552 |
Appl. No.: |
13/579490 |
Filed: |
January 14, 2011 |
PCT Filed: |
January 14, 2011 |
PCT NO: |
PCT/JP2011/050549 |
371 Date: |
October 9, 2012 |
Current U.S.
Class: |
216/55 ;
252/79.1 |
Current CPC
Class: |
H01L 21/0337 20130101;
H01L 21/32134 20130101; B82Y 40/00 20130101; C09K 13/00
20130101 |
Class at
Publication: |
216/55 ;
252/79.1 |
International
Class: |
C09K 13/00 20060101
C09K013/00; B44C 1/22 20060101 B44C001/22 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2010 |
JP |
2010-039693 |
Feb 25, 2010 |
JP |
2010-040122 |
Jul 7, 2010 |
JP |
2010-154855 |
Dec 17, 2010 |
JP |
2010-282267 |
Claims
1. A copper oxide etchant for selectively etching copper oxides
having different oxidation numbers in a copper oxide-containing
layer containing copper oxide as a main component, wherein the
copper oxide etchant contains at least a chelating agent or a salt
thereof.
2. The copper oxide etchant according to claim 1, wherein the
chelating agent contains at least one element selected from a group
consisting of amino acids such as alanine, arginine, asparagine,
aspartic acid, cysteine, glutamine, glutamic acid, glycine,
histidine, isoleucine, leucine, lysine, methionine, ornithine,
phenylalanine, serine, threonine, tryptophan, tyrosine, valine, and
proline, or other chelating agents such as oxalic acid,
ethylenediaminetetraacetic acid,
hydroxyethylethylenediaminetriacetic acid,
dihydroxyethylethylenediaminediaceticacid,
1,3-propanediaminetertaacetic acid, citric acid, fumaric acid,
adipic acid, succinic acid, malic acid, tartaric acid, and
bathocuproinesulfonic acid, or salts thereof.
3. The copper oxide etchant according to claim 1 or 2, wherein the
chelating agent contains at least one of the amino acids.
4. The copper oxide etchant according to claim 3, wherein the amino
acid contains at least one element selected from a group consisting
of glycine, alanine, ornithine, and lysine.
5. The copper oxide etchant according to claim 1, wherein a ratio
of the chelating agent in the copper oxide etchant is equal to or
greater than 0.00001 mass % and equal to or smaller than 10 mass
%.
6. An etching method using the copper oxide etchant according to
claim 1, the etching method comprising: a thermal decomposition
process for thermally decomposing copper oxide in a predetermined
area of a copper oxide-containing layer containing copper oxide;
and an etching process for supplying the copper oxide etchant to
the copper oxide-containing layer to remove copper oxide in a
predetermined area thermally decomposed from the copper
oxide-containing layer.
7. The etching method according to claim 6, wherein, in the etching
process, a liquid discharge pressure when the copper oxide etchant
is applied is equal to or greater than 0.005 MPa and equal to or
smaller than 0.15 MPa.
Description
TECHNICAL FIELD
[0001] This disclosure relates to a copper oxide etchant and an
etching method used in an etching process in a micropatterning
technology in which copper oxide is used as a thermal-reactive
resist material.
BACKGROUND
[0002] In recent years, as demands for a high density and a high
integration increase in the fields of semiconductors,
optical/magnetic recordings, and the like, a micropatterning
technology capable of patterning a size of several tens to several
hundreds nanometers or smaller becomes indispensable. In this
regard, a lot of researches have been made for elemental techniques
in each process such as masks/steppers, exposure, and resist
materials in order to implement such a micropatterning.
[0003] Although many studies have been made for resist materials,
the resist material most widely used at this time is a
photo-reactive organic resist (hereinafter, also referred to as a
"photoresist") that reacts to an exposure light source such as
infrared light, an electron ray, and an X-ray (e.g., refer to
Patent Literature 1 and Non-Patent Literature 1).
[0004] In the laser light used in exposure, the laser light
intensity typically adjusted using a lens has a Gaussian
distribution as illustrated in FIG. 1, where a spot diameter is
defined as 1/e.sup.2. In general, reaction of the photoresist is
initiated when energy expressed as E=h.nu. (where E denotes energy,
h denotes a Frank' s constant, and .nu. denotes a wavelength) is
absorbed. Therefore, since the reaction does not strongly depend on
the light intensity, but depends on the wavelength of light, almost
the entire portion where light is irradiated generates reaction
(light irradiation portion.apprxeq.exposure portion). For this
reason, when the photoresist is used, reliable exposure would be
achieved for the spot diameter.
[0005] The technique of using the photoreactive organic resist is
very effective to form a fine pattern having a size of several
hundreds nanometers. However, it is necessary to perform exposure
with a spot diameter smaller than that of the pattern required in
principle in order to use the photoreactive photoresist and form
the fine pattern. Therefore, it is necessary to use KrF laser or
ArF laser having a short wavelength as the exposure light source.
However, such a light source unit is large-sized and expensive, and
thus, it is not suitable in terms of reduction of the manufacturing
cost. In addition, when an exposure light source such as an
electron ray or an X-ray is used, it is necessary to provide an
exposure atmosphere in a vacuum state. Therefore, a vacuum chamber
is employed. This gives a considerable limitation in terms of the
cost or the large size.
[0006] Meanwhile, if laser light having an intensity distribution
illustrated in FIG. 1 is irradiated onto an object, a temperature
of the object also exhibits a Gaussian distribution similar to the
intensity distribution of the laser light. In this case, if a
resist that reacts at a certain temperature or higher, i.e., a
thermal-reactive resist is used, the reaction is processed in only
the portion heated up to a predetermined temperature or higher as
illustrated in FIG. 2. Therefore, it is possible to exposure a
range smaller than the spot diameter (light irradiation
portion.noteq.exposure portion). That is, it is possible to form a
fine pattern having a size smaller than the spot diameter without
shortening the wavelength of the exposure light source. Therefore,
it is possible to alleviate influence of the wavelength of the
exposure light source by using the thermal-reactive resist.
[0007] Until now, techniques have been reported for forming a fine
pattern through exposure or thermal/optical reaction caused by
semiconductor laser and the like by using WOx, MoOx, noble metal
oxides, and the like as a thermal-reactive resist (e.g., refer to
Patent Literatures 2 to 4 and Non-Patent Literature 2). WOx and
MoOx are known as a resist material called imperfect oxide having a
degree of oxidation X smaller than that of perfect oxide. The
degree of oxidation X is changed by heating through exposure, and a
difference of solubility for the etchant is generated due to a
difference of the degree of oxidation, so that a fine pattern can
be formed through etching. For this reason, the etching
characteristic is changed by a slight difference of the degree of
oxidation X, so that a very high technique is necessary to
manufacture a resist having excellent reproducibility based on a
lot of parameters such as a condition of the start material, a
method of forming a film, and an exposure method. In addition,
tungsten (W) or molibdenum (Mo) problematically has a low
resistance to a dry etching using a fluorine-based gas.
[0008] Meanwhile, noble metal oxide may be used to form the fine
pattern by generating decomposition of noble metal oxide through
thermal reaction, optical reaction, and the like and performing
etching based on a difference of solubility for the etchant
generated between decomposed and undecomposed portions. This
technique is characterized in that a resist having excellent
reproducibility can be obtained without significantly being
influenced from a condition of the start material (for example, a
slight difference of the degree of oxidation) because the material
is decomposed at a certain temperature (decomposition temperature)
in the case of, for example, thermal reaction. However, although
the noble metal oxide used as the decomposed material in Patent
Literatures 3 and 4 allows for pattern formation by generating
decomposition reaction such as thermal reaction, optical reaction,
and the like, a material particle growth is also generated along
with the decomposition. Therefore, this technique takes only a
sea-island structure in which a resist portion remaining after the
etching is at random, and it is difficult to control a pattern size
in a uniform convex-concavo or line-shaped fine pattern and the
like.
[0009] The copper oxide as noble metal oxide generates abrupt
decomposition to discharge oxygen when it reaches a decomposition
temperature, and its particle growth is suppressed in comparison
with the noble metal oxide used in Patent Literatures 3 and 4.
Therefore, the copper oxide is an effective resist material for
forming a fine pattern. However, although there are a number of
etchants for copper as disclosed in Patent Literatures 5 to 8,
there has not been reported for the selective etching of
exposure/non-exposure portions with high precision when exposure is
performed using noble metal oxide, particularly, copper oxide.
[Citation List]
[Patent Literatures]
[0010] [Patent Literature 1] Japanese Patent Application Laid-open
No. 2007-144995
[0011] [Patent Literature 2] Japanese Patent No. 4055543
[0012] [Patent Literature 3] Japanese Patent Application Laid-open
No. 2008-143162
[0013] [Patent Literature 4] Japanese Patent Application Laid-open
No. 2008-168610
[0014] [Patent Literature 5] Japanese Patent Application Laid-open
No. 2005-105410
[0015] [Patent Literature 6] Japanese Patent Application Laid-open
No. 2005-105333
[0016] [Patent Literature 7] Japanese Patent Application Laid-open
No. 2001-262374
[0017] [Patent Literature 8] Japanese Patent Application Laid-open
No. 2008-088541
[Non-patent Literatures]
[0018] [Non-patent Literature 1] "Advanced Resist Material," pages
59 to 76, published by JOHOKIKO Co. Ltd., in Tokyo, Japan
[0019] [Non-patent Literature 2] The 19th Symposium on Phase Change
Optical Information Storage, 2007, preceding, pages 77 to 80
SUMMARY OF INVENTION
Technical Problem
[0020] A need thus exists for a copper oxide etchant and an etching
method using the same capable of selectively etching exposure
portions and non-exposure portions when laser light exposure is
performed by using copper oxide as a thermal-reactive resist
material.
Solution to Problem
[0021] The inventors made diligent studies and experiments for
addressing the problems described above. As a result, the inventors
found out a fact that the selective etching of
exposure/non-exposure portions can be achieved when exposure is
performed by using copper oxide as a thermal-reactive resist
material in a solution containing at least a chelating agent and
complete the disclosure based on this fact. That is, the disclosure
is as follows.
[0022] According to an aspect of the disclosure, there is provided
a copper oxide etchant for selectively etching copper oxides having
different oxidation numbers in a copper oxide-containing layer
containing copper oxide as a main component, wherein the copper
oxide etchant contains at least a chelating agent or a salt
thereof.
[0023] In the copper oxide etchant of the disclosure, it is
preferable that the chelating agent contain at least one element
selected from a group consisting of amino acids such as alanine,
arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic
acid, glycine, histidine, isoleucine, leucine, lysine, methionine,
ornithine, phenylalanine, serine, threonine, tryptophan, tyrosine,
valine, and proline, or other chelating agents such as oxalic acid,
ethylenediaminetetraacetic acid,
hydroxyethylethylenediaminetriacetic acid,
dihydroxyethylethylenediaminediacetic acid,
1,3-propanediaminetertaacetic acid, citric acid, fumaric acid,
adipic acid, succinic acid, malic acid, tartaric acid, and
bathocuproinesulfonic acid, or salts thereof.
[0024] In the copper oxide etchant of the disclosure, it is
preferable that the chelating agent contain at least one of the
amino acids.
[0025] In the copper oxide etchant of the disclosure, it is
preferable that the amino acid contain at least one element
selected from a group consisting of alanine, glycine, lysine, or
ornithine.
[0026] In the copper oxide etchant of the disclosure, it is
preferable that a ratio of the chelating agent in the copper oxide
etchant is equal to or greater than 0.00001 mass % and equal to or
smaller than 10 mass %.
[0027] According to another aspect of the disclosure, there is
provided an etching method using the copper oxide etchant described
above, the etching method including: a thermal decomposition
process for thermally decomposing copper oxide in a predetermined
area of a copper oxide-containing layer containing copper oxide;
and an etching process for supplying the copper oxide etchant to
the copper oxide-containing layer to remove copper oxide in a
predetermined area thermally decomposed from the copper
oxide-containing layer.
[0028] In the etching method of the disclosure, in the etching
process, a liquid discharge pressure when the copper oxide etchant
is applied is equal to or greater than 0.005 MPa and equal to or
smaller than 0.15 MPa.
Technical Advantages of the Invention
[0029] According to this disclosure, it is possible to provide a
copper oxide etchant and an etching method using the same capable
of selectively etching exposure/non-exposure portions when laser
light exposure is performed by using copper oxide as a
thermal-reactive resist material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a diagram illustrating an intensity distribution
of laser light;
[0031] FIG. 2 is a diagram illustrating a temperature distribution
on the portion where laser light is irradiated;
[0032] FIG. 3 is a diagram illustrating a thermogravimetric
measurement result of copper oxide (II);
[0033] FIG. 4 is a diagram illustrating an X-ray diffraction
measurement result for copper oxide (I) and copper oxide (II);
[0034] FIG. 5 is a photograph obtained by taking an atomic force
microscope (AFM) image of the copper oxide film subjected to the
etching of Example 1 disclosed herein;
[0035] FIG. 6 is a photograph obtained by taking an AFM image of
the copper oxide film subjected to the etching of Example 2
disclosed herein;
[0036] FIG. 7 is a photograph obtained by taking an AFM image of
the copper oxide film subjected to the etching of Example 3
disclosed herein;
[0037] FIG. 8 is a photograph obtained by taking an AFM image of
the copper oxide film subjected to the etching of Example 4
disclosed herein;
[0038] FIG. 9 is a photograph obtained by taking an AFM image of
the copper oxide film subjected to the etching of Example 5
disclosed herein;
[0039] FIG. 10 is a photograph obtained by taking an AFM image of
the copper oxide film subjected to the etching of Example 7
disclosed herein;
[0040] FIG. 11 is a photograph obtained by taking an AFM image of
the copper oxide film subjected to the etching of Example 20
disclosed herein; and
[0041] FIG. 12 is a photograph obtained by taking an AFM image of
the copper oxide film subjected to the etching of Example 23
disclosed herein.
DESCRIPTION OF EMBODIMENTS
[0042] The inventors made diligent efforts to achieve a
micropatterning technology capable of forming a fine pattern with a
high aspect ratio. Since the entire organic resist material in the
exposure portion is reacted when an organic resist material is used
to form the fine pattern, the micropatterning precision is limited
by the wavelength of laser light. Meanwhile, in a thermal-reactive
resist material thermally reacted by heating, only the region where
a temperature reaches a certain temperature (decomposition
temperature) is thermally reacted. For this reason, if the
thermal-reactive resist material is used to form the fine pattern,
it is possible to form the fine pattern having a wavelength equal
to or shorter than that of laser light.
[0043] The inventors focused on copper oxides as the
thermal-reactive resist material. As the copper oxides, there are
known copper oxide (II) and copper oxide (I). If the copper oxide
(II) is heated to a certain temperature or higher, oxygen is
discharged, and copper oxide (II) is reduced to copper oxide (I).
Since the thermal decomposition reaction from copper oxide (II) to
copper oxide (I) is processed abruptly, it is possible to
selectively perform thermal decomposition from copper oxide (II) to
copper oxide (I) in a desired area of the thermal-reactive resist
material by appropriately controlling a heating temperature. For
this reason, it is possible to form a fine pattern with a high
aspect ratio by using a copper oxide etchant for selectively
dissolving the copper oxide (I) in the thermal-reactive resist
material subjected to the thermal decomposition.
[0044] The inventors made diligent studies for the copper oxide
etchant selectively reacted with the copper oxide (I). As a result,
the inventors found out a fact that copper oxide (I) can be
selectively dissolved from a resist material in which copper oxides
having different oxidation numbers are mixedly contained after
thermal decomposition, and a fine pattern can be formed with a high
aspect ratio if a copper oxide etchant containing a predetermined
chelating agent or salts thereof is used. Finally, the inventors
achieve the present disclosure based on this fact.
[0045] Hereinafter, embodiments of the disclosure will be described
with reference to the accompanying drawings.
[0046] An etching target of the copper oxide etchant disclosed
herein is copper oxide. For example, the copper oxide etchant is
used for selectively etching the exposure/non-exposure portions
when laser light exposure is performed by using a copper
oxide-containing layer containing the copper oxide as a main
component as a thermal-reactive resist material.
[0047] The copper oxide etchant disclosed herein contains at least
a chelating agent and is, particularly, a solution obtained by
mixing water. In the copper oxide used as the thermal-reactive
resist material, oxygen is discharged, and decomposition is
generated when a decomposition temperature is reached by the heat
caused by laser light exposure, so that copper oxide having a
different structure and a different composition with a lower degree
of oxidation, compared to those before the exposure is performed,
is obtained. If a copper oxide etchant containing at least the
chelating agent is reacted with such copper oxide having at least
two types of oxidation states with a different structure and a
different composition obtained by the exposure, it is possible to
selectively dissolve the copper oxide in the exposure portion, by
reacting the chelating agent with the copper oxide after the
exposure. In this disclosure, the chelating agent refers to an
organic acid having a plurality of carboxyl groups or amino groups
in the same molecule and capable of being coordinated with copper
in at least two or more functional groups.
[0048] Although the structure and the composition of copper oxide
are changed by the laser light exposure by way of example herein,
any method may be employed without limiting to laser light
irradiation if it can decompose copper oxide by heating a
predetermined area in the copper oxide-containing layer to a
predetermined temperature or higher. In addition, "containing
copper oxide as a main component" means that a composition of the
copper oxide-containing layer includes copper oxide of 50 mass %,
preferably, 70 mass % or higher, more preferably, 80 mass % or
higher, and, most preferably, 90 mass or higher. However, the upper
limit is set to 100 mass % or lower. If the ratio of copper oxide
is lower than 50 mass %, the decomposition reaction of copper oxide
is not uniformly processed, so that it is difficult to achieve the
selective etching.
[0049] Specifically, the chelating agent used in this disclosure
may include amino acids such as alanine, arginine, asparagine,
aspartic acid, cysteine, glutamine, glutamic acid, glycine,
histidine, isoleucine, leucine, lysine, methionine, ornithine,
phenylalanine, serine, threonine, tryptophan, tyrosine, valine, and
proline, or chelating agents other than the amino acids such as
oxalic acid, ethylenediaminetetraacetic acid,
hydroxyethylethylenediaminetriacetic acid,
dihydroxyethylethylenediaminediacetic acid,
1,3-propanediaminetertaacetic acid, diethylenetriaminepentaacetic
acid, triethylenetetraaminehexaacetic acid, 1,2-diaminopropane
tetraacetic acid, ethylenediaminedisuccinic acid,
dihydroxyethylethylenediaminemonosuccinic acid, 1,3-propanediamine
disuccinic acid, triethylenetetraminetrisuccinic acid,
1,2-diaminopropane disuccinic acid, ethylenediaminetetrapropionic
acid, hydroxyethylethylenediaminetripropionic acid,
dihydroxyethylethylenediaminedipropionic acid, 1,3-propanediamine
tetrapropionic acid, diethylenetriaminepentapropionic acid,
triethylenetetraminehexapropionic acid, 1,2-diaminopropane
tetraacetic acid, citric acid, isocitric acid, fumaric acid, adipic
acid, succinic acid, glutamic acid, malic acid, tartaric acid, and
bathocuproinedisulfonic acid. In addition, the chelating agent used
in this disclosure may include salts such as lithium salts, sodium
salts, potassium salts, ammonium salts, calcium salts, magnesium
salts, polyalkyl ammonium salts, polyaryl ammonium salts, or
hydrochloride salts thereof. As the salts of the chelating agent,
if a plurality of carboxylic acids, sulfonic acids, and the like
are contained, overall carboxylic acids and sulfonic acids may be
salts, or a part of carboxylic acids and sulfonic acids may be
salts.
[0050] The chelating agent and the salt thereof disclosed herein
contain at least one of the aforementioned chelating agents and
salts thereof. Out of such chelating agents, in terms of
availability and water solubility, the chelating agent preferably
includes alanine, arginine, asparagine, aspartic acid, cysteine,
glutamine, glutamic acid, glycine, histidine, isoleucine, leucine,
lysine, methionine, ornithine, phenylalanine, serine, threonine,
tryptophan, tyrosine, valine, or proline. In addition, the
chelating agent preferably includes oxalic acid,
ethylenediaminetetraacetic acid,
hydroxyethylethylenediaminetriacetic acid,
dihydroxyethylethylenediaminediacetic acid,
1,3-propanediaminetertaacetic acid, citric acid, fumaric acid,
adipic acid, succinic acid, malic acid, tartaric acid,
bathocuproinesulfonic acid, or salts thereof. More preferably, the
chelating agent includes glycine, alanine, histidine, isoleucine,
leucine, lysine, methionine, ornithine, phenylalanine, serine,
threonine, tryptophan, tyrosine, valine, ethylenediaminetetraacetic
acid, hydroxyethylethylenediaminetriacetic acid, citric acid,
bathocuproinedisulfonic acid, or salts thereof. Particularly, the
chelating agent preferably includes glycine, alanine, ornithine,
lysine, or salts thereof.
[0051] If such a chelating agent is contained, activation energy
necessary in complexation between the chelating agent and the
copper oxide having a degree of oxidation changed by exposure is
lower than activation energy necessary in complexation between the
chelating agent and the copper oxide before exposure. Therefore,
the complexation reaction between the chelating agent and the
copper oxide having a degree of oxidation changed by exposure is
rapidly processed. In addition, since the stability of the
complexation product of the copper oxide after exposure is higher
than that of the copper oxide before exposure, it is possible to
selectively dissolve the copper oxide in the exposure portion.
[0052] Since the chelating agent contains at least one of the amino
acids, formation of chelate with the copper oxide having a degree
of oxidation changed by exposure is more rapidly processed. In
addition, since the stability of the complexation product of the
copper oxide after exposure is also higher than that of the copper
oxide before exposure, it is possible to more selectively dissolve
the copper oxide in the exposure portion.
[0053] If the chelating agent contains at least one of amino acids
selected from a group consisting of glycine, alanine, ornithine, or
lysine, water solubility is particularly high. Therefore, a
concentration controllable range is wide, and formation of chelate
with the copper oxide having a degree of oxidation changed by
exposure is more rapidly processed. Furthermore, since the
stability of the complexation product is high as the copper oxide
after exposure is stable, it is possible to particularly
selectively dissolve the copper oxide in the exposure portion.
[0054] Some of the aforementioned chelating agent may be used as a
copper etchant. However, even when some of the aforementioned
chelating agent may be used as a copper etchant in general, they
may not be used as a selective etchant for a mixture of the copper
oxides having different oxidation numbers. For example, although
the etchant containing a copper ammine complex and the like may be
used as a copper etchant, it is difficult to sufficiently obtain a
difference of the complexation constant caused by the valence using
such an etchant. Therefore, it is difficult to selectively etch a
mixture of copper oxides having different oxidation numbers.
[0055] In the copper oxide etchant disclosed herein, other
components such as acid or alkali, an oxidizing agent, and a
surfactant may be added with an arbitrary concentration if it does
not hinder a chelating reaction between the copper oxide and the
chelating agent.
[0056] As the oxidizing agent, any typical oxidizing agent may be
used without a particular limitation. Specifically, the oxidizing
agent may include, for example, hydrogen peroxide, sodium
permanganate, potassium permanganate, ammonium permanganate,
calcium permanganate, magnesium permanganate, silver permanganate,
barium permanganate, lithium chlorate, sodium chlorate, potassium
chlorate, ammonium chlorate, lithium bromate, sodium bromate,
potassium bromate, ammonium bromate, lithium iodate, sodium iodate,
potassium iodate, ammonium iodate, perchloric acid, lithium
perchlorate, sodium perchlorate, potassium perchlorate, ammonium
perchlorate, calcium perchlorate, silver perchlorate, perbromic
acid, lithium perbromate, sodium perbromate, potassium perbromate,
ammonium perbromate, calcium perbromate, silver perbromate,
periodic acid, lithium periodate, sodium periodate, potassium
periodate, ammonium periodate, calcium periodate, silver periodate,
dichromic acid, lithium dichromate, sodium dichromate, potassium
dichromate, calcium dichromate, magnesium dichromate, osmium
tetroxide, meta-chloroperoxybenzoic acid, lithium persulfate,
sodium persulfate, potassium persulfate, ammonium persulfate, or
iron chloride. Out of these oxidizing agents, in terms of
availability, safety, and environmental burdens, the oxidizing
agent preferably includes hydrogen peroxide, potassium
permanganate, lithium persulfate, sodium persulfate, potassium
persulfate, ammonium persulfate, or iron chloride. Most preferably,
the oxidizing agent includes hydrogen peroxide, sodium persulfate,
potassium persulfate, ammonium persulfate, or iron chloride.
[0057] Any surfactant may be used as the aforementioned surfactant
without a particular limitation if wettability or permeability is
improved. A surfactant commercially available in the market may be
directly used or may be synthesized. The surfactant may include an
anionic system, a cationic system, a nonionic system, or an
amphoterism. Out of them, preferably, the surfactant includes the
anionic system, the nonionic system, or the amphoterism. More
preferably, the surfactant includes the anionic system or the
nonionic system. Such a surfactant may be solely used, or two or
more types of surfactants may be mixedly used.
[0058] The anionic system surfactant may include a carboxylic acid
type, a sulfonic acid type, a sulfuric acid ester type, and a
phosphoric acid ester type. In addition, the nonionic system
surfactant may include a polyethylene glycole type, a polyalkylene
glycol type, a polyhydric alcohol type, and an acetylene type.
Specifically, the anionic system surfactant may include olefin
sulfonic acid, alkyl sulfonic acid, benzene sulfonic acid, alkyl
sulfonic acidester, alkyl ether sulfateester, alkylcarboxylic acid,
perfluoroalkyl sulfonic acid, monoalkyl phosphoric acid, salts
thereof, and the like. Out of them, lithium monododecyl phosphate,
sodium monododecyl phosphate, or potassium monododecyl phosphate is
preferably used. The nonionic system surfactant may include
poly(oxyethylene)alkyl ether, poly(oxyethylene) fatty acid ester,
polyethylene glycole, polyoxyethylenepolyoxypropylene ether,
glycerine fatty acid ester, acetylene diol, acetylene glycol, and
the like. Out of them, poly(oxyethylene)alkyl ether,
poly(oxyethylene) fatty acid ester, acetylene diol, or the like is
preferably used.
[0059] If the copper oxide etchant has high foamability, etching
irregularity is easily generated due to the foam. Therefore, a
surfactant having low foamability may be used, or a surfactant
having a defoaming action may be simultaneously added.
[0060] In the copper oxide etchant disclosed herein, the etch rate
can be controlled by adjusting a concentration of the chelating
agent. That is, if the concentration of the chelating agent
increases, the etch rate increases. On the contrary, if the
concentration of the chelating agent decreases, the etch rate
decreases. The concentration may increase If the rate is too low to
give reasonable efficiency, and may be appropriately selected based
on a thickness of the resist, desired regularity or efficiency, or
the like. From the viewpoint described above, the concentration of
the chelating agent for the entire copper oxide etchant is
preferably set to be equal to or greater than 0.00001 mass % and be
equal to or smaller than 10 mass %, more preferably, equal to or
greater than 0.00001 mass % and equal to or smaller than 1 mass %,
and most preferably, equal to or greater than 0.01 mass % and equal
to or smaller than 1 mass %. In addition, for the amino acids, the
concentration of the chelating agent is preferably set to be equal
to or greater than 0.01 mass % and equal to or smaller than 10 mass
%, more preferably, equal to or greater than 0.1 mass % and equal
to or smaller than 10 mass %, and most preferably, equal to or
greater than 0.1 mass % and equal to or smaller than 3 mass %.
[0061] The oxidizing agent disclosed herein is used to adjust an
electric potential of the etchant. If the concentration of the
oxidizing agent is too low, it is difficult to process the etching.
If the concentration of the oxidizing agent is too high, the
etching selectivity may be degraded. From the viewpoint described
above, the concentration of the oxidizing agent for the entire
etchant is preferably set to be equal to or greater than 0.01 mass
% and equal to or smaller than 1 mass %, and more preferably, equal
to or greater than 0.1 mass % and equal to or smaller than 1 mass
%.
[0062] The surfactant disclosed herein is used to improve
wettability and permeability of the etchant. If the amount of the
surfactant is extremely small, the effect is poor. On the contrary,
if the concentration of the surfactant is too high, foaming is
significantly generated, and this causes etching irregularity and
the like. From the viewpoint described above, the concentration of
the surfactant for the entire etchant is preferably set to be equal
to or greater than 0.00001 mass % and equal to or smaller than 1
mass %, more preferably, equal to or greater than 0.0001 mass and
equal to or smaller than 0.1 mass %, and most preferably, equal to
or greater than 0.01 mass % and equal to or smaller than 0.1 mass
%.
[0063] The pH value of the copper oxide etchant disclosed herein is
mostly set to be equal to or greater than 1 and equal to or smaller
than 11 depending on the type of the chelating agent. However, the
pH value may be changed within this range by adding any acid or
alkali without degrading the effects. Unfortunately, a desired
effect may not be obtained if any acid or alkali that promotes or
inhibits complexation or that generates oxidation or reduction to
remarkably change an electric potential.
[0064] Furthermore, a desired effect may not be obtained if the pH
value is significantly deviated from the pH range set to be equal
to or greater than 1 and equal to or smaller than 11, so that the
etching is processed in a different mechanism. The acid or the
alkali that preferably satisfies the aforementioned condition may
include hydrochloric acid, sulfuric acid, nitric acid, ammonia,
potassium hydroxide, sodium hydroxide, or tetramethylammonium
hydroxide. More preferably, the acid or the alkali includes
hydrochloric acid, sulfuric acid, ammonia, or tetramethylammonium
hydroxide.
[0065] How to react the copper oxide etchant with the resist is not
particularly limited. The resist may be immersed into the copper
oxide etchant, or the etchant may be sprayed to the resist. When
the resist is immersed into the copper oxide etchant, the etch rate
can increase by increasing the amount of the etchant corresponding
to the resist per unit time by circulating the etchant or operating
the resist. In addition, when the copper oxide etchant is sprayed
to the resist, the etch rate can increase by increasing the liquid
discharge pressure. However, if the discharge pressure is too high,
the selectivity and the regularity of etching may be degraded. In
addition, if the discharge pressure is too low, the sprayed etchant
is not applied regularly, so that the regularity of etching may be
degraded. In this regard, the discharge pressure is preferably set
to be equal to or greater than 0.005 MPa and equal to or smaller
than 0.15 MPa, more preferably, equal to or greater than 0.01 MPa
and equal to or smaller than 0.10 MPa, and most preferably, equal
to or greater than 0.01 MPa and equal to or smaller than 0.05 MPa.
When the copper oxide etchant is sprayed to the resist, the nozzle
may move, or the resist may rotate, and the like. Preferably, such
a method may be employed solely or in combination to process the
etching regularly. Any type of the nozzle may be used in spraying.
For example, the nozzle may be a line slit, a full cone nozzle, a
hollow cone nozzle, a flat nozzle, a uniform flat nozzle, a solid
nozzle, and the like. The nozzle may be selected depending on a
shape of the resist or the base material. Naturally, a plurality of
nozzles may be arranged side by side, and either single-fluid
nozzle or two-fluid nozzle may be used.
[0066] The etch rate can be changed by controlling the temperature
when the copper oxide etchant is applied to the resist. Any
temperature may be set if it does not freeze or boil the copper
oxide etchant, volatilize the copper oxide etchant at a rate where
the concentration abruptly changes, or decompose the resist or a
component of the copper oxide etchant. For the reason described
above, the temperature range is preferably set to be equal to or
higher than 0.degree. C. and equal to or lower than 80.degree. C.,
more preferably, equal to or higher than 10.degree. C. and equal to
or lower than 60.degree. C., even more preferably, equal to or
higher than 10.degree. C. and equal to or lower than 40.degree. C.,
and most preferably, equal to or higher than 20.degree. C. and
equal to or lower than 40.degree. C.
[0067] If there is an impurity such as insoluble fine powder in the
copper oxide etchant when the copper oxide etchant is applied to
the resist, it may cause irregularity in etching of the fine
pattern. Therefore, the copper oxide etchant is preferably filtered
in advance. Any material may be selected for the filter used in the
filtering if it does not react with the copper oxide etchant. For
example, PFA, PTFE, and the like may be used. The roughness of the
filter may be selected based on a pattern precision, and is
generally set to be equal to or smaller than 0.2 .mu.m, and more
preferably, equal to or smaller than 0.1 .mu.m. In addition, in
order to prevent eduction or re-deposition of the eluted component,
spraying is more preferable than immersion. In addition, when the
copper oxide etchant is sprayed to the resist, the etchant is
preferably disposable. When the copper oxide etchant is reutilized,
the eluted component is preferably removed.
[0068] A base material of the resist where the copper oxide etchant
disclosed herein is applied is not particularly limited by a
material or a shape. However, the material of the resist preferably
has excellent surface flatness and processability.
[0069] Such a material may include glass, silicon, silicon dioxide,
aluminum, titanium, copper, silver, gold, and the like.
Particularly, the material preferably includes glass, silicon,
silicon dioxide, aluminum, titanium, or copper. In addition, the
shape of the resist may be two-dimensional such as a flat plate or
three-dimensional such as a roll.
[0070] Next, description will be made for an etching method using
the copper oxide etchant described above. The etching method
disclosed herein includes a thermal decomposition process for
thermally decomposing copper oxide in a predetermined area of the
copper oxide-containing layer which contains copper oxide and an
etching process for supplying the copper oxide-containing layer
with the copper oxide etchant and removing a predetermined area of
the thermally decomposed copper oxide from the copper
oxide-containing layer.
[0071] In the thermal decomposition process, the copper oxide in a
predetermined area of the copper oxide layer is thermally
decomposed by adding heat of a predetermined temperature or higher
to a predetermined area of the copper oxide-containing layer. In
addition, in the thermal decomposition process, the thermal
decomposition in the copper oxide-containing layer is preferably
performed by irradiating laser light onto the copper
oxide-containing layer. Since the temperature of a predetermined
area of the copper oxide-containing layer has a Gaussian
distribution (refer to FIG. 2) by irradiating laser light onto a
predetermined area of the copper oxide layer, reaction is generated
in only the portion of a predetermined temperature or higher, and
it is possible to thermally decompose a range smaller than the spot
diameter of the laser light. In addition, the thermal decomposition
may be performed without limiting to laser light if the copper
oxide can be decomposed by adding heat of a predetermined
temperature or higher to a predetermined area of the copper
oxide-containing layer.
[0072] In the etching process, the copper oxide etchant is supplied
to the copper oxide-containing layer to remove copper oxide in a
predetermined area of the copper oxide-containing layer by
resolution. In the copper oxide-containing layer after the thermal
decomposition process, there are copper oxide that is not thermally
decomposed and copper oxide having a reduced oxidation number due
to the thermal decomposition. Since the chelating agent in the
copper oxide etchant is selectively reacted with the copper oxide
having a reduced oxidation number due to the thermal decomposition,
it is possible to selectively remove copper oxide in the copper
oxide area thermally decomposed from the copper oxide-containing
layer by resolution.
[0073] The etching method disclosed herein preferably includes a
process of cleaning the etching layer (copper oxide- containing
layer) and a process of cleaning the base material and the etching
layer after the etching.
Examples
[0074] Hereinafter, description will be made for examples performed
to make the effects of the disclosure apparent, but they are not
intended to limit this disclosure.
[0075] Oxidation Number of Copper Oxide
[0076] FIG. 3 illustrates a result of thermogravimetric measurement
of copper oxide (II). If the thermogravimetric measurement is
performed for powder of copper oxide (II), an endothermic reaction
is recognized by reduction of copper oxide (II) at a temperature of
1050.degree. C. (refer to DTA of FIG. 3), and decrease of the
weight caused by discharge of oxygen accordingly generated is
observed (refer to TG of FIG. 3). Estimating from the decrease rate
of the weight, it is recognized that the valence of copper oxide
decreases from 2 (before heating) to nearly 1 (after heating). As a
result, it is recognized that copper oxide (II) is reduced by
heating, and the oxidation number decreases, so that copper oxide
containing copper oxide (I) as a main component is generated.
However, in FIG. 3, the valence decreases to 1 (copper oxide (I),
CuO 0.5), and then, re-oxidation is generated, so that the valence
becomes 1.5 (CuO 0.65). Nonetheless, it is estimated that most of
them have a state of copper oxide (I) from the result of X-ray
diffraction described below.
[0077] FIG. 4 illustrates a result of X-ray diffraction measurement
for copper oxide (I) and copper oxide (II). If the X-ray
diffraction is measured before and after heating the powder of
copper oxide (II), a peak belonging to copper oxide (II) is
observed at the room temperature. On the contrary, if it is heated
to 1000.degree. C., the peak belonging to copper oxide (II) is
lost, and only the peak belonging to copper oxide (I) is observed
(FIG. 4). As a result, it is recognized that the valence of copper
oxide (II) decreases by heating so that copper oxide (II) changes
to copper oxide (I).
[0078] Dissolution Selectivity of Copper Oxide
[0079] Hereinafter, description will be made for a result of review
that solubility is changed by the valence of copper oxide when the
copper oxide etchant disclosed herein is used. The number of moles
of copper dissolved when copper oxide (II) powder and copper oxide
(I) powder are input to a glycine aqueous solution of 30 g of 3
mass %, and they are agitated for thirty minutes at a temperature
of 23.degree. C. was obtained. As a result, copper oxide (I) is
dissolved by 0.43 mmol as an equivalent of copper, and copper oxide
(II) is only dissolved by 0.10 mmol as an equivalent of copper.
Therefore, using the copper oxide etchant disclosed herein, it is
possible to selectively dissolve one of the copper oxides when
copper oxides having different valences are mixedly provided.
Example 1
[0080] A film of copper oxide was formed on a glass flat substrate
of 50 mm.phi. using a sputtering method under the following
condition.
[0081] target: copper oxide (II) (3 inches.phi.)
[0082] power (W): RF100
[0083] gas type: mixed gas of argon and oxygen (ratio 95:5)
[0084] pressure (Pa): 0.5
[0085] film thickness (nm): 20
[0086] This copper oxide film was exposed under the following
condition.
[0087] exposure semiconductor laser wavelength: 405 nm
[0088] lens numerical aperture: 0.85
[0089] exposure laser power: 1 mW to 10 mW
[0090] feeding pitch: 260 nm
[0091] Although it is possible to manufacture various shapes or
patterns by modulating the laser light intensity during exposure, a
successive trench shape was used as a pattern in the experiment in
order to facilitate evaluation of an interface after the etching.
The formed shape may be an isolated circular shape, an elliptical
shape, or the like depending on the target use, and the exposure
shape is not intended to limit the disclosure.
[0092] As an index for indicating only the exposure or non-exposure
portions of the copper oxide film are selectively dissolved, if a
ratio of the trench depth after the etching against the original
film thickness is between 0.6 and 1, that is, in this example, the
trench depth is 12 nm to 20 nm against a film thickness of 20 nm,
it can be said that the etching is selectively processed. In
addition, it can be said that particularly excellent selectivity is
obtained if a ratio of the trench depth after the etching against
the original film thickness is between 0.8 and 1. In addition, it
can be said that significantly excellent selectivity is obtained if
the ratio is between 0.9 and 1.
[0093] Next, a copper oxide sample exposed under the aforementioned
condition was etched using the copper oxide etchant prepared under
the following condition. The pH value of the etchant was 6.5, and
the concentration of the chelating agent in the etchant was 3 mass
%.
[0094] glycine: 0.9 g
[0095] water: 30 g
[0096] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 16 minutes at a temperature of
23.degree. C. Then, an atomic force microscope (AFM) image of the
etched copper oxide film was measured. In the AFM measurement, an
atomic force microscope (VN-8000, manufactured by KEYENCE
Corporation) was used. As a result, a periodic trench shape having
a trench depth of 20.0 nm was observed (FIG. 5). For a pitch of 260
nm, the trench width was 88 nm. From this example, it is recognized
that only the copper oxide of which the structure/composition is
changed by thermal reaction through exposure is selectively etched,
and the copper oxide not subjected to the exposure is not
etched.
Example 2
[0097] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 6.4. The concentration of the chelating agent in the
etchant was 3mass %.
[0098] alanine: 0.9 g
[0099] water: 30 g
[0100] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 30 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured (FIG. 6). As a result, the periodic trench shape
having a trench depth of 20.0 nm was observed. For a pitch of 260
nm, the trench width was 80 nm.
Example 3
[0101] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 3.7. The concentration of the chelating agent in the
etchant was 3 mass %.
[0102] ornithine hydrochloride: 0.9 g
[0103] water: 30 g
[0104] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 30 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured (FIG. 7). As a result, the periodic trench shape
having a trench depth of 20.0 nm was observed. For a pitch of 260
nm, the trench width was 85 nm.
Example 4
[0105] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 6.7. The concentration of the chelating agent in the
etchant was 3 mass %.
[0106] lysine: 0.9 g
[0107] water: 30 g
[0108] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 30 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured (FIG. 8). As a result, the periodic trench shape
having a trench depth of 20.0 nm was observed. For a pitch of 260
nm, the trench width was 89 nm.
Example 5
[0109] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 6.5. The concentration of the chelating agent in the
etchant was 3 mass %.
[0110] proline: 0.9 g
[0111] water: 30 g
[0112] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 30 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured (FIG. 9). As a result, the periodic trench shape
having a trench depth of 20.0 nm was observed. For a pitch of 260
nm, the trench width was 82 nm.
Example 6
[0113] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the same condition as that of Example 1. The
etching was performed by spraying the copper oxide etchant to the
copper oxide using a line slit nozzle for 15 minutes at a
temperature of 23.degree. C. Then, the AFM image of the etched
copper oxide film was measured. As a result, the periodic trench
shape having a trench depth of 20.0 nm was observed. For a pitch of
260 nm, the trench width was 98 nm.
Example 7
[0114] The copper oxide film formed under the same condition as
that of Example 1 was exposed under the following condition.
[0115] exposure semiconductor laser wavelength: 405 nm
[0116] lens numerical aperture: 0.85
[0117] exposure laser power: 1 to 10 mW
[0118] feeding pitch: 240 nm.
[0119] Then, the copper oxide sample exposed under the
aforementioned condition was etched using the etchant prepared
under the following condition. The pH value of the etchant was 6.5.
The concentration of the chelating agent in the etchant was 3 mass
%.
[0120] glycine: 0.9 g
[0121] water: 30 g
[0122] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 16 minutes at a temperature of
23.degree. C. Then, an atomic force microscope (AFM) image of the
etched copper oxide film was measured. As a result, a periodic
trench shape having a trench depth of 19.6 nm was observed (FIG.
10). For a pitch of 240 nm, the trench width was 88 nm. From this
example, it is recognized that only the copper oxide of which the
structure/composition is changed by thermal reaction through
exposure is selectively etched, and the copper oxide not subjected
to the exposure is not etched.
Example 8
[0123] The copper oxide film formed and exposed under the same
condition as that of Example 7 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 6.4. The concentration of the chelating agent in the
etchant was 1 mass ft.
[0124] alanine: 0.3 g
[0125] water: 30 g
[0126] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 30 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured. As a result, a periodic trench shape having a trench
depth of 19.8 nm was observed. For a pitch of 260 nm, the trench
width was 107 nm.
Example 9
[0127] The copper oxide film formed and exposed under the same
condition as that of Example 7 was etched using the etchant
prepared under the following condition. The pH value of the etchant
was 6.2. The concentration of the chelating agent in the etchant
was 0.5 mass %.
[0128] methionine: 0.15 g
[0129] water: 30 g
[0130] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 60 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured. As a result, a periodic trench shape having a trench
depth of 20.0 nm was observed. For a pitch of 240 nm, the trench
width was 109 nm.
Example 10
[0131] The copper oxide film formed and exposed under the same
condition as that of Example 7 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 6.7. The concentration of the chelating agent in the
etchant was 0.5 mass %.
[0132] lysine: 0.15 g
[0133] water: 30 g
[0134] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 90 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured. As a result, a periodic trench shape having a trench
depth of 19.9 nm was observed. For a pitch of 240 nm, the trench
width was 115 nm.
Example 11
[0135] The copper oxide film formed and exposed under the same
condition as that of Example 7 was etched using the copper oxide
etchant prepared under the same condition as that of Example 7. The
etching was performed by spraying the etchant to the copper oxide
using a line slit nozzle for 15 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured. As a result, a periodic trench shape having a trench
depth of 20.0 nm was observed. For a pitch of 240 nm, the trench
width was 98 nm.
Example 12
[0136] The copper oxide formed and exposed under the same condition
as that of Example 1 was etched using the copper oxide etchant
prepared under the following condition. In addition, Adekatol
SO-135 is a nonionic surfactant manufactured by ADEKA Corporation.
The pH value of the etchant was 4.6. The concentration of the
chelating agent in the etchant was 0.6 mass %.
[0137] ethylenediaminetetraacetic acid disodium salt: 1.7 g 30%
hydrogen peroxide solution: 1.9 g
[0138] Adekatol SO-135: 0.30 g
[0139] water: 300 g
[0140] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 8 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured. As a result, a periodic trench shape having a trench
depth of 16.5 nm was observed. For a pitch of 260 nm, the trench
width was 100 nm.
Example 13
[0141] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 7.5. The concentration of the chelating agent in the
etchant was 0.5 mass %.
[0142] citric acid trisodium salt: 1.4 g
[0143] 30% hydrogen peroxide solution: 1.9 g
[0144] Adekatol SO-135: 0.40 g
[0145] water: 300 g
[0146] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 30 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured. As a result, a periodic trench shape having a trench
depth of 20.0 nm was observed. For a pitch of 260 nm, the trench
width was 82 nm.
Example 14
[0147] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 6.0. The concentration of the chelating agent in the
etchant was 0.3 mass %.
[0148] glycine: 1.6 g
[0149] 30% hydrogen peroxide solution: 1.9 g
[0150] Adekatol SO-135: 0.40 g
[0151] Water: 300 g
[0152] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 16 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 20.0 nm was observed. For a pitch of 260 nm, the trench
width was 100 nm.
Example 15
[0153] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 4.6. The concentration of the chelating agent in the
etchant was 0.5 mass %.
[0154] citric acid trisodium salt: 1.4 g
[0155] 30% hydrogen peroxide solution: 1.9 g
[0156] Adekatol SO-135: 0.40 g
[0157] water: 300 g
[0158] hydrochloric acid: added until the pH value becomes 4.6.
[0159] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 30 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 20.0 nm was observed. For a pitch of 260 nm, the trench
width was 92 nm.
Example 16
[0160] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 5.3. The concentration of the chelating agent in the
etchant was 0.006 mass %.
[0161] ethylenediaminetetraacetic acid disodium salt: 0.017 g 30%
hydrogen peroxide solution: 1.9 g
[0162] Adekatol SO-135: 0.40 g
[0163] water: 300 g
[0164] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 90 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 15.2 nm was observed. For a pitch of 260 nm, the trench
width was 110 nm.
Example 17
[0165] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 4.0. The concentration of the chelating agent in the
etchant was 5 mass %.
[0166] ethylenediaminetetraacetic acid disodium salt: 17 g
[0167] 30% hydrogen peroxide solution: 1.9 g
[0168] Adekatol SO-135: 0.40 g
[0169] water: 300 g
[0170] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 10 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 13.2 nm was observed. For a pitch of 260 nm, the trench
width was 155 nm.
Example 18
[0171] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 4.5. The concentration of the chelating agent in the
etchant was 0.6 mass %.
[0172] ethylenediaminetetraacetic acid disodium salt: 1.7 g
[0173] 30% hydrogen peroxide solution: 0.10 g
[0174] Adekatol SO-135: 0.40 g
[0175] water: 300 g
[0176] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 60 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 18.5 nm was observed. For a pitch of 260 nm, the trench
width was 97 nm.
Example 19
[0177] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 4.6. The concentration of the chelating agent in the
etchant was 0.6 mass %.
[0178] ethylenediaminetetraacetic acid disodium salt: 1.7 g
[0179] 30% hydrogen peroxide solution: 1.9 g
[0180] Adekatol SO-135: 0.0010 g
[0181] water: 300 g
[0182] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 60 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 16.0 nm was observed. For a pitch of 260 nm, the trench
width was 80 nm.
Example 20
[0183] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 2.5. The concentration of the chelating agent in the
etchant was 0.5 mass %.
[0184] citric acid: 1.4 g
[0185] 30% hydrogen peroxide solution: 1.9 g
[0186] Adekatol SO-135: 0.40 g
[0187] water: 300 g
[0188] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 8 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured (FIG. 11). As a result, a periodic trench shape having a
trench depth of 20.0 nm was observed. For a pitch of 260 nm, the
trench width was 85 nm.
Example 21
[0189] A film was formed and exposed under the same condition as
that of Example 1, and a mixture of the copper oxides having
different valences was etched using the etchant prepared under the
same condition as that of Example 1. The etching was performed by
spraying the etchant to the copper oxide using a line slit nozzle
for 10 minutes at a temperature of 23.degree. C. with a discharge
pressure of 0.03 MPa. Then, the AFM image of the etched copper
oxide was measured. As a result, a periodic trench shape having a
trench depth of 14.2 nm was observed. For a pitch of 260 nm, the
trench width was 142 nm.
Example 22
[0190] A film of copper oxide was formed on an aluminum roll
substrate having a length of 100 mm and 120 mm.phi. using a
sputtering method under the following condition.
[0191] target: copper oxide (II) (3 inches.phi.)
[0192] power (W): RF100
[0193] gas type: mixed gas of argon and oxygen (ratio 9:1)
[0194] pressure (Pa): 0.5
[0195] film thickness (nm): 20
[0196] This copper oxide film was exposed under the following
condition.
[0197] exposure semiconductor laser wavelength: 405 nm
[0198] lens numerical aperture: 0.85
[0199] exposure laser power: 1 mW to 10 mW
[0200] feeding pitch: 260 nm
[0201] Then, exposure was performed, and a mixture of the copper
oxides having different valences was etched using the etchant
prepared under the same condition as that of Example 1. The etching
was performed by spraying the etchant to a mixture of the copper
oxides having different valences using a line slit nozzle for 10
minutes at a temperature of 23.degree. C. with a discharge pressure
of 0.02 MPa. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 14.8 nm was observed. For a pitch of 260 nm, the trench
width was 135 nm.
Example 23
[0202] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 1.7. The concentration of the chelating agent in the
etchant was 0.3 mass %.
[0203] oxalic acid: 0.9 g
[0204] 30% hydrogen peroxide solution: 1.9 g
[0205] Adekatol SO-35: 0.40 g
[0206] water: 300 g
[0207] The etching was performed by immersing the copper oxide in
the copper oxide etchant for one minute at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide film
was measured (FIG. 12). As a result, a periodic trench shape having
a trench depth of 20.0 nm was observed. For a pitch of 260 nm, the
trench width was 100 nm.
Example 24
[0208] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 4.6. The concentration of the chelating agent in the
etchant was 0.3 mass %.
[0209] sodium oxalic acid: 1.0 g
[0210] 30% hydrogen peroxide solution: 1.9 g
[0211] Adekatol SO-135: 0.40 g
[0212] water: 300 g
[0213] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 4 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 20.0 nm was observed. For a pitch of 260 nm, the trench
width was 82 nm.
Example 25
[0214] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 4.6. The concentration of the chelating agent in the
etchant was 0.3 mass %.
[0215] oxalic acid: 0.9 g
[0216] 30% hydrogen peroxide solution: 1.9 g
[0217] Adekatol SO-135: 0.40 g
[0218] water: 300 g
[0219] 10% sodium hydroxide solution: added until the pH value
becomes 4.6
[0220] The etching was performed by immersing the copper oxide in
the copper oxide etchant for 4 minutes at a temperature of
23.degree. C. Then, the AFM image of the etched copper oxide was
measured. As a result, a periodic trench shape having a trench
depth of 19.0 nm was observed. For a pitch of 260 nm, the trench
width was 98 nm.
Example 26
[0221] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the same condition as that of Example 16.
The etching was performed by spraying the etchant to the copper
oxide using a line slit nozzle for 0.5 minutes at a temperature of
23.degree. C. with a discharge pressure of 0.03 MPa. Then, the AFM
image of the etched copper oxide was measured. As a result, a
periodic trench shape having a trench depth of 18.2 nm was
observed. For a pitch of 260 nm, the trench width was 97 nm.
Example 27
[0222] A film of copper oxide was formed on an aluminum roll
substrate having a length of 100 mm and 120 mm.phi. using a
sputtering method under the following condition.
[0223] target: copper oxide (II) (3 inches.phi.)
[0224] power (W): RF100
[0225] gas type: mixed gas of argon and oxygen (ratio 9:1)
[0226] pressure (Pa): 0.5
[0227] film thickness (nm): 20
[0228] This copper oxide film was exposed under the following
condition.
[0229] exposure semiconductor laser wavelength: 405 nm
[0230] lens numerical aperture: 0.85
[0231] exposure laser power: 1 mW to 10 mW
[0232] feeding pitch: 260 nm
[0233] Then, the copper oxide was etched using the copper oxide
etchant prepared under the same condition as that of Example 16.
The etching was performed by spraying the etchant to a mixture of
the copper oxides having different valences using a line slit
nozzle for 0.5 minutes at a temperature of 23.degree. C. with a
discharge pressure of 0.02 MPa. Then, the AFM image of the etched
copper oxide was measured. As a result, a periodic trench shape
having a trench depth of 19.6 nm was observed. For a pitch of 260
nm, the trench width was 96 nm.
Comparative Example 1
[0234] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition.
[0235] sulfuric acid-copper pentahydrate: 6.6 g
[0236] water: 300 g
[0237] ammonia water: added until the pH value becomes 9
[0238] The etching was performed by immersing the copper oxide film
in the etchant for 60 minutes at a temperature of 23.degree. C.,
and the AFM image was measured. However, the trench shape was not
observed. In this etchant, it is not possible to selectively etch
only one of a mixture of the copper oxides having different
oxidation numbers.
Comparative Example 2
[0239] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 6.0. The concentration of the chelating agent in the
etchant was 0.0000003 mass %.
[0240] ethylenediaminetetraacetic acid disodium salt: 0.001 g
[0241] 30% hydrogen peroxide solution: 1900 g
[0242] Adekatol SO-135: 400 g
[0243] water: 300 kg
[0244] The etching was performed by immersing the copper oxide film
in the etchant for 120 minutes at a temperature of 23.degree. C.,
and the AFM image was measured. However, the trench shape was not
observed. In this etchant, it is not possible to selectively etch
only one of a mixture of the copper oxides having different
oxidation numbers.
Comparative Example 3
[0245] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the copper oxide
etchant prepared under the following condition. The pH value of the
etchant was 4.4. The concentration of the chelating agent in the
etchant was 0.5 mass %.
[0246] ethylenediaminetetraacetic acid disodium salt: 1.7 g 30%
hydrogen peroxide solution: 19 g
[0247] Adekatol SO-135: 0.40 g
[0248] water: 300 g
[0249] The etching was performed by immersing the copper oxide film
in the etchant for 5 minutes at a temperature of 23.degree. C., and
as a result, the entire copper oxide film was lost. The AFM image
was measured, but the trench shape was not observed. In this
etchant, it is not possible to selectively etch only one of a
mixture of the copper oxides having different oxidation
numbers.
Comparative Example 4
[0250] The copper oxide film formed and exposed under the same
condition as that of Example 1 was etched using the etchant
prepared under the same condition as that of Example 12.
[0251] The etching was performed by spraying the etchant to a
mixture of the copper oxides having different valences using a line
slit nozzle for 2 minutes at a temperature of 23.degree. C. with a
discharge pressure of 0.3 MPa. Then, the AFM image of the etched
copper oxide was measured. As a result, while a periodic trench
shape having a trench depth of 5.8 nm was observed in a certain
place, no trench shape was found in other places, so that the
etching selectivity or homogeneity was degraded resultantly.
Comparative Example 5
[0252] A film was formed under the same condition as that of
Example 1, exposure was performed, and a mixture of the copper
oxides having different valences was etched using the etchant
prepared under the following condition. The pH value of the etchant
was 5.0. The concentration of the chelating agent in the etchant
was 0.0000003 mass %.
[0253] oxalic acid: 0.00001 g
[0254] 30% hydrogen peroxide solution: 19 g
[0255] Adekatol SO-135: 4.0 g
[0256] water: 3000 g
[0257] The etching was performed by immersing the copper oxide film
in the etchant for 120 minutes at a temperature of 23.degree. C.,
and the AFM image was measured. However, the trench shape was not
observed. In this etchant, it is not possible to selectively etch
only one of a mixture of the copper oxides having different
oxidation numbers.
Comparative Example 6
[0258] A film was formed under the same condition as that of
Example 1, exposure was performed, and a mixture of the copper
oxides having different valences was etched using the etchant
prepared under the following condition. The pH value of the etchant
was 1.6. The concentration of the chelating agent in the etchant
was 0.3 mass %.
[0259] oxalic acid: 0.9 g
[0260] 30% hydrogen peroxide solution: 19 g
[0261] Adekatol SO-135: 0.40 g
[0262] water: 300 g
[0263] The etching was performed by immersing the copper oxide film
in the etchant for one minute at a temperature of 23.degree. C.,
and as a result, the entire copper oxide film was lost. The AFM
image was measured, but the trench shape was not observed. In this
etchant, it is not possible to selectively etch only one of a
mixture of the copper oxides having different oxidation
numbers.
Comparative Example 7
[0264] A film was formed under the same condition as that of
Example 27, exposure was performed, and a mixture of the copper
oxides having different valences was etched using the etchant
adjusted under the same condition as that of Example 23.
[0265] The etching was performed by spraying the etchant to a
mixture of the copper oxides having different valences using a line
slit nozzle for 0.5 minutes at a temperature of 23.degree. C. with
a discharge pressure of 0.3 MPa. Then, the AFM image of the etched
copper oxide was measured. As a result, while a periodic trench
shape having a trench depth of 2.6 nm was observed in a certain
place, no trench shape was found in other places, so that the
etching selectivity or homogeneity was degraded resultantly.
INDUSTRIAL APPLICABILITY
[0266] Using the copper oxide etchant disclosed herein, it is
possible to selectively etch exposure/non-exposure portions when
the copper oxide is used as a thermal-reactive resist, and exposure
is performed using laser light. Therefore, the copper oxide etchant
disclosed herein is effective to manufacture a fine pattern, and
may be applied in various fields such as an optical material.
[0267] This application claims a priority of Japanese Patent
Application Nos. 2010-39693 and 2010-40122, filed Feb. 25, 2010,
Japanese Patent Application No. 2010-154855, filed Jul. 7, 2010,
and Japanese Patent Application No. 2010-282267, filed Dec. 17,
2010, which are herein incorporated by reference.
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