WO2019180915A1

WO2019180915A1 - Etching liquid for thick copper film

Info

Publication number: WO2019180915A1
Application number: PCT/JP2018/011695
Authority: WO
Inventors: 祐二白濱; 真着能
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2018-03-23
Filing date: 2018-03-23
Publication date: 2019-09-26
Also published as: JP6443649B1; TWI678435B; TW201940742A; JPWO2019180915A1; CN109415818A

Abstract

Provided is an etching liquid for a thick copper film, which has a high etching rate such that the same production speed as that achieved with conventional etching liquids can be maintained even when the copper film to be etched is thick, and which allows for etching under high copper ion concentrations. The etching liquid for a thick copper film contains hydrogen peroxide, a strongly acidic substance, an amine compound, a hydrogen peroxide decomposition inhibitor, an azole, and water, and has a pH of less than 2. Even when the copper ion concentration is as high as 20,000 ppm, the etching liquid allows for etching of the copper film at an etching rate of 380 nm/min or higher. Additionally, with this etching liquid, the taper angle can be adjusted to 30º-80º.

Description

Etching solution for copper thick film

The present invention relates to an etching solution for thick copper film used when etching copper used for wiring of flat panel displays such as liquid crystal and organic EL.

Aluminum has been used as a wiring material for TFTs (Thin Film Transistors) of flat panel displays (FPD) such as liquid crystal and organic EL (Electro-Luminescence). In recent years, large-screen, high-definition FPDs have become widespread, and the wiring material used has been required to have a resistance lower than that of aluminum. In recent years, therefore, copper, which has a lower resistance than aluminum, has been used as a wiring material.

The FPD wiring is formed by wet etching a copper film formed by a sputtering method. This is because a large area can be formed at a stretch, and the process can be shortened. Here, the following points are important for wet etching of wiring.
(1) Processing accuracy is high and uniform.
(2) The wiring cross section after processing is a forward taper of a predetermined angle.
(3) The etching rate does not change because copper ions are contained (the bath life is long).

Patent Document 1 is disclosed as an etchant that satisfies such requirements.
here,
Hydrogen peroxide,
An acidic organic acid,
An amine compound;
A hydrogen peroxide decomposition inhibitor;
Azoles,
A multilayer film etching solution containing molybdenum and copper, characterized by containing a precipitation inhibitor containing an aluminum salt, is disclosed.

This etchant has an etching rate of copper (Cu) and molybdenum (Mo), a taper angle of the etched boundary region, an undercut of molybdenum (Mo), a residue of molybdenum (Mo), resistance to overetching, precipitates, It has the performance that satisfies the level used in the production at the present time in the evaluation such as the rate of superhydrolysis.

For the same purpose, Patent Document 2 includes at least one selected from (A) hydrogen peroxide, (B) an inorganic acid not containing a fluorine atom, (C) succinic acid, glycolic acid, lactic acid, malonic acid, and malic acid. A kind of organic acid, (D) an amine compound having 2 to 10 carbon atoms and having an amino group and a hydroxyl group so that the total number of groups is 2 or more, (E) 5-amino-1H-tetrazole, and (F) A multilayer thin film etching solution containing a hydrogen peroxide stabilizer and a copper layer and a molybdenum layer having a pH of 2.5 to 5 is disclosed.

Japanese Patent Application Laid-Open No. 2015-209568 Japanese Patent No. 5051323

Currently, high-resolution standards such as 4K and 8K have been proposed. These standards do not work on small screens. Therefore, a display (large screen FPD) having a larger screen than before has been developed. In the large screen FPD, since the distance of the wiring for driving the pixel becomes long, a wiring with lower resistance is required. In order to reduce the resistance in the copper wiring, it is conceivable to increase the cross-sectional area of the wiring. However, if the width of the wiring is increased and the area of one pixel is increased, the demand for high definition cannot be satisfied.

On the other hand, in order to lower the resistance of the wiring material, it is possible to use a material having a lower resistivity than copper, such as silver or gold, but the cost becomes too high, which is not desirable from the viewpoint of diffusion. As a result, it is necessary to increase the cross-sectional area and increase the resistance value by increasing the thickness direction of the copper wiring.

In order to form a wiring with thick copper, it is necessary to solve the following technical problems.
(1) In order to maintain the same manufacturing rate as before, the etching rate is increased.
(2) Since the amount of etched copper ions increases in the etching solution, etching can be performed even at a high copper ion concentration.

The present invention has been conceived in order to solve the above problems, and provides an etching solution for a copper thick film that has a high etching rate and can be etched even under a high copper ion concentration.

More specifically, the etching solution for copper thick film according to the present invention is:
Hydrogen peroxide,
Strongly acidic substances,
An amine compound;
A hydrogen peroxide decomposition inhibitor;
Azoles,
Including water,
pH is less than 2.

The copper thick film etching solution according to the present invention has an etching rate of 380 nm / min or more as an etching rate. Further, even if the copper ion concentration is 20,000 ppm, the etching can be continued.

Accordingly, the copper thick film etching solution according to the present invention can be processed in a conventional process time when etching copper in a thick film state, and a high concentration of copper ions is contained in the etching solution. Even if it remains, the etching can be continued.

It is a conceptual diagram showing the cross section of the etched wiring.

Hereinafter, the copper thick film etching solution according to the present invention will be described. The following description shows an embodiment of the etching solution according to the present invention, and the following embodiments and examples may be modified without departing from the spirit of the present invention. In the following description, when the numerical range is indicated by “A to B” or “A to B”, it means “A or more and B or less”. That is, it means a large range including the numerical value A and a small range including the numerical value B. Further, “greater than A” means large without including the numerical value A, and “less than A” means small without including the numerical value A.

The copper thick film etching solution according to the present invention contains hydrogen peroxide, a strongly acidic substance, an amine compound, a hydrogen peroxide decomposition inhibitor, an azole, and water, and has a pH of less than 2. Hereinafter, each component will be described in detail.

<Hydrogen peroxide>
In the etching of copper, copper is oxidized to become copper oxide (CuO) and is dissolved by an acid. That is, hydrogen peroxide is used as an oxidizing agent that oxidizes copper. Hydrogen peroxide and overwater are synonymous. Hydrogen peroxide is preferably 4.0% by mass to 5.8% by mass with respect to the total amount of the etching solution.

<Strongly acidic substances>
The copper thick film etching solution according to the present invention has a pH of less than 2 in order to increase the etching rate. Therefore, it is necessary to use a strongly acidic substance. The strongly acidic substance may be an inorganic strong acid or an organic strong acid. Moreover, even if it is weakly acidic, it is sufficient if the pH of the entire etching solution can be made less than 2.

Generally, the strength of an acid is represented by an acid dissociation constant Ka. A value obtained by taking the negative logarithm of the acid dissociation constant Ka is referred to as pKa. Strongly acidic substances that can be used in the present invention include those having a pKa of 3 or less in addition to a substance called a strong acid having a pKa of 0 or less. This is because a plurality of types of substances are mixed in the etching solution, but if the pKa is 3 or less, the pH of the entire etching solution can be adjusted to less than 2. Therefore, the strongly acidic substance in the present invention is a substance having a pKa of 3 or less.

Specifically, examples of the strongly acidic substance inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, hydrobromic acid (hydrogen bromide aqueous solution), hydroiodic acid (hydrogen iodide aqueous solution), sulfamic acid, and the like.

In addition, organic acids that are strongly acidic substances include glycine, asparagine, aspartic acid, alanine, glutamic acid, valine, glutamine, glutamic acid, leucine, arginine, isoleucine, lysine, serine, histidine, threonine, phenylalanine, cysteine, tyrosine, methionine, Amino acids such as tryptophan, proline, malonic acid, pyruvic acid, oxalic acid, tartaric acid, trans-aconitic acid, p-toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, vinylsulfonic acid, picric acid, trichloroacetic acid, Compounds such as acetamide, salicylic acid and 4-nitroaniline can be suitably used.

In addition, what has a halogen in a skeleton is mentioned as what shows strong acidity with an organic acid. There are particularly strongly acidic substances such as trifluoroacetic acid. However, those containing fluorine in the skeleton may be converted into hydrofluoric acid and may damage the substrate, so it is desirable to remove them from the strongly acidic substance according to the present invention.

The strongly acidic substance can be contained in an amount of 5% by mass to 15% by mass with respect to the total amount of the etching solution. In order to adjust the portion to be etched and the taper angle after etching, a chemical described later may be prepared so that the total pH is less than 2.

<Organic acid>
The copper thick film etching solution according to the present invention may contain a weakly acidic organic acid in addition to the strongly acidic substance in order to adjust the taper angle and suppress the decomposition of hydrogen peroxide. Here, weak acid means a substance having an acid dissociation constant pKa larger than 3.

Specifically, preferred examples of the organic acid include aliphatic carboxylic acids having 1 to 18 carbon atoms, aromatic carboxylic acids having 6 to 10 carbon atoms, and amino acids having 1 to 10 carbon atoms.

Examples of aliphatic carboxylic acids having 1 to 18 carbon atoms include formic acid, acetic acid, propionic acid, lactic acid, glycolic acid, diglycolic acid, butyric acid, hydroxybutyric acid, succinic acid, malic acid, maleic acid, fumaric acid, valeric acid, and glutar Preferred are acid, itaconic acid, adipic acid, caproic acid, citric acid, propanetricarboxylic acid, enanthic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and the like.

Preferred examples of the aromatic carboxylic acid having 6 to 10 carbon atoms include benzoic acid, mandelic acid, phthalic acid, isophthalic acid, and terephthalic acid.

Preferred examples of the amino acid having 1 to 10 carbon atoms include carbamic acid, sarcosine, 4-aminobutyric acid, iminodibutyric acid, nitrilotriacetic acid and the like. The weakly acidic organic acid can be contained in an amount of 1 to 20% by mass with respect to the total amount of the etching solution.

<Amine compound>
The amine compound is responsible for adjusting the taper angle of the copper film and adjusting the pH of the etching solution. As the amine compound, those having 2 to 10 carbon atoms can be suitably used. More specifically, ethylenediamine, trimethylenediamine, tetramethylenediamine, 1,2-propanediamine, 1,3-propanediamine, N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1 , 3-propanediamine, 1,3-diaminobutane, 2,3-diaminobutane, pentamethylenediamine, 2,4-diaminopentane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, N-methyl Ethylenediamine, N, N-dimethylethylenediamine, trimethylethylenediamine, N-ethylethylenediamine, N, N-diethylethylenediamine, triethylethylenediamine, 1,2,3-triaminopropane, hydrazine, tris (2-aminoethyl) amino , Tetra (aminomethyl) methane, diethylenetriamine, triethylenetetramine, tetraethylpentamine, heptaethyleneoctamine, nonaethylenedecamine, diazabicycloundecene, etc .; ethanolamine, N-methylethanolamine, N-methyldiethanolamine N-ethylethanolamine, N-aminoethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, triethanolamine, 1-amino-2-propanol, N-methylisopropanolamine, N-ethylisopropanol Amine, triisopropanolamine, diisopropanolamine, N-propylisopropanolamine, 2-aminopropan-1-ol, N-methyl-2 Amino-propan-1-ol, N-ethyl-2-amino-propan-1-ol, 1-aminopropane-3-ol, N-methyl-1-aminopropane-3-ol, N-ethyl-1- Aminopropan-3-ol, 1-aminobutan-2-ol, N-methyl-1-aminobutan-2-ol, N-ethyl-1-aminobutane-2-ol, 2-aminobutan-1-ol, N-methyl- 2-aminobutan-1-ol, N-ethyl-2-aminobutan-1-ol, 3-aminobutane-1-ol, N-methyl-3-aminobutan-1-ol, N-ethyl-3-aminobutane-1- All, 1-aminobutane-4-ol, N-methyl 1-aminobutane-4-ol, N-ethyl-1-aminobutane-4-ol, 1-amino-2-me Tilpropan-2-ol, 2-amino-2-methylpropan-1-ol, 1-aminopentan-4-ol, 2-amino-4-methylpentan-1-ol, 2-aminohexane-1-ol, 3-aminoheptan-4-ol, 1-aminooctane-2-ol, 5-aminooctane-4-ol, 1-aminopropane-2,3-diol, 2-aminopropane-1,3-diol, tris (Oxymethyl) aminomethane, 1,2-diaminopropan-3-ol, 1,3-diaminopropan-2-ol, 2- (2-aminoethoxy) ethanol, 2- (2-aminoethylamino) ethanol, Preferred examples include alkanolamines such as diglycolamine, and these can be used alone or in combination.

Among these, 1-amino-2-propanol (CAS number 78-96-6: hereinafter also referred to as “1A2P”), N, N-diethyl-1,3-propanediamine (CAS number 104-78-9: (Hereinafter also referred to as “NNDPA”), triisopropanolamine (CAS number 122-20-3: hereinafter also referred to as “TIPA”) and diisopropanolamine (CAS number 110-97-4: hereinafter also referred to as “DIPA”) Is particularly preferred. Further, the amine compound is preferably contained in an amount of 0.05% to 5.5% by mass with respect to the total amount of the etching solution.

<Hydrogen peroxide decomposition inhibitor>
In the copper thick film etching solution according to the present invention, hydrogen peroxide is used as an oxidizing agent. Since hydrogen peroxide self-decomposes, a decomposition inhibitor that suppresses the decomposition is added. The hydrogen peroxide decomposition inhibitor is also referred to as a hydrogen peroxide stabilizer (or “super water stabilizer”).

Examples of the hydrogen peroxide decomposition inhibitor include urea-based hydrogen peroxide decomposition inhibitors such as urea, phenylurea, allylurea, 1,3-dimethylurea, thiourea, phenylacetamide, phenylethylene glycol, 1- Lower alcohols such as propanol and 2-propanol, ethylene glycol monobutyl ether, and the like can be used. Among these, urea (CAS No. 57-13-6), phenylurea (CAS No. 64-10-8: hereinafter also referred to as “FN”), 1-propanol (CAS No. 71-23-8: hereinafter referred to as “1P”). And ethylene glycol monobutyl ether (CAS No. 111-76-2: hereinafter also referred to as “BG”) is particularly preferred. The hydrogen peroxide decomposition inhibitor is preferably contained in an amount of 0.1% by mass to 2.0% by mass with respect to the total amount of the etching solution.

<Azoles>
The copper thick film etching solution according to the present invention contains azoles in order to suppress the etching rate of Cu. In the copper thick film etching solution according to the present invention, the pH is set to less than 2 in order to increase the etching rate. In this pH region, the etching rate changes sharply due to a slight pH difference. Then, the etching rate may not be adjusted only by the composition ratio of the strongly acidic substance. Therefore, an etching rate inhibitor is used.

As the azoles, triazoles, tetrazoles, imidazoles, thiazoles and the like can be suitably used. More specifically, the following can be listed. As the triazole, 1H-benzotriazole, 5-methyl-1H-benzotriazole, 3-amino-1H-triazole and the like can be preferably used.

As the tetrazole, 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole and the like can be suitably used. As imidazoles, 1H-imidazole, 1H-benzimidazole and the like can be preferably used. As thiazoles, 1,3-thiazole, 4-methylthiazole and the like can be suitably used.

Of these, tetrazoles are highly effective in suppressing the etching rate, and in particular, 5-amino-1H-tetrazole (CAS number 4418-61-5: hereinafter also referred to as “5A1HT”), 5-methyl-1H-tetrazole. (CAS number 4076-36-2: hereinafter also referred to as “5M1HT”), 5-phenyl-1H-tetrazole (CAS number 18039-42-4: hereinafter also referred to as “5phenyl1HT”) is preferred, and triazoles are preferred. 5-methyl-1H-benzotriazole (CAS number 136-85-6: hereinafter also referred to as “5M1HBTA”) and 1H-benzotriazole (CAS number 95-14-7: hereinafter also referred to as “BTA”) are preferable. .

These azoles are preferably contained in an amount of 0.01% by mass to 0.10% by mass with respect to the total amount of the etching solution.

<Copper ion>
An etching solution for dilution is usually added to the copper etching solution so that the Cu ion concentration is about 2,000 ppm to 4,000 ppm. This is because when the copper ion concentration is increased, the decomposition rate of the excess water is increased, and thus the excess water concentration in the etching solution is decreased. However, the etching solution according to the present invention uses the hydrogen peroxide decomposition inhibitor in an environment with strong acidity, and therefore suppresses the decomposition rate of overwater. Therefore, it is not necessary to add an etching solution for diluting Cu ions even when the Cu ion concentration is higher. More specifically, it is not necessary to add an etching solution for dilution until the Cu concentration of the etching solution is 20,000 ppm.

<Others>
In addition to these components, the copper thick film etching solution of the present invention may contain water and various commonly used additives as long as the etching performance is not impaired. Since water is used for precision processing, it is preferable that water does not exist. Pure water or ultrapure water is preferable. Water can be determined as the remaining component for each of the above components.

Further, it goes without saying that the range of the content ratio of each component described above is appropriately adjusted so that the total amount of the etching solution becomes 100% by mass. Moreover, although copper ion may be contained from the beginning, since the amount is small relative to other compositions, the composition ratio as the total amount of the etching solution is ignored.

<PH, temperature>
The copper thick film etching solution according to the present invention is adjusted to a pH of less than 2. The etching solution can be used between 20 ° C. and 40 ° C. More preferably, it is 25 degreeC to 35 degreeC, Most preferably, 30 degreeC to 35 degreeC is good.

<Save>
Hydrogen peroxide is used in the copper thick film etching solution according to the present invention. Hydrogen peroxide is self-degrading. Therefore, the etchant contains a hydrogen peroxide decomposition inhibitor. However, when storing, hydrogen peroxide (or hydrogen peroxide solution) and other liquids may be stored separately. The hydrogen peroxide solution is an aqueous solution of hydrogen peroxide. Further, only hydrogen peroxide (or hydrogen peroxide solution), raw materials excluding water and copper ions (referred to as “etching solution raw material”) may be stored together. In addition, the thing of a liquid and a powder may exist in an etching liquid raw material. That is, the copper thick film etching solution according to the present invention may be completed by combining the etching solution raw material, water, and hydrogen peroxide (or hydrogen peroxide solution).

Also, an etchant raw material solution may be prepared by mixing an etchant raw material and water. A solution of the etchant raw material prepared with the etchant raw material and water is referred to as an “etching concentrate”. The etching concentrate has a smaller volume as compared with the etching liquid because there is no hydrogen peroxide, so it is convenient for storage and transport. Therefore, the copper thick film etching solution of the present invention may be completed by combining the etching concentrate, water, and hydrogen peroxide.

Here, the amount of water in the etching concentrate may be sufficient to dissolve the etching solution raw material. In other words, the water in the etching concentrate may be less than the water in the etching liquid. Accordingly, when it is considered that hydrogen peroxide is supplied as an aqueous hydrogen peroxide solution, the copper thick film etching solution of the present invention is completed by combining the etching concentrated solution, water, and hydrogen peroxide solution. be able to.

Also, if water is included in the etching concentrate or hydrogen peroxide solution, it can be completed by combining the etching concentrate and hydrogen peroxide solution. Moreover, in this specification, each component ratio of an etching concentrate is represented by the ratio with respect to the whole quantity when an etching liquid is completed. Therefore, the total of the components of the etching concentrate is not 100% by mass.

<Etching method>
The object using the copper thick film etching solution according to the present invention is a copper film formed on a substrate with a thickness of 600 nm or more. An isolation layer made of another element may be formed between the substrate and the copper film. The etching method according to the present invention is performed by bringing a substrate on which a copper film is formed to a thickness of 600 nm or more into contact with an etching solution for copper thick film.

The copper thick film etching solution according to the present invention can be stored for a long period of time by storing hydrogen peroxide, the etching solution raw material (or etching concentrate) and water separately during storage. Therefore, in actual use, these are mixed to complete the etching solution. The blending method is not limited as long as the concentration of hydrogen peroxide finally reaches a predetermined concentration.

As an example, an etching concentrate is prepared by mixing a raw material for etching with a certain amount of water. Hydrogen peroxide is normally supplied as a hydrogen peroxide solution having a concentration higher than the hydrogen peroxide concentration of the copper thick film etching solution according to the present invention. Therefore, a predetermined amount of hydrogen peroxide solution and etching concentrate is prepared. This step may be called a step of preparing an etching solution for copper thick film. In the prepared etching solution for thick copper film, each component is prepared at a predetermined ratio, and the pH is less than 2.

When etching is performed, as described above, the etching solution is used under the condition of less than pH 2 and 20 ° C. to 40 ° C. Therefore, it is desirable that the object to be etched is also preheated to this temperature. The method for bringing the substrate to be processed into contact with the etching solution is not particularly limited. An etching solution may be sprayed on the substrate to be processed from above as in a shower type, or a method of dipping the substrate to be processed into a pool of etching solution may be used. This may be called a step of bringing the copper thick film etching solution into contact with the substrate to be processed.

The substrate to be processed is a substrate in a state where at least a copper film is formed on a base material such as glass and a resist pattern for pattern formation is formed on the copper film.

<Description of various evaluation methods>
The copper thick film etchant according to the present invention was evaluated in terms of the copper etching rate (nm / min), the taper angle (°) of the cross section of the etched wiring, and the shape after etching.

The etching rate was measured as follows. First, a copper film having a thickness of 600 nm was formed by sputtering on a silicon wafer on which a thermal oxide film of 100 nm was formed. This copper film was brought into contact with an etching solution at 30 ° C. (may be 35 ° C. in some comparative examples) for 20 to 60 seconds.

The resistance value of the film before and after etching was measured using a constant current application type 4-terminal 4-probe resistivity meter (manufactured by Mitsubishi Chemical Analytech: MCP-T610 type). The change in film thickness was calculated from the change in resistance value, and the etching rate was calculated.

In addition, if the etching rate of copper was 380 nm / min or more, it was judged as a circle (◯). Other than that, it was judged as X (outside) as outside the specified range.

"Maru" means within the standard range, success or success, and "X" means out of standard range, failure or failure. The same applies to the following evaluations.

The taper angle was measured as follows. First, a copper film with a thickness of 600 nm was formed on a glass substrate by sputtering to produce a copper thick film sample. A resist patterned into a wiring shape was formed on this copper film, and used as a base material for taper angle evaluation. That is, the base material includes a substrate, a copper film, and a patterned resist layer on the copper film. Etching was performed by immersing the base material in an etching solution for the time of just etching. After the etching sample was washed and dried, the wiring portion was cut and the cut surface was observed.

The observation of the cut surface was performed using SEM (Hitachi: SU8020 type) under the conditions of an acceleration voltage of 1 kV and 30,000 to 50,000 times. The shape of the etched portion was also observed during the SEM observation. Note that just etching is the time from the start of etching until the film transmits light. The time when the film transmitted light was visually confirmed.

Schematic diagram of cut surface shape is shown in FIG. As shown in FIG. 1, an angle 3 formed by the substrate 1 and the etched inclined surface 5 is a taper angle (°). If the taper angle 3 was 30 ° to 80 °, it was judged as a circle (◯). If it was out of the range of this angle, it was judged as X (x). In FIG. 1, the Cu layer is represented by reference numeral 2 and the resist is represented by reference numeral 4.

(Example 1)
As a strongly acidic substance,
8.33% by mass of nitric acid
As an amine compound,
5.24% by mass of NNDPA (N, N-diethyl-1,3-propanediamine)
As a water stabilizer,
0.12% by mass of FN (phenylurea)
As azoles,
0.01% by mass of 5M1HT (5-methyl-1H-tetrazole)
An etching solution raw material consisting of 72.41% by mass of water was prepared to prepare an etching concentrate. Each component ratio in the etching concentrate is expressed as a ratio to the total amount when the etching liquid is completed by mixing with a hydrogen peroxide solution described later. The same applies to the following examples and comparative examples.

35% hydrogen peroxide solution 13.89% by mass (hydrogen peroxide 4.86% by mass and moisture 9.03% by mass with respect to the total amount of the etchant) and the etching concentrate were mixed, and the hydrogen peroxide concentration was 4.86 mass% etching liquid was prepared. The total amount of water is 81.44% by mass. Further, copper powder was added to adjust the copper ion concentration to 20,000 ppm. The liquid temperature was 35 ° C. Table 1 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Example 2)
As a strongly acidic substance,
9.88% by mass of malonic acid,
As an amine compound,
1.35% by mass of 1A2P (1-amino-2-propanol)
As a water stabilizer,
0.68% by mass of 1P (1-propanol),
As azoles,
0.05% by mass of 5A1HT (5-amino-1H-tetrazole)
The etching liquid raw material which consists of was mixed with 75.70 mass% of water, and the etching concentrated liquid was prepared.

35% hydrogen peroxide solution 12.34% by weight (4.32% by mass of hydrogen peroxide and 8.02% by mass of water with respect to the total amount of the etching solution) and the etching concentrate were mixed, and the hydrogen peroxide concentration was An etching solution of 4.32% by mass was prepared. The total amount of water is 83.72% by mass. Further, copper powder was added to adjust the copper ion concentration to 20,000 ppm. The liquid temperature was 35 ° C. Table 1 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Example 3)
As a strongly acidic substance,
6.93% by mass of sulfuric acid
1.84% by mass of glycine
As an amine compound,
2.49% by mass of TIPA (triisopropanolamine)
As a water stabilizer,
0.64% by mass of urea
As azoles,
0.03% by mass of 5M1HBTA (5-methyl-1H-benzotriazole)
The etching liquid raw material which consists of with 73.36 mass% of water was prepared, and the etching concentrated liquid was prepared.

35% hydrogen peroxide solution 14.71% by weight (hydrogen peroxide is 5.15% by mass and moisture is 9.56% by mass with respect to the total amount of the etching solution) and the etching concentrate are mixed, and the hydrogen peroxide concentration is An etching solution of 5.15% by mass was prepared. The total amount of water is 82.92% by mass. Further, copper powder was added to adjust the copper ion concentration to 20,000 ppm. The liquid temperature was 35 ° C. Table 1 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

Example 4
As a strongly acidic substance,
7.20% by mass of malonic acid,
6.77% by mass of glutaric acid as organic acid
As an amine compound,
0.06% by mass of DIPA (diisopropanolamine)
As a water stabilizer,
0.96% by mass of BG (ethylene glycol monobutyl ether),
As azoles,
0.03% by mass of 5-phenyl 1HT (5-phenyl-1H-tetrazole)
An etching solution raw material consisting of 70.32% by mass of water was prepared to prepare an etching concentrate.

35% hydrogen peroxide solution 14.66% by weight (5.13% by weight of hydrogen peroxide and 9.53% by weight of water with respect to the total amount of the etching solution) and the etching concentrate were mixed, and the hydrogen peroxide concentration was An etching solution of 5.13% by mass was prepared. The total amount of water is 79.85% by mass. Further, copper powder was added to adjust the copper ion concentration to 20,000 ppm. The liquid temperature was 35 ° C. Table 1 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Example 5)
As a strongly acidic substance,
7.04% by mass of ethanesulfonic acid
Malic acid as organic acid is 4.4% by mass
As an amine compound,
1.04% by mass of TIPA (triisopropanolamine)
As a water stabilizer,
0.85% by mass of BG (ethylene glycol monobutyl ether),
As azoles,
0.02% by mass of BTA (benzotriazole)
The etching liquid raw material which consists of with 71.56 mass% of water was prepared, and the etching concentrated liquid was prepared.

35% hydrogen peroxide solution 15.09% by weight (hydrogen peroxide 5.28% by mass and moisture 9.81% by mass with respect to the total amount of the etching solution) and the etching concentrate were mixed, and the hydrogen peroxide concentration was 5.28 mass% etching liquid was prepared. The total amount of water is 81.37% by mass. Further, copper powder was added to adjust the copper ion concentration to 20,000 ppm. The liquid temperature was 35 ° C. Table 1 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Example 6)
As a strongly acidic substance,
7.04% by mass of ethanesulfonic acid
As an amine compound,
1.04% by mass of TIPA (triisopropanolamine)
As a water stabilizer,
0.85% by mass of BG (ethylene glycol monobutyl ether),
As azoles,
0.02% by mass of BTA (benzotriazole)
The etching liquid raw material which consists of was mixed with 75.96 mass% of water, and the etching concentrated liquid was prepared.

35% hydrogen peroxide solution 15.09% by weight (hydrogen peroxide 5.28% by mass and moisture 9.81% by mass with respect to the total amount of the etching solution) and the etching concentrate were mixed, and the hydrogen peroxide concentration was 5.28 mass% etching liquid was prepared. The total amount of water is 85.77% by mass. Further, copper powder was added to adjust the copper ion concentration to 20,000 ppm. The liquid temperature was 35 ° C. Table 1 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Comparative Example 1)
As a strongly acidic substance,
10.00 mass% nitric acid
As an amine compound,
12.50% by mass of NNDPA (N, N-diethyl-1,3-propanediamine)
As a water stabilizer,
0.10% by mass of FN (phenyl urea)
As azoles,
0.10% by mass of 5M1HT (5-methyl-1H-tetrazole)
An etching liquid raw material consisting of 65.87% by mass of water was prepared to prepare an etching concentrated liquid.

35% hydrogen peroxide solution 11.43% by weight (hydrogen peroxide is 4.00% by mass and moisture is 7.43% by mass with respect to the total amount of the etching solution) and the etching concentrate are mixed, and the hydrogen peroxide concentration is An etching solution of 4.00% by mass was prepared. The total amount of water is 73.30% by mass. Furthermore, although it tried to melt | dissolve so that copper powder might be added and a copper ion density | concentration might be set to 20,000 ppm, it was not able to melt | dissolve. The liquid temperature was 35 ° C. Table 2 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Comparative Example 2)
As a strongly acidic substance,
Ethanesulfonic acid 6.00% by mass
As an amine compound,
9.70% by mass of TIPA (triisopropanolamine)
As a water stabilizer,
BG (ethylene glycol monobutyl ether) 0.70% by mass
As azoles,
0.02% by mass of BTA (benzotriazole)
The etching liquid raw material which consists of with 68.49 mass% of water was prepared, and the etching concentrated liquid was prepared.

35% hydrogen peroxide solution 15.09% by weight (hydrogen peroxide 5.28% by mass and moisture 9.81% by mass with respect to the total amount of the etching solution) and the etching concentrate were mixed, and the hydrogen peroxide concentration was 5.28 mass% etching liquid was prepared. The total amount of water is 78.30% by mass. Furthermore, although it tried to melt | dissolve so that copper powder might be added and a copper ion density | concentration might be set to 20,000 ppm, it was not able to melt | dissolve. The liquid temperature was 35 ° C. Table 2 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Comparative Example 3)
As a strongly acidic substance,
15.80% by mass of malonic acid
As an amine compound,
8.40% by mass of 1A2P (1-amino-2-propanol)
As a water stabilizer,
0.60% by mass of 1P (1-propanol)
As azoles,
0.05% by mass of 5A1HT (5-amino-1H-tetrazole)
An etching liquid raw material consisting of 62.86% by mass of water was prepared to prepare an etching concentrated liquid.

35% hydrogen peroxide solution 12.29% by weight (hydrogen peroxide is 4.30% by mass and moisture is 7.99% by mass with respect to the total amount of etching solution) and the etching concentrate are mixed, and the hydrogen peroxide concentration is 4. 30 mass% etching liquid was prepared. The total amount of water is 70.85% by mass. Further, copper powder was added and dissolved so that the copper ion concentration became 1,000 ppm. The liquid temperature was 35 ° C. Table 2 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Comparative Example 4)
As a strongly acidic substance,
6.90 mass% nitric acid
As an amine compound,
8.34% by mass of NNDPA (N, N-diethyl-1,3-propanediamine)
As a water stabilizer,
0.10% by mass of FN (phenyl urea)
As azoles,
0.10% by mass of 5M1HT (5-methyl-1H-tetrazole)
The etching liquid raw material which consists of was mixed with 71.99 mass% of water, and the etching concentrated liquid was prepared.

35% hydrogen peroxide solution 12.57% by weight (hydrogen peroxide is 4.40% by mass and moisture is 8.17% by mass with respect to the total amount of the etching solution) and the etching concentrate are mixed, and the hydrogen peroxide concentration is 4. An etching solution of 40% by mass was prepared. The total amount of water is 80.16% by mass. Furthermore, although copper powder was added and it tried to melt | dissolve so that copper ion concentration might be set to 1,000 ppm, it was not able to melt | dissolve completely. The liquid temperature was 35 ° C. Table 2 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

(Comparative Example 5)
As a strongly acidic substance,
Ethanesulfonic acid 6.00% by mass
As an amine compound,
5.96% by mass of TIPA (triisopropanolamine)
As a water stabilizer,
0.82% by mass of BG (ethylene glycol monobutyl ether)
As azoles,
0.04% by mass of BTA (benzotriazole)
The etching liquid raw material which consists of with 72.09 mass% of water was prepared, and the etching concentrated liquid was prepared.

35% hydrogen peroxide solution 15.09% by weight (hydrogen peroxide 5.28% by mass and moisture 9.81% by mass with respect to the total amount of the etching solution) and the etching concentrate were mixed, and the hydrogen peroxide concentration was 5.28 mass% etching liquid was prepared. The total amount of water is 81.90% by mass. Furthermore, although copper powder was added and it tried to melt | dissolve so that copper ion concentration might be set to 1,000 ppm, it was not able to melt | dissolve completely. The liquid temperature was 35 ° C. Table 2 shows the concentration of each component in the entire etching solution and the result of each evaluation item.

Referring to Table 1, even when an inorganic acid and an organic acid are used, the pH of the entire etching solution can be adjusted to less than 2 if it is a strongly acidic substance. In addition, the copper thick film etching solution thus prepared can realize an etching rate of 380 nm / min or more under a copper ion environment of 20,000 ppm. The taper angle can be adjusted from 30 ° to 80 °. Also, there was no particular problem with its shape.

Meanwhile, refer to Table 2. The materials used were the same as those shown in Table 1. However, unless the pH of the entire etching solution was set to less than 2, the ion concentration could not be as high as 20,000 ppm. Etching was not possible because copper ions could not be dissolved.

Further, when the strongly acidic substance is composed only of an organic acid, the amine compound is preferably 0.05% by mass or more and less than 2.0% by mass (Examples 2, 4, 5, 6). reference). It is considered that the strongly acidic substance of the organic acid has a higher pKa than that of the inorganic acid, so that if the amine compound is added too much, the pH of the entire etching solution cannot be made less than 2.

As described above, the etching solution for thick copper film according to the present invention can realize a high etching rate even under a high copper ion concentration, and etch thick film copper on a large area substrate at a processing speed of an actual mass production machine. can do.

The etching solution according to the present invention can be suitably used when etching a thick copper film of 600 nm or more.

1 substrate 2 Cu layer 3 taper angle 4 resist 5 inclined surface

Claims

Hydrogen peroxide,
Strongly acidic substances,
An amine compound;
A hydrogen peroxide decomposition inhibitor;
Azoles,
Including water,
Etching solution for copper thick film whose pH is less than 2.
The copper thick film etching solution according to claim 1, further comprising a weakly acidic organic acid.
The azole is one or more selected from 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-methyl-1H-benzotriazole, and benzotriazole. The copper thick film etching solution according to claim 1 or 2.
4. The amine compound according to claim 1, wherein the amine compound is one or more selected from 1-amino-2-propanol, N, N-diethyl-1,3-propanediamine, triisopropanolamine, and diisopropanolamine. Etching solution for copper thick film according to any one of claims.
The copper according to any one of claims 1 to 4, wherein the hydrogen peroxide decomposition inhibitor is one or more selected from urea, phenylurea, 1-propanol, and ethylene glycol monobutyl ether. Thick film etchant.
Strongly acidic substances,
An amine compound;
A hydrogen peroxide decomposition inhibitor;
Azoles,
An etching concentrate for copper thick film containing water and free of hydrogen peroxide,
Etching concentrate for copper thick film that has a pH of less than 2 by adding hydrogen peroxide so that the total amount is 4.0 to 5.8% by mass.
The copper concentrate thick film etching concentrate according to claim 6, further comprising a weakly acidic organic acid.
Strongly acidic substances,
An amine compound;
A hydrogen peroxide decomposition inhibitor;
Azoles,
Including water,
Hydrogen peroxide is added so that the pH becomes less than 2 by adding hydrogen peroxide so that the total amount is 4.0% to 5.8% by mass. To prepare an etching solution for copper thick film in addition to 5.8% by mass from
A method for etching a copper thick film, comprising a step of bringing a substrate on which a copper film has a thickness of 600 nm or more into contact with the copper thick film etching solution.