CN118223024A - Etching solution for copper thick film - Google Patents

Abstract

Providing: the etching solution for copper thick film has a high etching rate and can be etched even at a high copper ion concentration to thicken the copper film thickness so that the conventional production rate can be maintained. The etching solution for copper thick films, which comprises 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, can etch a copper film at an etching rate of 380 nm/min or more even at a high copper ion concentration of 20000ppm, and further can adjust the taper angle to 30 DEG to 80 deg.

Description

Etching solution for thick copper film

This application is a divisional application of an application with a filing date of March 23, 2018, an application number of 201880002496.2, and an invention name of “Etching liquid for copper thick film”.

Technical Field

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

Background technique

Aluminum is used as a wiring material for TFT (Thin Film Transistor) of flat panel displays (FPD) such as liquid crystal and organic EL (Electro-Luminescence). In recent years, large-screen and high-definition FPDs have become popular, and the wiring materials used are required to have lower resistance than aluminum. Therefore, copper, which has lower resistance than aluminum, has gradually been used as a wiring material in recent years.

The wiring of FPD is formed by wet etching a copper film formed by sputtering. This is because a large area can be formed at one time, which can shorten the process. Here, the following points are important in wet etching of wiring.

(1) High processing precision and uniformity.

(2) The cross section of the wiring after processing is a positive taper with a specified angle.

(3) The etching rate does not change due to the inclusion of copper ions (the bath plating life is long).

Patent Document 1 discloses an etching solution that meets such a requirement.

Here, an etching solution for a multilayer film containing molybdenum and copper is disclosed, characterized in that it contains:

hydrogen peroxide,

Acidic organic acid,

Amine compounds,

Hydrogen peroxide decomposition inhibitors,

Azoles, and

Contains an anti-precipitation agent containing aluminum salt.

This etching solution has performance that satisfies the level currently used in manufacturing in evaluations such as etching rates of copper (Cu) and molybdenum (Mo), taper angles of etched boundary areas, side etching of molybdenum (Mo), residue of molybdenum (Mo), resistance to overetching, precipitates, and hydrogen peroxide decomposition rate.

In addition, for the same purpose, Patent Document 2 discloses an etching solution for a multilayer thin film comprising a copper layer and a molybdenum layer, which comprises: (A) hydrogen peroxide; (B) an inorganic acid containing no fluorine atoms; (C) at least one organic acid selected from succinic acid, glycolic acid, lactic acid, malonic acid and malic acid; (D) an amine compound having 2 to 10 carbon atoms and having amino groups and hydroxyl groups such that the total number of groups is two or more; (E) 5-amino-1H-tetrazole; and, (F) a hydrogen peroxide stabilizer, with a pH of 2.5 to 5.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2015-209568

Patent Document 2: Japanese Patent No. 5051323

Summary of the invention

Problem that the invention aims to solve

Currently, high-resolution standards such as 4K and 8K are being promoted. These standards cannot perform to their full potential in small screens. Therefore, displays with larger screens than before (large-screen FPDs) have been developed. In large-screen FPDs, the distance of the wiring used to drive the pixels becomes longer, so wiring with lower resistance is required. In order to reduce the resistance in copper wiring, it is considered to increase the cross-sectional area of the wiring. However, if the width of the wiring is expanded and the area of 1 pixel is increased, requirements such as high precision cannot be met.

On the other hand, in order to reduce the resistance of the wiring material, it is also considered to use materials such as silver and gold with a lower resistivity than copper, but the cost becomes too high, which is not ideal from the perspective of popularization. As a result, it is necessary to increase the cross-sectional area by increasing the thickness direction of the copper wiring, or reduce the resistance value.

In order to form a wiring with a thick copper, the following technical problems must be solved.

(1) To maintain the same manufacturing rate as before, the etching speed is increased.

(2) The amount of copper ions to be etched in the etching solution increases, so etching can be performed even at a high copper ion concentration.

Solutions for solving problems

The present invention has been conceived to solve the above-mentioned problems, and provides an etching solution for a copper thick film which has a high etching rate and can etch even at a high copper ion concentration.

More specifically, the copper thick film etching solution of the present invention is characterized by comprising:

hydrogen peroxide,

Strong acidic substances,

Amine compounds,

Hydrogen peroxide decomposition inhibitors,

Azoles, and

water,

And the pH is below 2.

Effects of the Invention

The copper thick film etching solution of the present invention has an etching rate of 380 nm/min or more and can continue etching even when the copper ion concentration is 20000 ppm.

Therefore, the thick copper film etching solution of the present invention has the following effects: when etching copper in a thick film state, the process can be processed with a conventional process time, and etching can be continued even if a high concentration of copper ions remain in the etching solution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram showing a cross section of an etched wiring.

Detailed ways

The copper thick film etching solution of the present invention is described below. It should be noted that the following description shows an embodiment of the etching solution of the present invention, and the following embodiments and examples can be changed without departing from the scope of the present invention. It should be noted that in the following description, when "A to B" or "A to B" is used to represent a numerical range, it means "above A and below B". That is, it refers to a range that includes the numerical value A and is greater than the numerical value A, and includes the numerical value B and is less than the numerical value B. In addition, "greater than A" means that it does not include the numerical value A and is greater than the numerical value A, and "lower than A" means that it does not include the numerical value A and is less than the numerical value A.

The copper thick film etching solution of the present invention comprises hydrogen peroxide, a strong acidic substance, an amine compound, a hydrogen peroxide decomposition inhibitor, azoles and water, and has a pH lower than 2. Each component is described in detail below.

＜Hydrogen peroxide＞

In the etching of copper, copper is oxidized to form copper oxide (CuO), which is dissolved by acid. That is, hydrogen peroxide is used as an oxidizing agent to oxidize copper. It should be noted that hydrogen peroxide (Japanese: peroxyhydrogen) and hydrogen peroxide (Japanese: perhydro) are synonymous. Hydrogen peroxide is preferably 4.0 mass% to 5.8 mass% of the total amount of the etching solution.

＜Strongly acidic substances＞

For the copper thick film etching solution of the present invention, in order to increase the etching rate, the pH is lower than 2. Therefore, a strong acidic substance must be used. The strong acidic substance can be an inorganic strong acid or an organic strong acid. In addition, even if it is weakly acidic, as long as the pH of the entire etching solution can be lower than 2.

In general, the strength of an acid is represented by an acid dissociation constant Ka. In addition, the value of the negative logarithm of the acid dissociation constant Ka is called pKa. In the present invention, the strong acidic substance that can be used can use a substance with a pKa of 3 or less, in addition to a substance called a strong acid with a pKa of zero or less. This is because the etching solution contains a variety of substances, but as long as the substance has a pKa of 3 or less, the pH of the entire etching solution can be adjusted to less than 2. Therefore, in the present invention, the strong acidic substance refers to a substance with a pKa of 3 or less.

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

In addition, as the organic acid of the strongly acidic substance, amino acids such as glycine, asparagine, aspartic acid, alanine, glutamic acid, valine, glutamine, glutamic acid, leucine, arginine, isoleucine, lysine, serine, histidine, threonine, phenylalanine, cysteine, tyrosine, methionine, tryptophan, and proline; and compounds such as 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, acetamide, salicylic acid, and 4-nitroaniline can be suitably utilized.

It should be noted that, among organic acids, those having halogen in the skeleton can be cited as those embodying strong acidity. In particular, there are strong acidic substances such as trifluoroacetic acid. However, those containing fluorine in the skeleton have the possibility of becoming hydrofluoric acid, and there is a worry that the substrate is damaged, and therefore, it is expected to be excluded from the strong acidic substances of the present invention.

The strong acidic substance may be contained in an amount of 5 to 15% by mass relative to the total amount of the etching solution. In order to adjust the etching target portion and the taper angle after etching, the chemical described below may be prepared so that the overall pH becomes lower than 2.

＜Organic acid＞

The copper thick film etching solution of the present invention may contain weakly acidic organic acids in addition to strong acidic substances for the purpose of adjusting the cone angle and inhibiting the decomposition of hydrogen peroxide. It should be noted that weakly acidic substances refer to substances with an acid dissociation constant pKa greater than 3.

Specifically, as the organic acid, in addition to aliphatic carboxylic acids having 1 to 18 carbon atoms and aromatic carboxylic acids having 6 to 10 carbon atoms, preferably, amino acids having 1 to 10 carbon atoms are used.

Preferred examples of the aliphatic carboxylic acid 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, glutaric acid, itaconic acid, adipic acid, caproic acid, citric acid, propanetricarboxylic acid, heptanoic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid.

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 amino acids having 1 to 10 carbon atoms include carbamic acid, sarcosine, 4-aminobutyric acid, iminodibutyric acid, nitrilotriacetic acid, etc. The weakly acidic organic acid may be contained in an amount of 1 to 20% by mass based on the total amount of the etching solution.

＜Amine compounds＞

The amine compound plays the role of adjusting the taper angle of the copper film and adjusting the pH of the etching solution. As the amine compound, an amine compound having 2 to 10 carbon atoms can be suitably used. More specifically, preferably 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-methylethylenediamine, N,N-dimethylethylenediamine, trimethylethylenediamine, N-ethylethylenediamine, N,N-diethylethylenediamine, triethylethylenediamine, 1,2,3-triaminopropane, hydrazine, tris(2-aminoethyl)- ... polyamines such as ethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-aminoethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, triethanolamine, 1-amino-2-propanol, N-methylisopropanolamine, N-ethylisopropanolamine, triisopropanolamine, diisopropanolamine, N-propylisopropanolamine, 2-aminopropane-1-ol, N-methyl-2-amino-propane-1-ol, N-ethyl-2-amino-propane-1-ol, 1 -Aminopropane-3-ol, N-methyl-1-aminopropane-3-ol, N-ethyl-1-aminopropane-3-ol, 1-aminobutane-2-ol, N-methyl-1-aminobutane-2-ol, N-ethyl-1-aminobutane-2-ol, 2-aminobutane-1-ol, N-methyl-2-aminobutane-1-ol, N-ethyl-2-aminobutane-1-ol, 3-aminobutane-1-ol, N-methyl-3-aminobutane-1-ol, N-ethyl-3-aminobutane-1-ol, 1-aminobutane-4-ol, N-methyl-1-aminobutane-4-ol, N-ethyl-1-aminobutane-4-ol, 1-amino-2 Alkanolamines such as 1-amino-2-methylpropane-2-ol, 2-amino-2-methylpropane-1-ol, 1-aminopentane-4-ol, 2-amino-4-methylpentane-1-ol, 2-aminohexane-1-ol, 3-aminoheptane-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-diaminopropane-3-ol, 1,3-diaminopropane-2-ol, 2-(2-aminoethoxy)ethanol, 2-(2-aminoethylamino)ethanol, and diglycolamine can be used alone or in combination of two or more.

Among them, 1-amino-2-propanol (CAS No. 78-96-6: hereinafter also referred to as "1A2P"), N,N-diethyl-1,3-propylenediamine (CAS No. 104-78-9: hereinafter also referred to as "NNDPA"), triisopropanolamine (CAS No. 122-20-3: hereinafter also referred to as "TIPA") and diisopropanolamine (CAS No. 110-97-4: hereinafter also referred to as "DIPA") are particularly preferred. In addition, the amine compound is preferably contained in an amount of 0.05 mass % to 5.5 mass % relative to the total amount of the etching solution.

＜Hydrogen peroxide decomposition inhibitor＞

In the copper thick film etching solution of the present invention, hydrogen peroxide is used as an oxidant. Since hydrogen peroxide decomposes itself, a decomposition inhibitor is added to inhibit its decomposition. The hydrogen peroxide decomposition inhibitor is also called a hydrogen peroxide stabilizer (or "hydrogen peroxide stabilizer").

As a hydrogen peroxide decomposition inhibitor, in addition to urea-based hydrogen peroxide decomposition inhibitors such as urea, phenylurea, allylurea, 1,3-dimethylurea, and thiourea, phenylacetamide, phenylethylene glycol, 1-propanol, 2-propanol and other lower alcohols, ethylene glycol monobutyl ether, etc. can also be used. Among them, 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 also referred to as "1P"), ethylene glycol monobutyl ether (CAS No. 111-76-2: hereinafter also referred to as "BG") are particularly preferred. The hydrogen peroxide decomposition inhibitor preferably contains 0.1 mass % to 2.0 mass % relative to the total amount of the etching solution.

＜Azoles＞

The copper thick film etching solution of the present invention contains azoles in order to suppress the etching rate of Cu. In order to increase the etching rate, the copper thick film etching solution of the present invention is set to a pH lower than 2. In this pH range, the etching rate changes sharply according to a slight difference in pH. In this way, the etching rate cannot be adjusted only by the composition ratio of the strongly acidic substance. Therefore, an inhibitor of the etching rate is used.

As azoles, triazoles, tetrazoles, imidazoles, thiazoles, etc. can be suitably used. More specifically, the following examples can be cited. As triazoles, 1H-benzotriazole, 5-methyl-1H-benzotriazole, 3-amino-1H-triazole, etc. can be suitably used.

As tetrazoles, 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole, etc. can be suitably used. In addition, as imidazoles, 1H-imidazole, 1H-benzimidazole, etc. can be suitably used. In addition, as thiazoles, 1,3-thiazole, 4-methylthiazole, etc. can be suitably used.

It should be noted that among them, tetrazoles have a high effect on suppressing the etching rate, and 5-amino-1H-tetrazole (CAS No. 4418-61-5: hereinafter also referred to as "5A1HT"), 5-methyl-1H-tetrazole (CAS No. 4076-36-2: hereinafter also referred to as "5M1HT"), and 5-phenyl-1H-tetrazole (CAS No. 18039-42-4: hereinafter also referred to as "5-phenyl-1HT") are particularly preferred. Among triazoles, 5-methyl-1H-benzotriazole (CAS No. 136-85-6: hereinafter also referred to as "5M1HBTA") and 1H-benzotriazole (CAS No. 95-14-7: hereinafter also referred to as "BTA") are preferred.

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

＜Copper ions＞

For copper etching solution, additional etching solution for dilution is added so that the Cu ion concentration is generally about 2000ppm to 4000ppm. This is because when the copper ion concentration becomes higher, the decomposition rate of hydrogen peroxide becomes faster, so the concentration of hydrogen peroxide in the etching solution decreases. However, the etching solution of the present invention uses a hydrogen peroxide decomposition inhibitor in a highly acidic environment, thereby suppressing the decomposition rate of hydrogen peroxide. Therefore, even if a higher Cu ion concentration is formed, there is no need to add additional etching solution for diluting the Cu ions. More specifically, there is no need to add additional etching solution for dilution until the Cu concentration of the etching solution is 20000ppm.

＜Other＞

In the copper thick film etching solution of the present invention, in addition to these components, water and various additives commonly used within the range that do not hinder the etching performance can also be added. For the purpose of precision machining, it is preferred that no foreign matter is present in the water. Preferably, pure water or ultrapure water is present. Water can be determined as a residual component relative to the above-mentioned components.

In addition, for the range of the ratio of each component of the above description, it is self-evident that it is appropriately adjusted so that the total amount of the etching solution is 100% by mass. In addition, copper ions can be included from the beginning, but the amount relative to other compositions is small, therefore, the composition ratio based on the total amount of the etching solution is ignored.

＜pH, temperature＞

The copper thick film etching solution of the present invention is adjusted to a pH range of less than 2. The etching solution can be used at 20°C to 40°C, more preferably 25°C to 35°C, and most preferably 30°C to 35°C.

＜Save＞

The copper thick film etching solution of the present invention uses hydrogen peroxide. Hydrogen peroxide decomposes itself. Therefore, the etching solution contains a hydrogen peroxide decomposition inhibitor. However, when storing, hydrogen peroxide (or hydrogen peroxide solution) and other liquids can be stored separately. It should be noted that the hydrogen peroxide solution is an aqueous solution of hydrogen peroxide. In addition, only hydrogen peroxide (or hydrogen peroxide solution), water and raw materials other than copper ions (referred to as "etching solution raw materials") can be stored together. It should be noted that the etching solution raw materials can exist as liquid raw materials and powdered raw materials. That is, the copper thick film etching solution of the present invention can be completed by combining the etching solution raw materials, water, and hydrogen peroxide (or hydrogen peroxide solution).

In addition, the etching liquid raw material and water may be mixed to prepare a solution of the etching liquid raw material. The solution of the etching liquid raw material prepared by using the etching liquid raw material and water is called "etching concentrate". Compared with the etching liquid, the etching concentrate only does not contain hydrogen peroxide and the volume is reduced by that amount, so it is convenient for storage and transfer. Therefore, the etching solution for copper thick film of the present invention can be completed by combining the etching concentrate, water and hydrogen peroxide.

Here, the water in the etching concentrate only needs to be present in an amount that dissolves the etching solution raw material. In other words, the water in the etching concentrate may be less than the water in the etching solution. Therefore, if hydrogen peroxide is supplied in the form of a hydrogen peroxide solution as an aqueous solution, the copper thick film etching solution of the present invention can be completed by combining the three types of etching concentrate, water and hydrogen peroxide solution.

In addition, if water is contained in the etching concentrate or the hydrogen peroxide solution, the etching concentrate and the hydrogen peroxide solution may be combined to complete the etching. In addition, in this specification, the ratio of each component of the etching concentrate is expressed as a ratio relative to the total amount of the etching solution when it is completed. Therefore, the total of each component of the etching concentrate will not be 100% by mass.

＜Etching method＞

The object of using the copper thick film etching liquid of the present invention is a copper film formed on a substrate with a thickness of 600 nm or more. An isolation layer formed of other elements may be formed between the substrate and the copper film. The etching method of the present invention is carried out by contacting a substrate with a copper film formed with a thickness of 600 nm or more with the copper thick film etching liquid.

The copper thick film etching solution of the present invention can be stored for a long time by storing hydrogen peroxide, etching solution raw material (or etching concentrate) and water separately. Therefore, when actually used, these are prepared to complete the etching solution. The preparation method is not limited as long as the final concentration of hydrogen peroxide reaches a predetermined concentration.

An example is shown below, in which an etching concentrate is prepared by mixing an etching solution raw material with a certain amount of water. Hydrogen peroxide is usually supplied in the form of a hydrogen peroxide solution having a higher concentration than the hydrogen peroxide concentration of the copper thick film etching solution of the present invention. Therefore, a predetermined amount of hydrogen peroxide solution and etching concentrate are prepared. This process can be referred to as a process of preparing a copper thick film etching solution. The prepared copper thick film etching solution has each component prepared at a predetermined ratio, and the pH becomes lower than 2.

When etching is performed, as described above, an etching solution is used under the conditions of pH less than 2 and 20°C to 40°C. Therefore, the object to be etched is preferably also heated to this temperature by residual heat. There is no particular limitation on the method of bringing the substrate to be processed into contact with the etching solution. The etching solution can be spread on the substrate to be processed from above like a shower, or it can be a method of immersing the substrate to be processed in a pool of etching solution. It can also be called a process of bringing the copper thick film etching solution into contact with the substrate to be processed.

It should be noted that the substrate to be processed refers to a substrate in which 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.

Example

＜Explanation of various evaluation methods＞

The copper thick film etching solution of the present invention was evaluated based on 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 with a thickness of 600 nm was formed by sputtering on a silicon wafer having a thermal oxide film of 100 nm, and the copper film was brought into contact with an etching solution at 30° C. (or 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 4-terminal 4-probe resistivity meter (MCP-T610, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) of a constant current application system. The film thickness change and the etching rate were calculated from the change in the resistance value.

In addition, when the copper etching rate is 380 nm/min or more, it is judged as a circle (○), and other than that, it is judged as being outside the prescribed range and a cross (×).

It should be noted that a “circle” means within the standard range, success or pass, and a “cross” means outside the standard range, failure or failure. The same applies to the following evaluations.

The taper angle is measured as follows. First, a copper film with a thickness of 600nm is formed on a glass substrate by sputtering to prepare a copper thick film sample. A resist layer patterned in the shape of a wiring is formed on the copper film as a substrate for evaluating the taper angle. In other words, the substrate includes a substrate, a copper film, and a patterned resist layer on the copper film. The substrate is immersed in an etching solution and etched during a period of just etching. After washing and drying the etched sample, the wiring portion is cut off and the cut surface is observed.

The cross-section was observed using a SEM (manufactured by Hitachi: SU8020) at an acceleration voltage of 1 kV and 30,000 to 50,000 times. During the SEM observation, the shape of the etched portion was also observed. It should be noted that appropriate etching is the time from the start of etching until the film passes light. The moment when the film passes light is confirmed by visual inspection.

A schematic diagram of the cross-sectional shape is shown in FIG1 . As shown in FIG1 , the angle 3 formed by the substrate 1 and the etched inclined surface 5 is set as a taper angle (°). If the taper angle 3 is 30° to 80°, it is judged as a circle (○). If it is outside the range of this angle, it is judged as a cross (×). It should be noted that in FIG1 , the Cu layer is represented by the mark 2 and the anti-etching layer is represented by the mark 4.

(Example 1)

The mixture contained 8.33 mass% of nitric acid as a strongly acidic substance.

NNDPA (N,N-diethyl-1,3-propylenediamine) as an amine compound: 5.24 mass%

FN (phenylurea) as a hydrogen peroxide stabilizer 0.12 mass%

5M1HT (5-methyl-1H-tetrazole) as azole: 0.01 mass%

The etching liquid raw material was modulated with 72.41% by mass of water to prepare an etching concentrate. It should be noted that the ratio of each component in the etching concentrate is expressed as a ratio relative to the total amount when mixed with the hydrogen peroxide solution described later to complete the etching solution. The same applies to the following examples and comparative examples.

13.89 mass % of 35% hydrogen peroxide solution (4.86 mass % of hydrogen peroxide and 9.03 mass % of water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution having a hydrogen peroxide concentration of 4.86 mass %. It should be noted that the total amount of water was 81.44 mass %. Furthermore, copper powder was added to adjust the copper ion concentration to 20000 ppm. In addition, the solution was used at a liquid temperature of 35°C. The concentrations of each component in the overall etching solution and the results of each evaluation item are shown in Table 1.

(Example 2)

The mixture contains 9.88 mass % of malonic acid as a strongly acidic substance,

1A2P (1-amino-2-propanol) as an amine compound: 1.35 mass %,

1P (1-propanol) as a hydrogen peroxide stabilizer 0.68 mass%,

5A1HT (5-amino-1H-tetrazole) as azole: 0.05 mass%

The etching liquid raw material was mixed with 75.70 mass % of water to prepare an etching concentrate.

12.34 wt% of 35% hydrogen peroxide solution (4.32 mass% of hydrogen peroxide and 8.02 mass% of water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 4.32 mass%. It should be noted that the total amount of water was 83.72 mass%. Furthermore, copper powder was added to adjust the copper ion concentration to 20000 ppm. In addition, the solution was used at a liquid temperature of 35°C. The concentrations of each component in the entire etching solution and the results of each evaluation item are shown in Table 1.

(Example 3)

The mixture contains 6.93% by mass of sulfuric acid as a strongly acidic substance.

Glycine 1.84 mass%

TIPA (triisopropanolamine) as an amine compound: 2.49 mass%

Urea as a hydrogen peroxide stabilizer 0.64 mass%

5M1HBTA (5-methyl-1H-benzotriazole) as azole: 0.03 mass%

The etching liquid raw material was mixed with 73.36 mass % of water to prepare an etching concentrate.

14.71 wt% of 35% hydrogen peroxide solution (5.15 mass% of hydrogen peroxide and 9.56 mass% of water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 5.15 mass%. It should be noted that the total amount of water is 82.92 mass%. Furthermore, copper powder was added to adjust the copper ion concentration to 20000 ppm. In addition, the solution was used at a liquid temperature of 35°C. The concentrations of each component in the entire etching solution and the results of each evaluation item are shown in Table 1.

(Example 4)

The mixture contains 7.20 mass % of malonic acid as a strongly acidic substance,

Glutaric acid as organic acid 6.77 mass%

DIPA (diisopropanolamine) as an amine compound: 0.06 mass%

BG (ethylene glycol monobutyl ether) as a hydrogen peroxide stabilizer 0.96 mass%,

5-phenyl-1HT (5-phenyl-1H-tetrazole) as azole: 0.03 mass%

The etching liquid raw material was mixed with 70.32 mass % of water to prepare an etching concentrate.

14.66 wt% of 35% hydrogen peroxide solution (5.13 wt% hydrogen peroxide and 9.53 wt% water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 5.13 wt%. It should be noted that the total amount of water was 79.85 wt%. Furthermore, copper powder was added to adjust the copper ion concentration to 20,000 ppm. In addition, the solution was used at a liquid temperature of 35°C. The concentrations of each component in the overall etching solution and the results of each evaluation item are shown in Table 1.

(Example 5)

The mixture contained 7.04 mass% of ethanesulfonic acid as a strongly acidic substance.

Malic acid as organic acid 4.4 mass%

TIPA (triisopropanolamine) as an amine compound: 1.04 mass%

BG (ethylene glycol monobutyl ether) as a hydrogen peroxide stabilizer 0.85 mass%,

BTA (benzotriazole) as azole: 0.02 mass%

The etching liquid raw material was mixed with 71.56 mass % of water to prepare an etching concentrate.

15.09 wt% of 35% hydrogen peroxide solution (5.28 wt% hydrogen peroxide and 9.81 wt% water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 5.28 wt%. It should be noted that the total amount of water was 81.37 wt%. Furthermore, copper powder was added to adjust the copper ion concentration to 20,000 ppm. In addition, the solution was used at a liquid temperature of 35°C. The concentrations of each component in the overall etching solution and the results of each evaluation item are shown in Table 1.

(Example 6)

The mixture contained 7.04 mass% of ethanesulfonic acid as a strongly acidic substance.

TIPA (triisopropanolamine) as an amine compound: 1.04 mass%

BG (ethylene glycol monobutyl ether) as a hydrogen peroxide stabilizer 0.85 mass%,

BTA (benzotriazole) as azole: 0.02 mass%

The etching liquid raw material was mixed with 75.96 mass % of water to prepare an etching concentrate.

15.09 wt% of 35% hydrogen peroxide solution (5.28 mass% of hydrogen peroxide and 9.81 mass% of water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 5.28 mass%. It should be noted that the total amount of water is 85.77 mass%. Furthermore, copper powder was added to adjust the copper ion concentration to 20000 ppm. In addition, the solution was used at a liquid temperature of 35°C. The concentrations of each component in the entire etching solution and the results of each evaluation item are shown in Table 1.

(Comparative Example 1)

The mixture contains 10.00 mass% of nitric acid as a strongly acidic substance.

NNDPA (N,N-diethyl-1,3-propylenediamine) as an amine compound: 12.50 mass%

FN (phenylurea) as a hydrogen peroxide stabilizer 0.10 mass%

5M1HT (5-methyl-1H-tetrazole) as azoles 0.10 mass%

The etching liquid raw material was mixed with 65.87 mass % of water to prepare an etching concentrated liquid.

11.43 wt% of 35% hydrogen peroxide solution (4.00 mass% of hydrogen peroxide and 7.43 mass% of water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 4.00 mass%. It should be noted that the total amount of water is 73.30 mass%. Furthermore, copper powder was added to dissolve the copper ion concentration to 20000 ppm, but it was not completely dissolved. In addition, it was used at a liquid temperature of 35°C. The concentrations of each component in the entire etching solution and the results of each evaluation item are shown in Table 2.

(Comparative Example 2)

The mixture contains 6.00 mass% of ethanesulfonic acid as a strongly acidic substance.

TIPA (triisopropanolamine) as an amine compound: 9.70 mass%

BG (ethylene glycol monobutyl ether) as a hydrogen peroxide stabilizer 0.70 mass%

BTA (benzotriazole) as azole: 0.02 mass%

The etching liquid raw material was mixed with 68.49 mass % of water to prepare an etching concentrate.

15.09 wt% of 35% hydrogen peroxide solution (5.28 wt% hydrogen peroxide and 9.81 wt% water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 5.28 wt%. It should be noted that the total amount of water is 78.30 wt%. Furthermore, copper powder was added to dissolve the copper ion concentration to 20,000 ppm, but it was not completely dissolved. In addition, it was used at a liquid temperature of 35°C. The concentrations of each component in the overall etching solution and the results of each evaluation item are shown in Table 2.

(Comparative Example 3)

The mixture contains 15.80 mass% of malonic acid as a strongly acidic substance.

1A2P (1-amino-2-propanol) as an amine compound 8.40 mass%

1P (1-propanol) as a hydrogen peroxide stabilizer 0.60 mass%

5A1HT (5-amino-1H-tetrazole) as azole: 0.05 mass%

The etching liquid raw material was mixed with 62.86 mass % of water to prepare an etching concentrate.

12.29 wt% of 35% hydrogen peroxide solution (4.30 wt% hydrogen peroxide and 7.99 wt% water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 4.30 wt%. It should be noted that the total amount of water was 70.85 wt%. Furthermore, copper powder was added to dissolve the copper ion concentration to 1000 ppm. In addition, the solution was used at a liquid temperature of 35°C. The concentrations of each component in the overall etching solution and the results of each evaluation item are shown in Table 2.

(Comparative Example 4)

The mixture contained 6.90 mass% of nitric acid as a strongly acidic substance.

NNDPA (N,N-diethyl-1,3-propylenediamine) as an amine compound 8.34 mass%

FN (phenylurea) as a hydrogen peroxide stabilizer 0.10 mass%

5M1HT (5-methyl-1H-tetrazole) as azoles 0.10 mass%

The etching liquid raw material was mixed with 71.99 mass % of water to prepare an etching concentrate.

12.57 wt% of 35% hydrogen peroxide solution (4.40 mass% of hydrogen peroxide and 8.17 mass% of water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 4.40 mass%. It should be noted that the total amount of water is 80.16 mass%. Furthermore, copper powder was added to dissolve the copper ion concentration to 1000 ppm, but it was not completely dissolved. In addition, it was used at a liquid temperature of 35°C. The concentrations of each component in the entire etching solution and the results of each evaluation item are shown in Table 2.

(Comparative Example 5)

The mixture contained 6.00 mass% of ethanesulfonic acid as a strongly acidic substance.

TIPA (triisopropanolamine) as an amine compound: 5.96 mass%

BG (ethylene glycol monobutyl ether) as a hydrogen peroxide stabilizer 0.82 mass%

BTA (benzotriazole) as azole: 0.04 mass%

The etching liquid raw material was mixed with 72.09 mass % of water to prepare an etching concentrate.

15.09 wt% of 35% hydrogen peroxide solution (5.28 mass% of hydrogen peroxide and 9.81 mass% of water relative to the total amount of the etching solution) was mixed with the etching concentrate to prepare an etching solution with a hydrogen peroxide concentration of 5.28 mass%. It should be noted that the total amount of water is 81.90 mass%. Furthermore, copper powder was added to dissolve the copper ion concentration to 1000 ppm, but it was not completely dissolved. In addition, it was used at a liquid temperature of 35°C. The concentrations of each component in the entire etching solution and the results of each evaluation item are shown in Table 2.

[Table 1]

[Table 2]

Referring to Table 1, when using an inorganic acid or an organic acid, as long as it is a strong acidic substance, the pH of the entire etching solution can be adjusted to less than 2. In addition, the copper thick film etching solution prepared in this way can achieve an etching rate of more than 380 nm/min in a copper ion environment such as 20,000 ppm. In addition, the cone angle can be adjusted to 30° to 80°. In addition, there is no particular problem with its shape.

On the other hand, see Table 2. The materials used are the same as those in the examples shown in Table 1, but the high ion concentration of 20,000 ppm would not have been achieved if the pH of the entire etching solution had not been set to less than 2. Copper ions could not be dissolved, and etching could not be performed.

In addition, when the strong acidic substance is composed of only organic acid, the amine compound is preferably 0.05 mass % or more and less than 2.0 mass % (see Examples 2, 4, 5, and 6). This is considered to be because the pKa of the strong acidic substance of the organic acid is higher than that of the inorganic acid. Therefore, if the amine compound is added excessively, the pH of the entire etching solution cannot be lower than 2.

As described above, the copper thick film etching solution of the present invention can achieve a high etching rate even at a high copper ion concentration, and can etch thick copper films on large-area substrates at a processing speed of an actual mass production machine.

Industrial Applicability

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

Description of Reference Numerals

1. Substrate

2 Cu layer

3 Cone Angle

4. Anti-corrosion layer

5 Inclined surface

Claims (5)

1. An etching solution for copper thick films, comprising:

Hydrogen peroxide,

A strongly acidic substance,

An amine compound,

A hydrogen peroxide decomposition inhibitor,

Azoles, and

The water is used as the water source,

And the pH is not more than 1.9,

The amine compound includes polyamines such as ethylenediamine, trimethylene diamine, tetramethylenediamine, 1, 2-propane diamine, 1, 3-propane diamine, N-dimethyl-1, 3-propane diamine, N-diethyl-1, 3-propane diamine, 1, 3-diaminobutane, 2, 3-diaminobutane, pentamethylene diamine, 2, 4-diaminopentane, hexamethylenediamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, N-methylethylenediamine, N-dimethylethylenediamine, trimethylethylenediamine, N-ethylethylenediamine, N-diethyl ethylenediamine, triethylethylenediamine, 1,2, 3-triaminopropane, hydrazine, tris (2-aminoethyl) amine, tetrakis (aminomethyl) methane, diethylenetriamine, triethylenetetramine, tetraethylpentamine, heptaethyleneoctamine, nonaethylenedecamine, diazabicycloundecene, and the like; ethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-aminoethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, triethanolamine, 1-amino-2-propanol, N-methylisopropanolamine, N-ethylisopropanolamine, triisopropanolamine, diisopropanolamine, N-propylisopropanolamine, 2-aminopropane-1-ol, N-methyl-2-amino-propane-1-ol, N-ethyl-2-amino-propane-1-ol, 1-aminopropane-3-ol, N-methyl-1-aminopropane-3-ol, N-ethyl-1-aminopropane-3-ol, 1-aminobutan-2-ol, N-methyl-1-aminobutan-2-ol, N-ethyl-1-aminobutan-2-ol, 2-aminobutan-1-ol, N-methyl-2-aminobutan-1-ol, N-ethyl-2-aminobutan-1-ol, 3-aminobutan-1-ol, N-methyl-3-amino-1-aminobutan-3-ol, N-ethyl-1-aminobutan-4-amino-1-ethyl-2-ol, at least 1 of N-methyl-1-aminobutan-4-ol, N-ethyl-1-aminobutan-4-ol, 1-amino-2-methylpropan-2-ol, 2-amino-2-methylpropan-1-ol, 1-aminopentan-4-ol, 2-amino-4-methylpentan-1-ol, 2-aminohexane-1-ol, 3-aminoheptane-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-diaminopropane-3-ol, 1, 3-diaminopropane-2-ol, 2- (2-aminoethoxy) ethanol, 2- (2-aminoethylamino) ethanol, diglycolamine,

The azole comprises at least 1 of 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole, 1H-imidazole, 1H-benzimidazole, 1, 3-thiazole, 4-methylthiazole,

The hydrogen peroxide decomposition inhibitor comprises at least 1 of urea, phenylurea, allylurea, 1, 3-dimethylurea, thiourea, phenylacetamide, phenylglycol, 1-propanol, 2-propanol, ethylene glycol monobutyl ether.

2. The etching solution for a copper thick film according to claim 1, further comprising a weakly acidic organic acid.

3. An etching concentrate for copper thick films comprising:

a strongly acidic substance,

An amine compound,

A hydrogen peroxide decomposition inhibitor,

Azoles, and

The water is used as the water source,

Adding hydrogen peroxide to form 4.0-5.8 wt%,

So that the pH is not more than 1.9,

The amine compound includes polyamines such as ethylenediamine, trimethylene diamine, tetramethylenediamine, 1, 2-propane diamine, 1, 3-propane diamine, N-dimethyl-1, 3-propane diamine, N-diethyl-1, 3-propane diamine, 1, 3-diaminobutane, 2, 3-diaminobutane, pentamethylene diamine, 2, 4-diaminopentane, hexamethylenediamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, N-methylethylenediamine, N-dimethylethylenediamine, trimethylethylenediamine, N-ethylethylenediamine, N-diethyl ethylenediamine, triethylethylenediamine, 1,2, 3-triaminopropane, hydrazine, tris (2-aminoethyl) amine, tetrakis (aminomethyl) methane, diethylenetriamine, triethylenetetramine, tetraethylpentamine, heptaethyleneoctamine, nonaethylenedecamine, diazabicycloundecene, and the like; ethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-aminoethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, triethanolamine, 1-amino-2-propanol, N-methylisopropanolamine, N-ethylisopropanolamine, triisopropanolamine, diisopropanolamine, N-propylisopropanolamine, 2-aminopropane-1-ol, N-methyl-2-amino-propane-1-ol, N-ethyl-2-amino-propane-1-ol, 1-aminopropane-3-ol, N-methyl-1-aminopropane-3-ol, N-ethyl-1-aminopropane-3-ol, 1-aminobutan-2-ol, N-methyl-1-aminobutan-2-ol, N-ethyl-1-aminobutan-2-ol, 2-aminobutan-1-ol, N-methyl-2-aminobutan-1-ol, N-ethyl-2-aminobutan-1-ol, 3-aminobutan-1-ol, N-methyl-3-amino-1-aminobutan-3-ol, N-ethyl-1-aminobutan-4-amino-1-ethyl-2-ol, at least 1 of N-methyl-1-aminobutan-4-ol, N-ethyl-1-aminobutan-4-ol, 1-amino-2-methylpropan-2-ol, 2-amino-2-methylpropan-1-ol, 1-aminopentan-4-ol, 2-amino-4-methylpentan-1-ol, 2-aminohexane-1-ol, 3-aminoheptane-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-diaminopropane-3-ol, 1, 3-diaminopropane-2-ol, 2- (2-aminoethoxy) ethanol, 2- (2-aminoethylamino) ethanol, diglycolamine,

The azole comprises at least 1 of 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole, 1H-imidazole, 1H-benzimidazole, 1, 3-thiazole, 4-methylthiazole,

The hydrogen peroxide decomposition inhibitor comprises at least 1 of urea, phenylurea, allylurea, 1, 3-dimethylurea, thiourea, phenylacetamide, phenylglycol, 1-propanol, 2-propanol, ethylene glycol monobutyl ether.

4. The etching concentrate for a copper thick film according to claim 3, further comprising a weakly acidic organic acid.

5. An etching method for a copper thick film, comprising the steps of:

A step of adding hydrogen peroxide to the etching concentrate for copper thick film to form 4.0 to 5.8 mass% of the whole, thereby preparing the etching solution for copper thick film,

The etching concentrated solution for copper thick films comprises:

a strongly acidic substance,

An amine compound,

A hydrogen peroxide decomposition inhibitor,

Azoles, and

The water is used as the water source,

Adding hydrogen peroxide to form 4.0-5.8 wt%,

So that the pH is 1.9 or less; and, a step of, in the first embodiment,

A step of bringing a substrate having a copper film formed at a thickness of 600nm or more into contact with the etching liquid for a copper thick film,

The amine compound includes polyamines such as ethylenediamine, trimethylene diamine, tetramethylenediamine, 1, 2-propane diamine, 1, 3-propane diamine, N-dimethyl-1, 3-propane diamine, N-diethyl-1, 3-propane diamine, 1, 3-diaminobutane, 2, 3-diaminobutane, pentamethylene diamine, 2, 4-diaminopentane, hexamethylenediamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, N-methylethylenediamine, N-dimethylethylenediamine, trimethylethylenediamine, N-ethylethylenediamine, N-diethyl ethylenediamine, triethylethylenediamine, 1,2, 3-triaminopropane, hydrazine, tris (2-aminoethyl) amine, tetrakis (aminomethyl) methane, diethylenetriamine, triethylenetetramine, tetraethylpentamine, heptaethyleneoctamine, nonaethylenedecamine, diazabicycloundecene, and the like; ethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-aminoethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, triethanolamine, 1-amino-2-propanol, N-methylisopropanolamine, N-ethylisopropanolamine, triisopropanolamine, diisopropanolamine, N-propylisopropanolamine, 2-aminopropane-1-ol, N-methyl-2-amino-propane-1-ol, N-ethyl-2-amino-propane-1-ol, 1-aminopropane-3-ol, N-methyl-1-aminopropane-3-ol, N-ethyl-1-aminopropane-3-ol, 1-aminobutan-2-ol, N-methyl-1-aminobutan-2-ol, N-ethyl-1-aminobutan-2-ol, 2-aminobutan-1-ol, N-methyl-2-aminobutan-1-ol, N-ethyl-2-aminobutan-1-ol, 3-aminobutan-1-ol, N-methyl-3-amino-1-aminobutan-3-ol, N-ethyl-1-aminobutan-4-amino-1-ethyl-2-ol, at least 1 of N-methyl-1-aminobutan-4-ol, N-ethyl-1-aminobutan-4-ol, 1-amino-2-methylpropan-2-ol, 2-amino-2-methylpropan-1-ol, 1-aminopentan-4-ol, 2-amino-4-methylpentan-1-ol, 2-aminohexane-1-ol, 3-aminoheptane-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-diaminopropane-3-ol, 1, 3-diaminopropane-2-ol, 2- (2-aminoethoxy) ethanol, 2- (2-aminoethylamino) ethanol, diglycolamine,

The azole comprises at least 1 of 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole, 1H-imidazole, 1H-benzimidazole, 1, 3-thiazole, 4-methylthiazole,

The hydrogen peroxide decomposition inhibitor comprises at least 1 of urea, phenylurea, allylurea, 1, 3-dimethylurea, thiourea, phenylacetamide, phenylglycol, 1-propanol, 2-propanol, ethylene glycol monobutyl ether.