JP7449129B2 - Etching liquid composition and etching method for copper-based layer - Google Patents

Description

The present invention relates to an etching solution composition containing specific components used for etching a copper-based layer, and an etching method using the etching solution composition.

As a method for forming circuits on printed circuit boards and semiconductor package boards, there are two methods: the additive method, in which a circuit pattern is added to the board later, and the subtractive method (etching method), in which the circuit pattern is formed by removing unnecessary parts from the metal foil on the board. Are known. Currently, the subtractive method (etching method), which has low manufacturing costs, is generally employed for manufacturing printed circuit boards. With the miniaturization and higher performance of electronic devices in recent years, the development of etching solutions that can form fine patterns on printed circuit boards with high productivity is progressing.

For example, Patent Document 1 describes a copper etching solution containing copper chloride, hydrochloric acid, and dodecyltrimethylammonium chloride. Furthermore, Patent Document 2 discloses a germanium etching solution containing tetraalkylammonium chloride, hydrochloric acid, and nitric acid. Further, Patent Document 3 discloses a NiPt etching solution containing tetramethylammonium chloride and nitric acid.

Japanese Patent Application Publication No. 2015-178656 Japanese Patent Application Publication No. 2015-162508 JP2017-017360A

However, when attempting to form fine lines by etching a copper-based layer using the etching solution disclosed in the above-mentioned patent document, it is difficult to obtain a sufficient etching rate, and it is difficult to form a fine pattern with the desired dimensional accuracy. The problem was that it was difficult to form.

Therefore, it is an object of the present invention to provide an etching solution composition for a copper-based layer that is capable of forming a fine pattern with excellent dimensional accuracy with good productivity. The present invention also provides an etching method using the above composition.

The present inventors have made extensive studies to obtain the above-mentioned composition, and as a result, have discovered that a composition containing specific components can solve the above-mentioned problems, leading to the present invention.

That is, according to the present invention, it contains (A) 0.1 to 20% by mass of cupric ions, (B) 0.01 to 5% by mass of an ammonium compound represented by the following general formula (1), and water. An etchant composition for a copper-based layer is provided.

（前記一般式（１）中、Ｒ^１ はフェニル基又はベンジル基を表し、Ｒ ^２ ～Ｒ^４は、それぞれ独立に、炭素原子数１～３のアルキル基を表し、Ｘは塩素原子又は臭素原子を表す。）

(In the general formula (1), R ¹ represents a phenyl group or a benzyl group, R ² to R ⁴ each independently represent an alkyl group having 1 to 3 carbon atoms, and X is a chlorine atom or a bromine atom. (represents an atom )

Further, according to the present invention, there is provided an etching method that includes etching a copper-based layer using the above etching solution composition for a copper-based layer.

According to the present invention, it is possible to provide an etching solution composition for a copper-based layer that can form a fine pattern with excellent dimensional accuracy with good productivity. Further, according to the present invention, an etching method using the above composition can be provided.

FIG. 3 is a cross-sectional view schematically showing a test substrate after etching.

Embodiments of the present invention will be described in detail below. An etchant composition according to an embodiment of the present invention is used for etching a copper-based layer, that is, an etchant composition for a copper-based layer. This etching solution composition for a copper-based layer may be simply referred to as an "etching solution composition" or "this composition" below. This composition contains (A) cupric ion (hereinafter also referred to as "component (A)"); (B) an ammonium compound represented by general formula (1) (hereinafter also referred to as "component (B)"). It is an aqueous solution containing water as an essential component.

The "copper-based layer" described in this specification may be any layer containing copper, and is not particularly limited, but includes, for example, a conductive layer containing 10% by mass or more of copper. For example, it is a general term for a layer made of at least one type selected from copper alloys such as metallic copper and copper-nickel alloys. Metallic copper can be particularly preferably used as the copper-based layer.

"Etching" as used herein means a plastic shaping or surface processing technique that utilizes the corrosive action of chemicals, etc., and its specific uses include removal agents, surface smoothing agents, surface roughening agents, etc. Examples include cleaning agents, pattern-forming agents, and cleaning solutions for components that have adhered to the substrate in small amounts. The present composition can be suitably used as a removing agent since the removal rate of a copper-containing layer is fast. Furthermore, when the present composition is used to form a finely shaped pattern having a three-dimensional structure, it is possible to obtain a pattern with a desired shape such as a rectangle, so it is suitable as a pattern forming agent. Can be used.

Component (A) is cupric ion (copper (II) ion, Cu ²⁺ ). A source of cupric ions can be used to include cupric ions in the composition. As a source of cupric ions, a compound capable of producing cupric ions in water can be used. Examples of such sources of cupric ions include copper(II) chloride, copper(II) bromide, copper(II) sulfate, and copper(II) hydroxide. One of these cupric ion sources can be used alone or in combination of two or more. Among these sources of cupric ions, when copper (II) chloride is used, the stability of the etching solution composition for copper-based layers is good, and furthermore, the etching rate is easy to control. Particularly preferred.

The concentration of component (A) in the present composition is 0.1 to 20% by mass in terms of cupric ions, based on the total mass of the etching solution composition for copper-based layers. The concentration of component (A) may be adjusted as appropriate within the above concentration range depending on the thickness and width of the copper-based layer that is the object to be etched, but if it is 1 to 15% by mass, the etching rate can be easily controlled. Particularly preferred. If the concentration of component (A) is less than 0.1% by mass, a sufficient etching rate cannot be obtained. On the other hand, if the concentration of component (A) exceeds 20% by mass, it may be difficult to control the etching rate.

Component (B) is an ammonium compound represented by the following general formula (1). One type of these components (B) can be used alone or two or more types can be used in combination.

（一般式（１）中、Ｒ^１～Ｒ^４は、それぞれ独立に、フェニル基、ベンジル基、又は炭素原子数１～３のアルキル基を表し、Ｘはハロゲン原子を表す。）

(In general formula (1), R ¹ to R ⁴ each independently represent a phenyl group, a benzyl group, or an alkyl group having 1 to 3 carbon atoms, and X represents a halogen atom.)

In general formula (1), R ¹ to R ⁴ each independently represent a phenyl group, a benzyl group, or an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include methyl group, ethyl group, normal propyl group, and isopropyl group. It is preferable that R ² to R ⁴ are each independently an alkyl group having 1 to 3 carbon atoms, since this tends to further enhance the effect of forming fine patterns with excellent dimensional accuracy and high productivity. Among these, in one embodiment of the present composition, ^it is more preferable that R ¹ to R ⁴ are each independently an alkyl group having 1 to 3 carbon atoms; It is more preferable that is a phenyl group or a benzyl group, and R ² to R ⁴ are each independently an alkyl group having 1 to 3 carbon atoms.

In general formula (1), X represents a halogen atom. X is preferably a chlorine atom or a bromine atom, and is particularly preferably a chlorine atom, since the effect of forming a fine pattern with excellent dimensional accuracy with good productivity is likely to be further enhanced.

Preferred specific examples of the compound represented by general formula (1) include the following chemical formula No. 1~No. Compounds represented by 24 can be mentioned. The following chemical formula No. 1~No. In 24, "Me" represents a methyl group, "Et" represents an ethyl group, and "nPr" represents a normal propyl group.

Among the above components (B), more preferable compounds are shown in parentheses with the above chemical formula No. For example, N-benzyltrimethylammonium chloride (No. 8), N-benzyltrimethylammonium bromide (No. 20), N-benzyltriethylammonium chloride (No. 10), N-benzyltriethylammonium bromide (No. 22), trimethylphenylammonium chloride (No. 7), trimethylphenylammonium bromide (No. 19), tetramethylammonium chloride (No. 1), and tetramethylammonium bromide (No. 13). Can be done. It is more preferable to use one of these alone or in combination of two or more.

In one embodiment of the present composition, component (B) is N-benzyltrimethylammonium chloride (No. 8 ), N-benzyltrimethylammonium bromide (No. 20), N-benzyltriethylammonium chloride (No. 10), trimethylphenylammonium chloride (No. 7), and tetramethylammonium chloride (No. 1). It is more preferable to contain at least one selected one, and it is particularly preferable to contain at least one of N-benzyltrimethylammonium chloride (No. 8) and N-benzyltrimethylammonium bromide (No. 20).

The concentration of component (B) in the present composition is 0.01 to 5% by mass, preferably 0.03 to 4% by mass, based on the total mass of the etching solution composition for copper-based layers. More preferably, it is 0.05 to 3% by mass. If the concentration of component (B) is less than 0.01% by mass, it may not be possible to obtain the desired effect by blending component (B). On the other hand, if the concentration of the component (B) exceeds 5% by mass, defects in the pattern shape of the thin lines may easily occur.

In the present composition, the mass ratio of component (B) to component (A) is preferably (B)/(A) = 0.01 to 1, more preferably 0.03 to 0.5, More preferably, it is 0.05 to 0.3. When the value of (B)/(A) is 1 or less, it becomes easier to form a fine wiring pattern with excellent dimensional accuracy. On the other hand, when the value of (B)/(A) is 0.01 or more, it becomes easier to form a pattern with good productivity.

This composition is an aqueous solution containing water as an essential component, in which each component is dissolved in water. As the water, water from which ionic substances and impurities have been removed, such as ion exchange water, pure water, and ultrapure water, can be used. The content of water in the present composition may be about 50 to 99% by mass based on the total mass of the etching solution composition for copper-based layers.

The present composition preferably contains chloride ions (Cl ⁻ ) since this improves the etching rate. A source of chloride ions can be used to include chloride ions in the composition. As a source of chloride ions, a compound that can generate chloride ions in water can be used. Examples of sources of such chloride ions include copper(II) chloride, which can also be used as a source of the above-mentioned component (A), and copper (II) in general formula (1), which can also be used as the above-mentioned component (B). When X is a chlorine atom, compounds represented by the formula, as well as other chloride ion sources described below, etc. can be mentioned. One or more of these can be used.

Examples of the above chloride ion sources include hydrogen chloride, sodium chloride, calcium chloride, potassium chloride, barium chloride, ammonium chloride, iron (III) chloride, manganese (II) chloride, cobalt (II) chloride, and cerium chloride. (III), zinc chloride (II), etc. can be used. One type of these chloride ion sources can be used alone or two or more types can be used in combination.

Among the above-mentioned sources of chloride ions, hydrogen chloride and copper (II) chloride are preferred, and hydrogen chloride is more preferred, for reasons such as ease of controlling the etching rate and ease of controlling the shape of the wiring pattern. .

The concentration of chloride ions in the present composition is preferably 0.1 to 30% by mass, more preferably 1 to 28% by mass, based on the total mass of the etching solution composition for copper-based layers. It is preferably 5 to 25% by mass, and more preferably 5 to 25% by mass. The concentration of chloride ions can be adjusted as appropriate depending on the thickness, width, etc. of the object to be etched. When the concentration of chloride ions is 0.1% by mass or more, the etching rate may be improved. When the concentration of chloride ions is 30% by mass or less, problems such as corrosion of device members may be less likely to occur.

In addition to component (A), component (B), water, and chloride ions, the present composition may contain well-known additives and solvents as long as they do not impair the effects of the present invention. Additives include a stabilizer for the etching solution composition, a solubilizer for each component, a pH adjuster, a specific gravity adjuster, a viscosity adjuster, a wettability improver, a chelating agent, an oxidizing agent, a reducing agent, and a surfactant. , rust preventives, etc. The concentration of these additives may be within the range of 0.001 to 50% by mass, preferably within the range of 0.001 to 49% by mass, and preferably within the range of 0.001 to 40% by mass. It is more preferable that

Examples of pH adjusters include inorganic acids such as sulfuric acid and nitric acid, and salts thereof; water-soluble organic acids and salts thereof; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; Alkaline earth metal hydroxides such as calcium hydroxide, strontium hydroxide, and barium hydroxide; Carbonates of alkali metals such as lithium carbonate, sodium carbonate, and potassium carbonate; Carbonates of alkali metals such as sodium hydrogen carbonate and potassium hydrogen carbonate Examples include hydrogen salts; quaternary ammonium hydroxides such as tetramethylammonium hydroxide and choline; organic amines such as ethylamine, diethylamine, triethylamine, and hydroxyethylamine; ammonium carbonate; ammonium hydrogen carbonate; ammonia; and the like. These pH adjusters can be used alone or in combination of two or more. The content of the pH adjuster may be such that the pH of the etching solution composition becomes a desired pH.

Examples of the chelating agent include ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, tetraethylenepentaminehetaacetic acid, pentaethylenehexamineoctaacetic acid, nitrilotriacetic acid, and alkali metal (preferably sodium) salts thereof. Aminocarboxylic acid chelating agents; Phosphonic acid chelating agents such as hydroxyethylidene diphosphonic acid, nitrilotrismethylenephosphonic acid, phosphonobutanetricarboxylic acid, and their alkali metal (preferably sodium) salts; oxalic acid, malonic acid , succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, fumaric acid, malic acid, tartaric acid, citric acid, their anhydrides, and their alkali metal (preferably sodium) salts. Examples include monoanhydrides and dianhydrides obtained by dehydrating acid compounds and divalent or higher carboxylic acid compounds. The concentration of the chelating agent in the etching solution composition generally ranges from 0.01 to 40% by weight, preferably from 0.05 to 30% by weight.

As the surfactant, cationic surfactants and amphoteric surfactants can be used. Examples of cationic surfactants include alkyl (alkenyl) pyridinium salts, alkyl (alkenyl) isoquinolinium salts, dialkyl (alkenyl) morphonium salts, polyoxyethylene alkyl (alkenyl) amines, alkyl (alkenyl) amine salts, and polyamine fatty acid derivatives. , amyl alcohol fatty acid derivatives, benzalkonium chloride, benzethonium chloride, and the like. Examples of amphoteric surfactants include carboxybetaine, sulfobetaine, phosphobetaine, amide amino acid, and imidazolinium betaine surfactants. The concentration of surfactant in the etching solution composition generally ranges from 0.001 to 10% by weight.

As rust preventives, aminotriazoles such as amino-1,2,4-triazole; triazole rust preventives such as tolyltriazole; benzotriazole, 5-methyl/1H-benzotriazole, 4-methyl/1H-benzotriazole , 5,6-dimethyl-1H-benzotriazole and other alkylbenzotriazoles; alkoxybenzotriazoles such as butyloxybenzotriazole, pentyloxybenzotriazole and hexyloxybenzotriazole; benzotriazole-based protectants such as tolylbenzotriazole and mercaptobenzotriazole; Rust agents; aminotetrazoles such as tetrazole and 5-aminotetrazole; tetrazole-based rust inhibitors such as 5-phenyl-1,2,3,4-tetrazole and 1-phenyl-5-mercapto-tetrazole; imidazole, alkylimidazole, Imidazole rust inhibitors such as 2-phenyl-imidazole, 2-phenyl-4-methyl-imidazole, polyvinyl-imidazole, N-trimethoxysilylpropyl-imidazole, imidazole ring-containing diamino-s-triazine; benzimidazole, 2- Benzimidazole rust inhibitors such as mercapto-benzimidazole; naphthoimidazole rust inhibitors such as naphthoimidazole; thiazole rust inhibitors such as thiazole and 2-mercapto-thiazole; benzothiazole, 2-mercapto-benzothiazole, etc. Examples include benzothiazole rust preventive agents; and thiocarbamic acid derivative rust preventive agents having a similar structure. The concentration of the rust inhibitor in the etching solution composition generally ranges from 0.001 to 10% by weight.

As the solvent, alcohol solvents, ketone solvents, ether solvents, etc. can be used. Examples of alcoholic solvents include methanol, ethanol, diethylene glycol, isopropyl alcohol, and 2-ethylhexanol. Examples of the ketone solvent include methyl acetate, ethyl acetate, and propyl acetate. Examples of the ether solvent include tetrahydrofuran and methyl cellosolve.

An etching method according to an embodiment of the present invention includes etching a copper-based layer using the above-described etching solution composition (this composition). This etching method can employ steps of well-known general etching methods, except for using the above-mentioned etching liquid composition. Examples of the copper-based layer to be etched include copper alloys such as silver-copper alloys, aluminum-copper alloys, and copper-nickel alloys; and layers containing copper (metallic copper). Among these, copper is particularly suitable. As a specific etching method, for example, a dipping method, a spray method, etc. can be adopted. Etching conditions may also be adjusted as appropriate depending on the composition of the etching solution composition used and the etching method. Furthermore, various well-known methods such as a batch method, a flow method, and an auto-control method based on the oxidation-reduction potential, specific gravity, and acid concentration of the etchant may be employed.

Etching conditions are not particularly limited, and can be arbitrarily set depending on the shape and film thickness of the object to be etched. For example, it is preferable to spray the etching liquid composition at 0.01 to 0.2 MPa, more preferably 0.01 to 0.1 MPa. Further, the etching temperature is preferably 10 to 50°C, more preferably 20 to 50°C. Since the temperature of the etching liquid composition may rise due to the heat of reaction, the temperature may be controlled by known means to maintain it within the above temperature range, if necessary. The etching time may be set to a time that allows the object to be etched to be sufficiently etched. For example, when etching an object to be etched with a film thickness of about 30 μm, a line width of about 40 μm, and an opening of about 20 μm in the above temperature range, the etching time may be about 10 to 300 seconds.

According to the etching method using the above etching liquid composition, a fine pattern with excellent dimensional accuracy can be formed with good productivity. More specifically, when etching a copper-based layer using the above etching solution composition to form a thin wire, etching of the side (side surface) in the cross section of the thin wire is suppressed, and the etching width on one side is small. patterns can be formed with high productivity. Therefore, in addition to printed wiring boards, it can be suitably used in subtractive methods for package substrates, COFs, and TABs that require fine pitches.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples, but the present invention is not limited by these.

Comparative compounds 1 to 3 shown in the following chemical formulas (b1) to (b3), respectively, were prepared as comparative components of component (B). "nBu" in the following chemical formulas (b1) and (b3) represents a normal butyl group, and "Me" in the following chemical formula (b2) represents a methyl group.

<Example 1 (Examples 1-1 to 1-13) and Comparative Example 1 (Comparative Examples 1-1 to 1-7)>
Etching solution composition No. 1 was prepared by mixing copper (II) chloride, hydrogen chloride, component (B) or its comparative component, and water so as to have the composition shown in Table 1. I got a score of 1-20. Note that only in Examples 1-13, copper (II) sulfate was used as the cupric ion supply source. In addition, the component (B) has the chemical formula No. 1.No. 7.No. 8, No. 10, No. Table 1 shows the chemical formula No. 20 of the component (B) used. showed that. Moreover, the balance in the composition of the etching solution composition shown in Table 1 is water.

<Example 2 (Examples 2-1 to 2-13) and Comparative Example 2 (Comparative Examples 2-1 to 2-7)>
A substrate was prepared in which copper foil with a thickness of 35 μm was laminated on a resin substrate made of glass epoxy. A test board was prepared by forming a photoresist pattern with a line width of 38 μm and an opening of 22 μm on the copper foil of this base. The prepared test substrate was etched using the prepared etching solution composition under conditions of a processing temperature of 45° C. and a processing pressure of 0.1 MPa until the width of the lower part of the thin wire in the cross section of the thin wire was 30 μm. . Thereafter, the resist pattern was removed using a stripping solution to form a pattern (thin line).

<Evaluation>
The following (1) etching treatment time and (2) one side side etch width were evaluated. The evaluation results are shown in Table 2. Note that a short etching treatment time means that thin lines can be formed with high productivity. Furthermore, the smaller the side etching width on one side, the more suppressed the side etching. A cross-sectional view schematically showing the test substrate after etching is shown in FIG.

(1) Etching processing time The unit is "seconds".
(2) One side side etch width As shown in Figure 1, by observing the cross section of the test board after etching using a laser microscope, the line width 6 of the resist 2 and the etched copper foil 1 (thin line) were determined. In the cross section, the width on the resist 2 side (width 4 at the top of the thin line), which was smaller than the width on the resin substrate 3 side (width 5 at the bottom of the thin line), was measured. Then, the one side side etch width was calculated from the following formula. The unit is "μm".
"Single side etch width" = {"Resist line width" - "Measurement value of the width of the upper part of the thin line"}/2

As shown in Table 2, in Examples 2-1 to 2-13, the etching time was 55 seconds or less, indicating that patterns could be formed with good productivity. In particular, in Examples 2-5 to 2-7 and Examples 2-10 to 2-12, the etching time was 45 seconds or less, indicating that patterns could be formed with particularly high productivity. In addition, since the etching time was 40 seconds in Example 2-11, and 55 seconds in Example 2-13, the composition contained chloride ions. Furthermore, it can be seen that patterns can be formed with high productivity. On the other hand, in Comparative Examples 2-1, 2-4, and 2-5, the etching processing time was 65 seconds or more, and compared to Examples 2-1 to 2-13, patterns could not be formed with good productivity. Recognize. Furthermore, in Comparative Examples 2-2, 2-3, 2-6, and 2-7, the etching process could not be performed because Comparative Compound 1 or Comparative Compound 3 was not dissolved.

Further, as shown in Table 2, in Examples 2-1 to 2-13, the side etch width on one side was 11.6 μm or less, indicating that fine patterns with excellent dimensional accuracy could be formed. In particular, in Examples 2-5 to 2-7 and Examples 2-10 to 2-13, the side etch width on one side was 9.8 μm or less, and fine patterns with particularly excellent dimensional accuracy could be formed. I understand that. On the other hand, in Comparative Examples 2-1, 2-4, and 2-5, the side etch width on one side was 12.8 μm or more, and compared to Examples 2-1 to 2-13, fine patterns with excellent dimensional accuracy were obtained. It turns out that it could not be formed.

From the above results, according to this example, an etching solution composition and an etching method for a copper-based layer that can form a fine pattern with a small side etch width and desired dimensional accuracy with high productivity are provided. It turns out that it is possible to provide. Furthermore, it has been found that the effects of the present invention are specifically achieved when an ammonium compound having a specific structure is used as component (B).

1: Copper foil 2: Resist 3: Resin base 4: Width of upper part of fine line 5: Width of lower part of fine line 6: Line width of resist

Claims (5)

(A) cupric ion 0.1 to 20% by mass,
(B) An etching liquid composition for a copper-based layer containing 0.01 to 5% by mass of an ammonium compound represented by the following general formula (1) and water.

(In the general formula (1), R ¹ represents a phenyl group or a benzyl group, R ² to R ⁴ each independently represent an alkyl group having 1 to 3 carbon atoms, and X is a chlorine atom or a bromine atom. (represents an atom ) Contains chloride ions,
The etching solution composition for a copper-based layer according to claim 1, wherein the chloride ion concentration is 0.1 to 30% by mass. The etching solution composition for a copper-based layer according to claim 1 or 2, wherein the mass ratio of the component (B) to the component (A) is (B)/(A) = 0.01 to 1. The component (B) is selected from the group consisting of N-benzyltrimethylammonium chloride, N-benzyltrimethylammonium bromide, N-benzyltriethylammonium chloride, N-benzyltriethylammonium bromide, trimethylphenylammonium chloride, and trimethylphenylammonium bromide. The etching solution composition for a copper-based layer according to any one of claims 1 to 3 , comprising at least one of: An etching method comprising etching a copper-based layer using the etchant composition for a copper-based layer according to any one of claims 1 to 4 .

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