TWI860984B - Etching composition and etching method - Google Patents

Abstract

The etching composition provided by the present invention can form fine patterns with excellent dimensional accuracy while suppressing the occurrence of residual film, and can be used for etching metal layers such as copper-based layers. The etching composition of the present invention comprises: (A) 0.1-25% by mass of at least one component selected from copper (II) ions and iron (II) ions; (B) 0.1-30% by mass of chloride ions; (C) 0.01-10% by mass of a compound represented by the following general formula (1) (R ¹ : single bond, etc.; R ² and R ³ : straight chain or branched alkylene group having 1-4 carbon atoms; R ⁴ and R ⁵ : hydrogen atom, etc.; n: a number such that the number average molecular weight of the compound represented by the general formula (1) becomes 550-1,400) and having a number average molecular weight of 550-1,400; and an aqueous solution of water; wherein the mass ratio of the chloride ions (B) to the component (A) is (B)/(A)=0.5-2.

Description

Etching composition and etching method

The present invention relates to an etching composition containing a specific structural compound and an etching method using the same.

The circuit formation methods for printed circuit boards, semiconductor package substrates, etc. are known to include: the addition method of adding circuit patterns to the substrate afterwards, and the removal method (etching method) of removing unnecessary parts from the metal foil on the substrate to form the circuit pattern. At present, the removal method (etching method) with lower manufacturing cost is generally adopted in the manufacture of printed circuit boards. In addition, with the sophistication and miniaturization of electronic devices in recent years, the pattern of printed circuit boards is also required to be miniaturized, so the etching liquid that can form fine patterns on the substrate is developed.

For example, the etching solution disclosed in Patent Document 1 is an etching solution for copper or copper alloy containing: ferric chloride, oxalic acid and ethylenediaminetetrapolyoxyethylenepropylene. In addition, the etching solution for copper-containing materials disclosed in Patent Document 2 contains: ferric chloride (II), glycol ether compounds, ethylenediaminetetrapolyoxyethylenepropylene, phosphoric acid and hydrochloric acid.

[Prior Art Literature] [Patent Literature]

[Patent document 1] Japanese Patent Publication No. 2012-107286

[Patent Document 2] Japanese Patent Publication No. 2009-167459

However, the etching solution disclosed in the above patent document has problems such as difficulty in forming fine patterns with the required dimensional accuracy, or easily generating residual film that causes disconnection or short circuit.

Therefore, the present invention is completed to solve the above-mentioned problems, and the subject is to provide: a composition that can form a fine pattern with excellent dimensional accuracy while suppressing the occurrence of residual film, and can be used for etching of metal layers such as copper-based layers. In addition, the subject of the present invention is to provide: an etching method using the above-mentioned composition.

The inventors of this case conducted in-depth research to solve the above problems and found that a composition containing specific ingredients can solve the above problems, thus completing this invention.

That is, the composition provided by the present invention contains: (A) 0.1-25% by mass of at least one component selected from copper (II) ions and iron (II) ions; (B) 0.1-30% by mass of chloride ions; (C) 0.01-10% by mass of a compound having a number average molecular weight of 550-1,400 represented by the following general formula (1); and an aqueous solution of water; wherein the mass ratio of the above-mentioned (B) chloride ions to the above-mentioned (A) component is (B)/(A)=0.5-2.

(In the above general formula (1), ^R1 represents a single bond, or a linear or branched alkylene group having 1 to 4 carbon atoms; ^R2 and ^R3 each independently represent a linear or branched alkylene group having 1 to 4 carbon atoms; ^R4 and ^R5 each independently represent a hydrogen atom, or a linear or branched alkylene group having 1 to 4 carbon atoms; n each independently represents a value such that the number average molecular weight of the compound represented by the above general formula (1) is 550 to 1,400)

Furthermore, according to the present invention, an etching method is provided, which includes: using the above-mentioned composition to perform etching.

According to the present invention, a composition can be provided that can form a fine pattern with excellent dimensional accuracy while suppressing the occurrence of residual film, and can be used for etching of metal layers such as copper-based layers. In addition, according to the present invention, an etching method using the above composition can be provided.

1‧‧‧Copper foil

2‧‧‧Photoresist

3‧‧‧Resin matrix

4‧‧‧Width of upper part of thin line

5‧‧‧Width of lower part of fine line

6‧‧‧Photoresist line width

Figure 1 is a schematic cross-sectional view of the test substrate after etching.

The following is a detailed description of the embodiments of the present invention. The composition of the present invention contains essential components: (A) at least one component selected from copper (II) ions and iron (II) ions (hereinafter also referred to as "(A) component"); (B) chloride ions (hereinafter also referred to as "(B) component"); (C) a compound represented by general formula (1) (hereinafter also referred to as "(C) component"); and an aqueous solution of water. The composition of the present invention is suitable as an etching liquid composition for etching a metal layer such as a copper-based layer. The copper-based layer may include, for example, a copper alloy such as a silver-copper alloy and an aluminum-copper alloy; and a layer of copper, etc. Among them, the composition of the present invention is suitable as an etching liquid composition for etching a copper-containing copper-based layer.

Component (A) can be copper (II) ions and iron (II) ions used alone or in combination. By adding a copper (II) compound, the composition can contain copper (II) ions. That is, the copper (II) compound can be used as a supply source of copper (II) ions. In addition, by adding an iron (III) compound, the composition can contain iron (II) ions. That is, the iron (III) compound can be used as a supply source of iron (II) ions.

Examples of copper (II) compounds include copper (II) chloride, copper (II) bromide, copper (II) sulfate, and copper (II) hydroxide. Examples of iron (III) compounds include iron (III) chloride, iron (III) bromide, iron (III) iodide, iron (III) sulfate, iron (III) nitrate, and iron (III) acetate. Among these compounds, copper (II) chloride and iron (III) chloride are preferred, and copper (II) chloride is more preferred. These compounds can be used alone or in combination of two or more.

The concentration of component (A) in the composition of the present invention is 0.1-25% by mass, preferably 0.5-23% by mass, and more preferably 1-20% by mass. The concentration of component (A) can be appropriately adjusted according to the thickness and width of the etched object. The concentration of component (A) refers to the concentration of copper (II) ions or the concentration of iron (II) ions when copper (II) ions or iron (II) ions are used alone. In addition, when copper (II) ions and iron (II) ions are used in combination (mixed), it refers to the total concentration of copper (II) ions and iron (II) ions. For example, when copper (II) chloride contains 10 mass%, the concentration of component (A) is about 4.7 mass%. Also, when copper (II) chloride contains 10 mass% and iron (III) chloride contains 10 mass%, the concentration of component (A) is about 8.2 mass%. In addition, the concentration of iron (II) ions is preferably less than 5 mass%.

The supply source of component (B) can be, for example, hydrogen chloride, sodium chloride, calcium chloride, potassium chloride, barium chloride, ammonium chloride, iron (III) chloride, copper (II) chloride, manganese (II) chloride, cobalt (II) chloride, barium (III) chloride, and zinc (II) chloride. Among them, hydrogen chloride, iron (III) chloride, and copper (II) chloride are preferred, and hydrogen chloride is more preferred because the etching speed and the shape of the wiring pattern can be easily controlled.

The concentration of component (B) in the composition of the present invention is 0.1-30% by mass, preferably 0.5-28% by mass, and more preferably 1-25% by mass. The concentration of component (B) can be appropriately adjusted according to the thickness and width of the object to be etched. If the concentration of component (B) is less than 0.1% by mass, the etching speed may be insufficient. On the other hand, even if the concentration of component (B) exceeds 30% by mass, it is still difficult to further increase the etching speed, and it is easy to cause undesirable conditions such as corrosion of device components.

In the composition of the present invention, the mass ratio of component (B) to component (A) is (B)/(A) = 0.5~2, preferably 0.6~1.8, more preferably 0.65~1.7, and particularly preferably 0.7~1.4. If the (B)/(A) value exceeds 2, it will not be possible to form a fine wiring pattern with excellent dimensional accuracy. On the other hand, if the (B)/(A) value is less than 0.5, the etching speed is insufficient.

Component (C) is a compound having a number average molecular weight of 550 to 1,400 represented by the following general formula (1).

(In the above general formula (1), ^R1 represents a single bond, or a linear or branched alkylene group having 1 to 4 carbon atoms; ^R2 and ^R3 each independently represent a linear or branched alkylene group having 1 to 4 carbon atoms; ^R4 and ^R5 each independently represent a hydrogen atom, or a linear or branched alkylene group having 1 to 4 carbon atoms; n each independently represents a value such that the number average molecular weight of the compound represented by the above general formula (1) is 550 to 1,400)

Examples of the linear or branched alkylene groups having 1 to 4 carbon atoms represented by ^R1 , ^R2 and ^R3 include methylene, ethylene, propylene, methylethylene, butylene, ethylethylene, 1-methylpropylene and 2-methylpropylene. Examples of the linear or branched alkylene groups having 1 to 4 carbon atoms represented by ^R4 and ^R5 include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl and tert-butyl.

From the viewpoint of easy control of etching rate and easy suppression of side etching, the component (C) is preferably a compound in which R ¹ in the general formula (1) is an ethylidene group, R ² and R ³ are methylethylidene groups, R ⁴ and R ⁵ are hydrogen atoms, and the number average molecular weight is 650 to 1,300. The number average molecular weight of the component (C) is more preferably 750 to 1,200.

Preferred specific examples of the compound represented by general formula (1) include compounds represented by the following chemical formulas No. 1 to No. 36. In the following chemical formulas No. 1 to No. 36, "Me" represents a methyl group, "Et" represents an ethyl group, and "iPr" represents an isopropyl group. In addition, n is a value that independently represents a number average molecular weight of the compound represented by chemical formula No. 1 to No. 36 of 550 to 1,400.

The method for producing component (C) is not particularly limited, and it can be produced by applying a known reaction. For example, ethylenediamine and propylene oxide are used as raw materials and produced according to the reaction shown in the following formula (2). "Me" in the following formula (2) represents a methyl group.

The concentration of the component (C) in the composition of the present invention is 0.01-10% by mass, preferably 0.05-8% by mass, and more preferably 0.1-5% by mass. If the concentration of the component (C) is less than 0.01% by mass, the desired effect caused by the addition of the component (C) cannot be obtained. On the other hand, if the concentration of the component (C) exceeds 10% by mass, when the composition of the present invention is used as an etching liquid composition, it is easy to cause a decrease in the etching speed. In addition, the etching liquid composition is easy to penetrate at the interface between the metal layer such as the copper layer and the photoresist, which is easy to cause poor pattern shape.

The composition of the present invention is water containing essential components and an aqueous solution in which each component is dissolved in water. The water is preferably ion-exchange water, pure water, ultrapure water, etc., water from which ionic substances and impurities have been removed.

The composition of the present invention is suitable as, for example, an etchant composition (etching solution) for etching a metal layer such as a copper-based layer, an additive for electroless plating solution, an additive for metal electrolytic refining, a pesticide, and an insecticide. It is particularly preferred to use it as an etchant composition for etching a metal layer.

When the composition of the present invention is an etching liquid composition, the components other than component (A), component (B), component (C) and water in the etching liquid composition may also be mixed with known additives within the range that does not impair the effect of the present invention. Additives include, for example, stabilizers of the etching liquid composition, solubilizers of each component, defoamers, pH adjusters, specific gravity adjusters, viscosity adjusters, wettability improvers, chelating agents, oxidants, reducing agents, surfactants, etc. The concentrations of these additives can be set within the range of 0.001~50% by mass.

等氫氧化四級銨類；乙胺、二乙胺、三乙胺、羥乙胺等有機胺類；碳酸氫銨；氨等。該等pH調節劑係可單獨使用一種、或組合使用二種以上。pH調節劑的含有量係設為蝕刻液組成物的pH成為所需pH的量即可。 Examples of pH adjusters include: inorganic acids such as sulfuric acid and nitric acid and their salts; water-soluble organic acids and their salts; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali earth metal hydroxides such as calcium hydroxide, strontium hydroxide, and barium hydroxide; alkali metal carbonates such as ammonium carbonate, lithium carbonate, sodium carbonate, and potassium carbonate; alkali metal bicarbonates such as sodium bicarbonate and potassium bicarbonate; tetramethylammonium hydroxide, bicarbonate, and tetramethyleneimine hydroxide.

Quaternary ammonium hydroxides; organic amines such as ethylamine, diethylamine, triethylamine, hydroxyethylamine; ammonium bicarbonate; ammonia, etc. These pH adjusters can be used alone or in combination of two or more. The amount of the pH adjuster is set to an amount that the pH of the etching solution composition becomes the desired pH.

Chelating agents include, for example, aminocarboxylic acid chelating agents such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, tetraethylenepentaamineheptaacetic acid, pentaethylenehexamineoctaacetic acid, nitrilotriacetic acid, and their alkali metal (preferably sodium) salts; hydroxyethylenediphosphonic acid, nitrilotrimethylenephosphonic acid, phosphonobutanetricarboxylic acid, and their alkali metal salts. Phosphonic acid chelating agents such as (preferably sodium) salts; divalent or higher carboxylic acid compounds such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, fumaric acid, apple acid, tartaric acid, citric acid, their anhydrates, and their alkali metal (preferably sodium) salts; and monoanhydrides and dianhydrides dehydrated from divalent or higher carboxylic acid compounds. The concentration of the chelating agent in the etching solution composition is generally in the range of 0.01-40 mass %, preferably in the range of 0.05-30 mass %.

啉鎓鹽、聚氧乙烯烷基(烯基)胺、烷基(烯基)胺鹽、聚胺脂肪酸衍生物、戊醇脂肪酸酯衍生物、氯化苯二甲烴銨、苄索氯銨等。兩性界面活性劑係可舉例如：羧基甜菜

、磺甜菜

、磷酸甜菜

、醯胺胺基酸、咪唑鎓甜菜

系界面活性劑等。蝕刻液組成物中的界面活性劑之濃度，一般係0.001~10質量%範圍。 Examples of the surfactant include nonionic surfactants, cationic surfactants, and amphoteric surfactants. Examples of non-ionic surfactants include polyoxyalkylene ethers, polyoxyalkylene alkenyl ethers, polyoxyethylene polyoxypropylene ethers (the addition form of ethylene oxide and propylene oxide may be either random or block), polyethylene glycol propylene oxide adducts, polypropylene glycol ethylene oxide adducts, glycerol fatty acid esters and ethylene oxide adducts; sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, alkyl polyglucosides, fatty acid monoethanolamides and ethylene oxide adducts; fatty acid-N-methyl monoethanolamides and ethylene oxide adducts; fatty acid diethanolamides and ethylene oxide adducts; sucrose fatty acid esters, alkyl (poly)glycerol ethers, polyglycerol fatty acid esters, polyethylene glycol fatty acid esters, fatty acid methyl ester ethoxylates, N-long chain alkyl dimethyl amine oxides, etc. Examples of cationic surfactants include alkyl (alkenyl) trimethylammonium salts, dialkyl (alkenyl) dimethylammonium salts, alkyl (alkenyl) quaternary ammonium salts, mono- or di-alkyl (alkenyl) quaternary ammonium salts containing ether groups, ester groups or amide groups; alkyl (alkenyl) pyridinium salts, alkyl (alkenyl) dimethylbenzylammonium salts, alkyl (alkenyl) isoquinolinium salts, dialkyl (alkenyl)

Phosphinium salts, polyoxyethylene alkyl (alkenyl) amines, alkyl (alkenyl) amine salts, polyamine fatty acid derivatives, amyl alcohol fatty acid ester derivatives, amyl chloride, benzethonium chloride, etc. Amphoteric surfactants include carboxy betaine.

, Sulphur Beet

, beet phosphate

, amide amino acid, imidazolium beet

Surfactants, etc. The concentration of surfactants in the etching solution composition is generally in the range of 0.001~10 mass%.

The etching method of the present invention includes: the step of etching using the composition of the present invention (etching liquid composition). In addition to using the above-mentioned etching liquid composition, the etching method of the present invention can adopt the steps of the known general etching method. The etched object is in the metal layer, preferably a copper-based layer. The copper-based layer can be, for example, a layer containing: a copper alloy such as a silver-copper alloy, an aluminum-copper alloy; and copper, etc. Among them, copper is more preferred. The specific etching method can be, for example, an immersion method, a spray method, etc. The relevant etching conditions can be appropriately adjusted in accordance with the composition of the etching liquid composition used and the etching method. In addition, various well-known methods such as batch method, flow method, and automatic control method using the redox potential or specific gravity of the etching solution and acid concentration can also be adopted.

There is no particular limitation on the etching conditions, and they can be set arbitrarily according to the shape and film thickness of the object to be etched. For example, it is preferred to spray the etching liquid composition at 0.01~0.2MPa, and more preferably at 0.01~0.1MPa. In addition, the etching temperature is preferably 10~50℃, and more preferably 20~50℃. Because the temperature of the etching liquid composition rises due to the reaction heat, the temperature can be controlled by known means as needed to maintain it within the above temperature range. The etching time can be set to a time that the object to be etched can be fully etched. For example, for an object to be etched with a film thickness of about 1μm, a line width of about 10μm, and an opening of about 100μm, when etching is performed within the above temperature range, the etching time only needs to be set to about 10~300 seconds.

According to the etching method using the etching liquid composition of the present invention, a fine pattern can be formed while suppressing the generation of residual film. Therefore, in addition to printed circuit boards, it can also be applied to the removal method for packaging substrates, COF, and TAB applications that require fine spacing.

[Implementation example]

The present invention is described in detail below using embodiments and comparative examples, but the present invention is not limited thereto.

The number average molecular weight of the component (C) used in the Examples and Comparative Examples is shown in Table 1. C-1 to C-4 in Table 1 are compounds represented by Chemical Formula No. 17, and n in Chemical Formula No. 17 is a value that makes the number average molecular weight of the compound represented by Chemical Formula No. 17 the value shown in Table 1. In addition, C-5 and C-6 in Table 1 are compounds represented by the following general formula (3):

(In the above general formula (3), ^R11 represents an ethylene group; ^R12 and ^R13 represent a methylethylene group; ^R14 and ^R15 represent an ethylene group; ⁿ¹ and ⁿ² represent values such that the number average molecular weight of the compound represented by the above general formula (3) becomes the value shown in Table 1. Wherein, ⁿ¹ /( ⁿ¹ + ⁿ² )=0.2)

(Example 1 and Comparative Example 1)

Copper chloride (II), hydrochloric acid and component (C) are mixed in a manner to form the composition shown in Table 2 to obtain etching solution compositions No. 1 to 21. In addition, the remainder of the etching solution compositions is water.

(Example 2 and Comparative Example 2)

A substrate with 8μm thick copper foil layered on a resin substrate was prepared. A dry film photoresist with a line width of 14μm and an opening of 6μm was formed on the copper foil of the substrate to prepare a test substrate. For the prepared test substrate, the prepared etching liquid composition was used to perform wet etching with spraying for a suitable etching time (50~130 seconds) at a processing temperature of 45℃ and a processing pressure of 0.1MPa. The so-called "just etching time" refers to the time calculated from the etching speed until the lower width of the fine line becomes 10μm. Then, the photoresist pattern was removed using a stripping liquid to form a fine pattern (fine line).

The formed fine lines were evaluated in the following items (1) to (5). The evaluation results are shown in Table 3. In addition, the smaller the unilateral side etching width is, the more suppressed the side etching is. In addition, the absence of residual film (residue of the etched part) means that line breakage and short circuit are less likely to occur. A schematic cross-sectional view of the test substrate after etching is shown in Figure 1.

(1) Width of the upper part of the thin line

Cross-section observation and measurement are performed using a laser microscope. The unit is "μm".

(2) Width of the lower part of the fine line

Cross-section observation and measurement are performed using a laser microscope. The unit is "μm".

(3) The difference between the width of the lower part of the thin line and the width of the upper part of the thin line

Calculated by the following formula. The unit is "μm".

"Difference between thin line lower width and thin line upper width" = "thin line lower width measurement value" - "thin line upper width measurement value"

(4) Single-sided etching width

Calculated by the following formula. The unit is "μm".

"Single-side etching width" = {"Photoresist line width" - "Measured value of the upper width of the thin line"}/2

(5) Whether there is residual film

Using a laser microscope, the samples where the etched residue was observed were marked as "yes", and the samples where it was not observed were marked as "no".

As shown in Table 3, compared with Comparative Examples 2-1, 2-2, and 2-5 to 2-10, Examples 2-1 to 2-11 can maintain the upper width of the thin line, and the difference between the lower width of the thin line and the upper width of the thin line is small, and the unilateral etching width is also small. In particular, in Examples 2-1 to 2-3, 2-6 to 2-8, and 2-10, the difference between the lower width of the thin line and the upper width of the thin line is less than 2.0 μm, and a pattern with high dimensional accuracy is formed. On the other hand, in Comparative Examples 2-3 and 2-4, the etching speed is insufficient, so the pattern is not formed, and the evaluation items (1) to (4) cannot be measured. From the results of Examples 2-1 to 2-11 and Comparative Examples 2-1 to 2-4, it is known that even when etching is performed using a composition containing a compound represented by general formula (1), if the (B)/(A) value of the composition exceeds a specific range, the dimensional accuracy is reduced or the pattern cannot be formed. In addition, no residual film (residue of the etched part) was observed in Examples 2-1 to 2-11 and Comparative Examples 2-5 and 2-6, while residual film was observed in Comparative Examples 2-1 to 2-4 and 2-7 to 2-10. As described above, according to the present invention, it is possible to provide an etching composition and an etching method that are not prone to the generation of residual film that causes disconnection and short circuits and can form fine patterns with the required dimensional accuracy.

Claims (6)

A composition for etching, comprising an aqueous solution of: (A) 1-25% by mass of at least one component selected from copper (II) ions and iron (II) ions; (B) 1-30% by mass of chloride ions; (C) 0.1-5% by mass of a compound having a number average molecular weight of 550-1,400 represented by the following general formula (1); and water; the mass ratio of the chloride ions (B) to the component (A) is (B)/(A)=0.5-2;

(In the above general formula (1), ^R1 represents a single bond, or a linear or branched alkylene group having 1 to 4 carbon atoms; ^R2 and ^R3 each independently represent a linear or branched alkylene group having 1 to 4 carbon atoms; ^R4 and ^R5 each independently represent a hydrogen atom, or a linear or branched alkylene group having 1 to 4 carbon atoms; n each independently represents a value that makes the number average molecular weight of the compound represented by the above general formula (1) 550 to 1,400). The etching composition of claim 1, wherein in the general formula (1), R ² and R ³ are methyl ethylidene groups. The etching composition of claim 1 or 2 is an etching liquid composition used for etching a metal layer. As in claim 3, the etching composition, wherein the metal layer is a copper-based layer. An etching method includes: using the composition of claim 3 to perform etching. An etching method includes: using the composition of claim 4 to perform etching.

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