JP7731346B2 - How to clean a substrate - Google Patents

Description

This disclosure relates to a cleaning composition for removing resin masks, a method for cleaning substrates using the same, and a method for manufacturing electronic components.

In recent years, personal computers and various electronic devices have become increasingly power-efficient, faster, and more compact, and the wiring on package substrates and other devices used in these devices has become increasingly finer with each passing year. Until now, metal masking has primarily been used to form such fine wiring and connection terminals such as pillars and bumps, but due to its limited versatility and the difficulty of adapting to the miniaturization of wiring, new methods are being adopted.

One new method is to use a dry film resist as a thick resin mask instead of a metal mask. This resin mask is eventually peeled off and removed, and a known cleaning agent for peeling off the resin mask contains an alkaline agent and water.

For example, Japanese Patent Application Laid-Open No. 2014-78009 (Patent Document 1) describes a composition containing an alkanolamine, an organic solvent, water, a hydroxide, and a corrosion inhibitor as a composition that is effective in effectively removing a thick film resist without damaging the substrate structure underneath the film resist.
Japanese Patent Laid-Open Publication No. 2015-79244 (Patent Document 2) describes a cleaning composition for resin mask layers that contains a specific quaternary ammonium hydroxide, a water-soluble amine, an acid or an ammonium salt thereof, and water, as a cleaning agent that can both promote removal of a resin mask layer after heat treatment of solder bumps and suppress solder corrosion, thereby improving solder connection reliability.

In one aspect, the present disclosure relates to a method for ^cleaning a substrate, the method comprising _the step of stripping a resin mask from a substrate having a copper-containing metal layer and a resin mask on its surface, using a cleaning composition containing an alkaline agent (component A), ammonium ions (NH 4 + , component B), thioglycolic acid (component C), and water (component D), wherein the molar ratio of component B to component C (B/C) is 1.5 or more.

In one aspect, the present disclosure relates to a method for manufacturing an electronic component, which includes a step of stripping a resin mask from a substrate having a copper-containing metal layer and a resin mask on its surface using the cleaning method of the present disclosure.

In one aspect, the present disclosure relates to a cleaning composition for removing resin masks, which contains an alkaline agent (component A), ammonium ions (NH ₄ ⁺ , component B), thioglycolic acid (component C), and water (component D), and the molar ratio of component B to component C (B/C) is 1.5 or more.

In one aspect, the present disclosure relates to the use of a cleaning composition containing an alkaline agent (component A), ammonium ions (NH ₄ ⁺ , component B), thioglycolic acid (component C), and water (component D), wherein the molar ratio of component B to component C (B/C) is 1.5 or more, for cleaning a substrate having a copper-containing metal layer and a resin mask on its surface.

When forming fine wiring on printed circuit boards and the like, a cleaning composition is required to have high cleaning performance in order to reduce not only the residue of the resin mask but also the residue of auxiliary agents contained in the solder and plating solution used in forming the fine wiring and bumps.
Here, a resin mask is formed using a resist whose physical properties, such as solubility in a developer, change when exposed to light or an electron beam. Resists are broadly divided into negative and positive types based on how they react with light or an electron beam. Negative resists have the property of decreasing solubility in a developer when exposed to light. A layer containing a negative resist (hereinafter also referred to as a "negative resist layer") has the exposed portion used as a resin mask after exposure and development. Positive resists have the property of increasing solubility in a developer when exposed to light. A layer containing a positive resist (hereinafter also referred to as a "positive resist layer") has the exposed portion removed after exposure and development, and the unexposed portion used as a resin mask. Using a resin mask with these properties allows for the formation of fine connections on circuit boards, such as metal wiring, metal pillars, and solder bumps. The resin mask must be removed after the formation of the fine wiring or bumps.

However, as wiring becomes finer, it becomes more difficult to remove resin masks from tiny gaps, and cleaning compositions are required to have high resin mask removal properties. Furthermore, corrosion and tarnish of copper, which is used in many wiring and connection terminals, can reduce the quality and value of package substrates, so cleaning compositions are required to have high corrosion and tarnish prevention capabilities. Copper tarnish is known to occur, for example, due to the formation of sulfides on the copper surface, and it is difficult to remove tarnished copper when a copper removal process (e.g., a seed etch process) is performed after the cleaning process.

Therefore, in one aspect, the present disclosure provides a substrate cleaning method and a cleaning composition for removing resin masks that have excellent resin mask removal properties and can suppress copper corrosion and discoloration.

This disclosure is based on the discovery that by using a cleaning composition containing ammonium ions and thioglycolic acid in a specific molar ratio, resin masks can be efficiently removed from substrate surfaces while suppressing copper corrosion.

In one aspect, the present disclosure relates to a method for cleaning a substrate ( _hereinafter also referred to as the " ^cleaning method of the present disclosure"), which includes a step of stripping a resin mask from a substrate having a copper-containing metal layer and a resin mask on its surface, using a cleaning composition (hereinafter also referred to as the "cleaning composition of the present disclosure") containing an alkaline agent (component A), ammonium ions (NH 4 + , component B), thioglycolic acid (component C), and water (component D), in which the molar ratio of component B to component C (B/C) is 1.5 or more.

The present disclosure provides a cleaning method that is excellent at removing resin masks and can suppress copper corrosion and discoloration. Furthermore, by using the cleaning method of the present disclosure, high-quality electronic components can be obtained with a high yield. Furthermore, by using the cleaning method of the present disclosure, electronic components with fine wiring patterns can be efficiently manufactured.

Although the details of the mechanism of action by which the effects of the present disclosure are manifested are still unclear, it is presumed as follows.
It is believed that alkaline agents penetrate into the resin mask, promoting dissociation of the alkali-soluble resin contained in the resin mask, and further promoting the peeling of the resin mask by causing the repulsion of charges generated by the dissociation, thereby improving the removability of the resin mask. On the other hand, alkaline agents are believed to be involved in copper etching (corrosion). Thioglycolic acid can inhibit copper etching by alkaline agents, but it is believed to form a salt with copper, causing copper discoloration. In a cleaning composition containing water, by combining ammonium ions and thioglycolic acid at a specific ratio, the ammonium ions present in excess of thioglycolic acid suppress the formation of copper salts of thioglycolic acid, and it is believed that in the presence of alkaline agents, copper etching (corrosion) and good stripping performance can be inhibited, while copper discoloration can be suppressed.
However, the present disclosure need not be construed as being limited to this mechanism.

In the present disclosure, the resin mask to be peeled off and removed is a mask that protects the surface of a material from processes such as etching, plating, and heating, i.e., a mask that functions as a protective film. In one or more embodiments, the resin mask may be a resist layer after exposure and development processes, a resist layer that has been subjected to at least one of exposure and development (hereinafter also referred to as "exposed and/or developed"), or a hardened resist layer. In one or more embodiments, the resin material that forms the resin mask may be a film-like photosensitive resin, a resist film, or a photoresist. General-purpose resist films can be used.

[Cleaning composition]
In one or more embodiments, the cleaning composition of the present disclosure is a cleaning composition for removing resin masks, which contains an alkaline agent (component A), ammonium ions (component B), thioglycolic acid (component C), and water (component D), and the molar ratio of component B to component C (B/C) is 1.5 or more. In one or more embodiments, the cleaning composition of the present disclosure can suppress copper discoloration while inhibiting copper corrosion and exhibiting good resin mask removal performance. In one or more embodiments, the cleaning composition of the present disclosure can efficiently peel and remove resin masks present in fine gaps. In one or more embodiments, the cleaning composition of the present disclosure can suppress damage to substrate resins. An example of a substrate resin is solder resist.

[Alkaline agent (component A)]
In one or more embodiments, the alkaline agent (hereinafter also simply referred to as "Component A") contained in the cleaning composition of the present disclosure is at least one selected from inorganic alkalis and organic alkalis, and from the viewpoint of reducing the load on wastewater treatment, inorganic alkalis are preferred. Component A may be used alone or in combination of two or more types.

In one or more embodiments, the inorganic alkali may be a hydroxide, carbonate, or silicate of an alkali metal or alkaline earth metal, and specifically may be at least one selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, and potassium silicate. Among these, from the viewpoint of improving resin mask removability, one or a combination of two or more selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate is preferred, with at least one of sodium hydroxide and potassium hydroxide being more preferred, and potassium hydroxide being even more preferred. In the present disclosure, inorganic alkali does not include ammonia ( _NH3 ) or ammonium ion ( _NH4 ⁺ ).

In one or more embodiments, examples of the organic alkali include tetraalkylammonium hydroxide and organic amine. Examples of the tetraalkylammonium hydroxide include quaternary ammonium hydroxide represented by the following formula (I). Examples of the organic amine include amine represented by the following formula (II). In one or more embodiments, from the viewpoint of improving resin mask removability, it is preferable to use a combination of a quaternary ammonium hydroxide represented by formula (I) and an amine represented by formula (II) as component A.

In the above formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represent at least one group selected from the group consisting of a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, a hydroxyethyl group and a hydroxypropyl group.

In the above formula (II), ^R5 represents a hydrogen atom, a methyl group, an ethyl group, or an aminoethyl group; ^R6 represents at least one selected from a hydrogen atom, a hydroxyethyl group, a hydroxypropyl group, a methyl group, or an ethyl group; and ^R7 represents at least one selected from an aminoethyl group, a hydroxyethyl group, or a hydroxypropyl group; or, in formula (II), ^R5 represents at least one selected from a methyl group, an ethyl group, an aminoethyl group, a hydroxyethyl group, or a hydroxypropyl group; and ^R6 and ^R7 are bonded to each other to form a pyrrolidine ring or a piperazine ring together with the N atom in formula (II).

Examples of quaternary ammonium hydroxides represented by formula (I) include salts composed of a quaternary ammonium cation and a hydroxide. Specific examples of quaternary ammonium hydroxides include at least one selected from tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide (choline), 2-hydroxyethyltriethylammonium hydroxide, 2-hydroxyethyltripropylammonium hydroxide, 2-hydroxypropyltrimethylammonium hydroxide, 2-hydroxypropyltriethylammonium hydroxide, 2-hydroxypropyltripropylammonium hydroxide, dimethylbis(2-hydroxyethyl)ammonium hydroxide, diethylbis(2-hydroxyethyl)ammonium hydroxide, dipropylbis(2-hydroxyethyl)ammonium hydroxide, tris(2-hydroxyethyl)methylammonium hydroxide, tris(2-hydroxyethyl)ethylammonium hydroxide, tris(2-hydroxyethyl)propylammonium hydroxide, tetrakis(2-hydroxyethyl)ammonium hydroxide, and tetrakis(2-hydroxypropyl)ammonium hydroxide. Among these, from the viewpoint of improving the removability of the resin mask, tetramethylammonium hydroxide and tetraethylammonium hydroxide are preferred, and tetramethylammonium hydroxide is more preferred.

Examples of amines represented by formula (II) include alkanolamines, primary to tertiary amines, and heterocyclic compounds. Specific examples of amines include monoethanolamine, monoisopropanolamine, N-methylmonoethanolamine, N-methylisopropanolamine, N-ethylmonoethanolamine, N-ethylisopropanolamine, diethanolamine, diisopropanolamine, N-dimethylmonoethanolamine, N-dimethylmonoisopropanolamine, N-methyldiethanolamine, N-methyldiisopropanolamine, N-diethylmonoethanolamine, N-diethylmonoisopropanolamine, N-ethyldiethanolamine, N-ethyldiisopropanolamine, N-(β-aminoethyl)ethanolamine, N-(β-aminoethyl)isopropanolamine, N-(β-aminoethyl)diethanolamine, N-(β-aminoethyl)diisopropanolamine, 1-methylpiperazine, 1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)piperazine, ethylenediamine, and at least one selected from diethylenetriamine. Among these, from the viewpoint of improving the removability of the resin mask, monoethanolamine and diethanolamine are preferred, and monoethanolamine is more preferred.

The content of Component A when using the cleaning composition of the present disclosure is preferably 0.5% by mass or more, more preferably 2% by mass or more, from the viewpoints of improving resin mask removability and inhibiting copper corrosion. From the same viewpoints, it is preferably 8% by mass or less, more preferably 6% by mass or less. More specifically, the content of Component A when using the cleaning composition of the present disclosure is preferably 0.5% by mass or more and 8% by mass or less, more preferably 2% by mass or more and 6% by mass or less. When Component A is a combination of two or more types, the content of Component A refers to the total content of those types.

In this disclosure, the "content of each component of the cleaning composition at the time of use" refers to the content of each component at the time of cleaning, i.e., at the time when the cleaning composition begins to be used for cleaning.

[Ammonium ion: NH ₄ ⁺ (component B)]
The ammonium ion contained in the cleaning composition of the present disclosure (hereinafter also referred to as "component B") is an ammonium ion represented by the chemical formula NH ₄ ⁺ .
In one or more embodiments, the source of component B is not particularly limited as long as it is a compound that can supply ammonium ions (NH ₄ ⁺ ), but from the viewpoints of resin mask removability and copper corrosion inhibition, at least one of ammonia and an ammonium salt of an organic acid is used. Ammonia can be used in gaseous form, but from the viewpoint of workability, it is preferably used as an aqueous solution (aqueous ammonia). Examples of ammonium salts of organic acids include ammonium salts of thioglycolic acid (component C). From the viewpoints of resin mask removability and copper corrosion inhibition, the source of component B is preferably a combination of ammonia and an ammonium salt of thioglycolic acid (component C), or a combination of ammonia and an ammonium salt of a carboxylic acid.

When using the cleaning composition of the present disclosure, the content (mol/100g) of component B per 100g of the cleaning composition is preferably 0.02 mol/100g or more, more preferably 0.04 mol/100g or more, from the viewpoints of improving resin mask removability and inhibiting copper corrosion. From the same viewpoints, the content (mol/100g) of component B per 100g of the cleaning composition is preferably 0.08 mol/100g or less, more preferably 0.06 mol/100g or less. More specifically, when using the cleaning composition of the present disclosure, the content (mol/100g) of component B per 100g of the cleaning composition is preferably 0.02 mol/100g or more and 0.08 mol/100g or less, more preferably 0.04 mol/100g or more and 0.06 mol/100g or less.

[Thioglycolic acid (ingredient C)]
The source of thioglycolic acid (component C) in the cleaning composition of the present disclosure may be thioglycolic acid or a salt thereof. For example, an ammonium salt of thioglycolic acid may be a source of components B and C. For example, monoethanolamine thioglycolate may be a source of components A and C.

The content (mass %) of thioglycolic acid (hereinafter also referred to as "Component C") during use of the cleaning composition of the present disclosure is preferably 0.5% by mass or more, more preferably 1% by mass or more, from the viewpoints of improving resin mask removability and inhibiting copper corrosion, and from the same viewpoints, is preferably 3% by mass or less, more preferably 2% by mass or less. More specifically, the content of Component C during use of the cleaning composition of the present disclosure is preferably 0.5% by mass or more and 3% by mass or less, more preferably 1% by mass or more and 2% by mass or less.

When using the cleaning composition of the present disclosure, the content of component C (mol/100g) per 100g of the cleaning composition is preferably 0.005 mol/100g or more, more preferably 0.01 mol/100g or more, from the viewpoints of improving resin mask removability and inhibiting copper corrosion. From the same viewpoint, it is preferably 0.03 mol/100g or less, more preferably 0.02 mol/100g or less. More specifically, when using the cleaning composition of the present disclosure, the content of component C per 100g of the cleaning composition is preferably 0.005 mol/100g or more and 0.03 mol/100g or less, more preferably 0.01 mol/100g or more and 0.02 mol/100g or less.

The molar ratio of component B to component C (B/C) (content of component B/content of component C) in the cleaning composition of the present disclosure is 1.5 or greater, preferably 2 or greater, and more preferably 3 or greater, from the viewpoints of improving resin mask removability, inhibiting copper corrosion, and inhibiting copper tarnish. From the same viewpoints, it is preferably 5 or less, and more preferably 4 or less. More specifically, the molar ratio (B/C) is preferably 2 or greater and 5 or less, and more preferably 3 or greater and 4 or less.

[Water (component D)]
In one or more embodiments, examples of water (hereinafter also referred to as "component D") contained in the cleaning composition of the present disclosure include ion-exchanged water, RO water, distilled water, pure water, and ultrapure water.

The content of component D in the cleaning composition of the present disclosure can be the remainder excluding components A, B, C, and the optional components described below. Specifically, the content of component D during use of the cleaning composition of the present disclosure is preferably 45% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, from the viewpoints of improving resin mask removability, inhibiting copper corrosion, reducing the burden on wastewater treatment, and reducing the impact on substrates. From the viewpoint of improving resin mask removability, the content is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less. More specifically, the content of component D during use of the cleaning composition of the present disclosure is preferably 45% by mass or more but 99% by mass or less, more preferably 60% by mass or more but 98% by mass or less, and even more preferably 80% by mass or more but 97% by mass or less.

The total amount of components A, B, C, and D when using the cleaning composition of the present disclosure is preferably 60% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, from the viewpoints of improving resin mask removability and inhibiting copper corrosion.

[Organic solvent (component E)]
In one or more embodiments, the cleaning composition of the present disclosure may further contain an organic solvent (hereinafter also referred to as "component E"). Component E may be one type, or two or more types may be combined.
In one or more embodiments, Component E includes at least one solvent selected from glycol ethers and aromatic ketones.
From the viewpoints of improving resin mask removability, inhibiting copper corrosion, and reducing the effect on the substrate, examples of glycol ethers include compounds having a structure in which 1 to 3 moles of ethylene glycol are added to an alcohol having 1 to 8 carbon atoms. Specific examples of glycol ethers include at least one selected from diethylene glycol monobutyl ether (BDG), ethylene glycol monobenzyl ether, diethylene glycol monohexyl ether, ethylene glycol monophenyl ether, and diethylene glycol diethyl ether.
Examples of aromatic ketones include acetophenone and the like, from the viewpoints of improving resin mask removability, inhibiting copper corrosion, and reducing the influence on the substrate.

When the cleaning composition of the present disclosure contains component E, the content of component E during use of the cleaning composition of the present disclosure is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, from the viewpoint of improving resin mask removability. Also, from the viewpoints of inhibiting copper corrosion, reducing the burden on wastewater treatment, and reducing the impact on substrates, the content of component E is preferably 40% by mass or less, more preferably 20% by mass or less, and even more preferably 6% by mass or less. More specifically, the content of component E during use of the cleaning composition of the present disclosure is preferably 1% by mass or more and 40% by mass or less, more preferably 2% by mass or more and 20% by mass or less, and even more preferably 3% by mass or more and 6% by mass or less. When component E is a combination of two or more types, the content of component E refers to the total content of those components.

[Chelating agent (component F)]
In one or more embodiments, the cleaning composition of the present disclosure may further contain a chelating agent (hereinafter also referred to as "component F"). Component F may be one type, or two or more types may be combined.
Examples of Component F include compounds having two or more acid groups of at least one type selected from carboxy groups and phosphonic acid groups. From the viewpoints of improving resin mask removability and inhibiting copper corrosion, compounds having preferably four or fewer acid groups are preferred. Specific examples of Component F in one or more embodiments include aminotrimethylenephosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, etidronic acid (1-hydroxyethane-1,1-diphosphonic acid, HEDP), and the like. Among these, from the viewpoint of reducing the environmental load, compounds that do not contain nitrogen atoms, such as 2-phosphonobutane-1,2,4-tricarboxylic acid and etidronic acid (HEDP), are preferred.

The molecular weight of component F is preferably 1,000 or less, more preferably 500 or less, from the viewpoint of improving resin mask removability and inhibiting copper corrosion.

When the cleaning composition of the present disclosure contains component F, the content of component F during use of the cleaning composition of the present disclosure is preferably 0.5% by mass or more, more preferably 1% by mass or more, from the viewpoints of improving resin mask removability and inhibiting copper corrosion. From the same viewpoints, the content of component F during use of the cleaning composition of the present disclosure is preferably 5% by mass or less, more preferably 3% by mass or less. More specifically, the content of component F during use of the cleaning composition of the present disclosure is preferably 0.5% by mass or more and 5% by mass or less, more preferably 1% by mass or more and 3% by mass or less. When component F is a combination of two or more types, the content of component F refers to the total content of those components.

[Other ingredients]
The cleaning composition of the present disclosure may further contain other components as needed, in addition to the above-described Components A to F. Examples of other components include components that can be used in ordinary cleaning agents, such as organic solvents other than Component E, surfactants, chelating agents other than Component F, thickeners, dispersants, rust inhibitors, polymeric compounds, solubilizers, antioxidants, preservatives, antifoaming agents, and antibacterial agents.
The content of other ingredients in the cleaning composition of the present disclosure during use is preferably 0% by mass or more and 2% by mass or less, more preferably 0% by mass or more and 1.5% by mass or less, even more preferably 0% by mass or more and 1.3% by mass or less, and still more preferably 0% by mass or more and 1% by mass or less.

In one or more embodiments, the cleaning composition of the present disclosure may be free of fluorine compounds.

The total content of organic matter derived from Components A, B, C, and optional components (Components E, F, and other components) during use of the cleaning composition of the present disclosure is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 16% by mass or less, from the viewpoints of reducing the burden on wastewater treatment and reducing the impact on substrates. Also, from the viewpoint of improving resin mask removability, it is preferably 2% by mass or more, more preferably 3% by mass or more, even more preferably 4% by mass or more, and even more preferably 6% by mass or more. More specifically, the total content of organic matter derived from Components A, B, C, and optional components (Components E, F, and other components) during use of the cleaning composition of the present disclosure is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 25% by mass or less, even more preferably 4% by mass or more and 20% by mass or less, and even more preferably 6% by mass or more and 16% by mass or less.

[Method of producing the cleaning composition]
The cleaning composition of the present disclosure can be produced by blending an alkaline agent (component A), a source of ammonium ions (component B), thioglycolic acid (component C) or a salt thereof, water (component D), and, as necessary, the above-mentioned optional components, by a known method. For example, in one or more embodiments, the cleaning composition of the present disclosure can be a composition comprising a blend of an alkaline agent (component A), a source of ammonium ions (component B), thioglycolic acid (component C) or a salt thereof, and water (component D).
Thus, the present disclosure relates to a method for producing a detergent composition, comprising a step of blending at least an alkaline agent (component A), a source of ammonium ions (component B), thioglycolic acid (component C) or a salt thereof, and water (component D). In the present disclosure, "blending" includes mixing the alkaline agent (component A), the source of ammonium ions (component B), thioglycolic acid (component C) or a salt thereof, water, and, if necessary, the optional components described above, simultaneously or in any order. In the method for producing a detergent composition of the present disclosure, the preferred amount of each component may be the same as the preferred content of each component of the detergent composition of the present disclosure described above.

The cleaning composition of the present disclosure may be in a form ready for use in cleaning, or may be prepared as a concentrate by reducing the amount of water (component D) to a degree that does not impair storage stability due to separation or precipitation. From the perspective of transportation and storage, the concentrated cleaning composition is preferably diluted 3 times or more, and from the perspective of storage stability, it is preferably diluted 30 times or less. The concentrated cleaning composition can be diluted with water (component D) at the time of use so that each component (component A, component B, component C, component D, component E, component F, and other components) reaches the above-mentioned content (i.e., the content at the time of cleaning). Furthermore, the concentrated cleaning composition can also be used by adding each component separately at the time of use. In this disclosure, "at the time of use" or "at the time of cleaning" for a concentrated cleaning composition refers to the diluted state of the concentrated cleaning composition.

[Item to be cleaned]
In one or more embodiments, the cleaning composition of the present disclosure can be used to clean a substrate having a copper-containing metal layer and a resin mask on its surface. In one or more embodiments, the copper-containing metal layer is a copper plating layer. The copper plating layer can be formed, for example, by an electroless copper plating method.
In one or more other embodiments, the cleaning composition of the present disclosure can be used to clean an object having a resin mask attached thereto. In one or more embodiments, the object to be cleaned may be an object having a copper-containing metal site on its surface, such as an electronic component or a manufacturing intermediate thereof. Examples of the electronic component include at least one component selected from a printed circuit board, a wafer, and a metal plate such as a copper plate or an aluminum plate. The manufacturing intermediate is an intermediate product in the manufacturing process of an electronic component, including an intermediate product after a resin mask treatment. Specific examples of objects to be cleaned having a resin mask attached thereto include electronic components on which wiring, connection terminals, etc. are formed on the substrate surface by undergoing a process such as soldering using a resin mask or plating (copper plating, aluminum plating, nickel plating, etc.). Thus, in one aspect, the present disclosure relates to use of the cleaning composition of the present disclosure as a cleaning agent in the manufacture of electronic components.
In one or more embodiments, the cleaning composition of the present disclosure is excellent in removability of a resin mask present in fine gaps. From the viewpoint of ensuring that the cleaning composition exhibits excellent resin mask removability, the object to be cleaned is preferably a substrate having fine gaps in which a resin mask is present. An example of a substrate having fine gaps is a substrate having copper wiring (lines), the minimum value of which is preferably 1 μm or more, preferably 10 μm or less, and more preferably 6 μm or less.
In one or more embodiments, the cleaning composition of the present disclosure can suppress damage to substrate resins. To minimize damage to substrate resins caused by the cleaning composition, the object to be cleaned may be a substrate having a resin on its surface. For example, the substrate preferably has a solder resist resin.

In one or more embodiments, the cleaning composition of the present disclosure can be suitably used to clean an object having a resin mask or a resin mask that has been further plated and/or heated, from the viewpoint of cleaning effectiveness. The resin mask may be, for example, a negative resin mask or a positive resin mask. In the present disclosure, a negative resin mask is formed using a negative resist, and examples of such a mask include a negative resist layer that has been exposed to light and/or developed. In the present disclosure, a positive resin mask is formed using a positive resist, and examples of such a mask include a positive resist layer that has been exposed to light and/or developed.

[Cleaning method]
In one or more embodiments, the cleaning method of the present disclosure includes a step of peeling the resin mask from a substrate (object to be cleaned) having a copper-containing metal layer and a resin mask on its surface using the cleaning composition of the present disclosure (hereinafter also simply referred to as a "peeling step"). In one or more embodiments, the peeling step includes contacting the object to be cleaned with the cleaning composition of the present disclosure. According to the cleaning method of the present disclosure, the resin mask can be efficiently peeled and removed while suppressing copper corrosion and discoloration. According to one or more embodiments, the cleaning method of the present disclosure can efficiently peel and remove a resin mask present in a fine gap. According to one or more embodiments, the cleaning method of the present disclosure can suppress damage to the substrate resin. An example of the substrate resin is solder resist.

Methods for peeling resin masks from objects to be cleaned using the cleaning composition of the present disclosure, or methods for contacting objects to be cleaned with the cleaning composition of the present disclosure, include, for example, a method of contacting the objects by immersing them in a cleaning bath containing the cleaning composition, a method of contacting the objects by spraying the cleaning composition (shower method), and an ultrasonic cleaning method in which ultrasonic waves are applied during immersion. The cleaning composition of the present disclosure can be used for cleaning as is without dilution. Examples of objects to be cleaned include the objects described above.

In one or more embodiments, the cleaning method of the present disclosure may include a step of contacting the object to be cleaned with the cleaning composition, followed by rinsing with water and drying. In one or more embodiments, the cleaning method of the present disclosure may include a step of contacting the object to be cleaned with the cleaning composition, followed by rinsing with water.

In the cleaning method of the present disclosure, ultrasonic waves are preferably applied when the cleaning composition of the present disclosure comes into contact with the object to be cleaned, since this allows the cleaning power of the cleaning composition of the present disclosure to be more easily exerted. The ultrasonic waves are more preferably of a relatively high frequency. From the same viewpoint, the ultrasonic irradiation conditions are preferably, for example, 26 to 72 kHz and 80 to 1500 W, and more preferably 36 to 72 kHz and 80 to 1500 W.

In the cleaning method of the present disclosure, the temperature of the cleaning composition is preferably 40°C or higher, more preferably 50°C or higher, so that the cleaning power of the cleaning composition of the present disclosure can be easily exerted. From the viewpoint of reducing the impact on the substrate, the temperature is preferably 70°C or lower, more preferably 60°C or lower.

[Electronic component manufacturing method]
In one aspect, the present disclosure relates to a method for producing an electronic component (hereinafter also referred to as the "electronic component production method of the present disclosure"), which includes a step (cleaning step) of cleaning a substrate (object to be cleaned) having a copper-containing metal layer and a resin mask on its surface using the cleaning method of the present disclosure. Examples of the object to be cleaned include the objects described above. In one or more embodiments, the electronic component production method of the present disclosure can include a step of etching the copper-containing metal layer after the cleaning step.
In the method for manufacturing electronic components according to the present disclosure, cleaning is performed using the cleaning method according to the present disclosure, which can effectively remove the resin mask attached to the electronic components while suppressing corrosion and discoloration of copper, thereby enabling the manufacturing of highly reliable electronic components. Furthermore, since the cleaning method according to the present disclosure makes it easy to remove the resin mask attached to the electronic components, cleaning time can be shortened and the manufacturing efficiency of electronic components can be improved.

[kit]
In one aspect, the present disclosure relates to a kit for use in either the cleaning method of the present disclosure or the method for producing electronic components of the present disclosure (hereinafter also referred to as the "kit of the present disclosure"). In one or more embodiments, the kit of the present disclosure is a kit for producing the cleaning composition of the present disclosure. The kit of the present disclosure can provide a cleaning composition that has excellent resin mask removal properties and can inhibit copper corrosion and discoloration.

One embodiment of the kit of the present disclosure includes a kit (three-liquid cleaning composition) that contains a solution containing component A (first liquid), a solution containing component B (second liquid), and a solution containing component C (third liquid) in a mutually unmixed state, where at least one selected from the first, second, and third liquids further contains some or all of water (component D), and the first, second, and third liquids are mixed at the time of use. After the first, second, and third liquids are mixed, they may be diluted with water (component D) as needed. Each of the first, second, and third liquids may contain the optional components described above as needed.
Another embodiment of the kit of the present disclosure includes a kit (two-liquid cleaning composition) that includes a solution containing component A (first liquid) and a solution containing components B and C (second liquid) in a mutually unmixed state, where at least one of the first and second liquids further contains some or all of water (component D), and the first and second liquids are mixed at the time of use. After the first and second liquids are mixed, they may be diluted with water (component D) as needed. Each of the first and second liquids may contain the optional components described above as needed.

The present disclosure will be explained in detail below using examples, but the present disclosure is not limited to these examples in any way.

1. Preparation of Cleaning Compositions of Examples 1 to 9 and Comparative Examples 1 to 3 The cleaning compositions of Examples 1 to 9 and Comparative Examples 1 to 3 were prepared by blending the components shown in Tables 1 and 2 in the amounts (% by mass, active component) shown in Tables 1 and 2 and stirring to mix. Tables 1 and 2 show the content (mol/100 g, active component) of ammonium ion (component B), the content (mol/100 g, active component) of thioglycolic acid (component C), and the molar ratio (B/C) of ammonium ion/thioglycolic acid in each of the prepared cleaning compositions.

The following materials were used to prepare the detergent compositions of Examples 1 to 9 and Comparative Examples 1 to 3.
TMAH: tetramethylammonium hydroxide [manufactured by Showa Denko K.K., concentration 25%] (Component A)
MEA: Monoethanolamine [manufactured by Nippon Shokubai Co., Ltd.] (Component A)
Ammonia [Fujifilm Wako Pure Chemical Industries, Ltd., Grade 1, 25% aqueous solution] (source of component B)
Ammonium thioglycolate [Tokyo Chemical Industry Co., Ltd., 60% aqueous solution] (source of components B and C)
Water [pure water of 1 μS/cm or less produced using the Organo Corporation G-10DSTSET water purification system] (Component D)
BDG: Butyl diglycol [Nihon Nyukazai Co., Ltd., diethylene glycol monobutyl ether] (Component E)
HEDP: Etidronic acid [Italmatch Japan Co., Ltd., Dequest 2010, concentration 60%] (ingredient F)
Ammonium formate [Fujifilm Wako Pure Chemical Industries, Ltd.]
Dimethyl sulfoxide [Fujifilm Wako Pure Chemical Industries, Ltd.]

2. Evaluation of Cleaning Compositions (Examples 1 to 9 and Comparative Examples 1 and 2)
The prepared cleaning compositions of Examples 1 to 9 and Comparative Examples 1 and 2 were evaluated as follows.

[Preparation of test piece 1]
A photosensitive film for forming a PKG substrate circuit was laminated on the surface of the substrate after electroless plating under the following conditions, and then exposed to light to harden (exposure step), thereby obtaining a substrate (test piece 1, 30 mm × 50 mm) having a resin mask (hardened resist layer).
(1) Lamination: Using a clean roller (RY-505Z, manufactured by Rayon Kogyo Co., Ltd.) and a vacuum applicator (VA7024/HP5, manufactured by Rohm & Haas Co.), the roller temperature was 50° C. and the roller pressure was 1.4 Bar.
(2) Exposure: Exposure is performed using a direct imaging device for printed circuit boards (Mercurex LI-9500, manufactured by SCREEN Graphic and Precision Solutions Co., Ltd.) at an exposure dose of 15 mJ/cm ² .

[Cleaning test]
100 g of each of the cleaning compositions of Examples 1 to 9 and Comparative Examples 1 and 2 was added to a tall 200 mL glass beaker and heated to 50°C. Test Piece 1 was immersed in the mixture for 10 minutes while stirring at 600 rpm using a rotor (fluororesin (PTFE), φ8 mm x 25 mm). The mixture was then immersed in a rinsing tank containing 100 g of water in a 100 mL glass beaker, rinsed, and then dried with nitrogen blow.

[Removal time of resin mask (evaluation of peelability (removability)]
In the above cleaning test, the time (minutes) until the resin mask is completely removed is measured by visual observation.

[Evaluation of Cu etching rate (evaluation of copper corrosion (corrosivity)]
2.5 L of each cleaning composition was prepared and heated to 50°C. The composition was circulated in a box-type spray washer equipped with a full-cone nozzle (J020, manufactured by Ikeuchi Corporation) and sprayed for 4 minutes (pressure: 0.05 MPa, spray distance: 80 mm) onto test piece 2 (a substrate having a copper-plated layer on its surface) whose surface was copper-plated (area: 25 ^cm2 per side, 50 ^cm2 total). After diluting the cleaning composition, the amount of copper eluted was measured using ICP analysis (Agilent 5110 ICP-OES, manufactured by Agilent Technologies). The Cu etching rate (μm/min) was evaluated from the eluted amount using the following formula, assuming a copper density of 8.94 g/ ^cm3 . A lower Cu etching rate indicates a more excellent copper corrosion inhibition effect.
Cu etching rate (μm/min) = amount of copper dissolved (weight) ÷ copper density ÷ plating area ÷ processing time

[Appearance of copper on the substrate (evaluation of copper discoloration)]
In the evaluation of the etching rate, the presence or absence of discoloration of the copper portion is visually observed.

[Evaluation of damage to substrate resin]
The above cleaning test was carried out on a board (test piece 3) having a solder resist resin, and it was visually confirmed whether there was any change in color or the like in the resin part of the board before and after, and evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: No change was observed before and after the cleaning test.
B: A change was observed before and after the cleaning test.

As shown in Table 1, the cleaning compositions of Examples 1 to 9 were found to be more effective in inhibiting copper corrosion and discoloration and to have excellent resin mask removability than Comparative Example 1, in which the molar ratio B/C was outside the predetermined range, and Comparative Example 2, in which no component C was included.
Furthermore, when thioglycerol was used in place of ammonium thioglycolate in the cleaning composition of Example 3, the resin mask removal performance and copper discoloration suppression effect were inferior to those of Example 3 (data not shown).

3. Evaluation of Cleaning Compositions (Example 8 and Comparative Example 3)
The prepared cleaning compositions of Example 8 and Comparative Example 3 were used to carry out the following evaluations.

[Preparation of test piece 4 having thick film DF]
A photosensitive thick film (thickness: 140 μm) for forming a PKG substrate circuit was laminated on the surface of the substrate after electroless plating under the conditions described below, and then exposed to light to cure (exposure step), thereby obtaining a substrate (test piece 4, 30 mm × 50 mm) having a resin mask (cured resist layer).
(1) Lamination: Using a clean roller (RY-505Z, manufactured by Rayon Kogyo Co., Ltd.) and a vacuum applicator (VA7024/HP5, manufactured by Rohm & Haas Co.), the roller temperature was 50° C. and the roller pressure was 1.4 Bar.
(2) Exposure: Exposure is performed using a direct imaging device for printed circuit boards (Mercurex LI-9500, manufactured by SCREEN Graphic and Precision Solutions Co., Ltd.) at an exposure dose of 15 mJ/cm ² .

[Preparation of test piece 5 having fine line circuit pattern]
A photosensitive film for forming a PKG substrate circuit was laminated on the surface of the substrate after electroless plating under the conditions described below, exposed to light and cured (exposure step), and then electrolytic plating was carried out to obtain a resin mask (cured resist layer) with a line/space of 5 μm/5 μm and a substrate (test piece 5, 30 mm × 50 mm) having a fine-line circuit pattern.
(1) Lamination: Using a clean roller (RY-505Z, manufactured by Rayon Kogyo Co., Ltd.) and a vacuum applicator (VA7024/HP5, manufactured by Rohm & Haas Co.), the roller temperature was 50° C. and the roller pressure was 1.4 Bar.
(2) Exposure: Exposure is performed using a direct imaging device for printed circuit boards (Mercurex LI-9500, manufactured by SCREEN Graphic and Precision Solutions Co., Ltd.) at an exposure dose of 15 mJ/cm ² .

[Cleaning test]
100 g of each of the cleaning compositions of Example 8 and Comparative Example 3 was added to a 200 mL tall glass beaker and heated to 50°C. Test Piece 4 or 5 was immersed in the mixture for 10 minutes while stirring at 600 rpm using a rotor (fluororesin (PTFE), φ8 mm × 25 mm). Then, the mixture was immersed in a rinsing tank containing 100 g of water in a 100 mL glass beaker, rinsed, and then dried with nitrogen blow.

[Resin mask peeling time (evaluation of removability)]
In the above-described cleaning test of the test piece 4, the time (minutes) until the resin mask is completely removed is measured by visual observation.

[Removability of fine line circuit patterns (evaluation of removability)]
Using an optical microscope "Digital Microscope VHX-2000" (manufactured by Keyence Corporation), the presence or absence of the resin mask remaining in the fine line circuit pattern of test piece 5 after the cleaning test was visually confirmed at 1000x magnification.

As shown in Table 2, the cleaning composition of Example 8 was found to have superior resin mask removal properties compared to Comparison Example 3, which does not contain component C.

This disclosure provides a cleaning method that is excellent at removing resin masks and can suppress copper corrosion and discoloration. The cleaning method of this disclosure can shorten the cleaning process for electronic components with attached resin masks and improve the performance and reliability of the manufactured electronic components, thereby improving the productivity of semiconductor devices.

Claims (11)

The method includes a step of stripping a resin mask from a substrate having a copper-containing metal layer and a resin mask on its surface, using a cleaning composition containing tetraalkylammonium hydroxide , ammonium ions (NH ₄ ⁺ , component B), thioglycolic acid (component C), and water (component D) , wherein the molar ratio of component B to component C (B/C) is 1.5 or more;
In the detergent composition,
The content of tetraalkylammonium hydroxide is 0.5% by mass or more and 8% by mass or less,
The content of component B is 0.02 mol/100 g or more and 0.08 mol/100 g or less,
The content of component C is 0.4% by mass or more and 4% by mass or less.
How to clean a substrate. The cleaning method according to claim 1, wherein the copper-containing metal layer is a copper-plated layer. The cleaning method described in claim 1 or 2, wherein the resin mask is a hardened resist layer. The cleaning method according to any one of claims 1 to 3, wherein the content of component D in the cleaning composition when in use is 60 mass% or more. 5. The cleaning method according to claim 1 , wherein the substrate has copper wiring as the copper-containing metal layer , and the minimum spacing between the wiring is 1 μm or more and 10 μm or less. 6. The cleaning method according to claim 1, wherein the substrate is a substrate having a solder resist resin as a resin mask . A method for producing an electronic component, comprising the step of cleaning a substrate having a copper-containing metal layer and a resin mask on its surface, using the cleaning method according to any one of claims 1 to 6 . It contains tetraalkylammonium hydroxide , ammonium ion (NH ₄ ⁺ , component B), thioglycolic acid (component C), and water (component D) ,
the molar ratio of component B to component C (B/C) is 1.5 or more;
The content of tetraalkylammonium hydroxide is 0.5% by mass or more and 8% by mass or less,
The content of component B is 0.02 mol/100 g or more and 0.08 mol/100 g or less,
The content of component C is 0.4% by mass or more and 4% by mass or less .
A cleaning composition for removing resin masks. The cleaning composition according to claim 8 , wherein the total amount of the tetraalkylammonium hydroxide , component B, component C, and component D is 90 mass% or more. The cleaning composition according to claim 8 or 9 , wherein the content of component D is 60 mass% or more. Use of a cleaning composition containing tetraalkylammonium hydroxide , ammonium ions ( _NH4 ⁺ , component B), thioglycolic acid (component C), and water (component D) , in which the molar ratio of component B to component C (B/C) is 1.5 or more, the content of tetraalkylammonium hydroxide is 0.5% by mass or more and 8% by mass or less, the content of component B is 0.02 mol/100g or more and 0.08 mol/100g or less, and the content of component C is 0.4% by mass or more and 4% by mass or less , for cleaning a substrate having a copper-containing metal layer and a resin mask on its surface.