JP7644658B2 - Chemicals used in etching processes - Google Patents

Description

The present invention relates to a chemical solution used in the etching process of a workpiece in which a substrate, a copper thin film, and a copper-plated object are stacked in that order in the thickness direction of the substrate, and a method for manufacturing a substrate including a copper-plated object using the chemical solution.

In response to the trend toward more sophisticated and smaller semiconductor devices, flip-chip mounting has become widely used as a method for mounting and bonding semiconductor devices onto a substrate. In flip-chip mounting, numerous electrodes (bumps) are formed on a seed layer, mainly made of copper, on a substrate, and the semiconductor device is connected to the substrate via these electrodes.

A method has been proposed for manufacturing a wiring board with bumps that can be used for flip-chip mounting, in which a resist film is provided as a mold for forming electrodes on a seed layer formed on a substrate by electroless plating, and then post bumps made of copper are formed in the mold by electrolytic plating of the substrate, followed by removing the resist film and removing the seed layer exposed on the substrate surface by etching (see Patent Document 1).

JP 2018-157051 A

However, Patent Document 1 does not fully consider the removal by etching of the thin copper film serving as a seed layer after the plating mold has been removed. In the method described in Patent Document 1, when the seed layer is etched by a conventionally known method, not only the thin copper film serving as the seed layer but also a large amount of the copper-plated object, such as the copper terminal formed by plating, is etched.

The present invention has been made in consideration of the above situation, and aims to provide a chemical solution for etching that can effectively etch the thin copper film serving as a seed layer while preventing excessive etching of the copper-plated object, and a manufacturing method for a substrate having a copper-plated object, which includes performing etching using the chemical solution.

The inventors discovered that the above problems could be solved by adding an oxidizing substance (A) and water (W) to the chemical solution used in the etching process of the workpiece, which is a substrate, a copper thin film formed by a method other than plating, and a copper-plated object stacked in that order in the thickness direction of the substrate, using a combination of an oxoacid (A1a) and a peroxide (A1b) or a peracid (A2) as the oxidizing substance (A), and having the oxidizing substance (A) contain at least one of acetic acid as the oxoacid (A1a) and peracetic acid as the peracid (A2), and thus completed the present invention.

A first aspect of the present invention is a chemical solution used in an etching process of a processing object in which a substrate, a copper thin film, and a copper-plated object are stacked in this order in a thickness direction of the substrate, the chemical solution comprising:
The chemical solution contains an oxidizing substance (A) and water (W),
The oxidizing substance (A) comprises a combination of an oxoacid (A1a) and a peroxide (A1b), or a peracid (A2);
The oxidizing substance (A) contains at least one of acetic acid as the oxoacid (A1a) and peracetic acid as the peracid (A2);
a thin copper film covering at least a portion of a major surface of the substrate;
The copper thin film is a film formed by a method other than plating,
This is a chemical solution that produces a copper-plated object, which is an object formed by plating using a thin copper film as a seed layer.

A second aspect of the present invention is
forming a copper thin film on a substrate;
forming a plating mold on the copper thin film;
A step of plating copper on a substrate having a mold to form a copper-plated object in the mold;
After the copper-plated object is formed, the mold is peeled off;
and after peeling off the mold, etching the copper thin film using the chemical solution according to the first aspect.

The present invention provides a chemical solution for etching that can effectively etch a thin copper film serving as a seed layer while preventing excessive etching of a copper-plated object, and a method for manufacturing a substrate having a copper-plated object, which includes performing etching using the chemical solution.

The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following embodiments and can be modified as appropriate within the scope of the present invention.

<Chemical Solution>
The chemical solution is used for etching a processing target object in which a substrate, a copper thin film, and a copper-plated object are stacked in this order in the thickness direction of the substrate.
The copper thin film covers at least a part of the main surface of the substrate. The copper thin film is a film formed by a method other than plating. The copper-plated object is a shaped object formed by plating using the copper thin film as a seed layer.

By etching the above-mentioned workpiece with the chemical solution described below, only a small amount of the copper-plated object is etched, while a large amount of the copper thin film formed by a method other than plating can be etched as desired.

The chemical solution contains an oxidizing substance (A) and water (W).
The oxidizing substance (A) includes a combination of an oxoacid (A1a) and a peroxide (A1b), or a peracid (A2). The oxidizing substance (A) also includes at least one of acetic acid as the oxoacid (A1a) and peracetic acid as the peracid (A2).
The chemical solution may also contain optional components such as an anticorrosive agent (B) and a surfactant (C).

The chemical solution may be a one-liquid composition containing an oxidizing substance (A), water (W), and optional components as necessary. The chemical solution may also be a multi-liquid composition consisting of two or more liquids with different compositions.

Examples of the case where the drug solution is a multi-liquid composition include:
1) A chemical solution consisting of a first liquid containing an oxidizing substance (A) and water (W) and a second liquid containing an anticorrosive agent (B);
2) A chemical solution consisting of a first liquid containing an oxidizing substance (A) and water (W) and a second liquid containing a surfactant (C);
3) A chemical solution consisting of a first liquid containing an oxidizing substance (A) and water (W) and a second liquid containing an anticorrosive agent (B) and a surfactant (C);
4) A chemical solution consisting of a first liquid containing an oxoacid (A1a) and water (W) and a second liquid containing a peroxide (A1b);
5) A chemical solution consisting of a first liquid containing acetic acid as an oxoacid (A1a) and water (W) and a second liquid containing a peroxide (A1b);
6) A chemical solution comprising a first liquid containing acetic acid as an oxoacid (A1a) and water (W), a second liquid containing an oxoacid other than acetic acid as the oxoacid (A1a) and water (W), and a third liquid containing a peroxide (A1b);
7) A chemical solution comprising a first liquid containing an oxoacid (A1a) and water (W), a second liquid containing a peroxide (A1b), and a third liquid containing an anticorrosive agent (B);
8) A chemical solution comprising a first liquid containing an oxoacid (A1a) and water (W), a second liquid containing a peroxide (A1b), and a third liquid containing a surfactant (C);
9) A chemical solution comprising a first liquid containing an oxoacid (A1a) and water (W), a second liquid containing a peroxide (A1b), and a third liquid containing an anticorrosive agent (B) and a surfactant (C);
10) A chemical solution comprising a first liquid containing acetic acid as an oxoacid (A1a) and water (W), a second liquid containing a peroxide (A1b), and a third liquid containing a corrosion inhibitor (B);
11) A chemical solution comprising a first liquid containing acetic acid as an oxoacid (A1a) and water (W), a second liquid containing a peroxide (A1b), and a third liquid containing a surfactant (C);
12) A chemical solution comprising a first liquid containing acetic acid as an oxoacid (A1a) and water (W), a second liquid containing a peroxide (A1b), and a third liquid containing a corrosion inhibitor (B) and a surfactant (C);
13) A chemical solution comprising a first liquid containing acetic acid as an oxoacid (A1a) and water (W), a second liquid containing an oxoacid other than acetic acid as the oxoacid (A1a) and water (W), a third liquid containing a peroxide (A1b), and a fourth liquid containing a corrosion inhibitor (B);
14) A chemical solution comprising a first liquid containing acetic acid as an oxoacid (A1a) and water (W), a second liquid containing an oxoacid other than acetic acid as the oxoacid (A1a) and water (W), a third liquid containing a peroxide (A1b), and a fourth liquid containing a surfactant (C);
15) A chemical solution comprising a first liquid containing acetic acid as an oxoacid (A1a) and water (W), a second liquid containing an oxoacid other than acetic acid as the oxoacid (A1a) and water (W), a third liquid containing a peroxide (A1b), and a fourth liquid containing a corrosion inhibitor (B) and a surfactant (C);
16) A chemical solution consisting of a first liquid containing peracid (A1b) and water (W) and a second liquid containing an anticorrosive agent (B);
17) A chemical solution consisting of a first liquid containing a peracid (A1a) and water (W) and a second liquid containing a surfactant (C);
18) A chemical solution consisting of a first liquid containing a peracid (A1a) and water (W) and a second liquid containing a corrosion inhibitor (B) and a surfactant (C);
19) A chemical solution consisting of a first liquid containing peracetic acid as a peracid (A1b) and water (W) and a second liquid containing an anticorrosive (B);
20) A chemical solution consisting of a first liquid containing peracetic acid as a peracid (A1b) and water (W) and a second liquid containing a surfactant (C);
21) A chemical solution consisting of a first liquid containing peracetic acid as a peracid (A1b) and water (W) and a second liquid containing a corrosion inhibitor (B) and a surfactant (C);

22) A chemical solution consisting of a first liquid containing peracetic acid as the peracid (A1b) and water (W), a second liquid containing a peracid other than peracetic acid as the peracid (A1b) and water (W), and a third liquid containing an anticorrosive agent (B);
23) A chemical solution comprising a first liquid containing peracetic acid as the peracid (A1b) and water (W), a second liquid containing a peracid other than peracetic acid as the peracid (A1b) and water (W), and a third liquid containing a surfactant (C); and
24) A chemical solution comprising a first liquid containing peracetic acid as the peracid (A1b) and water (W), a second liquid containing a peracid other than peracetic acid as the peracid (A1b) and water (W), and a third liquid containing an anticorrosive agent (B) and a surfactant (C);
Examples include:
The liquid drug, which is a multi-liquid composition, is not limited to the above examples 1) to 24).

In the example of a chemical solution that is a multi-liquid composition, when the anticorrosive agent (B) and the surfactant (C) are in liquid form, the liquid containing the anticorrosive agent (B) and/or the surfactant (C) may not contain a solvent. Water (W) can be used as the solvent. Various organic solvents can also be used as the solvent as long as the desired effect is not impaired.

A chemical solution consisting of a first liquid containing acetic acid as the oxoacid (A1a) and water (W) and a second liquid containing a peroxide (A1b) is preferred as a chemical solution that is a multi-liquid composition, because it is effective in etching only a small amount of a copper-plated object while etching a desired amount of a thin copper film formed by a method other than plating, and because the chemical solution is easy to prepare and use.
The first liquid containing acetic acid as the oxoacid (A1a) and water (W) may contain an oxoacid other than acetic acid.
The first liquid containing acetic acid as the oxoacid (A1a) and water (W), and the second liquid containing the peroxide (A1b) may each contain a corrosion inhibitor (B) and/or a surfactant (C).

When the chemical solution is a multi-liquid composition, the above-mentioned workpiece is etched using a mixed solution obtained by mixing two or more liquids that make up the multi-liquid composition.

The following describes the object to be etched with the above-mentioned chemical solution and the essential and optional components contained in the chemical solution.

<Object to be treated>
As described above, the target object for etching with the above-mentioned chemical solution is a processing target in which a substrate, a copper thin film, and a copper-plated object are stacked in this order in the thickness direction of the substrate.
The copper thin film covers at least a part of the main surface of the substrate. The copper thin film is a film formed by a method other than plating. The copper-plated object is a shaped object formed by plating using the thin film as a seed layer.

As the substrate constituting the workpiece, a substrate applied to a mounting method such as flip-chip mounting can be used without any particular limitation. As the material of the surface of the substrate covered with the copper thin film described below, for example, a metal used as the material of the under-bump metal layer that has been used in combination with the copper thin film in the past can be used. Examples of metals used as the material of the under-bump metal layer include titanium, titanium-tungsten alloy, and titanium-copper alloy. As the material of the other layer in contact with the layer corresponding to the under-bump metal layer in the substrate, a semiconductor such as silicon can be used. In other words, a semiconductor substrate having a layer corresponding to the above-mentioned under-bump metal layer on at least one main surface can be preferably used as the substrate constituting the workpiece.

The copper thin film is formed so as to cover at least a part of the main surface of the substrate by a method other than plating. Examples of the method for forming the copper thin film include a physical vapor deposition method (PVD method), an ion plating method, and a sputtering method. Among these methods, the physical vapor deposition method is preferred because it is easy to form a copper thin film that is easily etched by a chemical solution.
The thickness of the copper thin film is not particularly limited. Typically, the thickness of the copper thin film is preferably 50 nm or more and 300 nm or less, more preferably 70 nm or more and 250 nm or less, and further preferably 100 nm or more and 200 nm or less.

A copper-plated object is an object formed by plating using a thin copper film as a seed layer. There is no particular limitation on the method for producing the copper-plated object. Typically, a mold having a void corresponding to the shape of the copper-plated object is formed on the thin copper film as a seed layer at the position where the copper-plated object is to be formed, and then a substrate having the mold is plated with copper by a known method to form the copper-plated object. Note that the thin copper film as a seed layer is exposed in the void.
The method for forming the template is not particularly limited. Typically, the template can be formed by a general photolithography method using a photosensitive composition.
The photosensitive composition is not particularly limited as long as it can form a film that is durable against a plating solution. The photosensitive composition may be a negative composition that is hardened by exposure to light and becomes insoluble in a developer, or a positive composition that is soluble in a developer by exposure to light.
After copper plating as described above, the template is peeled off from the substrate by a well-known method that depends on the type of composition used to form the template.

The copper-plated object is typically a bump (electrode) such as a metal post, or a copper wiring or copper rewiring. There are no particular limitations on the shape of the copper-plated object, but the height of the copper-plated object in the thickness direction of the substrate is preferably 2 μm or more and 6 μm or less, and more preferably 2.5 μm or more and 4 μm or less, in the case of a rewiring layer, and is preferably 10 μm or more and 300 μm or less, and more preferably 20 μm or more and 70 μm or less, in the case of a bump.

<Oxidizing substance (A)>
The oxidizing substance (A) includes a combination of an oxoacid (A1a) and a peroxide (A1b), or a peracid (A2).
The oxidizing substance (A) essentially contains at least one of acetic acid as the oxoacid (A1a) and peracetic acid as the peracid (A2).
By including the oxidizing substance (A) in the chemical solution, the copper plated object is only slightly etched, while a copper thin film formed by a method other than plating can be etched to a desired extent.

[Oxoacid (A1a)]
As described above, the oxo acid (A1a) essentially contains acetic acid. The content of acetic acid in the chemical solution is not particularly limited as long as the desired effect is not impaired. The content of acetic acid in the chemical solution is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.002% by mass or more and 2% by mass or less, and even more preferably 0.003% by mass or more and 1% by mass or less, based on the mass of the chemical solution.
In addition, the chemical liquid may be a multi-liquid type of two or more liquids, as described below. When the chemical liquid is a multi-liquid type, the content of acetic acid in the chemical liquid is the ratio of the mass of acetic acid to the total mass of the multiple liquids.

The oxoacid (A1a) may contain only acetic acid, or may contain acetic acid and an oxoacid other than acetic acid. In the specification of the present application, the oxoacid (A1a) is an oxoacid that does not fall under the category of peroxides having an -O-O- bond. Examples of oxoacids other than acetic acid include carboxylic acids other than acetic acid, halogen oxoacids, silicic acid, nitrous acid, nitric acid, phosphorous acid, phosphoric acid, sulfurous acid, sulfuric acid, and sulfonic acids.
The oxoacid (A1a) is a monobasic acid having one acidic group in the molecule, and is not a polybasic acid having two or more acidic groups in the molecule.
Specific examples of carboxylic acids other than acetic acid include formic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, benzoic acid, and lactic acid, etc. Specific examples of halogen oxoacids include hypochlorous acid, chlorous acid, chloric acid, hypobromous acid, bromous acid, and bromic acid, etc.
Of the above oxoacids that can be used together with acetic acid, phosphoric acid (H ₃ PO ₄ ) is preferred because it is capable of easily etching a thin copper film formed by a method other than plating.

The content of the oxoacid other than acetic acid in the chemical solution is not particularly limited as long as the desired effect is not impaired. The content of the oxoacid other than acetic acid in the chemical solution is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.2% by mass or more and 7% by mass or less, and even more preferably 0.5% by mass or more and 5% by mass or less, based on the mass of the chemical solution.
In addition, the chemical solution may be a multi-liquid type of two or more liquids, as described below. When the chemical solution is a multi-liquid type, the content of the oxoacid other than acetic acid in the chemical solution is the ratio of the mass of the oxoacid other than acetic acid to the total mass of the multiple liquids.

[Peroxide (A1b)]
The peroxide (A1b) is not particularly limited as long as it is a compound having an -O-O- bond. The peroxide may be a compound corresponding to the peracid (A1c) described below. In the specification of the present application, when the chemical solution contains a peracid together with the oxoacid (A1a), the chemical solution is deemed to contain the oxoacid (A1a) and the peracid as the peroxide (A1b).

Specific examples of the peroxide (A1b) include inorganic peroxides such as hydrogen peroxide, lithium peroxide, and potassium peroxide; organic peroxides such as tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, dimethydioxirane, acetone peroxide, methyl ethyl ketone peroxide, and hexamethylene triperoxide diamine; and peracids such as persulfuric acid, percarbonic acid, perphosphoric acid, hypoperchloric acid, hypoperbromic acid, hypoperiodic acid, and percarboxylic acid.
Examples of percarboxylic acids include performic acid, perbenzoic acid, and m-chloroperbenzoic acid.

Among the above peroxides (A1b), hydrogen peroxide is preferred because it is inexpensive and easy to handle, and because it is easy to etch thin copper films formed by methods other than plating using a chemical solution.

The content of peroxide (A1b) in the chemical solution is 5% by mass or less, and preferably 1% by mass or less, based on the total mass of the chemical solution.

[Peracid (A2)]
The chemical solution may contain a peracid (A2) as the oxidizing substance (A). As described above, in the specification of the present application, when the chemical solution contains a peracid together with an oxoacid (A1a), the chemical solution is defined as containing the oxoacid (A1a) and the peracid as the peroxide (A1b).

When the chemical solution contains a peracid (A2), the chemical solution contains peracetic acid as the peracid (A2). The content of peracetic acid in the chemical solution is not particularly limited as long as the desired effect is not impaired.
The content of peracetic acid in the chemical solution is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.002% by mass or more and 2% by mass or less, and even more preferably 0.003% by mass or more and 1% by mass or less, based on the mass of the chemical solution.
In addition, the chemical liquid may be a multi-liquid type of two or more liquids as described below. When the chemical liquid is a multi-liquid type, the content of peracetic acid in the chemical liquid is the ratio of the mass of peracetic acid to the total mass of the multiple liquids.

The chemical solution may contain a peracid other than peracetic acid as the peracid (A2) in addition to peracetic acid. As the peracid other than peracetic acid, the same compound as the peracid described for the peroxide (A1b) can be used.
Among peracids other than peracetic acid that can be used together with peracetic acid, perphosphoric acid is preferred because it is easy to etch a thin copper film formed by a method other than plating.

The content of the peracid other than peracetic acid in the chemical solution is not particularly limited as long as the desired effect is not impaired. The content of the peracid other than peracetic acid in the chemical solution is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.2% by mass or more and 7% by mass or less, and even more preferably 0.5% by mass or more and 5% by mass or less, based on the mass of the chemical solution.
In addition, the chemical solution may be a multi-liquid type of two or more liquids, as described below. When the chemical solution is a multi-liquid type, the content of peracid other than peracetic acid in the chemical solution is the ratio of the mass of peracid other than peracid to the total mass of multiple liquids.

[Corrosion inhibitor (B)]
The chemical solution may contain an anticorrosive agent (B). By containing the anticorrosive agent (B) in the chemical solution, the copper thin film can be etched while suppressing an increase in the surface roughness of the copper-plated object after etching. As the anticorrosive agent (B), a compound known to be used as an anticorrosive agent for copper can be used without any particular limitation.

Preferred examples of the corrosion inhibitor (B) include nitrogen-containing compounds selected from 1H-imidazoles, pyrazoles, thiazoles, triazoles, and guanidines. These may be used alone or in combination of two or more.

Examples of 1H-imidazoles include 1H-imidazole, 2-methyl-1H-imidazole, 2-ethyl-1H-imidazole, 2-isopropyl-1H-imidazole, 2-propyl-1H-imidazole, 2-butyl-1H-imidazole, 4-methyl-1H-imidazole, 2,4-dimethyl-1H-imidazole, 2-ethyl-4-methyl-1H-imidazole, 2-amino-1H-imidazole, and 1H-benzimidazole-2-thiol (2-mercaptobenzimidazole).
Examples of pyrazoles include 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole, 3-amino-5-hydroxypyrazole, and 3-amino-5-methylpyrazole.
Examples of the thiazoles include 2-aminothiazole, 4,5-dimethylthiazole, 2-amino-2-thiazoline, 2,4-dimethylthiazole, and 2-amino-4-methylthiazole.
Examples of triazoles include 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 1,2,4-triazolo[1,5-a]pyrimidine, 1,2,3-triazolo[4,5-b]pyridine, benzotriazole, and 5-methylbenzotriazole.
The guanidines include guanidine, 1,3-diphenylguanidine, 1-(orthotolyl) biguanide, and the like.

The content of the corrosion inhibitor (B) in the chemical solution is not particularly limited as long as the desired effect is not impaired. The preferred range of the content of the corrosion inhibitor (B) in the chemical solution is preferably 0.0001% by mass or more and 10% by mass or less, more preferably 0.001% by mass or more and 5% by mass or less, and even more preferably 0.01% by mass or more and 1% by mass or less, based on the mass of the chemical solution.

[Surfactant (C)]
The inclusion of the surfactant (C) in the chemical solution improves the wettability of the chemical solution to the material constituting the workpiece, such as a copper-plated object, and as a result, even when a thin copper film is located near the bottom of multiple copper-plated objects that are very close to each other, the chemical solution can easily penetrate into the gaps between the copper-plated objects, and the thin copper film can be efficiently etched.

The surfactant (C) is not particularly limited, and any conventionally known surfactant can be used. Any of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants can be used as the surfactant (C).

As the nonionic surfactant, for example, an alkylene oxide adduct of a diol having a carbon-carbon triple bond, or an alkylene oxide adduct of a monol having a carbon-carbon triple bond is preferable.
As the alkylene oxide adduct of a diol having a carbon-carbon triple bond, for example, a nonionic surfactant represented by the following formula (c-1) is preferred.
HO-(R ^c6 -O) _n1 -CR ^c3 R ^c4 -C≡C-CR ^c1 R ^c2 -(O-R ^c5 ) _n2 -OH...(c-1)
In formula (c-1), R ^c1 to R ^c4 are each independently a linear or branched alkyl group having from 1 to 6 carbon atoms. ^{R c5} and R ^c6 are each independently a linear or branched alkylene chain having from 2 to 4 carbon atoms. n1 and n2 are each independently an integer of from 0 to 30.

R ^c1 to R ^c4 are preferably a methyl group, an ethyl group, or an isopropyl group. ^{R c5} and R ^c6 are preferably an ethane-1,2-diyl group (ethylene group), a propane-1,3-diyl group, a propane-1,2-diyl group, or a butane-1,4-diyl group. n1 and n2 are preferably integers of 0 or more and 16 or less.

Specific examples of alkylene oxide adducts of diols having a carbon-carbon triple bond and alkylene oxide adducts of monools having a carbon-carbon triple bond include Olfin EXP4200 manufactured by Nissin Chemical Industry Co., Ltd., the "Surfynol 104 series" such as Surfynol 104E, Surfynol 104H, Surfynol 104A, Surfynol 104PA, and Surfynol 104PG-50 manufactured by Air Products Co., Ltd., and the "Surfynol 400 series" such as Surfynol 420, Surfynol 445, Surfynol 465, and Surfynol 485 manufactured by Air Products Co., Ltd. Among these, the "Surfynol 400 series" is preferred.

Examples of the anionic surfactant include an anionic surfactant represented by the following formula (c-2).
R ^c7 -SO ₃ H... (c-2)

In formula (c-2), R ^c7 is a linear or branched alkyl group having from 7 to 20 carbon atoms. The alkyl group may have a hydroxyl group and/or a carboxyl group, and may be interrupted by a phenylene group and/or an oxygen atom.
R ^c7 is preferably a linear or branched alkyl group having 8 to 11 carbon atoms.

Specific examples of the anionic surfactant represented by formula (c-2) include n-octanesulfonic acid, n-nonanesulfonic acid, n-decanesulfonic acid, and n-undecanesulfonic acid. Among these, n-octanesulfonic acid, n-nonanesulfonic acid, and n-decanesulfonic acid are preferred.

The content of the surfactant (C) in the chemical solution is not particularly limited as long as the desired effect is not impaired. The preferred range of the content of the surfactant (C) in the chemical solution is preferably 0.0001% by mass to 10% by mass, more preferably 0.001% by mass to 5% by mass, and even more preferably 0.01% by mass to 1% by mass, based on the mass of the chemical solution.

[Chelating Agent (D)]
The chemical solution may contain a chelating agent (D). The chelating agent (D) is a compound that does not fall under the above-mentioned oxoacid (A1a), which is a monobasic acid having one acidic group in the molecule. When the chemical solution contains the chelating agent (D), the peroxide (A1b) and peracid (A2) in the chemical solution are stabilized.
Examples of the chelating agent include hydroxyethylidene diphosphonic acid (HEDP), nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), glutamic acid diacetic acid (CMGA), aminotrimethylenephosphonic acid (ATMP), ethylenediaminetetramethylenephosphonic acid (EDTMP), phosphonobutanetricarboxylic acid (PBTC), citric acid, succinic acid, oxalic acid, phthalic acid, malic acid, tartaric acid, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraaminehexaacetic acid (TTHA), and glycol ether diaminetetraacetic acid (GEDTA).
These chelating agents may be used in the form of a salt such as an alkali metal salt or an ammonium salt.

The content of the chelating agent (D) in the chemical solution is not particularly limited as long as the desired effect is not impaired. The preferred range of the content of the chelating agent (D) in the chemical solution is preferably 0.001% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 5% by mass or less, and even more preferably 0.1% by mass or more and 2% by mass or less, based on the mass of the chemical solution.

[Water-soluble organic solvent (O)]
The chemical solution may contain a water-soluble organic solvent (O) to the extent that the desired effect is not impaired. By including the water-soluble organic solvent (O) in the chemical solution, it is possible to easily dissolve components that are difficult to dissolve in water (W) in the chemical solution.

Specific examples of water-soluble organic solvents (O) include sulfolane; hexamethylphosphoric triamide; sulfoxides such as dimethyl sulfoxide; sulfones such as dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone, ethyl isopropyl sulfone, 3-methyl sulfone, bis(2-hydroxyethyl) sulfone, and tetramethylene sulfone; amides such as N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide, N-methylacetamide, and N,N-diethylacetamide; lactams such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone, and N-hydroxyethyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, and 1,3-diethyl-2-imidazolidinone. imidazolidinones such as lysinone and 1,3-diisopropyl-2-imidazolidinone; alkanols such as methanol, ethanol, and isopropyl alcohol; polyhydric alcohols such as ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, glycerin, and diethylene glycol; lactones such as β-propiolactone, γ-butyrolactone, δ-pentyrolactone, γ-valerolactone, and γ-nonalactone; propylene carbonate; tetrahydrofuran; the above lactams, as well as nitrogen-containing heterocyclic compounds that are liquid at atmospheric pressure and 25°C and do not fall under the category of corrosion inhibitor (B), such as 1-methylimidazole, 1-(3-aminopropyl)imidazole, piperidine, and 2-oxazolidinone.

The content of the water-soluble organic solvent (O) in the drug solution is not particularly limited as long as the desired effect is not impaired. The content of the water-soluble organic solvent (O) in the drug solution is, for example, preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 10% by mass or less, based on the mass of the drug solution. It is preferable that the drug solution contains only water (W) as a solvent.

[Other ingredients]
The chemical solution may contain, in addition to the above components, an antifoaming agent, etc. The amounts of these components used are appropriately determined taking into consideration the amounts in which each component is normally used.

[Water (W)]
The water (W) is not particularly limited as long as it does not impair the desired effect, and water of various qualities can be used. For example, ion-exchanged water, distilled water, ion-exchanged distilled water, etc. are preferable, and ion-exchanged distilled water is more preferable.
The liquid medicine is prepared by dissolving the essential or optional components of the liquid medicine described above in desired amounts in water (W).

By using the chemical solution described above, it is possible to effectively etch the thin copper film serving as a seed layer while preventing excessive etching of the copper-plated object.
More specifically, for the chemical solutions described above, the ratio ER2/ER1 of the etching rate ER1 for the copper-plated object to the etching rate ER2 for the thin copper film is preferably 2.5 or more, more preferably 2.9 or more, and particularly preferably 3.0 or more.
The greater the content of acetic acid or peracetic acid in the chemical solution, the greater the value of the ratio ER2/ER1.

The contact angle of the chemical solution on the surface of the copper-plated object is preferably less than 100°, more preferably 95° or less, even more preferably 90° or less, and particularly preferably 85° or less, where the contact angle is a value measured before the plated object comes into contact with the chemical solution.
By ensuring that the contact angle of the chemical solution on the surface of the copper-plated object satisfies the above condition, even if the thin copper film is located near the bottom of multiple adjacent copper-plated objects that are located in close proximity, the chemical solution can penetrate well into the gaps between the copper-plated objects, and the thin copper film can be etched well.

Examples of the method for reducing the contact angle of the above-mentioned chemical solution include a method in which a surfactant (C) is contained in the chemical solution, and a method in which a water-soluble organic solvent is added to the chemical solution.
Here, the contact angle of the chemical solution is a static contact angle, which is measured, for example, by using a Dropmaster 700 (manufactured by Kyowa Interface Science Co., Ltd.) to drop a 2.0 μL droplet of the chemical solution onto the surface of the copper-plated object after contact with the chemical solution, and then as the contact angle 5 seconds after the drop.

When the copper-plated object is brought into contact with the chemical solution for 200 seconds, the arithmetic mean height Ra of the surface of the copper-plated object measured by an atomic force microscope (AFM) is preferably 35 nm or less, more preferably 30 nm or less, and even more preferably 20 nm or less.
When the copper-plated object is brought into contact with the chemical solution for 200 seconds, the root mean square height Rq of the surface of the copper-plated object measured by an atomic force microscope (AFM) is preferably 50 nm or less, more preferably 40 nm or less, and even more preferably 30 nm or less.
When the copper-plated object is brought into contact with the chemical solution for 200 seconds, the Z-range on the surface of the copper-plated object measured by an atomic force microscope (AFM) is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. The Z-range is the difference between the maximum height value and the minimum height value regarding the height information regarding the unevenness of the measurement target surface obtained by the atomic force microscope (AFM) before the plane fitting process.

<Method for manufacturing a substrate having a copper-plated object>
A method for manufacturing a substrate having a copper-plated object includes the steps of:
forming a copper thin film on a substrate;
forming a plating mold on the copper thin film;
A step of plating copper on a substrate having a mold to form a copper-plated object in the mold;
After the copper-plated object is formed, the mold is peeled off;
After the mold is peeled off, the copper thin film is etched using the above-mentioned chemical solution.

The chemical solutions for the process of forming a thin copper film on a substrate, the process of forming a plating mold on the thin copper film, the process of copper plating the substrate with the mold to form a copper-plated object in the mold, and the process of peeling off the mold after the copper-plated object has been formed are as described above.

In the step of etching the copper thin film using the above-mentioned chemical solution after the mold is peeled off, the etching method is not particularly limited as long as it is a method that can bring the copper thin film into contact with the above-mentioned chemical solution.
Examples of methods for etching a substrate, which is made up of a substrate, a thin copper film, and a copper-plated object stacked in that order in the thickness direction of the substrate, by contacting the above-mentioned chemical solution with the substrate include a spray method, an immersion method, and a puddle method.
In the spray etching, for example, the workpiece is conveyed or rotated in a predetermined direction, and the etching solution is sprayed into the space between the workpiece and the workpiece to bring the etching solution into contact with the workpiece. If necessary, the etching solution may be sprayed onto the workpiece while rotating it using a spin coater.
In the immersion etching method, the object to be treated is immersed in a liquid bath containing a chemical solution, and the object to be treated is brought into contact with the chemical solution within the liquid bath.
In etching using the puddle method, a chemical solution is puddled on the surface of the object to be etched, and the object is brought into contact with the chemical solution.
These etching methods may be appropriately selected depending on the structure, material, etc. of the object to be processed.

The time for which the chemical solution is in contact with the workpiece is appropriately determined taking into consideration the thickness of the copper thin film, etc. The temperature of the chemical solution during etching is not particularly limited as long as the copper-plated object is not excessively etched or the substrate is not damaged. The temperature of the chemical solution is typically preferably 10°C or higher and 40°C or lower, and more preferably 15°C or higher and 30°C or lower.

The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to the following examples.

[Examples 1 to 9 and Comparative Example 1]
In the examples and comparative examples, a workpiece was used that included a silicon substrate having a thin titanium film on one of its main surfaces, a thin copper film having a thickness of 800 nm formed by physical vapor deposition covering the exposed surface of the silicon substrate where the thin titanium film was located, and a copper-plated object having a thickness of 4 μm covering part of the thin copper film.

The components shown in Table 1 in their types and amounts were mixed uniformly to obtain the chemical solutions of Examples 1 to 9 and Comparative Example 1.
In the examples, 1,2,4-triazole was used as the corrosion inhibitor (B). In the examples, the following C1 to C3 were used as the surfactant (C). In the examples and comparative examples, hydroxyethylidene diphosphonic acid (HEDP) was used as the chelating agent (D).
C1: Olfin EXP4200 (manufactured by Nissin Chemical Industry Co., Ltd.)
C2: Surfynol 104 (manufactured by Air Products)
C3: Surfynol 465 (manufactured by Air Products)
The hydrogen peroxide was added to the chemical solution as a 31% by mass aqueous hydrogen peroxide solution containing 0.56 parts by mass of hydrogen peroxide and 1.24 parts by mass of water. In other words, of the amount of water (W) shown in Table 1, 1.24 parts by mass is derived from the aqueous hydrogen peroxide solution.

Using the obtained chemical solution, the etching rate was measured according to the following methods, the contact angle of the chemical solution on the surface of the thin copper film and the surface of the copper-plated object was measured, and the surface roughness of the copper-plated object surface after contact with the chemical solution was measured. The results of these measurements are shown in Table 2.

<Measurement of Etching Rate>
The above-mentioned workpieces were immersed in the chemical solutions of each of the Examples and Comparative Examples at approximately 20° C. for 200 seconds, and then the thickness of the thin copper film and the thickness of the copper-plated object were measured using a sheet resistance meter, and the etching rate (Å/sec) was calculated.

<Contact angle measurement with chemical solution>
Using the workpiece before contact with the chemical solution as a sample, the contact angle of the chemical solution on the surface of the thin copper film and on the surface of the copper-plated object was measured by the method described above.

<Measurement of surface roughness of copper-plated object after contact with chemical solution>
The above-mentioned objects to be treated were immersed in the chemical solutions of the Examples and Comparative Examples at about 20° C. for 200 seconds, and then the surfaces of the objects to be treated were rinsed with ion-exchanged distilled water for 30 seconds. After rinsing, nitrogen gas was sprayed onto the objects to be treated for 20 seconds to dry them.
The dried treated body was used as a measurement sample, and the arithmetic mean height Ra, root mean square height Rq, and Z range of the surface of the copper-plated object were measured using an atomic force microscope (AFM).

According to Tables 1 and 2, when a workpiece having a silicon substrate with a thin titanium film, a thin copper film formed by physical vapor deposition, and a copper-plated object stacked in that order is etched with an example chemical solution containing an oxidizing substance (A) containing an oxoacid (A1a) and a peroxide (A1b), as well as water (W), and containing acetic acid as the oxoacid (A1a), it is possible to effectively etch the thin copper film while preventing excessive etching of the copper-plated object.
On the other hand, according to Tables 1 and 2, when a chemical solution containing an oxidizing substance (A) containing an oxoacid (A1a) and a peroxide (A1b), and water (W) but not acetic acid is used, a large amount of the copper-plated object is etched.

Claims (8)

A chemical solution used in an etching process of a processing target object in which a substrate, a copper thin film, and a copper-plated object are stacked in this order in the thickness direction of the substrate,
The chemical solution contains an oxidizing substance (A) and water (W),
the oxidizing substance (A) comprises a combination of an oxoacid (A1a) and a peroxide (A1b), or a peracid (A2);
The oxidizing substance (A) contains at least one of acetic acid as the oxoacid (A1a) and peracetic acid as the peracid (A2),
the copper thin film covers at least a portion of a main surface of the substrate;
The copper thin film is a film formed by a method other than plating,
the copper-plated object is a object formed by plating using the copper thin film as a seed layer,
The chemical solution has a ratio, ER2/ER1, of an etching rate ER1 for the copper plated object to an etching rate ER2 for the copper thin film, of 2.5 or more . A chemical solution used in an etching process of a processing target object in which a substrate, a copper thin film, and a copper-plated object are stacked in this order in the thickness direction of the substrate,
The chemical solution contains an oxidizing substance (A) and water (W),
the oxidizing substance (A) comprises a combination of an oxoacid (A1a) and a peroxide (A1b), or a peracid (A2);
The oxidizing substance (A) contains at least one of acetic acid as the oxoacid (A1a) and peracetic acid as the peracid (A2),
the copper thin film covers at least a portion of a main surface of the substrate;
The copper thin film is a film formed by a method other than plating,
the copper-plated object is a object formed by plating using the copper thin film as a seed layer,
A chemical solution, the contact angle of the chemical solution on the surface of the copper-plated object when not in contact with the chemical solution being less than 100°. The chemical solution according to claim 1 or 2 , further comprising an anticorrosive agent (B). The chemical solution according to claim 1 , further comprising a surfactant (C). The chemical solution according to any one of claims 1 to 4 , wherein the oxoacid (A1a) contains phosphoric acid, or the peracid (A2) contains perphosphoric acid. a first liquid containing the acetic acid as the oxoacid (A1a) and water (W);
The chemical solution according to any one of claims 1 to 5 , which is a two-liquid type chemical solution consisting of a first liquid containing the peroxide (A1b) and a second liquid containing the peroxide (A1b). forming a copper thin film on a substrate;
forming a plating mold on the copper thin film;
copper plating the substrate having the mold thereon to form a copper-plated object in the mold;
peeling off the mold after the copper-plated object is formed;
and after peeling off the mold, etching the copper thin film using the chemical solution according to any one of claims 1 to 6 . The method for manufacturing a substrate provided with a copper-plated object according to claim 7 , wherein the copper thin film is formed on the substrate by physical vapor deposition.