JP2016135928A - Etchant for copper or copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etchant that causes less foaming at the time of use and enables highly selective etching of copper or a copper alloy in a step of etching copper or a copper alloy from an electronic substrate including copper or a copper alloy, and nickel at the same time.SOLUTION: An etchant for copper or copper alloy is used which is an etchant for a step of selectively etching copper or a copper alloy from an electronic substrate including copper or a copper alloy, and nickel at the same time, and contains, as essential components, a chain alkanolamine (A), a chelating agent (B) having acid radicals in the molecule, and hydrogen peroxide (C).SELECTED DRAWING: Figure 4

Description

  The present invention relates to an etching solution for etching copper or a copper alloy from an electronic substrate, and more particularly, etching for selectively etching copper or a copper alloy from an electronic substrate having electrodes (bumps) made of copper or a copper alloy and nickel. Regarding liquids.

  Electronic devices are being miniaturized and densified to improve performance, but in particular for semiconductor devices, miniaturization technology is approaching its limit. Devices with a three-dimensional structure have been put to practical use by using conventional wire bonding, flip chip and bump as a technology for increasing the density, but further higher density is desired. Therefore, development of a technique (TSV technique) in which a thin via penetrating through silicon is created and a conductor such as copper is filled to create an electrode is progressing (Non-Patent Document 1).

  Generally, when copper is used as an electrode in TSV technology, a hole is made in a silicon substrate, a barrier metal layer such as a silicon oxide film or titanium is formed on the inner wall of the hole, and then metal organic vapor phase epitaxy or physical vapor deposition is performed. A copper seed layer is formed by the method (FIG. 1). Next, a protective film is formed with a resist resin on the copper seed layer other than the portion where the electrode is to be formed (FIG. 2). Further, a metal such as copper is buried in a portion where the protective film is not formed, and bumps are formed. However, since the connection reliability is inferior due to a surface oxidation phenomenon or the like if copper remains as it is, generally a nickel layer and a solder layer made of an alloy of gold, tin and silver are respectively laminated (FIG. 3). Thereafter, the resist resin is removed to form bumps (FIG. 4).

  By the way, the copper seed layer and the barrier metal layer are formed not only inside the hole of the silicon substrate but also on the surface of the silicon substrate, and remain after the resist is removed. For this reason, it must be removed with an etchant (FIG. 5).

  Among these, as a method for wet etching a copper seed layer, a method using an etching solution composed of an acid and an oxidizing agent such as a mixed solution of sulfuric acid and hydrogen peroxide is widely used (Patent Document 1). A method using an etchant containing cupric chloride or ferric chloride is also widely known (Patent Document 2). Further, a method using an etching solution made of a surfactant which is sulfuric acid, hydrogen peroxide, and a polyethylene glycol derivative is also widely known (Patent Document 3).

  However, in the etching methods as described in Patent Documents 1 to 3, when the copper seed layer formed on the electronic substrate is etched after bump formation, the nickel used for bump formation is also etched, so that the bump is deformed. There was a problem.

Further, in the current etching apparatus, since the liquid level in the chemical solution buffer tank is detected and managed by the sensor, the generation of bubbles in the etching liquid causes the sensor to malfunction. In addition, since the etching solution is circulated by a pump, bubbles cause trouble in the liquid feeding because the pump bites air. For this reason, the etching method as in Patent Document 3 has a problem that bubbles are generated and workability is lacking.

12-16 pages of "TSV technology for 3D packaging" (Seiichi Hamada, 2009, published by Industrial Research Council)

JP 2000-286531 A JP 2008-285720 A JP 2009-120870 A

  The present invention relates to an etching solution capable of performing highly selective etching of copper or copper alloy with less foaming during use in the step of etching copper or copper alloy from an electronic substrate having copper or copper alloy and nickel simultaneously. The purpose is to provide.

The inventors of the present invention have reached the present invention as a result of studies to achieve the above object.
That is, the present invention is an etching solution for a process of selectively etching copper or a copper alloy from an electronic substrate having copper or a copper alloy and nickel at the same time, wherein the chain alkanolamine (A) and the acid group are contained in the molecule. And an etching solution for copper or copper alloy containing hydrogen peroxide (C) as essential components; and using this etching solution, selective from an electronic substrate having copper or copper alloy and nickel simultaneously And a method of manufacturing an electronic substrate, comprising the step of etching copper or a copper alloy.

  The present invention can etch copper or copper alloy with high selectivity in the step of etching copper or copper alloy from an electronic substrate having copper or copper alloy and nickel simultaneously.

FIG. 1 is a cross-sectional view in which a hole is formed in a silicon substrate, and a silicon oxide film, a titanium layer, and a copper seed layer are stacked on the inner wall of the hole. FIG. 2 is a cross-sectional view after applying a resist resin on the silicon substrate of FIG. 1 to form a protective film. 3 is a cross-sectional view after further laminating nickel and gold metals on the silicon substrate of FIG. FIG. 4 is a cross-sectional view after removing the resist resin from the silicon substrate of FIG. FIG. 5 is a cross-sectional view after removing the copper seed layer from the silicon substrate of FIG. 6 is a cross-sectional view after removing the barrier metal (titanium) layer from the silicon substrate of FIG.

  The etching solution for copper or copper alloy of the present invention is an etching solution for a process of selectively etching copper or copper alloy from an electronic substrate having copper or copper alloy and nickel at the same time, with less foaming during use, A chain alkanolamine (A), a chelating agent (B) having an acid group in the molecule, and hydrogen peroxide (C) are essential components.

  In the present invention, the electronic substrate having both copper or copper alloy to be etched and nickel at the same time includes those used for semiconductors and flat panel displays. Examples of copper include chemical vapor deposition (CVD), physical Examples include a vapor phase growth method (PVD method), an atomic layer deposition method (ALD method), and those formed by plating. Also, nickel formed by the above method can be used.

  The chain alkanolamine (A) that is the first essential component of the etching solution for copper or copper alloy of the present invention contains a hydroxyl group and one or more nitrogen atoms, and does not contain an alicyclic ring or a heterocyclic ring. It is an aliphatic alkanolamine, specifically, a chain alkanol monoamine (A1) represented by the following general formula (1) or a chain alkanol polyamine (A2) represented by the following general formula (2). It is done.

[In Formula (1), R ^{1 to} R ³ each independently represent a hydrogen atom or an alkyl group which may be partially substituted with a hydroxyl group. However, at least one of R ^{1 to} R ³ is an alkyl group substituted with a hydroxyl group. ]

[In formula (2), R ^{4 to} R ⁸ each independently represent a hydrogen atom or an alkyl group which may be partially substituted with a hydroxyl group. However, at least one of R ^{4 to} R ⁸ is an alkyl group substituted with a hydroxyl group. Y ¹ and Y ² each independently represent an alkylene group having 1 to 4 carbon atoms. n shows 0 or the integer of 1-4. ]

In the chain alkanol monoamine (A1) represented by the general formula (1), R ^{1 to} R ³ are a hydrogen atom, an alkyl group, or an alkyl group partially substituted with a hydroxyl group, each of which is the same or different. However, at least one of R ^{1 to} R ³ must be an alkyl group substituted with a hydroxyl group.

  Examples of the alkyl group include linear or branched ones having 1 to 5 carbon atoms. Specifically, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group. Etc.

  Examples of the alkyl group partially substituted with a hydroxyl group include linear or branched ones having 1 to 5 carbon atoms. Examples of the alkyl group partially substituted with a hydroxyl group include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, and a 3-hydroxypropyl group. 1-hydroxyisopropyl group, 2-hydroxyisopropyl group, dihydroxymethyl group, 1,1-dihydroxyethyl group, 1,2-dihydroxyethyl group, 2,3-dihydroxypropyl group, 1,2,3-trihydroxypropyl Group and the like.

In the chain polyamine (A2) represented by the general formula (2), R ^{4 to} R ⁸ are a hydrogen atom, an alkyl group, or an alkyl group partially substituted with a hydroxyl group, each of which is the same or different. However, at least one of R ^{4 to} R ⁸ must be an alkyl group substituted with a hydroxyl group.

The alkyl group and the alkyl group partially substituted with a hydroxyl group are the same as the alkyl group represented by R ^{1 to} R ³ and the alkyl group partially substituted with a hydroxyl group.

Examples of the alkylene group represented by Y1 and Y2 in the general formula (2) include linear or branched alkylene groups having 1 to 4 carbon atoms.
Specific examples include a methylene group, an ethylene group, a propylene group, a tetramethylene group, a butylene group, a 2,2-dimethylpropylene group, and a 2-ethylpropylene group.
The number of carbon atoms of the alkylene group represented by Y ¹ and Y ² is preferably 1 to 4, more preferably 1 to 3, and particularly preferably 2 from the viewpoint of suppressing foaming of the etching solution.

N in General formula (2) is 0 or an integer of 1-4, Preferably it is 0 or 1-2. The n [—Y ¹ —N (—R ⁸ ) —] may be the same or different.

  The chain alkanolamine (A) represented by the general formulas (1) and (2) preferably has an HLB of 12 to 45 from the viewpoint of suppressing foaming of the etching solution.

Here, “HLB” is an index indicating a balance between hydrophilicity and lipophilicity, and is described in, for example, “Introduction to Surfactants” (published by Sanyo Chemical Industries, Ltd., 2007, Takehiko Fujimoto), page 212. It is known as the calculated value by the Oda method, not the calculated value by the Griffin method.
The HLB value can be calculated from the ratio between the organic value and the inorganic value of the organic compound.
HLB≈10 × inorganic / organic The organic value and the inorganic value for deriving HLB can be calculated by using the values in the table described in “Introduction of Surfactant” on page 213.

  As the chain alkanol monoamine (A1), monoethanolamine, 2- (methylamino) ethanol, 2- (ethylamino) ethanol, 2- (isopropylamino) ethanol, 2-amino-2-methyl-1-propanol, 2- (dimethylamino) ethanol, 2- (diethylamino) ethanol, diethanolamine, triethanolamine, 3-amino-1-propanol, 1-amino-2-propanol, diisopropanolamine, triisopropanolamine and 3- (diethylamino) -1-propanol etc. are mentioned.

  Examples of the chain alkanol polyamine (A2) include 2-[(2-aminoethyl) amino] ethanol, 2- [methyl [2- (dimethylamino) ethyl] amino] ethanol, and 2,2 ′-(ethylenebisimino. ) Bisethanol, N- (2-hydroxyethyl) -N '-(2-aminoethyl) ethylenediamine, N- (3-hydroxypropyl) ethylenediamine, 2,2'-(2-aminoethylimino) diethanol, N- (2-hydroxyethyl) -N ′-(2-aminoethyl) ethylenediamine, 2- [bis (2-aminoethyl) amino] ethanol, 1- [2-[(2-aminoethyl) amino] ethyl] amino- 2-propanol, 3,3 ′, 3 ″, 3 ′ ″-[3-hydroxypropyliminobis (ethylenenitrilo)] tetrakis ( 1-propanol), N, N, N ′, N′-tetrakis (2-hydroxyethyl) ethylenediamine, N, N, N ′, N ′, N ″ -pentakis (2-hydroxypropyl) diethylenetriamine N, N, N ′, N′-tetrakis (2-hydroxyethyl) trimethylenediamine, N, N-bis (hydroxyethyl) diethylenetriamine, N1, N4-bis (hydroxyethyl) diethylenetriamine, N, N, N ′, N ′, N '' -Pentakis (2-hydroxypropyl) diethylenetriamine, N1- (2-hydroxypropyl) triethylenetetraamine, N4- (2-hydroxypropyl) triethylenetetraamine, N- (2-hydroxypropyl) triethylenetetraamine Etc.

  The etching agent of the present invention may be further diluted with water as required, but the content of the chain alkanolamine (A) is from the viewpoint of the etching rate ratio of copper or copper alloy and nickel, Based on the total weight of the etching solution at the time of use, it is preferably 0.05 to 6% by weight, more preferably 0.1 to 3% by weight, and particularly preferably 0.2 to 1.5% by weight.

  The chelating agent (B) having an acid group in the molecule, which is the second essential component of the present invention, has the effect of increasing the etching rate of copper or a copper alloy. The chelating agent (B) having an acid group in the molecule of the present invention has two or more functional groups for having a chelating effect, and if one or more of them are acid groups, The functional group may be an alcoholic hydroxyl group, a phenolic hydroxyl group, a nitrile group, a thiol group, an amino group, or the like. Examples of the acid group in the chelating agent (B) in the present invention include a carboxyl group, a phosphone group, a sulfone group, a phosphoric acid group, a sulfuric acid group, a nitric acid group, and a boric acid group. In addition, you may contain a chelating agent (B) in the form of a salt in etching liquid.

  As the chelating agent (B) or a salt thereof of the present invention, an organic acid or a salt thereof (B1) containing two or more carboxyl groups as an acid group, an organic acid or a salt thereof containing two or more phosphonic acid groups as an acid group ( B2), an organic acid having two or more sulfonic acid groups as an acid group or a salt thereof (B3), an organic acid having at least one carboxyl group or phosphonic acid group as an acid group, or a salt thereof (B4), etc. . Moreover, as a chelating agent (B) which has an acid group in a molecule | numerator, if it has a hydroxyl group which shows a chelate effect in a molecule | numerator, it will contain only one carboxyl group, a phosphonic acid group, or a sulfonic acid group as an acid group. Even a chelating agent (B5) can be used.

  Examples of the organic acid having two or more carboxyl groups as acid groups or a salt thereof (B1) include ethylenediaminetetraacetic acid (salt), diethylenetriaminepentaacetic acid (salt), triethylenetetraminehexaacetic acid (salt), hydroxyethylethylenediaminetriacetic acid ( Salt), dihydroxyethylethylenediaminetetraacetic acid (salt), nitriloacetic acid (salt), hydroxyethyliminodiacetic acid (salt), β-alanine diacetate (salt), aspartate diacetate (salt), methylglycine diacetate (salt) ), Iminodisuccinic acid (salt), serine diacetic acid (salt), hydroxyiminodisuccinic acid (salt), tartaric acid (salt), citric acid (salt), pyromellitic acid (salt), benzopolycarboxylic acid (salt), cyclo Examples include pentanetetracarboxylic acid (salt).

  Examples of the organic acid or salt (B2) containing two or more phosphonic acid groups as an acid group include methyldiphosphonic acid (salt), aminotri (methylenephosphonic acid) (salt), 1-hydroxyethylidene-1, 1-diphosphone Acid (salt), ethylenediaminetetra (methylenephosphonic acid) (salt), hexamethylenediaminetetra (methylenephosphonic acid) (salt), propylenediaminetetra (methylenephosphonic acid) (salt), diethylenetriaminepenta (methylenephosphonic acid) (salt) ), Triethylenetetramine hexa (methylenephosphonic acid) (salt), triaminotriethylamine hexa (methylenephosphonic acid) (salt), trans-1,2-cyclohexanediaminetetra (methylenephosphonic acid) (salt), glycol ether diaminetetra (Methylenephosphonic acid) (Salt , Tetraethylenepentamine hepta (methylene phosphonic acid) (salt), and the like.

  As an organic acid or a salt thereof (B3) containing two or more sulfonic acid groups as an acid group, methanedisulfonic acid (salt), ethanedisulfonic acid (salt), phenol disulfonic acid (salt), naphthalenedisulfonic acid (salt), And piperazine-1,4-bis (2-ethanesulfonic acid) (salt).

  Organic acids containing at least one carboxyl group and phosphonic acid group as acid groups or salts thereof (B4) include phosphonoacetic acid (salt), 2-hydroxy-2-phosphonoacetic acid (salt), and carboxyphosphonic acid (salt). , 3-phosphonopropionic acid (salt), 4- (3-phosphonopropyl) -2-piperazinecarboxylic acid (salt), and the like.

  As the chelating agent (B5) containing only one carboxyl group, phosphonic acid group or sulfonic acid group as a hydroxyl group and an acid group, lactic acid (salt), salicylic acid (salt), gallic acid (salt), 2-hydroxyethylphosphonic acid (Salt), 2-hydroxyethanesulfonic acid (salt), etc. are mentioned.

  Among the chelating agents (B) of the present invention, those preferable from the viewpoint of the etching rate of copper or copper alloy are the above (B1), (B2) and (B3), and more preferably (B2). .

  The chelating agent (B) having an acid group in the molecule can be used alone or in combination of two or more.

  The content of the chelating agent (B) having an acid group in the molecule is preferably from 0.1 to 50% by weight, more preferably from the viewpoint of the etching rate of copper or copper alloy, based on the total weight of the etching solution at the time of use. Is 0.5 to 30% by weight, particularly preferably 1 to 20% by weight.

  Hydrogen peroxide (C), which is the third essential component of the present invention, has the effect of increasing the etching rate. As the hydrogen peroxide (C), an aqueous solution of hydrogen peroxide can be used.

  The hydrogen peroxide (C) content is preferably 0.05 to 20% by weight, more preferably 0.1 to 10% in terms of pure content, based on the total weight of the etching solution at the time of use, from the viewpoint of the etching rate. % By weight, particularly preferably 0.2 to 5% by weight.

  The weight ratio (B) / (A) of the chain alkanolamine (A) of the present invention and the chelating agent (B) having an acid group in the molecule is from the viewpoint of the etching rate ratio of copper or copper alloy and nickel and foaming. Usually, it is 1-100, Preferably it is 2-50, More preferably, it is 5-30.

  The weight ratio (B) / (C) of the chelating agent (B) having an acid group in the molecule and hydrogen peroxide (C) of the present invention is usually 1 to 30, from the viewpoint of the etching rate of copper or copper alloy. Preferably it is 2-20, More preferably, it is 3-10.

The etching solution of the present invention is preferably used by mixing with (A), (B), (C) and, if necessary, a solvent. Examples of the solvent include water, alcohol, glycol ether, ether, ester, ketone, carbonate, amide and the like.
From the viewpoint of easy handling as a solvent for the etching solution, water is preferred.

  The etching solution of the present invention may contain a corrosion inhibitor such as triazoles, imidazoles, thiol compounds, sugar alcohols and the like as needed for the purpose of protecting the wiring metal.

  In the etching solution of the present invention, an antioxidant may be added as necessary for the purpose of protecting the wiring metal. Examples of the antioxidant include catechin, tocopherol, catechol, methyl catechol, ethyl catechol, tert-butyl catechol, phenols such as gallic acid, methyl gallate, propyl gallate, 3-hydroxyflavone, ascorbic acid and the like.

  A basic compound or an acidic compound can be added to the etching solution of the present invention for the purpose of pH adjustment. The basic compound added for that purpose is ammonia, amine or tetraalkylammonium hydroxide, nitrogen-containing heterocyclic compound. Examples of the amine include aliphatic amine, alkylene diamine, polyalkylene polyamine, aromatic amine, alicyclic amine, and guanidine. The acidic compound added for that purpose is an inorganic acid such as sulfuric acid, hydrochloric acid, nitric acid or hydrofluoric acid, or an organic acid such as acetic acid.

  In addition, it is effective to add an inorganic acid or a salt thereof for the purpose of stabilizing the etching rate. As such an inorganic acid, sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid and the like are preferable.

  An antifoaming agent can be added to the etching solution of the present invention as necessary for the purpose of protecting the wiring metal. Examples of the antifoaming agent include a silicone antifoaming agent, a long-chain alcohol defoaming agent, a fatty acid ester antifoaming agent, and a metal soap antifoaming agent. An ethylene oxide propylene oxide copolymer can also be used as an antifoaming agent.

  Using the etching solution of the present invention, an electronic substrate can be produced through a step of selectively etching copper or a copper alloy from an electronic substrate having copper or a copper alloy and nickel at the same time.

  In the present invention, examples of the etching treatment method for copper or copper alloy include immersion etching and single wafer etching.

  The etching solution of the present invention is usually used in a temperature range of 10 to 100 ° C, preferably 20 to 80 ° C. If it is 10 degreeC or more, it is preferable at the point of an etching rate, and if it is 100 degrees C or less, it is preferable at the point which does not produce variation in an etching rate.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

<Examples 1-7 and Comparative Examples 1-6>
Etching of the present invention by mixing the chain alkanolamine (A) described in Table 1, the chelating agent (B) having an acid group in the molecule, hydrogen peroxide (C), and water in a polypropylene container. An etching solution for comparison with the solution was obtained.

In addition, the symbol in a table | surface represents the following compounds.
(A-1): Triethanolamine (A-2): 2-[(2-aminoethyl) amino] ethanol (A-3): 1,2-bis [di (hydroxyethyl) amino] ethane (Sanyo Kasei) Kogyo Co., Ltd., trade name "SANNICS NE-240"
(A′-1): EO9 molar adduct of lauryl alcohol (B-1): citric acid (B-2): 60% aqueous solution of 1-hydroxyethylidene-1,1-diphosphonic acid (B-3): 1 , 2-ethanedisulfonic acid dihydrate (B-4): nitrilotrismethylenephosphonic acid (B′-1): ethylenediamine (C-1): 35% aqueous hydrogen peroxide

  As the performance evaluation, foam suppression, copper etching time, and nickel etching performance (nickel / copper etching rate ratio) were performed by the following methods.

<Foam suppression>
Antifoaming properties can be measured according to the Ross Miles test [JIS K3362 (1998)], and all of the tests using an apparatus defined by this JIS and an etching agent prepared using ultrapure water as a test solution. The height (mm) of the foam immediately after flowing out the test solution was visually measured, and the foam suppression property was evaluated according to the following criteria.
○: Less than 50 mm ×: 50 mm or more

<Copper etching time>
The copper etching time was evaluated by the time (minutes) until the gloss of the copper seed layer disappeared by the following operation method.
(1) A test piece was made by cutting a wafer (copper seed layer thickness 1 μm) prepared by processing a silicon substrate to the state of FIG. 4 into a 15 mm square.
When the cross section of the test piece obtained by cutting the wafer into 1 cm pieces was observed with a scanning electron microscope (S-4800 manufactured by Hitachi High-Tech), the bump width was about 30 μm and the bump height was about 8 μm. The thickness of the copper seed layer was 1 μm.
(2) The etching solution was put in a polypropylene container, and the test piece was immersed therein and stirred with a magnetic stirrer.
(3) The surface of the test piece is visually observed while immersed in the liquid while stirring, until the copper gloss of the entire copper seed layer disappears (3 in FIG. 5: the entire surface of the titanium layer is visible). Was measured.
In the etching solution used for this purpose, the disappearance time of copper luster is preferably within 10 minutes.
In addition, the thing which gloss did not lose | disappear in 60 minutes stopped immersion in 60 minutes, and described in Table 1 as ">60".

<Nickel etching amount and nickel / copper etching rate ratio>
The etching amount of nickel and the etching rate ratio of nickel / copper were measured and evaluated by the following operating methods.
(1) A test piece was made by cutting a wafer (copper seed layer thickness 1 μm) prepared by processing a silicon substrate to the state of FIG. 4 into a 15 mm square.
(2) The etching solution was put in a polypropylene container, and the test piece was immersed in the container for 1 minute and stirred with a magnetic stirrer, and then taken out.
(3) With a scanning electron microscope (S-4800, manufactured by Hitachi High-Tech), the side surface in which the degree of erosion of the nickel layer and the width of the test piece before immersion and the test piece after immersion were confirmed. Then, from the photograph image, the width A ₁ (μm) of the nickel layer (7 in FIG. 4) of the test piece before immersion and the width A ₂ (μm) of the nickel layer (7 in FIG. 5) after immersion. Was measured.
(4) As the nickel etching amount, the change (difference) ΔA _Ni in the width of the nickel layer of the test piece before and after the immersion calculated by the following mathematical formula (1) was calculated.

Evaluation is based on the following criteria.
○: Less than 1 μm × 1 μm or more (5) The two values read and the etching time of copper were substituted into the following formula (2) to calculate the nickel / copper etching rate ratio.

T _Cu : Etching time of copper (min)
T _Ni : Nickel etching time, 1 minute in this evaluation method A _Cu : Thickness of copper seed layer, 1 μm in this evaluation method

From the etching rate ratio of nickel / copper calculated by the above formula (2), evaluation was made according to the following criteria.
○: Less than 0.5
×: 0.5 or more

  As is clear from Table 1, in Examples 1 to 7, there was no problem with foaming and the copper seed layer was etched quickly. On the other hand, the nickel portion was not etched, and the copper seed layer was highly selectively formed. It was possible to etch.

On the other hand, neither the copper seed layer nor nickel is etched in Comparative Example 1 containing no hydrogen peroxide solution and Comparative Example 2 containing no chelating agent having an acid group in the molecule.
In Comparative Example 3 containing no chain alkanolamine, although the etching of the copper seed layer is fast, nickel is etched and the copper seed layer cannot be etched with high selectivity.
In Comparative Example 4 in which the EO9 molar adduct (A′-1) of lauryl alcohol was used instead of the chain alkanolamine (A), the copper seed layer was etched with high selectivity, but foaming increased.
Etching of the copper seed layer is also slow for Comparative Example 5 using the chelating agent (B′-1) having no acid group in the molecule.
In Comparative Example 6 using sulfuric acid instead of the chelating agent, nickel is etched.

  The etching solution for copper or copper alloy of the present invention has less foaming at the time of use with respect to an article having copper or copper alloy and nickel at the same time, and can etch copper or copper alloy with high selectivity. Therefore, it is useful as a chemical for a process in the production of electronic substrates such as printed wiring boards, flat panel displays, MEMS, and semiconductor devices.

The numbers 1-9 in FIGS. 1-6 represent the following.
1: Silicon substrate 2: Silicon oxide film 3: Titanium layer 4: Copper seed layer 5: Resist resin 6: Copper plating layer 7: Nickel plating layer 8: Gold plating layer 9: Bump

Claims (8)

  An etching solution for a process of selectively etching copper or a copper alloy from an electronic substrate having copper or a copper alloy and nickel at the same time, comprising a chain alkanolamine (A) and a chelating agent having an acid group in the molecule (B ), And hydrogen peroxide (C) as essential components, an etching solution for copper or copper alloy. The chain alkanolamine (A) is a chain alkanol monoamine (A1) represented by the following general formula (1) or a chain alkanol polyamine (A2) represented by the following general formula (2). Etching solution.
[In Formula (1), R ^{1 to} R ³ each independently represent a hydrogen atom or an alkyl group which may be partially substituted with a hydroxyl group. However, at least one of R ^{1 to} R ³ is an alkyl group substituted with a hydroxyl group. ]
[In formula (2), R ^{4 to} R ⁸ each independently represent a hydrogen atom or an alkyl group which may be partially substituted with a hydroxyl group. However, at least one of R ^{4 to} R ⁸ is an alkyl group substituted with a hydroxyl group. Y ¹ and Y ² each independently represent an alkylene group having 1 to 4 carbon atoms. n shows 0 or the integer of 1-4. ]   The etching solution according to claim 1 or 2, wherein the chain alkanolamine (A) has an HLB of 12 to 45.   The etching solution according to any one of claims 1 to 3, wherein the chelating agent (B) is an organic acid having a total of two or more phosphonic acid groups and / or sulfonic acid groups in the molecule.   The etching solution according to any one of claims 1 to 3, wherein the chelating agent (B) is an organic acid having two or more carboxyl groups in the molecule.   The etching solution according to any one of claims 1 to 5, wherein a weight ratio (B) / (A) of the chain alkanolamine (A) to the chelating agent (B) is 1 to 100.   The etching solution according to any one of claims 1 to 6, wherein a weight ratio (B) / (C) of the chelating agent (B) to hydrogen peroxide (C) is 1 to 30.   A step of selectively etching copper or a copper alloy from an electronic substrate having copper or a copper alloy and nickel simultaneously using the copper or copper alloy etching solution according to claim 1. A method for manufacturing an electronic substrate.