JP2022031737A - Photosensitive resin composition - Google Patents

Abstract

SOLUTION: To provide a photosensitive resin composition comprising an alkali-soluble resin (A) having structural units of formulae (a1), (a2) and (a3), a compound (B) having at least one ethylenically unsaturated double bond in each molecule, and a photoradical polymerization initiator (C).

EFFECT: Forming a resist with the inventive photosensitive resin composition allows a resist opening to be properly filled with molten solder when forming a micro-bump by the IMS process, allowing for the production of a suitable solder electrode such as the micro-bump.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a photosensitive resin composition.

The injection molding method (IMS method) is one of the methods for forming a solder electrode (solder bump). So far, a solder paste method or the like has been used as a method for forming a solder electrode on a substrate such as a wafer. However, these methods have restrictions such as difficulty in controlling the height of the solder bumps and the inability to freely select the solder composition. On the other hand, the IMS method is known to have the advantage of not having these restrictions.

As shown in Patent Documents 1 to 4, the IMS method is a method characterized in that solder is poured into an opening of a resist while a nozzle capable of injection molding the molten solder is brought into close contact with the resist.

Japanese Unexamined Patent Publication No. 06-055260 Japanese Unexamined Patent Publication No. 2007-294954 Japanese Unexamined Patent Publication No. 2007-294959 Japanese Patent Publication No. 2013-52011

In order to form microbumps by the IMS method, it is necessary to inject and fill the narrow and deep resist openings with the molten solder, but it is difficult to completely fill the narrow and deep openings with the molten solder. Further, it is necessary to form a plurality of micro bumps, and in that case, a resist having a plurality of openings is formed, but it is difficult to make the size and shape of the plurality of openings uniform. Therefore, depending on the size and shape of the opening, there is a tendency that some openings can be completely filled with the molten solder and some openings cannot be completely filled with the molten solder.

For the above reasons, when forming microbumps by the IMS method, it may not be possible to completely fill the resist openings with molten solder, and it may not be possible to form microbumps suitable for the purpose. There is a problem.

An object of the present invention is to use the resist in the process of producing a solder electrode such as a microbump suitable for the purpose by satisfactorily filling the resist opening with molten solder when forming the microbump by the IMS method. It is an object of the present invention to provide a photosensitive resin composition which can be suitably used when forming.

The present invention that achieves the above object relates to, for example, the following [1] to [11].
[1] An alkali-soluble resin (A) having a structural unit (a1) represented by the following formula (a1) on a substrate having an electrode pad, and a compound having at least one ethylenically unsaturated double bond in one molecule. Step (1) of forming a coating film of a photosensitive resin composition containing (B) and a photoradical polymerization initiator (C);
A step (2) of forming a resist having an opening in a region corresponding to the electrode pad by selectively exposing and further developing the coating film; and by an injection molding method inside the opening of the resist. Step of filling molten solder (4);
A method for manufacturing a solder electrode, which comprises.

（式（ａ１）中、Ｒ¹はそれぞれ独立に水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示し；Ｒ²は置換基を有していてもよい１価の脂環式炭化水素基を示す。）

(In formula (a1), R ¹ represents an independently hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ² may have a substituent 1 Indicates an alicyclic hydrocarbon group of valence.)

[2] The method for producing a solder electrode according to the above [1], wherein the alkali-soluble resin (A) has a structural unit represented by the following formula (a2).

（式（ａ２）中、Ｒ³は水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示し；Ｒ⁴はアルキル基の少なくとも１つ以上の水素原子を水酸基またはアルコキシ基に置換した基を示す。）

(In formula (a2), R ³ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ⁴ represents at least one hydrogen atom of the alkyl group as a hydroxyl group or a hydroxyl group. Indicates a group substituted with an alkoxy group.)

[3] The method for producing a solder electrode according to the above [1] or [2], wherein the alkali-soluble resin (A) has a structural unit represented by the following formula (a3).

（式（ａ３）中、Ｒ⁵は水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示し；Ｒ⁶は単結合、－ＯＣＯ－、－ＣＯＯ－、－ＣＯＮＨ－、または－Ｏ－を示し；Ｒ⁷はフェノール性水酸基を有するアリール基を示す。）

(In formula (a3), R ⁵ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ⁶ is a single bond, -OCO-, -COO-, -CONH. -Or -O-; R ⁷ indicates an aryl group having a phenolic hydroxyl group.)

[4] The method for producing a solder electrode according to any one of the above [1] to [3], wherein the content ratio of the structural unit (a1) contained in the alkali-soluble resin (A) is 15 to 60% by mass. ..
[5] Any of the above [1] to [4], which comprises the step (3) of forming a plating film inside the opening of the resist after the step (2) and before the step (4). The method for manufacturing a solder electrode described in the above.
[6] An alkali-soluble resin (A) having 15 to 60% by mass of the structural unit (a1) represented by the following formula (a1) and 15 to 50% by mass of the structural unit represented by the following formula (a2) in one molecule. A photosensitive resin composition containing a compound (B) having at least one ethylenically unsaturated double bond and a photoradical polymerization initiator (C).

（式（ａ１）中、Ｒ¹はそれぞれ独立に水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示し；Ｒ²は置換基を有していてもよい１価の脂環式炭化水素基を示す。）

(In formula (a1), R ¹ represents an independently hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ² may have a substituent 1 Indicates an alicyclic hydrocarbon group of valence.)

（式（ａ２）中、Ｒ³は水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示し；Ｒ⁴はアルキル基の少なくとも１つ以上の水素原子を水酸基またはアルコキシ基に置換した基を示す。）

(In formula (a2), R ³ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ⁴ represents at least one hydrogen atom of the alkyl group as a hydroxyl group or a hydroxyl group. Indicates a group substituted with an alkoxy group.)

[7] The photosensitive resin composition according to the above [6], wherein the alkali-soluble resin (A) has a structural unit represented by the following formula (a3).

（式（ａ３）中、Ｒ⁵は水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示し；Ｒ⁶は単結合、－ＯＣＯ－、－ＣＯＯ－、－ＣＯＮＨ－、または－Ｏ－を示し；Ｒ⁷はフェノール性水酸基を有するアリール基を示す。）

(In formula (a3), R ⁵ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ⁶ is a single bond, -OCO-, -COO-, -CONH. -Or -O-; R ⁷ indicates an aryl group having a phenolic hydroxyl group.)

[8] An alkali-soluble resin (A) having a structural unit (a1) represented by the following formula (a1) on a substrate having an electrode pad, and a compound having at least one ethylenically unsaturated double bond in one molecule. Step (1) of forming a coating film of a photosensitive resin composition containing (B) and a photoradical polymerization initiator (C);
A step (2) of forming a resist having an opening in a region corresponding to the electrode pad by selectively exposing the coating film and further developing the coating film.
A step (4) of filling the inside of the opening of the resist with molten solder by an injection molding method to form a solder electrode; and a first having an electrode pad of the first substrate and an electrode pad via the solder electrode. 2 Step of forming an electrical connection structure with the electrode pad of the substrate (6);
A method for producing a laminated body, which comprises.

（式（ａ１）中、Ｒ¹はそれぞれ独立に水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示し；Ｒ²は置換基を有していてもよい１価の脂環式炭化水素基を示す。）

(In formula (a1), R ¹ represents an independently hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ² may have a substituent 1 Indicates an alicyclic hydrocarbon group of valence.)

[9] An alkali-soluble resin (A) having a structural unit (a1) represented by the following formula (a1) on a substrate having an electrode pad, and a compound having at least one ethylenically unsaturated double bond in one molecule. Step (1) of forming a coating film of a photosensitive resin composition containing (B) and a photoradical polymerization initiator (C);
A step (2) of forming a resist having an opening in a region corresponding to the electrode pad by selectively exposing the coating film and further developing the coating film.
A step of filling the inside of the opening of the resist with molten solder by an injection molding method to form a solder electrode (4);
The step of removing the resist (5); and the step of forming an electrical connection structure between the electrode pad of the first substrate and the electrode pad of the second substrate having the electrode pad via the solder electrode (6). ;
A method for producing a laminated body, which comprises.

（式（ａ１）中、Ｒ¹はそれぞれ独立に水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示し；Ｒ²は置換基を有していてもよい１価の脂環式炭化水素基を示す。）

(In formula (a1), R ¹ represents an independently hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ² may have a substituent 1 Indicates an alicyclic hydrocarbon group of valence.)

[10] A laminate produced by the method for producing a laminate according to the above [8] or [9].
[11] An electronic component having the laminate according to the above [10].

According to the method for manufacturing a solder electrode of the present invention, by forming a resist using a specific photosensitive resin composition, when microbumps are formed by the IMS method, the resist openings are satisfactorily filled with molten solder. It is possible to manufacture a solder electrode such as a micro bump suitable for the purpose.

FIG. 1 is a diagram showing a state in which a coating film of a photosensitive resin composition is formed on a substrate by the step (1) in the method for manufacturing a solder electrode of the present invention. FIG. 2 is a diagram showing a state in which a resist is formed by the step (2) in the method for manufacturing a solder electrode of the present invention. FIG. 3 is a diagram showing a state in which a plating film is formed inside the opening of the resist by the step (3) in the method for manufacturing a solder electrode of the present invention. FIG. 4 (1) is a diagram showing a state in which molten solder is filled inside a resist opening by an injection molding method in the method (4) of the method for manufacturing a solder electrode of the present invention. FIG. 4 (2) is a diagram showing a state in which a solder electrode is formed by the step (4) in the method for manufacturing a solder electrode of the present invention. FIG. 5 (1) is a diagram showing the state of the first substrate and the second substrate before forming the electrical connection structure in the step (6) in the method for manufacturing the first laminated body of the present invention. FIG. 5 (2) shows a state in which an electrical connection structure between the electrode pad of the first substrate and the electrode pad of the second substrate is formed by the step (6) in the method of manufacturing the first laminated body of the present invention. It is a figure. FIG. 6 is a diagram showing a state in which the resist is removed from the substrate provided with the solder electrode by the step (5) in the method for manufacturing the second laminated body of the present invention. FIG. 7 (1) is a diagram showing the state of the first substrate and the second substrate before forming the electrical connection structure in the step (6) in the method for manufacturing the second laminated body of the present invention. FIG. 7 (2) shows a state in which an electrical connection structure between the electrode pad of the first substrate and the electrode pad of the second substrate is formed by the step (6) in the method for manufacturing the second laminated body of the present invention. It is a figure.

[Manufacturing method of solder electrodes]
The method for manufacturing a solder electrode of the present invention is
An alkali-soluble resin (A) having a structural unit (a1) represented by the following formula (a1) on a substrate having an electrode pad, and a compound (B) having at least one ethylenically unsaturated double bond in one molecule. , And the step of forming a coating film of the photosensitive resin composition containing the photoradical polymerization initiator (C) (1);
A step (2) of forming a resist having an opening in a region corresponding to the electrode pad by selectively exposing and further developing the coating film; and by an injection molding method inside the opening of the resist. Step of filling molten solder (4);
It is characterized by having.

（式（ａ１）中、Ｒ¹はそれぞれ独立に水素原子、または置換基を有してもよい炭素数１～１０のアルキル基を示し；Ｒ²は置換基を有してもよい１価の脂環式炭化水素基を示す。）

(In formula (a1), R ¹ represents an independently hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent; R ² is a monovalent group which may have a substituent. Indicates an alicyclic hydrocarbon group.)

Hereinafter, the method for manufacturing the solder electrode of the present invention will be described with reference to the drawings.
(Step 1)
In step 1, as shown in FIG. 1, a coating film 3 of a photosensitive resin composition is formed on a substrate 1 having an electrode pad 2.
The substrate 1 is, for example, a semiconductor substrate, a glass substrate, a silicon substrate, and a substrate formed by providing various metal films or the like on the surfaces of the semiconductor plate, the glass plate, and the silicon plate. The substrate 1 has a large number of electrode pads 2.

The coating film 3 is formed by applying a photosensitive resin composition to the substrate 1 or the like. The method for applying the photosensitive resin composition is not particularly limited, and examples thereof include a spray method, a roll coating method, a spin coating method, a slit die coating method, a bar coating method, and an inkjet method. The film thickness of the coating film 3 is usually 0.001 to 100 μm, preferably 0.01 to 50 μm, and more preferably 0.1 to 10 μm.

The photosensitive resin composition is an alkali-soluble resin (A) having a structural unit (a1) represented by the above formula (a1), and a compound (B) having at least one ethylenically unsaturated double bond in one molecule. , And a photoradical polymerization initiator (C).

In the formula (a1) showing the structural unit (a1) of the alkali-soluble resin (A), the two ^R1s are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. Is shown. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an n-butyl group and the like.

R ² represents a monovalent alicyclic hydrocarbon group which may have a substituent. Examples of the alicyclic hydrocarbon group include a cyclohexyl group, a phenyl group, a naphthyl group, a benzyl group and the like. Of these, the cyclohexyl group is particularly preferred.

Examples of the monomer capable of forming the structural unit (a1) include N-cyclohexylmaleimide, N-phenylmaleimide, N- (4-aminophenyl) maleimide, N-benzylmaleimide, and N- (9-acridinyl) maleimide. Can be mentioned.

In the method for producing a solder electrode of the present invention, a resist formed from a photosensitive resin composition containing an alkali-soluble resin (A) having the structural unit (a1) is used to form microbumps by an IMS method. At that time, the resist opening can be satisfactorily filled with molten solder, and a solder electrode such as a micro bump suitable for the purpose can be manufactured. The reason why such an effect can be obtained is considered as follows.

The present inventor finds it difficult to completely fill the resist opening with the molten solder when forming microbumps by the IMS method because of the outgas generated from the resist when the IMS method is performed. We obtained the finding that there is only one. That is, it is considered that outgas is generated from the resist due to the heat applied when the IMS method is performed, and this gas stays in the resist opening to prevent the molten solder from flowing into the resist opening. As the amount of outgas generated increases, it becomes difficult for the molten solder to flow into the resist opening, and it becomes difficult to sufficiently fill the resist opening with the molten solder.

Microbumps often have a pillar-like structure with the lower part made of copper and the upper part made of solder. When manufacturing such a pillar-shaped bump, it is common to first fill the resist opening with copper and then copper-plat the substrate. Therefore, the resist is required to have plating resistance. It is known that the plating resistance increases as the glass transition temperature of the resin constituting the resist increases. For this reason, polycyclic fused aliphatic methacrylates such as dicyclopentanyl acrylate, which are generally known to have a high glass transition temperature, are used in conventional photosensitive resin compositions used for forming resists. A resin containing a structural unit derived from was used.

However, in a resin containing a structural unit derived from a polycyclic condensed ring aliphatic methacrylate, the ester moiety of the structural unit is easily decomposed by heat, and the component released by the decomposition is released as a gas. When microbumps are formed by the IMS method using a resist formed from a conventional photosensitive resin composition, it is not possible to satisfactorily fill the resist openings with molten solder because of the polycyclic condensed ring aliphatic group. It is considered that this is because the ester moiety of the structural unit derived from methacrylate is decomposed by heat and a large amount of the component released by the decomposition is released as outgas.

The structural unit (a1) contained in the alkali-soluble resin (A) contained in the photosensitive resin composition used in the method for producing a solder electrode of the present invention is not easily decomposed by heat. Therefore, when the IMS method is performed using a resist formed from this photosensitive resin composition, the amount of outgas generated from the resist is small, and the degree to which the outgas prevents the molten solder from flowing into the resist opening is low. .. For the above reasons, according to the method for manufacturing a solder electrode of the present invention, the resist opening can be satisfactorily filled with molten solder by the IMS method, and a solder electrode such as a micro bump suitable for the purpose can be manufactured. It is thought that it can be done.

Further, since the alkali-soluble resin (A) having the structural unit (a1) has a high glass transition temperature, the resist formed from the photosensitive resin composition containing the alkali-soluble resin (A) has high plating resistance.

That is, the photosensitive resin composition has an effect of achieving both good filling of the molten solder and high plating resistance by suppressing the generation of outgas.
The content ratio of the structural unit (a1) contained in the alkali-soluble resin (A) is preferably 15 to 60% by mass, more preferably 20 to 50% by mass, and further preferably 25 to 45% by mass. When the content ratio of the structural unit (a1) is at least the lower limit value, it is advantageous in that high plating resistance can be obtained and the generation of outgas can be reduced. On the other hand, if the content ratio of the structural unit (a1) becomes too high, the resist forming ability may decrease. Therefore, in order to secure the resist forming ability, the content ratio of the structural unit (a1) is equal to or less than the upper limit value. It is advantageous to be.

The alkali-soluble resin (A) preferably contains the structural unit represented by the following formula (a2). When the alkali-soluble resin (A) contains the structural unit represented by the formula (a2), it is possible to prevent the substrate from warping during the implementation of the IMS method, and it is also possible to suppress the generation of outgas.

式（ａ２）中、Ｒ³は水素原子、または炭素数１～１０の置換基を有してもよいアルキル基を示す。前記アルキル基としては、メチル基、エチル基、プロピル基、ｎ－ブチル基等が挙げられる。

In formula (a2), R ³ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an n-butyl group and the like.

R ⁴ represents a group formed by substituting at least one hydrogen atom of an alkyl group with a hydroxyl group or an alkoxy group. Examples of R ⁴ include a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, a methoxyethyl group and the like.

Examples of the monomer capable of forming the structural unit (a2) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and methoxyethyl (meth) acrylate. Can be mentioned.

The content ratio of the structural unit (a2) contained in the alkali-soluble resin (A) is preferably 15 to 50% by mass, more preferably 10 to 40% by mass, and further preferably 20 to 35% by mass.

The alkali-soluble resin (A) preferably contains the structural unit represented by the following formula (a3). When the alkali-soluble resin (A) contains the structural unit represented by the formula (a3), the plating resistance of the resist is improved.

式（ａ３）中、Ｒ⁵は水素原子、または炭素数１～１０の置換基を有していてもよいアルキル基を示す。前記アルキル基としては、メチル基、エチル基、プロピル基、ｎ－ブチル基等が挙げられる。

In formula (a3), R ⁵ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an n-butyl group and the like.

R ⁶ represents a single bond, -OCO-, -COO-, -CONH-, or -O-.
R ⁷ represents an aryl group having a phenolic hydroxyl group. Examples of R ⁷ include a hydroxyphenyl group and a hydroxynaphthyl group.

Examples of the monomer capable of forming the structural unit (a3) include 4- (1-methylethenyl) phenol, 4-hydroxyphenyl (meth) acrylate, 4-hydroxy-1-vinylnaphthalene and the like.

The content ratio of the structural unit (a3) contained in the alkali-soluble resin (A) is preferably 5 to 30% by mass, more preferably 10 to 25% by mass.
The alkali-soluble resin (A) may contain structural units other than the structural units represented by the formulas (a1) to (a3). Other structural units include (meth) acrylic acid, methyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobornyl (meth) acrylate, n-butyl (meth) acrylate, styrene, crotonic acid, etc. A structural unit derived from maleic acid or the like can be mentioned.

The content of the alkali-soluble resin (A) in the photosensitive resin composition is preferably 20 to 60% by mass, more preferably 25 to 50% by mass.
The compound (B) having at least one ethylenically unsaturated double bond in one molecule is a component that is radically polymerized by an active species generated from a photoradical polymerization initiator by exposure.

As the compound (B), a (meth) acrylate compound having a (meth) acryloyl group and a compound having a vinyl group are preferable. The (meth) acrylate compound is classified into a monofunctional (meth) acrylate compound and a polyfunctional (meth) acrylate compound, and may be any compound.

Examples of the monofunctional (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate.
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, Isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, Isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl amyl (meth) acrylate, lauryl (meth) acrylate, octadecyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate. , Phenoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, glycerol (meth) acrylate, ethylene glycol monomethyl ether (meth) acrylate, ethylene glycol monoethyl ether (meth) acrylate, polyethylene glycol mono (Meta) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) Acrylate, phenoxypolypolyglycol glycol (meth) acrylate, tricyclo [5.2.1.0 ^2,6 ] decadienyl (meth) acrylate, tricyclo [5.2.1.0 ^2,6 ] decanyl (meth) acrylate, tricyclo [ 5.2.1.0 ^2,6 ] Decenyl (meth) acrylate, isobornyl (meth) acrylate, bornyl (meth) acrylate, cyclohexyl (meth) acrylate, acrylic acid amide, methacrylic acid amide, diacetone (meth) acrylamide, iso Butoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, tert-octyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylami Examples thereof include noethyl (meth) acrylate and 7-amino-3,7-dimethyloctyl (meth) acrylate.

Examples of the polyfunctional (meth) acrylate compound include trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane PO (propylene oxide) modified tri (meth) acrylate, and tetramethylol propane. Tetra (meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (Meta) acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, tris (2-hydroxy) Ethyl) isocyanurate tri (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, epoxy (meth) acrylate in which (meth) acrylic acid is added to diglycidyl ether of bisphenol A, bisphenol A di (meth) acryloyl. Oxyethyl ether, bisphenol A di (meth) acryloyl oxymethyl ethyl ether, bisphenol A di (meth) acryloyl oxyethyl oxyethyl ether, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta ( Examples thereof include meta) acrylate, dipentaerythritol hexa (meth) acrylate, polyester (meth) acrylate (trifunctional or higher), and a reaction product of phthalic acid and epoxy acrylate.

As the compound (B), a commercially available compound can be used as it is. Examples of commercially available compounds include Aronix M-210, M-309, M-310, M-320, M-400, M-7100, M-8030, and M-8060. Same M-8100, Same M-9050, Same M-240, Same M-245, Same M-6100, Same M-6200, Same M-6250, Same M-6300, Same M-6400, Same M-6500 (Same M-8100, Same M-9050, Same M-240, Same M-245, Same M-6100, Same M-6200, Same M-6250, Same M-6300, Same M-6400 As mentioned above, Toagosei Co., Ltd.), KAYARAD R-551, R-712, TMPTA, HDDA, TPGDA, PEG400DA, MANDA, HX-220, HX-620, R-604, DPCA-20, DPCA-30, DPCA-60, DPCA-120 (all manufactured by Nippon Kayaku Co., Ltd.), Viscort # 295, 300, 260, 312, 335HP, 360, 360. GPT, 3PA, 400 (all manufactured by Osaka Organic Chemical Industry Co., Ltd.) and the like can be mentioned.

These compounds (B) may be used alone or in combination of two or more.
The content of the compound (B) in the photosensitive resin composition is preferably 30 to 100 parts by mass, more preferably 40 to 80 parts by mass with respect to 100 parts by mass of the alkali-soluble resin (A).

The photoradical polymerization initiator (C) is a compound that generates radicals by irradiation with light to initiate radical polymerization of compound (B). As the photoradical polymerization initiator (C), a photoradical polymerization initiator having an oxime ester structure is preferable in that it has a function of generating a large amount of various active species and suppressing inhibition by oxygen in the air.

The photoradical polymerization initiator having an oxime ester structure may contain geometric isomers due to the double bond of the oxime, but these are not distinguished and any photoradical polymerization initiator may be used.

Examples of the photoradical polymerization initiator (C) include WO2010 / 146883A, Japanese Patent Application Laid-Open No. 2011-132215, Japanese Patent Application Laid-Open No. 2008-506749, Japanese Patent Laid-Open No. 2009-519904, and Japanese Patent Application Laid-Open No. 2009-519991. Described photoradical polymerization initiators are mentioned.

Specific examples of the photoradical polymerization initiator (C) include N-benzoyloxy-1- (4-phenylsulfanylphenyl) butane-1-on-2-imine and N-ethoxycarbonyloxy-1-phenylpropane-. 1-on-2-imine, N-benzoyloxy-1- (4-phenylsulfanylphenyl) octane-1-on-2-imine, N-acetoxy-1- [9-ethyl-6- (2-methylbenzoyl) ) -9H-Carbazole-3-yl] ethane-1-imine, and N-acetoxy-1- [9-ethyl-6- {2-methyl-4- (3,3-dimethyl-2,4-dioxa) Cyclopentanylmethyloxy) benzoyl} -9H-carbazole-3-yl] ethane-1-imine, etanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-yl]- , 1- (O-acetyloxime) and the like.

These compounds (C) may be used alone or in combination of two or more.
The content of the compound (C) in the photosensitive resin composition is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass with respect to 100 parts by mass of the alkali-soluble resin (A).

The photosensitive resin composition contains, as other components, a polymerization inhibitor, a chain transfer agent, a solvent, a surfactant, an adhesive aid, a sensitizer, an inorganic filler, etc., as long as the object and properties of the present invention are not impaired. It may be contained.

When the photosensitive resin composition contains a solvent, the handleability is improved, the viscosity can be easily adjusted, and the storage stability is improved.
As a solvent,
Alcohols such as methanol, ethanol and propylene glycol;
Cyclic ethers such as tetrahydrofuran and dioxane;
Glycols such as ethylene glycol and propylene glycol;
Alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether;
Alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate;
Aromatic hydrocarbons such as toluene and xylene;
Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone;
Ethyl acetate, butyl acetate, ethyl ethoxyacetate, ethyl hydroxyacetate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, 3 -Esters such as ethyl methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, ethyl lactate;
N-Methylformamide, N, N-dimethylformamide, N-methylformamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, benzylethyl ether, dihexyl ether, acetonylacetone, isophorone , Caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, γ-butyrolactone, ethylene carbonate, propylene carbonate, phenylcellosolve acetate and the like.

The solvent may be used alone or in combination of two or more.
When forming a resist having a film thickness of 0.1 to 100 μm, the solvent content is usually such that the solid content of the photosensitive resin composition is 5 to 80% by mass. The solid content means a component of all the components contained in the composition excluding the solvent.

(Step 2)
In step 2, as shown in FIG. 2, the coating film 3 is selectively exposed and further developed to form a resist 5 having an opening 4 in a region corresponding to the electrode pad 2. That is, the coating film 3 is partially exposed so that the opening 4 for accommodating each electrode pad 2 is formed, and then the coating film 3 is developed and heated to open the opening 4 for accommodating each electrode pad 2. Form. As a result, a resist 5 having an opening 4 in the region corresponding to each electrode pad 2 is obtained. The opening 4 is a hole that penetrates the resist 5. Exposure, development and heating can be performed according to the conventional method. The maximum width of the opening 4 is usually 0.1 to 10 times, preferably 0.5 to 2 times the film thickness of the coating film 3.

(Step 4)
In step 4, the inside of the opening 4 of the resist 5 is filled with molten solder by an injection molding method (IMS method).
First, as shown in FIG. 4 (1), the molten solder 9 is injected into the opening 4 from the IMS head 8 while the IMS head 8 is in close contact with the resist 5, preferably pressed. After that, by cooling, a solder electrode 6 is formed in each opening 4 as shown in FIG. 4 (2). In the IMS method, filling is usually performed while heating the molten solder to 250 ° C. or higher.

As described above, since the structural unit (a1) contained in the alkali-soluble resin (A) contained in the photosensitive resin composition forming the resist 5 is not easily decomposed by heat, the amount of outgas generated from the resist 5 in the step 4 is small. Therefore, the molten solder 9 can be satisfactorily filled in the opening 4, so that the solder electrode 6 suitable for the purpose is manufactured.
In the method for manufacturing a solder electrode of the present invention, the following step 3 can be performed after the step (2) and before the step (4).

(Step 3)
In step 3, as shown in FIG. 3, a plating film 15 is formed inside the opening 4 of the resist 5. As a method for forming the plating film 15, a normal plating method such as an electrolytic plating method can be used. The type of the plating film 15 is not particularly limited as long as it can form a solder electrode, and examples thereof include a copper film.

As described above, the alkali-soluble resin (A) contained in the photosensitive resin composition forming the resist 5 has a high glass transition temperature, and the resist 5 formed from the photosensitive resin composition has a high plating resistance. Therefore, the plating process can be performed satisfactorily in step 3.

By performing the step 3 after the step (2) and then performing the step (4), a pillar-shaped solder whose lower portion is made of a metal such as copper and whose upper portion is made of solder is placed on the metal pad of the substrate. Electrodes can be manufactured.

[Manufacturing method of laminated body]
The method for producing the first laminated body of the present invention is as follows.
An alkali-soluble resin (A) having a structural unit (a1) represented by the following formula (a1) on a first substrate having an electrode pad, and a compound having at least one ethylenically unsaturated double bond in one molecule ( Step (1) of forming a coating film of a photosensitive resin composition containing B) and a photoradical polymerization initiator (C);
A step (2) of forming a resist having an opening in a region corresponding to the electrode pad by selectively exposing the coating film and further developing the coating film.
A step (4) of filling the inside of the opening of the resist with molten solder by an injection molding method to form a solder electrode; and a first having an electrode pad of the first substrate and an electrode pad via the solder electrode. 2 Step of forming an electrical connection structure with the electrode pad of the substrate (6);
Have.

（式（ａ１）中、Ｒ¹はそれぞれ独立に水素原子、または炭素数１～１０の置換可能なアルキル基を示し；Ｒ²は置換可能な１価の脂環式炭化水素基を示す。）

(In formula (a1), R ¹ independently represents a hydrogen atom or a substitutable alkyl group having 1 to 10 carbon atoms; R ² represents a substitutable monovalent alicyclic hydrocarbon group.)

The method for producing the second laminated body of the present invention is as follows.
An alkali-soluble resin (A) having a structural unit (a1) represented by the following formula (a1) on a first substrate having an electrode pad, and a compound having at least one ethylenically unsaturated double bond in one molecule ( Step (1) of forming a coating film of a photosensitive resin composition containing B) and a photoradical polymerization initiator (C);
A step (2) of forming a resist having an opening in a region corresponding to the electrode pad by selectively exposing the coating film and further developing the coating film.
A step of filling the inside of the opening of the resist with molten solder by an injection molding method to form a solder electrode (4);
The step of removing the resist (5); and the step of forming an electrical connection structure between the electrode pad of the first substrate and the electrode pad of the second substrate having the electrode pad via the solder electrode (6). ;
Have.

（式（ａ１）中、Ｒ¹はそれぞれ独立に水素原子、または炭素数１～１０の置換可能なアルキル基を示し；Ｒ²は置換可能な１価の脂環式炭化水素基を示す。）

(In formula (a1), R ¹ independently represents a hydrogen atom or a substitutable alkyl group having 1 to 10 carbon atoms; R ² represents a substitutable monovalent alicyclic hydrocarbon group.)

The steps (1), (2) and (4) in the method for manufacturing the first and second laminates are substantially the same as the steps (1), (2) and (4) in the method for manufacturing the solder electrode. It is the same. That is, the method for manufacturing the first laminated body is a method in which the step (6) is performed after the steps (1), (2), and (4) in the method for manufacturing the solder electrode, and the second laminated body is manufactured. The method is a method in which the steps (5) and (6) are performed after the steps (1), (2), and (4) in the method for manufacturing the solder electrode.

In both the first and second laminated body manufacturing methods, in the solder electrode manufacturing method as in the case of the solder electrode manufacturing method, after the step (2) and before the step (4). The step (3) can be performed.

In the method for manufacturing the first and second laminates, the substrate in the method for manufacturing the solder electrode corresponds to the first substrate.
In the method for manufacturing the first laminate, after the steps (1), (2), and (4), the electrode pad of the first substrate and the electrode of the second substrate having the electrode pad are interposed via the solder electrode. The step (6) of forming an electrical connection structure with the pad is performed.

The second substrate used in the step (6) may be the same as the first substrate, that is, the substrate in the method for manufacturing the solder electrode.
In the step (6), for example, as shown in FIG. 5 (1), the adhesive 7 is applied to the surface of the second substrate 11 having the electrode pad 12. Then, the first substrate having the solder electrode 6 is opposed to each other so that the electrode pads 12 of the second substrate 11 face each of the solder electrodes 6 of the first substrate 1. The electrode pad 12 of the second substrate 11 is provided at a position facing the solder electrode 6 of the first substrate 1 at this time. After that, the first substrate 1 is placed on the second substrate 11 so that the solder electrode 6 is in contact with the electrode pad 12, and the solder electrode 9 is heated and / or crimped to obtain the solder electrode 9 as shown in FIG. 5 (2). An electrical connection structure is formed in which the electrode pad 2 of the first substrate 1 and the electrode pad 12 of the second substrate are connected to each other. As a result, the laminated body 10 having an electrical connection structure is manufactured. The laminate 10 includes an adhesive layer 13 formed from the adhesive 7.

The heating temperature is usually 100 to 300 ° C., and the crimping force is usually 0.1 to 10 MPa.
The adhesive 7 may be an adhesive used for laminating ordinary semiconductor elements. In the step (6), it is not necessary to use an adhesive.

The method for manufacturing the second laminate is a step (5) for removing the resist after the steps (1), (2), and (4), and an electrode pad of the first substrate via the solder electrode. And (6) to form an electrical connection structure with the electrode pad of the second substrate having the electrode pad.

The resist may be removed in the step (5) by a conventionally used resist removing method, and examples thereof include a wet process using a stripping solution and a dry process using ashing. FIG. 6 shows a state in which the resist 5 is removed from the first substrate 1.

The step (6) in the method for manufacturing the second laminate may be performed in the same manner as the step (6) in the method for manufacturing the first laminate. For example, as shown in FIG. 7 (1), the adhesive 7 is applied to the surface of the second substrate 11 having the electrode pads 12, and the first substrate having the solder electrodes 6 is attached to each electrode pad 12 of the second substrate 11. It is opposed to each solder electrode 6 of the first substrate 1 so as to face each other. The first substrate 1 is placed on the second substrate 11 so that the solder electrode 6 is in contact with the electrode pad 12, and the solder electrode 6 is heated and / or crimped to the second substrate 11 via the solder electrode 9 as shown in FIG. 7 (2). , The electrode pad 2 of the first substrate 1 and the electrode pad 12 of the second substrate are connected to form an electrical connection structure. As a result, the laminated body 20 having an electrical connection structure is manufactured. Since the laminate 20 is manufactured through the step (5) of removing the resist 5, unlike the laminate 10, the laminate 20 does not include the resist 5.

In both of the first and second laminated body manufacturing methods, when the step (3) in the solder electrode manufacturing method is performed after the step (2) and before the step (4), copper is used. The electrode pad of the first substrate and the electrode pad of the second substrate form an electrical connection structure via a solder electrode made of metal and solder.

Since the method for manufacturing a laminate of the present invention includes the above-mentioned method for manufacturing a solder electrode, it has the same effect as the above-mentioned method for manufacturing a solder electrode. That is, the method for manufacturing a laminate of the present invention can produce a laminate having an electrical connection structure that fits the shape of the opening of the solder resist and includes a solder electrode suitable for the purpose.

As described above, the laminate manufactured by the method for producing a laminate of the present invention may or may not have a solder resist between the first substrate and the second substrate. If the laminate comprises a solder resist, the solder resist is used as an underfill.
The laminate manufactured by the method for manufacturing a laminate of the present invention can be used for various electronic components such as semiconductor elements, display elements, and power devices.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples. In the description of the following examples and the like, "part" is used to mean "part by mass".
<Measurement method of physical properties>
(Measuring method of weight average molecular weight (Mw) of alkali-soluble resin)
The weight average molecular weight (Mw) of the alkali-soluble resin was measured by the gel permeation chromatography method under the following conditions.
-Column: Tosoh columns TSK-M and TSK2500 are connected in series.-Solvent: Tetrahydrofuran-Temperature: 40 ° C.
-Detection method: Refractive index method-Standard material: Polystyrene-GPC device: Tosoh, device name "HLC-8220-GPC"

<Manufacturing of photosensitive resin composition>
[Synthesis Example 1] Synthesis of alkali-soluble resin (A1) In a flask, 10 g of 2,2'-azobisisobutyronitrile as a polymerization initiator, 200 g of propylene glycol monomethyl ether acetate as a polymerization solvent, and 11 g of methacrylic acid as a monomer. , 4- (1-Methylethenyl) phenol 14 g, N-cyclohexylmaleimide 40 g, and n-butyl acrylate 35 g were added, and the temperature was raised to 80 ° C. with stirring. Then, it heated at 80 degreeC for 3 hours.

After the heating was completed, the reaction product was added dropwise to a large amount of cyclohexane and coagulated. This coagulated product was dissolved in propylene glycol monomethyl ether acetate and then washed with liquid to obtain an alkali-soluble resin (A1).

The weight average molecular weight (Mw) of the alkali-soluble resin (A1) was 10,200. When the content of the structural unit contained in the alkali-soluble resin (A1) was measured by ¹³ C NMR, the structural unit derived from methacrylic acid was 11% by mass and the structural unit derived from 4- (1-methylethenyl) phenol was 14% by mass. , The structural unit derived from N-cyclohexyl maleimide was 40% by mass, and the structural unit derived from n-butyl acrylate was 35% by mass.

[Synthesis Examples 2-9] Alkali-soluble resins (A2) to (A7), (AR1), and (AR2)
) Synthetic Examples 2 to 9 are alkali-soluble resins (A2) having structural units and contents derived from the monomers shown in Table 1 below, in the same manner as in Synthesis Example 1 except that the monomers used are changed. -(A7), (AR1) and (AR2) were synthesized, respectively. The unit of the content of the structural unit derived from the monomer in Table 1 is mass%. The weight average molecular weight (Mw) of each alkali-soluble resin is shown in Table 1.

[Example 1]
<Manufacturing of photosensitive resin composition>
100 parts by mass of alkali-soluble resin (A1), 47 parts by mass of polyfunctional acrylate (trade name "Aronix M8100", manufactured by Toa Synthetic Co., Ltd.), 5 parts by mass of trimethyl propanetriacrylate, 0.4 parts by mass. Photoinitiator (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-yl]-, 1- (O-acetyloxime), trade name "IRGACURE OXE02", BASF 3 parts by mass of 3-glycidoxypropyltrimethoxysilane and 0.1 parts by mass of octamethylcyclotetrasiloxane are uniformly mixed with 80 parts by mass of propylene glycol monomethyl ether acetate, and the pore size is 10 μm. The photosensitive resin composition of Example 1 was produced by filtering with the capsule filter of.

<Measurement of outgas amount of photosensitive resin composition>
The photosensitive resin composition of Example 1 was applied onto a silicon substrate by a spin coating method using a spin coater, and heated on a hot plate at 110 ° C. for 5 minutes to form a coating film having a thickness of 16 μm. Then, using an aligner (manufactured by Sus, model "MA-200"), the entire surface was exposed at an irradiation intensity of 300 mJ / cm ² . After the exposure, the coating film was brought into contact with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 60 seconds, and the coating film was washed with running water and developed. Then, under a nitrogen flow, it was heated in a convection oven at 270 ° C. for 10 minutes. After heating, a silicon substrate was cut into a size of 1 cm × 1 cm to prepare a substrate for measuring the amount of outgas.

The outgas amount is measured when the substrate for outgas amount measurement is heated at 260 ° C. for 15 minutes using a headspace GC-MS (device name "Agient 6890N", manufactured by Agilent Technologies, Inc., flow rate: He2.0 ml / min). The amount of gas generated was measured. The measurement results are shown in Table 2.

<Manufacturing of solder electrodes>
The photosensitive resin composition of Example 1 was applied by a spin coating method on a substrate having a plurality of copper electrode pads on a silicon substrate using a spin coater, and heated on a hot plate at 120 ° C. for 5 minutes. .. Then, using an aligner (manufactured by Sus, model “MA-200”), light having a wavelength of 420 nm was exposed through a pattern mask at an irradiation intensity of 300 mJ / cm ² . After the exposure, the coating film was brought into contact with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 240 seconds, and the coating film was washed with running water and developed. Next, the resist was heated in a convection oven at 200 ° C. for 10 minutes under a nitrogen flow to form a resist-holding substrate holding a solder resist having an opening in a portion corresponding to the electrode pad. When observed with an electron microscope, the opening of each opening was a circle with a diameter of 7 μm, and the depth of each opening was 25 μm.

The resist-holding substrate was immersed in a 1 mass% sulfuric acid aqueous solution at 23 ° C. for 1 minute, washed with water, and dried. A molten solder obtained by melting SAC305 (lead-free solder, product name of Senju Metal Industry Co., Ltd.) at 250 ° C. inside the solder resist opening of the resist holding substrate after drying using an IMS head. The solder electrode was manufactured by filling at 250 ° C. for 10 minutes while heating. The resist holding substrate after filling with molten solder was observed with an optical microscope, and the solder embedding property was evaluated according to the following criteria. The evaluation results are shown in Table 2.
A: The number of openings in the portion not filled with the molten solder was less than 1% of the total number of openings in the resist holding substrate.
B: The number of openings in the portion not filled with the molten solder was 1% or more and less than 10% with respect to the total number of openings in the resist holding substrate.
C: The volume of the portion not filled with the molten solder was 10% or more with respect to the total number of openings of the resist holding substrate.

Similarly, the size of the pattern mask used for exposure was reduced to prepare a resist-holding substrate in which the openings of the openings were circular with a diameter of 5 μm and the depth of each opening was 25 μm. Then, the molten solder was filled in the same manner to manufacture a solder electrode. The solder embedding property at that time was evaluated in the same manner as above. The evaluation results are shown in Table 2.

[Examples 2 to 7, Comparative Example 1 and Comparative Example 2]
<Manufacturing of photosensitive resin composition>
Examples 2 to 7 and the same method as in Example 1 except that the alkali-soluble resins (A2) to (A7), (AR1) and (AR2) were used instead of the alkali-soluble resin (A1), respectively. The photosensitive resin compositions of Comparative Example 1 and Comparative Example 2 were produced.

<Measurement of outgas amount of photosensitive resin composition>
The amount of outgas was measured in the same manner as in Example 1 except that the photosensitive resin compositions of Examples 2 to 7, Comparative Example 1 and Comparative Example 2 were used instead of the photosensitive resin composition of Example 1. rice field. The measurement results are shown in Table 2.

<Manufacturing of solder electrodes>
Solder electrodes were produced in the same manner as in Example 1 except that the photosensitive resin compositions of Examples 2 to 7, Comparative Example 1 and Comparative Example 2 were used instead of the photosensitive resin composition of Example 1. The solder embedding property was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

1, 11 Substrate 2, 12 Electrode pad 3 Coating 4 Opening 5 Resist 6 Solder electrode 7 Adhesive 8 IMS head 9 Molten solder 10, 20 Laminate 13 Adhesive layer 15 Plating film

Claims (1)

An alkali-soluble resin having a structural unit (a1) represented by the following formula (a1) of 15 to 60% by mass, a structural unit represented by the following formula (a2) of 15 to 50% by mass, and a structural unit represented by the following formula (a3). (A) (However, the alkali-soluble resin (A) does not have a structural unit derived from a polycyclic condensed ring aliphatic (meth) acrylate) and has at least one ethylenically unsaturated double bond in one molecule. A photosensitive resin composition containing the compound (B) and the photoradical polymerization initiator (C).

(In formula (a1), R ¹ represents an alkyl group which may independently have a hydrogen atom or a substituent having 1 to 10 carbon atoms; R ² may have a substituent and which may have a substituent. Group, phenyl group, naphthyl group, benzyl group.)

(In formula (a2), R ³ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ⁴ represents at least one hydrogen atom of the alkyl group as a hydroxyl group or a hydroxyl group. Indicates a group substituted with an alkoxy group.)

(In formula (a3), R ⁵ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 10 carbon atoms; R ⁶ is a single bond, -OCO-, -COO-, -CONH. -Or -O-; R ⁷ indicates an aryl group having a phenolic hydroxyl group.)

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