JP4765974B2 - Negative radiation sensitive resin composition - Google Patents

Description

  The present invention relates to a negative-type radiation-sensitive resin composition suitable for producing a plated model, a transfer film using the composition, and a method for producing a plated model.

  In recent years, with the downsizing of electronic devices such as mobile phones, large-scale integrated circuits (LSIs) have been rapidly integrated and multi-layered. For this reason, a multi-pin mounting method on a substrate for mounting an LSI on an electronic device is required, and bare chip mounting using a tape automated bonding (TAB) method or a flip chip method has attracted attention. In such a multi-pin mounting method, it is necessary that protruding electrodes called bumps, which are connection terminals, be arranged on the LSI chip with high accuracy.

  In order to obtain various precision parts such as bumps, precision microfabrication technology is required, but at present, the mainstream of this technology is photo application. Photo application is the application of a radiation-sensitive resin composition to the surface of a workpiece, forming a film, patterning the coating film by photolithography, and using this as a mask for electroetching mainly chemical etching, electrolytic etching or electroplating. It is a general term for technologies for manufacturing various precision parts by forming technology alone or in combination.

  More specifically, the bump is currently processed in the following procedure. First, a barrier metal serving as a conductive layer is laminated on a wafer on which an LSI element is processed, and then a radiation-sensitive resin composition so-called resist is applied and dried. Next, radiation is irradiated through a mask (hereinafter referred to as “exposure”) so that a portion where a bump is to be formed is opened, and then development is performed to form a pattern. Thereafter, an electrode material such as gold or copper is deposited by electrolytic plating using this pattern as a mold. Next, after peeling off the resin portion, the barrier metal is removed by etching. Thereafter, the chip is cut out from the wafer into a square, and the process proceeds to a packaging process such as packaging of TAB or a flip chip.

There are various bump shapes such as ball bumps, mushroom bumps, and straight bumps.
The present inventors have already proposed a radiation-sensitive resin composition that can be suitably used for photo applications (see Patent Document 1). If this composition is used, a highly accurate bump can be formed on a substrate of copper, gold or the like.

In the series of bump processing steps described above, the following characteristics are required for the resist.
(1) A coating film having a uniform thickness can be formed.
(2) The side wall of the pattern serving as a mold is nearly vertical, and the pattern is faithful to the mask dimensions.
(3) High sensitivity and excellent developability in order to increase the production efficiency of the process.
(4) It has good wettability with respect to the plating solution.
(5) The resist component does not elute into the plating solution during plating and does not deteriorate the plating solution.
(6) High adhesion to the substrate so that the plating solution does not ooze out to the interface between the substrate and the resist during plating.
(7) After plating, it should be easily peeled off with a stripping solution.

The present inventors have already proposed a radiation-sensitive resin composition that is suitable for the formation of such bumps and has high adhesion to a gold substrate (see Patent Document 2).
In recent years, with downsizing of LSIs, there is a need for bumps with small height variations even at narrow pitches. To form such bumps, low current density and long-time plating at narrow pitches are required. It is said that processing is necessary. However, when bumps are formed by forming a resin film from the above composition, the resist pattern swells when immersed in the plating solution for a long time, and the plating solution oozes out at the interface between the pattern and the substrate. However, there is a problem in that the resolution is poor.

On the other hand, Patent Document 3 discloses a linear polymer compound obtained by copolymerizing phenoxypolyethylene glycol (meth) acrylate, benzyl (meth) acrylate, a carboxyl group-containing vinyl monomer and another vinyl monomer. , An unsaturated linear polymer compound to which glycidyl (meth) acrylate is added, an acid anhydride-modified epoxy acrylate compound, a photopolymerizable compound containing two or more terminal ethylene groups, and a photoinitiator Is disclosed. However, Patent Document 3 does not disclose or suggest hydroxystyrene, nor does it suggest the effect.
JP 2000-39709 A JP-A-10-161307 JP-A-5-341521

  The present invention is a manufacturing method in which the swelling of a resist with respect to a plating solution is small, the bleeding of the plating solution to the interface between a pattern and a substrate is suppressed, and a thick plated model such as a bump or a wiring can be accurately formed. It is an object of the present invention to provide a method, a negative radiation-sensitive resin composition exhibiting a sensitivity suitable for the production method and excellent in resolution, heat resistance, and the like, and a transfer film using the composition.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that (A) a polymer containing a structural unit derived from a monomer having a specific structure, and (B) at least one When using a negative radiation-sensitive resin composition comprising a compound having an ethylenically unsaturated double bond, and (C) a radiation-sensitive radical polymerization initiator, and a transfer film comprising the composition, The present inventors have found that high bumps can be formed with high accuracy and have completed the present invention.

That is, the negative radiation sensitive resin composition according to the present invention is
(A) a polymer containing a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2);
(B) It contains at least one compound having an ethylenically unsaturated double bond, and (C) a radiation-sensitive radical polymerization initiator.

式（１）中、Ｒ¹は水素原子またはメチル基を表し、Ｒ²は炭素数６〜１２の直鎖状、環状もしくは芳香族の炭化水素基、またはこれらの基の少なくとも１つの水素原子が炭化水素基に置換された置換炭化水素基を表し、Ｒ⁴は−（Ｃ_nＨ_2n）−基を表わし、ｍは１〜１０の整数であり、ｎは２〜４の整数である。

In the formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear, cyclic or aromatic hydrocarbon group having 6 to 12 carbon atoms, or at least one hydrogen atom of these groups It represents a substituted substituted hydrocarbon group in the hydrocarbon group, R ⁴ is - (C _n H _2n) - represents a group, m is an integer of 1 to 10, n represents an integer of 2 to 4.

式（２）中、Ｒ³は水素原子またはメチル基を表す。

In formula (2), R ³ represents a hydrogen atom or a methyl group.

  The radiation-sensitive radical polymerization initiator (C) preferably contains a biimidazole compound represented by the following formula (3).

式（３）中、Ｘはそれぞれ独立に水素原子、メチル基または塩素原子を表し、Ｐｈはフェニル基を表す。

In formula (3), X represents a hydrogen atom, a methyl group, or a chlorine atom each independently, and Ph represents a phenyl group.

  The negative radiation-sensitive resin composition is preferably a negative radiation-sensitive resin composition for producing a plated model, and particularly preferably a negative radiation-sensitive resin composition for producing bumps.

  The negative radiation sensitive resin composition preferably contains 30 to 80 parts by weight of the compound (B) with respect to 100 parts by weight of the polymer (A). Moreover, it is also preferable that 1-40 weight part of said radiation sensitive radical polymerization initiators (C) is contained. Furthermore, it is also preferable that an organic solvent (D) is included.

The transfer film according to the present invention has a support film and a resin film formed on the support film from the negative radiation-sensitive resin composition.
The method for producing a plated model according to the present invention is as follows.
(1) A step of forming a resin film formed from the negative radiation-sensitive resin composition described above on a wafer having a barrier metal layer,
(2) A step of developing the pattern after exposing the resin film,
(3) including a step of depositing an electrode material by electrolytic plating using the pattern as a mold, and (4) a step of removing the barrier metal by etching after peeling off the remaining resin film.

  The radiation-sensitive resin composition of the present invention has good resolution, adhesion, and excellent heat resistance, so that it can be patterned in a good shape on the substrate. Since the curability can be further improved by applying the step, the bump can be formed on the chip substrate with high accuracy and easily. Furthermore, even if immersed in a plating solution for a long time, the resist pattern does not swell, a long-time plating process is possible, and bumps with little height variation can be formed. Thereby, it is possible to cope with the miniaturization of the bump accompanying the downsizing of the LSI.

Hereinafter, the present invention will be specifically described.
The negative radiation-sensitive resin composition according to the present invention comprises (A) a polymer containing a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2), (B) at least A compound having one ethylenically unsaturated double bond and (C) a radiation-sensitive radical polymerization initiator are contained.

式（１）中、Ｒ¹は水素原子またはメチル基を表し、Ｒ²は炭素数６〜１２の直鎖状、環状もしくは芳香族の炭化水素基、またはこれらの基の少なくとも１つの水素原子が炭化水素基に置換された置換炭化水素基を表し、Ｒ⁴は−（Ｃ_nＨ_2n）−基を表わし、ｍは１〜１０の整数であり、ｎは２〜４の整数である。

In the formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear, cyclic or aromatic hydrocarbon group having 6 to 12 carbon atoms, or at least one hydrogen atom of these groups It represents a substituted substituted hydrocarbon group in the hydrocarbon group, R ⁴ is - (C _n H _2n) - represents a group, m is an integer of 1 to 10, n represents an integer of 2 to 4.

式（２）中、Ｒ³は水素原子またはメチル基を表す。

In formula (2), R ³ represents a hydrogen atom or a methyl group.

First, each component will be described.
<Polymer (A)>
The polymer (A) used in the present invention is a polymer containing a structural unit represented by the above formula (1) and a structural unit represented by the above formula (2).

  When the polymer (A) contains the structural unit represented by the above formula (1), the adhesion of the resist to the substrate is enhanced even during plating. There is an effect to prevent the oozing out to the interface.

  The total of the structural units represented by the above formula (1) in the polymer (A) is usually 1 to 40% by weight, and preferably 10 to 30% by weight. When the total of the structural units represented by the above formula (1) in the polymer (A) is within the above range, the molecular weight of the resulting polymer (A) can be sufficiently increased and obtained. Swelling of the radiation sensitive resin film due to the plating solution can be suppressed.

≪Monomer (1 ') ≫
The structure of the above formula (1) can be obtained, for example, by polymerizing the polymer (A) using the monomer (1 ′) represented by the following formula.

式（１’）中、Ｒ¹、Ｒ²、ｍおよびｎは、それぞれ上記式（１）におけるＲ¹、Ｒ²、ｍおよびｎと同義である。

Wherein (1 '), R ^1, R ^2, m and n are respectively the same as R ^1, R ^2, m and n in the formula (1).

As said C6-C12 linear hydrocarbon group, a hexyl group, a heptyl group, an octyl group, a nonyl group etc. are mentioned, for example.
Examples of the cyclic hydrocarbon group having 6 to 12 carbon atoms include cycloalkyl groups such as a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group; adamantane, bicyclo [2.2.1] heptane, and tetracyclo [6.2. 1.1 ^3,6 . And groups derived from bridged hydrocarbons such as 0 ^2,7 ] dodecane and tricyclo [5.2.1.0 ^2,6 ] decane.

  Examples of the aromatic hydrocarbon group having 6 to 12 carbon atoms include phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 4-t-butylphenyl group, 1-naphthyl group, and benzyl group. Etc.

  In the linear hydrocarbon group, cyclic hydrocarbon group and aromatic hydrocarbon group, at least one hydrogen atom may be substituted with a hydrocarbon group such as a methyl group or an ethyl group.

  Examples of the monomer (1 ′) include phenoxydiethylene glycol (meth) acrylate, phenoxytriethylene glycol (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, phenoxydipropylene glycol (meth) acrylate, phenoxytripropylene glycol ( (Meth) acrylate, phenoxytetrapropylene glycol (meth) acrylate, lauroxydiethylene glycol (meth) acrylate, lauroxytriethylene glycol (meth) acrylate, lauroxytetraethylene glycol (meth) acrylate, lauroxydipropylene glycol (meth) acrylate, Lauroxytripropylene glycol (meth) acrylate, Lauroxytetrapropylene glycol Meth) acrylate.

  Among these monomers (1 ′), phenoxydiethylene glycol (meth) acrylate, phenoxytri, and the like are obtained in that a radiation-sensitive resin composition having excellent adhesion to a substrate, heat resistance, and long-term plating treatment resistance can be obtained. Ethylene glycol (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, phenoxydipropylene glycol (meth) acrylate, phenoxytripropylene glycol (meth) acrylate, phenoxytetrapropylene glycol (meth) acrylate are preferred, phenoxydiethylene glycol acrylate, phenoxy Triethylene glycol acrylate and phenoxytetraethylene glycol acrylate are more preferable.

A monomer (1 ') can be used individually or in mixture of 2 or more types.
Further, since the polymer (A) contains the structural unit represented by the above formula (2), swelling of the resist at the time of plating is suppressed, and as a result, the resist does not float or peel off, and for a long time. This has the effect of further preventing the plating solution from seeping out to the interface between the substrate and the resist during plating. In addition, the crosslink density of the cured film can be suppressed, and there is an effect of improving the resolution.

  The total of the structural units represented by the above formula (2) in the polymer (A) is usually 1 to 30% by weight, preferably 10 to 20% by weight. When the total of the structural units represented by the above formula (2) in the polymer (A) is within the above range, the molecular weight of the resulting polymer (A) can be sufficiently increased and obtained. Swelling of the radiation sensitive resin film due to the plating solution can be suppressed.

≪Monomer (2 ′) ≫
The structure of the above formula (2) is, for example, a hydroxyl group-containing aromatic vinyl compound such as o-hydroxystyrene, p-hydroxystyrene, m-hydroxystyrene, p-isopropenylphenol (hereinafter referred to as “monomer (2 ′)”). Can be obtained by polymerizing the polymer (A).

Among these monomers (2 ′), p-hydroxystyrene and p-isopropenylphenol are preferable, and p-isopropenylphenol is preferable in that a radiation-sensitive resin composition excellent in long-term plating treatment resistance can be obtained. Is more preferable.

A monomer (2 ') can be used individually or in mixture of 2 or more types.
≪Monomer (I) ≫
The polymer (A) is further derived from other monomers copolymerizable with the monomers (1 ′) and (2 ′) (hereinafter referred to as “monomer (I)”). Units can be included.

As the monomer (I),
Aromatic vinyl compounds such as styrene, α-methylstyrene, p-methylstyrene, p-methoxystyrene;
Heteroatom-containing alicyclic vinyl compounds such as N-vinylpyrrolidone and N-vinylcaprolactam;
Cyano group-containing vinyl compounds such as acrylonitrile and methacrylonitrile;
1. conjugated diolefins such as 3-butadiene and isoprene;
Carboxyl group-containing vinyl compounds such as acrylic acid and methacrylic acid;
Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono ( (Meth) acrylate, polypropylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) (Meth) acrylic acid esters such as acrylate;
p-hydroxyphenyl (meth) acrylamide etc. are mentioned.

  Among these monomers (I), styrene, acrylic acid, methacrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, tricyclodecanyl (meth) acrylate, benzyl ( Preferred are meth) acrylate, isobornyl (meth) acrylate, p-hydroxyphenyl (meth) acrylamide and the like.

Monomers (I) can be used alone or in admixture of two or more.
Polymerization of the polymer (A) can be performed, for example, by radical polymerization. Examples of the polymerization method include an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, and a bulk polymerization method, and the solution polymerization method is particularly preferable.

≪Polymerization initiator≫
As a polymerization initiator used when producing the polymer (A), a normal radical polymerization initiator can be used.

Such polymerization initiators include 2,2′-azobisisobutyronitrile, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobis- (4-methoxy-). 2,4-dimethylvaleronitrile), 2,2′-azobis- (2-methylbutyronitrile), 1,1′-azobis- (cyclohexane-1-carbonitrile), dimethyl-2,2′-azobis ( Azo compounds such as 2-methylpropionate);
Examples thereof include organic peroxides such as benzoyl peroxide, lauroyl peroxide, tert-butylperoxypivalate, 1,1′-bis- (tert-butylperoxy) cyclohexane, hydrogen peroxide, and the like. Moreover, when using the said organic peroxide for a radical polymerization initiator, it is good also as a redox type initiator combining a reducing agent.

≪Polymerization solvent≫
In addition, the polymerization solvent used when the polymer (A) is produced by the solution polymerization method is not particularly limited as long as it does not react with the monomer component used and dissolves the polymer to be produced. Not a thing.

Examples of such a polymerization solvent include alcohols such as methanol, ethanol, ethylene glycol, diethylene glycol, and propylene glycol;
Cyclic ethers such as tetrahydrofuran and dioxane;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl Alkyl ethers of polyhydric alcohols such as ethers;
Alkyl ether acetates of polyhydric alcohols such as ethylene glycol monoethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol ethyl ether acetate and propylene glycol monomethyl 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, diacetone alcohol;
Ethyl acetate, butyl acetate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-3-methylbutane Examples include esters such as methyl acid, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, and ethyl lactate.

Of these, cyclic ethers, polyhydric alcohol alkyl ethers, polyhydric alcohol alkyl ether acetates, ketones, and esters are preferred.
The weight average molecular weight (Mw) of the polymer (A) obtained by the above radical copolymerization is measured by gel permeation chromatography, and is usually 1,000 to 100,000, preferably 2,000 to 100,000 in terms of polystyrene. It is in the range of 50,000, more preferably 3,000 to 20,000.

<(B) Compound having at least one ethylenically unsaturated double bond>
The compound (B) used in the present invention is a liquid or solid compound at room temperature having at least one ethylenically unsaturated group in the molecule. As the compound (B), a (meth) acrylate compound having a (meth) acryloyl group or a compound having a vinyl group is preferably used. The (meth) acrylate compound is classified into a monofunctional compound and a polyfunctional compound, and any compound can be used.

Examples of the monofunctional (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, methyl (meth) acrylate, and 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 Rate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl amyl (meth) acrylate, lauryl (meth) acrylate, octadecyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl ( (Meth) acrylate, ethoxydiethylene glycol (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, phenoxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol ( (Meth) acrylate, ethoxyethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate Over DOO, phenoxy polyethylene glycol (meth) acrylate, phenoxy polypropylene glycol (meth) acrylate, methoxy polypropylene 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, diacetone (meth) acrylamide, isobutoxymethyl (meth) acrylamide, N-vinylpyrrolidone, N-vinylcaprolactam, N, N-dimethyl (meth) acrylamide, tert- Octyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 7-amino-3,7-dimethyloctyl (meth) acrylate, dimethyl maleate, diethyl maleate, dimethyl fumarate, fumaric acid Diethyl, ethylene glycol monomethyl ether (meth) acrylate, ethylene glycol monoethyl ether (meth) acrylate, glycerol (meth) acrylate, acrylic acid , Methacrylamide, and the like (meth) acrylonitrile.

  Examples of the polyfunctional (meth) acrylate compound include trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4- Butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di ( (Meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, tricyclodecane dimethyl Nord di (meth) acrylate, epoxy (meth) acrylate obtained by adding (meth) acrylic acid to diglycidyl ether of bisphenol A, bisphenol A di (meth) acryloyloxyethyl ether, bisphenol A di (meth) acryloyloxyethyloxyethyl Ether, bisphenol A di (meth) acryloyloxymethyl ethyl ether, tetramethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipenta Examples include erythritol hexa (meth) acrylate.

Moreover, as the ethylenically unsaturated compound (B), a commercially available compound can be used as it is. As commercially available compounds, Aronix M-210, M-309, M-310, M-400, M-7100, M-8030, M-8060, M-8100, M-8100, M -9050, M-240, M-245, M-6100, M-6200, M-6200, M-6250, M-6300, M-6400, M-6500 (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 (manufactured by Nippon Kayaku Co., Ltd.), Biscote # 295, 300, 260, 312, 335HP, 360, GPT 3PA, 400 (above, manufactured by Osaka Organic Chemical Industry Co., Ltd.).

Compound (B) may be used alone or in combination of two or more.
The usage-amount of a compound (B) is 30-80 weight part normally with respect to 100 weight part of polymers (A) which have alkali solubility, Preferably it is 40-70 weight part. When the amount of the compound (B) is within the above range, the resulting radiation-sensitive resin film has good sensitivity at the time of exposure, is excellent in compatibility with the polymer (A), and preserves the coating liquid. Stability is improved.

<(C) Radiation sensitive radical polymerization initiator>
The radiation-sensitive radical polymerization initiator (C) used in the present invention is one that generates radicals upon irradiation with radiation and initiates radical polymerization of the ethylenically unsaturated compound (B).

  Here, the radiation means ultraviolet rays, visible rays, far ultraviolet rays, X-rays, electron beams, and the like. Normally, a mercury lamp is used as a curing radiation source for the radiation sensitive resin. When curing the radiation sensitive resin, it is common to use i-line having a wavelength of 365 nm and h-line having a wavelength of 405 nm in the emission spectrum of the mercury lamp.

  Among these, i-line is high energy, has high curability and is not easily inhibited by oxygen, but is easily absorbed because of its short wavelength. Therefore, when i-line is used for curing a thick radiation-sensitive resin film, sufficient energy cannot reach the bottom of the radiation-sensitive resin film, and a desired pattern is not formed on the resin film. There is. For example, the cross-sectional shape of the radiation-sensitive resin film after patterning may not be rectangular, or it may be a trapezoid with a bottom that is more than the surface layer of the radiation-sensitive resin film.

  On the other hand, since the h line has lower energy than the i line, it takes time to cure. Therefore, since the surface of the radiation sensitive resin film is easily inhibited by oxygen, the residual film ratio after patterning may be significantly reduced. However, since the h-line has a longer wavelength than the i-line, the light transmittance is high. Therefore, even when it is used for a thick film of radiation sensitive resin, energy easily reaches the bottom of the radiation sensitive resin film, so that the shape of the cross section of the radiation sensitive resin film after patterning becomes rectangular, and the above resin film Thus, a desired pattern is easily formed.

Since i-line and h-line have the characteristics as described above, in order to obtain a desired high-accuracy pattern in which not only the surface layer part of the radiation-sensitive resin film but also the bottom part is sufficiently cured, the present invention is applied. Such a radiation sensitive resin composition preferably satisfies the following requirements. When a resin film having a dry film thickness of 70 μm was formed from the composition,
(1) The transmittance of i-line (365 nm radiation) of the resin film is preferably 10% or more, more preferably 12-30%, and (2) h-line (405 nm radiation) of the resin film The transmittance is preferably 60% or more, more preferably 65 to 80%.

  If a composition having such characteristics is used, a radiation sensitive resin film having a film thickness of 5 to 200 μm is formed on the chip base material, and the radiation sensitive resin is irradiated with i rays and h rays. A desired highly accurate pattern in which not only the surface layer portion of the film but also the bottom portion is sufficiently cured can be obtained.

That is, by improving the transmittance of both wavelengths, the attenuation of light transmitted from the surface of the radiation-sensitive resin film to the inside is suppressed, and the cross-section of the patterning portion is cured by uniformly curing the entire radiation-sensitive resin film. In this case, a cured film can be obtained in which the bottom and side walls are substantially perpendicular. This makes it possible to form straight high bumps with high accuracy.

The measurement of the transmittance of radiation can be performed, for example, by the following method.
First, lactic acid having a composition containing (A) the polymer, (B) a compound having at least one ethylenically unsaturated double bond, and (C) a radiation-sensitive radical polymerization initiator in a predetermined amount. An ethyl solution (65% by weight) is prepared, a resin film is formed on a quartz substrate having a thickness of 1 mm by spin coating, and then baked on a hot plate at 120 ° C. for 5 minutes to remove the solvent. A coating film is formed. In this case, the number of rotations during spin coating is controlled in advance so that the film thickness of the coating film after baking is 70 μm.

  The transmittance of the resin film formed on the quartz substrate in this manner is measured using a spectrophotometer (for example, HITACHI Spectrophotometer U-2010) at a wavelength of 300 nm to 500 nm using a quartz substrate without the resin film as a reference. To do.

In addition, when the absorbance is converted into an extinction coefficient, the resin composition according to the present invention forms an uncured resin film having a dry film thickness of 70 μm.
It is preferable that the composition has (1) an extinction coefficient of 15000 m ⁻¹ or less for 365 nm radiation and (2) an extinction coefficient of 4000 m ⁻¹ or less for 405 nm radiation.

The extinction coefficient ε can be obtained by applying the measured transmittance to the formula ε = log (I ₀ / I) / L (where ε is the extinction coefficient (m ⁻¹ ) and I is transmitted through the resin film). The light intensity (cd) immediately after exposure, I ₀ is the light intensity (cd) before passing through the resin film, and L is the dry film thickness (m) of the resin film.

  As a method for preparing a resin composition having such a preferable extinction coefficient, there is a method of adding the kind and amount of the radiation sensitive radical polymerization initiator (C) so as to obtain a resin composition having a preferable extinction coefficient. . The addition amount of the radiation sensitive radical polymerization initiator (C) is usually 1 to 40 parts by weight, preferably 5 to 30 parts by weight, more preferably 100 parts by weight of the polymer (A). 10 to 20 parts by weight.

  Examples of such a radiation sensitive radical polymerization initiator (C) include a biimidazole compound represented by the following formula (3).

式（３）中、Ｘはそれぞれ独立に水素原子、メチル基または塩素原子を表し、Ｐｈはフェニル基を表す。

In formula (3), X represents a hydrogen atom, a methyl group, or a chlorine atom each independently, and Ph represents a phenyl group.

  Examples of the biimidazole compound include 2,2′-bis (2,4-dichlorophenyl) -4,5,4 ′, 5′-tetraphenyl-1,2′-biimidazole, 2,2′-bis (2 -Chlorophenyl) -4,5,4 ', 5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis (2,4-dichlorophenyl) -4,5,4', 5'-tetra Phenyl-1,2′-biimidazole, 2,2′-bis (2,4-dimethylphenyl) -4,5,4 ′, 5′-tetraphenyl-1,2′-biimidazole, 2,2 ′ -Bis (2-methylphenyl) -4,5,4 ', 5'-tetraphenyl-1,2'-biimidazole, 2,2'-diphenyl-4,5,4', 5'-tetraphenyl- 1, 2'-biimidazole and the like. These compounds can be used alone or in combination of two or more.

  The addition amount of the biimidazole compound is usually 1 to 30 parts by weight, preferably 1 to 20 parts by weight, and more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the polymer (A). . When the addition amount of the biimidazole compound is within the above range, the resulting radiation-sensitive resin film has good sensitivity at the time of exposure, and radiation passes through the inside of the resin film. Can be formed.

  In the present invention, the radiation-sensitive radical polymerization initiator (C) can be used in combination with the biimidazole compound and other radiation-induced radical polymerization initiators. Other radiation radical polymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, 4,4′-bis (diethylamino) benzophenone, 2-benzyl-2-dimethylamino-1- And (4-morpholinophenyl) -butanone-1, 2-methyl-1- [4- (methylthio) phenyl] -2-monforinopropanone-1. Examples of commercially available products include Irgacure 369 (manufactured by Ciba Specialty Chemicals), Irgacure 907 (manufactured by Ciba Specialty Chemicals), and the like. These compounds can be used alone or in combination of two or more.

<Organic solvent (D)>
The resin composition of the present invention may contain an organic solvent as necessary. As the organic solvent (D), those capable of uniformly dissolving the polymer (A) and each component and not reacting with each component are used. As such an organic solvent, the solvent similar to the polymerization solvent used when manufacturing a polymer (A) can be used. Also, N-methylformamide, N, N-dimethylformamide, N-methylformanilide, N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, benzylethyl ether, dihexyl ether, acetonylacetone , Isophorone, caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate, phenyl cellosolve acetate, etc. High boiling solvents can also be used.

Among these, alkyl ethers of polyhydric alcohols such as ethylene glycol monoethyl ether and diethylene glycol monomethyl ether in terms of solubility, reactivity with each component, and ease of resin film formation;
Alkyl ether acetates of polyhydric alcohols such as ethylene glycol monoethyl ether acetate and propylene glycol monomethyl ether acetate;
Esters such as ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, ethyl 2-hydroxypropionate, ethyl lactate;
Ketones such as diacetone alcohol are preferred.

The said solvent can be used individually or in mixture of 2 or more types. Moreover, the usage-amount of a solvent can be suitably determined according to a use, a coating method, etc.
<Other ingredients>
In addition to the negative radiation sensitive resin composition according to the present invention, a thermal polymerization inhibitor, a surfactant, an adhesion aid, and other additives can be used as necessary.

≪Thermal polymerization inhibitor≫
Moreover, the radiation sensitive resin composition of this invention can be made to contain a thermal-polymerization inhibitor. Examples of such thermal polymerization inhibitors include pyrogallol, benzoquinone, hydroquinone, methylene blue, tert-butylcatechol, monobenzyl ether, methylhydroquinone, amylquinone, amyloxyhydroquinone, n-butylphenol, phenol, hydroquinone monopropyl ether, 4,4. '-(1-methylethylidene) bis (2-methylphenol), 4,4'-(1-methylethylidene) bis (2,6-dimethylphenol), 4,4 '-[1- [4- (1 -(4-hydroxyphenyl) -1-methylethyl) phenyl] ethylidene] bisphenol, 4,4 ', 4 "-ethylidenetris (2-methylphenol), 4,4', 4" -ethylidenetrisphenol, 1, 1,3-tris (2,5-dimethyl-4-hydroxypheny ) -3-phenyl-propane and the like. The amount of these compounds used is preferably 5 parts by weight or less with respect to 100 parts by weight of the polymer (A).

≪Surfactant≫
In addition, the radiation-sensitive resin composition according to the present invention may contain a surfactant for the purpose of improving coating properties, antifoaming properties, leveling properties and the like.

As the surfactant, a commercially available compound can be used as it is. Specific examples of commercially available surfactants include, for example, FTX-204D, FTX-208D, FTX-212D, FTX-216D, FTX-218, FTX-220D, FTX-222D (manufactured by Neos Co., Ltd.) , BM-1000, BM-1100 (above, manufactured by BM Chemie), MegaFuck F142D, F172, F173, F183 (above, manufactured by Dainippon Ink and Chemicals), Florard FC-135, FC -170C, FC-430, FC-431 (above, manufactured by Sumitomo 3M), Surflon S-112, S-113, S-131, S-141, S-145 (above, Asahi Glass Co., Ltd.), SH-28PA, -190, -193, SZ-6032, SF-8428 (above, Toray Dow Corning Silicone) Co., Ltd.)), and the like. Among these, FTX-216D, FTX-218, and FTX-220D are preferable.

The amount of these surfactants used is preferably 5 parts by weight or less with respect to 100 parts by weight of the polymer (A).
≪Adhesion aid≫
In the radiation sensitive resin film of the present invention, an adhesion assistant can be used to improve the adhesion to the chip substrate. As the adhesion assistant, a functional silane coupling agent is preferable.

  Here, the functional silane coupling agent means a silane coupling agent having a reactive substituent such as a carboxyl group, a methacryloyl group, an isocyanate group, or an epoxy group.

Examples of this functional silane coupling agent include trimethoxysilylbenzoic acid, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, and γ-glycidoxypropyl. Examples include trimethoxysilane and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.

The amount used is preferably 20 parts by weight or less with respect to 100 parts by weight of the polymer (A).
≪Other additives≫
In addition, when forming the radiation sensitive resin film of the present invention, in order to finely adjust the solubility in an alkali developer,
Monocarboxylic acids such as acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid, iso-valeric acid, benzoic acid, cinnamic acid;
Lactic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 2-hydroxycinnamic acid, 3-hydroxycinnamic acid, 4-hydroxycinnamic acid, 5-hydroxy Hydroxymonocarboxylic acids such as isophthalic acid, syringic acid;
Oxalic acid, succinic acid, glutaric acid, adipic acid, maleic acid, itaconic acid, hexahydrophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, Polyvalent carboxylic acids such as trimellitic acid, pyromellitic acid, cyclopentanetetracarboxylic acid, butanetetracarboxylic acid, 1,2,5,8-naphthalenetetracarboxylic acid;
Itaconic anhydride, succinic anhydride, citraconic anhydride, dodecenyl succinic anhydride, tricarbanilic anhydride, maleic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hymic anhydride, 1,2,3,4-butanetetra Acid anhydrides such as carboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitic anhydride, glycerin tris anhydrous trimellitate ;
Can also be added to the coating solution.

Furthermore, the radiation sensitive resin film of the present invention may contain a filler, a colorant, a viscosity modifier and the like as necessary.
Examples of the filler include silica, alumina, talc, bentonite, zirconium silicate, and powdered glass. Colorants include alumina white, clay, barium carbonate, barium sulfate and other extender pigments; zinc white, lead white, yellow lead, red lead, ultramarine, bitumen, titanium oxide, zinc chromate, bengara, carbon black, etc. Pigments; organic pigments such as brilliant carmine 6B, permanent red 6B, permanent red R, benzidine yellow, phthalocyanine blue, and phthalocyanine green; basic dyes such as magenta and rhodamine; direct dyes such as direct scarlet and direct orange; Examples include acid dyes such as yellow.

Examples of the viscosity modifier include bentonite, silica gel, and aluminum powder.
The use amount of these additives may be within the range not impairing the object of the present invention, and preferably 50 when the total amount of the components (A), (B), and (C) is 100% by weight. % By weight or less.

  The radiation-sensitive resin composition in the present invention can improve the wettability of the resin film with respect to the developer, and can further improve the wettability with respect to the plating solution in the plating step. Therefore, it is possible not only to form a thick-film plated object such as a bump or wiring, but also to improve plating defects in the plating process. For example, plating such as a bump or wiring of an integrated circuit element It is suitably used for manufacturing a shaped article. Furthermore, since the plating process can be performed for a long time, bumps with little height variation can be formed. Thereby, it is possible to cope with the miniaturization of the bump accompanying the downsizing of the LSI.

The method for producing a plated model according to the present invention is as follows.
(1) A step of forming a resin film made of the above negative radiation sensitive resin composition on a wafer having a barrier metal layer,
(2) A step of developing the pattern after exposing the resin film,
(3) including a step of depositing an electrode material by electrolytic plating using the pattern as a mold, and (4) a step of removing the barrier metal by etching after peeling off the remaining resin film.

  The resin film formed in the step (1) can be obtained by applying the resin composition according to the present invention on a wafer and drying it. It can also be obtained by transferring a resin film from a transfer film onto a wafer using a transfer film according to the present invention described later.

  The transfer film according to the present invention has a support film and a resin film made of the negative radiation-sensitive resin composition on the support film. Such a transfer film can be produced by applying the negative radiation sensitive resin composition on a support film and drying it. Examples of the method for applying the composition include spin coating, roll coating, screen printing, and applicator methods. Further, the material of the support film is not particularly limited as long as it has a strength that can withstand the production and use of the transfer film.

In the transfer film, the resin film preferably has a thickness of 5 to 200 μm.
The transfer film according to the present invention can peel a support film to form a negative radiation sensitive resin film. The said resin film can be used for manufacture of a plating molded article similarly to the composition which concerns on this invention.

  The alkali developer used for developing the exposed resin film in step (2) is a solution obtained by dissolving one or more alkaline compounds in water or the like. In addition, after the development process with an alkali developer is performed, a washing process is usually performed.

〔Example〕
EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.

[Synthesis Example 1]
<Synthesis of Polymer A1>
In a flask equipped with a nitrogen-substituted dry ice / methanol reflux apparatus, 5.0 g of 2,2′-azobisisobutyronitrile and 150 g of ethyl lactate were charged and stirred until the polymerization initiator was dissolved. To this solution, methacrylic acid (10 g), p-isopropenylphenol (15 g), isobornyl acrylate (40 g), n-butyl acrylate (5 g), tricyclo (5.2.1.0 ^2,6 ) decanyl Methacrylate (15 g) and phenoxytripropylene glycol acrylate (15 g) were charged, stirring was started gently, and the temperature was raised to 80 ° C. Thereafter, polymerization was carried out at 80 ° C. for 6 hours.

[Synthesis Examples 2 to 14]
<Synthesis of Polymers A2 to A9 and Comparative Examples CA1 to CA4>
Polymers A2 to A9 and CA1 to CA4 were synthesized in the same manner as the synthesis of the polymer A1 of Synthesis Example 1 except that the types and amounts of the compounds were changed according to the composition of Table 1 below.

<Synthesis of Polymer A10>
In a flask equipped with a nitrogen-substituted dry ice / methanol refluxer, 5.0 g of 2,2′-azobisisobutyronitrile and 150 g of propylene glycol monomethyl ether acetate (PGMEA) are charged until the polymerization initiator is dissolved. Stir. To this solution was added methacrylic acid (10 g), p-isopropenylphenol (15 g), isobornyl acrylate (40 g), n-butyl acrylate (5 g), tricyclo (5.2.1.0 ^2,6
) Decanyl methacrylate (15 g) and phenoxytripropylene glycol acrylate (15 g) were charged, stirring was started gently, and the temperature was raised to 80 ° C. Thereafter, polymerization was carried out at 80 ° C. for 6 hours.

〔実施例１〕
＜樹脂組成物の調整＞
重合体Ａ１（１００ｇ）、エチレン性不飽和化合物（Ｂ）として東亜合成（株）アロニックスＭ８１００（６０ｇ）、東亜合成（株）アロニックスＭ３２０（１０ｇ）、感放射線性ラジカル重合開始剤（Ｃ）として２，２’−ビス（２−クロロフェニル）−４，５，４’，５’−テトラフェニル−１，２’−ビイミダゾール（４ｇ）、２−メチル−１−〔
４−（メチルチオ）フェニル〕−２−モンフォリノプロパノン−１（１０ｇ）、４，４’−ビス（ジエチルアミノ）ベンゾフェノン（０．２ｇ）、界面活性剤として（株）ネオス製ＦＴＸ−２１８（０．３ｇ）、溶媒として乳酸エチル（１５０ｇ）を混合し
、攪拌して均一な溶液を調製した。この成物溶液を、孔径１０μｍのカプセルフィルターでろ過して感放射線性樹脂組成物を得た。
〔実施例２〜１１および比較例１〜４〕
表２に従い、組成を変更した以外は実施例１と同様にして、感放射線性樹脂組成物を調製した。

[Example 1]
<Adjustment of resin composition>
Polymer A1 (100 g), Ethanolic unsaturated compound (B) as Toa Gosei Co., Ltd. Aronix M8100 (60 g), Toa Gosei Co., Ltd. Aronix M320 (10 g), Radiation sensitive radical polymerization initiator (C) 2 , 2′-bis (2-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl-1,2′-biimidazole (4 g), 2-methyl-1- [
4- (Methylthio) phenyl] -2-monforinopropanone-1 (10 g), 4,4′-bis (diethylamino) benzophenone (0.2 g), FTX-218 (manufactured by Neos Co., Ltd.) as a surfactant 0.3 g) and ethyl lactate (150 g) as a solvent were mixed and stirred to prepare a uniform solution. This composition solution was filtered through a capsule filter having a pore diameter of 10 μm to obtain a radiation sensitive resin composition.
[Examples 2 to 11 and Comparative Examples 1 to 4]
According to Table 2, the radiation sensitive resin composition was prepared like Example 1 except having changed the composition.

Example 12
<Adjustment of resin composition>
A radiation-sensitive resin composition was obtained in the same manner as in Example 1 except that Polymer A10 (100 g) and PGMEA (150 g) were used as a solvent.

実施例１〜１２および比較例１〜４で得られた感放射線性樹脂組成物を用いて、以下の方法によりレジストパターンおよびメッキ造形物を形成し、感放射線性樹脂膜および硬化膜の特性を評価した。結果を表３に示す。

Using the radiation sensitive resin compositions obtained in Examples 1 to 12 and Comparative Examples 1 to 4, a resist pattern and a plated model are formed by the following method, and the characteristics of the radiation sensitive resin film and the cured film are determined. evaluated. The results are shown in Table 3.

<Pattern formation>
The above resin composition was applied to a gold sputter substrate using a spin coater, and then heated on a hot plate at 110 ° C. for 5 minutes to form a resin film having a thickness of 25 μm. Next, ultraviolet light of 300 to 1000 mJ / cm ² was irradiated through a pattern mask using an ultrahigh pressure mercury lamp (HBO manufactured by OSRAM, output 1,000 W). The exposure amount was confirmed with an illuminometer (a probe UV-42 (light receiver) connected to UV-M10 (illuminometer) manufactured by Oak Manufacturing Co., Ltd.)). Development was performed using a 2.38 wt% tetramethylammonium hydroxide aqueous solution as a developer at room temperature, washed with running water, and blown with nitrogen to form a resist pattern. Hereinafter, the substrate on which the resist pattern is formed is referred to as a “patterning substrate”.

<Formation of plated objects>
The patterning substrate was subjected to an ashing treatment (output 100 W, oxygen flow rate 100 ml, treatment time 1 minute) by oxygen plasma as a pretreatment for electroplating to perform a hydrophilic treatment. Next, this substrate is subjected to electrolytic copper plating at 60 ° C., 0.5 A / dm ² , for 50 minutes or 75 minutes using Tempe Resist EX manufactured by Nippon Kogyo Chemical Co., Ltd. as a plating solution to form a bump of 15 μm height. did. Thereafter, THB-S2 (manufactured by JSR) was used as a peeling solution, and the resin film was peeled off by being stirred for 10 minutes at 50 ° C. to obtain a substrate having a plated model. Hereinafter, the substrate having the plated model is referred to as “plated substrate”.

<Resolution evaluation>
The patterning substrate was observed with a scanning electron microscope at 1000 times, and the resolution was measured. Here, the resolution is determined by resolving a square pattern having a mask design dimension of 50 μm × 50 μm, the resist is resolved without residual resist, and the angle between the side wall of the resist pattern and the substrate is 85 to 95 °. In other cases, “X” was assigned.

<Adhesion evaluation>
The adhesion to the substrate was evaluated by observing the cross section of the patterning substrate at 1500 times using a scanning electron microscope.

A case where no resist lift was observed around the opening or the edge of the wafer was indicated as “◯”, and a case where resist lift or resist peeling was observed was indicated as “X”.
<Evaluation of plating solution wettability>
The wettability to the plating solution is that when the patterning substrate is immersed in the plating solution, the surface of the patterning substrate has an affinity for the plating solution, and the defects inside the pattern are not generated by the complete elimination of bubbles inside the pattern. Evaluation was made by observing the plated substrate 10 times with an optical microscope as a reference.

  The case where there is no plating defect in the plated substrate or the plating defect of less than 5% is “◯”, the case where there is a plating defect in 5-30% is “△”, the case where there is a plating defect exceeding 30%. It was set as “x”.

<Evaluation of plating solution resistance>
For plating solution resistance, the patterning substrate is immersed in the plating solution to form bumps, washed with running water, blown with nitrogen gas, and dried (substrate with the resin film not peeled off) using an optical microscope. The substrate surface was observed and evaluated. The case where no resist lift was observed around the resist opening or the edge of the substrate was indicated as “◯”, and the case where resist lift or peeling was observed was indicated as “X”. At this time, the immersion test for 50 minutes was defined as the plating immersion time (short), and the immersion test for 75 minutes was defined as the plating immersion time (long).

<Evaluation of peelability>
Evaluation of peelability was performed by observing the test specimen from which the cured resist film was peeled after plating with a scanning electron microscope at a magnification of 1500 times.

The case where no residue is observed is indicated by “◯”, and the case where the residue is observed is indicated by “x”.
These evaluation results are summarized in Table 3.

Claims (9)

(A) a polymer containing a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2);
A negative radiation-sensitive resin composition comprising (B) a compound having at least one ethylenically unsaturated double bond, and (C) a radiation-sensitive radical polymerization initiator.

[In the formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear, cyclic or aromatic hydrocarbon group having 6 to 12 carbon atoms, or at least one hydrogen atom of these groups Represents a substituted hydrocarbon group substituted with a hydrocarbon group, R ⁴ represents a — (C _n H _2n ) — group, m is an integer of 1 to 10, and n is an integer of 2 to 4. ]

[In the formula (2), R ³ represents a hydrogen atom or a methyl group. ] The negative radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive radical polymerization initiator (C) contains a biimidazole compound represented by the following formula (3).

[In Formula (3), X represents a hydrogen atom, a methyl group, or a chlorine atom each independently, and Ph represents a phenyl group. ]   The negative radiation-sensitive resin composition according to claim 1 or 2, wherein the negative radiation-sensitive resin composition is a negative radiation-sensitive resin composition for producing a plated model.   The negative radiation-sensitive resin composition according to claim 3, wherein the plated model is a bump.   The negative radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the compound (B) is contained in an amount of 30 to 80 parts by weight with respect to 100 parts by weight of the polymer (A). .   The negative type according to any one of claims 1 to 5, wherein 1 to 40 parts by weight of the radiation-sensitive radical polymerization initiator (C) is contained with respect to 100 parts by weight of the polymer (A). Radiation sensitive resin composition.   The negative radiation-sensitive resin composition according to any one of claims 1 to 6, wherein the composition further comprises an organic solvent (D).   A transfer film comprising: a support film; and a resin film formed from the negative radiation-sensitive resin composition according to any one of claims 1 to 7 on the support film. (1) The process of forming the resin film formed from the negative radiation sensitive resin composition in any one of Claims 1-7 on the wafer which has a barrier metal layer,
(2) A step of developing the pattern after exposing the resin film,
(3) A step of depositing an electrode material by electrolytic plating using the pattern as a mold, and (4) a step of removing a barrier metal by etching after peeling off the remaining resin film, Manufacturing method.