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# NEGATIVE TYPE PHOTOSENSITIVE RESIN COMPOSITION, PHOTOSENSITIVE RESIST FILM, PATTERN FORMING METHOD, CURED FILM, AND METHOD OF PRODUCING CURED FILM 

[0001] The present invention relates to a negative type photosensitive resin composition, a photosensitive resist film having a photosensitive resin film formed by using the negative type photosensitive resin composition, a pattern forming method, a cured film, and a method of producing the cured film. 

[0002] Priority is claimed on Japanese Patent Application No. 2016-170206, filed on Aug. 31, 2016, the content of which is incorporated herein by reference. 

[0003] In recent years, with miniaturization and densifi› cation of electronic components, there has been an increas› ing demand for a photosensitive resin composition used for an electronic component having a hollow sealing structure, such as a surface acoustic wave (SAW) filter. In formation of the hollow sealing structure of such an electronic com› ponent, it is necessary to reduce the thickness of a cured film formed by curing a photosensitive resin composition and to strengthen the cured film. 

[0004] Further, a photosensitive resin composition is used for a spacer between a semiconductor wafer and a transpar› ent substrate. For example, a spacer is obtained, using a negative photosensitive resin composition, by forming a photosensitive resin film on a surface of a semiconductor wafer or the like, performing selective exposure on the photosensitive resin film to radiation such as light or elec› tronic beams, performing a development treatment to form a pattern, and pressure-bonding the pattern to a transparent substrate (for example, a glass substrate). In this photosen› sitive resin composition, it is necessary to perform pattern› ing in an excellent shape without residues during the devel› opment treatment according to a photolithography method. 

[0005] In the related art, a photosensitive resin composi› tion that contains a polyfunctional epoxy resin, a cationic polymerization initiator, a solvent, and a surfactant is dis› closed as a photosensitive material forming the photosensi› tive resin film (see PTL 1). 

[0006] [PTL 1] Japanese Unexamined Patent Application, First Publication No. 2008-250200 

[0007] However, in a case where the thickness of the cured film is reduced using the photosensitive resin composition described in PTL 1 and miniaturization of the hollow sealing structure is attempted, the hardness of the cured thin film against a processing pressure under a high temperature (150° C. to 200° C.) condition during molding is insufficient, and thus it is difficult to maintain the hollow sealing structure. 

## TECHNICAL FIELD 

## BACKGROUND ART 

## CITATION LIST 

## Patent Literature 

## SUMMARY OF INVENTION 

## Technical Problem 

[0008] The present invention has been made in consider› ation of the above-described problems, and an object thereof is to provide a negative type photosensitive resin composi› tion from which a cured film having improved hardness can be obtained and a pattern having an excellent shape can be formed; a photosensitive resist film which has a photosen› sitive resin film formed by using the negative type photo› sensitive resin composition; a pattern forming method; a cured film; and a method of producing the cured film. 

[0009] According to a first aspect of the present invention, there is provided a negative type photosensitive resin com› position containing: an epoxy group-containing resin (A); a metal oxide (M); and a cationic polymerization initiator (I), the cationic polymerization initiator (I) containing one or more selected from the group consisting of a compound represented by Formula (Il) and a compound represented by Formula (I2). 

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[0010] [In the formulae, R 601 to R$^{04 }$each independently represent an aryl group which may have a substituent or a fluorine atom. R 605 represents a fluorinated alkyl group which may have a substituent or a fluorine atom. A plurality ofR$^{605}$’s may be the same as or different from one another. q represents an integer of 1 or greater, and Qq+,s each independently represent a q-valent organic cation.] 

[0011] According to a second aspect of the present inven› tion, there is provided a photosensitive resist film which is obtained by laminating a base film, a photosensitive resin film formed using the negative type photosensitive resin composition according to the first aspect, and a cover film in that order. 

[0012] According to a third aspect of the present inven› tion, there is provided a pattern forming method including: a step of forming a photosensitive resin film on a support using the negative type photosensitive resin composition according to the first aspect or the photosensitive resist film according to the second aspect; a step of exposing the photosensitive resin film; and a step of developing the exposed photosensitive resin film to form a negative type pattern. 

[0013] According to a fourth aspect of the present inven› tion, there is provided a cured film which is obtained by curing the negative type photosensitive resin composition according to the first aspect. 

[0014] According to a fifth aspect of the present invention, there is provided a method of producing a cured film, including: a step of forming a photosensitive resin film on a support using the negative type photosensitive resin com› position according to the first aspect or the photosensitive resist film according to the second aspect; and a step of curing the photosensitive resin film to obtain a cured film. 

## Solution to Problem 

(11) 

(12) 

