JPWO2018181340A1 - Positive photosensitive resin composition, dry film, cured product, printed wiring board and semiconductor element - Google Patents

Abstract

A positive photosensitive resin composition having excellent developability (resolution and residual film ratio), and having excellent pattern formability after curing; a dry film having a resin layer obtained from the composition; Provided are a composition or a cured product of a resin layer of the dry film, a printed wiring board having the cured product, and a semiconductor element having the cured product. (A) a polybenzoxazole precursor, (B) a photoacid generator, (C) a crosslinking agent having a phenolic hydroxyl group, and (D) a crosslinking agent having no phenolic hydroxyl group and having two or more methylol groups. And a positive-type photosensitive resin composition.

Description

  The present invention relates to a positive photosensitive resin composition, a dry film, a cured product, a printed wiring board, and a semiconductor device.

  As a positive photosensitive resin composition that can be developed with an aqueous alkali solution, a composition in which a polybenzoxazole (PBO) precursor and a photoacid generator such as a naphthoquinonediazide compound are blended is used. A cured product of polybenzoxazole obtained by thermally curing such a composition is excellent in heat resistance and electrical insulation, so that a surface protective film or an interlayer insulating film of an electrical material, for example, a coating film of a semiconductor element, Applications to flexible printed wiring board materials and heat-resistant insulating interlayer materials are being promoted.

When the positive photosensitive resin composition containing such a polybenzoxazole precursor as a resin component has a high molecular weight of the polybenzoxazole precursor, a cured product thereof can obtain excellent mechanical properties. However, on the other hand, since the resin component is a high molecular weight substance, there is a problem that the developability of a coating film of such a composition is reduced.
On the other hand, conventionally, in a positive photosensitive resin composition containing a high molecular weight substance such as a polybenzoxazole precursor as a resin component, a dissolution promoter is added to improve the developability of a coating film. (Eg, Patent Document 1).
Indeed, the present inventors have noticed that the addition of a dissolution accelerator improves the developability of a coating film according to the prior art, but there is a new problem that it is difficult to control the pattern shape. .
On the other hand, a method of lowering the molecular weight of the resin component to improve the developability of the coating film can be considered. However, the present inventors have noticed that this method has various problems such as a decrease in the residual film ratio during development, deformation of the pattern shape after curing, and difficulty in controlling the rectangularity. .

JP 2009-145900 A

Therefore, a main object of the present invention is to provide a positive photosensitive resin composition having excellent developability (resolution and residual film ratio) and excellent pattern formation after curing, and a resin of the composition. It is to provide a dry film having a layer.
Another object of the present invention is to provide a cured product of the above-mentioned composition or the resin layer of the above-mentioned dry film, which is suitable for use in electronic components such as printed wiring boards and semiconductor elements.

  The present inventors have conducted intensive studies in view of the above, and as a result, have found that the above problems can be solved by using two specific compounds as crosslinking agents, and have completed the present invention.

  That is, the positive photosensitive resin composition of the present invention comprises (A) a polybenzoxazole precursor, (B) a photoacid generator, (C) a crosslinking agent having a phenolic hydroxyl group, and (D) a phenolic hydroxyl group. And a cross-linking agent having two or more methylol groups.

  The positive photosensitive resin composition of the present invention preferably further contains a silane coupling agent.

  The dry film of the present invention has a resin layer obtained by applying and drying the positive photosensitive resin composition on a film.

  The cured product of the present invention is obtained by curing the positive photosensitive resin composition or the resin layer of the dry film.

  A printed wiring board according to the present invention includes the cured product.

  A semiconductor device according to the present invention includes the cured product.

  According to the present invention, it is possible to provide a positive photosensitive resin composition having excellent developability (resolution and residual film ratio) and excellent pattern formation after curing. As a result, the positive photosensitive resin composition of the present invention and the dry film obtained from the composition, the cured product of the composition or the resin layer of the dry film are suitable for electronic parts such as printed wiring boards and semiconductor elements. Can be used.

  Hereinafter, the components contained in the positive photosensitive resin composition of the present invention will be described in detail.

[(A) Polybenzoxazole precursor]
The positive photosensitive resin composition of the present invention contains (A) a polybenzoxazole precursor. (A) The method for synthesizing the polybenzoxazole precursor is not particularly limited, and may be a known method. For example, it can be obtained by reacting a dihydroxydiamine as an amine component with a dicarboxylic acid dihalide such as dicarboxylic acid dichloride as an acid component.

（式中、Ｘは４価の有機基を示し、Ｙは２価の有機基を示す。ｎは１以上の整数であり、好ましくは１０〜５０、より好ましくは２０〜４０である。）(A) The polybenzoxazole precursor is preferably a polyhydroxyamic acid having the following repeating structure.

(In the formula, X represents a tetravalent organic group, and Y represents a divalent organic group. N is an integer of 1 or more, preferably 10 to 50, and more preferably 20 to 40.)

  (A) When the polybenzoxazole precursor is synthesized by the above method, in the general formula (1), X is a residue of the dihydroxydiamine, and Y is a residue of the dicarboxylic acid.

  Examples of the dihydroxydiamines include 3,3′-diamino-4,4′-dihydroxybiphenyl, 4,4′-diamino-3,3′-dihydroxybiphenyl, bis (3-amino-4-hydroxyphenyl) propane, Bis (4-amino-3-hydroxyphenyl) propane, bis (3-amino-4-hydroxyphenyl) sulfone, bis (4-amino-3-hydroxyphenyl) sulfone, 2,2-bis (3-amino-4 -Hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-amino-3-hydroxyphenyl) -1,1,1,3,3,3-hexa Fluoropropane and the like. Among them, 2,2-bis (3-amino-4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane is preferred.

  Examples of the dicarboxylic acid include isophthalic acid, terephthalic acid, 5-tert-butylisophthalic acid, 5-bromoisophthalic acid, 5-fluoroisophthalic acid, 5-chloroisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4 ′. -Dicarboxybiphenyl, 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxytetraphenylsilane, bis (4-carboxyphenyl) sulfone, 2,2-bis (p-carboxyphenyl) propane, 2,2 Dicarboxylic acid having an aromatic ring such as -bis (4-carboxyphenyl) -1,1,1,3,3,3-hexafluoropropane, oxalic acid, malonic acid, succinic acid, 1,2-cyclobutanedicarboxylic acid, Aliphatic compounds such as 1,4-cyclohexanedicarboxylic acid and 1,3-cyclopentanedicarboxylic acid And a carboxylate. Among them, 4,4'-dicarboxydiphenyl ether is preferred.

  In the general formula (1), the tetravalent organic group represented by X may be an aliphatic group or an aromatic group, but is preferably an aromatic group, and two hydroxy groups and two amino groups are located at ortho positions. More preferably, it is located on an aromatic ring. The tetravalent aromatic group preferably has 6 to 30 carbon atoms, more preferably 6 to 24 carbon atoms. Specific examples of the tetravalent aromatic group include, but are not limited to, the following groups.A known aromatic group that can be included in the polybenzoxazole precursor may be selected according to the application. I just need.

The tetravalent aromatic group is preferably the following group among the aromatic groups.

  In the general formula (1), the divalent organic group represented by Y may be either an aliphatic group or an aromatic group, but is preferably an aromatic group. More preferably, it is bonded to The divalent aromatic group preferably has 6 to 30 carbon atoms, and more preferably 6 to 24 carbon atoms. Specific examples of the divalent aromatic group include, but are not limited to, the following groups, provided that a known aromatic group contained in the polybenzoxazole precursor is selected according to the application. Good.

（式中、Ａは単結合、−ＣＨ_２−、−Ｏ−、−ＣＯ−、−Ｓ−、−ＳＯ_２−、−ＮＨＣＯ−、−Ｃ（ＣＦ_３）_２−、−Ｃ（ＣＨ_３）_２−からなる群から選択される２価の基を表す。）

(In the formula, A is a single _{bond, -CH 2 -, - O -} , - CO -, - S -, - SO 2 -, - NHCO -, - C (CF 3) 2 -, - C (CH 3) ₂ - represents a divalent radical selected from the group consisting of).

The divalent organic group is preferably the following group among the aromatic groups.

  (A) The polybenzoxazole precursor may contain two or more kinds of the above-mentioned polyhydroxyamic acid repeating structures. Further, it may include a structure other than the above-mentioned repeating structure of polyhydroxyamic acid, and may include, for example, a repeating structure of polyamic acid.

  (A) The number average molecular weight (Mn) of the polybenzoxazole precursor is preferably from 5,000 to 100,000, more preferably from 8,000 to 50,000. Here, the number average molecular weight is a value measured by GPC and converted into standard polystyrene. Further, the weight average molecular weight (Mw) of the polybenzoxazole precursor (A) is preferably from 10,000 to 200,000, more preferably from 16,000 to 100,000. Here, the weight average molecular weight is a value measured by GPC and converted into standard polystyrene. Mw / Mn is preferably from 1 to 5, more preferably from 1 to 3.

  As the polybenzoxazole precursor (A), one type may be used alone, or two or more types may be used in combination. (A) The blending amount of the polybenzoxazole precursor is preferably from 60 to 90% by mass based on the total solid content of the composition.

[(B) Photoacid generator]
(B) Photoacid generators include naphthoquinonediazide compounds, diarylsulfonium salts, triarylsulfonium salts, dialkylphenacylsulfonium salts, diaryliodonium salts, aryldiazonium salts, aromatic tetracarboxylic acid esters, aromatic sulfonic acid esters, Examples thereof include nitrobenzyl ester, aromatic N-oxyimidosulfonate, aromatic sulfamide, and benzoquinonediazosulfonic acid ester. (B) The photoacid generator is preferably a dissolution inhibitor. Among them, a naphthoquinonediazide compound is preferred.

  As the naphthoquinonediazide compound, specifically, for example, a naphthoquinonediazide adduct of tris (4-hydroxyphenyl) -1-ethyl-4-isopropylbenzene (for example, TKF-520 and TKF-528 manufactured by Sanbo Chemical Laboratory Co., Ltd.) , TKF-420, TKF-428), and naphthoquinonediazide adduct of tetrahydroxybenzophenone (for example, BS550, BS570, BS599, manufactured by Sanpo Chemical Laboratory). Here, the addition of naphthoquinonediazide may be performed by, for example, reacting o-quinonediazide sulfonyl chlorides with a hydroxy compound or an amino compound.

  (B) The photoacid generator may be used alone or in combination of two or more. (B) It is preferable that the compounding quantity of a photo-acid generator is 3 to 20 mass% based on the total solid content of the composition.

[(C) Crosslinking agent having phenolic hydroxyl group]
The positive photosensitive resin composition of the present invention contains (C) a crosslinking agent having a phenolic hydroxyl group as a crosslinking agent. (C) The crosslinking agent having a phenolic hydroxyl group is not particularly limited, but preferably has two or more hydroxyl groups (including a phenolic hydroxyl group), more preferably has two or more phenolic hydroxyl groups, and has the following general formula (2) Further preferred is a compound represented by the formula:

（一般式（２）中、Ｒ^１は２〜１０価の有機基を示す。Ｒ^２は、それぞれ独立に、水素原子または炭素数１〜４のアルキル基を示す。ｎは２〜１０の整数を示す。）

(In the general formula (2), R ¹ represents a divalent to divalent organic group. R ² each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. N is an integer of 2 to 10. Is shown.)

In the general formula (2), R ¹ is preferably an alkylene group having 1 to 3 carbon atoms which may have a substituent.

In the general formula (2), R ² is preferably a hydrogen atom.

  In the general formula (2), n is preferably an integer of 2 to 4, and more preferably 2.

Further, (C) the crosslinking agent having a phenolic hydroxyl group preferably has a fluorine atom, and more preferably has a trifluoromethyl group. The fluorine atom or the trifluoromethyl group preferably has a divalent to divalent organic group represented by R ¹ in the general formula (2), and R ¹ is a di (trifluoromethyl) methylene group Is preferred. Further, (C) the crosslinking agent having a phenolic hydroxyl group preferably has a bisphenol structure, and more preferably has a bisphenol AF structure.

The following compounds are preferred as specific examples of the crosslinking agent (C) having a phenolic hydroxyl group.

  As the crosslinking agent (C) having a phenolic hydroxyl group, one type may be used alone, or two or more types may be used in combination. (C) The compounding amount of the crosslinking agent having a phenolic hydroxyl group is preferably from 1 to 20% by mass, more preferably from 3 to 10% by mass, based on the total solid content of the composition. With such a mixing ratio, a composition having more excellent developability and more excellent pattern formation after curing can be obtained.

[(D) Crosslinking agent having two or more methylol groups without a phenolic hydroxyl group]
The positive photosensitive resin composition of the present invention contains (D) a crosslinking agent having no phenolic hydroxyl group and having two or more methylol groups as a crosslinking agent. This (D) crosslinking agent having no phenolic hydroxyl group and having two or more methylol groups preferably has a molecular weight of 100 or more.

  (D) The crosslinking agent having no phenolic hydroxyl group and having two or more methylol groups is more preferably a compound represented by the following general formula (3).

（一般式（３）中、ｎは１〜１０の整数を示し、ｎが１のとき、Ｒ^３はメチロール基（すなわち「−ＣＨ_２ＯＨ」）を表し、ｎが２〜１０の整数のとき、Ｒ^３は２〜１０価の有機基を示す。Ｒ^４は、それぞれ独立に、炭素数１〜４の有機基を示す。ｍ１は１〜５の整数を示し、ｍ２は０〜４の整数を示す。）

(In the general formula (3), n represents an integer of 1 to 10, when n is 1, R ³ represents a methylol group (that is, “—CH ₂ OH”), and when n is an integer of 2 to 10, , R ³ represents a divalent to divalent organic group, R ⁴ represents each independently an organic group having 1 to 4 carbon atoms, m1 represents an integer of 1 to 5, and m2 represents an integer of 0 to 4. Is shown.)

  In the general formula (3), n is preferably 1.

In the general formula (3), R ⁴ is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group.

(D) Specific examples of the crosslinking agent having no phenolic hydroxyl group and having two or more methylol groups are preferably the following compounds.

As the crosslinking agent (D) having no phenolic hydroxyl group and having two or more methylol groups, one type may be used alone, or two or more types may be used in combination. The amount of the crosslinking agent (D) having no phenolic hydroxyl group and having two or more methylol groups is preferably 1 to 20% by mass, and preferably 3 to 10% by mass, based on the total solid content of the composition. Is more preferable. With such a mixing ratio, a composition having more excellent developability and more excellent pattern formation after curing can be obtained.
As the two types of cross-linking agents described above, (C) a cross-linking agent having a phenolic hydroxyl group has a function of accelerating dissolution, and (D) a cross-linking agent having no phenolic hydroxyl group and having two or more methylol groups, It has the function of dissolution inhibition. Therefore, in order to obtain better developability (resolution and residual film ratio), the compounding ratio is preferably (C) :( D) = 0.3 to 1: 1 to 0.3. , More preferably 4: 6 to 6: 4, and further preferably (C) :( D) = 1: 1.

(Silane coupling agent)
The positive photosensitive resin composition of the present invention may contain a silane coupling agent. By including the silane coupling agent, the adhesion to the substrate can be improved. The silane coupling agent is not particularly limited, for example, a silane coupling agent having an alkoxy group, a silane coupling agent having an amino group, a silane coupling agent having a mercapto group, a silane coupling agent having an epoxy group, an ethylenic Examples thereof include a silane coupling agent having an unsaturated group and a silane coupling agent having an arylamino group.

  One of these silane coupling agents may be used alone, or two or more thereof may be used in combination. The amount of the silane coupling agent is preferably 1 to 15% by mass based on the total solid content of the composition. When the content is 1 to 15% by mass, it is possible to prevent the undeveloped portion of the exposed portion while maintaining the adhesion to the substrate.

  Hereinafter, other components that can be added to the positive photosensitive resin composition of the present invention will be described.

The positive photosensitive resin composition of the present invention can contain a solvent. Examples of the solvent include (A) a polybenzoxazole precursor, (B) a photoacid generator, (C) a crosslinking agent having a phenolic hydroxyl group, and (D) crosslinking having no phenolic hydroxyl group and having two or more methylol groups. There is no particular limitation as long as it dissolves the agent and other additives. Examples include N, N′-dimethylformamide, N-methylpyrrolidone, N-ethyl-2-pyrrolidone, N, N′-dimethylacetamide, diethylene glycol dimethyl ether, cyclopentanone, γ-butyrolactone, α-acetyl-γ- Examples include butyrolactone, tetramethylurea, 1,3-dimethyl-2-imidazolinone, N-cyclohexyl-2-pyrrolidone, dimethyl sulfoxide, hexamethylphosphoramide, pyridine, γ-butyrolactone, and diethylene glycol monomethyl ether.
Such a solvent may be used alone or in combination of two or more. The amount of the solvent can be used in the range of 50 to 9000 parts by mass based on 100 parts by mass of the polybenzoxazole precursor (A), depending on the coating film thickness and the viscosity.

  A known sensitizer may be added to the positive photosensitive resin composition of the present invention in order to further improve photosensitivity.

  In addition, the positive photosensitive resin composition of the present invention may contain a known adhesion aid for improving the adhesion to the substrate.

  In order to impart processing characteristics and various functions to the positive photosensitive resin composition of the present invention, various other organic or inorganic low-molecular or high-molecular compounds may be blended. For example, a surfactant, a leveling agent, a plasticizer, fine particles, and the like can be used. The fine particles include organic fine particles such as polystyrene and polytetrafluoroethylene, and inorganic fine particles such as colloidal silica, carbon, and layered silicate. Further, various colorants, fibers and the like may be added to the positive photosensitive resin composition of the present invention.

[Dry film]
The dry film of the present invention has a resin layer obtained by coating and drying the positive photosensitive resin composition of the present invention on the film. The dry film of the present invention is used by laminating a resin layer so as to be in contact with a substrate.

  The dry film of the present invention is, for example, uniformly coated on a carrier film by a suitable method such as a blade coater, a lip coater, a comma coater, a film coater, and the like, and dried on a carrier film. It can be manufactured by forming a cured resin layer, and preferably laminating a cover film thereon. The cover film and the carrier film may be the same film material or different films.

  In the dry film of the present invention, as the film material of the carrier film and the cover film, any of those known as materials used for the dry film can be used.

  As the carrier film, for example, a thermoplastic film such as a polyester film such as polyethylene terephthalate having a thickness of 2 to 150 μm is used.

  As the cover film, a polyethylene film, a polypropylene film, or the like can be used, but a film having an adhesive force to the resin layer smaller than that of the carrier film is preferable.

  The thickness of the resin layer on the dry film of the present invention is preferably 100 μm or less, more preferably 5 to 50 μm.

  Using the positive photosensitive resin composition of the present invention, a pattern film as a cured product thereof is produced, for example, as follows.

First, in Step 1, a positive photosensitive resin composition is applied to a substrate and dried, or a resin layer is transferred from the dry film to the substrate to obtain a coating film.
As a method of applying the positive photosensitive resin composition on the substrate, a method conventionally used for applying the photosensitive resin composition, for example, a spin coater, a bar coater, a blade coater, a curtain coater, screen printing For example, a method of applying with a sprayer, a method of spray-coating with a spray coater, and an inkjet method can be used.
As a method for drying the coating film, methods such as air drying, heating drying using an oven or a hot plate, and vacuum drying are used. The drying of the coating film is desirably performed under such conditions that ring closure of the polybenzoxazole precursor (A) in the photosensitive resin composition does not occur. Specifically, natural drying, blast drying, or heat drying can be performed at 70 to 140 ° C. for 1 to 30 minutes. Preferably, drying is performed on a hot plate for 1 to 20 minutes. Vacuum drying is also possible. In this case, the drying can be performed at room temperature for 20 minutes to 1 hour.

  The substrate is not particularly limited, and can be widely applied to semiconductor substrates such as silicon wafers, wiring boards, various resins, metals, and the like.

Next, as a step 2, the coating film is exposed through a photomask having a pattern or directly.
The exposure light having a wavelength capable of activating the photoacid generator (B) and generating an acid is used. Specifically, the exposure light beam preferably has a maximum wavelength in the range of 350 to 450 nm. As described above, the light sensitivity can be adjusted by appropriately using a sensitizer.
As the exposure device, a contact aligner, a mirror projection, a stepper, a laser direct exposure device, or the like can be used.

Subsequently, as Step 3, heating may be performed to close a part of the polybenzoxazole in the unexposed portion (A).
Here, the ring closure rate is about 30%. The heating time and the heating temperature are appropriately changed depending on (A) polybenzoxazole, coating film thickness, and (B) the type of photoacid generator.

Next, as step 4, the coating film is treated with a developer.
This makes it possible to form a pattern film of the positive photosensitive resin composition of the present invention by removing the exposed portions in the coating film.
As a method used for development, any method can be selected from conventionally known methods for developing a photoresist, for example, a rotary spray method, a paddle method, an immersion method involving ultrasonic treatment, and the like.
Examples of the developer include inorganic alkalis such as sodium hydroxide, sodium carbonate, sodium silicate, and aqueous ammonia; organic amines such as ethylamine, diethylamine, triethylamine, and triethanolamine; tetramethylammonium hydroxide; and tetrabutylammonium hydroxide. And aqueous solutions of quaternary ammonium salts. If necessary, an appropriate amount of a water-soluble organic solvent such as methanol, ethanol, or isopropyl alcohol or a surfactant may be added to these. Further, the above-mentioned solvent may be used as a developer.
Thereafter, if necessary, the coating film is washed with a rinsing liquid to obtain a pattern film.
As the rinsing liquid, distilled water, methanol, ethanol, isopropyl alcohol and the like can be used alone or in combination.

Then, as a step 5, the pattern film is heated to obtain a cured coating film (cured product).
At this time, (A) the polybenzoxazole precursor may be closed to obtain polybenzoxazole.
The heating temperature is appropriately set so that the polybenzoxazole pattern film can be cured. For example, heating is performed at 150 to 350 ° C. for about 5 to 120 minutes in an inert gas. A more preferable range of the heating temperature is 200 to 320 ° C.
This heating is performed by using, for example, a hot plate, an oven, and a temperature rising oven in which a temperature program can be set. As the atmosphere (gas) at this time, air may be used, or an inert gas such as nitrogen or argon may be used.

  The use of the positive photosensitive resin composition of the present invention is not particularly limited. For example, printing inks, adhesives, fillers, electronic materials, optical circuit parts, molding materials, resist materials, building materials, three-dimensional modeling, optics Various known fields and products in which a resin material is used, such as members, may be used. In particular, a wide range of fields and products in which the properties such as heat resistance, dimensional stability, and insulation properties of the polybenzoxazole film are effective, such as paints or printing inks, color filters, flexible display films, and semiconductor device coatings. It is suitably used as a coating film of a printed wiring board such as a coating film, an electronic component, an interlayer insulating film, and a solder resist, an optical circuit, an optical circuit component, an antireflection film, a hologram, an optical member, or a building material.

  In particular, the positive photosensitive resin composition of the present invention is mainly used as a pattern forming material (resist), and the pattern film formed thereby imparts heat resistance and insulation as a permanent film made of polybenzoxazole. For example, color filters, flexible display films, insulating materials for passive components, coating films for semiconductor devices, interlayer insulating films, coating films for printed wiring boards such as solder resists and coverlay films, solder dams It is suitable for forming optical circuits, optical circuit components, antireflection films, and other optical or electronic members.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. In the following, “parts” and “%” are all based on mass unless otherwise specified.

(Synthesis of polybenzoxazole (PBO) precursor)
In a 0.5-liter flask equipped with a stirrer and a thermometer, 212 g of N-methylpyrrolidone was charged, and 17.55 g (47.93 mmol) of bis (3-amino-4-hydroxyamidophenyl) hexafluoropropane was stirred and dissolved. Thereafter, the flask was immersed in an ice bath, and while keeping the inside of the flask at 0 to 5 ° C., 15.00 g (50.83 mmol) of 4,4-diphenyletherdicarboxylic acid chloride was added as a solid in 5 g portions over 30 minutes. For 30 minutes. Thereafter, stirring was continued at room temperature for 5 hours. The stirred solution was poured into 1 L of ion-exchanged water (specific resistance value: 18.2 MΩ · cm) to collect a precipitate. Thereafter, the obtained solid was dissolved in 420 mL of acetone, and poured into 1 L of ion-exchanged water. The precipitated solid was collected and dried under reduced pressure to obtain a polybenzoxazole (PBO) precursor A-1 having a carboxyl group terminal having the following repeating structure. The number average molecular weight (Mn) of the polybenzoxazole precursor A-1 was 17,300, the weight average molecular weight (Mw) was 42,100, and Mw / Mn was 2.45.

(Examples 1 to 7, Comparative Examples 1 to 3)
Based on 100 parts by mass of the benzoxazole precursor (A-1) synthesized above, 10 parts by mass of a naphthoquinonediazide (DNQ) compound (B-1), a crosslinking agent shown in Table 1 below, and a silane coupling agent (E -1) After mixing 7 parts by mass, N-methylpyrrolidone (NMP) was added so that the benzoxazole precursor became 30% by mass to form a varnish, which was applied on a silicon substrate using a spin coater. It was dried on a hot plate at 120 ° C. for 3 minutes to obtain a dried film of the photosensitive resin composition. The obtained dried coating film was irradiated with 300 mJ / cm ² broad light using a high-pressure mercury lamp through a mask having a pattern of 1 to 30 μm. After exposure, the resist film was developed with a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) for 60 seconds and rinsed with water to obtain a positive pattern.
(B-1), (C-1), (C-2), (C-3), (D-1), (D-2), (D-3) and (E-1) are as follows. Compound.

(B-1)

（Ｃ−３）

(C-1) (C-2)

(C-3)

（Ｄ−３）

(D-1) (D-2)

(D-3)

(E-1)

(Evaluation of unexposed portion residual film ratio)
The film thickness of the photosensitive film after development was measured, and the ratio to the film thickness before development was determined to determine the unexposed portion residual film ratio.

(Evaluation of resolution)
After development, the pattern was observed with an electron microscope (SEM “JSM-6010”), and the minimum pattern size that allowed patterning of the exposed portion without scum was defined as resolution (L (μm) / S (μm)).

(Pattern formation after curing)
The positive type pattern was subjected to a heat treatment at 150 ° C. for 30 minutes / 320 ° C. for 1 hour and cured, then the pattern shape was observed with an electron microscope (SEM “JSM-6010”) and evaluated according to the following criteria. .
：: When the pattern shape is a rectangle or a shape close to a rectangle X: When the pattern shape is a shape close to a circle with no corners

表中の括弧内の数値は、各成分の配合量（質量部）を示す。

The numerical values in parentheses in the table indicate the amounts (parts by mass) of the components.

  From the results shown in Table 1, the positive photosensitive resin composition of the present invention containing the above two specific crosslinking agents is excellent in resolution and residual film ratio, and has a positive pattern having an excellent shape. It can be seen that can be formed. In particular, it can be seen that the case where the compounding ratio of (C-1) and (D-1) in Example 1 is 1: 1 has the best balance of the evaluation results regarding the unexposed portion residual film ratio, resolution and pattern shape. .

Claims (6)

(A) a polybenzoxazole precursor,
(B) a photoacid generator,
(C) a crosslinking agent having a phenolic hydroxyl group, and
(D) A positive photosensitive resin composition comprising a crosslinking agent having no phenolic hydroxyl group and having two or more methylol groups.   2. The positive photosensitive resin composition according to claim 1, further comprising a silane coupling agent.   A dry film comprising a resin layer obtained by applying and drying the positive photosensitive resin composition according to claim 1 on a film.   A cured product obtained by curing the positive photosensitive resin composition according to claim 1 or 2 or the resin layer of the dry film according to claim 3.   A printed wiring board comprising the cured product according to claim 4.   A semiconductor device comprising the cured product according to claim 4.