JPWO2017149563A1 - Photosensitive resin composition, pattern forming method using the same, and circuit forming substrate - Google Patents

Abstract

(A) A polymer having a structural unit represented by the following formula (A), and (b) a compound represented by the following formula (B) and a compound represented by the following formula (BB) that generate radicals upon irradiation with actinic rays. The photosensitive resin composition containing the compound (In formula (BB), R51 is group represented by Formula (11), or the same group as R50).

Description

  The present invention relates to a photosensitive resin composition, a pattern forming method using the same, and a circuit forming substrate.

  Conventionally, polyimide resins having excellent heat resistance, electrical characteristics, mechanical characteristics, and the like have been used for surface protection films and interlayer insulating films of semiconductor elements. In recent years, however, semiconductor devices have been highly integrated and increased in size, and the sealing resin package has been required to be thinner and smaller, and LOC (lead-on-chip) and surface mounting methods such as solder reflow have been adopted. A polyimide resin excellent in mechanical properties, heat resistance and the like has been required more than ever.

  On the other hand, photosensitive polyimide having a photosensitive property imparted to the polyimide resin itself has been used. However, if this is used, the pattern production process can be simplified and complicated manufacturing processes can be shortened.

  In recent years, attention has been focused on applying such photosensitive polyimide to a circuit forming substrate on a suspension on which a magnetic head of a hard disk drive described below is mounted.

  From the viewpoint of increasing the storage capacity and speed of the hard disk drive, as a magnetic head, a magnetoresistive MR (Magnetic Resistive) element and a thin film replace the conventional MIG (Metal In Gap) or magnetic induction type thin film. A so-called MR-thin film composite type head in which is integrated is attracting attention.

In contrast to the conventional head that reads and writes magnetic signals with one head, the MR head doubles the number of terminals (adding a grounding terminal if necessary) to read and write within one head. Therefore, the wire connecting the head and the disk main body needs to be thinned.
However, when thinning is performed, the wire tends to corrode easily. In addition, there arises a problem that impedance matching is difficult and a head is difficult to mount. As a method for solving such a new problem, a method of directly forming a circuit on a suspension on which a head is mounted has been proposed (see Patent Documents 1 and 2).

JP 2010-266843 A US Patent Application Publication No. 2013-143011

JOURNAL OF MICROELECTROMECHANICAL SYSTEMs, 1483-1488, VOL. 20, NO. 6, DECEMBER 2011

  A polyimide resin layer having excellent heat resistance, electrical characteristics, mechanical characteristics, and the like is used for the circuit forming substrate as described above as an interlayer insulating film or a protective layer of a circuit. As described in Patent Document 1, when forming a stepped circuit, the first layer of polyimide resin is applied, exposed, developed and cured, and then the second layer is applied, exposed, developed and cured. Therefore, it is necessary to form a stepped circuit, and the problem is that the process becomes long and the cost is high.

  By the way, in recent years, in the formation of a complicated structure such as a microlens, application of a gray scale mask in which the light transmittance is controlled by applying light and shade to the mask has been studied (Non-patent Document 1). It has been found that this method can greatly shorten the process and form a complicated structure having a step.

  Therefore, for the purpose of manufacturing suspensions for hard disk drives, we tried to create a stepped shape by patterning using a gray scale mask, but the conventional photosensitive polyimide resin that has both low thermal expansion and low hygroscopic expansion. Since the gamma value is high, there is no difference between the remaining film rate at low exposure and the remaining film rate at high exposure, and the remaining film rate is large due to slight exposure blurring in the gray scale part. It has been found that there is a problem that it is difficult to form a step shape and the process tolerance is low because of the change. Further, it has been newly found out that there is a problem that the amount of exposure becomes low in the gray scale portion, so that the resin oozes out after development due to insufficient crosslinking.

  An object of the present invention is to provide a photosensitive resin composition having a process tolerance that can sufficiently form a pattern having a step when exposed using a gray scale mask, and a pattern forming method and circuit using the same. It is to provide a forming substrate.

（式（Ａ）中、Ｒ^１は３価又は４価の有機基、Ｒ^２は２価の有機基、Ｒは、炭素炭素不飽和二重結合を有する一価の有機基又はＯ⁻Ｍ^＋で表される基であり、Ｍ^＋は、水素イオン又は炭素炭素不飽和二重結合を有する化合物のイオンであり、Ｒの少なくとも１つは、炭素炭素不飽和二重結合を有する一価の有機基か、Ｏ⁻Ｍ^＋で表される基であってかつＭ^＋が炭素炭素不飽和二重結合を有する化合物のイオンであり、ｎは１又は２である。）

（式（Ｂ）中、Ｒ^１１及びＲ^１２は、それぞれ独立に、炭素数１〜２０のアルキル基、フェニル基、カルバゾール基又はフルオレニル基である。前記アルキル基、フェニル基、カルバゾール基及びフルオレニル基は置換基を有してもよい。前記カルバゾール基が複数の置換基を有する場合、隣り合う置換基同士は結合して環を形成してもよい。）

（式（ＢＢ）中、Ｒ^５０は、炭素数１〜２０のアルキル基、１以上のエーテル結合を含む炭素数２〜２０のアルキル基、炭素数１〜１２のアルコキシ基、炭素数１〜４のアルキル基又は１以上のエーテル結合を含む炭素数２〜２０のアルキル基で置換されたフェニル基、フェニル基、ハロゲン原子、炭素数１〜１２のアルケニル基、又はビフェニリル基であり、Ｒ^５１は、式（１１）で表される基、又は上記Ｒ^５０と同じの基であり、Ｒ^５２〜Ｒ^５４は、各々独立に、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基又はハロゲン原子である。）

（式（１１）中、Ｒ^５５〜Ｒ^５７は、各々独立に、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基又はハロゲン原子である。）
２．前記（ａ）成分が、下記式（１）で表わされる構造単位を有するポリマーである１に記載の感光性樹脂組成物。

（式（１）中、Ｒ^１、Ｒ^２、Ｍ^＋及びｎは、それぞれ、前記式（Ａ）のＲ^１、Ｒ^２、Ｍ^＋及びｎと同じである。）
３．Ｒ^２が、下記式（２）又は（３）で表わされる構造である１又は２に記載の感光性樹脂組成物。

（式（２），（３）中、複数あるＲ^４は、各々独立に、フッ素原子、又は酸素原子、硫黄原子若しくはハロゲン原子を有していてもよい炭素数１〜１０の１価の有機基を表す。ｓ、ｔ及びuは各々独立に０〜４の整数を表す。）
４．Ｒ^２が、下記式（４）で表わされる構造である１又は２に記載の感光性樹脂組成物。

（式（４）中、Ｒ^５は各々独立にフッ素原子又はトリフルオロメチル基である。）
５．前記式（Ｂ）で表される化合物が、下記式（６）又は（７）で表される化合物である１〜４のいずれかに記載の感光性樹脂組成物。

（式（６）及び（７）中、Ｒ^１１は前記式（Ｂ）のＲ^１１と同じである。Ｒ^１４〜Ｒ^２０はそれぞれ独立して水素原子、−ＮＯ_２基又は下記式（８）で表される基である。ＸはＣ（Ｒ^３）_２又はＮＲ^３である。Ｒ^３は、それぞれ独立に、水素原子又は炭素数１〜２０のアルキル基である。）

（Ｒ^２１は、それぞれ独立に、１価の有機基である。ｐは０〜５の整数である）
６．前記式（Ｂ）で表される化合物が、下記式（Ｂ−３）〜（Ｂ−７）で表される化合物のいずれかである１〜４のいずれかに記載の感光性樹脂組成物。

７．前記式（ＢＢ）で表される化合物が、下記式（ＢＢ−１）又は（ＢＢ−２）で表される化合物である１〜６のいずれかに記載の感光性樹脂組成物。

８．前記（ｂ）成分の含有量が、前記（ａ）成分１００質量部に対して、０．１〜２０質量部である１〜７のいずれかに記載の感光性樹脂組成物。
９．ハードディスクドライブサスペンション用である１〜８のいずれかに記載の感光性樹脂組成物。
１０．グレイスケールマスク露光用である１〜９のいずれかに記載の感光性樹脂組成物。
１１．１〜１０のいずれかに記載の感光性樹脂組成物を、基板上に塗布、乾燥して感光性樹脂膜を形成する工程と、
前記感光性樹脂膜を露光する工程と、
露光後の樹脂膜を現像する工程と、
現像後の樹脂膜を加熱処理する工程と
を含むパターン形成方法。
１２．１〜１０のいずれかに記載の感光性樹脂組成物の硬化物。
１３．１２に記載の硬化物を、層間絶縁膜又は保護膜として有する回路形成基板。
１４．支持基板と、層間絶縁膜と、導電層と、保護膜をこの順に含み、
前記層間絶縁膜と保護膜の少なくとも１つが１２に記載の硬化物である回路形成基板。
１５．１３又は１４に記載の回路形成基板を含むハードディスクドライブ用サスペンション。According to the present invention, the following photosensitive resin composition, a pattern forming method using the same, and a circuit forming substrate are provided.
1. (A) A polymer having a structural unit represented by the following formula (A), and (b) a compound represented by the following formula (B) and a compound represented by the following formula (BB) as a compound that generates radicals upon irradiation with actinic rays. The photosensitive resin composition containing the compound made.

(In formula (A), R ¹ is a trivalent or tetravalent organic group, R ² is a divalent organic group, R is a monovalent organic group having a carbon-carbon unsaturated double bond, or O ⁻ M ^+. M ⁺ is a hydrogen ion or an ion of a compound having a carbon-carbon unsaturated double bond, and at least one of R is a monovalent organic compound having a carbon-carbon unsaturated double bond. Or a group represented by O ⁻ M ⁺ and M ⁺ is an ion of a compound having a carbon-carbon unsaturated double bond, and n is 1 or 2.)

(In the formula (B), R ¹¹ and R ¹² are each independently an alkyl group having 1 to 20 carbon atoms, a phenyl group, a carbazole group, or a fluorenyl group. The alkyl group, phenyl group, carbazole group, and fluorenyl group. (In the case where the carbazole group has a plurality of substituents, adjacent substituents may be bonded to form a ring.)

(In the formula (BB), R ⁵⁰ represents an alkyl group having 1 to 20 carbon atoms, an alkyl group having 2 to 20 carbon atoms including one or more ether bonds, an alkoxy group having 1 to 12 carbon atoms, or 1 to 4 carbon atoms. Or a phenyl group, a phenyl group, a halogen atom, an alkenyl group having 1 to 12 carbon atoms, or a biphenylyl group substituted with an alkyl group having 2 to 20 carbon atoms containing one or more ether bonds, and R ⁵¹ is , A group represented by formula (11), or the same group as R ⁵⁰ described above, and R ^{52 to} R ⁵⁴ are each independently an alkyl group having 1 to 12 carbon atoms and an alkoxy group having 1 to 12 carbon atoms. Or a halogen atom.)

(In the formula ^(11), R 55 ^{to R 57} each independently represent an alkyl group having 1 to 12 carbon atoms, an alkoxy group or a halogen atom having 1 to 12 carbon atoms.)
2. 2. The photosensitive resin composition according to 1, wherein the component (a) is a polymer having a structural unit represented by the following formula (1).

(In the formula ^{(1), R 1, R} 2, M + and n are each the same as ^{R 1, R 2, M +} and n in the formula (A).)
3. The photosensitive resin composition of 1 or ² whose R < ² > is a structure represented by following formula (2) or (3).

(In the formulas (2) and (3), a plurality of R ⁴ are each independently a monovalent organic compound having 1 to 10 carbon atoms which may have a fluorine atom, an oxygen atom, a sulfur atom or a halogen atom. S, t and u each independently represents an integer of 0 to 4)
4). The photosensitive resin composition of 1 or ² whose R < ² > is a structure represented by following formula (4).

(In Formula (4), each R ⁵ is independently a fluorine atom or a trifluoromethyl group.)
5. The photosensitive resin composition in any one of 1-4 whose compound represented by the said Formula (B) is a compound represented by following formula (6) or (7).

(In the formulas (6) and (7), R ¹¹ is the same as R ^{11 in the} formula (B). R ^{14 to} R ²⁰ are each independently a hydrogen atom, —NO ₂ group or the following formula (8). X is C (R ³ ) ₂ or NR ^3. Each R ³ is independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.)

(R ²¹ is each independently a monovalent organic group. P is an integer of 0 to 5)
6). The photosensitive resin composition in any one of 1-4 whose compounds represented by the said Formula (B) are either of the compounds represented by following formula (B-3)-(B-7).

7). The photosensitive resin composition in any one of 1-6 whose compound represented by the said formula (BB) is a compound represented by a following formula (BB-1) or (BB-2).

8). The photosensitive resin composition in any one of 1-7 whose content of the said (b) component is 0.1-20 mass parts with respect to 100 mass parts of said (a) component.
9. The photosensitive resin composition in any one of 1-8 which is an object for hard disk drive suspensions.
10. The photosensitive resin composition in any one of 1-9 which is an object for gray scale mask exposure.
Applying the photosensitive resin composition according to any one of 11.1 to 10 on a substrate and drying to form a photosensitive resin film;
Exposing the photosensitive resin film;
Developing the resin film after exposure;
And a step of heat-treating the resin film after development.
Hardened | cured material of the photosensitive resin composition in any one of 12.1-10.
A circuit forming substrate having the cured product according to 13.12 as an interlayer insulating film or a protective film.
14 Including a support substrate, an interlayer insulating film, a conductive layer, and a protective film in this order,
A circuit forming substrate, wherein at least one of the interlayer insulating film and the protective film is a cured product according to 12.
15. Suspension for hard disk drive including the circuit forming substrate according to 15.13 or 14.

  According to the present invention, a photosensitive resin composition having a process margin that can sufficiently form a pattern having a step when exposed using a gray scale mask, a pattern forming method and a circuit using the same. A forming substrate can be provided.

It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of forming a pattern using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic plan view which shows the suspension for hard disk drives manufactured using the photosensitive resin composition concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape. It is a schematic sectional drawing explaining the process of providing the polyimide resin layer which is the conventional method, and forming the pattern which has a level | step difference shape.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the present specification, “A or B” only needs to include either A or B, and may include both. In addition, in this specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used as long as the intended action of the process is achieved. included.
The numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. In addition, in the present specification, the content of each component in the composition is the sum of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. Means quantity. Further, the exemplary materials may be used singly or in combination of two or more unless otherwise specified.

  In the present specification, “(meth) acrylate” means “acrylate” and “methacrylate” corresponding thereto.

  The photosensitive resin composition of the present invention comprises (a) a polymer having a structural unit represented by the following formula (A) (hereinafter sometimes referred to as component (a)), and (b) radicals by irradiation with actinic rays. As a compound which generate | occur | produces, the compound represented by the following formula (B) and the compound represented by the following formula (BB) (Hereinafter, it may be called (b) component.) Is included.

式（Ａ）中、Ｒ^１は３価又は４価の有機基、Ｒ^２は２価の有機基、Ｒは、炭素炭素不飽和二重結合を有する一価の有機基又はＯ⁻Ｍ^＋で表される基であり、Ｍ^＋は、水素イオン又は炭素炭素不飽和二重結合を有する化合物のイオンであり、Ｒの少なくとも１つは、炭素炭素不飽和二重結合を有する一価の有機基か、Ｏ⁻Ｍ^＋で表される基であってかつＭ^＋が炭素炭素不飽和二重結合を有する化合物のイオンであり、ｎは１又は２である。

In the formula (A), R ¹ is a trivalent or tetravalent organic group, R ² is a divalent organic group, R is a monovalent organic group having a carbon-carbon unsaturated double bond or O ⁻ M ⁺ Wherein M ⁺ is a hydrogen ion or an ion of a compound having a carbon-carbon unsaturated double bond, and at least one of R is a monovalent organic group having a carbon-carbon unsaturated double bond Or a group represented by O ⁻ M ⁺ and M ⁺ is an ion of a compound having a carbon-carbon unsaturated double bond, and n is 1 or 2.

式（Ｂ）中、Ｒ^１１及びＲ^１２は、それぞれ独立に、炭素数１〜２０のアルキル基、フェニル基、カルバゾール基又はフルオレニル基である。前記アルキル基、フェニル基、カルバゾール基及びフルオレニル基は置換基を有してもよい。前記カルバゾール基が複数の置換基を有する場合、隣り合う置換基同士は結合して環を形成してもよい。

In Formula (B), R ¹¹ and R ¹² are each independently an alkyl group having 1 to 20 carbon atoms, a phenyl group, a carbazole group, or a fluorenyl group. The alkyl group, phenyl group, carbazole group and fluorenyl group may have a substituent. When the carbazole group has a plurality of substituents, adjacent substituents may be bonded to form a ring.

式（ＢＢ）中、Ｒ^５０は、炭素数１〜２０のアルキル基、１以上のエーテル結合を含む炭素数２〜２０のアルキル基、炭素数１〜１２のアルコキシ基、炭素数１〜４のアルキル基又は１以上のエーテル結合を含む炭素数２〜２０のアルキル基で置換されたフェニル基、フェニル基、ハロゲン原子、炭素数１〜１２のアルケニル基、又はビフェニリル基であり、Ｒ^５１は、式（１１）で表される基、又は上記Ｒ^５０と同じの基であり、Ｒ^５２〜Ｒ^５４は、各々独立に、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基又はハロゲン原子である。

In the formula (BB), R ⁵⁰ is an alkyl group having 1 to 20 carbon atoms, an alkyl group having 2 to 20 carbon atoms including one or more ether bonds, an alkoxy group having 1 to 12 carbon atoms, or an alkyl group having 1 to 4 carbon atoms. R ⁵¹ is a phenyl group, a phenyl group, a halogen atom, an alkenyl group having 1 to 12 carbon atoms, or a biphenylyl group substituted with an alkyl group or an alkyl group having 2 to 20 carbon atoms containing one or more ether bonds. A group represented by the formula (11), or the same group as the above R ^50, and R ^{52 to} R ⁵⁴ are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or It is a halogen atom.

式（１１）中、Ｒ^５５〜Ｒ^５７は、各々独立に、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基又はハロゲン原子である。

Wherein ^{(11), R} 55 ~R ⁵⁷ are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group or a halogen atom having 1 to 12 carbon atoms.

The photosensitive resin composition of this invention can be used suitably for gray scale mask exposure.
Moreover, the photosensitive resin composition of this invention can be used for the interlayer insulation film of the below-mentioned circuit formation board | substrate, or for protective films.

(A) Component (polymer)
In the polymer having the structural unit represented by the formula (A), R ¹ in the formula (A) is a trivalent or tetravalent organic group. This group is generally a residue other than a carboxy group and an acid anhydride group of a tetracarboxylic acid (dianhydride) or tricarboxylic acid (anhydride) used as a raw material, and a group having an aromatic ring such as a benzene ring. Preferably there is. Specifically, the residue of the tetracarboxylic dianhydride mentioned later etc. are mentioned.

R ² in the formula (A) is a divalent organic group. This group is generally a residue of a diamine compound used as a raw material, and specifically includes a residue of a diamine compound described later.

  In the formula (A), n is 1 or 2. When n is 2, a plurality of R may be the same or different.

R in the formula (A) is a monovalent organic group having a carbon-carbon unsaturated double bond, or a group represented by O ⁻ M ⁺ . O ⁻ M ⁺ is a group in which an oxygen atom is ionically bonded to a compound having a hydrogen atom or a carbon-carbon unsaturated double bond (monovalent organic group). At least one R is a monovalent organic group having a carbon-carbon unsaturated double bond, or an ion of a compound represented by O ⁻ M ⁺ , wherein M ⁺ has a carbon-carbon unsaturated double bond It is.

  Examples of the monovalent organic group or compound having a carbon-carbon unsaturated double bond include monovalent organic groups or compounds containing acryloyl group, methacryloyl group, allyl group, etc. A monovalent organic group or compound containing an acryloyl group or a methacryloyl group is preferred.

Specific examples of R include an acryloxyalkyloxy group (CH ₂ ═CH—COO—R′—O—) and a methacryloxyalkyloxy group (CH ₂ ═C (CH ₃ ) —COO—R′—O—). , acryloxyalkyl amino group _{(CH 2 = CH-COO-} R'-NH-), methacryloxy alkyl amino group _{(CH 2 = C (CH 3} ) -COO-R'-NH-) monovalent such as an organic Groups. R ′ includes an alkylene group (for example, having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms).

The compound having a carbon-carbon unsaturated double bond preferably forms an ester bond with adjacent CO by a covalent bond. In order for a compound having a carbon-carbon unsaturated double bond to form an ester bond with an adjacent carbonyl group, for example, an alcohol having a carbon-carbon unsaturated double bond and a tetracarboxylic acid dicarboxylic acid constituting the acid part of the polymer. React with anhydride.
Also, O compound having a carbon-carbon unsaturated double bond is ionically bound ^- as M ⁺ of the group represented by M ^+, dialkylaminoalkyl acrylates ions or dialkylaminoalkyl methacrylate ion _{(CH 2 = CH-COO-} R _{^{'-N + H (C n H}} 2n + 1) 2, CH 2 = C (CH 3) -COO-R'-n + H (C n H 2n + 1) 2, n are each independently a positive integer (e.g. 1-10, preferably 1-6), and R 'is an alkylene group (for example, C1-10, preferably 1-4)).

  Examples of monovalent organic groups or compound ions having a carbon-carbon unsaturated double bond include, for example, N, N-diethylaminopropyl methacrylate, N, N-dimethylaminopropyl methacrylate, N, N-diethylaminopropyl acrylate, N , N-diethylaminoethyl methacrylate, N, N-dialkylaminoalkyl (meth) acrylate monovalent organic groups or ions, but not limited thereto.

  In component (a), the total amount of the monovalent organic group having a carbon-carbon unsaturated double bond and the ion of the compound is 20 to 200 mol% with respect to 100 mol% of the carboxy group of the polyamic acid. It is preferable.

Among these, at least one of R is preferably a group represented by O ^- M ⁺ in which a compound having a carbon-carbon unsaturated double bond is ion-bonded, from the viewpoint of reactivity and the like. A polymer having a structural unit represented by the formula (1) is preferred.

式（１）中、Ｒ^１、Ｒ^２、Ｍ^＋及びｎは、それぞれ、式（Ａ）のＲ^１、Ｒ^２、Ｍ^＋及びｎと同じである。

Wherein ^{(1), R 1, R} 2, M + and n are respectively the same as ^{R 1, R 2, M +} and n of formula (A).

  The polymer having the structural unit represented by the above formula (A) or (1) is, for example, acryloyl for imparting photosensitivity to polyamic acid obtained by addition polymerization of tetracarboxylic dianhydride and a diamine compound. By adding and stirring an amine compound having a group or a methacryloyl group, the amine compound can be ion-bonded to the polyamic acid. The polymer thus obtained has a structural unit represented by the formula (A) or (1), and has an ion of a compound having an acryloyl group or a methacryloyl group in the polymer.

In the above formula (A) or (1), when m represents the number of structural units represented by [CO—R ¹ —CONH—R ² —NH] (for R ¹ , the side chain group is omitted). Although there is no restriction | limiting in particular, It is preferable that it is m = 30-150. Further, the polymer may have a structural unit other than the structural unit represented by the formula (A) or (1), but is usually represented by the formula (A) or (1). It is preferably composed of structural units and having terminal groups such as hydrogen atoms and OH groups at both ends. As structural units other than the structural unit of the formula (A) or (1), in the formula (A) or (1), a structural unit having no COR or -COO ^- M ⁺ side chain, COR or -COO ^- M Examples include structural units in which all ⁺ are -COOH (carboxy group). The content is preferably t equal to or less than m, where t is the number of structural units other than the structural unit of formula (A) or (1), and t is 0 with respect to the sum of m + t. .3 or less is preferable.

The weight average molecular weight (Mw) of the component (a) is preferably about 10,000 to 200,000. When the component (a) contains O ⁻ M ⁺ , the weight average molecular weight (Mw) in the state before the compound having a carbon-carbon unsaturated double bond is bonded by an ionic bond, that is, in the state of polyamic acid is 10, It is preferable that it is 000-90,000, and it is more preferable that it is 20,000-60,000. Mw can be measured by gel permeation chromatography and calculated in terms of standard polystyrene.

  Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Acid dianhydride, 4,4′-oxydiphthalic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 4, Examples thereof include, but are not limited to, 4′-sulfonyldiphthalic dianhydride and 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride.

  Examples of the diamine compound include p-phenylenediamine, m-phenylenediamine, 2,2′-dimethyl-4,4′-diaminobiphenyl, p-xylylenediamine, m-xylylenediamine, 1,5-diamino. Naphthalene, benzidine, 3,3′-dimethoxybenzidine, 4,4 ′-(or 3,4′-, 3,3′-, 2,4 ′-) diaminodiphenylmethane, 4,4 ′-(or 3,4) '-, 3,3'-, 2,4'-) diaminodiphenyl ether, 4,4'- (or 3,4'-, 3,3'-, 2,4 '-) diaminodiphenyl sulfone, 4,4 '-(Or 3,4'-, 3,3'-, 2,4'-) diaminodiphenyl sulfide, 4,4'-benzophenone diamine, 3,3'-benzophenone diamine, 4,4'-di (4 -Ami Phenoxy) phenylsulfone, 4,4′-bis (4-aminophenoxy) biphenyl, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,1,1 , 3,3,3-hexafluoro-2,2-bis (4-aminophenyl) propane, 2,2'-bis (trifluoromethyl) benzidine, 2,2-bis [4- (4-aminophenoxy) Phenyl] propane, 3,3-dimethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylmethane, 4,4′-di (3-aminophenoxy) ) Phenyl sulfone, 3,3′-diaminodiphenyl sulfone, 2,2′-bis (4-aminophenyl) propane, 5,5′-methylene-bis- (ant) Nilic acid), 3,5-diaminobenzoic acid, 3,3′-dihydroxy-4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4 , 4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminobiphenyl-6,6′-disulfonic acid and other aromatic diamines, 2,6-diaminopyridine, 2,4-diaminopyridine, 2 , 4-diamino-s-triazine, 2,7-diaminobenzofuran, 2,7-diaminocarbazole, 3,7-diaminophenothiazine, 2,5-diamino-1,3,4-thiadiazole, 2,4-diamino- Heterocyclic diamines such as 6-phenyl-s-triazine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, 2,2-dimethylpropylene Examples thereof include aliphatic diamines such as range amine, diaminopolysiloxane represented by the following formula (5), and the like, but are not limited thereto.

式（５）中、Ｒ^６は、各々独立に炭素数１〜６のアルキル基を示し、ｏは、各々独立に１〜１０の整数である。

In formula (5), each R ⁶ independently represents an alkyl group having 1 to 6 carbon atoms, and o is each independently an integer of 1 to 10.

  Said tetracarboxylic dianhydride etc. and a diamine compound are used individually or in combination of 2 or more types, respectively.

In the above formula (A) or (1), when R ² is a structure represented by the following formula (2) or (3), in addition to providing transparency suitable as a photosensitive resin, In order to give low thermal expansibility and low hygroscopic expansibility suitable for use as a protective film, it is preferable.

式（２），（３）中、複数あるＲ^４は、各々独立に、フッ素原子、又は酸素原子、硫黄原子若しくはハロゲン原子を有していてもよい炭素数１〜１０の１価の有機基を表す。ｓ、ｔ及びuは各々独立に０〜４の整数（好ましくは０〜１）を表す。

In formulas (2) and (3), a plurality of R ⁴ are each independently a fluorine atom, or a monovalent organic group having 1 to 10 carbon atoms which may have an oxygen atom, a sulfur atom or a halogen atom. Represents. s, t and u each independently represents an integer of 0 to 4 (preferably 0 to 1).

Among these, R ⁴ is preferably a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluorinated alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a fluorine atom, A group or atom selected from the group consisting of trifluoromethyl groups is more preferable from the viewpoint of low hygroscopic expansion. Particularly preferably R ⁴ is a fluorine atom or a trifluoromethyl group.

Moreover, in Formula (2), it is preferable that two R < ⁴ > is located in the ortho position with respect to the bond which connects both benzene rings at the point of giving low thermal expansibility and low hygroscopic expansibility. Among such structures, a structure in which R ² is represented by the following formula (4) is preferable.

式（４）中、Ｒ^５は各々独立にフッ素原子又はトリフルオロメチル基である。

In formula (4), each R ⁵ is independently a fluorine atom or a trifluoromethyl group.

Component (b) The component (b) is a compound that generates radicals upon irradiation with actinic rays. The photosensitive resin composition of this invention contains the compound represented by the compound represented by the said Formula (B), and a formula (BB) as (b) component.

R ¹¹ and R ^{12 in} the formula (B) are each independently an alkyl group having 1 to 20 carbon atoms (preferably 1 to 10, more preferably 1 to 8), a phenyl group, a carbazole group, or a fluorenyl group, A methyl group, a phenyl group, and a carbazole group are preferable.
Examples of the substituent (hereinafter, also referred to as an optional substituent) that the alkyl group having 1 to 20 carbon atoms, the phenyl group, the carbazole group, or the fluorenyl group of R ¹¹ and R ¹² may have include a nitro group and a halogenated ( Preferably an alkoxy group having 1 to 20 carbon atoms (preferably 1 to 10, more preferably 1 to 8) which may be fluorinated, and 1 to 20 carbon atoms which may be halogenated (preferably fluorinated). Preferably the alkyl group of 1-10, More preferably 1-8), group represented by Formula (8), etc. are mentioned.

式（８）中、Ｒ^２１は、それぞれ独立に、１価の有機基である。ｐは０〜５（１〜３が好ましい）の整数である。
Ｒ^２１の一価の有機基としては、炭素数１〜２０（好ましくは１〜１０、より好ましくは１〜８）のアルキル基又は炭素数１〜２０（好ましくは１〜１０、より好ましくは１〜８）のアルコキシ基、（２，２−ジメチル−１，３−ジオキソラン−４−イル）メトキシ基等が挙げられる。

In formula (8), R ²¹ is each independently a monovalent organic group. p is an integer of 0 to 5 (preferably 1 to 3).
The monovalent organic group for R ²¹ is an alkyl group having 1 to 20 carbon atoms (preferably 1 to 10, more preferably 1 to 8) or 1 to 20 carbon atoms (preferably 1 to 10, more preferably 1 carbon atoms). -8) alkoxy group, (2,2-dimethyl-1,3-dioxolan-4-yl) methoxy group and the like.

In addition, as a substituent that the alkyl group having 1 to 20 carbon atoms, the phenyl group, the carbazole group, or the fluorenyl group of R ¹¹ and R ¹² may have, CH ₃ C (═O) —O—N═C (R ¹¹ )-May be used. R ¹¹ is the same as R ^{11 in the} formula (B).

Examples of the alkyl group having 1 to 20 carbon atoms of R ¹¹ , R ¹² , R ²¹ and an optional substituent include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an n-hexyl group, 2 -Methyl-1-hexyl group, n-heptyl group, n-decyl group, n-dodecyl group and the like.
Examples of R ¹¹ , R ¹² , R ²¹ and an optional substituent having 1 to 20 carbon atoms include groups in which an oxygen atom is bonded to the alkyl group having 1 to 20 carbon atoms.

  When the carbazole group has a plurality of substituents, the ring formed by bonding adjacent substituents is preferably a benzene ring.

  The compound represented by the formula (B) is preferably a compound represented by the following formula (6) or (7) from the viewpoint of achieving both a gamma value and a sensitivity for producing a step shape. The gamma value represents the height of contrast. The larger the gamma value, the higher the contrast. Further, the process tolerance increases as the gamma value decreases. Therefore, in the photosensitive resin composition of this invention, it is preferable to make a gamma value into an appropriate range.

In formulas (6) and (7), R ¹¹ is the same as R ^{11 in} formula (B).
R ^{14 to} R ²⁰ are each independently a hydrogen atom, —NO ₂ group or a group represented by the formula (8). X is C (R ³ ) ₂ or NR ³ .
R ³ is each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Examples of the alkyl group having 1 to 20 carbon atoms of R ³ include those similar to the alkyl group having 1 to 20 carbon atoms of R ¹¹ and R ¹² , and include an ethyl group, an n-propyl group, and 2-methyl-1-hexyl. Groups are preferred.

The photosensitive resin composition of the present invention includes a compound represented by the formula (B) as the component (b), so that the sensitivity is excellent, and R ² is a structure represented by the formula (2) or (3). In the case of the component (a), particularly the component (a) in which R ² is a structure represented by the formula (4), a remarkably good pattern can be given.
Particularly in the case of the component (a) in which R ² is a structure represented by the formula (4), good photosensitivity characteristics are often not obtained and gray scale mask exposure may not be supported. Even so, by including the compound represented by the formula (B), good sensitivity and remaining film ratio can be obtained, and a step shape can be produced. Among them, particularly preferable compounds represented by the formula (B) are compounds represented by the following formulas (B-3) to (B-7).

  The photosensitive resin composition of the present invention is particularly suitable for use as a protective film for a suspension for a hard disk drive, but it is extremely preferable that the function of not increasing the hygroscopic expansion coefficient and sometimes further decreasing it is a formula (B -3).

R ^{50 in the} formula (BB) is an alkyl group having 1 to 20 carbon atoms, an alkyl group having 2 to 20 carbon atoms (preferably 2 to 10 and more preferably 2 to 8 carbon atoms) including one or more ether bonds, carbon number 1 to 12 (preferably 1 to 8) alkoxy group, C1 to C4 alkyl group or C2 to C20 (preferably 2 to 10, more preferably 2 to 8) containing one or more ether bonds A phenyl group substituted with an alkyl group, a phenyl group, a halogen atom, an alkenyl group having 1 to 12 carbon atoms (preferably 1 to 8), or a biphenylyl group. A phenyl group and a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms or an alkyl group having 2 to 20 carbon atoms (preferably 2 to 10, more preferably 2 to 8) containing one or more ether bonds, From the viewpoint of photosensitive characteristics, it is preferable.
Examples of the alkyl group having 1 to 20 carbon atoms of R ^{50 in} the formula (BB) are the same as the alkyl groups having 1 to 20 carbon atoms such as R ¹¹ , R ¹² and R ²¹ described above, a cyclopentyl group, a cyclohexyl group, and the like. Is mentioned.
Alkyl group having 2 to 20 carbon atoms containing one or more ether bonds of R ⁵⁰ of formula (BB) is preferably an alkoxyalkyl group having 2 to 20 carbon atoms, for example, methoxymethyl group.
Examples of the alkoxy group having 1 to 12 carbon atoms of R ^{50 in} the formula (BB) include a methoxy group, an ethoxy group, and a propoxy group.
Examples of the phenyl group substituted with an alkyl group having 1 to 4 carbon atoms of R ^{50 in} formula (BB) or an alkyl group having 2 to 20 carbon atoms containing one or more ether bonds include a tolyl group, a methoxymethyloxyphenyl group, and the like Is mentioned.
Examples of the halogen atom of ^{R 50} of formula (BB), include fluorine atom.
The alkenyl group having 1 to 12 carbon atoms ^{R 50} of formula (BB), a vinyl group.

R ^{51 in} formula (BB) is the group represented by formula (11) or the same group as R ⁵⁰ described above. A phenyl group or a group represented by the formula (11) is preferable.

R ^{52 to} R ⁵⁷ in the formula (BB) are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or a halogen atom.
Examples of the alkyl group having 1 to 12 carbon atoms of R ^{52 to} R ^{57 in} the formula (BB) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an n-hexyl group, and 2-methyl- Examples include 1-hexyl group, n-heptyl group, n-decyl group, n-dodecyl group and the like.
Examples of the alkoxy group having 1 to 12 carbon atoms of R ^{52 to} R ⁵⁷ in formula (BB) include the same as the alkoxy group having 1 to 12 carbon atoms in R ⁵⁰ of formula (BB).
Examples of the halogen atom for R ^{52 to} R ^{57 in} the formula (BB) include the same as the halogen atom for R ^{50 in} the formula (BB).

The compound represented by the formula (BB) is represented by the following formula (BB-1) or (BB-2) from the viewpoint that the gamma value does not become too large and an appropriate process tolerance can be provided. A compound is preferred.

It is preferable that content of (b) component is 0.1-20 mass parts with respect to 100 mass parts of (a) component. More preferably, it is 1-15 mass parts, and the most preferable is 2-12 mass parts from a viewpoint of coexistence of a gamma value and a sensitivity.
By being in the above-mentioned range, it is easy to obtain a step shape forming property derived from excellent photosensitivity and excellent mechanical properties of the film.

The content of the compound represented by the formula (B) is preferably 0.05 to 5 parts by mass, more preferably 0.07 to 2 parts by mass with respect to 100 parts by mass of the component (a). 0.1 to 1 part by mass is more preferable.
The content of the compound represented by the formula (BB) is preferably 0.05 to 15 parts by mass, more preferably 1 to 13 parts by mass with respect to 100 parts by mass of the component (a), and 2 to 12 Part by mass is more preferable.

(C) Component (solvent)
In the present invention, a solvent is usually used when synthesizing the polyamic acid. The photosensitive resin composition of the present invention may contain a component (c) (solvent).
Solvents include acetone, methyl ethyl ketone, toluene, chloroform, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, xylene, tetrahydrofuran, Examples include dioxane, N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, dimethyl sulfoxide, ethylene carbonate, propylene carbonate, sulfolane and the like. These organic solvents may be used alone or in combination of two or more.

  (C) It is preferable that content of a component is 100-500 mass parts with respect to 100 mass parts of said (a) component.

  The photosensitive resin composition of the present invention is generally provided in the form of a varnish (in the present invention, the varnish refers to a state in which the component (a) and the component (b) are dissolved or dispersed in the component (c). ). Moreover, you may add a sensitizer, a light-shielding agent, a polymerization inhibitor, a crosslinking agent, a melt | dissolution promoter, a stabilizer, an adhesion assistant, etc. to the photosensitive resin composition as needed.

The photosensitive resin composition of the present invention may contain a polymerization inhibitor in order to improve resolution and stability during storage. Examples of the polymerization inhibitor include radical polymerization inhibitors and radical polymerization inhibitors.
Examples of such radical polymerization inhibitors or radical polymerization inhibitors include p-methoxyphenol, diphenyl-p-benzoquinone, benzoquinone, hydroquinone, pyrogallol, phenothiazine, resorcinol, orthodinitrobenzene, paradinitrobenzene, metadinitrobenzene, phenanthate. Examples include laquinone, N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, cuperone, phenothiazine, 2,5-toluquinone, tannic acid, parabenzylaminophenol, and nitrosamines. You may use these individually or in combination of 2 or more types.

  0.01-30 mass parts is preferable with respect to 100 mass parts of (a) component, and, as for content of a polymerization inhibitor, 0.05-10 mass parts is more preferable. By being within the above range, stability during storage, photosensitivity and mechanical properties can be enhanced.

  As the dissolution accelerator, for example, a sulfonamide derivative is preferable, and examples include benzenesulfonamide, toluenesulfonamide, methoxybenzenesulfonamide, benzenesulfonylanilide, toluenesulfonylanilide, methoxy-toluenesulfonylanilide, acetyl-toluenesulfonylanilide, Toluenesulfonyl-N-methylamide, toluenesulfonyl-N-ethylamide, toluenesulfonyl-N-propylamide, toluenesulfonyl-N-butyramide, toluenesulfonyl-N-phenylamide, toluenesulfonyl-N-dimethylamide, toluenesulfonyl-N- Examples include diethylamide and toluenesulfonyl-N-diphenylamide. Of these, N-phenylbenzenesulfonamide is preferred because it is particularly effective.

2-30 mass parts is preferable with respect to 100 mass parts of said (a) component, and, as for the addition amount of a solubility promoter, More preferably, it is 3-15 mass parts.
By being within the above range, the photosensitive resin can be satisfactorily dissolved in the developer and a strong pattern can be easily formed.

  Except for the component (c), the photosensitive resin composition of the present invention contains, for example, 75% by mass or more, 85% by mass or more, 95% by mass or more, 98% by mass or 100% by mass, the component (a), You may consist only of the compound represented by the compound represented by Formula (B), and Formula (BB). In addition to these components, the photosensitive resin composition of the present invention can contain substances such as the above-described additives that do not substantially impair the novel and basic characteristics of the present invention.

  The cured product of the photosensitive resin composition of the present invention can be used for an interlayer insulating film and a protective film of a circuit forming substrate. The cured product may be a patterned cured product in which a pattern is formed, or may be a cured product in which a pattern is not formed.

  The pattern forming method of the present invention includes a step of coating the photosensitive resin composition described above on a substrate and drying to form a photosensitive resin film, a step of exposing the photosensitive resin film, and a resin after exposure. A step of developing the film, and a step of heat-treating the resin film after development.

Examples of the coating method include a spray method, a screen printing method, and a spin coating method.
Examples of the substrate include a support substrate for a suspension for a hard disk drive, such as a stainless steel substrate for suspension formation. The substrate may be either before circuit formation or after circuit formation.
Drying is not particularly limited, and can be performed by heating using a known method. By drying, the organic solvent in the photosensitive resin composition is removed, and a photosensitive resin film that is a non-adhesive coating film can be obtained.

The exposure is performed by irradiating the photosensitive resin film with actinic rays in a pattern. For example, a latent image of a through hole pattern is formed. Examples of actinic rays to be irradiated include ultraviolet rays, far ultraviolet rays, visible rays, electron beams, and X-rays.
After irradiation with actinic rays, a desired relief pattern can be obtained by removing unirradiated portions with an appropriate developer.

  The developer is not particularly limited, but is a flame retardant solvent such as 1,1,1-trichloroethane, an aqueous alkali solution such as an aqueous sodium carbonate solution and an aqueous tetramethylammonium hydroxide solution, N, N-dimethylformamide, dimethyl sulfoxide, Good solvents such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and γ-butyrolactone, mixed solvents of these good solvents and poor solvents such as lower alcohols, water, and aromatic hydrocarbons are used. After development, rinsing with a poor solvent or the like may be performed as necessary.

  By heating the relief pattern thus obtained at 80 to 400 ° C. for 5 to 300 minutes, for example, the polyimide precursor is subjected to a cyclization reaction to obtain polyimide, and a pattern cured product can be obtained.

  The pattern forming method of the present invention reduces the manufacturing cost because the photosensitive resin film has an appropriate gamma value while maintaining good sensitivity, and thus can cope with gray scale mask exposure and contribute to process saving. Can be made.

  Next, as an example of the pattern forming method of the present invention, a process of forming a pattern on a hard disk drive suspension will be described with reference to the drawings.

  11 to 20 are schematic cross-sectional views illustrating a conventional process for forming a pattern having a step shape by providing two polyimide resin layers. 1 to 10, for example, a stainless steel foil is prepared as a support substrate 1 constituting the suspension (FIG. 11). Next, a conventional photosensitive resin composition is applied onto the support substrate 1 with a spin coater or the like. The insulating layer (polyimide resin layer) 2 is formed by applying, exposing, developing, and curing (FIG. 12).

  Next, a conventional photosensitive resin composition is applied onto the insulating layer 2 using a spin coater or the like (FIG. 13) and exposed, developed, and cured, as described above, and then the insulating layer (polyimide resin) is applied. Layer) 3 and a step is formed (FIG. 14).

  Next, in order to grow a plating film on the insulating layers 2 and 3 which are insulators, a seed layer 4 is formed as a metal layer as a base (FIG. 15). As the seed layer 4, two layers of a chromium thin film and a copper thin film can be formed by a high frequency sputtering method or the like. Next, a resist 5 is applied on the seed layer 4, and exposure and development are performed in a predetermined pattern (FIG. 16). A circuit having a multilayer structure such as copper, nickel, gold, etc. is sequentially formed on the opening of the resist pattern by electrolytic plating. The circuit 6 is formed by laminating conductors (FIG. 17).

After the circuit 6 is formed, the resist 5 is removed and the seed layer 4 is removed by etching (FIG. 18). Next, in order to protect the circuit 6, the same conventional photosensitive resin composition as described above is applied onto the circuit 6, and exposed and developed to form the protective layer 7 (FIG. 19). Thereafter, a cover 8 that covers a predetermined portion of the protective layer 7 and the support substrate 1 is provided to form a gimbal (FIG. 20).

  On the other hand, FIGS. 1-9 is a schematic sectional drawing explaining the process of forming a level | step difference shape with a gray scale mask using the photosensitive resin composition concerning one Embodiment of this invention. For example, a stainless steel foil is prepared as the support substrate 1 constituting the suspension (FIG. 1), and the above-described photosensitive resin composition of the present invention is applied onto the support substrate 1 using a spin coater or the like (FIG. 2). Then, after exposure through a gray scale mask, development and curing are performed to form an insulating layer (patterned cured product) 2 having a stepped shape (FIG. 3). After forming a seed layer on the stepped insulating layer 2 (FIG. 4), a resist layer 5 is applied, exposed and developed in a predetermined pattern (FIG. 5), and then copper, nickel, etc. by electrolytic plating or the like. Then, the circuit 6 is formed by laminating circuit conductors having a multilayer structure of gold (FIG. 6).

  After the circuit 6 is formed, the resist 4 is removed (FIG. 7), and the seed layer 4 is removed by etching. Next, in order to protect the circuit 6, the same photosensitive resin composition of the present invention as described above is applied onto the circuit 6 and exposed and developed to form the protective layer 7 (FIG. 8). Thereafter, a cover 8 that covers a predetermined portion of the protective layer 7 and the support substrate 1 is provided to form a gimbal (FIG. 9).

  The pattern cured product of the photosensitive resin composition of the present invention can be obtained by the pattern forming method described above.

  5-100 micrometers is preferable, as for the film thickness of the interlayer insulation film and protective film which are the hardened | cured materials of the photosensitive resin composition of this invention, 8-50 micrometers is more preferable, and 5-30 micrometers is more preferable.

The interlayer insulating film is, for example, the insulating layer 2 in FIG. 3 and is formed on a support substrate (metal substrate) such as a stainless steel substrate of a hard disk drive suspension.
The protective film is, for example, the protective layer 7 in FIG. 8, and protects an electrical signal line (circuit 6, conductive layer) formed on, for example, a metal substrate or a resin substrate.

One embodiment of the circuit forming substrate of the present invention has the cured product of the above-described photosensitive resin composition as an interlayer insulating film or a protective film.
Another aspect of the circuit forming substrate of the present invention includes a support substrate, an interlayer insulating film, a conductive layer, and a protective film in this order, and at least one of the interlayer insulating film and the protective film is the photosensitive resin composition described above. It is a cured product. A copper layer may be formed on the interlayer insulating film via a chromium layer or a titanium layer. Both the interlayer insulating film and the protective film are preferably cured products of the photosensitive resin composition.
The circuit formation substrate of the present invention can improve reliability by having a pattern having a good shape and characteristics as an interlayer insulating layer or protective layer of a circuit.

  The circuit forming substrate of the present invention can be used for a suspension for a hard disk drive, a flexible wiring board, and the like.

  FIG. 10 is a schematic plan view showing an example of a suspension of a hard disk drive in which a pattern is formed using the photosensitive resin composition of the present invention. In FIG. 10, a suspension 10 is a member that mounts a magnetic head having a function of writing and reading data on a magnetic disk and accurately controls the gap between the magnetic disk and the magnetic head to several tens of nm. It is comprised from the plate-shaped member 11 manufactured by. A gimbal 13 is integrally formed by a notch 12 at the tip of the plate-like member 11 constituting the suspension 10, and a slider (not shown) having a magnetic head is fixed on the gimbal 13.

  In addition, an insulating layer (not shown) made from the photosensitive resin composition of the present invention is formed on the plate-like member 11, and a predetermined pattern circuit made of the copper conductor layer 14 is mounted thereon. Furthermore, a protective film 15 made from the photosensitive resin composition of the present invention is formed thereon. Since a predetermined pattern circuit is mounted on the plate-like member 11, the suspension 10 is called a so-called “suspension with circuit”.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these Examples.

Synthesis Example 1 (Synthesis of polyamic acid)
After adding 5.4 g (50 mmol) of p-phenylenediamine and 16.0 g (50 mmol) of 2,2′-bis (trifluoromethyl) benzidine to 150 ml of N-methyl-2-pyrrolidone, ', 4,4'-biphenyltetracarboxylic dianhydride 29.4 g (100 mmol) was added and polymerized to obtain a polyamic acid solution.
About the polyamic acid of the obtained polyamic-acid solution, the weight average molecular weight was calculated | required on condition of the following by standard polystyrene conversion using the gel permeation chromatograph (GPC) method. The polyamic acid had a weight average molecular weight of 41,400.

The measurement was performed using a solution of 1 ml of a solvent [tetrahydrofuran (THF) / dimethylformamide (DMF) = 1/1 (volume ratio)] with respect to 0.5 mg of polyamic acid.
Measuring device: Detector L4000 UV manufactured by Hitachi, Ltd.
Pump: L6000 manufactured by Hitachi, Ltd.
C-R4A Chromatopac manufactured by Shimadzu Corporation
Measurement conditions: Column Gelpack GL-S300MDT-5 × 2 eluent: THF / DMF = 1/1 (volume ratio)
LiBr (0.03 mol / l), H ₃ PO ₄ (0.06 mol / l)
Flow rate: 1.0 ml / min, detector: UV 270 nm

  N, N-dimethylaminopropyl methacrylate was added to the polyamic acid solution in a molar equivalent with the carboxy group of the amic acid used, and stirred for 60 minutes to obtain a polymer I solution.

Examples 1-8 and Comparative Examples 1-8
1. Preparation of photosensitive resin composition A predetermined amount of the photosensitive agent shown in Table 1 was added to the polymer I solution and stirred to obtain a photosensitive resin solution. The numerical values of the photosensitizers in Table 1 are parts by mass of the photosensitizer when the mass of the polymer I is 100. In addition, each component used is as follows.

Polymer Polymer I (component (a)): Polymer I obtained in Synthesis Example 1

Photosensitizer b-1 (component (b)): DAROCUR TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, compound having the structure of the following formula (b-1)) manufactured by BASF
b-2 (component (b)): Irgacure 819 manufactured by BASF (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, a compound having the structure of the following formula (b-2))
b-3 (component (b)): Compound having the structure of the following formula (b-3) b-4 (component (b)): ADEKA OPTOMETER N-1919 (made by ADEKA Corporation) (following formula (b-4)) Compound having the structure of
b-5 (component (b)): IRGACURE OXE-02 (etanone-1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] -1- (o-) manufactured by BASF Acetyloxime), a compound having the structure of the following formula (b-5))
b-6 (component (b)): DFI-020 (a compound having the structure of the following formula (b-6)) manufactured by Daito Chemix Co., Ltd.
b-7 (component (b)): Adeka Cruz NCI-831 manufactured by ADEKA Corporation (compound having the structure of the following formula (b-7))
b-8: IRGACURE OXE-01 (1,2-octanedione, 1- [4- (phenylthio) phenyl] -2- (O-benzoyloxime) manufactured by BASF, having the structure of the following formula (b-8) Compound)

2. Evaluation of remaining film ratio and step shape moldability The obtained photosensitive resin composition was spin-coated on a silicon substrate and dried on a hot plate at 90 ° C. for 3 minutes to obtain a photosensitive resin film having a thickness of 12 μm. It was. This photosensitive resin layer through a photomask, was exposed for 500 mJ / cm ² or 100 mJ / cm ² by a high pressure mercury lamp. Thereafter, immediately after heating at 110 ° C. for 1 minute on a hot plate, the sample was immersed in a developer solution using an organic solvent (dimethyl sulfoxide / γ-butyrolactone / water = 41/51/8 (mass ratio)), and the unexposed portion was removed. Dissolved.

After the unexposed portion was completely dissolved, the substrate was taken out from the developer, rinsed with isopropyl alcohol, and then the film thickness after development was measured.
The remaining film ratio was calculated by dividing the obtained film thickness after development by the film thickness before exposure (12 μm).

The remaining film rate when irradiated with 500 mJ / cm ² was evaluated as follows.
70% or more: A
65% or more and less than 70%: B
60% or more and less than 65%: C
Less than 60%: D

The remaining film rate when irradiated with 100 mJ / cm ² was evaluated as follows.
20% or more and less than 50%: A
50% or more and less than 60%: B
60% or more and less than 70%: C
Less than 20% or 70% or more: D
Also, when the pattern was peeled off after development, it was evaluated as D.

The step shape forming property was calculated by dividing the remaining film rate when irradiated with 500 mJ / cm ² by the remaining film rate when irradiated with 100 mJ / cm ² .
As the difference between the remaining film rate at the low exposure amount and the remaining film rate at the high exposure amount is larger, the step shape forming property is higher. Therefore, the evaluation was performed as follows.
1.6 or higher: A
1.3 or more and less than 1.6: B
1.1 or more and less than 1.3: C
Less than 1.1: D

  In the said Examples 1-8, the board | substrate after the remaining film rate measurement was heated in 375 degreeC 60 minute (s) oven, and the pattern cured film was obtained. All were good pattern cured films.

  The photosensitive resin composition of the present invention can be used for suspensions for hard disk drives. The hard disk suspension of the present invention can be used for a hard disk or the like.

Although several embodiments or examples of the present invention have been described in detail above, those skilled in the art will recognize many examples or examples without departing from the novel teachings and advantages of the present invention. It is easy to make changes. Accordingly, many of these modifications are within the scope of the present invention.
The entire contents of the documents described in this specification are incorporated herein by reference.

Claims (15)

(A) A polymer having a structural unit represented by the following formula (A), and (b) a compound represented by the following formula (B) and a compound represented by the following formula (BB) as a compound that generates radicals upon irradiation with actinic rays. The photosensitive resin composition containing the compound made.

(In formula (A), R ¹ is a trivalent or tetravalent organic group, R ² is a divalent organic group, R is a monovalent organic group having a carbon-carbon unsaturated double bond, or O ⁻ M ^+. M ⁺ is a hydrogen ion or an ion of a compound having a carbon-carbon unsaturated double bond, and at least one of R is a monovalent organic compound having a carbon-carbon unsaturated double bond. Or a group represented by O ⁻ M ⁺ and M ⁺ is an ion of a compound having a carbon-carbon unsaturated double bond, and n is 1 or 2.)

(In the formula (B), R ¹¹ and R ¹² are each independently an alkyl group having 1 to 20 carbon atoms, a phenyl group, a carbazole group, or a fluorenyl group. The alkyl group, phenyl group, carbazole group, and fluorenyl group. (In the case where the carbazole group has a plurality of substituents, adjacent substituents may be bonded to form a ring.)

(In the formula (BB), R ⁵⁰ represents an alkyl group having 1 to 20 carbon atoms, an alkyl group having 2 to 20 carbon atoms including one or more ether bonds, an alkoxy group having 1 to 12 carbon atoms, or 1 to 4 carbon atoms. Or a phenyl group, a phenyl group, a halogen atom, an alkenyl group having 1 to 12 carbon atoms, or a biphenylyl group substituted with an alkyl group having 2 to 20 carbon atoms containing one or more ether bonds, and R ⁵¹ is , A group represented by formula (11), or the same group as R ⁵⁰ described above, and R ^{52 to} R ⁵⁴ are each independently an alkyl group having 1 to 12 carbon atoms and an alkoxy group having 1 to 12 carbon atoms. Or a halogen atom.)

(In the formula ^(11), R 55 ^{to R 57} each independently represent an alkyl group having 1 to 12 carbon atoms, an alkoxy group or a halogen atom having 1 to 12 carbon atoms.) The photosensitive resin composition according to claim 1, wherein the component (a) is a polymer having a structural unit represented by the following formula (1).

(In the formula ^{(1), R 1, R} 2, M + and n are each the same as ^{R 1, R 2, M +} and n in the formula (A).) The photosensitive resin composition according to claim 1 or 2, wherein R ² has a structure represented by the following formula (2) or (3).

(In the formulas (2) and (3), a plurality of R ⁴ are each independently a monovalent organic compound having 1 to 10 carbon atoms which may have a fluorine atom, an oxygen atom, a sulfur atom or a halogen atom. S, t and u each independently represents an integer of 0 to 4) The photosensitive resin composition according to claim 1, wherein R ² has a structure represented by the following formula (4).

(In Formula (4), each R ⁵ is independently a fluorine atom or a trifluoromethyl group.) The photosensitive resin composition according to any one of claims 1 to 4, wherein the compound represented by the formula (B) is a compound represented by the following formula (6) or (7).

(In the formulas (6) and (7), R ¹¹ is the same as R ^{11 in the} formula (B). R ^{14 to} R ²⁰ are each independently a hydrogen atom, —NO ₂ group or the following formula (8). X is C (R ³ ) ₂ or NR ^3. Each R ³ is independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.)

(R ²¹ is each independently a monovalent organic group. P is an integer of 0 to 5) The photosensitive resin composition according to any one of claims 1 to 4, wherein the compound represented by the formula (B) is any one of compounds represented by the following formulas (B-3) to (B-7). object.

The photosensitive resin composition according to any one of claims 1 to 6, wherein the compound represented by the formula (BB) is a compound represented by the following formula (BB-1) or (BB-2).

  Content of the said (b) component is 0.1-20 mass parts with respect to 100 mass parts of said (a) component, The photosensitive resin composition in any one of Claims 1-7.   The photosensitive resin composition according to claim 1, which is used for a hard disk drive suspension.   The photosensitive resin composition according to claim 1, which is for gray scale mask exposure. Applying the photosensitive resin composition according to any one of claims 1 to 10 on a substrate and drying to form a photosensitive resin film;
Exposing the photosensitive resin film;
Developing the resin film after exposure;
And a step of heat-treating the resin film after development.   Hardened | cured material of the photosensitive resin composition in any one of Claims 1-10.   The circuit formation board which has the hardened | cured material of Claim 12 as an interlayer insulation film or a protective film. Including a support substrate, an interlayer insulating film, a conductive layer, and a protective film in this order,
The circuit forming substrate according to claim 12, wherein at least one of the interlayer insulating film and the protective film is a cured product.   A hard disk drive suspension comprising the circuit forming substrate according to claim 13.

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