JP5644068B2 - Photosensitive resin composition, method for producing resist pattern, and hard disk suspension - Google Patents

Description

  The present invention relates to a photosensitive resin composition, a method for producing a resist pattern, and a hard disk suspension using the same.

  Among existing organic polymers, aromatic polyimides with the highest heat resistance are flexible printed wiring boards (FPC), tape automated bonding (TAB), chip-on-film (COF) and semiconductor chips because of their solder heat resistance. Used as a buffer coat film and an interlayer insulating film. Since most of the uses of polyimide are in the microelectronics field as described above, the heat resistance is almost sufficient at present, except for special applications such as the aerospace field. There is a feeling that research that aims to be almost complete.

  At present, it can be said that the correlation between physical heat resistance (such as glass transition temperature) and chemical heat resistance (such as thermal oxidation stability) and the chemical structure of polyimide has been largely elucidated. The current trend of heat resistant polymer research is how to achieve the characteristics required for each application while maintaining heat resistance. Recently, polyimide or polyimide resin composition has been required to have higher dimensional stability in flexible printed circuit board (FPC) and tape automated bonding (TAB) applications. In addition to low CTE, low hygroscopic expansion coefficient (CHE) has become necessary (for example, Patent Documents 1 to 5).

  In addition, polyimide is used as the interlayer insulating film of the semiconductor chip. In order to prevent a decrease in the signal propagation speed in the wiring layer, the insulating layer is required to have a low dielectric constant and a low dielectric loss tangent, which further reduces thermal stress. From the viewpoint, low CTE and low water absorption are also required from the viewpoint of device reliability. Moreover, when forming a polyimide insulating layer, high temperature like a thermal imidation process may not be applied, and it is sometimes calculated | required that polyimide itself is soluble in an organic solvent.

  However, molecular designs that increase the solubility of polyimide often have undesirable effects, such as a decrease in Tg and an increase in CTE. Polyimide is used as a buffer coat film for protecting semiconductor chip circuits and inorganic passivation films from external stress. Such polyimide has heat resistance, high elastic modulus, low thermal expansion coefficient, and low water absorption. In addition, micro-drilling workability, i.e. photosensitivity, for connection to external electronic circuits is required. Although positive photosensitive polyimide capable of alkali development is desirable from the viewpoint of the environment, currently known positive photosensitive polyimide is not sufficient in terms of resolution.

  As a current positive photosensitive heat-resistant material, photosensitive polybenzoxazole is superior to photosensitive polyimide in terms of higher resolution, but currently known polybenzoxazoles satisfy all of the above required characteristics. It is difficult to do this at present (for example, Patent Documents 6 to 10).

  The development of positive photosensitive polyimide that can achieve a resolution of 3 μm and in the future 1 μm while maintaining all of the above required characteristics is expected. As another semiconductor insulating film, a heat-resistant polymer material having low CTE and low elastic modulus at the same time is required.

With the spread of digital home appliances in recent years and higher performance, polyimide, which has the highest heat resistance among organic polymers, uses its good thermal, mechanical, and electrical properties, and is positioned as a substrate material for silicon. Is immovable. Recently, the use of polyimide is not limited only to the substrate material, and various applications to the substrate have been studied, and improvement by the constituent materials is also active.

  For example, in the fields of personal computers and hard disks, polyimide has been used for suspensions thereof. In an HDD used for a hard disk recorder or the like, a magnetic head for reading a record from a magnetic disk is incorporated at the tip of a suspension component. The gap between the magnetic disk and the magnetic head is required to be constant at 0.01 μm (tens of nm), which corresponds to the accuracy with which a jumbo jet can fly below 1 mm above the ground. This suspension part is made of thin stainless steel foil. The polyimide resin used in the suspension portion that requires high accuracy is desired to have a lower hygroscopic expansion coefficient (for example, Patent Documents 11 and 12).

Japanese Patent No. 3712164 JP 2006-173655 A JP 2008-1876 A JP 2008-1877 A Japanese Patent Laid-Open No. 10-36506 Japanese Patent Laid-Open No. 2000-159887 JP 2000-290372 A JP 2006-328407 A Japanese Patent No. 3860359 JP 2006-328407 A JP 2008-251121 A JP 2008-310946 A

  However, at present, polyimides with higher hygroscopic expansion than stainless steel foil or the same type are available, and those with lower hygroscopic expansion coefficients have been required for the next generation large capacity HDD / high capacity communication era. Yes.

  An object of the present invention is to provide a photosensitive resin composition for a hard disk suspension protective film having a sufficiently low hygroscopic expansion coefficient, a method for producing a resist pattern using the same, and a hard disk suspension.

［式（１）中、Ａｒはエーテル基及びカルボニル基を有さない４価の有機基を示し、Ｒはエーテル基及びカルボニル基を有さない２価の有機基を示し、ｎは１以上の整数を示す。］ The present invention provides (A) a polyimide resin having a structure represented by the following general formula (1) or a precursor thereof, (B) a crosslinking agent, and (C) a photosensitive property for a hard disk suspension protective film including an initiator. A resin composition is provided.

[In the formula (1), Ar represents a tetravalent organic group not having an ether group and a carbonyl group, R represents a divalent organic group not having an ether group and a carbonyl group, and n is 1 or more. Indicates an integer. ]

で表される群から選択される４価の有機基を有することが好ましく、上記Ｒは、

［式中、ｍ，ｌ，ｎ，ｊ及びｋは１〜１０の整数を示し、ｈ及びｉは０〜１０の整数を示す。］
で表される群より選ばれる少なくとも１種の２価の有機基であることが好ましい。 Ar is

It is preferable to have a tetravalent organic group selected from the group represented by:

[Wherein, m, l, n, j and k represent integers of 1 to 10, and h and i represent integers of 0 to 10. ]
It is preferably at least one divalent organic group selected from the group represented by:

The hydrophilic parameter of the component (A) is preferably -7 to -3. The “hydrophilic parameter” means P (hydrophilicity) defined by the following formulas (3) and (4).

[Where a _i is the amount of acid dianhydride (parts by mass), E _i is the value obtained by theoretical calculation (Gaussiann program: HF / 6-31G) of the hydration energy of the model molecule and water shown below ( kJ / mol), MW _i is the molecular weight of the model molecule, bj is the amount of diamine (part by mass), E _j is the theoretical calculation of the model molecule and water hydration energy shown below (Gaussiann program: HF / 6-31G) (MWJ / mol), MW _j represents the molecular weight of the model molecule. ]

  The present invention also provides a method for producing a resist pattern, which comprises a step of applying and drying the photosensitive resin composition of the present invention on a support substrate, a step of exposing, and a step of developing using a developer.

  The present invention further provides a hard disk suspension having a resist pattern obtained by the production method of the present invention as a surface protective film and / or an interlayer insulating film.

  The present invention can provide a photosensitive resin composition having a hygroscopic expansion coefficient of 20 or less after curing, a method for producing a resist pattern using the same, and a hard disk suspension.

It is sectional drawing which shows suitable one Embodiment of the hard-disk suspension of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

<(A) component: polyimide resin>
(A) The polyimide resin represented by the general formula (1) or a precursor thereof (hereinafter also simply referred to as “(A) polyimide resin”) is a tetracarboxylic dianhydride (hereinafter simply referred to as “acid dianhydride”). It can also be synthesized from diamine and diamine by known methods.

  The acid dianhydride corresponds to the Ar portion in the above general formula (1), and does not include an ether bond in the structure, and further does not include a carbonyl group in the portion corresponding to Ar. The acid dianhydride is preferably an aromatic acid dianhydride, and more preferably contains an F atom.

  The diamine corresponds to the R portion of the general formula (1) and does not contain an ether bond or a carbonyl group in its structure. The diamine is preferably an aromatic diamine, and more preferably contains an F atom.

  In addition, regarding these monomers, when the binding energy with water molecules is calculated, it is preferable that the stability is low.

  Examples of aromatic tetracarboxylic dianhydrides that can be used include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyl. Sulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, hydroquinone-bis (trimellitate anhydride) Methylhydroquinone-bis (trimellitate anhydride) bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5- (dioxotetrahydrofuryl-3 -Methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -tetralin-1,2-di Carboxylic acid dianhydride. These can be used alone or in admixture.

  Usable aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodurene, 4,4. '-Diaminodiphenylmethane, 4,4'-methylenebis (2-methylaniline), 4,4'-methylenebis (2-ethylaniline), 4,4'-methylenebis (2,6-dimethylaniline), 4,4' -Methylenebis (2,6-diethylaniline), 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, benzidine, 3,3'-dihydroxybenzidine, o-tolidine, m-tolidine, 2,2 '-Bis (trifluoromethyl) benzidine, 2,2-bis (4-aminophenyl) hexafluoropro , P-terphenylenediamine, 4,4′-methylenebis (cyclohexylamine), isophoronediamine, trans-1,4-diaminocyclohexane, cis-1,4-diaminocyclohexane, 1,4-cyclohexanebis (methylamine) 2,5-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 3,8-bis (aminomethyl) tricyclo [ 5.2.1.0] Decane, 1,3-diaminoadamantane, 2,2-bis (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane, 1,3-propane Diamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenedia Emissions, 1,7 heptamethylene diamine, 1,8-octamethylene diamine, 1,9-nonamethylenediamine, and the like. These can be used individually by 1 type or in combination of 2 or more types.

  The polyimide resin has a structure (repeating unit) represented by the general formula (1).

  The polyimide resin can be synthesized by selecting and combining the above-described tetracarboxylic dianhydride and diamine and reacting them in an organic solvent. Specifically, after the polyimide resin synthesizes polyamic acid (precursor) by addition polymerization of approximately equimolar amounts of tetracarboxylic dianhydride and diamine in an organic solvent at 30 to 80 ° C. for 2 to 3 hours. , 120 ° C or higher, preferably 350 ° C or higher for 1 to 5 hours by dehydration condensation, ring closure and imidization.

  In addition, the present inventors have found that the hydrophilic parameter of the polyimide resin is closely related to the hygroscopic expansion coefficient. Hereinafter, the theoretical calculation of the hydrophilic parameter will be described.

［式中、Ｒ¹は４価の芳香族基を示す。］ <Theoretical calculation>
First, regarding tetracarboxylic dianhydride, the acid dianhydride represented by the following general formula (1a) is replaced with the structure represented by the following formula (1b) in order to unify the theoretical calculation. Made.

[Wherein R ¹ represents a tetravalent aromatic group. ]

  After structural optimization, the stabilization energy when water molecules are coordinated to heteroatoms such as N, O, and S contained in tetracarboxylic dianhydride is obtained by calculation, and the total energy is expressed as Ei. did.

[Ｒ^２は２価の芳香族基を示す] Next, regarding the diamine, the diamine represented by the following general formula (2a) is replaced with the structure represented by the following formula (2b) in order to unify the calculation in the same manner as the tetracarboxylic dianhydride. The structure was optimized.

[R ² represents a divalent aromatic group]

  Next, the stabilization energy when water molecules were coordinated to heteroatoms such as N, O, and S contained in the diamine was determined by calculation, and the sum of the energies was defined as Ej.

The evaluation by the theoretical calculation of hydrophilicity is calculated individually for various tetracarboxylic dianhydrides and diamines using molecular orbital calculation, and the hydrophilicity parameter P (defined by the following formulas (3) and (4) is used. sought as hydrophilicity). In this case, the ratio of each component combined during the synthesis of the precursor is used.

Here, regarding acid dianhydride as a raw material of the polyimide precursor, a _i is the amount of acid dianhydride (part by mass), E _i is the theoretical calculation of the hydration energy of the model molecule and water shown below (Gaussiann program: HF / 6-31G) (kJ / mol), MW _i is the molecular weight of the model molecule.
Furthermore, regarding the diamine that is the raw material of the polyimide precursor, bj is the amount of diamine (part by mass), _Ej is the model molecule and water hydration energy shown below by theoretical calculation (Gaussiann program: HF / 6-31G). The value (kJ / mol), MW _j is the molecular weight of the model molecule.

  The combination of tetracarboxylic dianhydride and diamine is combined at a ratio of 10 parts by mass of tetracarboxylic dianhydride and 10 parts by mass of diamine so that the total amount becomes 20 parts by mass. Moreover, each component may be not only one type but several types may be mixed. In this case, the total of each combination only needs to be 10 parts by mass, and there is no limitation on the ratio and the type of components used.

For example, when 2 parts by weight of tetracarboxylic dianhydride A, 8 parts by weight of tetracarboxylic dianhydride B, 4 parts by weight of diamine C and 6 parts by weight of diamine D are used,
Σ (a _i / MW _i ) + Σ (b _j / MW _i ) = (tetracarboxylic dianhydride A × 2) + (tetracarboxylic dianhydride B × 8) + (diamine C × 4) + (diamine D × 6) = 20
It becomes.

When tetracarboxylic dianhydride and diamine are selected to have a small stabilization energy with water, a photosensitive resin composition having a smaller CHE can be obtained.
Is obtained.

  Next, a method for calculating the stabilization energy (E) by hydration of the monomer will be described taking BTDA represented by the following formula (7a) as an example as an acid dianhydride.

A state in which BTDA is replaced with a model compound as described above and water molecules are coordinated with the model compound is shown in the following formula (7b).

The stabilization energy (Ei) of monomer hydration is calculated for each monomer individually using molecular orbital calculation.
In the case of BTDA, Ei = ε (H ₂ O (1)) × 4 + ε (H ₂ O (2))
It becomes.

Table 1 below shows the structural formulas and model compounds of acid dianhydrides.

Table 2 below shows the stabilization energy (E) due to hydration of the monomer calculated individually for each monomer using molecular orbital calculation and E _i (kJ / mol) / MW _i obtained by dividing the energy by the molecular weight.

Table 3 below shows the structural formula and model compound of diamine.

Table 4 below shows the stabilization energy (E) due to hydration of the monomer calculated individually for each monomer using molecular orbital calculation and E _j (kJ / mol) / MW _j obtained by dividing the energy by the molecular weight.

  Finally, the theoretical calculation value is expressed as the sum of the stabilization energy (E) of each monomer. In this case, the ratio of each component used in the synthesis of the precursor is used.

That is, the hydrophilicity of a polyimide resin comprising a combination of an arbitrary acid anhydride and diamine can be determined as a hydrophilic parameter P (hydrophilicity) shown in Formula (3). That is, tetracarboxylic dianhydride and diamine, tetracarboxylic dianhydride A: 2 parts by mass, tetracarboxylic dianhydride B: 8 parts by mass, diamine C: 4 parts by mass, diamine D: 6 parts by mass When combined at a ratio of, the hydrophilicity parameter P (hydrophilicity) is
P (hydrophilicity) = Σ (a _i E _i / MW _i ) + Σ (b _j E _j / MW _j ) = (Ei (kJ / mol) / MWi × 2 of tetracarboxylic dianhydride A) + (tetra Ei (kJ / mol) / MWi × 8) of carboxylic dianhydride B + (Ej (kJ / mol) / MWj × 4 of diamine C) + (Ej (kJ / mol) / MWj × 6 of diamine D)
It is calculated as follows.

From the viewpoint of reducing the hygroscopic expansion coefficient, the hydrophilic parameter P (hydrophilicity) is preferably −7.0 or more and −3.0 or less.
(A) The weight average molecular weight of the polyimide resin or the precursor thereof is preferably 20000 to 200000, more preferably 30000 to 70000, and more preferably 40000 to 60000, from the viewpoint of further improving the film formability and developability. It is particularly preferred that

  (A) The content of the polyimide resin or its precursor is preferably 40 to 90% by mass, more preferably 45 to 80% by mass, based on the total solid content of the photosensitive resin composition. It is especially preferable that it is 50-70 mass%.

<(B) component: cross-linking agent>
(B) A crosslinking agent will not be specifically limited if it is a compound which has at least 1 ethylenically unsaturated group in a molecule | numerator.

  (B) Examples of the cross-linking agent include N, N-dialkylamino such as N, N-diethylaminopropyl methacrylate, N, N-dimethylaminopropyl methacrylate, N, N-diethylaminopropyl acrylate, and N, N-diethylaminoethyl methacrylate. It is obtained by reacting an α, β-unsaturated carboxylic acid with an alkyl (meth) acrylate (an amine compound having a (meth) acryloyl group), a compound having an amide bond and two or more ethylenically unsaturated groups, and a polyhydric alcohol. Compound, bisphenol A-based (meth) acrylate compound, compound obtained by reacting glycidyl group-containing compound with α, β-unsaturated carboxylic acid, urethane monomer or urethane oligomer such as (meth) acrylate compound having urethane bond, nonyl Phenoxypoly Chi alkyleneoxy acrylate, phthalic acid-based compounds, and (meth) acrylic acid alkyl ester. These are used alone or in combination of two or more.

  In the compound having an amide bond and two or more ethylenically unsaturated groups, the number of amide bonds in the molecule is preferably 2 to 12, and more preferably 4 to 8. In the compound having an amide bond and two or more ethylenically unsaturated groups, the number of ethylenically unsaturated groups in the molecule is preferably 2 to 6. By satisfying these conditions, the compound having an amide bond and two or more ethylenically unsaturated groups tends to improve the balance of compatibility and developability with the precursor (polyamic acid) of (A) polyimide resin. is there. If the number of amide bonds in the molecule is less than 2, the glass transition temperature of the cured product tends to decrease, and if it exceeds 12, the developability tends to decrease. Moreover, there exists a tendency for developability to fall that the number of ethylenically unsaturated groups in a molecule is less than two.

［式（２１）中、Ｒ^１、Ｒ^２及びＲ^３は各々独立に、２価の有機基を示し、Ｒ^４は水素原子又はメチル基を示し、Ｒ^５及びＲ^６は各々独立に、水素原子、炭素数１〜４のアルキル基又はフェニル基を示す。］ The compound having an amide bond and two or more ethylenically unsaturated groups in the molecule is preferably a compound represented by the following general formula (21).

[In formula (21), R ¹ , R ² and R ³ each independently represents a divalent organic group, R ⁴ represents a hydrogen atom or a methyl group, and R ⁵ and R ⁶ each independently represent hydrogen. An atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group is shown. ]

The compound represented by the general formula (21) is a di (meth) acrylate having an amide bond, obtained by reacting an oxazoline group-containing compound with a carboxyl group-containing compound and / or a phenolic hydroxyl group-containing compound. Is preferred. The polymerizable compound represented by the general formula (21) includes, for example, a bisoxazoline represented by the following general formula (17), a compound having two phenolic hydroxyl groups in one molecule, and (meth) acrylic. It can be obtained by reacting with an acid.

In general formula (17), Y represents a divalent organic group, but a phenylene group which may have a substituent, a pyridylene group which may have a substituent, or a branched chain having 1 to 10 carbon atoms. It is preferably an alkylene group which may be used. R ⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group.

  Examples of the bisoxazoline represented by the general formula (17) include 2,2 ′-(1,3-phenylene) bis-2-oxazoline and 2,6-bis (4-isopropyl-2-oxazoline-2). -Yl) pyridine, 2-2'-isopropylidenebis (4-phenyl-2-oxazoline), 2-2'-isopropylidenebis (4-tertiarybutyl-2-oxazoline) and the like. These can be used alone or in combination of two or more.

  Examples of the compound having two phenolic hydroxyl groups in one molecule include biphenol, tetramethylbiphenol, dihydroxynaphthalene, dihydroxymethylnaphthalene, dihydroxydimethylnaphthalene, bis (4-hydroxyphenyl) ketone, bis (4-hydroxy-3, 5-dimethylphenyl) ketone, bis (4-hydroxy-3,5-dichlorophenyl) ketone, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxy-3,5-dimethylphenyl) sulfone, bis (4-hydroxy) -3,5-dichlorophenyl) sulfone, bis (4-hydroxyphenyl) hexafluoropropane, bis (4-hydroxy-3,5-dimethylphenyl) hexafluoropropane, bis (4-hydroxy-3,5-dichlorophenyl) Xafluoropropane, bis (4-hydroxyphenyl) dimethylsilane, bis (4-hydroxy-3,5-dimethylphenyl) dimethylsilane, bis (4-hydroxy-3,5-dichlorophenyl) dimethylsilane, bis (4-hydroxy) Phenyl) methane, bis (4-hydroxy-3,5-dichlorophenyl) methane, bis (4-hydroxy-3,5-dibromophenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, 2,2- Bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-chlorophenyl) propane, bis (4-hydroxy) Phenyl) ether, bis (4-hydroxy-3,5-dimethylphenyl) ether, bis (4-hydroxy-3,5-dichlorophenyl) ether, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9- Bis (4-hydroxy-3-methylphenyl) fluorene, 9,9-bis (4-hydroxy-3-chlorophenyl) fluorene, 9,9-bis (4-hydroxy-3-bromophenyl) fluorene, 9,9- Bis (4-hydroxy-3-fluorophenyl) fluorene, 9,9-bis (4-hydroxy-3-methoxyphenyl) fluorene, 9,9-bis (4-hydroxy-3,5-dimethylphenyl) fluorene, 9 , 9-bis (4-hydroxy-3,5-dichlorophenyl) fluorene, 9,9-bis (4-hydroxy-) 3,5-dibromophenyl) fluorene and the like. Among these, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane is particularly preferable.

  The reaction between the phenolic hydroxyl group-containing compound and / or the carboxyl group-containing compound and the oxazoline group-containing compound is preferably performed at a reaction temperature of 50 to 200 ° C. When the reaction temperature is less than 50 ° C., the reaction is slow, and when the reaction temperature is 200 ° C., many side reactions tend to occur. In some cases, the reaction may be carried out in a polar organic solvent such as dimethylformamide, dimethylacetamide, or dimethylsulfoxide.

  Examples of the compound obtained by reacting the polyhydric alcohol with an α, β-unsaturated carboxylic acid include, for example, polyethylene glycol di (meth) acrylate having 2 to 14 ethylene groups and 2 to 2 propylene groups. 14 polypropylene glycol di (meth) acrylate, polyethylene polypropylene glycol di (meth) acrylate having 2 to 14 ethylene groups and 2 to 14 propylene groups, trimethylolpropane di (meth) acrylate, Trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, EO, PO-modified trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meta) ) Acrylate, tetramethylolmethane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and the like.

  Here, “EO” represents ethylene oxide, and an EO-modified compound represents one having a block structure of an ethylene oxide group. “PO” represents propylene oxide, and a PO-modified compound has a propylene oxide group block structure.

  Examples of the compound obtained by reacting the glycidyl group-containing compound with an α, β-unsaturated carboxylic acid include, for example, an epoxy resin (a) such as a novolac type epoxy resin, a bisphenol type epoxy resin, and a salicylaldehyde type epoxy resin; Examples thereof include an epoxy acrylate compound obtained by reacting (meth) acrylic acid (b). An acid-modified epoxy acrylate compound obtained by reacting an acid anhydride such as tetrahydrophthalic anhydride with the OH group of the epoxy acrylate compound can also be used. As such an acid-modified epoxy acrylate compound, for example, EA-6340 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.) is commercially available.

  As the (meth) acrylate compound having a urethane bond, a (meth) acrylic monomer having an OH group at the β-position, isophorone diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, 1,6-hexamethylene Addition reaction products with diisocyanate compounds such as diisocyanate; EO-modified urethane di (meth) acrylate; EO or PO-modified urethane di (meth) acrylate; carboxyl group-containing urethane (meth) acrylate; diol compound and the like.

  From the viewpoint of further reducing the hygroscopic expansion coefficient (CHE), it is preferable to include a compound having an amide bond and two or more ethylenically unsaturated groups, among these crosslinking agents.

  (B) The content of the crosslinking agent is preferably 5 to 55 mass%, more preferably 10 to 50 mass%, and more preferably 20 to 45 mass% based on the total solid content of the photosensitive resin composition. % Is particularly preferred.

<(C) component: initiator>
The (C) initiator can be used without any particular limitation as long as it generates free radicals with actinic rays.
(C) As initiators, aromatic ketones, acyl phosphine oxides, oxime esters, quinones, benzoin ether compounds, benzyl derivatives, 2,4,5-triarylimidazole dimers, acridine derivatives, N-phenyl Examples include glycine, N-phenylglycine derivatives, coumarin compounds, and titanocene compounds.

  Examples of the aromatic ketone include benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (that is, Michler ketone), N, N′-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4. '-Dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino- Propan-1-one is mentioned.

  Examples of the acylphosphine oxide include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and the like.

Examples of oxime esters include 1,2-octanedione-1- [4- (phenylthio) phenyl] -2- (O-benzoyloxime) represented by the following formula (8) (trade name: Irgacure-OXE- 01 (hereinafter also referred to as Irg-OXE-01), manufactured by Ciba Specialty Chemicals), 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] ethanone 1 (O-acetyloxime) (trade name: OXE-02, manufactured by Ciba Specialty Chemicals), 1-phenyl-1,2-propanedione-2- [O- (ethoxycarbonyl) oxime] (trade name: Quanture- PDO, manufactured by Nippon Kayaku Co., Ltd.).

  Examples of quinones include 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenyl. Examples include anthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, and 2,3-dimethylanthraquinone.

Examples of the benzoin ether compound include benzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether.

Examples of the benzyl derivative include benzoin compounds such as benzoin, methylbenzoin, and ethylbenzoin, and benzyldimethyl ketal.

  Examples of the 2,4,5-triarylimidazole dimer include 2- (2-chlorophenyl) -1- [2- (2-chlorophenyl) -4,5-diphenyl-1,3-diazol-2- Yl] -4,5-diphenylimidazole, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4, 5-diphenylimidazole dimer is mentioned.

  Examples of the acridine derivative include 9-phenylacridine and 1,7-bis (9,9'-acridinyl) heptane.

  Examples of titanocene compounds include bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2- (1H-pyr-1-yl) ethyl) phenyl] titanium, bis (cyclopentadienyl). -Bis [2,6-difluoro-3- (2- (1H-pyr-1-yl) propyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2- (1H-pyr-1-yl) methyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (pyridin-1-yl) phenyl] titanium, bis (cyclopentadienyl) ) -Bis [2,6-difluoro-3- (2,5-dimethylpy-1-yl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2,5- Jie Rupy-1-yl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2,5-diisopropylpy-1-yl) phenyl] titanium, bis (cyclopentadienyl) ) -Bis [2,6-difluoro-3- (2,5-bisdimethylaminopy-1-yl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2) , 5-Dimethyl-3-methoxypy-1-yl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3-methoxyphenyl] titanium, bis (cyclopentadienyl) -bis [ 2,6-difluoro-3-isopropoxyphenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3-n-propoxyphenyl] Tan, and the like.

(C) The initiator may be synthesized by a conventional method, or a commercially available one may be obtained.
Examples of available initiators include Irgacure-369, Irgacure-907, Irgacure-651, Irgacure-819, Irgacure-OXE-01 (all of which are trade names, manufactured by Ciba Specialty Chemicals Co., Ltd.). Can be mentioned.

  Among the initiators described above, acylphosphine oxide, oxime esters, or titanocene compounds are particularly preferable from the viewpoint of improving photocurability and increasing sensitivity.

  (C) The content of the initiator is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total solid content of the photosensitive resin composition. It is especially preferable that it is 0.5-5 mass%. (C) When the content of the initiator is out of the above range, the sensitivity of the photosensitive resin composition tends to decrease or the compatibility may decrease as compared with the case where the content is within the above range. is there.

<Solvent>
The above-mentioned photosensitive resin composition may be dissolved in a solvent.
Examples of the solvent include nitrogen-containing solvents (N, N′-dimethylsulfoxide, N, N′-dimethylformamide, N, N′-diethylformamide, N, N′-dimethylacetamide, N, N′-diethyl. Acetamide, N-methyl-2-pyrrolidone, hexamethylenephosphoamide, N-methylpyrrolidone, etc.), lactones (γ-butyrolactone, γ-valerolactone, γ-caprolactone, ε-caprolactone, α-acetyl-γ-butyrolactone, α-methyl-γ-butyrolactone, etc.), alicyclic ketones (cyclohexanone, 4-methylcyclohexanone, etc.), ethers (3-methyl-3-methoxybutyl acetate, diethylene glycol dimethyl ether acetate, etc.), ethylene carbonate, propylene carbonate, etc. Carbonate solvent Glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, 4-chlorophenol, acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide Etc. are preferably employed. Furthermore, other common organic solvents, such as phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, ptyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, Tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, terpene, mineral spirit, petroleum naphtha solvent Etc. can also be added and used.

  The hygroscopic expansion coefficient of the 10 μm film after curing of the above-described photosensitive resin composition is 20 or less, and more preferably 10 or less.

[Hard disk suspension]
FIG. 1 is a sectional view showing a preferred embodiment of the hard disk suspension of the present invention. A hard disk suspension 10 shown in FIG. 1 includes a stainless steel foil 1, a polyimide 1 layer (PI 1 layer) 3 formed on the stainless steel foil 1, Cu wirings 7 provided at two locations on the PI 1 layer 3, An Au wiring 9 formed on the Cu wiring 7 and a polyimide two layer (PI2 layer) 5 provided on the PI1 layer 3 so as to cover the Cu wiring 7 and the Au wiring 9 are provided.

  The PI1 layer 3 functions as an interlayer insulating film, and the PI2 layer 5 functions as a surface protective film. These layers can be produced using the above-described photosensitive resin composition.

That is, the above-mentioned photosensitive resin composition is applied to a roll-shaped stainless steel foil (PI1 layer) and dried, exposed to I-line, G-line or H-line to form a pattern, using a developer. The PI1 layer 3 or the PI2 layer 5 can be manufactured through a developing step and a step of curing at 350 degrees for 1 hour.
The above-mentioned photosensitive resin composition is a negative type, and parts other than the exposed part are removed by development.

As mentioned above, although preferred embodiment of this invention was described, this invention is not restrict | limited to this.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

(Synthesis of polyimide precursor)
(Synthesis Example 1)
TFDB (6.841 g) is added as a diamine to a 200 mL separable flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a Dean-Stark reflux condenser, and 36.5 g of NMP is added as a solvent. Stir until the solution dissolves uniformly. When the diamine is completely dissolved, add PMDA (4.659 g) in portions as an acid dianhydride. The target polyimide precursor was obtained by stirring overnight at room temperature.

(Synthesis Examples 2 to 13)
A polyimide precursor was synthesized in the same manner as in Synthesis Example 1 except that the types and blending ratios of diamine and acid dianhydride were as shown in Table 5.
(Comparative Synthesis Examples 1-8)
A polyimide precursor was synthesized in the same manner as in Synthesis Example 1 except that the types and blending ratios of diamine and acid dianhydride were as shown in Table 6.

  The weight average molecular weights (Mw) of the polyimide precursors obtained in Synthesis Examples 1 to 13 and Comparative Synthesis Examples 1 to 8 are 42000 for Synthesis Example 1, 50000 for Synthesis Example 2, 48000 for Synthesis Example 3, and Synthesis Example. 4 is 38000, Synthesis example 5 is 50000, Synthesis example 6 is 52000, Synthesis example 7 is 43000, Synthesis example 8 is 41000, Synthesis example 9 is 51000, Synthesis example 10 is 60000, Synthesis example 11 is 49000, Synthesis example 12 is 55000, Synthesis Example 13 43000, Comparative Synthesis Example 1 50000, Comparative Synthesis Example 2 62000, Comparative Synthesis Example 3 71000, Comparative Synthesis Example 4 54000, Comparative Synthesis Example 5 56000, Comparative Synthesis Example 6 44000, Comparative Synthesis Example 7 was 49000 and Comparative Synthesis Example 8 was 49000.

Moreover, the weight average molecular weight of the polyimide precursor was converted from a calibration curve using standard polystyrene by gel permeation chromatography (GPC). The measurement conditions for GPC are shown below.
Detector: Hitachi D-2520GPC Integrator
Pump: Hitachi L-2130 pump column: Hitachi GL-S300MDT-5 column guard column: Hitachi GL-S300MDT-5 guard column

(Examples 2-5, 7, 8, 10, 12-15, Reference Examples 1 , 6 , 9 , 11 , Comparative Examples 1-5)
The polyimide precursor synthesized by the above method is combined with any one of MDAP, BPA-BDAM, and / or MME as a crosslinking agent, and titanocene or Irg-OXE-01 is added as an initiator. The photosensitive resin compositions of Examples 2 to 5, 7, 8, 10, 12 to 15, Reference Examples 1, 6, 9, and 11 and Comparative Examples 1 to 5 were prepared. The amounts of the blended components are as shown in Tables 9 and 10.

Here, BPA-BDAM is synthesized by the following method. Into a 1 liter reaction vessel equipped with a thermometer and a stirrer, 380.0 g (2.0 mol) of 1,3-phenylenebisoxazoline and 228.0 g (1.0 mol) of bisphenol A were added and stirred at 150 ° C. for 10 hours. did. Thereafter, methoquinone (500 ppm) and methacrylic acid 140.0 g (2.0 mol) were added and stirred at 100 ° C. for 6 hours, and 190 g of dimethylacetamide was added dropwise. The mixture was further stirred at 100 ° C. for 6 hours. When the acid value reached 1.1 mg KOH / g, the stirring was stopped, and the compound represented by the following formula (20) which is a photopolymerizable unsaturated compound (BPA- BDAM) solution was obtained. The solid content of the obtained solution was 80% by mass.

MDAP and MME are amine compounds each having a (meth) acryloyl group represented by the following structure.

[Evaluation of various properties]
The humidity expansion coefficient of the polyimide resins prepared in Examples and Comparative Examples was evaluated by the following method. The results are shown in Tables 7 and 8. A theoretical calculation method for predicting a low CHE polymer is shown below.

<Developability>
The photosensitive resin compositions of Examples 2 to 5, 7, 8, 10, 12 to 15, Reference Examples 1, 6, 9, and 11 and Comparative Examples 1 to 5 were spin-coated on a silicon wafer, and 85 The mixture was heated at 0 ° C. for 2 minutes and exposed at 800 mJ / cm ² with an i-line stepper through 21 step tablet steps. Thereafter, development was performed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution, and A was designated as A where the fifth step of the step tablet did not peel off, and B was designated as other.

<Measurement of hygroscopic expansion coefficient (CHE)>
The photosensitive resin compositions of Examples 2 to 5, 7, 8, 10, 12 to 15, Reference Examples 1, 6, 9, and 11 and Comparative Examples 1 to 5 were applied onto a silicon wafer, and 75 ° C. The film was heated for 2 minutes, then at 85 ° C. for 2 minutes, and exposed at 800 mJ / cm ² with an i-line stepper. After the exposure, it was heated at 350 ° C. for 1 hour to obtain a cured polyimide film having a thickness of 10 μm.

The obtained cured film was peeled off from the silicon wafer and cut into a 5 mm × 20 mm strip (length between chucks: 15 μm). The length of the test membrane when measured by TMA and changed from 20% RH (1 hour) to 80% RH (1 hour) at a constant load (250 mN) and constant temperature (25 degrees) over 1 hour. The humidity expansion coefficient was calculated by the following equation.

Hygroscopic expansion coefficient (ppm / RH%) = [(XY) / 15 ^{* 1} ] × [100/60 ^{* 2} ]
X = length of membrane at 80% humidity (μm)
Y = Membrane length at 20% humidity (μm)
¹ : Length of measurement range (μm)
² : Amount of change in humidity (80% -20%)

<Measurement of low linear thermal expansion coefficient (CTE)>
Each polyimide precursor resin composition of Examples 2 to 5, 7, 8, 10, 12 to 15, Reference Examples 1, 6, 9, and 11 and Comparative Examples 1 to 5 was applied on a silicon wafer, and 75 degrees. For 2 minutes, followed by heating at 85 ° C. for 2 minutes and exposure at 800 mJ / cm ² with an i-line stepper. After the exposure, it was heated at 350 ° C. for 1 hour to obtain a cured polyimide film having a thickness of 10 μm.

The obtained cured film was cut into 2 mm × 3 cm, and heated to 30 to 420 ° C. (heating rate 5 ° C./min) while applying a weight of 10 g / min using a TMA / SS6000 thermomechanical measuring device manufactured by Seiko. did. CTE was measured by measuring the slope of the elongation of the cured film between 100 and 200 ° C.

Claims (5)

(A) A photosensitive resin composition for a hard disk suspension, comprising a polyimide resin having a structure represented by the following general formula (1) or a precursor thereof, (B) a crosslinking agent, and (C) an initiator.

[In the formula (1), Ar is

R represents a tetravalent organic group selected from the group represented by: R represents one divalent organic group having no ether group and carbonyl group and containing an F atom, and n represents 1 or more. Indicates an integer. ] R is

[Wherein, m, l, n, j and k represent an integer of 1 to 10 , and i represents an integer of 1 to 10. ]
In a divalent organic group having 1 kind selected Ru from the group represented, the photosensitive resin composition of claim 1.   The photosensitive resin composition of Claim 1 or 2 whose hydrophilicity parameter of the said (A) component is -7--3.   The manufacturing method of the resist pattern which has the process of apply | coating and drying the photosensitive resin composition as described in any one of Claims 1-3 on a support substrate, the process of exposing, and the process of developing using a developing solution.   A hard disk suspension having a resist pattern obtained by the manufacturing method according to claim 4 as a surface protective film and / or an interlayer insulating film.

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