JP6164070B2 - POLYIMIDE PRECURSOR, RESIN COMPOSITION CONTAINING THE POLYIMIDE PRECURSOR, METHOD FOR PRODUCING PATTERN CURED FILM USING SAME, AND SEMICONDUCTOR DEVICE - Google Patents

Description

  The present invention relates to a polyimide precursor, a resin composition containing the polyimide precursor, a method for producing a patterned cured film using the polyimide precursor, and a semiconductor device.

In recent years, organic materials having high heat resistance such as polyimide resin have been widely applied as protective film materials for semiconductor integrated circuits (LSIs).
A protective film (cured film) using such a polyimide resin is obtained by heating and curing a resin film formed by applying and drying a polyimide precursor or a resin composition containing a polyimide precursor on a substrate. It is obtained by.

With the miniaturization of semiconductor integrated circuits, it is necessary to reduce the dielectric constant of an interlayer insulating film called a low-k layer. In order to reduce the dielectric constant, for example, there is a method of applying an interlayer insulating film having a hole structure. However, this method has a problem that the mechanical strength is lowered. In order to protect such an interlayer insulating film having low mechanical strength, there is a method of providing a protective film on the interlayer insulating film.
In addition, in the region where the protruding external electrodes called bumps are formed, the protective film has a thick film formability (for example, 5 μm) so that the stress acting on the interlayer insulating film is concentrated and the interlayer insulating film is not destroyed. The demand for higher elasticity (for example, 4 GPa or more) is increasing. However, by increasing the thickness of the protective film and increasing the elastic modulus, the stress of the protective film increases and the warp of the semiconductor wafer increases, which may cause problems during transportation and wafer fixing. Therefore, development of a low stress polyimide resin is desired.

  As a method for reducing the stress of the polyimide resin, a method in which the molecular chain of the polyimide is made to have a rigid skeleton in order to make the thermal expansion coefficient of the polyimide close to the thermal expansion coefficient of the silicon wafer (for example, Patent Document 1). And a method of reducing the elastic modulus of polyimide by introducing a flexible structure (for example, Patent Document 2).

On the other hand, when the polyimide resin used for forming the protective film is photosensitive, a pattern cured film (patterned cured film) can be easily formed.
As a method for making the polyimide resin photosensitive, there is a method for imparting photosensitivity to the polyimide. As a method for imparting photosensitivity to polyimide, a method of introducing a methacryloyl group into a polyimide precursor via an ester bond or an ionic bond, a method of using a soluble polyimide having a photopolymerizable olefin, a benzophenone skeleton, and nitrogen A method using a self-sensitized polyimide having an alkyl group at the ortho position of an aromatic ring to which atoms are bonded is known (for example, Patent Document 3). Among these methods, the method of introducing a methacryloyl group into a polyimide precursor via an ester bond can freely select a monomer used for synthesizing the polyimide precursor, and the methacryloyl group is chemically bonded. Therefore, it is characterized by excellent stability over time.

  However, in the low-stress polyimide resin described above, when a large amount of aromatic ring units are introduced in order to make the molecular chain a rigid skeleton, many conjugated aromatic ring units are contained in the molecular chain. Even the polyamic acid (polyimide precursor) which is a precursor of the compound has absorption in the ultraviolet region. Therefore, the transmittance of i-line (wavelength 365 nm) widely used in the exposure process for forming the patterned resin film tends to decrease, and the sensitivity and resolution tend to decrease.

  In addition, a polyimide having a structural unit based on pyromellitic dianhydride is suitable for lowering stress, but it is necessary to use a diamine compound containing a fluorine atom having high i-line transmittance from the viewpoint of pattern formation. . However, when the polyimide precursor synthesize | combined from the structural unit based on pyromellitic dianhydride and the diamine compound containing a fluorine atom was used, the subject that a viscosity change arose in the solvent occurred.

JP-A-5-295115 JP 7-304950 A JP-A-7-242744

  An object of the present invention is to provide a resin composition having a small change in viscosity at room temperature.

（一般式（１）中、Ｂは、下記一般式（２）で表される２価の有機基である。
Ｒ^１及びＲ^２は、それぞれ独立に、水素原子、又は１価の有機基である。）

（一般式（２）中、Ｒ^３〜Ｒ^１０は、それぞれ独立に、水素原子、フッ素原子、トリフルオロメチル基、又はメチル基である。但し、Ｒ^３〜Ｒ^１０の少なくとも１つは、フッ素原子、トリフルオロメチル基、又はメチル基である。）
２．前記ポリイミド前駆体が、さらに下記一般式（３）で表される構造単位を有する、１に記載の樹脂組成物。

（一般式（３）中、Ｄは下記一般式（４）で表される４価の有機基である。
Ｂ、Ｒ^１及びＲ^２は、それぞれ前記一般式（１）と同じである。）

（一般式（４）中、Ｚは、エーテル結合（−Ｏ−）である。）
３．前記ポリイミド前駆体が、一般式（１）で表される構造単位を全構造単位に対して５０ｍｏｌ％以上有するポリイミド前駆体である１又は２に記載の樹脂組成物。
４．さらに、（ｂ）活性光線照射によってラジカルを発生する化合物、（ｃ）溶剤とを含有する、１〜３のいずれかに記載の樹脂組成物。
５．１〜４のいずれかに記載の樹脂組成物を加熱して得られる硬化膜。
６．１〜４のいずれかに記載の樹脂組成物を基板上に塗布し乾燥して塗膜を形成する工程、
前記形成した塗膜に活性光線を照射してパターン状に露光する工程、
前記露光部以外の未露光部を現像によって除去してパターン樹脂膜を得る工程、及び
パターン樹脂膜を加熱処理する工程を含むパターン硬化膜の製造方法。
７．６に記載のパターン硬化膜の製造方法で得られるパターン硬化膜を有する半導体装置。 According to the present invention, the following resin composition and the like are provided.
1. A resin composition comprising a polyimide precursor having a structural unit represented by the following general formula (1) and 2,4,6-trimethylpyridinium p-toluenesulfonate.

(In General Formula (1), B is a divalent organic group represented by the following General Formula (2).
R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group. )

(In General Formula (2), R ^{3 to} R ¹⁰ are each independently a hydrogen atom, a fluorine atom, a trifluoromethyl group, or a methyl group, provided that at least one of R ^{3 to} R ¹⁰ is fluorine. An atom, a trifluoromethyl group, or a methyl group.)
2. 2. The resin composition according to 1, wherein the polyimide precursor further has a structural unit represented by the following general formula (3).

(In General Formula (3), D is a tetravalent organic group represented by the following General Formula (4).
B, R ¹ and R ² are the same as in the general formula (1), respectively. )

(In General Formula (4), Z is an ether bond (—O—).)
3. 3. The resin composition according to 1 or 2, wherein the polyimide precursor is a polyimide precursor having 50 mol% or more of the structural unit represented by the general formula (1) with respect to all structural units.
4). Furthermore, the resin composition in any one of 1-3 containing the compound which generate | occur | produces a radical by (b) actinic ray irradiation, and (c) solvent.
The cured film obtained by heating the resin composition in any one of 5.1-4.
The process of apply | coating the resin composition in any one of 6.1-4 on a board | substrate, and drying and forming a coating film,
Irradiating an actinic ray to the formed coating film and exposing it in a pattern,
A method for producing a patterned cured film, comprising: removing a non-exposed portion other than the exposed portion by development to obtain a patterned resin film; and heating the pattern resin film.
A semiconductor device having a patterned cured film obtained by the method for producing a patterned cured film according to 7.6.

  According to the present invention, a resin composition with little change in viscosity at room temperature can be provided.

（一般式（１）中、Ｂは、下記一般式（２）で表される２価の有機基である。
Ｒ^１及びＲ^２は、それぞれ独立に、水素原子、又は１価の有機基である。）

（一般式（２）中、
Ｒ^３〜Ｒ^１０は、それぞれ独立に、水素原子、フッ素原子、トリフルオロメチル基、又はメチル基である。但し、Ｒ^３〜Ｒ^１０の少なくとも１つは、フッ素原子、トリフルオロメチル基、又はメチル基である。） The resin composition of the present invention contains a polyimide precursor having a structural unit represented by the following general formula (1) and 2,4,6-trimethylpyridinium p-toluenesulfonate.

(In General Formula (1), B is a divalent organic group represented by the following General Formula (2).
R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group. )

(In general formula (2),
R ^{3 to} R ¹⁰ are each independently a hydrogen atom, a fluorine atom, a trifluoromethyl group, or a methyl group. However, at least one of R ^{3 to} R ¹⁰ is a fluorine atom, a trifluoromethyl group, or a methyl group. )

The polyimide precursor can be synthesized by addition polymerization of tetracarboxylic dianhydride and diamine. At that time, the tetracarboxylic dianhydride is converted into an acid chloride via a diester derivative. . Although chlorine ions remain in the composition containing the polyimide precursor, the stability of the resin composition can be improved. However, in semiconductor applications, the chlorine ions cause disconnection.
In the resin composition of the present invention, by including 2,4,6-trimethylpyridinium p-toluenesulfonate, the acidity in the composition can be within an appropriate range, and the polyimide precursor and polyimide in the composition It is presumed that changes in viscosity due to interaction with components other than the precursor can be suppressed. If the viscosity changes by about 10% from the initial viscosity (viscosity immediately after preparation of the composition), it becomes difficult to adjust the thickness of the coating film obtained when coating is formed by spin coating or the like. In the suppressed composition of the present invention, the thickness of the obtained coating film can be easily adjusted.

The resin composition of the present invention is not particularly limited as long as it includes a polyimide precursor having the structural unit represented by (1) and 2,4,6-trimethylpyridinium p-toluenesulfonate. For example, the following components ( Contains a) to (d):
(A) Polyimide precursor having a structural unit represented by formula (1) (b) Compound that generates radicals upon irradiation with actinic rays (c) 2,4,6-trimethylpyridinium p-toluenesulfonate (d) Solvent Hereinafter, each component of the present invention will be described.

（一般式（１）中、Ｂは、下記一般式（２）で表される２価の有機基である。
Ｒ^１及びＲ^２は、それぞれ独立に、水素原子、又は１価の有機基である。）

（一般式（２）中、
Ｒ^３〜Ｒ^１０は、それぞれ独立に、水素原子、フッ素原子、トリフルオロメチル基、又はメチル基である。但し、Ｒ^３〜Ｒ^１０の少なくとも１つは、フッ素原子、トリフルオロメチル基、又はメチル基である。） [Polyimide precursor]
The polyimide precursor which is a component (a) has a structural unit represented by following General formula (1).

(In General Formula (1), B is a divalent organic group represented by the following General Formula (2).
R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group. )

(In general formula (2),
R ^{3 to} R ¹⁰ are each independently a hydrogen atom, a fluorine atom, a trifluoromethyl group, or a methyl group. However, at least one of R ^{3 to} R ¹⁰ is a fluorine atom, a trifluoromethyl group, or a methyl group. )

B in the general formula (1) is a structure derived from a diamine used as a raw material for the polyimide precursor, and is a divalent organic group represented by the general formula (2).
At least one of R ^{3 to} R ^{10 in} the general formula (2) is a fluorine atom, a trifluoromethyl group, or a methyl group, and preferably at least one of R ^{3 to} R ¹⁰ is a fluorine atom or a trifluoromethyl group. More preferably, two or more of R ^{3 to} R ¹⁰ are a fluorine atom, a trifluoromethyl group or a methyl group, and more preferably two or more of R ^{3 to} R ¹⁰ are a trifluoromethyl group.

  When the polyimide precursor has a hydrophobic group such as a fluorine atom or a trifluoromethyl group, the water absorption rate can be reduced. Therefore, when a protective film made of polyimide is formed by applying a composition containing the polyimide precursor on a semiconductor integrated circuit and curing by heating, the protective film is a film having a low water absorption. Such a protective film can shorten the evacuation time and suppress the contamination of the vapor deposition apparatus in a high vacuum process such as metal thin film vapor deposition in the bump forming step, and can improve productivity.

Examples of the diamine that gives the structure of B include diamines represented by the following general formulas (14) to (20).
During polymerization of the polyimide precursor, these may be used alone or in combination of two or more diamines.

  Among these diamines, diamines represented by formula (14), formula (19) and formula (20) are preferable from the viewpoint of i-line transmittance, and formula (19) and formula (20) from the viewpoint of low water absorption. It is more preferable to use a diamine represented by the formula (19), and a diamine represented by the formula (19) is particularly preferable.

R ¹ and R ² in the general formula (1) are each independently a hydrogen atom or a monovalent organic group.
Examples of the monovalent organic group include a (meth) acryloxyalkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 1 to 20 carbon atoms, and an alkyl group having 1 to 10 carbon atoms in the alkyl moiety. Is mentioned.
Examples of the alkyl group include ethanol, isopropyl alcohol, trifluoromethanol, fentyl alcohol, methanol, n-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, n-propyl alcohol, and n-heptyl alcohol. Examples include residues (alcohol residues) excluding a hydroxyl group. Among these, from the viewpoint of preventing gelation, a residue obtained by removing a hydroxyl group from ethanol or trifluoroethanol is preferable.
Examples of the (meth) acryloxyalkyl group include a (meth) acryloxyethyl group, a (meth) acryloxypropyl group (meth) acryloxybutyl group, and the like. Of these, a (meth) acryloxyethyl group is preferred.

Since the polyimide precursor includes the structure represented by the general formula (1), the molecular chain of the polyimide becomes stiff so that the thermal expansion can be reduced and the stress can be reduced.
The structure represented by the general formula (1) is preferably 60 mol% or more with respect to all structural units, and more preferably 70 mol% or more with respect to all structural units. The upper limit of the ratio of the structure represented by the general formula (1) in the polyimide precursor is not particularly limited, but is preferably 95 mol% or less, for example, 90 mol% or less with respect to all structural units from the viewpoint of reducing stress and suppressing viscosity. More preferably, it is more preferably 80 mol% or less.
In order to make the ratio of the structure represented by the general formula (1) within the above range, the blending amount of tetracarboxylic dianhydride and diamine during polymerization of the polyimide precursor may be adjusted as appropriate.

（一般式（３）中、Ｄは下記一般式（４）で表される４価の有機基である。
Ｂ、Ｒ^１及びＲ^２は、それぞれ前記一般式（１）と同じである。）

（一般式（４）中、Ｚは、エーテル結合（−Ｏ−）である。） The polyimide precursor has a structure represented by the following general formula (3) in addition to the structure represented by the general formula (1) for the purpose of improving i-line transmittance, adhesion after curing, and mechanical properties. May be.

(In General Formula (3), D is a tetravalent organic group represented by the following General Formula (4).
B, R ¹ and R ² are the same as in the general formula (1), respectively. )

(In General Formula (4), Z is an ether bond (—O—).)

  In General formula (3), the part containing Z is a structure derived from the tetracarboxylic dianhydride which is a raw material of a polyimide precursor. Examples of the tetracarboxylic dianhydride that gives the structure of the moiety containing Z include 4,4'-oxydiphthalic dianhydride.

Formula (3) B, ^{R 1} and ^{R 2,} general formula (1) B, it is the same as ^{R 1} and ^{R 2,} B preferred group formula (1), ^{R 1} and ^{R 2} The same.

  When the polyimide precursor has both the structural unit represented by the general formula (1) and the structural unit represented by the general formula (3), the polyimide precursor is copolymerized. Examples of the copolymer of the polyimide precursor include a block copolymer and a random copolymer, but are not particularly limited.

  In the case where the polyimide precursor has both the structural unit represented by the general formula (1) and the structural unit represented by the general formula (3), from the viewpoint of obtaining lower stress and better i-line transmittance, The molar ratio of the structural unit represented by the formula (1) and the structural unit represented by the general formula (3) [formula (1) / formula (3)] is preferably 5/5 to 9/1. More preferably, it is 6/4 to 9/1, and more preferably 7/3 to 9/1.

The polyimide precursor may have a structural unit (other structural unit) other than the structural unit represented by the general formula (1) and the structural unit represented by the general formula (3).
Examples of tetracarboxylic dianhydrides that give other structural units include 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 1 2,3,4-cyclobutanetetracarboxylic dianhydride and the like. Examples of diamines that give other structural units include paraphenylene diamine, 4,4′-oxydianiline, 2,2′-dimethylbenzidine, 4,4′-diaminodiphenylmethane, and the like.

From the viewpoint of stress and i-line transmittance, the tetracarboxylic dianhydride providing other structural units is preferably 20 mol% or less based on the total amount of tetracarboxylic dianhydride used as a raw material for the polyimide precursor. More preferably, it is 10 mol% or less. Particularly preferably, only tetracarboxylic dianhydrides that give the structures of the general formulas (1) and (3) are used without using tetracarboxylic dianhydrides that give other structural units.
The diamine giving other structure is preferably 20 mol% or less, and preferably 10 mol% or less, based on the total amount of diamine. Particularly preferably, only diamines giving the structure of general formula (3) are used.

As for the molecular weight of a polyimide precursor, it is preferable that the weight average molecular weights in polystyrene conversion are 10,000-100000, It is more preferable that it is 15000-100,000, It is further more preferable that it is 20000-85000.
When the weight average molecular weight of the polyimide precursor is 10,000 or more, the stress after curing can be sufficiently reduced. When the weight average molecular weight of the polyimide precursor is 100,000 or less, it is possible to improve the solubility in a solvent or to prevent the handleability from decreasing due to an increase in the viscosity of the solution.
In addition, a weight average molecular weight can be measured by the gel permeation chromatography method, and can be calculated | required by converting using a standard polystyrene calibration curve.

（一般式（２１）及び（２２）中、
Ｑは、一般式（１）のベンゼン環、又は一般式（３）中のＤの構造を表す。） Although there is no restriction | limiting in particular in the synthesis | combining method of a polyimide precursor, For example, it can synthesize | combine by addition-polymerizing tetracarboxylic dianhydride and diamine. Moreover, after derivatizing the tetracarboxylic dianhydride as a raw material into a diester derivative represented by the following general formula (21), it is converted to an acid chloride represented by the following general formula (22), and diamine and basic It can also be synthesized by condensation in the presence of a compound (for example, pyridine).

(In the general formulas (21) and (22),
Q represents the benzene ring of the general formula (1) or the structure of D in the general formula (3). )

  The molar ratio of tetracarboxylic dianhydride and diamine (tetracarboxylic dianhydride / diamine) in synthesizing the polyimide precursor is usually preferably 1.0, but the molecular weight and terminal residue are controlled. For the purpose, it may be carried out at a molar ratio in the range of 0.7 to 1.3.

The diester derivative represented by the formula (21) can be synthesized by reacting at least 2 molar equivalents of alcohol in the presence of a basic catalyst with respect to 1 mol of tetracarboxylic dianhydride as a raw material. it can.
However, when the diester derivative represented by the formula (21) is converted into the acid chloride represented by the formula (22), if unreacted alcohol remains, the chlorinating agent becomes unreacted alcohol and Since it reacts and there is a concern that the conversion to an acid chloride does not proceed sufficiently, the equivalent of alcohol is preferably 2.0 to 2.5 molar equivalent, and preferably 2.0 to 2 More preferably, it is 3 molar equivalents, more preferably 2.0-2.2 molar equivalents.

Alcohols used for the synthesis of diester derivatives include alcohols having an alkyl group having 1 to 20 carbon atoms, alcohols having a cycloalkyl group having 1 to 20 carbon atoms, and (meth) acrylates having an alkyl moiety having 1 to 10 carbon atoms. Alcohols having a roxyalkyl group can be used.
For example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, t-butanol, hexanol, cyclohexanol, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy Examples include butyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. These may be used singly or in combination of two or more.

  As the basic catalyst used for the synthesis of the diester derivative, 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,5-diazabicyclo [4.3.0] non-5-ene or the like is used. be able to.

  When using two or more kinds of tetracarboxylic dianhydrides as raw materials used in the synthesis of the diester derivative, they may be used by mixing each of the tetracarboxylic dianhydrides separately led to an ester derivative, Two or more kinds of tetracarboxylic dianhydrides may be mixed in advance and then led to an ester derivative at the same time.

In order to convert the diester derivative represented by the formula (21) into the acid chloride represented by the formula (22), it is usually used by reacting 1 mol of the diester derivative with 2 mol equivalent of a chlorinating agent. However, in order to control the molecular weight of the synthesized polyimide precursor, the equivalent may be appropriately adjusted.
As the chlorinating agent, thionyl chloride and dichlorooxalic acid can be used, and the amount used is preferably 1.5 to 2.5 molar equivalents relative to 1 mol of the diester derivative, and 1.6 to 2.4. The molar equivalent is more preferable, and 1.7 to 2.3 molar equivalent is more preferable.
If the amount of chlorinating agent used is less than 1.5 molar equivalents, the molecular weight of the resulting polyimide precursor may be too low and stress after curing may not be sufficiently reduced. There is a risk that unreacted chlorinating agent and raw material diamine may react.

A polyimide precursor is obtained by adding the diamine which is a raw material to acid chloride represented by Formula (22) in the presence of a basic compound. The basic compound is used for the purpose of capturing hydrogen chloride generated when the acid chloride and diamine react.
As the basic compound, for example, pyridine, 4-dimethylaminopyridine, triethylamine and the like can be used, and it is preferably used in an amount of 1.5 to 2.5 times the amount of the chlorinating agent. The amount is preferably 2.4 times, and more preferably 1.8 to 2.3 times. If the amount of the basic compound used is less than 1.5 times, the molecular weight of the polyimide precursor may be lowered, and if the amount of the basic compound used is more than 2.5 times, the polyimide precursor is There is a risk of coloring.

The above addition polymerization, condensation reaction, and synthesis of diester derivatives and acid chlorides are preferably performed in an organic solvent.
The organic solvent to be used is preferably a polar solvent that completely dissolves the polyimide precursor to be synthesized, such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, tetramethyl. Examples include urea, hexamethylphosphoric triamide, and γ-butyrolactone.

  When a polyimide precursor is synthesized by the above-described method, the polyimide precursor is obtained as a reaction liquid in which a solvent or the like is mixed. The obtained reaction solution is dropped into distilled water, collected by filtration, washed several times with distilled water, and vacuum dried to obtain a polyimide precursor (polyamic acid ester). Washing with distilled water is preferably performed twice or more. The polyimide precursor (polyamic acid ester) once washed with distilled water and dried is dissolved again in a solvent, similarly dropped in distilled water, washed several times with distilled water, and then vacuum dried. The washing with distilled water at this time is preferably performed 5 times or more. By such a process, the chlorine concentration in the polyimide precursor can be reduced, and as a result, the chlorine concentration in the resin composition can be suppressed.

A polyimide having a structural unit based on pyromellitic dianhydride and using a diamine compound containing a fluorine atom usually interacts with a solvent to cause a change in viscosity at room temperature. However, when a polyimide precursor is synthesized by the above-described method and pyridine is used as the basic compound, for example, when pyridine hydrochloride is contained in an amount of 50 ppm or more, a change in viscosity can be suppressed. On the other hand, when applied as a semiconductor application, chlorine derived from pyridine hydrochloride causes disconnection, and thus the chlorine content is preferably reduced.
The resin composition of the present invention has a viscosity at room temperature by adding 2,4,6-trimethylpyridinium p-toluenesulfonate even when, for example, a polyimide precursor having a residual amount of pyridine hydrochloride of 50 ppm or less is used. Change can be suppressed.

  The polyimide precursor as component (a) is preferably contained in the resin composition in an amount of 20 to 60% by mass, more preferably 25 to 55% by mass, and further preferably 30 to 55% by mass. .

[Compounds that generate radicals upon irradiation with actinic rays]
Examples of compounds that generate radicals upon irradiation with actinic rays as component (b) include N, such as oxime ester compounds, benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), which will be described later. , N′-tetraalkyl-4,4′-diaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-methyl-1- [4- (methylthio) phenyl An aromatic ketone such as 2-morpholino-propanone-1; a quinone fused with an aromatic ring such as alkylanthraquinone; a benzoin ether compound such as benzoin alkyl ether; a benzoin compound such as benzoin or alkylbenzoin; a benzyldimethyl ketal Of the benzyl derivative.
Among these, an oxime ester compound is preferable because it is excellent in sensitivity and gives a good pattern.

  The oxime ester compound is represented by the following formula (7), the following formula (8), and the following formula (9) from the viewpoint of obtaining good sensitivity and remaining film ratio. It is preferable that it is any one of the following compounds.

（式（７）中、Ｒ及びＲ_１は、それぞれ炭素数１〜１２のアルキル基、炭素数４〜１０のシクロアルキル基、又はフェニル基を示し、炭素数１〜８のアルキル基、炭素数４〜６のシクロアルキル基又はフェニル基であることが好ましく、炭素数１〜４のアルキル基、炭素数４〜６のシクロアルキル基又はフェニル基であることがより好ましく、メチル基、シクロペンチル基又はフェニル基であることがさらに好ましい。
Ｒ_２は、Ｈ、ＯＨ、ＣＯＯＨ、Ｏ（ＣＨ_２）ＯＨ、Ｏ（ＣＨ_２）_２ＯＨ、ＣＯＯ（ＣＨ_２）ＯＨ又はＣＯＯ（ＣＨ_２）_２ＯＨを示し、Ｈ、Ｏ（ＣＨ_２）ＯＨ、Ｏ（ＣＨ_２）_２ＯＨ、ＣＯＯ（ＣＨ_２）ＯＨ又はＣＯＯ（ＣＨ_２）_２ＯＨであることが好ましく、Ｈ、Ｏ（ＣＨ_２）_２ＯＨ又はＣＯＯ（ＣＨ_２）_２ＯＨであることがより好ましい。）

(In the formula (7), R and _{R 1} are each an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, or a phenyl group having 4 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, carbon atoms It is preferably a cycloalkyl group having 4 to 6 carbon atoms or a phenyl group, more preferably an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 4 to 6 carbon atoms or a phenyl group, and a methyl group, cyclopentyl group or More preferably, it is a phenyl group.
R ₂ represents H, OH, COOH, O (CH ₂ ) OH, O (CH ₂ ) ₂ OH, COO (CH ₂ ) OH or COO (CH ₂ ) ₂ OH, and H, O (CH ₂ ) OH O (CH ₂ ) ₂ OH, COO (CH ₂ ) OH or COO (CH ₂ ) ₂ OH is preferred, and H, O (CH ₂ ) ₂ OH or COO (CH ₂ ) ₂ OH is preferred. More preferred. )

（式（８）中、Ｒ_３は、それぞれ炭素数１〜６のアルキル基を示し、プロピル基であることが好ましい。
Ｒ_４は、ＮＯ_２又はＡｒＣＯ（ここで、Ａｒはアリール基を示す。）を示し、Ａｒとしては、トリル基が好ましい。
Ｒ_５及びＲ_６は、それぞれ炭素数１〜１２のアルキル基、フェニル基、又はトリル基を示し、メチル基、フェニル基又はトリル基であることが好ましい。）

(In Formula (8), R < ₃ > shows a C1-C6 alkyl group, respectively, and it is preferable that it is a propyl group.
R ₄ represents NO ₂ or ArCO (wherein Ar represents an aryl group), and Ar is preferably a tolyl group.
R ₅ and R ₆ each represent an alkyl group having 1 to 12 carbon atoms, a phenyl group, or a tolyl group, and is preferably a methyl group, a phenyl group, or a tolyl group. )

（式（９）中、Ｒ_７は、炭素数１〜６のアルキル基を示し、エチル基であることが好ましい。
Ｒ_８はアセタール結合を有する有機基であり、後述する式（９−１）に示す化合物が有するＲ_８に対応する置換基であることが好ましい。
Ｒ_９及びＲ_１０は、それぞれ炭素数１〜１２のアルキル基、フェニル基又はトリル基を示し、メチル基、フェニル基又はトリル基であることが好ましく、メチル基であることがより好ましい。
尚、芳香環には、Ｒ_８以外の置換基を有してもよい。）

(In the formula (9), _{R 7} represents an alkyl group having 1 to 6 carbon atoms is preferably an ethyl group.
R ₈ is an organic group having an acetal bond, and is preferably a substituent corresponding to R ₈ included in the compound represented by the formula (9-1) described later.
R ₉ and R ₁₀ each represent an alkyl group having 1 to 12 carbon atoms, a phenyl group, or a tolyl group, preferably a methyl group, a phenyl group, or a tolyl group, and more preferably a methyl group.
The aromatic ring may have a substituent other than R ₈ . )

Examples of the compound represented by the formula (7) include a compound represented by the following formula (7-1) and a compound represented by the following formula (7-2). Among these, the compound represented by the following formula (7-1) is available as IRGACURE OXE-01 (trade name, manufactured by BASF Corporation).

Examples of the compound represented by the above formula (8) include a compound represented by the following formula (8-1). This compound is available as DFI-091 (trade name, manufactured by Daito Chemix Co., Ltd.).

Examples of the compound represented by the above formula (9) include a compound represented by the following formula (9-1). It is available as Adekaoptomer N-1919 (manufactured by ADEKA, trade name).

As other oxime ester compounds, the following compounds are preferably used.

Moreover, the following compounds can also be used as the component (c).

  As content of the compound which generate | occur | produces a radical by irradiation of actinic light, it is preferable that it is 0.01-10 weight part with respect to 100 weight part of polyimide precursors, and it is 0.01-5 weight part. More preferred is 0.05 to 3 parts by weight. When the blending amount is 0.01 parts by weight or more, crosslinking of the exposed part proceeds more sufficiently, and the photosensitive properties (sensitivity, resolution) of the composition tend to be better, and when it is 10 parts by weight or less. The heat resistance of the cured film obtained can be made better.

[solvent]
The solvent that is component (d) is preferably a polar solvent that completely dissolves the polyimide precursor that is component (a). Examples of the polar solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, tetramethylurea, hexamethylphosphoric triamide, γ-butyrolactone, and δ-valerolactone. , Γ-valerolactone, cyclohexanone, cyclopentanone, propylene glycol monomethyl ether acetate, propylene carbonate, ethyl lactate, and 1,3-dimethyl-2-imidazolidinone. These may be used alone or in combination of two or more. Of these solvents, N-methyl-2-pyrrolidone is preferred.

  The content of the solvent is preferably 40 to 80% by mass, more preferably 45 to 75% by mass, and still more preferably 45 to 70% by mass in the resin composition.

[Other ingredients]
The resin composition of the present invention comprises (a) a polyimide precursor, (b) a compound that generates radicals upon irradiation with actinic rays, (c) 2,4,6-trimethylpyridinium p-toluenesulfonate, and (d) A solvent may be included, and the following other components may be further included.

  The resin composition of the present invention may contain (e) an organosilane compound in order to improve adhesion to a cured silicon substrate or the like. A conventionally well-known thing can be especially used as an organosilane compound without a restriction | limiting.

The resin composition of the present invention may contain (f) an addition polymerizable compound as necessary.
Examples of the addition polymerizable compound include diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol (meth) diacrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, styrene, divinylbenzene, 4-vinyltoluene, 4-vinylpyridine, N-vinylpyrrolidone, 2-hydroxyethyl (meth) acrylate, 1,3- (meth) acryloyloxy-2-hydroxypropane, methylenebisacrylamide, , N- dimethyl acrylamide, N- methylol acrylamide.
These addition polymerizable compounds may be used alone or in combination of two or more.

  When the resin composition contains an addition polymerizable compound, the content of the addition polymerizable compound is based on 100 parts by weight of the polyimide precursor from the viewpoint of solubility in a developer and heat resistance of a cured film to be obtained. 1 to 100 parts by weight, preferably 1 to 75 parts by weight, and more preferably 1 to 50 parts by weight.

  In order to ensure better storage stability, the resin composition of the present invention may contain (g) a radical polymerization inhibitor or a radical polymerization inhibitor. As the radical polymerization inhibitor or radical polymerization inhibitor, conventionally known ones can be used without any particular limitation.

The resin composition of the present invention may include at least one selected from components (a) to (d) and optionally components (e) to (g), and may consist essentially of these components, You may consist only of these components.
The “substantially” means, for example, that the total amount of components (a) to (d) and components (e) to (g) in the resin composition is 95% by weight or more and 97% by weight of the entire composition This means 98% by weight or more, or 99% by weight or more.

[Curing film]
A cured film is obtained by heat-treating the composition of the present invention to advance imidization.
As heating temperature which converts the polyimide precursor in a composition into a polyimide, 80-450 degreeC is preferable, 100-450 degreeC is more preferable, It is more preferable that it is 200-400 degreeC.
If it is less than 80 ° C., imidization does not proceed sufficiently and heat resistance may be lowered, and if heat treatment is performed at a temperature higher than 450 ° C., there is a possibility that a polyimide obtained by curing is deteriorated.

  The residual stress of the cured film obtained by curing the composition of the present invention is preferably 30 MPa or less, more preferably 27 MPa or less, and further preferably 25 MPa or less. When the resulting cured film has a residual stress of more than 30 MPa, when the cured film is formed thick so that the film thickness after curing is 10 μm, the warpage of the wafer becomes large, and there is a problem in transporting and fixing the wafer. May occur.

σ：残留応力（Ｐａ）
Ｅ／（１−ν）：シリコンウエハの二軸弾性係数（Ｐａ）
ｈ：シリコンウエハの厚さ（ｍ）
ｔ：ポリイミド膜厚（ｍ）
Ｒ：シリコンウエハの曲率半径の変化量（ｍ） The residual stress of the cured film can be calculated from the following formula (I) using the amount of change in the radius of curvature of the silicon wafer before and after the polyimide film is formed.
The curvature radius of the silicon wafer is calculated from the reflection angle of the laser that scans the silicon wafer, and can be measured using a thin film stress measuring device (for example, FLX-2320 manufactured by KLA Tencor).

σ: Residual stress (Pa)
E / (1-ν): Biaxial elastic modulus of silicon wafer (Pa)
h: thickness of silicon wafer (m)
t: Polyimide film thickness (m)
R: Change amount of curvature radius of silicon wafer (m)

In order to form a polyimide obtained by curing the polyimide precursor in the composition so as to have a film thickness of 10 μm after curing, for example, a polyimide precursor resin film is formed with a thickness of about 20 μm.
When the thickness of the polyimide precursor resin film obtained by applying and drying the composition on the substrate is 20 μm, the i-line transmittance of the resin film is preferably 5% or more, and preferably 8% or more. More preferably, it is more preferably 15% or more, and particularly preferably 30% or more. If the i-line transmittance is less than 5%, the i-line does not reach the deep part, and radicals are not sufficiently generated, so that the photosensitive characteristics may be deteriorated.
The i-line transmittance can be measured by, for example, forming a resin film by applying and drying a polyimide precursor on a glass plate, and measuring with an ultraviolet-visible spectrophotometer.

[Pattern cured film]
The cured pattern film of the present invention can be obtained by exposing and heating the resin composition of the present invention. The patterned cured film of the present invention is preferably used as a protective layer of a Low-K material that is an interlayer insulating film. Examples of the Low-K material include porous silica, benzocyclobutene, hydrogen silsesquioxane, polyallyl ether, and the like.

  The method for producing a patterned cured film of the present invention includes a step of applying the resin composition of the present invention on a substrate and drying to form a coating film, a step of irradiating the formed coating film with an actinic ray and exposing to a pattern And a step of removing a non-exposed portion other than the exposed portion by development to obtain a pattern resin film, and a step of heat-treating the pattern resin film.

In the step of applying a resin composition containing a polyimide precursor onto a substrate and drying to form a coating film, as a method of applying the resin composition onto the substrate, for example, an immersion method, a spray method, a screen printing method And spin coating method.
Examples of the substrate include a silicon wafer, a metal substrate, and a ceramic substrate. Since the resin composition containing the polyimide precursor of the present invention can form a low-stress cured film, it is particularly suitable for application to a silicon wafer having a large diameter of 12 inches or more.

After the resin composition is applied on the substrate, the solvent is removed (dried) by heating to form a coating film (resin film) with less adhesiveness.
In addition, it is preferable that the heating temperature at the time of drying is 80-130 degreeC, and it is preferable that drying time is 30-300 second. Drying is preferably performed using an apparatus such as a hot plate.

In the step of irradiating the coating film with an actinic ray to expose it in a pattern, and the step of removing the unexposed portion other than the exposed portion by development to obtain a patterned resin film, the pattern exposure is performed on the obtained coating film. Then, actinic rays are irradiated through a mask on which a desired pattern is drawn.
Although the resin composition of the present invention is suitable for i-line exposure, ultraviolet rays, far ultraviolet rays, visible rays, electron beams, X-rays, and the like can be used as the active rays to be irradiated.

A desired pattern can be obtained by dissolving and removing the unexposed portion with an appropriate developer after exposure.
Although there is no restriction | limiting in particular as a developing solution, Flame retardant solvents, such as 1,1,1-trichloroethane; Alkaline aqueous solutions, such as sodium carbonate aqueous solution and tetramethylammonium hydroxide aqueous solution; N, N- dimethylformamide, dimethyl sulfoxide, Good solvents such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, cyclopentanone, γ-butyrolactone, and acetates; and these good solvents and poor solvents such as lower alcohols, water, and aromatic hydrocarbons A mixed solvent or the like is used. After development, rinsing with a poor solvent (for example, water, ethanol, 2-propanol) or the like is performed as necessary.

In the process of heat-treating the pattern resin film, the resulting pattern resin film is heated at, for example, 80 to 400 ° C. for 5 to 300 minutes to advance the imidation of the polyimide precursor contained in the resin composition, thereby pattern curing. A membrane can be obtained.
In order to suppress the oxidative deterioration of the polyimide during heating, it is preferable to use a curing furnace that can be cured at a low oxygen concentration of 100 ppm or less, for example, an inert gas oven or a vertical diffusion furnace. Can do.

[Semiconductor device]
The semiconductor device of the present invention has a patterned cured film obtained by using the resin composition of the present invention. Examples of the semiconductor device include logic semiconductors such as MPU, and memory semiconductors such as DRAM and NAND flash.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to these Examples.

Example 1
[Synthesis of polyamic acid ester (polyimide precursor)]
Pyromellitic dianhydride, 2-hydroxyethyl methacrylate, and a catalytic amount of 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) were added in a weight ratio of pyromellitic dianhydride. Dissolved in 4 volumes of N-methyl-2-pyrrolidone and stirred at room temperature for 48 hours to give ester solution 1.
Further, 4,4′-oxydiphthalic anhydride, 2-hydroxyethyl methacrylate, and a catalytic amount of DBU were added in a weight ratio of 4 times the amount of 4,4′-oxydiphthalic dianhydride to N-methyl-2- Dissolved in pyrrolidone and stirred at room temperature for 48 hours to obtain ester solution 2.
The resulting ester solution 1 and ester solution 2 were mixed, and then cooled in an ice bath, and 2.2 times moles of the total amount of pyromellitic dianhydride and 4,4′-oxydiphthalic dianhydride. An equivalent amount of thionyl chloride was added dropwise, followed by stirring for 1 hour to prepare an acid chloride solution.
Separately, a solution is prepared by dissolving 2,2′-bis (trifluoromethyl) benzidine and 2-fold molar equivalent of pyridine of thionyl chloride in N-methyl-2-pyrrolidone 4 times as much as diamine 1 by weight. Then, the solution was added dropwise to the previously prepared acid chloride solution while cooling in an ice bath. After completion of dropping, the reaction solution was added dropwise to distilled water.
After completion of the dropwise addition, the precipitate was collected by filtration, washed several times with distilled water, and then vacuum dried to obtain a polyamic acid ester. 100 parts by weight of the resulting polyamic acid ester was dissolved in 150 parts by weight of N-methyl-2-pyrrolidone to prepare a polyamic acid ester solution.

  About the obtained polyamic-acid ester, when chlorine content (chlorine residual amount) was evaluated with potentiometric titrator COM-1700 (made by Hitachi High-Tech), it was 50 weight ppm.

[Preparation and Evaluation of Resin Composition]
100 parts by weight of the resulting polyamic acid ester, 20 parts by weight of tetraethylene glycol dimethacrylate, and 2 parts by weight of 1,2-octanedione-1- [4- (phenylthio) phenyl-2- (O-benzoyloxime)], Then, 3.5 parts by weight of 2,4,6-trimethylpyridinium p-toluenesulfonate is stirred until it is uniformly dissolved in 150 parts by weight of N-methyl-2-pyrrolidone, followed by pressure filtration using a 1 μm filter. Thus, a resin composition was obtained.
About the obtained resin composition, the viscosity change at room temperature of a varnish was evaluated. The results are shown in Table 1.

The viscosity change is evaluated by measuring the viscosity of the produced resin composition, storing the resin composition in a thermostatic chamber at 23 ° C. in the dark, and measuring the viscosity after 14 days and 25 days, respectively. did.
The viscosity was measured using an E-type rotational viscometer (VISCONIC EHD; manufactured by Toki Sangyo Co., Ltd.) at a measurement temperature of 25 ° C. and a rotation speed of 2.5 to 20 rpm.

Comparative Example 1-7
A resin composition was prepared and evaluated in the same manner as in Example 1 except that the compounds shown in Table 1 were used instead of 2,4,6-trimethylpyridinium p-toluenesulfonate. The results are shown in Table 1.
The polyamic acid ester used in Comparative Example 1 is a polyamic acid ester produced in the same manner as in Example 1 except that the amounts of thionyl chloride and pyridine were changed.

In addition, C1-C7 in Table 1 is the following compound, respectively.
C1: 2,4,6-trimethylpyridinium p-toluenesulfonate C2: pyridinium p-toluenesulfonate C3: 2-fluoro-1-methylpyridinium p-toluenesulfonate C4: 2,6-dimethylpyridinium p-toluenesulfo Nato C5: 2-chloro-1-methylpyridinium p-toluenesulfonate C6: pyridinium trifluoromethanesulfonate C7: 1-fluoro-2,4,6-trimethylpyridinium trifluoromethanesulfonate

  As shown in Table 1, in Example 1, the rate of change from the initial viscosity at 25 days after standing at room temperature is 10% or less, and the viscosity change is small, and low stress (16 MPa at 375 ° C./1 h cure, 270 ° C./4 h cure 24 MPa), and the viscosity change had no practical problem.

  The resin composition containing the polyimide precursor of the present invention can be suitably used as a protective film material or a pattern film forming material for electronic parts such as semiconductor devices.

Claims (7)

A resin composition comprising a polyimide precursor having a structural unit represented by the following general formula (1) and 2,4,6-trimethylpyridinium p-toluenesulfonate.

(In General Formula (1), B is a divalent organic group represented by the following General Formula (2).
R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group. )

(In General Formula (2), R ^{3 to} R ¹⁰ are each independently a hydrogen atom, a fluorine atom, a trifluoromethyl group, or a methyl group, provided that at least one of R ^{3 to} R ¹⁰ is fluorine. An atom, a trifluoromethyl group, or a methyl group.) The resin composition according to claim 1, wherein the polyimide precursor further has a structural unit represented by the following general formula (3).

(In General Formula (3), D is a tetravalent organic group represented by the following General Formula (4).
B, R ¹ and R ² are the same as in the general formula (1), respectively. )

(In General Formula (4), Z is an ether bond (—O—).)   The resin composition according to claim 1 or 2, wherein the polyimide precursor is a polyimide precursor having 50 mol% or more of the structural unit represented by the general formula (1) with respect to all the structural units.   Furthermore, the resin composition in any one of Claims 1-3 containing (b) the compound which generate | occur | produces a radical by irradiation of actinic light, and (c) solvent.   The cured film obtained by heating the resin composition in any one of Claims 1-4. Applying the resin composition according to any one of claims 1 to 4 on a substrate and drying to form a coating film;
Irradiating an actinic ray to the formed coating film and exposing it in a pattern,
A method for producing a patterned cured film, comprising: removing a non-exposed portion other than the exposed portion by development to obtain a patterned resin film; and heating the pattern resin film.   The semiconductor device which has a pattern cured film obtained with the manufacturing method of the pattern cured film of Claim 6.