WO2025204795A1 - Photosensitive resin composition and cured film thereof, and interlayer insulating film and semiconductor protective film using said cured film - Google Patents

Abstract

The present invention addresses the problem of providing: a photosensitive resin composition which, when used to form a film-like shape, exhibits high opening properties and excellent uniformity when an opening pattern is formed by exposure, development, and curing; a cured film obtained by curing a film of the photosensitive resin composition; and an interlayer insulating film or a semiconductor protective film using the cured film. In order to solve the problem, provided is a photosensitive resin composition containing: at least a resin selected from the group consisting of polyimide, polybenzoxazole, polyamide, precursors thereof, and copolymers thereof; a resin selected from the group consisting of a phenolic resin and polyhydroxystyrene; and a photosensitizer, wherein a resin film obtained by applying the photosensitive resin composition to a substrate and subjecting the same to heat treatment exhibits a phase-separated structure.

Description

Photosensitive resin composition and cured film thereof, and interlayer insulating film and semiconductor protective film using the cured film

The present invention relates to a photosensitive resin composition, a cured film obtained from the photosensitive resin composition, and an interlayer insulating film and a semiconductor protective film using the cured film.

Polyimide resins and polybenzoxazole resins, which have excellent heat resistance and mechanical properties, are widely used for surface protection films and interlayer insulating films on semiconductor elements in electronic devices.

When polyimide is used as a surface protection film or interlayer insulating film for semiconductor elements, one method of forming through holes is to use a positive photoresist and perform etching using the photoresist as a mask to form the through holes. However, this method involves the application and removal of photoresist, which is a cumbersome process. Therefore, heat-resistant materials that are also photosensitive have been investigated with the aim of streamlining the process.

As photosensitive materials, materials using quinone diazide compounds as photosensitizers have been proposed, and as a method of increasing sensitivity, systems in which novolac resin or polyhydroxystyrene resin is added to heat-resistant resin have been proposed (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2005-352004

However, when heat-resistant resin and novolac resin are mixed, the resins have low compatibility with each other, resulting in a large degree of phase separation when formed into a film, which can lead to uneven pattern openings within the wafer surface during pattern processing on a silicon wafer.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a photosensitive resin composition in film form that exhibits high opening properties and excellent uniformity when exposed to light, developed, and cured to form an opening pattern, a cured film made from the composition, and an interlayer insulating film or semiconductor protective film made from the composition.

In order to solve the above problems, the photosensitive resin composition of the present invention has the following configuration. That is, it is a photosensitive resin composition containing at least a resin selected from the group consisting of polyimide, polybenzoxazole, polyamide, and precursors and copolymers thereof, a resin selected from the group consisting of phenolic resin and polyhydroxystyrene, and a photosensitizer, and the photosensitive resin composition is applied to a substrate and heat-treated to produce a resin film that exhibits a phase-separated structure.

The present invention also relates to a cured film obtained by curing a film of the photosensitive resin composition, and to an interlayer insulating film or semiconductor protective film using the cured film.

The present invention makes it possible to obtain a photosensitive resin composition that is highly sensitive, has a film-like structure, and exhibits high opening properties when exposed to light, developed, and cured to form an opening pattern, while also exhibiting excellent pattern uniformity.

The present invention relates to a photosensitive resin composition that contains at least a resin selected from the group consisting of polyimide, polybenzoxazole, polyamide, and precursors and copolymers thereof (hereinafter, such a resin may be referred to as "resin (A)"), a resin selected from the group consisting of phenolic resin and polyhydroxystyrene (hereinafter, such a resin may be referred to as "resin (B)"), and a photosensitizer, and that is obtained by applying the photosensitive resin composition to a substrate and subjecting it to a heat treatment, resulting in a resin film that exhibits a phase-separated structure.

The photosensitive resin composition of the present invention contains an alkali-soluble resin (resin (A) and/or resin (B)), thereby ensuring solubility in an alkaline developer. Here, an alkali-soluble resin refers to a resin whose film-like resin composition has a dissolution rate of 50 nm/min or more in an alkaline aqueous solution used as a developer. Specifically, a solution of the resin dissolved in gamma-butyrolactone is applied to a silicon wafer, and the wafer is prebaked on a hot plate at 120°C for 4 minutes to form a prebaked film with a thickness of 10 μm±0.5 μm. The prebaked film is then immersed in a 2.38% by mass aqueous solution of tetramethylammonium hydroxide at 23±1°C for 1 minute, followed by rinsing with pure water. The dissolution rate, calculated from the loss in film thickness, is 50 nm/min or more.

The use of resin (A) enables the photosensitive resin composition of the present invention to achieve high heat resistance.

For example, a polyimide precursor can be obtained by reacting a tetracarboxylic acid, the corresponding tetracarboxylic dianhydride, or a tetracarboxylic diester dichloride with a diamine, the corresponding diisocyanate compound, or a trimethylsilylated diamine. A polyimide can be obtained, for example, by dehydrating and cyclizing the polyimide precursor obtained by the above method using heat or a chemical treatment with an acid or base.

Polyamides can be obtained by reacting dicarboxylic acids, the corresponding dicarboxylic dianhydrides, dicarboxylic acid diester dichlorides, etc. with diamines, the corresponding diisocyanate compounds, and trimethylsilylated diamines.

Polybenzoxazole precursors can be obtained by reacting bisaminophenols with dicarboxylic acids, the corresponding dicarboxylic acid chlorides, dicarboxylic acid activated esters, etc. Polybenzoxazole can be obtained, for example, by dehydrating and cyclizing the polybenzoxazole precursor obtained by the above method using heat or chemical treatment with phosphoric anhydride, bases, carbodiimide compounds, etc.

The resin (A) preferably has at least one repeating unit selected from the repeating units shown below.

In the repeating unit, ^X1 represents an acid dianhydride residue, ^X2 represents a tetracarboxylic acid residue or a tricarboxylic acid residue, ^X3 represents a dicarboxylic acid residue, ^Y1 (OH) _p , ^Y2 (OH) _q , and ^Y3 (OH) _r each represent a diamine residue, p, q, and r each represent an integer ranging from 0 to 4, ^R1 represents a hydrogen atom or an organic group having 1 to 10 carbon atoms, and s represents 1 or 2.

Here, examples of organic groups having 1 to 10 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, isopropyl, and tert-butyl groups.

Known compounds can be used as compounds that provide the acid dianhydride residues, tetracarboxylic acid residues, tricarboxylic acid residues, dicarboxylic acid residues, and diamine residues.

In order to improve the storage stability of the resin (A), it is preferable to cap the main chain ends with an end-capping agent such as a monoamine, acid anhydride, monocarboxylic acid, monoacid chloride compound, or monoactive ester compound.

Known monoamines, acid anhydrides, monocarboxylic acids, monoacid chloride compounds, or monoactive ester compounds can be used.

The introduction ratio of the monoamine used as the end-capping agent is preferably 0.1 mol% or more, particularly preferably 5 mol% or more, and preferably 40 mol% or less, particularly preferably 30 mol% or less, when the total amount of diamine and monoamine introduced into the resin is taken as 100 mol%. The introduction ratio of the acid anhydride, monocarboxylic acid, monoacid chloride compound, or monoactive ester compound used as the end-capping agent is preferably 0.1 mol% or more, particularly preferably 5 mol% or more, relative to the diamine component. On the other hand, in order to maintain a high molecular weight of the resin, it is preferably 100 mol% or less, particularly preferably 90 mol% or less. Multiple different end groups may be introduced by reacting multiple end-capping agents.

The amount of end-capping agent corresponding to the end groups introduced into the resin (A) can be detected by the following method. For example, the resin into which the end groups have been introduced is dissolved in an acidic solution, decomposed into the structural units, amine components and acid anhydride components, and then subjected to gas chromatography (GC) or nuclear magnetic resonance (NMR) measurement. Alternatively, the amount of end-capping agent can be detected by directly measuring the resin component into which the end groups have been introduced using pyrolysis gas chromatography (PGC), infrared spectroscopy, and ^C -NMR spectroscopy.

The alkaline dissolution rate (R(A)) of the resin (A) used in the present invention is preferably 100 nm/min or more, more preferably 500 nm/min or more, and even more preferably 1000 nm/min or more, from the viewpoint of shortening the development time; and is preferably 10,000 nm/min or less, more preferably 5,000 nm/min or less, and even more preferably 2,000 nm/min or less, from the viewpoint of improving the pattern shape.

The weight average molecular weight (Mw(A)) of the resin (A) in terms of polystyrene is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 20,000 or more, from the viewpoint of the mechanical properties of the cured film; and preferably 100,000 or less, more preferably 40,000 or less, and even more preferably 34,000 or less, from the viewpoint of alkali solubility. The weight average molecular weight can be determined by gel permeation chromatography (GPC).

The photosensitive resin composition of the present invention contains resin (B), which allows it to achieve high sensitivity when processed into a film.

Examples of resin (B) include novolac resin, resol resin, benzyl ether type phenolic resin, and polyhydroxystyrene, but are not limited to these as long as they are phenolic resin or polyhydroxystyrene. Two or more of these may also be used.

Novolac resins are obtained by polycondensing phenols and aldehydes such as formalin using known methods.

The polyhydroxystyrene used as resin (B) can be obtained, for example, by addition polymerization of a phenol derivative in which an unsaturated double bond is directly bonded to a benzene ring using a known method.

The alkaline dissolution rate (R(B)) of the resin (B) used in the present invention is preferably 500 nm/min or more, more preferably 1000 nm/min or more, and even more preferably 3000 nm/min or more, from the viewpoint of shortening the development time; and is preferably 30,000 nm/min or less, more preferably 20,000 nm/min or less, and even more preferably 15,000 nm/min or less, from the viewpoint of improving the pattern shape.

The weight average molecular weight (Mw(B)) of resin (B) in terms of polystyrene is preferably 500 or more, more preferably 1,000 or more, and even more preferably 2,000 or more, from the viewpoint of chemical resistance; and preferably 40,000 or less, more preferably 10,000 or less, and even more preferably 5,000 or less, from the viewpoint of alkali solubility.

The phase-separated structure referred to in this invention refers primarily to the phase-separated state that occurs when two or more types of polymers are mixed, and can be observed using the following method.

To observe the phase separation structure, a thin film sample approximately 100 nm thick is cut out from a resin film (including resin films after heat treatment and cured films formed by curing such resin films) made from a photosensitive resin composition, and the cross section of the resin film is observed using a transmission electron microscope. Any location within the film thickness can be observed. The observed image is binarized using image analysis software, and a phase separation structure is defined as one in which the area ratio of one of the binarized phases (referred to as "one phase") accounts for 20-70% of the entire image. The specific method for calculating the phase area ratio is as follows:

A cross section of the resin film is observed using a transmission electron microscope at magnifications of 10,000 to 30,000 times. An area equivalent to a film area of 2 μm square is cut out from the resulting image, and the image is converted to 16-bit using the image analysis software "ImageJ," after which the image is smoothed. A Gaussian filter of σ = 2.0 is used. The background of the image is then subtracted. The rolling ball radius is set to 30 pixels. The contrast of the image is then enhanced. The number of saturated pixels is set to 0.35%. The image is then binarized by setting a threshold value using IsoData Auto, and the area ratio of the colored area to the entire image is calculated. Areas where the area ratio of the colored area is 20 to 70% are considered to "exhibit a phase separation structure."

When the area ratio of one phase is in the range of 20-70% of the entire image, the degree of phase separation is appropriate for obtaining the properties of each resin in the polymer blend. The area ratio of one phase is more preferably 25-60% of the entire image, and even more preferably 30-50%. By keeping it in this range, it is possible to effectively obtain the high heat resistance and mechanical properties of resin (A) and the high processing sensitivity of resin (B). Furthermore, since uniform alkali solubility is obtained within the surface during pattern processing, highly uniform pattern opening properties within the surface are obtained, and clouding after development can be suppressed.

Furthermore, as for the phase separation structure, when each individual phase detected in the observation image that has been binarized using the image analysis software, i.e., a unit in the image where one phase is surrounded by other parts (sometimes referred to as an "island domain"), is plotted with the area of each phase on the horizontal axis and the sum of the brightnesses of the detected phases on the vertical axis, the slope a of the approximation equation y = ax + b when the plot is approximated as a straight line is preferably -1.0 to -30.0, more preferably -1.5 to -10.0, and even more preferably -2.0 to -5.0. This range ensures that the size of the phase separation domain in the resin film is optimal for improving heat resistance, mechanical properties, and sensitivity during processing, and also allows for pattern opening with high in-plane uniformity.

The method for calculating the slope a will be explained in more detail. Similar to the method for observing the phase separation structure described above, a thin film sample approximately 100 nm thick is cut out from a resin film made from a photosensitive resin composition, and the cross section of the resin film is observed using a transmission electron microscope. Any location within the film thickness can be observed. A 2 μm square area is cut out from the obtained image, and the image is converted to 32 bits using the image analysis software "ImageJ." Noise is reduced using a Gaussian filter σ = 2.0, and the background is subtracted using a rolling ball radius of 30 pixels. Next, the threshold determination algorithm is set to "Default" and the image is binarized. For areas recognized as black foreground, the area value of the island domain to be analyzed is set to "100 pixels^2 - Infinity" and the sum of brightness (IntDen) is calculated. However, island domains that are not entirely visible in the image are excluded. A scatter diagram of the analysis results is plotted with the X axis representing the area of the island domains (Area) and the Y axis representing the sum of brightness (IntDen). A linear approximation (regression equation using a linear function) is drawn for the plot, and the slope is defined as slope a.

The photosensitive resin composition of the present invention is applied to a substrate and heat-treated to produce a resin film with a phase-separated structure. Application to the substrate can be achieved by spin coating using a spinner, spray coating, roll coating, slit die coating, or other methods. The resin film thickness varies depending on the application method, solids concentration, viscosity, and other factors, but a film thickness of 0.5 to 20 μm after heat treatment is preferred. The heat treatment can be performed immediately after application (pre-baking) or after pattern processing (curing). The photosensitive resin composition of the present invention exhibits a phase-separated structure after pre-baking. The cured film preferably also exhibits a phase-separated structure after curing. Pre-baking is performed using a hot plate at 80 to 150°C for 1 to 30 minutes, preferably at 100 to 130°C for 1 to 5 minutes, with 120°C being particularly preferred. Curing can be performed using an oven, hot plate, infrared, or other methods, and involves applying temperatures of 150 to 400°C to convert the composition into a heat-resistant resin film. This treatment is preferably carried out for 30 minutes to 3 hours by selecting a temperature and increasing the temperature in stages, or by selecting a temperature range and continuously increasing the temperature. When continuously increasing and decreasing the temperature, the temperature increase rate is preferably 1 to 10°C/min, and more preferably 2 to 5°C/min, to obtain a phase-separated structure. The temperature decrease rate is preferably 1 to 10°C/min, and more preferably 2 to 5°C/min. For example, after treating at 150°C for 30 minutes in an oven under a nitrogen atmosphere, the temperature is increased at a rate of 5°C/min, treated at 320°C for 1 hour, and then decreased to 100°C or below at a rate of 4°C/min.

In the photosensitive resin composition of the present invention, since it is easy to achieve a phase-separated structure and the surface roughness and contact angle described below are within preferred ranges, the content of resin (B) is preferably 15 to 200 parts by mass, more preferably 50 to 200 parts by mass, and even more preferably 100 to 150 parts by mass, per 100 parts by mass of resin (A). Furthermore, the ratio of Mw(A) to Mw(B), (Mw(A)/Mw(B)), is preferably 1 to 20, more preferably 5 to 10, and even more preferably 7 to 10.

In the photosensitive resin composition of the present invention, in order to easily achieve a phase-separated structure, all or a portion of the carboxyl group terminals of resin (A) preferably have a structure represented by formula (1) or (2), and the solubility parameter (SP value) of the amine that reacts with the carboxyl group terminals to give the structure represented by formula (1) or (2) is preferably 8.0 to 16.0, more preferably 10.0 to 12.0. The amide or imide group in formula (1) or (2) represents a carbonyl group derived from the carboxyl group terminal. The solubility parameter (SP value) was determined using the value described in "Coating Basic Science" (page 65, Yuji Harasaki, Maki Shoten). For materials not described in the literature, the value calculated from the evaporation energy and molar volume of atoms and atomic groups according to Fedors' method in "Coating Basic Science" (page 55, Yuji Harasaki, Maki Shoten) was used. The resin (A) can be obtained by using, for example, a monoamine as an amine or end-capping agent that reacts with the carboxyl group terminal to give a structure of formula ( ¹ ) or formula (2), in which case R1 or ^R2 represents a monoamine residue. When a monoamine is used as the end-capping agent, the SP value of the monoamine is preferably 8.0 to 16.0, more preferably 10.0 to 12.0. Examples of resin (A) having a terminal represented by formula (1) include polyimide precursors. Examples of resin (A) having a terminal represented by formula (1) include polyimides. Examples of monoamines include aniline, 2-ethynylaniline, 3-ethynylaniline, 4-ethynylaniline, 5-amino-8-hydroxyquinoline, 1-hydroxy-7-aminonaphthalene, 1-hydroxy-6-aminonaphthalene, 1-hydroxy-5-aminonaphthalene, 1-hydroxy-4-aminonaphthalene, 2-hydroxy-7-aminonaphthalene, 2-hydroxy-6-aminonaphthalene, 2-hydroxy-5-aminonaphthalene, 1-carboxy-7-aminonaphthalene, 1-carboxy-6-aminonaphthalene, 1-carboxy-5-aminonaphthalene, and 2-carboxy-7-aminonaphthalene. , 2-carboxy-6-aminonaphthalene, 2-carboxy-5-aminonaphthalene, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 4-aminobenzenesulfonic acid, 3-amino-4,6-dihydroxypyrimidine, 2-aminophenol, 3-aminophenol, 4-aminophenol, 2-aminothiophenol, 3-aminothiophenol, 4-aminothiophenol, 2-amino-4-tert-butylphenol, etc. can be used. Among these, aniline, 2-ethynylaniline, 3-ethynylaniline, 4-ethynylaniline, and 2-amino-4-tert-butylphenol are preferred. Two or more of these may be used.

In formula (1), R ¹ represents a monovalent organic group having 1 to 20 carbon atoms, and * represents the point of attachment to a dicarboxylic acid residue, a tricarboxylic acid residue, or a tetracarboxylic acid residue.

In formula (2), ^R2 represents a monovalent organic group having 1 to 20 carbon atoms, and * represents the point of attachment to a dicarboxylic acid residue, tricarboxylic acid residue, or tetracarboxylic acid residue.

Monovalent organic groups having 1 to 20 carbon atoms include, for example, branched or straight-chain alkyl groups, alkylene groups, and alkyne groups, all of which have a total carbon number of 1 to 20, and also include those in which some of the hydrogen atoms have been substituted with oxyalkyl groups, thioalkyl groups, cyano groups, or halogen groups.

The photosensitive resin composition of the present invention preferably has a difference (Ra(2) - Ra(1)) between the surface roughness (Ra(1)) of a resin film obtained by applying the photosensitive resin composition to a substrate and heat-treating it at 120°C for 3 minutes and the surface roughness (Ra(2)) of a film obtained by treating the resin film with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH aqueous solution) at 23°C for 1 minute, of 10 nm or more and 200 nm or less.

Within this range, there is little difference in local alkali solubility during development, pattern opening with high in-plane uniformity can be achieved, and cloudiness after development can be suppressed. From this perspective, (Ra(2) - Ra(1)) is more preferably 20 to 100 nm, and even more preferably 30 to 50 nm.

Furthermore, the photosensitive resin composition of the present invention preferably has a difference (θ(1) - θ(2)) between the static water contact angle (θ(1)) of the surface of a resin film obtained by applying the photosensitive resin composition to a substrate and heat-treating it at 120°C for 3 minutes and the static water contact angle (θ(2)) of the surface of a film obtained by treating the resin film with a 2.38% by mass aqueous solution of TMAH at 23°C for 1 minute, such that the difference is 5° or more and less than 30°, and more preferably 5° or more and less than 20°.

By being in this range, the difference in local alkali solubility during development is small, pattern opening with high in-plane uniformity can be achieved, and cloudiness after development can be suppressed. Furthermore, the difference (θa(1) - θa(2)) between the advancing contact angle of water (θa(1)) on the film before treatment with the TMAH aqueous solution and the advancing contact angle (θa(2)) on the surface of the film after treating the resin film with the TMAH aqueous solution for 1 minute is preferably 5° or more and less than 20°, and more preferably 5° or more and less than 15°. Furthermore, the difference (θr(1) - θr(2)) between the receding contact angle of water (θr(1)) on the surface of the film after treating the resin film with the TMAH aqueous solution for 1 minute at 23°C is preferably 10° to 60°, and more preferably 20° to 35°. By being in this range, the difference in local alkali solubility during development is small, pattern opening with high in-plane uniformity can be achieved, and cloudiness after development can be suppressed.

Furthermore, the ratio (R(B)/R(A)) of the alkaline dissolution rate (R(A)) of resin (A) used in the photosensitive resin composition of the present invention to the alkaline dissolution rate (R(B)) of resin (B) is preferably 2.5 to 30. This range makes it easier to achieve the phase-separated structure described above, and allows the difference in surface roughness (Ra(2) - Ra(1)) and the differences in contact angle (θ(1) - θ(2)), (θa(1) - θa(2)), and (θr(1) - θr(2)) to be within preferred ranges. This results in high opening properties when an opening pattern is formed by exposure, development, and curing, excellent pattern uniformity, and suppression of cloudiness after development. It is even more preferable that (R(B)/R(A)) be 4.0 to 15.

Furthermore, in the photosensitive resin composition of the present invention, resin (A) contains carboxyl groups and esterified carboxyl groups, and the ratio of esterified carboxyl groups to the total amount of carboxyl groups and esterified carboxyl groups (100 mol%) is preferably 50 to 80 mol%, and more preferably 60 to 75 mol%. This range allows the alkali dissolution rate of resin A to be within a preferred range, and the difference in surface roughness (Ra(2) - Ra(1)) and the difference in contact angle (θ(1) - θ(2)), (θa(1) - θa(2)), and (θr(1) - θr(2)) can be within preferred ranges. This results in high opening properties when an opening pattern is formed by exposure, development, and curing, excellent pattern uniformity, and suppressed cloudiness after development. One method for obtaining esterified carboxyl groups is to dropwise add a diluted solution of an esterifying agent such as N,N-dimethylformamide dimethyl acetal, N,N-dimethylformamide diethyl acetal, or N,N-dimethylacetamide dimethyl acetal to a solution of a resin containing carboxyl groups during resin polymerization.

The photosensitive resin composition of the present invention contains a photosensitizer. A quinone diazide compound is preferably used as the photosensitizer. By including a quinone diazide compound in the photosensitive resin composition of the present invention, acid is generated in the ultraviolet-exposed areas, increasing the solubility of the exposed areas in an alkaline aqueous solution. Therefore, a positive-tone pattern can be obtained by alkaline development after ultraviolet exposure.

The content of the photosensitizer used in the present invention is preferably 1 part by mass or more, more preferably 3 parts by mass or more, per 100 parts by mass of resin (A) in order to achieve high sensitivity, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, in order to maintain the mechanical properties of the cured film. Furthermore, a sensitizer or the like may be contained as necessary.

Examples of quinone diazide compounds include those in which the sulfonic acid of quinone diazide is ester-bonded to a polyhydroxy compound, those in which the sulfonic acid of quinone diazide is sulfonamide-bonded to a polyamino compound, and those in which the sulfonic acid of quinone diazide is ester-bonded and/or sulfonamide-bonded to a polyhydroxypolyamino compound. While not all functional groups of these polyhydroxy compounds or polyamino compounds need to be substituted with quinone diazide, it is preferable that 50 mol% or more of all functional groups are substituted with quinone diazide. By using such quinone diazide compounds, a positive-tone photosensitive resin composition can be obtained that is sensitive to common ultraviolet rays, such as the i-line (365 nm), h-line (405 nm), and g-line (436 nm) of a mercury lamp.

In the present invention, the quinone diazide compound preferably has either a 5-naphthoquinone diazide sulfonyl group or a 4-naphthoquinone diazide sulfonyl group. A compound having both of these groups in the same molecule may be used, or compounds using different groups may be used in combination.

Furthermore, two or more types of quinone diazide compounds may be contained. This makes it possible to increase the ratio of the dissolution rates of exposed and unexposed areas, resulting in a highly sensitive positive-tone photosensitive resin composition.

The quinone diazide compound is particularly preferably the compound shown below.

In formula (3), Q is a structure represented by formula (4) or a hydrogen atom, and in formula (4), * represents the point of attachment to the structure of formula (3).

When the total amount of Q is taken as 100 mol%, it is preferable that the structure represented by formula (4) accounts for 90 to 100 mol%. Furthermore, out of a total of 100 mol% of the quinone diazide compound of formula (3), when the molar ratio of all Q's where all are hydrogen atoms is a(0), the molar ratio of one Q where one of the Q's has a structure represented by formula (4) is a(1), the molar ratio of two Q's where two of the Q's have a structure represented by formula (4) is a(2), and the molar ratio of all Q's where all of the Q's have a structure represented by formula (4) is a(3), it is preferable that a(0) is 0 to 15 mol%, a(1) is 0 to 5 mol%, a(2) is 10 to 20 mol%, and a(3) is 80 to 90 mol%. This range minimizes the difference in partial alkali solubility during development, resulting in high opening properties when an opening pattern is formed by exposure, development, and curing, and also ensures excellent pattern uniformity and suppresses cloudiness after development.

The quinone diazide compound used in the present invention can be synthesized by known methods. For example, one method involves reacting 5-naphthoquinone diazide sulfonyl chloride with a polyhydroxy compound in the presence of triethylamine.

The photosensitive resin composition of the present invention is applied to a substrate and heat-treated to produce a resin film that exhibits a phase-separated structure.

The photosensitive resin composition of the present invention preferably further contains a compound represented by any one of formulas (5) to (10) (hereinafter sometimes referred to as "compound (C)").

In formula (5), ^R3 represents a hydrogen atom, a hydroxyl group, or a monovalent organic group having 1 to 10 carbon atoms; ^R4 and ^R5 each independently represent a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms; and ^R6 and ^R7 each independently represent a monovalent organic group having 1 to 4 carbon atoms.

In formula (6), R ⁸ represents a monovalent organic group having 1 to 6 carbon atoms, and R ⁹ and R ¹⁰ each independently represent a monovalent organic group having 1 to 4 carbon atoms.

In formula (7), R ¹¹ and R ¹² each independently represent a monovalent organic group having 1 to 10 carbon atoms.

In formula (8), R ¹³ to R ¹⁶ each independently represent a monovalent organic group having 1 to 4 carbon atoms.

In formula (9), R ¹⁷ and R ¹⁸ each independently represent a monovalent organic group having 1 to 4 carbon atoms; m is 1 or 2.

In formula (10), R ¹⁹ and R ²⁰ each independently represent a monovalent organic group having 1 to 4 carbon atoms.

In the above formulas (5) to (10), the monovalent organic group includes, for example, branched or straight-chain alkyl groups, alkylene groups, and alkyne groups, each having a total carbon number within the range indicated for that group, and also includes groups in which some of the hydrogen atoms have been substituted with oxyalkyl groups, thioalkyl groups, cyano groups, or halogen groups.

The inclusion of compound (C) in the photosensitive resin composition of the present invention improves the storage stability of the photosensitive resin composition, stabilizes the size of the phase-separated structure in the photosensitive resin composition against changes over time, and enables the resin film obtained by coating and heat treatment to have a highly uniform continuous phase in the phase-separated structure, i.e., a film in which the width of the continuous phase is small and has little width variation when photographed in a cross-section. The content of compound (C) is preferably 0.1 to 1 mass% when the total mass of the photosensitive resin composition is taken as 100 mass%, or preferably 0.1 to 1 mass% when the total mass of resin (A), resin (B), and compound (C) is taken as 100 mass%. A content of 0.1 parts by mass or more is advantageous in terms of stabilizing the size of the phase-separated structure against changes over time, while a content of 1 part by mass or less suppresses an excessive increase in the alkali solubility of the unexposed portions of the photosensitive resin composition after the exposure step, achieving highly uniform pattern opening properties within the surface and suppressing cloudiness after development.

Examples of compounds represented by formula (5) include, but are not limited to, N,N-dimethylpropanamide, N,N-dimethylisobutyramide, N,N-dimethylbutanamide, 2-methyl-N,N-dimethylbutanamide, N,N-dimethylpentanamide, N,N-dimethylisobutyramide, 2-methoxy-N,N-dimethylethanamide, 2-ethoxy-N,N-dimethylethanamide, 2-propoxy-N,N-dimethylethanamide, and 2-butoxy-N,N-dimethylethanamide.

Examples of compounds represented by formula (6) include, but are not limited to, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy-N,N-dimethylpropanamide, 3-propoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 3-methoxy-N,N-diethylpropanamide, and 3-methoxy-N,N-dipropylpropanamide.

Examples of compounds represented by formula (7) include, but are not limited to, 3-methoxy-3-methylbutyl acetate and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

Examples of compounds represented by formula (8) include, but are not limited to, N,N,N',N'-tetramethylurea, N,N,N',N'-tetraethylurea, and N,N-diethyl-N',N'-dimethylurea.

Examples of compounds represented by formula (9) include, but are not limited to, N,N-dimethylpropylene urea, N,N-diethylpropylene urea, N,N-dipropylpropylene urea, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, and 1,3-dipropyl-2-imidazolidinone.

Examples of compounds represented by formula (10) include, but are not limited to, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, and diisobutyl ketone.

The photosensitive resin composition of the present invention may contain a thermal crosslinking agent as needed. Preferred thermal crosslinking agents include, but are not limited to, compounds having at least two alkoxymethyl groups and/or methylol groups, and compounds having at least two epoxy groups and/or oxetanyl groups. The inclusion of these compounds causes a condensation reaction with resin (A) during the curing process after pattern processing, resulting in a crosslinked structure, improving the mechanical properties of the cured film. Two or more types of thermal crosslinking agents may also be used, allowing for an even wider range of designs.

Preferred examples of compounds having at least two alkoxymethyl groups and/or methylol groups include, for example, DML-PC, DML-PEP, DML-OC, DML-OEP, DML-34X, DML-PTBP, DML-PCHP, DML-OCHP, DML-PFP, DML-PSBP, DML-POP, DML-MBOC, DML-MBPC, DML-MTrisPC, DML-BisOC-Z, DML-BisOCHP-Z, DML-BPC, DML-BisOC-P, DMOM-PC, DMOM-PTBP, DMOM-MBPC, TriML-P, TriML-35XL, TML-HQ, TML-BP, and TML-pp. -BPF, TML-BPE, TML-BPA, TML-BPAF, TML-BPAP, TMOM-BP, TMOM-BPE, TMOM-BPA, TMOM-B PAF, TMOM-BPAP, HML-TPPHBA, HML-TPHAP, HMOM-TPPHBA, HMOM-TPHAP (all product names, Honshu Chemical Industries ( Examples of such compounds include "NIKALAC" (registered trademark) MX-290, NIKALAC MX-280, NIKALAC MX-270, NIKALAC MX-279, NIKALAC MW-100LM, and NIKALAC MX-750LM (all trade names manufactured by Sanwa Chemical Co., Ltd.), which are available from the respective companies. Two or more of these compounds may be used together.

Furthermore, preferred examples of compounds having at least two epoxy groups and/or oxetanyl groups include, but are not limited to, bisphenol A type epoxy resin, bisphenol A type oxetanyl resin, bisphenol F type epoxy resin, bisphenol F type oxetanyl resin, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polymethyl(glycidyloxypropyl)siloxane, and other epoxy group-containing silicones. Specifically, "EPICLON" (registered trademark) 850-S, EPICLON HP-4032, EPICLON HP-7200, EPICLON HP-820, EPICLON HP-4700, EPICLON EXA-4710, EPICLON HP-4770, EPICLON EXA-859CRP, EPICLON EXA-1514, EPICLON EXA-4880, EPICL Examples of such resins include ON EXA-4850-150, EPICLON EXA-4850-1000, EPICLON EXA-4816, and EPICLON EXA-4822 (all trade names, manufactured by Dainippon Ink and Chemicals, Inc.), "RIKARESIN" (registered trademark) BEO-60E (trade name, manufactured by New Japan Chemical Co., Ltd.), and EP-4003S and EP-4000S (trade names, manufactured by ADEKA Corporation), all of which are available from various companies. Two or more of these may be used.

The content of the thermal crosslinking agent used in the present invention is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of resin (A). From the viewpoint of maintaining mechanical properties such as elongation, the content is preferably 300 parts by mass or less, more preferably 200 parts by mass or less.

The photosensitive resin composition of the present invention may contain a solvent, if necessary. Preferred examples of solvents include polar aprotic solvents such as N-methyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide; ethers such as tetrahydrofuran, dioxane, propylene glycol monomethyl ether, and propylene glycol monoethyl ether; ketones such as acetone, methyl ethyl ketone, and diisobutyl ketone; esters such as ethyl acetate, butyl acetate, isobutyl acetate, propyl acetate, propylene glycol monomethyl ether acetate, and 3-methyl-3-methoxybutyl acetate; alcohols such as ethyl lactate, methyl lactate, diacetone alcohol, and 3-methyl-3-methoxybutanol; and aromatic hydrocarbons such as toluene and xylene. Two or more of these may be contained.

The content of the solvent is preferably 70 parts by mass or more, more preferably 100 parts by mass or more, per 100 parts by mass of resin (A), from the viewpoint of resin dissolution, and is preferably 1,800 parts by mass or less, more preferably 1,500 parts by mass or less, from the viewpoint of obtaining an appropriate film thickness.

The photosensitive resin composition of the present invention may contain a low molecular weight compound having a phenolic hydroxyl group, if necessary. The inclusion of a low molecular weight compound having a phenolic hydroxyl group makes it easier to adjust the alkali solubility during pattern processing.

The content of the low molecular weight compound having a phenolic hydroxyl group is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of resin (A); from the viewpoint of maintaining mechanical properties such as elongation, it is preferably 30 parts by mass or less, more preferably 15 parts by mass or less.

The photosensitive resin composition of the present invention may contain surfactants, esters such as ethyl lactate and propylene glycol monomethyl ether acetate, alcohols such as ethanol, ketones such as cyclohexanone and methyl isobutyl ketone, and ethers such as tetrahydrofuran and dioxane, if necessary, to improve wettability with the substrate. Some of these can also serve as solvents.

The preferred content of the compound used to improve wettability with the substrate is 0.001 parts by mass or more per 100 parts by mass of resin (A), and from the perspective of obtaining an appropriate film thickness, it is preferably 1,800 parts by mass or less, and more preferably 1,500 parts by mass or less.

In addition, to improve adhesion to silicon substrates, a silane coupling agent such as trimethoxyaminopropylsilane, trimethoxyepoxysilane, trimethoxyvinylsilane, or trimethoxythiolpropylsilane may be included.

The preferred content of these compounds used to improve adhesion to silicon substrates is 0.01 parts by mass or more per 100 parts by mass of resin (A), and from the perspective of maintaining mechanical properties such as elongation, it is preferably 5 parts by mass or less.

The viscosity of the photosensitive resin composition of the present invention is preferably 2 to 5,000 mPa·s. By adjusting the solids concentration so that the viscosity is 2 mPa·s or higher, it becomes easier to obtain the desired film thickness. On the other hand, if the viscosity is 5,000 mPa·s or lower, it becomes easier to obtain a highly uniform coating film. A photosensitive resin composition with such a viscosity can be easily obtained, for example, by adjusting the solids concentration to 5 to 60 mass%.

Next, we will explain a method for forming a cured film using the photosensitive resin composition of the present invention.

The photosensitive resin composition of the present invention is applied to a substrate. Substrates that can be used include, but are not limited to, wafers of silicon, ceramics, gallium arsenide, etc., or substrates on which metals are formed as electrodes or wiring. Application methods include spin coating using a spinner, spray coating, and roll coating. The coating thickness varies depending on the application method, the solids concentration of the composition, viscosity, etc., but is typically applied so that the film thickness after drying is 0.5 to 20 μm.

Next, the substrate coated with the photosensitive resin composition is heat-treated (pre-baked) to obtain a resin film of the photosensitive resin composition. Pre-baking is preferably performed using a hot plate at a temperature range of 80-150°C for 1-30 minutes, or on a hot plate at 100-130°C for 1-5 minutes.

When forming a resin pattern using this photosensitive resin composition, the film of this photosensitive resin composition is then exposed to actinic radiation through a mask having the desired pattern. Actinic radiation used for exposure includes ultraviolet light, visible light, electron beams, and X-rays, but in the present invention, the i-line (365 nm), h-line (405 nm), and g-line (436 nm) from a mercury lamp are preferably used.

The exposure may be performed using a half-tone mask, or by performing multiple exposures with different exposure locations, masks, and exposure amounts, for example, so that the exposure amount varies depending on the exposure location on the substrate.

After exposure, the film is developed using a developer. Preferred developer solutions include aqueous solutions of alkaline compounds such as tetramethylammonium hydroxide, diethanolamine, diethylaminoethanol, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, diethylamine, methylamine, dimethylamine, dimethylaminoethyl acetate, dimethylaminoethanol, dimethylaminoethyl methacrylate, cyclohexylamine, ethylenediamine, and hexamethylenediamine. In some cases, these alkaline aqueous solutions may contain polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, γ-butyrolactone, and dimethylacrylamide; alcohols such as methanol, ethanol, and isopropanol; esters such as ethyl lactate and propylene glycol monomethyl ether acetate; and ketones such as cyclopentanone, cyclohexanone, isobutyl ketone, and methyl isobutyl ketone, either singly or in combination. After development, it is preferable to rinse with water. Here too, alcohols such as ethanol and isopropyl alcohol, or esters such as ethyl lactate and propylene glycol monomethyl ether acetate may be added to the water for rinsing.

After pre-baking, or after forming a resin pattern using the method described above, it is preferable to apply a temperature of 150 to 400°C to promote thermal crosslinking, imide ring-closing reaction, and oxazole ring-closing reaction and harden the film, thereby improving the heat resistance and chemical resistance of the cured film. This heat treatment (cure) is preferably carried out by selecting a temperature and increasing the temperature in stages, or by selecting a temperature range and increasing the temperature continuously for 30 minutes to 3 hours.

When the surface roughness of the cured film is Ra(3) and the surface roughness of the film obtained by oxygen plasma treatment of the cured film is Ra(4), the difference between them (Ra(4) - Ra(3)) is preferably 10 nm or more and 200 nm or less. The oxygen plasma treatment is performed using a plasma etching device under the following conditions: gas type: oxygen, gas pressure: 20 Pa, gas flow rate: 100 sccm, power: 200 W, time: 60 seconds, temperature: 25°C. Having (Ra(4) - Ra(3)) in this range ensures highly uniform pattern opening across the surface and suppresses clouding of the film surface due to plasma treatment. It is more preferable that (Ra(4) - Ra(3)) is 10 nm or more and 50 nm or less, and even more preferable that it is 10 nm or more and 30 nm or less.

Cured films formed from the photosensitive resin composition of the present invention are suitable for use as passivation films for semiconductors, protective films for semiconductor elements, interlayer insulating films for multilayer wiring used in high-density packaging, and insulating layers for organic electroluminescent devices.

The present invention will be explained below using examples, but the present invention should not be construed as being limited to these examples. First, the evaluation method will be explained. When evaluating the photosensitive resin composition (hereinafter sometimes referred to as "varnish"), it was first filtered through a 1 μm polytetrafluoroethylene filter before use.

(1) Film Thickness Measurement The film thickness of the resin film on the substrate was measured using an optical interference film thickness measuring device (Lambda Ace VM-1030 manufactured by Dainippon Screen Mfg. Co., Ltd.). The refractive index was set to 1.629.

(2) Measurement of Alkaline Dissolution Rate of Resin A resin was dissolved in γ-butyrolactone (GBL) at a solids concentration of 35% by mass, and the solution was applied to a 6-inch silicon wafer and prebaked on a hot plate at 120°C for 4 minutes to form a prebaked film with a film thickness of 10 μm±0.5 μm. This was then immersed in a 2.38% by mass aqueous solution of tetramethylammonium hydroxide at 23°C for 1 minute, and the dissolved film thickness was calculated from the film thickness before and after immersion, and the film thickness dissolved per minute was taken as the alkaline dissolution rate. Note that when the resin film completely dissolved in less than 1 minute, the time required for dissolution was measured, and the film thickness calculated from this and the film thickness before immersion was used to calculate the film thickness dissolved per minute, which was taken as the alkaline dissolution rate of the resin.

(3) Measurement of Weight Average Molecular Weight Using a gel permeation chromatography (GPC) apparatus (Waters 2690-996 manufactured by Japan Waters K.K.), the resin was measured using N-methyl-2-pyrrolidone (NMP) as a developing solvent, and the weight average molecular weight (Mw) was calculated in terms of polystyrene.

(4) Measurement of Esterification Rate The resin was dissolved in deuterated dimethyl sulfoxide and measured using ^1H NMR. The esterification rate (%) was calculated as {(x/100)÷(z/y)}×100, where x is the integral of the peak near 3.8 ppm when the integral of the entire aromatic peak from 6.0 to 9.0 ppm is taken as 100, z is the amount of hydrogen in the ester group when a unit weight (e.g., 1 g) of resin is completely esterified, and y is the number of aromatic ring hydrogen atoms contained in the same weight of resin.

(5) Evaluation of Pattern Processability The varnish was applied to an 8-inch silicon wafer by spin coating using a coating and developing apparatus (ACT-8 manufactured by Tokyo Electron Limited), followed by pre-baking at 120°C for 3 minutes to form a pre-baked film (resin film) with a film thickness of 6 to 8 μm. A mask having a 5 μm-wide line and space pattern was set in an i-line stepper exposure apparatus (NSR-2005i9C manufactured by Nikon Corporation), and the pre-baked film was exposed to an exposure dose of 10 to 500 mJ/ ^cm2 in 10 mJ/ ^cm2 steps. After exposure, the ACT-8 developing apparatus was used to develop the wafer using a 2.38% by mass aqueous solution of tetramethylammonium hydroxide by the puddle method, with the developer discharge time being 5 seconds and the puddle time being 35 seconds, which was repeated twice. The wafer was then rinsed with pure water and then shaken off and dried to obtain a developed film. The silicon wafer with the developed film was cured in a clean oven (CLH-21CD-S manufactured by Koyo Thermo Systems Co., Ltd.) under a nitrogen stream (oxygen concentration of 20 ppm or less) at 150°C for 30 minutes, and then further heated to 320°C for 1 hour. When the temperature reached 50°C or less, the silicon wafer was removed and a cured film (hardened film) was obtained.

The minimum exposure dose (Eth) at which a 5 μm wide pattern was opened was rated A when it was 10 mJ/cm ² or more and less than 100 mJ/cm ² , B when it was 100 mJ/cm ² or more and less than 150 mJ/cm ² , C when it was 150 mJ/cm ² or more and less than 200 mJ/cm ² , and D when it was 200 mJ/cm ² or more.

(6) Evaluation of in-plane uniformity of pattern 50 mJ/ ^cm2 was added to the smallest exposure dose at which the pattern opened in (5) to determine the exposure dose used in this evaluation (evaluation exposure dose). The same procedure as in (5) was followed, except that the exposure dose was fixed at the evaluation exposure dose, and pattern processing was performed by exposing nine points at ±80 mm from the wafer center, ±60 mm from the wafer center, ±40 mm from the wafer center, ±20 mm from the wafer center, and the wafer center, to obtain a cured film (hardened film).

A digital microscope was used to measure the opening dimensions of the pattern in the direction perpendicular to the lines in the 5 μm wide line and space area, and the range of opening dimensions (maximum value - minimum value) at nine points was determined. Opening dimension ranges of less than 0.07 μm were rated A, 0.07 μm or greater but less than 0.1 μm were rated B, 0.1 μm or greater but less than 0.5 μm were rated C, and 0.5 μm or greater were rated D.

(7) Evaluation of phase separation 1
A 100 nm-thick thin film sample was sampled from the prebaked film obtained in (5) using a focused ion beam (FIB) processing and observation device (Hitachi High-Tech FB-2000), and the cross section of the film was observed at an accelerating voltage of 200 kV using a transmission electron microscope (JEOL JEM-F200). A 2 μm square area was cut out from the obtained image, and the observed image was converted to 16-bit using the image analysis software "ImageJ", after which the image was smoothed. At this time, a Gaussian filter σ = 2.0 was used. Next, the image background was subtracted. A rolling ball radius = 30 pixels. Next, the image contrast was enhanced. The number of saturated pixels = 0.35%. Next, a threshold was set using IsoData Auto, and the area ratio of the colored area to the entire image was calculated as the phase separation area ratio. Those with an area ratio of 30 to 50% were designated A, those excluding A and with an area ratio of 20 to 70% were designated B, and the rest were designated C.

Furthermore, for the developed films obtained in (5), those with no cloudiness in the unexposed areas were rated A, those with slight cloudiness were rated B, and those with obvious cloudiness were rated C.

(8) Evaluation of phase separation 2 (slope a)
A 2 μm square region was cut out from the image obtained in (7), and the image was converted to 32 bits using the image analysis software "ImageJ." Noise was reduced using a Gaussian filter σ = 2.0, and background subtraction was performed using a rolling ball radius of 30 pixels. Next, the image was binarized using the Default threshold determination algorithm. For areas recognized as black foreground (of which, units in the image in which one phase is surrounded by other parts are referred to as "island domains"), the area value of the island domain to be analyzed was set to "100 pixels^2 - Infinity," and the sum of brightness (IntDen) was calculated. However, island domains that were not entirely visible in the image were excluded. A scatter diagram of the analysis results was plotted with the area of the island domain (Area) on the X axis and the sum of brightness (IntDen) on the Y axis. A linear approximation curve of the plot was drawn, and its slope was designated as slope a.

A was assigned to slopes a between -2.0 and -5.0, B to slopes a between -1.5 and -10.0 (excluding A), C to slopes a between -1.0 and -30.0 (excluding A and B), and D to slopes other than A.

(9) Surface roughness evaluation 1 (Ra(2)-Ra(1))
Using an AFM (Dimension Icon manufactured by Bruker), the measurement range was 500 nm square, the aspect ratio was 2.00, and the measurement speed was 1.00 Hz, and the height difference of the resin film surface obtained in (5) was measured, and the difference between the maximum height and the minimum height was taken as the surface roughness Ra(1). Similarly, the surface roughness of the developed film surface obtained in (5) was taken as Ra(2), and (Ra(2) - Ra(1)) was calculated.

(Ra(2) - Ra(1)) was rated A when it was between 30 and 50 nm, B when it was between 20 and 100 nm (excluding A), and C when it was between 10 and 200 nm (excluding A and B).

(10) Evaluation of Contact Angle For the prebaked film obtained in (5), the static contact angle θ(1), the advancing contact angle θa(1), and the receding contact angle θr(1) of water were measured. Similarly, for the developed film, the static contact angle θ(2), the advancing contact angle θa(2), and the receding contact angle θr(2) of water were measured.
(θ(1)-θ(2)) was rated as A when it was 5° or more and less than 20°, B when it was 20° or more and less than 30°, and C when it was 30° or more. There were no other values.
(θa(1)-θa(2)) was rated as A when it was 5° or more and less than 15°, B when it was 15° or more and less than 20°, and C when it was 20° or more. There were no other values.
Those where (θr(1)-θr(2)) was 20° to 35° were designated A, those excluding A and 10° to 60° were designated B, and the rest were designated C.

(11) Evaluation of phase separation 3
The phase separation area ratio was calculated in the same manner as in "(7) Evaluation of Phase Separation 1," except that the cured film obtained in (5) was used instead of the prebaked film obtained in (5). Area ratios of 30 to 50% were classified as A, those excluding A and 20 to 70% were classified as B, and all other areas were classified as C.

(12) Surface roughness evaluation 2 (Ra(4)-Ra(3))
The surface roughness (Ra(3)) of the cured film obtained in (5) was determined using the same method as described in "(9) Surface Roughness Evaluation 1". Next, the cured film was treated using a plasma etching device (device name) under the following conditions: gas type: oxygen, gas pressure: 20 Pa, gas flow rate: 100 sccm, power: 200 W, time: 60 seconds, temperature: 25°C, and the surface roughness (Ra(4)) after treatment was measured. Those where (Ra(4) - Ra(3)) was 10 to 30 nm were rated A, those where it was 10 to 50 nm except for A were rated B, and all others were rated C.

Synthesis Example 1 Synthesis of Diamine Compound 1 164.8 g (0.45 mol) of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (BAHF) was dissolved in 900 mL of acetone and 156.8 g (2.7 mol) of propylene oxide, and the solution was cooled to −15° C. To this solution, a solution of 183.7 g (0.99 mol) of 3-nitrobenzoyl chloride dissolved in 900 mL of acetone was added dropwise. After completion of the dropwise addition, the mixture was reacted at −15° C. for 4 hours and then returned to room temperature. The precipitated white solid was filtered and dried in vacuo at 50° C.

270 g of the solid was placed in a 3 L stainless steel autoclave and dispersed in 2400 mL of methyl cellosolve, and 5 g of 5% palladium-carbon was added. Hydrogen was then introduced using a balloon, and the reduction reaction was carried out at room temperature. After 2 hours, the reaction was terminated when it was confirmed that the balloon no longer deflated. After the reaction was complete, the palladium compound catalyst was removed by filtration, and the mixture was concentrated using a rotary evaporator to obtain diamine compound 1 represented by the following formula.

Synthesis Example 2 Synthesis of Resin (A-1) Under a dry nitrogen stream, 62.04 g (0.20 mol) of bis(3,4-dicarboxyphenyl)ether dianhydride (ODPA) was dissolved in 630 g of NMP. To this solution, 96.72 g (0.16 mol) of diamine compound 1 and 2.49 g (0.01 mol) of 1,3-bis(3-aminopropyl)tetramethyldisiloxane were added along with 20 g of NMP, and the mixture was allowed to react at 20°C for 1 hour, followed by a reaction at 50°C for 2 hours. Next, 4.69 g (0.04 mol) of 4-ethynylaniline as an end-capping agent was added along with 10 g of NMP, and the mixture was allowed to react at 50°C for 2 hours. Thereafter, a solution prepared by diluting 38.13 g (0.32 mol) of N,N-dimethylformamide dimethyl acetal with 80 g of NMP was added dropwise over 10 minutes. After the dropwise addition, the mixture was stirred at 50°C for 3 hours. After stirring, the solution was cooled to room temperature and then poured into 5 L of water to obtain a precipitate. The precipitate was collected by filtration, washed three times with water, and then dried in a vacuum dryer at 80°C for 20 hours to obtain a powder of resin (A-1).

Synthesis Example 3 Synthesis of Resin (A-2) Resin (A-2) powder was obtained in the same manner as in Synthesis Example 2, except that the amount of N,N-dimethylformamide dimethyl acetal was 40.51 g (0.34 mol).

Synthesis Example 4 Synthesis of Resin (A-3) Resin (A-3) powder was obtained in the same manner as in Synthesis Example 2, except that the amount of N,N-dimethylformamide dimethyl acetal was 44.09 g (0.37 mol).

Synthesis Example 5 Synthesis of Resin (A-4) A powder of Resin (A-4) was obtained in the same manner as in Synthesis Example 2, except that the amount of Diamine Compound 1 was 99.14 g (0.164 mol) and the amount of N,N-dimethylformamide dimethyl acetal was 40.51 g (0.34 mol).

Synthesis Example 6 Synthesis of Resin (A-5) A powder of Resin (A-5) was obtained in the same manner as in Synthesis Example 2, except that the amount of Diamine Compound 1 was 102.77 g (0.17 mol) and the amount of N,N-dimethylformamide dimethyl acetal was 40.51 g (0.34 mol).

Synthesis Example 7 Synthesis of Resin (A-6) Resin (A-6) powder was obtained in the same manner as in Synthesis Example 2, except that 4-ethynylaniline was replaced with 4.37 g (0.04 mol) of 3-aminophenol and the amount of N,N-dimethylformamide dimethyl acetal was changed to 35.75 g (0.30 mol).

Synthesis Example 8 Synthesis of Resin (A-7) Resin (A-7) powder was obtained in the same manner as in Synthesis Example 2, except that the amount of 4-ethynylaniline and 3-aminophenol was 4.37 g (0.04 mol) and the amount of N,N-dimethylformamide dimethyl acetal was 47.66 g (0.40 mol).

Synthesis Example 9 Synthesis of Resin (A-8) Resin (A-8) powder was obtained in the same manner as in Synthesis Example 2, except that the amount of 4-ethynylaniline and 3-aminophenol was 4.37 g (0.04 mol) and the amount of N,N-dimethylformamide dimethyl acetal was 52.43 g (0.44 mol).

Synthesis Example 10 Synthesis of Resin (A-9) Resin (A-9) powder was obtained in the same manner as in Synthesis Example 2, except that the amount of 4-ethynylaniline and 4-aminophenol was 4.37 g (0.04 mol) and the amount of N,N-dimethylformamide dimethyl acetal was 47.66 g (0.40 mol).

Synthesis Example 11 Synthesis of Resin (A-10) Resin (A-10) powder was obtained in the same manner as in Synthesis Example 2, except that the amount of 4-ethynylaniline and 2-amino-4-tert-butylphenol was 6.61 g (0.04 mol) and the amount of N,N-dimethylformamide dimethyl acetal was 40.51 g (0.34 mol).

Synthesis Example 12 Synthesis of Resin (A-11) Under a dry nitrogen stream, 61.53 g (0.168 mol) of BAHF, 2.49 g (0.01 mol) of 1,3-bis(3-aminopropyl)tetramethyldisiloxane, and 4.37 g (0.04 mol) of 3-aminophenol as an end-capping agent were dissolved in 730 g of NMP. 62.04 g (0.20 mol) of ODPA was added to the solution along with 20 g of NMP, and the mixture was reacted at 20°C for 1 hour, and then at 50°C for 4 hours. The mixture was then stirred at 190°C for 5 hours. After stirring, the solution was cooled to room temperature and then poured into 5 L of water to obtain a precipitate. The precipitate was collected by filtration, washed three times with water, and then dried in a vacuum dryer at 80°C for 20 hours to obtain a powder of Resin (A-11).

[Synthesis Example 13] Synthesis of Resin (B-1) Under a dry nitrogen stream, 75.70 g (0.7 mol) of m-cresol, 21.63 g (0.2 mol) of p-cresol, 12.22 g (0.1 mol) of 2,5-dimethylphenol, 75.5 g of a 37% by mass aqueous formaldehyde solution (0.93 mol of formaldehyde), 0.63 g (0.005 mol) of oxalic acid dihydrate, and 260 g of methyl isobutyl ketone were charged, and the mixture was immersed in an oil bath and refluxed for 4 hours to carry out a polycondensation reaction. Thereafter, the temperature of the oil bath was raised over 3 hours, and then the pressure in the flask was reduced to 40 to 67 hPa, the volatiles were removed, and the dissolved resin was cooled to room temperature to obtain a polymer solid of Resin (B-1).

Synthesis Example 14 Synthesis of Resin (B-2) A polymer solid of Resin (B-2) was obtained by the same synthesis as in Synthesis Example 13, except that the amounts of m-cresol, p-cresol, and 2,5-dimethylphenol in Synthesis Example 13 were changed to 64.88 g (0.6 mol) of m-cresol, 32.44 g (0.3 mol) of p-cresol, and 12.22 g (0.1 mol) of 2,5-dimethylphenol, respectively.

Synthesis Example 15 Synthesis of Resin (B-3) A polymer solid of Resin (B-3) was obtained in the same manner as in Synthesis Example 13, except that the amounts of m-cresol, p-cresol, and 2,5-dimethylphenol in Synthesis Example 13 were changed to 32.44 g (0.3 mol) of m-cresol and 75.70 g (0.7 mol) of p-cresol, respectively.

[Synthesis Example 16] Synthesis of Resin (B-4) 2400 g of tetrahydrofuran, a mixed solution containing 2.56 g (0.04 mol) of sec-butyllithium as an initiator, was added with 95.18 g (0.54 mol) of p-t-butoxystyrene and 6.25 g (0.06 mol) of styrene, and the mixture was stirred for 3 hours. After polymerization, 12.82 g (0.4 mol) of methanol was added to terminate the polymerization. The reaction mixture was then poured into 3 L of methanol to purify the polymer, the precipitated polymer was dried, and further dissolved in 1.6 L of acetone. 2 g of concentrated hydrochloric acid was added at 60 ° C. and stirred for 7 hours. The polymer was then precipitated by pouring into water. The p-t-butoxystyrene was deprotected and converted to hydroxystyrene, and the mixture was washed three times with water. After drying for 24 hours in a vacuum dryer at 50 ° C., resin (B-4) was obtained.

Synthesis Example 17 Synthesis of Quinone Diazide Compound 1 Under a dry nitrogen stream, 42.45 g (0.1 mol) of TrisP-PA (trade name, manufactured by Honshu Chemical Industry Co., Ltd.) and 75.23 g (0.28 mol) of 5-naphthoquinone diazide sulfonyl chloride (NAC-5, manufactured by Toyo Gosei Co., Ltd.) were dissolved in 1,000 g of 1,4-dioxane. While the reaction vessel was ice-cooled, a mixture of 150 g of 1,4-dioxane and 30.36 g (0.3 mol) of triethylamine was added dropwise so that the temperature in the system did not exceed 35°C. After the dropwise addition, the mixture was stirred at 30°C for 2 hours. The triethylamine salt was filtered, and the filtrate was poured into 7 L of pure water to obtain a precipitate. This precipitate was collected by filtration and further washed with 2 L of 1% by mass hydrochloric acid. Thereafter, it was further washed twice with 5 L of pure water. This precipitate was dried in a vacuum dryer at 50° C. for 24 hours to obtain a quinone diazide compound 1 represented by the following formula in which an average of 2.8 of Q had been converted to 5-naphthoquinone diazide sulfonate.

In formula (3), ^Q1 , ^Q2 , and ^Q3 are hydrogen atoms or a structure represented by formula (4). From the ¹ H NMR spectrum, of 100 mol % of the total amount of the quinone diazide compound, the molar ratio a(0) of ^Q1 , ^Q2 , and ^Q3 all being hydrogen atoms was 0%, the molar ratio a(1) of Q1, ^Q2 , and ^Q3 one being a structure represented by formula (4) was 0 ^% , the molar ratio a( ² ) of Q1, ^Q2 , and ^Q3 two being a structure represented by formula ( ⁴ ) was 15%, and the molar ratio a( ³ ) of Q1, Q2, and ^Q3 all being a structure represented by formula (4) was 85%.

Synthesis Example 18 Synthesis of quinone diazide compound 2 [0134] A quinone diazide compound 2 represented by formula (3) in which an average of 2.6 Q's had been converted to 5-naphthoquinone diazide sulfonate was obtained in the same manner as in Synthesis Example 17, except that 69.86 g (0.26 mol) of 5-naphthoquinone diazide sulfonyl chloride was used.

From the ¹ H NMR spectrum, of 100 mol % of the total amount of the quinone diazide compound, the molar ratio a(0) of Q1, ^{Q2 ,} and ^Q3 all being hydrogen atoms was 0%, the molar ratio a( ¹ ) of Q1, ^Q2 , and ^Q3 one of which had a structure represented by formula (4) was 5%, the molar ratio a(2) of Q1, ^{Q2 ,} and ^Q3 two of which had a structure represented by formula (4) was 29%, and the molar ratio a( ³ ) of Q1, ^Q2 , and ^Q3 all of which had a structure represented by formula (4) was 66%.

The alkali dissolution rates and weight-average molecular weights determined using the above methods for the alkali-soluble resins (A-1 to A-11, B-1 to B-4) obtained in Synthesis Examples 2 to 16 are shown in Table 1. For A-1 to A-11, the esterification rates and the SP values of the monoamines used as end-capping agents are also shown in Table 1.

[Examples 1 to 31, Comparative Examples 1 to 6]
Resin (A), resin (B), and compound (C) were blended as shown in Table 2, and 1.4 g of quinone diazide compound 1 or quinone diazide compound 2 obtained in Synthesis Example 17 or 18, 1.1 g of Nikalac MX-270 (trade name, manufactured by Sanwa Chemical Co., Ltd.), and 17.1 g of GBL were added and stirred to obtain varnishes 1 to 37. The blending amounts and blending ratios of resin (A) and resin (B), the alkali dissolution rate ratio (R(B)/R(A)), and the weight average molecular weight ratio (Mw(A)/Mw(B)) are shown in Table 2, and the results of the evaluations (5) to (12) above are shown in Table 3.

The abbreviations for the materials used are as follows:
MPA: 3-methoxy-N,N-dimethylpropanamide DMPA: N,N-dimethylpropanamide TMU: N,N,N',N'-tetramethylurea DMI: 1,3-dimethyl-2-imidazolidinone

Claims (15)

A photosensitive resin composition containing at least a resin selected from the group consisting of polyimide, polybenzoxazole, polyamide, and precursors thereof and copolymers thereof (hereinafter, such a resin may be referred to as "resin (A)"), a resin selected from the group consisting of a phenolic resin and polyhydroxystyrene (hereinafter, such a resin may be referred to as "resin (B)"), and a photosensitizer,
The photosensitive resin composition is coated on a substrate and heat-treated to obtain a resin film that exhibits a phase-separated structure. The photosensitive resin composition according to claim 1, wherein the surface roughness of a resin film obtained by applying the photosensitive resin composition to a substrate and heating it at 120°C for 3 minutes is Ra(1), and the surface roughness of the film obtained after treating the resin film with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide at 23°C for 1 minute is Ra(2), and the difference between these (Ra(2) - Ra(1)) is 10 nm or more and 200 nm or less. Further, the composition contains a compound represented by any one of formulas (5) to (10) (hereinafter, sometimes referred to as “compound (C)”),
3. The photosensitive resin composition according to claim 1, wherein the content of the compound (C) is 0.1 to 1 mass% when the total mass of the photosensitive resin composition is 100 mass%.
( ^R3 represents a hydrogen atom, a hydroxyl group, or a monovalent organic group having 1 to 10 carbon atoms; ^R4 and ^R5 each independently represent a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms; ^R6 , ^R7 , ^R9 , ^R10 , and ^R13 to ^R20 each independently represent a monovalent organic group having 1 to 4 carbon atoms; ^R8 represents a monovalent organic group having 1 to 6 carbon atoms; and ^R11 and ^R12 each independently represent a monovalent organic group having 1 to 10 carbon atoms; and m is 1 or 2.) The photosensitive resin composition according to claim 1 or 2, wherein the static contact angle of water on the surface of a resin film obtained by applying the photosensitive resin composition to a substrate and heating it at 120°C for 3 minutes is θ(1), and the static contact angle of water on the surface of the film after treating the resin film with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide at 23°C for 1 minute is θ(2), and the difference between these (θ(1) - θ(2)) is 5° or more and less than 30°. When the weight average molecular weight of resin (A) is Mw(A) and the weight average molecular weight of resin (B) is Mw(B),
Mw(A) is 10,000 to 40,000;
3. The photosensitive resin composition according to claim 1, wherein Mw(A)/Mw(B) is 1 to 20. 3. The photosensitive resin composition according to claim 1, wherein all or a part of the carboxyl group terminals of the resin (A) have a structure represented by formula (1) or formula (2), and the solubility parameter (SP value) of an amine that reacts with the carboxyl group terminals to give the structure represented by formula (1) or formula (2) is 8.0 to 16.0.
In formula (1), R ¹ represents a monovalent organic group having 1 to 20 carbon atoms, and * represents a bonding point with a dicarboxylic acid residue, a tricarboxylic acid residue, or a tetracarboxylic acid residue.
In formula (2), ^R2 represents a monovalent organic group having 1 to 20 carbon atoms, and * represents the point of attachment to a dicarboxylic acid residue, a tricarboxylic acid residue, or a tetracarboxylic acid residue. When the dissolution rate of resin (A) in a 2.38 mass% aqueous solution of tetramethylammonium hydroxide at 23°C is R(A) (nm/min), and the dissolution rate of resin (B) in a 2.38 mass% aqueous solution of tetramethylammonium hydroxide at 23°C is R(B) (nm/min),
R(A) is 500 to 5000 nm/min;
3. The photosensitive resin composition according to claim 1, wherein R(B)/R(A) is 2.5 to 30. The photosensitive resin composition according to claim 1 or 2, wherein resin (A) has carboxyl groups and esterified carboxyl groups in its molecular structure, and the proportion of esterified carboxyl groups is 50 to 80 mol % when the total amount of carboxyl groups and esterified carboxyl groups is 100 mol %. The photosensitive resin composition according to claim 5, wherein the Mw(A)/Mw(B) ratio is 7 to 10. 3. The photosensitive resin composition according to claim 1, wherein the phase-separated structure of a resin film obtained by applying the photosensitive resin composition to a substrate and heat-treating the composition is such that, when an image of a cross section of the resin film is analyzed under the following conditions, one phase occupies 30 to 50% of the area of the entire image.
<Image analysis conditions>
The cross section of the resin film after heat treatment is observed using a transmission electron microscope, and a 2 μm square area is cut out from the obtained image. The image is converted to 16 bits using the image analysis software "ImageJ", and then smoothed. At this time, a Gaussian filter σ = 2.0 is used. Next, the image background is subtracted. At this time, the rolling ball radius is set to 30 pixels. Next, the contrast of the image is enhanced. At this time, the number of saturated pixels is set to 0.35%. Next, the image is binarized by setting a threshold value using IsoData Auto, and the area ratio of the colored area to the entire image is calculated. A cured film obtained by curing the photosensitive resin composition described in claim 1 or 2. The cured film according to claim 11, wherein the surface roughness of the cured film is Ra(3) and the surface roughness of a film obtained by treating the cured film with oxygen plasma is Ra(4), and the difference between the surface roughnesses (Ra(4) - Ra(3)) is 10 nm or more and 200 nm or less. The cured film according to claim 11, wherein when an image of a cross section of the cured film is analyzed under the following conditions, one phase occupies 30 to 50% of the area of the entire image.
<Image analysis conditions>
The cross section of the cured film is observed using a transmission electron microscope, and a 2 μm square area is cut out from the obtained image. The image is converted to 16-bit using the image analysis software "ImageJ," and then smoothed. At this time, a Gaussian filter σ = 2.0 is used. Next, the image background is subtracted. At this time, the rolling ball radius is set to 30 pixels. Next, the contrast of the image is enhanced. At this time, the number of saturated pixels is set to 0.35%. Next, the image is binarized by setting a threshold value using IsoData Auto, and the area ratio of the colored area to the entire image is calculated. An interlayer insulating film using the cured film described in claim 11. A semiconductor protective film using the cured film described in claim 11.