JP5486381B2 - Positive photosensitive resin composition and method for producing relief pattern using the same - Google Patents

Description

  The present invention relates to a method for producing a relief pattern of polybenzoxazole useful as an electrical and electronic insulating material, particularly a surface protective film for semiconductor elements, an interlayer insulating film, and a buffer coat, and a positive photosensitive resin composition used therefor.

  A relief pattern is generally produced by dissolving a photosensitive resin composition in an organic solvent to form a film, and then pattern-exposing the film with actinic rays and developing it with a developer. As a resin constituting the relief pattern for electrical and electronic insulating materials, a polyimide resin having both excellent heat resistance, electrical characteristics, mechanical characteristics, and the like has been conventionally used. On the other hand, in recent years, with the progress of higher integration and larger size of semiconductor elements, there is a demand for thinner and smaller sealing resin packages. There are methods such as surface mounting by LOC (lead on chip) or solder reflow. As a result, a resin excellent in mechanical properties, heat resistance and the like has been required more than ever.

  In order to meet such requirements, it has been proposed to use a polybenzoxazole resin instead of a polyimide resin as a resin constituting the relief pattern. A polybenzoxazole resin is excellent in mechanical properties and heat resistance, but has a very low solubility in an organic solvent, so that it is difficult to form into a film as it is. Therefore, a relief pattern using a polybenzoxazole resin is prepared by dissolving a polybenzoxazole resin precursor (polyamide) in an organic solvent, forming it into a film shape, pattern exposure and development, and then heating the ring to close the precursor. Is converted to polybenzoxazole resin. However, even in the method via this precursor, the solubility of the precursor cannot be said to be sufficiently high, and further improvement is required.

  As a method for improving the solubility of the precursor, it has been proposed to introduce a methylene group having a bulky group such as a trifluoromethyl group into the molecular chain (see Patent Document 1). Although this method improves the solubility of the precursor to some extent, since the methylene group in the precursor remains in the final polybenzoxazole resin, the heat resistance and mechanical properties, which are the advantages of the polybenzoxazole resin, are improved. There was a problem that the height was lost. Further, this precursor cannot be said to have sufficient i-line (365 nm) and g-line (436 nm) transmittance due to its structure, and the film sensitivity at the time of forming the relief pattern was not sufficient.

JP 2000-143805 A

  The present invention was devised in view of the current state of the prior art, and its purpose is to improve the heat resistance and mechanical properties of the final polybenzoxazole resin while having high solubility and i-line and g-line transmittance. An object of the present invention is to provide a method for producing a relief pattern using a polybenzoxazole precursor which is not damaged, and a positive photosensitive resin composition for use in such a production method.

  In order to achieve such an object, the present inventors have intensively studied the types of substituents to be introduced into the precursor polyamide of the polybenzoxazole resin and the introduction positions thereof. As a result, the hydroxy group of the polyamide was converted to a tert-butoxycarbonyl group ( (Hereinafter, also referred to as a t-Boc group), the solubility of the polyamide in an organic solvent and the i-line and g-line transmittance can be increased. It was found that it was released from the resin and was not present in the final polybenzoxazole, and as a result, the original heat resistance and high mechanical properties of polybenzoxazole were not impaired, and the present invention was completed.

（式中、Ｒ_１はｔｅｒｔ−ブトキシカルボニル基を表すが、ｎ個の繰返し単位中の一部は、Ｒ_１が水素原子であっても良く、ｎは５０以上の整数を表す。）；
（ｉｉ）（ｉ）で調製された溶液をキャストしてポリアミドフィルムを得る工程；
（ｉｉｉ）（ｉｉ）で得られたポリアミドフィルムを活性光線でパターン露光する工程；
（ｉｖ）（ｉｉｉ）で露光されたポリアミドフィルムをアルカリ溶液で現像して露光部分を除去する工程；及び
（ｖ）（ｉｖ）で露光部分を除去されたポリアミドフィルムを加熱してフィルム中のポリアミドをポリベンズオキサゾールに変換する工程
を含むことを特徴とするレリーフパターンの製造方法。
（２） 一般式［Ｉ］で表されるポリアミドと光酸発生剤を含有することを特徴とするポジ型感光性樹脂組成物。 That is, according to the present invention, the following configurations (1) and (2) are provided.
{1} (i) A step of preparing a solution by dissolving a polyamide represented by the following general formula [I] in an organic solvent together with a photoacid generator

(Wherein, it represents a R ₁ is tert- butoxycarbonyl group, a portion in the n repeating units, may be R ₁ is hydrogen atom, n is an integer of more than 50.);
(Ii) a step of casting the solution prepared in (i) to obtain a polyamide film;
(Iii) pattern exposure of the polyamide film obtained in (ii) with actinic rays;
(Iv) a step of developing the polyamide film exposed in (iii) with an alkaline solution to remove the exposed portion; and (v) heating the polyamide film from which the exposed portion has been removed in (iv) to form a polyamide in the film. The manufacturing method of the relief pattern characterized by including the process of converting into polybenzoxazole.
(2) A positive photosensitive resin composition comprising a polyamide represented by the general formula [I] and a photoacid generator.

  The method for producing a relief pattern of the present invention uses a polyamide in which at least a part of the hydroxy group is substituted with a t-Boc group as a precursor, so that the solubility in an organic solvent is high and film formation is easy. Moreover, since the polyamide substituted by t-Boc group has high i line | wire and g line | wire transmittance, the film sensitivity at the time of relief pattern formation is also high. Furthermore, since the t-Boc group present in the precursor polyamide does not remain in the final polybenzoxazole film, the obtained relief pattern exhibits the excellent heat resistance and mechanical properties inherent to polybenzoxazole.

FIG. 1 shows UV-VIS absorption spectra of t-Boc substituted polyamide and unsubstituted polyamide. FIG. 2 shows the results of differential thermal analysis of t-Boc substituted polyamide and unsubstituted polyamide in a nitrogen stream.

  The present invention is characterized in that a specific substituted polyamide is used as a precursor polyamide in a method for producing a relief pattern from a polybenzoxazole resin via a precursor polyamide.

First, the substituted polyamide used in the present invention will be described. The substituted polyamide used in the present invention is represented by the following general formula [I].

In the general formula [I], R ₁ represents a tert-butoxycarbonyl group (t-Boc group), and R ₁ may be a hydrogen atom in a part of the n repeating units. Polyamide usually has a hydroxy group in the ortho position relative to the amide group and is poor in solubility in an organic solvent. However, in the substituted polyamide of the present invention, at least a part of the hydroxy group is substituted with a t-Boc group. Therefore, it has excellent solubility in organic solvents.

  The substituted polyamide used in the present invention includes not only those in which all of the hydroxy groups in n repeating units are substituted with t-Boc groups, but also those in which at least a part remains unsubstituted. This is because some hydroxy groups may remain unsubstituted depending on the conditions for the substitution reaction of the hydroxy group to the t-Boc group. Specifically, the substitution ratio of the hydroxy group with the t-Boc group is preferably 50% or more, more preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. When the substitution ratio is less than the lower limit, the solubility of the obtained substituted polyamide in an organic solvent may be lowered.

  Further, the repeating number n of the polyamide represented by the general formula [I] is an integer of 50 or more, preferably 100 or more, more preferably 200 or more. If the number of repetitions n is less than the lower limit, the polyamide film obtained by molding and the polybenzoxazole film obtained by subsequent heat ring closure may become brittle. The upper limit of the number of repetitions n is not particularly limited, but is generally about 2000 from the viewpoint that if the viscosity of the polyamide solution is too high, the fluidity becomes low and it becomes difficult to form a film.

R ₁ in the general formula [I] corresponds to a protecting group. In the present invention, it is important that this protecting group is a t-Boc group. For protecting groups other than the t-Boc group, for example, methyl group, ethyl group, phenyl group, benzyl group, etc., when these groups are substituted with the hydroxyl group of polyamide, under basic conditions in which sodium hydroxide exists. In this case, since the solubility of the polyamide is low and hydrolysis at the amide group site occurs, it is not easy to perform the substitution reaction. Even if the substitution can be made, the reaction of the deprotecting group must be carried out in the presence of palladium carbon or a strong acid. It is not suitable for the method of the present invention for carrying out the ring closure reaction to oxazole. Furthermore, when substituted with a phenyl group or the like, the ultraviolet absorption wavelength of the polyamide shifts to the longer wavelength side, so that the i-line and g-line transmittance of the polyamide decreases, and the film sensitivity at the time of relief pattern formation is insufficient. Become. On the other hand, if the protecting group is a t-Boc group, the substitution of the polyamide to the hydroxyl group is easy, the i-line and g-line permeability is excellent, and the t-Boc group is relatively relatively present during the ring-closing reaction from polyamide to polybenzoxazole. Since it comes off easily, the ring closure reaction proceeds sufficiently.

The polyamide represented by the general formula [I] can be produced, for example, by a production method including the following steps.
(A) reacting silylated 4,6-diaminoresorcinol with terephthalic acid chloride to synthesize a polyamide having a hydroxy group in the ortho position relative to the amide group; and (b) at least one of the synthesized polyamides. A step of substituting part of the hydroxy group with a tert-butoxycarbonyl group to obtain a substituted polyamide.

Silylated 4,6-diaminoresorcinol used in step (a) can be obtained, for example, by reacting commercially available 4,6-diaminoresorcinol dihydrochloride with a silylating agent in an organic solvent. (See Equation 1 below). After completion of the reaction of Formula 1, vacuum distillation is performed to isolate the desired silylated product.

  As the silylating agent in the reaction of Formula 1, a general silylating agent can be used. Specifically, hexamethyldisilazane, chlorotrimethylsilane, or a mixture thereof can be used. As the organic solvent, aromatic solvents such as benzene, toluene, xylene and anisole, and those obtained by dehydration treatment of tetrahydrofuran, carbon tetrachloride and the like can be used. The reaction temperature is usually 80 to 130 ° C. The reaction time is usually 1 hour to 100 hours. If the reaction time is less than 1 hour, the amount of unreacted substances may increase. If the reaction time is longer than 100 hours, the product may be decomposed and the yield may be reduced.

The terephthalic acid chloride used in the step (a) can be obtained, for example, by reacting terephthalic acid with thionyl chloride (see Formula 2 below).

  Moreover, a commercial item may be used for the terephthalic acid chloride of a process (a). In either case, in order to obtain a polyamide with a high degree of polymerization, it is desirable to purify by recrystallization from an organic solvent. As this organic solvent, hexane, cyclohexane, cyclohexanone, or the like can be used.

In step (a), the silylated 4,6-diaminoresorcinol prepared as described above and terephthalic acid chloride are reacted to synthesize a polyamide having a hydroxy group in the ortho position relative to the amide group (the following formula 3). Specifically, this step can be performed by preparing an exact equimolar amount of silylated 4,6-diaminoresorcinol and terephthalic acid chloride and reacting them in an organic solvent at a low temperature.

  As an organic solvent in the reaction of Formula 3, dimethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, pyridine, tetrahydrofuran, 1,4-dioxane, carbon tetrachloride, chloroform, tetrachloroethane and the like are dehydrated. Can be used. Although reaction temperature changes with kinds of organic solvent to be used, it is -10-60 degreeC normally, Preferably it is -10-20 degreeC. The reaction time is usually 1 hour to 24 hours, preferably 1 hour to 12 hours.

  After completion of the reaction of Formula 3, if desired, the reaction solution is dropped into a large amount of alcohol to precipitate polyamide, which is filtered off as a solid and washed with alcohol. As this alcohol, methanol, ethanol, propanol, butanol and the like can be used.

Since the silyl group is eliminated during the reaction in the step (a) or during the post-reaction treatment, the polyamide synthesized in the step (a) has a considerably low solubility in an organic solvent. Therefore, it is very difficult to dissolve this in an organic solvent to form a cast film, and the strength of the resulting film is extremely low. Therefore, in order to increase the solubility in a general organic solvent, in step (b), at least some of the hydroxy groups in the polyamide synthesized in step (a) are tert-butoxycarbonyl groups (also referred to as t-Boc groups). To obtain a substituted polyamide (see Formula 4 below). Specifically, this step can be performed by reacting the polyamide synthesized in step (a) with di-tert-butyl dicarbonate in an organic solvent in the presence of a basic substance.

  As an organic solvent in the reaction of Formula 4, dimethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, pyridine, tetrahydrofuran, 1,4-dioxane, toluene, benzene, pyridine, anisole, etc. should be used. Can do. As the basic substance, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, triethylamine, trimethylamine, ammonia and the like can be used. The reaction temperature is usually 0-50 ° C, preferably 0-35 ° C. The reaction time is usually 0.5 hours to 50 hours, preferably 0.5 hours to 30 hours.

  After completion of the reaction of Formula 4, if desired, the reaction solution is dropped into water or alcohol to precipitate the substituted polyamide, which is filtered as a solid and washed well with water or alcohol to purify the substituted polyamide. As this alcohol, methanol, ethanol, propanol, butanol and the like can be used.

Next, the manufacturing method of the relief pattern of this invention is demonstrated. The method for producing a relief pattern according to the present invention includes the following steps:
(I) a step of preparing a solution by dissolving the polyamide represented by the general formula [I] in an organic solvent together with a photoacid generator;
(Ii) a step of casting the solution prepared in (i) to obtain a polyamide film;
(Iii) pattern exposure of the polyamide film obtained in (ii) with actinic rays;
(Iv) a step of developing the polyamide film exposed in (iii) with an alkaline solution to remove the exposed portion; and (v) heating the polyamide film from which the exposed portion has been removed in (iv) to form a polyamide in the film. The step of converting to polybenzoxazole.

  The photoacid generator used in step (i) is a compound that generates an acid upon irradiation with actinic rays. As the photoacid generator, a compound that generates Bronsted acid by light irradiation is used. These are roughly classified into various onium salts and sulfonic acid esters, and examples thereof include diazonaphthoquinone, aryldiazonium salts, diaryliodonium salts, and triarylsulfonium salts. Specifically, 1,2-naphthoquinone-2-diazide-5-sulfonic acid, 1,2-naphthoquinone-2-diazide-4-sulfonic acid, low molecular weight hydroxybenzene, 2- and 4-methyl-phenol Ester of 4,4′-hydroxy-propane, phenol compound and 1,2-naphthoquinone-2-diazido-5-sulfonic acid or 1,2-naphthoquinone-2-diazido-4-sulfonic acid, ( 4-phenylthiophenyl) diphenylsulfonium triflate, triphenylsulfonium triflate, N-hydroxy-5-norbornene-2,3-dicarboximidoperfluoro-1-butanesulfonate, diphenylindonium-9 , 10-dimethoxyanthracene-2-sulfonate and the like. These may be used alone or in combination of two or more. The usage-amount of a photo-acid generator is 0.1 to 10 weight% normally with respect to the polyamide of general formula [I], Preferably it is 0.1 to 5 weight%.

  Examples of the organic solvent used in the step (i) include general-purpose organic solvents such as dimethylformamide, N-methyl-2-pyrrolidone, and N, N-dimethylacetamide. The concentration of the polyamide of the general formula [I] in the solution is not particularly limited as long as it is a concentration suitable for casting, and is usually 1 mg / ml to 50 mg / ml, preferably 1 mg / ml to 30 mg / ml. is there.

  Next, in step (ii), the solution prepared in step (i) is cast to obtain a polyamide film. This step can be performed by any conventionally known method. For example, the solution is cast on a substrate made of a material such as glass, fluororesin, aluminum, iron, or stainless steel, a sheet, a film, or the like, and is subjected to normal pressure. Alternatively, a method of removing the organic solvent by heating under reduced pressure, or a method of extruding the solution from a die and taking it up on a roll or an endless belt can be employed.

Next, in the step (iii), the polyamide film obtained in the step (ii) is irradiated with actinic rays through a photomask having a predetermined pattern, and pattern exposure is performed. When actinic rays are irradiated, an acid is generated from the photoacid generator in the irradiated film. This acid reacts with the t-Boc group of the polyamide of the general formula [I] in the film of the irradiated part to remove the t-Boc group from the polyamide, changing the polyamide from alkali-insoluble to alkali-soluble. Thereby, a difference in alkali solubility occurs between the irradiated portion and the non-irradiated portion. Moreover, since the polyamide of the general formula [I] has a t-Boc group, the peak of the light absorption spectrum is shifted to the short wavelength side as compared with the polyamide having no t-Boc group. The transmittance at i-line (365 nm) and g-line (436 nm), which are general absorption peaks, is high. Therefore, the irradiated actinic rays are hardly absorbed by the polyamide in the film, but are exclusively absorbed by the photoacid generator. As a result, the film sensitivity at the time of forming the relief pattern is increased. As the actinic ray, ultraviolet light having a wavelength of usually 250 to 450 nm is used. The irradiation time of actinic rays is usually 0.01 to 60 minutes, preferably 0.01 to 10 minutes. Further, the exposure amount necessary for obtaining a pattern with a high resolution of 10 μm or less is 600 mJ / cm ² or less.

  Next, in step (iv), the exposed polyamide film is developed with an alkaline solution to remove the exposed portion (alkali-soluble portion). Examples of the alkaline compound used in the alkaline solution include alkali metals, alkaline earth metals or ammonia, and amine compounds. Specifically, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, aqueous ammonia, tertiary amines such as ethylamine, n-propylamines, triethylamine, methyldiethylamine, Alcohol amines such as diethanolamine and triethanolamine, and quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide can be used. As a solvent for dissolving these alkaline compounds, water, alcohols such as methanol and ethanol, and ethers such as tetrahydrofuran and dioxane can be used. In many electronic devices, residual metal may adversely affect the electrical characteristics, and therefore a tetramethylammonium hydroxide aqueous solution that does not contain metal is preferably used as the alkaline solution. If desired, an appropriate amount of a surfactant may be added to the alkaline solution. The concentration of the alkaline compound in the alkaline solution is usually 0.05 to 10% by weight, preferably 0.1 to 5% by weight.

  As a developing method, a method in which an alkaline solution is applied to the film by a method such as spraying, showering, dipping, or ultrasonic waves can be employed. Development conditions are not particularly limited, but are usually about 10 seconds to 10 minutes at room temperature.

  After development, the process may proceed to the next step (v) as it is, but in order to obtain a clear positive pattern, it is preferable to wash with pure water. Further, after the development, it is desirable to stabilize the pattern by drying at 100 ° C. or lower under normal pressure or reduced pressure.

Next, the polyamide film thus obtained is heated in step (v) to cyclize the polyamide in the film and convert it into polybenzoxazole (see Formula 5 below).

  In the step (v), the temperature of the heat treatment is not particularly limited, but is usually 170 to 400 ° C, preferably 200 to 400 ° C. If the heat treatment temperature is higher than the upper limit, side reactions may occur and mechanical characteristics and the like may be reduced. Moreover, when heat processing temperature is lower than the said lower limit, ring closure reaction will become very slow and there exists a possibility that the target polybenzoxazole film may not be obtained. The time for the heat treatment is usually 1 minute to 180 minutes, preferably 10 minutes to 150 minutes. Note that the heat treatment is preferably performed in an inert gas atmosphere because there is little decrease in mechanical properties due to side reactions.

  In the relief pattern obtained as described above, the t-Boc group present in the raw material polyamide is liberated from the resin during the heat ring closure of the polyamide to polybenzoxazole, and finally the relief pattern is formed. It does not remain in polybenzoxazole. For this reason, the relief pattern of the present invention can exhibit the excellent heat resistance and mechanical properties inherent to polybenzoxazole.

  The polyamide of the general formula [I] obtained as described above constitutes the positive photosensitive resin composition of the present invention together with a photoacid generator. In the positive photosensitive resin composition of the present invention, the acid generated from the photoacid generator upon irradiation with actinic rays releases the t-Boc group of the polyamide of the general formula [I], so that the irradiated portion is alkali-insoluble. It is used to change from alkaline to soluble. The positive photosensitive resin composition of the present invention can be produced by uniformly mixing the polyamide of the general formula [I] and a photoacid generator by an appropriate means. The blending ratio of both components in the composition is not particularly limited, but usually the photoacid generator is 0.1 to 10% by weight, preferably 0.1 to 5% with respect to the polyamide of the general formula [I]. % By weight.

  Examples The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. In addition, each characteristic in an Example was measured with the following method.

1. Light transmittance Using a UV-visible spectrophotometer (UV-2450) manufactured by Nippon SHIMADZU, the visible / ultraviolet light transmittance of a polyamide film (film thickness: about 10 μm) was measured in the range of 300 nm to 800 nm, and i-line (365 nm) and The light transmittance (%) at g-line (436 nm) was determined.

2. Evaluation of Sensitivity The minimum exposure amount required to clearly form a pattern with a resolution of 10 μm was defined as sensitivity. Whether or not a pattern having a resolution of 10 μm was clearly formed was determined by observing a relief pattern after exposure and development with a microscope. The exposure amount was measured using an ultraviolet illuminance meter / light quantity system (UV-M03: manufactured by Oak Co., Ltd.).

3. Calculation of remaining film ratio The film thickness of the non-exposed part of the film before and after development was measured, and the remaining film ratio was calculated by the following calculation method.
Residual film ratio (%) = {(film thickness after development) / (film thickness before development)} × 100

4). Appearance Evaluation of Film The appearance of the film after development and after heating was observed visually and with a microscope. With respect to the appearance evaluation after development, it was evaluated as “good” if there was no undeveloped undeveloped residue and the pattern edge was smooth. In addition, regarding the appearance evaluation after heating, it was evaluated as “good” if there was no cracking or swelling of the film, voids, peeling, or cracking or warping of the wafer.

[Reference example]
1. Production of N, N ′, O, O′-tetra (trimethylsilyl) -4,6-diaminoresorcinol After the system was placed in a dry nitrogen atmosphere, 4,6-diaminoresorcinol dihydrochloride 20 was placed in a 300 ml two-necked flask. 0.0 g (94.0 mmol), dehydrated toluene 100 ml, hexamethyldisilazane 100 ml (370 mmol), and chlorotrimethylsilane 15 ml (120 mmol) were added and reacted at 100 ° C. for 72 hours. After completion of the reaction, toluene, excess hexamethyldisilazane and chlorotrimethylsilane were removed under reduced pressure, and the residue was purified by distillation under reduced pressure. The boiling point of the product was 146-149 ° C./0.9 mmHg, and the yield was 43.7 g (87%).

2. 3. Preparation of tert-butoxycarbonyl-substituted polyamide (i) N, N ′, O, O′-tetra (trimethylsilyl) -4,6-diaminoresorcinol prepared in 1 above in a 300 ml three-necked flask under a dry nitrogen atmosphere 29 g (10 mmol) and 20 ml of dehydrated N-methyl-2-pyrrolidone were added and dissolved at 0 ° C. Purified commercially available terephthalic acid chloride (2.03 g, 10 mmol) was added little by little and reacted at 0 ° C. for 6 hours.

(Ii) Next, 50 ml of N-methyl-2-pyrrolidone was added to the reaction solution, and the mixture was further stirred for 1 hour. To this reaction solution, 8.3 ml (60 mmol) of triethylamine and 9.2 ml (40 mmol) of di-tert-butyl dicarbonate were added, and the mixture was further reacted for 24 hours. After completion of the reaction, the reaction solution was dropped into 1000 ml of methanol, and the precipitate was collected by filtration and washed with 100 ml of methanol to obtain a t-Boc substituted polyamide. The yield was 3.7 g (83%). The solubility of this t-Boc substituted polyamide in N-methylpyrrolidone was 5 mg / ml or more. Further, the UV-VIS absorption spectrum of the t-Boc substituted polyamide was compared with that of the unsubstituted polyamide. The result is shown in FIG. From FIG. 1, by substituting the hydroxyl group at the ortho position of the amide group with a t-Boc group, the maximum absorption at 344 nm is shifted to 290 nm, and the t-Boc-substituted polyamide is converted to i-line (365 nm) and g-line (436 nm). ) Shows a high light transmittance. The results of differential thermal analysis of this t-Boc substituted polyamide in a nitrogen stream are shown in FIG. 2 in comparison with the unsubstituted polyamide.

[Example 1]
Production of relief pattern (i) 0.2 g of t-Boc substituted polyamide produced in Reference Example and 0.02 g of (4-phenylthiophenyl) diphenylsulfonium triflate as a photoacid generator were mixed with N-methyl-2-pyrrolidone. A casting solution was prepared by dissolving in 2.74 g. Next, this solution was dropped on a 1 cm × 1 cm glass plate, and the solvent was distilled off in an environment of 3 mmHg at room temperature for 24 hours and then at 100 ° C., 200 ° C., and 300 ° C. for 1 hour in an environment of 3 mmHg. A polyamide film having a thickness of 10 μm was obtained. The light transmittances of the obtained polyamide film at i-line and g-line were 88% and 93%, respectively.

(Ii) Next, the film was irradiated with ultraviolet rays using a super high pressure mercury lamp through a photomask having a pattern with a resolution of 10 μm. Thereafter, development was performed using a 2.38 wt% tetramethylammonium hydroxide aqueous solution. It was then washed with distilled water and dried. The sensitivity of the film was 300 mJ / cm ² and the remaining film rate was 92%. The appearance of the film after development was also good.

(Iii) Next, this polyamide film was heated together with a glass plate at 360 ° C. for 30 minutes under a nitrogen stream to convert the polyamide into polybenzoxazole, thereby obtaining a relief pattern of polybenzoxazole. The decomposition temperature of this polybenzoxazole was about 650 ° C. Moreover, the external appearance of the film after a heating was favorable.

[Example 2]
A relief pattern of polybenzoxazole was obtained in the same manner as in Example 1 except that diphenylindonium-9,10-dimethoxyanthracene-2-sulfonate was used as the photoacid generator. The film light transmittance, sensitivity, remaining film rate, and appearance evaluation after development and after heating were at the same level as in Example 1.

[Comparative example]
An attempt was made to produce a relief pattern in the same manner as in Example 1 using an unsubstituted polyamide instead of the t-Boc substituted polyamide. The solubility of this unsubstituted polyamide in N-methylpyrrolidone was about 0.2 mg / ml. A casting solution was prepared at this polymer concentration, and then filtered through a membrane filter and cast to obtain a polyamide film. When the i-line and g-line transmittances of this film were measured, they were extremely low, 65% and 79%, respectively, so the subsequent steps were not performed.

  In the method for producing a relief pattern of the present invention, since a polyamide in which at least a part of hydroxy groups is substituted with a t-Boc group is used as a precursor, film formation is easy. Moreover, since the polyamide substituted by the t-Boc group has high i-line and g-line transmittance, the film sensitivity at the time of relief pattern formation is also high. Furthermore, since the t-Boc group present in the precursor polyamide does not remain in the final polybenzoxazole film, the obtained relief pattern exhibits the excellent heat resistance and mechanical properties inherent to polybenzoxazole. Therefore, the method for producing a relief pattern of the present invention is extremely useful for producing a relief pattern of polybenzoxazole, which is useful as a surface protection film, an interlayer insulation film, and a buffer coat for electrical and electronic insulating materials, particularly semiconductor elements. .

Claims (2)

(I) A step of preparing a solution by dissolving a polyamide represented by the following general formula [I] in an organic solvent together with a photoacid generator

(Wherein, it represents a R ₁ is tert- butoxycarbonyl group, a portion in the n repeating units, may be R ₁ is hydrogen atom, n is an integer of more than 50.);
(Ii) a step of casting the solution prepared in (i) to obtain a polyamide film;
(Iii) pattern exposure of the polyamide film obtained in (ii) with actinic rays;
(Iv) a step of developing the polyamide film exposed in (iii) with an alkaline solution to remove the exposed portion; and (v) heating the polyamide film from which the exposed portion has been removed in (iv) to form a polyamide in the film. The manufacturing method of the relief pattern characterized by including the process of converting into polybenzoxazole.   A positive photosensitive resin composition comprising a polyamide represented by the general formula [I] and a photoacid generator.

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