JP3946673B2 - Photosensitive resin composition - Google Patents

Description

  The present invention relates to a positive photosensitive resin composition used as an electrical and electronic insulating material in the manufacture of semiconductor devices and the like. Specifically, this photosensitive resin composition provides insulation protection on semiconductor elements such as ICs and LSIs. The present invention is applied to a field where a film is formed and processing of a fine pattern is required.

  2. Description of the Related Art Conventionally, in ICs, LSIs, and the like, organic protective films such as polyimide resins and polybenzoxazole resins excellent in heat resistance, chemical resistance, electrical insulation, and the like are coated to protect semiconductor elements.

  Furthermore, using polyimide resin, polybenzoxazole resin, etc., that imparts a photosensitive function to these resins, parts that do not require protective films such as electrode parts and dicing lines are processed using actinic rays such as ultraviolet exposure. As a result, the process has been shortened, the process has been rationalized, and the amount of harmful substances used has been reduced.

  In recent years, the amount of organic solvent used has been reduced by changing the developing solution of the photosensitive resin from an organic solvent type to an alkaline aqueous solution type.

  Polyimide resins, polybenzoxazole resins, etc. that have been imparted with a photosensitive function have low solubility in solvents, so they are coated with resin precursors such as polyamide resins and polyhydroxyamides dissolved in solvents. Since the thermal ring closure reaction is performed to polyimide resin, polybenzoxazole resin, and the like after exposure and development processing, high-temperature heat treatment at 300 ° C. or higher is performed, and it is difficult to use for semiconductor elements that dislike high-temperature processing.

  Moreover, polyimide resin, polybenzoxazole resin, and the like are expensive and have a large cost burden.

  On the other hand, novolak resin-based resists used in circuit formation of semiconductor elements are removed after performing wet etching, dry etching, etc. on metal films and silicon-based films using a pattern processed using this resist as a mask. End up.

  Since these novolak resins are less expensive than polyimide resin resins, the introduction of a crosslinking agent or the like into the novolak resin resins to improve heat resistance and the use as a protective film for semiconductor elements has been studied. At a high temperature of 200 ° C. or higher, the resin is severely deteriorated and cannot be practically used.

  The object of the present invention is to eliminate the above-mentioned conventional drawbacks, and can be cured even at a low temperature of 300 ° C. or lower as compared with a conventional semiconductor element surface protective film, and can be processed by ultraviolet exposure, and becomes a wafer as a base material. The present invention provides a positive photosensitive resin composition having high adhesion to the resin and having a low resin cost.

  As a result of diligent research to achieve the above object, the present inventor has found that the above object can be achieved by a resin composition described later, and has completed the present invention.

（但し、式中、Ｘは水素原子または−ＣＨ₂ ＯＨで、ｍは１〜２の整数であり、Ｒは芳香族環が−ＣＨ₂ −、−ＣＨ₂ −Ｏ−ＣＨ₂ −若しくは−Ｏ−を介在して結合する有機基で、ｎは１以上の整数である）
を必須成分とすることを特徴とするポジ型感光性樹脂組成物であり、また、この（Ａ）成分のフェノール樹脂に（Ｂ）次の一般式で示されるナフトキノンジアジドスルホン酸クロリド

がフェノール性化合物にエステル化反応をした化合物および
（Ｃ）これらを溶解する溶剤とからなることを特徴とするポジ型感光性樹脂組成物である。 That is, the present invention
(A) A phenol resin having a methylol group represented by the following general formula

(Wherein, X is a hydrogen atom or —CH ₂ OH, m is an integer of 1 to 2, and R is an aromatic ring of —CH ₂ —, —CH ₂ —O—CH ₂ — or —O. An organic group bonded via-, and n is an integer of 1 or more)
Is a positive photosensitive resin composition characterized by comprising an essential component, and (B) a naphthoquinonediazide sulfonic acid chloride represented by the following general formula:

Is a positive photosensitive resin composition comprising a compound obtained by esterifying a phenolic compound and (C) a solvent for dissolving them.

  The resin composition of the present invention can be cured at a low temperature of 300 ° C. or lower by using a naphthoquinone diazide-based photosensitizer obtained by esterification of a phenol resin having a methylol group and naphthoquinone diazide sulfonic acid chloride. It is a positive photosensitive resin composition that enables processing of a positive pattern by development using an aqueous solution, has high adhesion to a wafer, and has a low resin cost.

（但し、式中、Ｘは水素原子または−ＣＨ₂ ＯＨで、ｍは１〜２の整数であり、Ｒは芳香族環が−ＣＨ₂ −、−ＣＨ₂ −Ｏ−ＣＨ₂ −若しくは−Ｏ−を介在して結合する有機基で、ｎは１以上の整数である）
具体的には、例えば次の構造式のものがあるが、それらに限定されるものではなく、またフェノール樹脂反応の副反応として−ＣＨ₂ −以外に生ずる種々の介在結合がある。

（但し、ｍは１〜２の整数、ｎ、ｎ′は１以上の整数である）

（但し、ｍは１〜２の整数、ｎ、ｎ′は１以上の整数である）
本発明に用いる（Ｂ）の感光剤としてナフトキノンジアジド化合物をフェノール性化合物とエステル化反応させた化合物は、ポジレジストの分野で用いられている公知の物質である。 The (A) phenol resin having a methylol group used in the present invention is represented by the following general formula.

(Wherein, X is a hydrogen atom or —CH ₂ OH, m is an integer of 1 to 2, and R is an aromatic ring of —CH ₂ —, —CH ₂ —O—CH ₂ — or —O. An organic group bonded via-, and n is an integer of 1 or more)
Specific examples include, but are not limited to, the following structural formulas, and there are various intervening bonds generated other than —CH ₂ — as a side reaction of the phenol resin reaction.

(Where m is an integer of 1 to 2, and n and n ′ are integers of 1 or more)

(Where m is an integer of 1 to 2, and n and n ′ are integers of 1 or more)
The compound obtained by esterifying a naphthoquinonediazide compound with a phenolic compound as the photosensitive agent (B) used in the present invention is a known substance used in the field of positive resists.

等が挙げられる。 In general, a naphthoquinone diazide photosensitizer is obtained by a condensation reaction between a diazonaphthoquinonesulfonic acid chloride and a compound having a phenolic hydroxyl group. As diazonaphthoquinonesulfonic acid chloride, 1,2-naphthoquinone-2-diazide-5-sulfonic acid chloride or 1,2-naphthoquinone-2-diazide-4-sulfonic acid chloride represented by the following formula:

Etc.

  Examples of the compound having a phenolic hydroxyl group that undergoes a condensation reaction with the diazonaphthoquinonesulfonic acid chloride include 2,2′-bis (4-hydroxyphenyl) propane, bis (p-hydroxyphenyl) methane, and 2,2′-bis (4 -Hydroxyphenyl) hexafluoropropane, bis (4-hydroxyphenyl) sulfone, 1,1,1-tris (4-hydroxyphenyl) ethane, 4,4 ', 4 "-trihydroxytriphenylmethane, α, α , Α′-tris (4-hydroxyphenyl) -1-ethyl-4-isopropylbenzene, and the like.

上記ナフトキノンジアジド系の化合物は、それ自身はアルカリ水溶液に対して難溶性を示す化合物であるが、紫外線等の活性光線による露光でカルボキシル基が生成されアルカリ水溶液に対して易溶になる。 Specific examples of the naphthoquinone diazide photosensitizer include the following.

The naphthoquinonediazide-based compound itself is a compound that is hardly soluble in an alkaline aqueous solution, but a carboxyl group is generated by exposure with an actinic ray such as ultraviolet rays, and becomes easily soluble in an alkaline aqueous solution.

  Examples of the (C) solvent used in the present invention include aprotic polar solvents such as N-methylpyrrolidone, N, N′-dimethylacetamide, N, N′-dimethylformamide, cyclohexanone, cyclopentanone, γ- Butyrolactone, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl lactate, ethyl lactate, butyl lactate and the like can be used, and these can be used alone or in combination.

  Next, the usage method of the resin composition obtained by this invention is demonstrated.

  When considering application to a semiconductor device, first, the resin composition is coated on a target wafer using a spin coater, and then the coating film is dried at 90 to 140 ° C. The obtained coating film is transmitted through a mask on which a pattern is drawn and irradiated with active ultraviolet rays such as i-line (365 nm) and g-line (436 nm). Next, as a developing solution, for example, quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide, amine-based alkaline aqueous solutions such as ethylamine, n-propylamine and choline, or sodium hydroxide, potassium hydroxide, Examples thereof include inorganic alkalis such as sodium carbonate, and these can be used alone or in combination of two or more. Using these aqueous solutions, only the ultraviolet irradiation part is dissolved and developed, rinsed with pure water, and dried by spin drying. As a developing method, methods such as spraying, paddle, dipping, and ultrasonic waves can be considered. Thereby, a desired positive pattern can be obtained on the target wafer. Furthermore, a thermosetting reaction is performed by heat-treating this coating film at 150 to 300 ° C., and a coating film having excellent heat resistance and chemical resistance can be formed.

  That is, the greatest feature of the present invention is that, as a result of extensive research conducted by the present inventor, naphthoquinone diazide photosensitization in which (A) the phenol resin having a methylol group and (B) naphthoquinone diazide sulfonic acid chloride are esterified. By using an agent, it is possible to process a positive pattern by ultraviolet exposure such as i-line (365 nm) and development using an aqueous alkali solution, and (A) between the methylol group and the methylol group of the phenol resin by heat treatment. A cross-linking reaction is performed to produce a strong coating film with improved heat resistance and chemical resistance.

  In the above method of use, the resin composition of the present invention is subjected to spin coating and drying on the substrate, and then irradiated with actinic rays such as ultraviolet rays on the coating film to sensitize the naphthoquinonediazide photosensitizer of the active light irradiation part. The agent changes to a structure capable of alkali development. Next, in the development with an aqueous alkali solution, in the exposed area, (A) the phenol part in the structure of the phenol resin is dissolved by the aqueous alkali solution, and at the same time, the dissolution is promoted by the naphthoquinone diazide photosensitizer having the above formulas 7 and 8. In the unexposed area, (B) naphthoquinone diazide-based photosensitizer and (A) the phenol moiety of the phenol resin are azo coupling or sulfonic acid with the diazo group in the formula 7,8 (naphthoquinone diazide sulfonic acid chloride). A positive pattern can be formed by inhibiting dissolution in an alkaline aqueous solution by hydrogen bonding with a group and reducing solubility. In addition, as described above, the heat treatment after pattern formation causes a cross-linking reaction between the methylol groups in the (A) component phenol resin of the present invention, so compared with a phenol resin having no methylol groups. Thus, a coating film having high heat resistance and chemical resistance can be obtained.

  EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not restrict | limited to these Examples.

  Establish 1,2-naphthoquinone-2-diazide-5-sulfonic acid in α, α, α'-tris (4-hydroxyphenyl) -1-ethyl-4-isopropylbenzene in a reaction flask equipped with a nitrogen inlet tube The reacted phenol compound is put into a 30 parts by weight flask, and 130 parts by weight of N-methyl-2-pyrrolidone as a solvent is added and stirred for 1 hour to dissolve. Next, as a phenol resin having a methylol group, a resin having the structural formula of Formula 4 described above, having a number average molecular weight of 5000, and a ratio of n to n ′ of n <10 mol% or less and n ′> 90 mol% or more. Is put into a flask over 100 parts by weight for 30 minutes. The resin is dissolved by stirring for 10 hours. At that time, an ice bath is set and dissolved at a liquid temperature of 5 ° C. or higher and 30 ° C. or lower. This solution was filtered through a 1 μm filter to obtain Sample 1.

The sample 1 was coated on a 4-inch silicon wafer using a spin coater and dried by heating at 130 ° C. for 4 minutes on a baking plate to obtain a coating film having a thickness of 7 μm. This coating film was irradiated with a test pattern by changing the exposure energy with an ultraviolet exposure machine using a filter that transmits only i-line (365 nm), and then paddle development for 3 minutes with a 2.38% aqueous solution of tetramethylammonium hydroxide. , Washed with pure water, and spin-dried. By this operation, a positive pattern in which the ultraviolet irradiation part of the coating film was dissolved could be obtained. A good pattern was formed at an exposure amount of 250 mj / cm ² , and when the obtained pattern was observed with an optical microscope, it was confirmed that a pattern of up to 5.0 μm was formed sharply.

  When this film was heat-treated at 100 ° C., 120 ° C., 140 ° C., 160 ° C., and 260 ° C. for 1 hour, a 5 μm thick coating film was formed. Based on JIS-K-5400, this coating film was cut into 1 mm □ × 100 grids, a cellophane tape was applied, and then peeled off to confirm the adhesion of the coating film. There wasn't. Thus, the pattern adhered firmly on the silicon wafer, and no resin cracks were found in the pattern.

  In a reaction flask equipped with a nitrogen introduction tube, a phenol compound obtained by ester-reaction of 2,3,4,4′-tetrahydroxybenzophenone with 1,2-naphthoquinone-2-diazide-5-sulfonic acid was added to a 30 part by weight flask. Then, 130 parts by weight of N-methyl-2-pyrrolidone is added as a solvent and stirred for 1 hour to dissolve. Next, as a phenol resin having a methylol group, a resin having the structural formula of Formula 5 described above, having a number average molecular weight of 8000, and a ratio of n to n ′ of n <30 mol% or less and n ′> 70 mol% or more. Is gradually put into the flask over 100 parts by weight over 30 minutes. The resin is dissolved by stirring for 10 hours. At that time, an ice bath is set and dissolved at a liquid temperature of 5 ° C. or higher and 30 ° C. or lower. This solution was filtered through a 1 μm filter to obtain sample 2.

The sample 2 was coated on a 4-inch silicon wafer using a spin coater and dried by heating at 130 ° C. for 6 minutes on a baking plate to obtain a coating film having a thickness of 7 μm. This coating film was irradiated with a test pattern by changing the exposure energy with an ultraviolet exposure machine using a filter that transmits only i-line (365 nm), and then paddle development for 4 minutes with a 2.38% aqueous solution of tetramethylammonium hydroxide. , Washed with pure water, and spin-dried. By this operation, a positive pattern in which the ultraviolet irradiation part of the coating film was dissolved could be obtained. A good pattern was formed at an exposure amount of 300 mj / cm ² , and when the obtained pattern was observed with an optical microscope, it was confirmed that a pattern of up to 5.0 μm was formed sharply.

  When this film was heat-treated at 100 ° C., 120 ° C., 140 ° C., 160 ° C., and 260 ° C. for 1 hour, a 5 μm thick coating film was formed. Based on JIS-K-5400, this coating film was cut into 1 mm □ × 100 grids, a cellophane tape was applied, and then peeled off to confirm the adhesion of the coating film. There wasn't. Thus, the pattern adhered firmly on the silicon wafer, and no resin cracks were found in the pattern.

を示し、数平均分子量５０００である樹脂を１００重量部、３０分かけて徐々にフラスコに投入する。樹脂の溶解には１０時間攪拌して溶解させるが、その際にアイスバスをセットして５℃以上、３０℃以下の液温で溶解させる。この溶液を１ｕｍフィルターにて濾過し、サンプル３とした。 Comparative Example 1
Establish 1,2-naphthoquinone-2-diazide-5-sulfonic acid in α, α, α'-tris (4-hydroxyphenyl) -1-ethyl-4-isopropylbenzene in a reaction flask equipped with a nitrogen inlet tube The reacted phenol compound is put into a 30 parts by weight flask, and 130 parts by weight of N-methyl-2-pyrrolidone as a solvent is added and stirred for 1 hour to dissolve. Next, as a phenolic resin having no methylol group, the following structural formula

The resin having a number average molecular weight of 5000 is gradually charged into the flask over 100 parts by weight over 30 minutes. The resin is dissolved by stirring for 10 hours. At that time, an ice bath is set and dissolved at a liquid temperature of 5 ° C. or higher and 30 ° C. or lower. This solution was filtered through a 1 um filter to obtain Sample 3.

This sample 3 was coated on a 4-inch silicon wafer using a spin coater and dried by heating at 130 ° C. for 4 minutes on a baking plate to obtain a coating film having a thickness of 7 μm. This coating film was irradiated with a test pattern by changing the exposure energy with an ultraviolet exposure machine using a filter that transmits only i-line (365 nm), and then paddle development for 3 minutes with a 2.38% aqueous solution of tetramethylammonium hydroxide. , Washed with pure water, and spin-dried. By this operation, a positive pattern in which the ultraviolet irradiation part of the coating film was dissolved could be obtained. A good pattern was formed at an exposure amount of 200 mj / cm ^{2. When} the obtained pattern was observed with an optical microscope, it was confirmed that a pattern of up to 5.0 μm was formed sharply.

  This film was heated at 100 ° C., 120 ° C., 140 ° C., 160 ° C., and 260 ° C. for 1 hour, but the pattern melted and the opening was crushed and filled with resin. The pattern was crushed, but this film was cut into 1 mm □ × 100 grids based on JIS-K-5400, and cellophane tape was applied and then peeled off to confirm the adhesion of the film. All the coatings were peeled off.

を示し、数平均分子量８０００である樹脂を１００重量部、３０分かけて徐々にフラスコに投入する。樹脂の溶解には１０時間攪拌して溶解させるが、その際にアイスバスをセットして５℃以上、３０℃以下の液温で溶解させる。この溶液を１μｍフィルターにて濾過し、サンプル４とした。 Comparative Example 2
In a reaction flask equipped with a nitrogen introduction tube, a phenol compound obtained by ester-reaction of 2,3,4,4′-tetrahydroxybenzophenone with 1,2-naphthoquinone-2-diazide-5-sulfonic acid was added to a 30 part by weight flask. Then, 130 parts by weight of N-methyl-2-pyrrolidone is added as a solvent and stirred for 1 hour to dissolve. Next, as a phenolic resin having no methylol group, the following structural formula

The resin having a number average molecular weight of 8000 is gradually put into the flask over 100 parts by weight over 30 minutes. The resin is dissolved by stirring for 10 hours. At that time, an ice bath is set and dissolved at a liquid temperature of 5 ° C. or higher and 30 ° C. or lower. This solution was filtered through a 1 μm filter to obtain sample 4.

This sample 4 was coated on a 4-inch silicon wafer using a spin coater and dried by heating at 130 ° C. for 6 minutes on a baking plate to obtain a coating film having a thickness of 7 μm. This coating film was irradiated with a test pattern by changing the exposure energy with an ultraviolet exposure machine using a filter that transmits only i-line (365 nm), and then paddle development for 4 minutes with a 2.38% aqueous solution of tetramethylammonium hydroxide. , Washed with pure water, and spin-dried. By this operation, a positive pattern in which the ultraviolet irradiation part of the coating film was dissolved could be obtained. A good pattern was formed at an exposure amount of 150 mj / cm ^{2. When} the obtained pattern was observed with an optical microscope, it was confirmed that a pattern of up to 5.0 μm was formed sharply.

  This film was heated at 100 ° C., 120 ° C., 140 ° C., 160 ° C., and 260 ° C. for 1 hour, but the pattern melted and the opening was crushed and filled with resin. The pattern was crushed, but this film was cut into 1 mm □ × 100 grids based on JIS-K-5400, and cellophane tape was applied and then peeled off to confirm the adhesion of the film. All the coatings were peeled off.

Claims (2)

(A) A phenol resin having a methylol group represented by the following general formula

(Wherein, m is an integer of 1 to 2, n and n ′ are integers of 1 or more) or

(In the formula, m is an integer of 1 to 2, and n and n ′ are integers of 1 or more.)
Is a positive photosensitive resin composition characterized by comprising an essential component. (A) a phenolic resin having a methylol group represented by the following general formula:

(Wherein, m is an integer of 1 to 2, n and n ′ are integers of 1 or more) or

(In the formula, m is an integer of 1 to 2, and n and n ′ are integers of 1 or more.)
(B) Naphthoquinonediazide sulfonic acid chloride represented by the following general formula

A positive photosensitive resin composition comprising a compound obtained by esterifying a phenolic compound and a solvent (C) as essential components.