JP2000131844A - Positive photosensitive resin composition and semiconductor device made by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive composition high in sensitivity by applying a specified composition and exposing it in specified conditions and developing it in an aqueous solution of tetramethylammonium hydroxide in a specified percentage for a specified sec and specifying the range of the dissolution velocity of unexposed parts and that of the difference of the exposed parts and the unexposed parts. SOLUTION: The composition composed essentially of polybenzooxazole precursor represented by formula I is applied to a film thickness of 10±1 μm measured after prebaking it at 120 deg.C for 4 min, and after the prebaking, exposed in the conditions of 300 mj/cm2, and developed in an aqueous solution of 2.38% tetramethylammonium hydroxide for 80 sec, and at that time, the dissolution velocity in the unexposed parts is 0-180 μm/hr and the difference between that of the exposed parts and that of the unexposed parts is 270-460 μm/hr. In formula I, X is a tetravalent cyclic group; Y is a divalent cyclic group; each of R1 and R2 is a divalent organic group; each of R3 and R4 is a monovalent organic group; Z is a group of formula II; E is an aliphatic group having an alkenyl group or the like; (a) is 60.0-100.0 mol%; (b) is 0-40 mol%; and (n) is 2-500.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive photosensitive resin composition having a low dissolution rate in an unexposed portion and a high sensitivity, and a semiconductor device using the same.

[0002]

2. Description of the Related Art Hitherto, polyimide having excellent heat resistance, electric characteristics, mechanical characteristics, and the like has been used as a surface protective film or an interlayer insulating film of a semiconductor element. In recent years, high integration of semiconductor elements, enlargement of chips, thinning and miniaturization of packages, transition to a surface mounting method by solder reflow, and the like have been remarkably progressing. Along with this, even for resins for surface protective films and interlayer insulating films, heat cycle resistance,
Further improvement in heat shock resistance and the like has been required. On the other hand, recently, a technique of photosensitizing polyimide has attracted attention. For example, a negative photosensitive polyimide represented by the following formula (2) has been developed.

[0003]

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When this resin is used, the number of pattern forming steps can be reduced, so that the production yield can be improved. However, when developing this resin, N-methyl-
Since a solvent such as 2-pyrrolidone is required, there are problems in safety and handling. In view of such a situation, a new photosensitive resin composition instead of polyimide has recently been developed. For example, in Japanese Patent Publication No. 1-46862, a polybenzoxazole precursor or a resin thereof,
A positive photosensitive resin composition comprising a diazoquinone compound is disclosed. This resin composition can be developed not only with an aqueous alkali solution, but also with excellent heat resistance, electrical properties,
It has mechanical properties and excellent fine workability.

[0005] The developing mechanism of this positive photosensitive resin composition is considered as follows. That is, the unexposed portion of the diazoquinone compound is insoluble in the alkaline aqueous solution. However, the diazoquinone compound in the exposed area undergoes a chemical change,
It becomes soluble in alkaline aqueous solution. By developing using the difference in solubility between the exposed portion and the unexposed portion, it is possible to form a coating film pattern in which only the unexposed portion remains.

When these photosensitive resin compositions are used in semiconductor devices, a particular problem is the sensitivity of the photosensitive resin composition. If the sensitivity is low, to give enough light,
It is necessary to lengthen the exposure time per wafer,
There is a problem that the throughput of the semiconductor device manufacturing process is reduced.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a positive photosensitive resin composition having high sensitivity and a semiconductor device using the same.

[0008]

According to the present invention, a positive photosensitive resin composition mainly comprising a polybenzoxazole precursor has a thickness of 1 after prebaking at 120 ° C. for 4 minutes.
Coating was performed so as to have a thickness of 0 ± 1 μm, prebaking was performed under the above conditions, and exposure was performed under the conditions of 300 mj / cm ² , and 2.38
8% aqueous solution of tetramethylammonium hydroxide
When developed for 0 seconds, the dissolution rate of the unexposed portion is 0 to 180 μm
m / hr, the difference in dissolution rate between the exposed and unexposed areas was 27
An object of the present invention is to obtain a positive photosensitive resin composition of 0 to 460 μm / hr and a semiconductor device using the same. The polybenzoxazole precursor used in the present invention is represented by the general formula (1).

[0009]

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The polybenzoxazole precursor of the formula (1) comprises a bisphenol having a structure of X, a dicarboxylic acid having a structure of Y, a terminal treating agent having a structure of E,
If necessary, a modifier having a structure of Z is formed. When the polybenzoxazole precursor is heated at a temperature of about 300 to 400 ° C., the ring closes and changes to polybenzoxazole having high heat resistance. Examples of X in the formula (1) include, but are not particularly limited to, the following.

[0011]

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In addition, examples of Y in the formula (1) include, but are not limited to, the following.

[0013]

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Examples of E in the formula (1) include, but are not particularly limited to, the following.

[0015]

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Further, examples of Z in the formula (1) include, but are not limited to, the following.

[0017]

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The positive photosensitive resin composition of the present invention is mainly composed of a polybenzoxazole precursor represented by the general formula (1) and a positive photosensitive agent.

The positive photosensitive agent is a diazoquinone compound having a 1,2-benzoquinonediazide or 1,2-naphthoquinonediazide structure. These are disclosed in U.S. Pat. Nos. 2,772,972 and 2,797,21.
No. 3,669,658. For example, the following are mentioned.

[0020]

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[0021]

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The positive photosensitive resin composition of the present invention may optionally contain a dihydropyridine derivative for enhancing the photosensitive characteristics. Examples of the dihydropyridine derivative include 2,6-dimethyl-3,5-diacetyl-
4- (2'-nitrophenyl) -1,4-dihydropyridine, 4- (2'-nitrophenyl) -2,6-dimethyl-3,5-dicarbethoxy-1,4-dihydropyridine, 4- (2 ', 4'-Dinitrophenyl) -2,6
-Dimethyl-3,5-carbomethoxy-1,4-dihydropyridine and the like.

The positive photosensitive resin composition of the present invention employs various methods for improving the solubility of exposed portions during development in order to enhance the sensitivity characteristics. The simplest method is to improve the processing method of the positive photosensitive resin composition. The solubility is improved by relaxing the prebaking conditions of the positive photosensitive resin composition. This method is practical and in practice. However, in this method, it is preferable that the solubility of the exposed portion is increased. However, since the film loss of the non-exposed portion is increased, a problem that the pattern is deformed may occur.

As the next method, improvement of the polybenzoxazole precursor itself in the positive photosensitive resin composition has been performed. That is, this is a method of increasing the solubility by incorporating a highly soluble functional group into the structure or at the terminal of the polybenzoxazole precursor or reducing the molecular weight of the polybenzoxazole precursor. This method is also effective, but similarly to the above-mentioned method, the film loss in the non-exposed portion is increased, and thus a problem such that the pattern shape is lost may occur.

The most effective method is to incorporate a dissolution accelerator as one component of the positive photosensitive resin composition. Various dissolution promoters are known, and examples thereof include the following phenolic compounds. However, it is not particularly limited to these.

[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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When a phenolic compound is added to the positive photosensitive resin composition, the solubility of the exposed area is increased and the sensitivity is improved. Conversely, the solubility of the unexposed portions is reduced, the film loss is reduced, and an ideal pattern is formed.

It is already known to incorporate a phenol compound into a positive resist composition. For example, JP-A-3-
JP-A-200251, JP-A-3-200252,
JP-A-3-200253, JP-A-3-20025
No. 4, JP-A-4-1650, JP-A-4-16
No. 51, JP-A-4-11260, JP-A-4-11260
No. 12356, Japanese Unexamined Patent Publication No. Hei 4-12357, and the like.

However, even if the phenolic compounds disclosed therein are blended with the positive photosensitive resin composition mainly comprising the polybenzoxazole precursor of the present invention,
No effect of improving sensitivity was obtained.

The positive photosensitive resin composition using a polybenzoxazole precursor according to the present invention has a dissolution rate of 0 to 180 μm / hr in an unexposed part and a difference in dissolution rate between an exposed part and an unexposed part. Is preferably 270 to 460 μm / hr. Dissolution rate of unexposed part during development is 180 μm / hr
If it is larger, the final residual film pattern is deformed, which is a problem. The difference in dissolution rate between exposed and unexposed areas is 270 μm /
A value of less than hr is a problem because the dissolution rate of the exposed portion is too low, resulting in poor penetration and poor sensitivity.

The positive photosensitive resin composition of the present invention may further contain additives such as an adhesion aid and a leveling agent, if necessary. These components are dissolved in a solvent and used in the form of a varnish. As the solvent, N-methyl-2-
Pyrrolidone, γ-butyrolactone, N, N-dimethylacetamide, dimethylsulfoxide, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl lactate, ethyl lactate, Butyl lactate, methyl-1,3-butylene glycol acetate, 1,3-butylene glycol-3-monomethyl ether, methyl pyruvate, ethyl pyruvate,
Methyl-3-methoxypropionate or the like is used alone or in combination.

The highly sensitive positive photosensitive resin composition of the present invention is used in a semiconductor device by the following method. First, the composition is applied to a silicon wafer on which a semiconductor circuit is baked. Examples of the coating method include spin coating with a spinner, spray coating with a spray coater, or dipping, printing, roll coating, or the like.
The coating amount is such that the film thickness after curing is 0.1 to 20 μm. When the film thickness is less than 0.1 μm, it is difficult to sufficiently exert a function as a surface protective film of a semiconductor element,
If it is thicker than 20 μm, it becomes difficult to obtain a fine pattern.

Next, after pre-baking at 60 to 120 ° C. and pre-drying, a desired pattern shape is exposed and irradiated with actinic radiation. As the actinic radiation, X-rays, electron beams, ultraviolet rays, visible rays and the like can be used. Next, a relief pattern is obtained by dissolving and removing the exposed / irradiated portion with a developing solution.

Examples of the developer include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia;
Primary amines such as ethylamine and n-propylamine;
Secondary amines such as diethylamine and di-n-propylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide and the like An aqueous solution of an alkali such as a quaternary ammonium salt or an aqueous solution obtained by adding an appropriate amount of a water-soluble organic solvent such as an alcohol such as methanol or ethanol or a surfactant thereto can be used.

As a developing method, a system such as spray, paddle, immersion, and ultrasonic wave can be used. Next, the relief pattern formed by development is rinsed. Distilled water is used as the rinsing liquid. Next, a heat treatment is performed to close the ring to form an oxazole ring, thereby obtaining a final pattern having high heat resistance.

The positive photosensitive resin composition of the present invention can be used not only as a surface protective film for a semiconductor, but also for an interlayer insulating film of a semiconductor, an interlayer insulating film of a multilayer circuit board, a cover coat film of a flexible copper clad board, and a solder resist. It is also useful as a film or a liquid crystal alignment film.

[0043]

The present invention will be described below in detail with reference to examples. << Example 1 >> * Synthesis of polybenzoxazole precursor 443.2 g (0.93) of a dicarboxylic acid derivative obtained by reacting 1 mol of diphenyl ether-4,4'-dicarboxylic acid with 2 mol of 1-hydroxybenzotriazole. Mol) and hexafluoro-2,2-bis (3-amino-
366.3 g of 4-hydroxyphenyl) propane (1.
0 mol) in a four-necked flask equipped with a stirrer, a thermometer, a raw material inlet, and a cooling tube with a dry nitrogen gas inlet tube.
After adding and dissolving 3000 g of N-methyl-2-pyrrolidone, the mixture was stirred and reacted at 75 ° C. for 12 hours. Then N
32.8 g of 5-norbornene-2,3-dicarboxylic dianhydride dissolved in 500 g of -methyl-2-pyrrolidone
(0.2 mol), and the mixture was further stirred for 12 hours to complete the reaction. After the reaction mixture was filtered, water / methanol (3 /
Put into the solution of 1). Thereafter, the precipitate was collected, sufficiently washed with water, and dried under vacuum to obtain a target polybenzoxazole precursor.

* Preparation of Positive Photosensitive Resin Composition 100 parts by weight of the polybenzoxazole precursor, 25 parts by weight of a diazoquinone compound (Q) having the following structural formula, and a phenol compound (P-1) 10 having the following structural formula A part by weight was dissolved in 250 parts by weight of N-methyl-2-pyrrolidone, and then filtered through a 0.2 μm Teflon filter to obtain a positive photosensitive resin composition.

[0045]

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[0046]

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* Evaluation of dissolution rate The positive photosensitive resin composition was applied on a silicon wafer by using a spin coater, and then dried in an oven at 120 ° C for 4 minutes to form a coating film having a thickness of 10.1 µm. Obtained. This coating film was exposed to 300 mJ / cm ² using a stepper. Next, the film was immersed in a developer of an aqueous solution of tetramethylammonium hydroxide (2.38%) for 80 seconds, and then rinsed with pure water for 30 seconds. As a result, the film thickness of the unexposed portion was reduced to 8.5 μm, and the film of the exposed portion was completely disappeared. Since the amount of reduction in the thickness of the unexposed portion is 1.6 μm, the dissolution rate is (1.6 μm / 80 sec) × 60 × 60 = 7.
It was as small as 2 μm / hr. Also, since the amount of reduction in the film thickness of the exposed portion was 10.1 μm, the dissolution rate was (10.
1 μm / 80 sec) × 60 × 60 = 454 μm / hr
And the difference in dissolution rate between the exposed and unexposed areas is 454-
72 = 382 μm / hr, which was very large and excellent.

* Evaluation of Sensitivity The positive photosensitive resin composition was applied on a silicon wafer using a spin coater, and then dried in an oven at 120 ° C. for 4 minutes to obtain a coating film having a thickness of 10.2 μm. Was. Using a stepper, apply 50 mJ / cm ² to 5
Exposure was performed every 10 mJ / cm ² up to 40 mJ / cm ² . Next, it was immersed in a developer of an aqueous solution of tetramethylammonium hydroxide (2.38%) for 120 seconds to dissolve and remove the soluble portion, and then rinsed with pure water for 30 seconds. As a result, a pattern was formed from a portion where the exposure amount was 290 mJ / cm ² . That is, the sensitivity was excellent at 290 mJ / cm ² .

Example 2 A positive photosensitive resin composition was prepared by changing the phenol compound (P-1) in Example 1 to a phenol compound (P-2) having the following structural formula, and evaluated in the same manner. Was done. As a result, the dissolution rate of the unexposed portion was as small as 95 μm / hr, which was excellent, and the difference between the dissolution rates of the exposed portion and the unexposed portion was as large as 360 μm / hr, which was excellent. The sensitivity was as excellent as 240 mJ / cm ² .

[0050]

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Comparative Example 1 A positive photosensitive resin composition to which the phenol compound (P-1) in Example 1 was not added was prepared, and the same evaluation was performed. As a result, the dissolution rate of the unexposed portion was as small as 63 μm / hr, and the difference between the dissolution rates of the exposed portion and the unexposed portion was as small as 250 μm / hr.

Comparative Example 2 A positive photosensitive resin composition was prepared by changing the phenol compound (P-1) in Example 1 to a phenol compound (P-3) having the following structural formula, and evaluated in the same manner. Was done. As a result, the dissolution rate of the unexposed portion was as large as 227 μm / hr, and the difference between the dissolution rate of the exposed portion and the unexposed portion was as small as 227 μm / hr. There was no.

[0053]

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[0054]

According to the present invention, a positive photosensitive resin composition mainly composed of a polybenzoxazole precursor has a large difference in dissolution rate between an exposed portion and an unexposed portion due to a high dissolution rate in an exposed portion. Since the object has high sensitivity, a semiconductor device can be obtained with high throughput.

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Claims (2)

[Claims] The positive photosensitive resin composition mainly comprising a polybenzoxazole precursor represented by the general formula (1) has a thickness of 10 after prebaking at 120 ° C. for 4 minutes.
Coating was performed so as to be ± 1 μm, and after pre-baking under the above conditions, exposure was performed under the condition of 300 mj / cm ² , and 2.38%
80 in aqueous tetramethylammonium hydroxide solution
When developed for 2 seconds, the dissolution rate of the unexposed area is 0 to 180 μm
/ Hr, the difference in dissolution rate between the exposed and unexposed areas is 270
A positive-type photosensitive resin composition having a thickness of from about 460 μm / hr to about 460 μm / hr. Embedded image 2. A semiconductor obtained by applying the positive photosensitive resin composition according to claim 1 so that the film thickness after heating and curing becomes 0.1 to 20 μm, prebaking, exposing, developing and heating. A semiconductor device obtained from an element.