JPH01293341A - Positive type photosensitive composition - Google Patents

Abstract

PURPOSE:To improve long-term preservation stability and fine pattern formability by dissolving a positive type photosensitive compd. having a quinonediazide group and a coated film forming material into ethyleneglycol monoisopropyl ether acetate thereby forming the above compsn. CONSTITUTION:This compsn. is formed by dissolving the positive type photosensitive compd. having the quinonediazide group and the coated film forming material into the ethyleneglycol monoisopropyl ether acetate. The positive type photosensitive compd. having the quinonediazide group is exemplified by the resultant reaction product of, for example, orthoquinone diazide sulfonyl chloride and a hydroxyl group or a compd. having an amino group. The coated film forming material is exemplified preferably by a cresol novolak resin, i.e., the resin obtd. from a mixture compsn. of 10-45wt.% m-cresol and 90-55wt.% p-cresol. The ethyleneglycol monoisopropyl ether acetate has high dissolving power, suppresses the recrystallization of the photosensitive compd. and has excellent stability. The long-term preservation stability and fine pattern formability are thereby improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel positive-working photosensitive composition. More specifically, the present invention relates to a positive photosensitive composition having excellent storage stability and fine pattern forming properties.

2. Description of the Related Art Generally, a positive photosensitive composition is used as a solution in which a photosensitive compound and a film-forming material are dissolved in a suitable solvent.

As the photosensitive compound in this positive photosensitive composition, a quinonediazide group-containing compound having, for example, an orthobenzoquinonediazide group, an orthonaphthoquinonediazide group, an orthoanthraquinonediazide group, etc., is usually used. These quinonediazide group-containing compounds are
It is suitable as a positive-working photosensitive compound because it is easily photodecomposed by irradiation with actinic rays to produce a carboxylic acid and is converted into a substance soluble in an alkaline solution. However, these diazide groups lack stability and are usually used in 1.
Like 2-naphthoquinonediazide-5-sulfonate, it is stabilized and used by forming an ester with a phenolic hydroxyl group.

In addition, when a solution is prepared by dissolving the above-mentioned positive photosensitive compounds and film-forming materials in a solvent, the solution may decompose during storage and the photosensitivity may decrease, or the photosensitivity may decrease once dissolved. The disadvantage is that the chemical compound recrystallizes and precipitates, impairing the uniformity of the solution. For the stability of a solution, the interaction between the solute and the solvent is one of the important factors, and it is necessary that the solvent has a large solute-dissolving power and that the solute is kept stable for a long period of time. be.

The solvent in the positive photosensitive composition has a strong dissolving power for both the photosensitive compound and the coating film forming material,
It is important to form a uniform solution regardless of its concentration and to provide a uniform and smooth coating film. Such solvents are selected as appropriate depending on the type of solvent, but since many quinonediazide group-containing compounds are generally poorly soluble, solvents such as methylpyrrolidone, cyclopentanone, cyclohexanone, and ethylene glycol monomers are recommended. Only specific ones such as ethyl ether acetate, ethoxypropyl acetate, etc. can be used.

However, methylpyrrolidone, cyclopentanone,
In photosensitive compositions using cyclohexanone as a solvent, the photosensitive compound gradually decomposes during storage, resulting in a decrease in photosensitivity, and this solvent is expensive, making it unsuitable for practical use. It is. Furthermore, in photosensitive compositions using ethylene glycol monoethyl ether acetate and ethoxypropyl acetate as solvents, the photosensitive compound tends to precipitate as crystals during long-term storage; If this method is used, crystals will form on the substrate, which will have an adverse effect on the formation of fine patterns, so the range of use will inevitably be limited.

Therefore, in this technical field, there has been a strong desire for a stable positive-working photosensitive composition that does not reduce photosensitivity even after long-term storage and is capable of forming a uniform and smooth coating film.

Problems to be Solved by the Invention The present invention has been made in response to such demands and for the purpose of providing a positive photosensitive composition having excellent long-term storage stability and fine pattern forming properties.

Means for Solving the Problems The inventors have found that the present inventors have developed a system that exhibits good stability over long periods of time.
As a result of intensive research to develop a positive photosensitive composition suitable for forming fine patterns, it was discovered that the purpose could be achieved by using ethylene glycol monoisopropyl ether acetate as a solvent, and this knowledge Based on this, the present invention was completed.

That is, the present invention uses ethylene glycol monoisopropyl ether acetate as a positive type photosensitive compound having a quinone diazide group and as a coating film forming material.

The present invention will be explained in detail below.

Examples of the positive photosensitive compound having a quinonediazide group used in the composition of the present invention include orthobenzoquinonediazide, orthonaphthoquinonediazide, orthoanthraquinonediazide, and derivatives thereof, such as orthoquinonediazide sulfonyl chloride and a compound having a hydroxyl group or an amino group. Examples include reaction products of.

Examples of compounds having this hydroxyl group or amino group include
f, 2,3.4-t-lyhydroxybenzophenone, 2
, 2', 4.4'-polyhydroxybenzophenones such as tetrahydroxybenzophenone, phenol, p-methoxyphenol, dimethylphenol, hydroquinone, bisphenol A1 naphthol, pyrocatechol, pyrogallol, pyrogallol monomethyl ether, pyrogallol-1,3-dimethyl ether , gallic acid, esterified or etherified gallic acid with some hydroxyl groups remaining, aniline, p-aminodiphenylamine, phenol resin, etc. can be used. The photosensitive compounds are usually used alone, but two or more types can also be used in combination.

Further, as the coating film forming material used in the composition of the present invention, alkali-soluble resins are preferable, such as novolak resins produced by condensing phenol or cresol with aldehydes, polyvinyl alcohol, polyvinyl alkyl ether, Examples include copolymers of styrene and acrylic acid, copolymers of methacrylic acid and alkyl methacrylates, polymers of hydroxystyrene, polyvinylhydroxybenzoate, and polyvinylhydroxybenzal. One type of these coating film forming materials may be used, or two or more types may be used in combination.

Among these film-forming materials, preferred are:
Cresol novolak resin, specifically m-cresol 10-45% by weight and p-cresol 90-55% by weight
Examples include those obtained from cresol mixed with A positive photosensitive composition using such Talesol novolac resin as the coating film forming material is practical because it can form an excellent resist pattern.

The ratio of the photosensitive compound to the coating film-forming material used is usually selected within the range of 1:1 to 1:10 by weight. When the positive photosensitive compound is bonded to, for example, a phenol resin, and the positive photosensitive compound serves both as the photosensitive compound and the coating film forming material, this ratio may be regarded as the same amount of both. If the amount of the coating film-forming material exceeds this ratio, it is undesirable because it will cause a deterioration in the fidelity of the mask pattern of the resulting image and a decrease in transferability, and if it is less than this ratio, the strength and uniformity of the formed coating film will deteriorate. It also causes a decrease in image quality and resolution.
; It is not preferable because it is free. A generally preferred blending ratio of photosensitive compound to coating film forming material is in the range of 1:2.5 to 1:5.5 by weight.

In the composition of the present invention, ethylene glycol monoisopropyl ether acetate is used as a solvent.

This organic solvent has never been used as a solvent for positive photosensitive compositions, and the amount used is as follows:
There is no particular restriction as long as it can be applied to the coated substrate to form a uniform thin film layer, but usually the total solid content, that is, the total amount of the positive photosensitive compound and the coating film forming material, is within the range of the composition. It is used in an amount ranging from 3 to 50% by weight based on the total weight. If the solid content is less than 3% by weight, it is undesirable because the residual film rate in unexposed areas will decrease, and if it exceeds 50% by weight, there will be a tendency for the sensitivity to decrease or for development to be left behind during development. Therefore, it is undesirable.

This ethylene glycol monoisopropyl ether acetate has a large dissolving power, suppresses recrystallization of photosensitive compounds, and has excellent stability, so it is useful as a preparation solvent for photosensitive compositions and has not been used conventionally. Unlike the various solvents used, it is characterized by low toxicity, making it extremely useful in practical terms.

The compositions of the present invention may also contain, for example, sensitizers, other additional resins, plasticizers, stabilizers, or colorants to make the formed image more visible, as well as other materials commonly used in the art. Various additives can be included.

When high resolution is required, such as when using photoresist for manufacturing hard masks, the film thickness of the photoresist is set to 0.
It is preferable to adjust the solid content to about 2 μm, but if the composition of the present invention is used, the solid content concentration will be 3 to 5% by weight and the rotation rate will be 3,000 rpm.
All you have to do is spin code at the rotation speed of Otori. In addition, when it is necessary to coat a substrate with large steps, the conventional method uses a so-called multilayer resist method in which the photosensitive composition is applied after filling the recesses, but the composition of the present invention With this method, there is almost no increase in viscosity even when the solid content is at a high concentration of 40 to 50% by weight, so spin cording is possible. A thick film of about 3 μm can be obtained by simply spin-coding a certain substrate, and a fine pattern with high resolution can be formed on a substrate with steps.

Next, to give an example of a preferred method of using the composition of the present invention, first, a positive photosensitive compound and a film-forming material are dissolved in ethylene glycol monoisopropyl ether acetate on a support such as a silicon wafer. A photoresist is formed by applying the prepared positive photosensitive composition using a spin coater or the like and then drying it.

Next, using a light source that emits ultraviolet rays, such as a low-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, arc lamp, or xenon lamp, exposure is performed through a required mask pattern, or irradiation is performed while scanning an electron beam. Next, when this is immersed in a developing solution, for example a weakly alkaline aqueous solution such as a 1 to 2% by weight aqueous sodium hydroxide solution, the portions made solubilized by exposure are selectively dissolved and removed, resulting in a positive type that is faithful to the mask pattern. An image is obtained.

Effects of the invention Compared to conventional compositions, the positive photosensitive composition of the present invention has
Ethylene glycol monoisopropyl ether acetate has extremely good stability, and has very weak decomposition or decomposition-promoting power for positive-working photosensitive compounds, so the photosensitive properties of positive-working photosensitive compounds do not deteriorate and it remains stable even after long-term storage. Able to maintain high resolution. Furthermore, the composition is safe in operation and extremely advantageous in practice, since the toxicity of ethylene glycol monoisopropyl ether acetate used as a solvent is low. Furthermore, the ethylene glycol monoisopropyl ether acetate used in the positive-working photosensitive composition of the present invention has excellent solubility in both positive-working photosensitive compounds having quinonediazide groups and film-forming materials, and therefore has a solid content. Even if the concentration is high, viscosity does not increase easily, and it can be applied directly to substrates with steps, and even when applied to substrates with steps, there is no reduction in resolution regardless of the thickness of the coating film. can form fine patterns.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

Example 1, Comparative Example 1 2.3.4-trihydroxybenzophenone 1+*ol and 7toquinone-(14)-diazide-(2
5 g of the reaction product with 3 mol of )-5-sulfonyl chloride and phenol novolak resin 209 were dissolved and filtered through a membrane filter with a pore size of 0.45 μm to prepare a positive photosensitive composition. This product was kept at a constant temperature of 25° C., and a time-lapse test was conducted to determine whether a gel-like substance was generated. The method for confirming the gel-like substance in the aging test is as follows: 3. Using a commercially available spin coater on a 3-inch diameter silicon wafer.
This is a method of applying the above-prepared composition at a rotation speed of 0.000 rpm and observing it with a spotlight to confirm whether or not a gel-like substance is generated. Alteration and stability can be easily determined.

As a result of this aging test, no gel-like substance was observed even after 2400 hours of filtration and removal, indicating that the composition was completely stable.

On the other hand, a similar test was conducted on a composition prepared in exactly the same manner except that the conventionally used ethylene glycol monoethyl ether acetate was used instead of ethylene glycol monoisopropyl ether acetate as the solvent. A large number of gel-like substances were observed about 120 hours after filtration.

Comparative Example 2 Ethylene glycol monoethyl ether acetate) 75
9, reaction product of 2.2', 4.4'-tetrahydroxybenzophenone 1 ol and 7 toquinone-(1,2)-diazide-(1)5-sulfonic acid chloride 3 ol 59 and phenol novolak resin 209 was dissolved, filtered, and subjected to the same aging test as in Example 1.
Generation of a gel-like substance was observed after 24 hours.

Comparative Example 3 Ethoxypropyl acetate 75 was used instead of ethylene glycol monoethyl ether acetate in Comparative fF12.
A solution was prepared in the same manner as Comparative Example 2 except that g was used,
A time-lapse test was conducted; as a result, generation of a gel-like substance was observed within 24 hours.

Comparative Example 4 Ethylene glycol monoethyl ether acetate 75
In 9, 5 g of a reaction product of 2.2', 4,4'-tetrahydroxybenzophenone 1 and 4 mol of naphthoquinone-(1,2)-diazide-(2)5-sulfonyl chloride and 20 g of phenol novolak resin were dissolved. After filtration, a time-lapse test was performed, and as a result, generation of a gel-like substance was observed within 24 hours.

Example 2 A similar operation was carried out using ethylene glycol monoisopropyl ether acetate in place of ethylene glycol monoethyl ether acetate in Comparative Example 3, and as a result, no gel-like material was observed even after 170 hours.

Comparative Example 5 In cyclohexanone 759, 5 g of a reaction product of 1 liter of 2.3.4-trihydroxybenzophenone and 3 mol of naphthoquinone-(Ij) diazide-(2) 5-sulfonic acid chloride and phenol novolac resin 209 were dissolved. and passed through a membrane filter with a pore size of 0.45 μm.
A positive photosensitive composition was prepared. This product was subjected to a time-lapse test in the same manner as in Comparative Example 1, and as a result, generation of a gel-like substance was observed in 24 hours.

In addition, this composition was diluted with ethylene glycol monomethyl ether, and the change in absorbance at a wavelength of 400 am was measured with a Hitachi spectrophotometer model 323 using a quartz cell container.As a result, the change in absorbance at a wavelength of 400 am decreased over time. Decomposition of the diazide group was confirmed.

Example 3 Using ethylene glycol monoisopropyl ether acetate instead of cyclohexanone in Comparative Example 5,
As a result of measuring the change in absorbance in the same manner, no change was observed in the absorbance at a wavelength of 400 nm after about 2000 hours, thus confirming that there was almost no change in the diazide group.

Example 4 Ethylene glycol monoisopropyl ether acetate 759 with 2.3.4-trihydroxybenzophenone la+ol and naphthoquinone-(1,2)-diazide-(
2) 5 g of the reaction product with -5-sulfonyl chloride 3 ◇ 1 and m-cresol and p-cresol were mixed in a weight ratio of 40:60, formalin was added to this,
Cresol novolak resin 209 obtained by condensation using an oxalic acid catalyst by a conventional method is dissolved, and the pore size is 0.4.
A positive photosensitive composition was prepared by filtration through a membrane filter with a 5μ layer, and a time-course test for the generation of a gel-like substance was conducted in the same manner as in Example 1. No particles were observed, indicating that the composition was stable. In addition, after coating and drying this positive photosensitive composition on a silicon wafer, a resist pattern was formed on the silicon wafer by exposing it to ultraviolet light through a mask pattern and developing it. A resist pattern was obtained. The cross-sectional shape of the resist pattern is vertical, and the resolution is excellent! It was confirmed that this method can be used extremely effectively for forming fine patterns.

Comparative Example 6 As a result of carrying out the same operation using ethylene glycol mono-n-propyl ether acetate instead of ethylene glycol monoisopropyl ether acetate in Example 4, generation of a gel-like substance was observed in 120 hours.

Comparative Example 7 Ethylene glycol monoethyl ether acetate 85
9, 10 g of the reaction product of 1 mol of 2.2',4.4'-tetrahydroxybenzophenone and 3 portions of naphthoquinone-(1,2)-diazide-(15-sulfonic acid chloride) and Talesol novolac resin 309 were added. When it was dissolved and filtered and subjected to the same aging test as in Example 1, it was observed that a gel-like substance was generated after about 170 hours.

Claims (1)

[Scope of Claims] 1. A positive photosensitive composition prepared by dissolving a positive photosensitive compound having a quinonediazide group and a coating film forming material in ethylene glycol monoisopropyl ether acetate. 2. The positive-working photosensitive composition according to claim 1, wherein the total content of the positive-working photosensitive compound and the coating film-forming material is 3 to 50% by weight.