JPH03618B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positive-working photosensitive coating composition having excellent storage stability and fine pattern forming properties.

Generally, the formation of fine patterns using photoresists involves applying a solution containing a photosensitive material onto a substrate, such as by roll coating, flow coating, spin coating, dip coating, spray coating, or doctor coating. After applying the photosensitive layer by vaporizing the solvent and irradiating it with active light through a desired mask pattern, taking advantage of the difference in resistance between the irradiated and non-irradiated areas, This is done by selectively removing either the irradiated area or the non-irradiated area. In this case, those in which only the irradiated areas are selectively removed are classified as positive types, and on the contrary, those in which non-irradiated areas are selectively removed are classified as negative types.
Regarding the former positive type, this invention particularly relates to improving the storage stability of a coating solution containing a photosensitive material suitable for wet development using a developer.

The positive-working photosensitive material-containing coating solution of the present invention is a solution composed of a photosensitive compound, a coating film-forming material, and a solvent for dissolving these, and the photosensitive compound that provides positive photosensitivity includes: Examples include quinonediazide group-containing compounds having orthobenzoquinonediazide, orthonaphthoquinonediazide, orthoanthraquinonediazide groups, and the like. These quinonediazide compounds are easily photodecomposed by irradiation with actinic light to produce carboxylic acid, which changes into a substance soluble in alkaline liquid.Using this property, we can develop photosensitive compounds for positive working. It is suitably used as However, these groups have extremely poor stability, so in order to stabilize them, the phenolic hydroxyl group is esterified, such as naphthoquinone-(1,2)-diazide-(2)-5-sulfonate. Measures such as digitization are being adopted. However, stabilizing photosensitive compounds in this manner is not only industrially disadvantageous, but also inevitably results in the loss of desirable properties of the photosensitive compounds.

On the other hand, when a coating solution is prepared by dissolving the above-mentioned positive photosensitive compound in a solvent, the solution may decompose during storage, resulting in a decrease in photosensitivity, or the dissolved photosensitive compound may deteriorate over time. It had the disadvantage that it recrystallized and precipitated, impairing the uniformity of the solution. One important factor in the stability of a solution is the interaction between the solute and the solvent, 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. In the case of a coating solution containing a positive photosensitive material, it has a strong dissolving power for both the photosensitive compound and the coating film forming material, and forms a uniform solution regardless of its concentration, resulting in a uniform and smooth coating. It is important to be able to provide a coating film, and a suitable solvent is selected depending on the type of each solute. It is known that a very wide range of organic solvents can be used as a solvent for a coating solution containing a positive photosensitive material, but cyclohexanone and ethylene glycol monoethyl ether acetate are practically used as preferred solvents. however,
In a coating solution using cyclohexanone as a solvent, the photosensitive compound gradually decomposes during storage, resulting in a decrease in photosensitivity; However, the drawback of recrystallization of the chemical compound could not be overcome, and none of them could be said to be fully satisfactory. Therefore, there has been a strong demand in this technical field for a stable positive-working photosensitive material-containing solution that does not reduce photosensitivity even after long-term storage and can form a uniform and smooth coating film.

The inventors of the present invention have conducted extensive research with the aim of solving the above-mentioned drawbacks of conventional coating solutions for positive photosensitive coatings and providing an extremely stable coating solution, and as a result, they have developed cyclopentanone. The inventors have discovered that the object can be achieved by using it as a solvent, leading to the present invention.

That is, the present invention provides a composition for forming a positive photosensitive coating film, which is prepared by dissolving a positive photosensitive compound having a quinonediazide group and a coating film forming material in cyclopentanone.

Examples of the positive photosensitive compound containing a quinonediazide group used in the composition of the present invention include orthobenzoquinonediazide, orthonaphthoquinonediazide, orthoanthraquinonediazide, and compounds containing an azide group, such as orthonaphthoquinonediazide sulfonic acid ester. Nuclear-substituted derivatives can be mentioned, and compounds having orthoquinone diazide sulfonyl chloride and a hydroxyl group or an amino group, such as phenol, p-methoxyphenol, dimethylphenol, hydroquinone, bisphenol A, naphthol, pyrocatechol, pyrogallol, pyrogallol monomethyl Also included are reaction products with ether, pyrogallol-1,3-dimethyl ether, gallic acid, esterified or etherified gallic acid with some hydroxyl groups left, aniline, p-aminodiphenylamine, phenolic resin, etc. Ru. These photosensitive compounds are usually used alone, but two or more types can also be used in combination.

Furthermore, as the coating film-forming material used in the composition of the present invention, alkali-soluble resins are preferable, such as novolac resins produced by condensing phenol or cresol with aldehydes, polyvinyl alcohol, polyvinyl alkyl ether, etc. , copolymer of styrene and acrylic acid,
Examples include copolymers of methacrylic acid and methacrylic acid alkyl esters, hydroxystyrene polymers, polyvinylhydroxybenzoate, and polyvinylhydroxybenzal.
These can also be used alone or in combination of two or more.

The ratio of the photosensitive compound to the coating film forming material used is usually in the range of 1:2 to 1:10 by weight. In this case, if the positive photosensitive compound contains a coating film forming component such as a phenol resin, the coating film forming component in the positive photosensitive compound is regarded as the coating film forming material and the conversion is performed. good. Too much coating film-forming material is undesirable because it will cause deterioration of the fidelity of the mask pattern of the resulting image and a reduction in transferability, while too little amount will cause a decrease in the strength and uniformity of the formed coating film and a decrease in resolution. This is not preferable as it causes deterioration. Generally, the preferred ratio of photosensitive compound to film-forming material is in the range of 1:2.5 to 1:5.5 by weight.

The solvent used in the present invention has never been used as a solvent for a solution for forming a positive photosensitive coating film. The amount used is not particularly limited as long as it can provide a positive photosensitive coating forming solution that forms a uniform thin layer when applied to the coated substrate, but usually the solid content, that is, the positive photosensitive Amounts are used to provide a solution composition with a concentration of compound and film-forming material ranging from 3 to 50% by weight.

The solution 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 known in the art. Various commonly used additives can be included.

When high resolution is required, such as when using photoresist for manufacturing hard masks, it is preferable to set the photoresist film thickness to about 0.2 μm.
If the composition of the present invention is used, the solid content concentration can be reduced to 3 to 5.
Spin coating may be performed at a rotation speed of 3000 rpm in terms of weight %. Furthermore, when it is necessary to coat a substrate with large differences in level, the conventional method uses a so-called multilayer resist method, in which the recesses are filled and then a photoresist is applied, but if the composition of the present invention is used, 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 coating is possible, and it can be applied directly to substrates with steps without filling in the recesses in advance. It is possible to obtain a film as thick as 3 μm just by coating it, and it is possible to form fine patterns with high resolution on a substrate with steps.

To give one example of a preferred method of using the composition of the present invention, first, a quinonediazide group-containing photosensitive compound and a coating film-forming material are dissolved in cyclopentanone on a support such as a silicon wafer. The positive-working photosensitive coating film-forming composition prepared above is applied using a spin coater or the like, and the solvent is removed to form a dry photosensitive layer. Next, a light source that emits ultraviolet light, such as a low-pressure mercury lamp, a high-pressure mercury lamp,
Using an ultra-high pressure mercury lamp, an arc lamp, a xenon lamp, etc., exposure is performed through a required master pattern, or irradiation is performed while scanning an electron beam. Next, when this is immersed in a developer, for example a weakly alkaline aqueous solution such as a 1-2% aqueous sodium hydroxide solution,
The portions made solubilized by exposure are selectively dissolved and removed, resulting in a positive image faithful to the mask pattern.

The positive photosensitive coating film forming solution composition of the present invention has significantly superior stability compared to conventional compositions,
Moreover, cyclopentanone has an extremely weak decomposition effect or decomposition promoting power on diazide groups, so
The photosensitive properties of the quinonediazide group-containing compound do not deteriorate, and it is possible to provide a positive photosensitive coating film with higher resolution even after long-term storage than conventional ones.
Furthermore, since the composition of the present invention has a very high evaporation rate of the solvent cyclopentanone, it can be spun onto a substrate.
It can be applied with a low-concentration composition with a viscosity about 1/3 of that of conventional products when turned on and rotated to obtain a coating film.
Therefore, the amount of the composition consumed when forming on a similar substrate is approximately half that of the conventional method. Furthermore, when coating onto a substrate with steps, the composition of the present invention has a higher volatilization rate of cyclopentanone and dries faster during coating than conventional compositions that have had problems covering the step portion. Therefore, it has the advantage that a film with good coverage can be obtained.

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 and Comparative Example 1 75 g of cyclopentanone, 1 mol of 2,3,4-trihydroxybenzophenone and naphthoquinone
5 g of the reaction product with 3 mol of (1,2)-diazide-(2)-5-sulfonyl chloride and 20 g of phenol novolac resin were dissolved, filtered through a 0.45 μm membrane filter, and a positive photosensitive coating solution was prepared. was prepared. This product was kept at a constant temperature of 25°C, and a time-lapse test was conducted to determine the generation of gel-like substances. The method for confirming gel-like substances in the aging test is to coat a 3-inch diameter silicon substrate with a commercially available spin coater at 3000 rpm.
This method involves applying the filtered coating solution at a rotational speed of and stability can be easily judged.

As a result of this time-lapse test, no gel-like substance was observed even after 2400 hours had passed after filtration, and it was confirmed that the coating liquid was completely stable.

On the other hand, as a result of conducting the same test on a coating solution prepared in exactly the same manner except that the conventionally used ethylene glycol monoethyl ether acetate was used instead of cyclopentanone as a solvent, it was found that after filtration, this solution was approximately Many gel-like substances were observed after 120 hours.

Comparative Example 2 75 g of ethylene glycol monoethyl ether acetate, 1 mol of 2,2',4,4'-tetrahydroxybenzophenone and naphthoquinone-(1,2)-
Diazide-(2)-5-sulfonic acid chloride 3 mol
5 g of the reaction product with and 20 g of phenol novolac resin
When the above-mentioned time-lapse test was performed after dissolving and filtering g, it was observed that a gel-like substance was generated in 24 hours.

Example 2 75g of cyclopentanone instead of ethylene glycol monoethyl ether acetate in Comparative Example 2
A solution was prepared in the same manner as in Comparative Example 2, except for using
It was not recognized until 1200 hours.

Comparative Example 3 75 g of ethylene glycol monoethyl ether acetate, 1 mol of 2,2',4,4'-tetrahydroxybenzophenone and naphthoquinone-(1,2)-
5 g of reaction product with 4 mol of diazide-(2)-5-sulfonyl chloride and 20 g of phenol novolak resin
After dissolving and filtering, a time-lapse test was performed, and as a result, a gel-like substance was observed to form within 24 hours.

Example 3 A similar operation was carried out using cyclopentanone in place of ethylene glycol monoethyl ether acetate in Comparative Example 3, and as a result, no gel-like substance was observed up to 170 hours.

Comparative Example 4 75 g of cyclohexanone, 1 mol of 2,3,4-trihydroxybenzophenone and naphthoquinone
5 g of the reaction product with 3 mol of (1,2)-diazide-(2)-5-sulfonic acid chloride and 20 g of phenol novolac resin were dissolved and passed through a 0.45 μm membrane filter to prepare a positive photosensitive coating solution. This product was subjected to a time test in the same manner as in Comparative Example 1, and as a result, no gel-like substance was observed up to 2400 hours.

In addition, this coating solution was diluted with methyl cellosolve, and using a quartz cell container, a Hitachi spectrophotometer 323 was used.
As a result of measuring the change in absorbance at a wavelength of 400 nm with the mold, it became smaller over time, confirming the decomposition of the diazide group.

Example 4 As a result of measuring the change in absorbance in the same manner using cyclopentanone instead of cyclohexanone in Comparative Example 4, no change in absorbance at a wavelength of 400 nm was observed after about 2000 hours, and therefore, it was found that the change in absorbance at a wavelength of 400 nm was not observed after about 2000 hours. It was found that there were almost no changes.

Comparative Example 5 75 g of ethylene glycol monoethyl ether acetate, 5 g of a reaction product of 1 mol of 2,3,4-trihydroxybenzophenone and 2 mol of naphthoquinone-(1,2)-diazide-2-(5)-sulfonic acid chloride, and A positive photosensitive coating solution was prepared by dissolving 20 g of phenol novolac resin and filtering it through a 0.45 μm membrane filter. This material was coated using a spin coater on a silicon wafer with a SiO ₂ layer consisting of a line and space pattern approximately 20,000 Å thick on the surface.
The coating was applied at a rotation speed of 3000 rpm, dried for 30 minutes in a thermal circulation dryer at 85°C, and the SEM cross-sectional photographs were observed. As a result, there was a large difference in the film thickness between the SiO ₂ top surface and the Si surface, and the film thickness at the step area was large. It was thin and had poor coverage.

Example 5 75 g of cyclopentanone was used instead of ethylene glycol monoethyl ether acetate in Comparative Example 5.
When similar operations were carried out using , it was confirmed that there was little difference in film thickness between the SiO ₂ surface and the Si surface, and that the covering of the step area was good.

Claims (1)

[Scope of Claims] 1. A composition for forming a positive photosensitive coating film, which is obtained by dissolving a positive photosensitive compound having a quinonediazide group and a coating film forming material in cyclopentanone. 2. The total concentration of the positive photosensitive compound and coating film forming material dissolved in cyclopentanone is 3 to 50% by weight.
The composition according to claim 1.