JPH0148532B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a positive photosensitive resin composition. More specifically, the present invention relates to a positive photosensitive resin composition made of an alkali-soluble novolak resin and having high sensitivity and suitable as a photoresist for producing integrated circuits. The mainstream of resists for producing integrated circuits is
This is a negative-tone photoresist made by adding a bisazide compound to cyclized isoprene rubber, but it has a limited resolution.As the degree of integration of integrated circuits increases year by year, this negative-tone photoresist is not suitable for future integrated circuits. We are in a situation where we are unable to adequately respond to production. On the other hand, a positive photoresist with excellent resolution can be considered to be a resist that can sufficiently cope with the miniaturization of integrated circuits. Most of the positive photoresists currently used for the fabrication of integrated circuits are novolac resins to which a 1,2-quinonediazide compound is added. Since this positive photoresist is made from a novolak resin made using a condensation polymerization method, its performance varies widely.Although its molecular weight is relatively low, its softening temperature is high, making the resist film brittle. , 2-quinonediazide compounds must be added in large amounts, so the sensitivity is lower than that of cyclized rubber-based negative photoresists. Despite these drawbacks, it is still used in the process of manufacturing integrated circuits because of its extremely high resolution. The substances that characterize positive photoresists are 1,2
-It is a quinonediazide compound. The 1,2-quinonediazide compound dissolves only in organic solvents and does not dissolve in alkaline aqueous solutions, but when exposed to ultraviolet rays as shown in the formula below, it becomes indenecarboxylic acid through ketene, and becomes extremely soluble in alkaline aqueous solutions. In other words, it critically changes from hydrophobic to hydrophilic when irradiated with ultraviolet rays, and since an alkaline aqueous solution is used as the developer, there is little change in pattern dimensions during development, and it exhibits high resolution. Furthermore, the exposure method for increasing the degree of integration of integrated circuits is about to change from the currently mainstream contact exposure method to the reduction projection exposure method. Since the reduction projection exposure method exposes the mask pattern stepwise rather than all at once, it is excellent as a means of increasing resolution, but it reduces productivity. In order to restore this productivity, it is necessary to improve the reduction projection exposure apparatus itself, but it is also important to increase the sensitivity of the positive photoresist used. As mentioned above, the currently commercially available novolak resin-based positive photoresists have low sensitivity;
There was an urgent need to improve sensitivity. As a result of intensive research into improving the sensitivity of novolak resin-based positive photoresists, the present inventors found that an alkali-soluble novolak resin and a general formula

[expression] and

[Formula] (In the formula, R ₁ and R ₃ are the same or different and are an alkyl group, a phenyl group, or an aralkyl group, and R ₂ ,
R ₄ and R ₅ are the same or different, 1,2-naphthoquinonediazide-4-sulfonyl group, 1,2-naphthoquinonediazide-5-sulfonyl group, 1,2
-benzoquinonediazide-4-sulfonyl group), and the ratio of the 1,2-quinonediazide compound is ()/()=1/9 to 9/1 (molar ratio ) It was discovered that the sensitivity of a positive photosensitive resin composition (hereinafter referred to as a photosensitive composition) characterized by the following characteristics is significantly improved, and the present invention was achieved based on this finding. The present invention will be explained in detail below. The 1,2-quinonediazide compound () or () used in the present invention includes 2,4-dihydroxyphenylmethylketone, 2,4-dihydroxyphenylethylketone, 2,4-dihydroxyphenylbutylketone, 2, 4-dihydroxyphenyl-n-hexyl ketone, 3,4-dihydroxyphenylmethyl ketone, 3,4-dihydroxyphenylethyl ketone, 3,4-dihydroxyphenylbutyl ketone, 3,4-dihydroxyphenyl-n - General formula of hexyl ketone, 2,4-dihydroxybenzophenone, 3,4-dihydroxybenzophenone, 2,4-dihydroxyphenylbenzyl ketone, 3,4-dihydroxyphenylbenzyl ketone, etc. 1,2-naphthoquinonediazide-4-sulfonyl chloride, 1,2 _- naphthoquinonediazide-4-sulfonyl chloride,
1,2-naphthoquinonediazide-5-sulfonyl chloride, 1,2-benzoquinonediazide-4-
Sulfonyl chloride and the like can be obtained by condensing 1,2-naphthoquinonediazide-5-sulfonyl chloride in the presence of an alkali catalyst. As the alkali catalyst, inorganic alkalis such as sodium hydroxide and sodium carbonate, and amines such as diethylamine and triethylamine are mainly used. 1,2-quinonediazide compounds () and ()
The usage ratio is ()/()=1/9 to 9/1 (molar ratio), preferably ()/()=2/
The molar ratio is 8 to 7/3. If the ratio of ()/() is less than 1/9, the alkali solubility of the photosensitive composition after irradiation with ultraviolet rays will be greatly reduced due to the increase in the ratio of (), and the object of the present invention will be It is not possible to obtain a photosensitive composition with high sensitivity.
Also, if the ratio of ()/() exceeds 9/1,
Since a large amount of phenolic hydroxyl groups remain in the 1,2-quinonediazide compound, the contribution of alkali insolubilization to the photosensitive composition decreases, causing the pattern to become thinner after development. The amount of these 1,2-quinonediazide compounds () and () to be used is preferably 5 to 100 parts by weight, particularly preferably 10 to 50 parts by weight, based on 100 parts by weight of the alkali-soluble novolac resin. If it is less than 5 parts by weight, it is difficult for the photosensitive composition to critically change from hydrophobic to hydrophilic by irradiation with ultraviolet rays, resulting in the disadvantage that sufficient development cannot be achieved.
Furthermore, if the amount exceeds 100 parts by weight, the added 1,2-quinonediazide compound will not be completely decomposed by short-term ultraviolet irradiation and will remain as it is, resulting in a decrease in the sensitivity of the photosensitive composition. Not improving enough. The alkali-soluble novolac resin used in the present invention preferably contains phenols and aldehydes, preferably 0.7 mol of aldehydes per mol of phenols.
It is produced by addition condensation under an acid catalyst in a proportion of ~1 mole. Phenols include phenol, o-cresol, m-cresol, p-cresol, o-
Ethylphenol, m-ethylphenol, p-
Ethylphenol, o-butylphenol, m-
Butylphenol, p-butylphenol, 2,
3-xylenol, 2,4-xylenol, 2,
5-xylenol, 2,6-xylenol, 3,
4-xylenol, 3,6-xylenol, p-
Examples include phenylphenol. These phenols can be used singly or in combination of two or more, taking into account the alkali solubility. Examples of aldehydes include formaldehyde, paraformaldehyde, and furfural. As the acid catalyst, inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid, and organic acids such as formic acid, oxalic acid, and acetic acid are used. The photosensitive composition of the present invention is prepared by dissolving the alkali-soluble novolac resin and the 1,2-quinonediazide compound () and () in a solvent. For example, the solvent may be ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc. Glycol ethers such as methyl cellosolve acetate, cellosolve esters such as ethyl cellosolve acetate, aromatic hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone and cyclohexanone, and esters such as ethyl acetate and butyl acetate. Can be done. In addition to the solubility of the constituents, these solvents
Considering the solvent evaporation rate after coating the photosensitive composition on the substrate and the effect on the surface shape of the coated film,
It is also possible to use a mixture of several types. Furthermore, if necessary, storage stabilizers, dyes, pigments, etc. may be added to this photosensitive composition. Furthermore, in order to improve the adhesion to the substrate to be coated, such as a silicon oxide film, hexamethyldisilazane, chloromethylsilane, or the like can be applied to the substrate to be coated in advance. The developing solution for the photosensitive composition of the present invention includes inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n.
- Primary amines such as propylamine, secondary amines such as diethylamine and di-n-propylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetra methyl ammonium hydroxide,
Aqueous solutions of alkalis such as quaternary ammonium salts such as tetraethylammonium hydroxide, pyrrole, piperidine, 1,8-diazabicyclo(5,4,0)-7-undecene, 1,5-diazabicyclo(4,3,0) When manufacturing integrated circuits, an aqueous solution of cyclic amines such as -5-nonane is used, and the use of metal-containing developers becomes a problem.
Preferably, aqueous solutions of quaternary ammonium salts or cyclic amines are used. Further, 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 to the aqueous solution of the alkali mentioned above can also be used as the developer. The photosensitive composition of the present invention is not only particularly useful for making integrated circuits, but also useful for making masks. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 After charging 30 g of phenol and 70 g of p-cresol into a three-neck separable flask with an internal volume of 500 ml, 66 ml of a 37% by weight formaldehyde aqueous solution and oxalic acid were added.
0.04g was added. While stirring, the separable flask was immersed in an oil bath to control the reaction temperature at 100°C, and the reaction was carried out for 10 hours to synthesize a novolak resin. After the reaction, the pressure was reduced to 30 mmHg to remove water, and the internal temperature was further raised to 130°C to remove unreacted substances. Then, the molten alkali-soluble novolak resin was returned to room temperature and recovered. Place 10 g of 2,4-dihydroxyphenylmethylketone and 1,2-naphthoquinone diazide in a three-neck separable flask with an internal volume of 500 ml under light protection.
5-sulfonyl chloride 23g, dioxane 130ml
was prepared and dissolved. 9 g of triethylamine was gradually added while stirring, and the mixture was reacted at room temperature for 2 hours.
After the reaction was completed, the contents were poured into a large amount of 1% by weight hydrochloric acid solution to recover the precipitated product. the product at 40℃,
It was heated and vacuum dried for 15 hours. When the dried product was measured using a liquid chromatogram, it was found that 2,4-dihydroxyphenylmethylketone-1,2-naphthoquinonediazide-5-sulfonic acid monoester () and 2,4-dihydroxyphenylmethylketone-1, The ratio of 2-naphthoquinone diazide-5-sulfonic acid diester () was ()/() = 4.9/5.1 (molar ratio).
(This material will be abbreviated as photosensitizer A) 20g of alkali-soluble novolak resin, photosensitizer
5 g of A was dissolved in 75 g of ethyl cellosolve acetate and filtered through a Millipore filter with a pore size of 0.2 μm to prepare a photosensitive composition solution. A solution of the photosensitive composition was applied onto a silicon oxide film wafer using a spinner, and then prebaked in an oven at 90° C. for 25 minutes to obtain a 1 μm thick photosensitive composition film. A test pattern mask manufactured by Toppan Printing Co., Ltd. was placed in close contact with the wafer, irradiated with 6 mJ/cm ² ultraviolet rays, and tetramethylammonium hydroxide 2.4
When developed with a wt% aqueous solution at 20°C for 60 seconds, a pattern with a line width of 1.0 μm could be resolved. It was found that the cumulative amount of irradiated ultraviolet light was 6 mJ/cm ² , which was a very small irradiation energy, and the photosensitive composition was that much more sensitive. Comparative Example 1 10 g of 2,4-dihydroxyphenylmethylketone and 1,2-naphthoquinone diazide were placed in a three-neck separable flask with an internal volume of 500 ml under light shielding.
5-sulfonyl chloride 35.3g, dioxane 240
ml was charged and dissolved. 15 g of triethylamine was gradually added while stirring, and the mixture was reacted at room temperature for 2 hours.
The recovered 2,4-dihydroxyphenylmethylketone-1,2-naphthoquinone diazide-5-
5 g of sulfonic acid diester (), 75 g of alkali-soluble novolak resin synthesized in Example 1
Dissolved in ethyl cellosolve acetate, pore size
A solution of the photosensitive composition was prepared by filtering through a 0.2 μm Millipore filter. When the photosensitive composition was evaluated in exactly the same manner as in Example 1, it was found that in order to resolve a pattern with a line width of 1.0 μm, the ultraviolet irradiation energy had to be 25 mJ/cm ² and the sensitivity was low. Admitted. Example 2 10 g of 3,4-dihydroxybenzophenone and 1,2-naphthoquinonediazide-5- were placed in a three-neck separable flask with an internal volume of 500 ml under light shielding.
21.3 g of sulfonyl chloride and 160 ml of dioxane were charged, thoroughly stirred and dissolved, and 9 g of triethylamine was gradually added and reacted at room temperature for 2 hours. After the reaction was completed, the contents were poured into a large amount of 1% by weight hydrochloric acid solution to recover the product. When the liquid chromatogram of the dried product was measured, it was found that 3,4-dihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid monoester () and 3,4-dihydroxybenzophenone-1, 2-
The ratio of naphthoquinone diazide-5-sulfonic acid diester () was ()/() = 3.4/6.6 (molar ratio). (This material will be abbreviated as photosensitizer B.) An alkali-soluble novolak resin was prepared in the same manner as in Example 1, except that 75 g of m-cresol and 25 g of p-cresol were used instead of 30 g of phenol and 70 g of p-cresol. did. A solution of a photosensitive composition was prepared from this alkali-soluble novolak resin and photosensitizer B in exactly the same manner as in Example 1, and the photosensitive composition was evaluated. The required ultraviolet irradiation energy was 8.9 mJ/cm ² , and the sensitivity of the photosensitive composition was extremely high. Comparative Example 2 15 g of 3,4-dihydroxybenzophenone, 4.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 200 ml of dioxane were placed in a three-necked separable flask with an internal volume of 500 ml under light shielding, and dissolved by stirring thoroughly. Then, 2 g of triethylamine was gradually added and the mixture was reacted at room temperature for 2 hours. The contents were poured into a large amount of 1% by weight hydrochloric acid/methanol mixed solvent, and the product was recovered. The liquid chromatogram of the product after drying shows 3,4-dihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid monoester () and 3,4-dihydroxybenzophenone-1,2-naphtho It was shown that the ratio of quinonediazide-5-sulfonic acid diester () was ()/() = 9.5/0.5 (molar ratio). (This material will be abbreviated as Photosensitive Agent C.) A solution of the photosensitive composition was prepared from the alkali-soluble novolac resin used in Example 2 and Photosensitive Agent C in exactly the same manner as in Example 1. When evaluated, the ultraviolet irradiation energy to reproduce a pattern with a line width of 1.0 μm was 6 mJ/cm ² .
The pattern, which should originally be 1.0 μm, became 0.6 μm, and development was observed in which the pattern became thinner.

Claims (1)

[Scope of Claims] 1. An alkali-soluble novolac resin with the general formula [Formula] and [Formula] (wherein R ₁ and R ₃ are the same or different and are an alkyl group, a phenyl group, or an aralkyl group, and R ₂ ,
R ₄ and R ₅ are the same or different, 1,2-naphthoquinonediazide-4-sulfonyl group, 1,2-naphthoquinonediazide-5-sulfonyl group, 1,2
-benzoquinonediazide-4-sulfonyl group), and the ratio of the 1,2-quinonediazide compound is ()/()=1/9 to 9/1 (molar ratio ) A positive photosensitive resin composition.