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polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate ). 

The amount of these surfactants mixed is generally at most 2% by weight, preferably at most 1 % by weight, based on the total solids in the present composition. 

These surfactants may be added alone, or some of them can be added as combinations. 

The electron-beam, X-ray or EUV positive resist compo› sition relating to the invention is coated on a substrate for production of precision integrated circuit elements ( e.g., silicon/silicon dioxide coating) in accordance with an appro› priate coating method, e.g., a method of using a spinner or a coater. After coating, the resist-composition is pre-baked, exposed to light via the desired mask, post-baked, and then developed. Thus, resist patterns of good quality can be obtained. 

As the exposure light source used herein, far ultraviolet rays having wavelengths of 250 nm or below are suitable. Examples of exposure light usable herein include KrF excimer laser (248 nm), ArF excimer laser (193 nm), F$_{2 }$ excimer laser (157 nm), EUV (13 nm), X-rays and electron beams. 

Examples of an alkali developer usable for the present electron-beam, X-ray or EUV positive resist composition include aqueous alkaline solutions containing 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-butylamine), tertiary amines (such as triethylamine and methyldiethylamine), alcoholamines (such as dimethyl› ethanolamine and triethanolamine ), quaternary ammonium salts (such as tetramethylammonium hydroxide and tetra› ethylammonium hydroxide), or cyclic amines (such as pyr- role and piperidine ). 

The aqueous alkaline solutions to which alcohol and surfactants are further added in appropriate amounts can also be used. 

The invention will now be illustrated in greater detail by reference to the following examples, but these examples should not be construed as limiting the scope of the inven› tion. 

## Synthesis of Polymer B-1 as Acid-Decomposable Polymer (a)) 

Poly(p-hydroxystyrene) produced by Nippon Soda Co., Ltd. (Resin R-1) (molecular weight: 8,000, dispersion degree: 1.05) in an amount of 50 g was dissolved in 240 g of propylene glycol monomethyl ether acetate (PGMEA) This solution was heated at 60° C. and evacuated till the pressure in the reaction vessel was reduced to 20 mmHg. Thus, about 40 g of the solvent was distilled away together with the water remaining in the system. 

The resulting solution was cooled to 20° C., and then admixed with 6.1 g of ethyl vinyl ether, 4.0 g of cyclohexy› lphenoxyethyl vinyl ether synthesized separately, and 0.02 g of paratoluenesulfonic acid, followed by stirring for one 65 hour at room temperature. Thereafter, 0.02 g of triethy› lamine was further added for neutralization, and extraction 

## EXAMPLES 

## Synthesis Example 1 

operation using 240 g of ethyl acetate and 140 g of water was performed three times. The thus obtained polymer was referred to as B-1. 

Acid-decomposable polymers were synthesized in the same manner as in Synthesis Example 1, except that the polymer having phenolic hydroxyl groups (trunk polymer) and the two kinds of alkyl vinyl ethers were replaced by those shown in Table 1, respectively, and referred to as Polymers B-2 to B-10, respectively. 

In addition, a comparative resin (C-1) was synthesized in the same manner as described above, except that only one kind of alkyl vinyl ether shown in Table was used for acetalation. 

<img src='content_image/884964.jpg'>

R-1: poly(p-hydroxystyrene), molecular weight: 8,000, dis› persion degree: 1.05 

R-2: p-hydroxystyrene/p-acetoxystyrene (85/15) copolymer resin, molecular weight: 9,000, dispersion degree: 1.4 

R-3: p-hydroxystyrene/t-butylacrylate (85/15) copolymer resin molecular weight: 10,000, dispersion degree: 1.5 

R-4: p-hydroxystyrene/styrene (95/5) copolymer resin, molecular weight: 10,000, dispersion degree: 1.5 

## Synthesis Examples 2 to 15 

## Synthesis of Polymers B-2 to B-15 as Acid-Decomposable Polymers (a)) 

