46  US 7,232,640 Bl  45  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.  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.  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  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.  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.  Synthesis Examples 2 to 15  Synthesis of Polymers B-2 to B-15 as  Acid-Decomposable Polymers (a))  EXAMPLES  Synthesis Example 1  Synthesis of Polymer B-1 as Acid-Decomposable  Polymer (a))  Acid de› Synthesis composable  Example polymer  2  B-2  3  B-3  4  B-4  5  B-5  6  B-6  7  B-7  8  B-8  9  B-9  10  B-10  11  B-11  12  B-12  13  B-13  14  B-14  15  B-15  Compara- C-1  tive resin  Trunk Alkyl vinyl  polymer ether 1  (50 g) (amount used)  R-1  ethyl vinyl  ether (6.1 g)  R-2  ethyl vinyl  ether (6.1 g)  R-3  ethyl vinyl  ether (6.1 g)  R-1  isobutyl vinyl  ether (6.1 g)  R-2  ethyl vinyl  ether (6.1 g)  R-3  isobutyl vinyl  ether (6.1 g)  R-4  ethyl vinyl  ether (6.1 g)  R-4  isobutyl vinyl  ether (7 .1 g)  R-1  ethyl vinyl  ether (6.1 g)  R-1  methyl  isopropenyl  ether (6.3 g)  R-2  butyl  isopropenyl  ether (6.1 g)  R-4  butyl  isopropenyl  ether (6.3 g)  R-1  butyl  isopropenyl  ether 5.2 g)  R-1  phenyl  isopropenyl  ether ( 4.3 g)  R-4  ethyl vinyl  ether (8.5 g)  Alkyl vinyl  ether 2  ( amount used)  cyclohexylphenoxy- ethyl vinyl ether  (9.6 g)  t-butylcyclohexyl- carbonyloxyethyl  vinyl ether (12.1 g)  cyclohexylethyl  vinyl ether (11.3 g)  cyclohexylthioethyl  vinyl ether (13.5 g)  n-butylcyclohexyl- carbonyloxyethyl  vinyl ether (9.7 g)  phenoxyethyl vinyl  ether (7.8 g)  4-carbonylcyclo- hexylphenoxyethyl  vinyl ether (8.8 g)  benzyl vinyl ether  (9.1 g)  cyclohexylphenoxy- ethyl vinyl ether  (9.6 g)  benzyl vinyl ether  (12.0 g)  cyclohexylmethyl  vinyl ether (13.0 g)  cyclohexyl  isopropenyl ether  (10.8 g)  cyclohexylphenoxy- ethyl isopropenyl  ether (13.0 g)  phenetyl vinyl ether  (10.9 g)  TABLE 1  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 