42  US 8,906,600 B2  41  !ethyl vinyl ether as a vinyl ether compound and 1 .45 g of 2  mass % comphorsulfonic acid (PGMEA solution) were  added thereto, and the mixture was stirred at room tempera› ture for 2 hours. Furthermore, 1.05 g of 10 mass% triethy› lamine (PGMEA solution) was added and after stirring for a  while, the reaction solution was transferred to a separating  funnel containing 165 mL of ethyl acetate. The organic layer  was washed with 200 mL of distilled water three times, and  ethyl acetate was removed in an evaporator. The obtained  reaction solution was added dropwise to 2 L of hexane, and  the supernatant was removed. The obtained product was dis› solved in 95 g of PGMEA, and the low-boiling-point solvent  was removed under reduced pressure conditions to obtain  132.3 g of a PGMEA solution (28.3 mass %) of Polymer  Compound (R-11 ).  and the solvent not having a hydroxyl group is usually from  1/99 to 99/1, preferably from 10/90 to 90/10, more preferably  from 20/80 to 60/40.  The solvent having a hydroxyl group is preferably an alky› lene glycol monoalkyl ether, and the solvent not having a  hydroxyl group is preferably an alkylene glycol monoalkyl  ether carboxylate.  The amount used of the solvent based on the entire amount  of the composition of the present invention may be appropri› ately adjusted according to the desired film thickness or the  like, but in general, the amount used is adjusted such that the  entire solid content concentration of the composition  becomes from 0.5 to 5 mass%, preferably from 0.8 to 3 mass  %, more preferably from 0.8 to 2 mass %, still more prefer› ably from 0.8 to 1.5 mass %.  [ 6] Other Additives  Other than the above-described components, the composi› tion of the invention may appropriately contain an onium  carboxylate, a dissolution inhibiting compound having a  molecular weight of3,000 or less described, for example, in  Proceeding ofSPIE, 2724, 355 (1996), a dye, a plasticizer, a  photosensitizer, a light absorber, an antioxidant and the like.  Also, in the case of using EUV as the exposure light source,  the composition may contain an additive capable of absorbing  out-of-band light. Examples of the out-of-band light absorber  include the aromatic compounds described in U.S. Patent  Application Publication No. 2006/0223000.  With respect to Polymer Compound (R-11 ), the molar ratio  of respective repeating units was determined using $^{1 }$H-NMR  and  $^{13}$C-NMR. Also, the mass average molecular weight  (Mw) in terms of polystyrene and the polydispersity (Mw/  Mn) were determined using GPC (solvent: THF). The results  are shown in Table 1 below  In Table 1, the molar ratio of respective repeating units  (corresponding to repeating units starting from the left) is  shown in the column of"Compositional Ratio", and the mass  average molecular weight in terms of polystyrene as mea› sured using GPC (solvent: THF) is shown in the colunm of  "Mw". Also, the polydispersity Mw/Mn is shown in the col- unm of"Polydispersity".  The present invention is described below by referring to  Examples, but the present invention should not be construed  as being limited thereto.  In Table 1, Polymer Compounds (R-8), (R-10) and (R-17)  were synthesized by the same method as in the synthesis  example of Polymer Compound (R-11) except for differing in  the acetalizing agent.  Polymer Compound (R-12) was synthesized by obtaining a  precursor of Polymer Compound (R-12) by a known radical  polymerization method using p-acetoxystyrene and cyclo› hexyl acrylate and thereafter, introducing an acetal protective  group by the same operation as in Polymer Compound (R-11)  except for differing in the acetalizing agent.  Polymer-XI was synthesized by a known radical polymer› ization method using p-acetoxystyrene and tert-butyl meth› acrylate.  Poly(p-hydroxystyrene) (VP-2500, produced by Nippon  Soda Co., Ltd.) (30 g) as a polyhydroxystyrene compound  was dissolved in 120 g of PGMEA (propylene glycol monom› ethyl ether acetate). To this solution, 10.40 g of2-cyclohexy- EXAMPLES  Synthesis Example 1  Synthesis of Polymer Compound (R-11)  Polymer Compound (A)  OH  R-8  Mass Average  Molecular  Weight(Mw)  5500  Compositional  Polydispersity Ratio (molar ratio,  (Mw/Mn)  from left)  1.1  10/70/20  TABLE 1 