74  US 10,005,868 B2  73  -continued  This polymer compound was named Comparative poly› mer 2.  Comparative Synthesis Example 1  Comparative polymer 1 was synthesized in the same  manner as in Synthesis Example 2.  Copolymerization Composition Ratio (Mole Ratio)  methacrylic  acid 3-isopropyl-3-cyclopentyl  ester:meth- acrylic acid 3-hydroxy-1-adamantyl ester:methacrylic acid  2-oxooxolan-3-yl ester=0.50:0.10:0.40  Weight average molecular weight (Mw)=9,300  Molecular weight distribution (Mw/Mn)=l.82  This polymer compound was named Comparative poly› mer  1.  Examples 1 to 6 and Comparative Examples 1 and  2  Preparation of Resist Composition  The polymer compounds (Polymers 1 to 6 and Compara› tive polymers 1 and 2) thus synthesized were each dissolved  in a solvent containing 100 ppm of a surfactant, FC-4430  available from Sumitomo 3M, Ltd., with the composition  shown in Table 1 to form solutions. The solutions were  filtered through a 0.2-µm  filter to prepare resist compositions  (Examples 1 to 6 and Comparative Examples 1 and 2).  Polymers 1 to  6:  compounds obtained in Synthesis  Examples 2-1 to 2-6  Comparative polymers 1 and 2: compounds obtained in  Comparative Synthesis Examples 1 and 2  Organic solvent: PGMEA (propylene glycol monomethyl  ether acetate)  CyH (cyclohexane)  GBL (y-butyrolactone)  Acid generator: PAG 1, PAG 2 (shown by the following  structural formulae)  The components shown in Table 1 are as follows.  Comparative polymer 2 was synthesized in the same  manner as in Synthesis Example 2.  Copolymerization Composition Ratio (Mole Ratio)  methacrylic acid l-(adamantan-l-yl)-1-methylethyl ester:4- tert-amy loxystyrene:methacry lie  acid  4-hydroxypheny 1  ester:methacrylic acid 3-oxo-2, 7-dioxatricyclo[ 4.2.1.0 4 • 8 ]  nonan-9-yl ester:PAG monomer 2=0.20:0.20:0.20:0.25:0.15  Weight average molecular weight (Mw)=7,700  Molecular weight distribution (Mw/Mn)=l.89  Comparative Synthesis Example 2  0  0  F2  0  C  y  ’-s03- 0  cc\)  s+  Comparative polymer 1  ,r~  ~  ~  ~~::- .A~  .A~  0  0  0  0  0  0  rb  ~OH  &O  Comparative polymer 2  r  0  0 