(C) a photoacid generator, and  (D) a basic compound.  Solvent  The organic solvent (A) used herein may be any organic  solvent in which the base resin, acid generator, and other  components are soluble. Illustrative, non-limiting, examples  of the organic solvent include ketones such as cyclohexanone  and methyl amyl ketone; alcohols such as 3-methoxybutanol,  3-methyl-3-methoxybutanol,  l-methoxy-2-propanol,  and  l-ethoxy-2-propanol; ethers such as  propylene glycol  monomethyl ether, ethylene glycol monomethyl ether, pro› pylene glycol monoethyl ether, ethylene glycol monoethyl  ether, propylene glycol dimethyl ether, and diethylene glycol  dimethyl ether; esters such as propylene glycol monomethyl  ether acetate (PGMEA), propylene glycol monoethyl ether  acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl  3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl  acetate, tert-butyl propionate, and propylene glycol mono› tert-butyl ether acetate; and lactones such as y-butyrolactone.  These solvents may be used alone or in combination of two or  more thereof. Of the above organic solvents, it is recom› mended to use diethylene glycol dimethyl ether, l-ethoxy-2- propanol, propylene glycol monomethyl ether acetate, and  mixtures thereof because the acid generator is most soluble  therein.  An appropriate amount of the organic solvent used is 200 to  3,000 parts, especially 400 to 2,500 parts by weight per 100  parts by weight of the base resin.  Resin  In addition to the polymer comprising recurring units hav› ing formula (1) or (2), the base resin in the resist composition  may further comprise another resin component. Specifically  the other resin component used herein includes, but is not  limited to, those polymers comprising units of the following  formula (Rl) and/or (R2) and having a weight average  molecular weight (Mw) of 1,000 to 100,000, especially 3,000  to 30,000, as measured by gel permeation chromatography  (GPC) versus polystyrene standards.  Herein,  R $^{001 }$is hydrogen, methyl or CH$_{2}$ CO$_{2}$R 003 .  R$^{002 }$is hydrogen, methyl or CO$_{2}$R 003 .  R$^{003 }$is a straight, branched or cyclic C$_{1 }$-C$_{15 }$alkyl group,  examples of which include methyl, ethyl, propyl, isopropyl,  n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl,  cyclopentyl, cyclohexyl, ethylcyclopentyl, butylcyclopentyl,  ethylcyclohexyl, butylcyclohexyl, adamantyl, ethyladaman› tyl, and butyladamantyl.  R$^{004 }$is hydrogen or a monovalent hydrocarbon group of 1  to 15 carbon atoms having at least one group selected from  among fluorinated substituent groups, carboxyl groups and  hydroxyl groups. Examples include hydrogen, carboxyethyl,  carboxybutyl, carboxycyclopentyl, carboxycyclohexyl, car› boxynorbornyl, carboxyadamantyl, hydroxyethyl, hydroxy› butyl, hydroxycyclopentyl, hydroxycyclohexyl, hydroxynor› bornyl,  hydroxyadamantyl,  [2,2,2-trifluoro-l-hydroxy-l› (trifluoromethyl)ethyl]cyclohexyl, and bis[2,2,2-trifluoro-l› hydroxy-l-(trifluoromethyl)ethyl]-cyclohexyl.  (Rl)  R)2  (OOl)c1•  H  CO2Ro14  R)2  (OOl)dl’  H  CO2Ro1s  --,----.--)al’  --,---.--)bl’  Roos  ROl3  Roo6  Roo1  ROIi  ROl2  lc2’  )d2’  k  Roo2  ROOI  H  CO2ROl4  H  CO2ROl5  100  US 8,968,979 B2  99  -continued  0  O  0  C  la3’  lc3’  H  R002  ROOI  R002  ROOI  )  <  )1  )  <  )g•  H  CO2Roo4  H  CO2Ro1s  H  ROl6  H  c-f--t  c-rt_J;•  "  (_~:t>n,,  ..  (_I)  (R $^{017}$)x•  (R $^{017}$)x•  ,t-f,,  H  H  ’X)  (R2) 