Dec. 17, 2020  113  US 2020/0393760 Al  [0148]  In the positive resist composition, the acid genera› tor of addition type is preferably used in an amount of 0.1  to 50 parts, more preferably 1 to 40 parts by weight per 100  parts by weight of the base polymer. When the base polymer  contains recurring units (dl) to (d3) and/or the acid genera› tor of addition type is added, the positive resist composition  functions as a chemically amplified positive resist compo› sition.  [0149]  The positive resist compos1t10n may contain an  organic solvent. The organic solvent is not particularly  limited as long as the foregoing components and other  components are dissolvable therein. Examples of the organic  solvent used herein are described in U.S. Pat. No. 7,537,880  (JP-A 2008-111103, paragraphs [0144]-[0145]). Exemplary  solvents include ketones such as cyclohexanone, cyclopen› tanone, methyl-2-n-pentyl ketone, and 2-heptanone; alco› hols such as 3-methoxybutanol, 3-methyl-3-methoxybuta› nol,  l-methoxy-2-propanol,  l-ethoxy-2-propanol,  and  diacetone alcohol (DAA); ethers such as propylene glycol  monomethyl ether, ethylene glycol monomethyl ether, pro- Organic Solvent  -continued  j  0  ___r-{O_z_~F3  0---r- ’ ~S03- 0  -continued  x"-Q-o  XBI  0 