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[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. 

## Organic Solvent 

[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- 

