Chemically amplified positive resist composition

A chemically amplified positive resist composition comprising

• a resin (X) which, per se, is insoluble or slightly soluble in alkali but becomes soluble in alkali when subjected to an action of acid, and has
• (a) a polymeric unit represented by the following formula (I):
• wherein R1 represents hydrogen or methyl, R2 and R3 each independently represent alkyl having 1 to 4 carbon atoms, and R4 and R5 each independently represent hydrogen, hydroxyl or alkyl, wherein the adamantly ring bonds to the carbon linking R2 and R3 at either the 1-position or the 2-position,
• (b) polymeric unit, derived from an alicyclic olefin, represented by the following formula (II):
• wherein R6 and R7 each independently represent hydrogen, alkyl having 1 to 3 carbon atoms, hydroxyalkyl having 1 to 3 carbon atoms, carboxyl, cyano or a group represented by —COOR8, wherein R8 represents an alcohol residue,
• or R6and R7 together form a carboxylic acid anhydride residue represented by —C(═O)OC(═O)—, and
• (c) a polymeric unit derived from unsaturated dicarboxylic acid anhydride selected from maleic anhydride and itaconic anhydride;
• and
• an acid generating agent (Y).