US Patent 11860540 Positive resist composition and patterning process

A positive resist composition comprising a base polymer comprising recurring units (a) having the structure of an ammonium salt of a sulfonamide having an iodized aromatic ring, and recurring units (b1) having an acid labile group-substituted carboxyl group and/or recurring units (b2) having an acid labile group-substituted phenolic hydroxyl group exhibits a high sensitivity, high resolution, low edge roughness and improved CDU, and forms a pattern of good profile after exposure and development.