A resist composition comprising a base polymer and a sulfonium salt of amino-containing carboxylic acid offers dimensional stability on PPD and a satisfactory resolution.

A negative resist composition comprising (A) a sulfonium compound of betaine type and (B) a polymer is provided. The resist composition is effective for controlling acid diffusion during the exposure step, exhibits a very high resolution during pattern formation, and forms a pattern with minimal LER.

A negative resist composition comprising (A) a sulfonium compound of betaine type and (B) a polymer is provided. The resist composition is effective for controlling acid diffusion during the exposure step, exhibits a very high resolution during pattern formation, and forms a pattern with minimal LER.

A resist composition comprising a base polymer and a sulfonium or iodonium salt of iodinated phenoxy or iodinated phenylalkoxy-containing fluorinated sulfonic acid offers a high sensitivity and minimal LWR or improved CDU independent of whether it is of positive or negative tone.

A resist composition comprising a base polymer and a sulfonium or iodonium salt of iodinated phenoxy or iodinated phenylalkoxy-containing fluorinated sulfonic acid offers a high sensitivity and minimal LWR or improved CDU independent of whether it is of positive or negative tone.

A resist composition comprising a 2,5,8,9-teraaza-1-phosphabicyclo[3.3.3]undocane, biguanide or phosphazene salt of an iodinated aromatic group-containing carboxylic acid exhibits a sensitizing effect and an acid diffusion suppressing effect and forms a pattern having improved resolution, LWR and CDU.

A resist composition comprising a 2,5,8,9-teraaza-1-phosphabicyclo[3.3.3]undocane, biguanide or phosphazene salt of an iodinated aromatic group-containing carboxylic acid exhibits a sensitizing effect and an acid diffusion suppressing effect and forms a pattern having improved resolution, LWR and CDU.

There is provided a resin composition including a copolymer having structural units of Formula (1), Formula (2), and Formula (3), and a solvent; or a resin composition including a copolymer having structural units of Formula (1), Formula (4), and Formula (5), and a solvent. ##STR00001##

A novel process for preparing vinyl aromatic polymer particles is described. The particles and beads are suitable for being processed into foamed styrenic products of substantially improved insulation values, as well as other useful products.

A novel process for preparing vinyl aromatic polymer particles is described. The particles and beads are suitable for being processed into foamed styrenic products of substantially improved insulation values, as well as other useful products.