| abstract |
A sulfonium salt has formula (1) wherein R1 is a monovalent hydrocarbon group except vinyl and isopropenyl, R2, R3, and R4 are alkly, alkenyl, oxoalkyl, aryl, aralkyl or aryloxoalkyl or may bond together to form a ring with the sulfur atom, and n is 1 to 3. A chemically amplified resist composition comprising the sulfonium salt is capable of forming a fine feature pattern of good profile after development due to high resolution, improved focal latitude, and minimized line width variation and profile degradation upon prolonged PED. |