| abstract |
In photolithography using a high energy beam such as ArF excimer laser light, EB, EUV or the like as a light source, acid diffusion is small, sensitivity and MEF balance are excellent, rectangularity is excellent, and compatibility is excellent. Provided is a photoacid generator or the like used for a chemically amplified resist composition in which defects are hardly exhibited. An onium salt represented by the following formula (1). [Selection figure] None |