The present invention relates to the field of
material technology, and more specifically, to an
onium salt compound, a
photoacid generator, a
photoresist composition, and a pattern forming method. The
onium salt compound is a salt composed of anions and cations, wherein the cations are
sulfonium cations or iodonium cations; the anion general formula is as shown in formula (B): In formula (B), R1 is an ester-containing group that can react with TMAH developer, R2 is a substituted or unsubstituted
cycloalkane group with a
carbon number of 6 to 10, and n is any integer between 1 and 3. ‑ The combination of
fluorine atoms with
high electron-withdrawing properties at relatively close positions can enhance the acidity, while introducing a
cyclic hydrocarbon group with large spatial volume to reduce the
diffusion of the acid; in addition, the addition of a group fragment with an ester group that can be cleaved by an alkaline developer can effectively reduce the development defects. The
onium salt compound provided by the present invention is used as a
photoacid generator to meet the current demand for high-resolution
resist patterns, including low
line width roughness (LWR) of the pattern and a smaller
mask error enhancement factor (MEEF) of the line pattern, as well as fewer development defects.