Tobias Hintermann

Evaluation of a novel photoacid generator for chemically amplified photoresist with ArF exposure

Recently we have developed a novel non-ionic photoacid generator (PAG), 2-[2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1-(nonafluorobutylsulfonyloxyimino)-heptyl]-fluorene (DNHF), which generates a strong acid (perfluorobutanesulfonic acid) by light irradiation and is applicable to chemically amplified ArF photoresist. The studies on quantum yield of the PAG under 193 nm exposure in an ArF model formulation and in a solution comparing with the ones of ionic PAGs, triphenylsulfonium perfluorobutanesulfonate (TPSPB) and Bis(4-tert-butylphenyl)iodonium perfluorobutanesulfonate (BPIPB) revealed that this compound is superior in photo efficiency to the others. PAG leaching into water from the resist during a model immersion process was investigated in detail. No leaching of DNHF was observed under the immersion process while significant amount of TPSBP was eluted. Dissolution rate of the resist prepared under a model condition of ArF immersion exposure was monitored. No clear difference against dry condition was observed.

Novel nonionic photoacid generator releasing strong acid for chemically amplified resists

Recently we have developed a novel non-ionic PAG, which generates a strong acid (perfluorobutanesulfonic acid) by light irradiation, and is applicable for chemically amplified photoresists. Application-relevant properties such as solubility in common organic solvents and water, thermal stability, storage stability in neat form and solution, UV absorption, and sensitivity in model formulations were evaluated. The compound showed good solubility in organic solvents and no solubility in water. Good storage stability was observed in solution, even in the presence of amine, where conventional non-ionic PAGs were not found to be stable. From the evaluation in the model formulation with ArF laser exposure, it was found that this new compound has high transparency at 193 nm and superior photo-efficiency to triphenylsulfonium perfluorobutanesulfonate (TPSPB). In addition, the new compound exhibited significant sensitivities at DUV (254 nm) and i-line (365 nm) wavelengths.