Novel Photoacid Generators for ArF Lithography

摘要

Recently we have developed novel non-ionic photoacid generators(PAGs),2-[2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-l-(nonafluorobutylsulfonyloxyimino)-heptyl]-fluorene (DNHF)and 2-[2,2,3,3,4,4,4-heptafluoro-l-(nonafluorobutylsulfonyloxyimino)-butyl]-fluorene(HNBF),.which generate a strong acid(perfluorobutanesulfonic acid)by light irradiation and are applicable to chemically amplified ArF photoresist.The studies on quantum yield of this chemistry 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 these novel PAGs are 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 and HNBF was observed under the model immersion process while significant amount of TPSBP was eluted.Dissolution rate of the resist including DNHF exposed under the model ArF immersion condition was monitored.No clear difference against dry condition was observed.