Performance of imide and methide onium PAGs in 193nm resist formulations

The performance of a new class of photoacid generators (PAGs) made from the onium salts of bis(perfluoroalkylsulfonyl)imide and tris(perfluoroalkylsulfonyl)methide anions were studied in 193nm formulations. The lithographic properties such as sensitivity, resolution, pattern profiles, footing, I-D bias and PEB sensitivity were investigated in methacrylate and COMA/methacrylate hybrid type matrix resins. In general the iodonium PAGs were about three times slower than the sulfonium PAGs. Methide and imide PAGs possessing similar fluoroalkylgroups showed comparable performance in terms of exposure latitude, I-D bias. And PEB sensitivity. Compared to the reference PAG, the profiles exhibited T-tops and scum. Among the new PAGs studied bis(perfluorobutanesulfonyl)imide exhibited close performance to that of the reference PAG except for the scum. Details on the exposure results of these PAGs in both methacrylate type and COMA/methacrylate hybrid type polymer based 193nm resist formulations are provided.