Chemically Amplified Resists: A Lithographic Comparison of Acid Generating Species.
01 January 1989
Deep-UV (240-250 nm) lithography is of one the most promising new lithographic techniques for patterning devices with 0.35- 0.5microns structures. Chemically amplified resists have been reported to meet the necessary requirements of both excimer laser and Hg source-based exposure tools. The chemistry of one family of these materials involves the photogeneration of organic acid catalysts from 2,6-dinitrobenzyl esters, which, upon mild heating, effect the removal of a t-butoxy (t-BOC) protecting group from poly(t-butoxycarbonyloxy-alpha- methylstyrene), [poly(t-BOC-alpha-methylstyrene)]. The thermal behavior of the esters has been examined, and the quantum yield determined for selected examples. A lithographic evaluation of resists based upon several organic ester acid precursors and poly (t-BOC-alpha-methylstyrene) has been made. Sensitivities ranging from 2 to 100 mJ/cm sup 2 in the deep-UV region have been observed, and 0.5microns resolution has been demonstrated, using a contact printer equipped with a 248 nm laser source.