Lithographic Evaluation of Copolymers with Enhanced Dry Etch Resistance.
CORNELL UNIV ITHACA SCHOOL OF CHEMICAL ENGINEERING
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Electron beam lithographic performance of copolymers of alpha methyl styrene with maleic anhydride PMAAMS, and with methyl maleate PMMAMS has been evaluated. RIE rates have also been determined with the purpose of developing a resist system with both adequate sensitivity and dry etch resistance. Polyalpha methyl styrene has been shown to exhibit an RIE etch rate of half that of PMMA1, but its sensitivity is poor due to its low G-scission Gs of 0.25 scissions100 ev2,3. However, the alternating copolymer of AMS with maleic anhydride PMAAMS exhibits a Gs similar to that of PMMA Gs 0.62 - 0.643,4. These findings were surprising because it had previously been expected that maleic anhydride would crosslink upon irradiation. The present work indicated negligible crosslinking. the Gs of the AMS copolymer with the monomethyl ester of maleic anhydride was previously reported as 1.63, but the present work with both gamma and electron irridation indicates higher Gs values by a factor of almost 2. Keywords Alpha methyl styrene Methyl maleate copolymer Microlithography Electron beam resist Maleic anhydride copolymer Copolymers Lithography Electron beams.
- Physical Chemistry
- Polymer Chemistry