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Simulation flow and model verification for laser direct-write lithography

: Onanuga, T.; Rumler, M.; Erdmann, A.


Journal of micro/nanolithography, MEMS and MOEMS 16 (2017), Nr.3, Art. 033511, 11 S.
ISSN: 1537-1646
ISSN: 1932-5150
ISSN: 1932-5134
Fraunhofer IISB ()

A simulation flow for laser direct-write lithography (LDWL), a maskless lithography process in which a focused laser beam is scanned through a photoresist, is proposed. The simulation flow includes focusing of Gaussian beams, photoresist exposure, free-radical polymerization chemistry of the photoresist, and photoresist development. We applied the simulation method to investigate the scaling of feature sizes or linewidths for a varying number of exposure cycles at a total constant exposure dose. Experimental results from literature demonstrate that exposing the photoresist over multiple exposure cycles causes a reduction in linewidths. We explore possible reasons for this phenomenon and conclude that radical losses occurring between subsequent exposures provide a possible explanation of the observed effects. Furthermore, we apply the developed simulation method to analyze lithographic structures that were fabricated by a combination of LDWL and nano-imprint lithography. The simulation results agree with the experimental tendencies of a reduced likelihood of overexposures with an increase in the number of exposure cycles.