Recent Progress in Excimer Laser Lithography

Abstract

ABSTRACTA KrF excimer laser exposure method has been developed for laboratory use, which employs 10 to 1 achromatic projection lens of 0.37 NA and 5x5 mm field size , and a TTL alignment system using the double diffraction method, which was realized by the use,of the achromatic lens. Novolak type mid-UV resists, such as AZ-5214 and PR-1024, were best suited for use in 248 nm exposure, considering the sensitivity and etching resistance from a practical viewpoint, and an additional post exposure baking process also improved the resist profile. The dependences of the exposure characteristics on the energy density per pulse and pulse frequency of these resists were not observed in the region of the practical exposure conditions. An alignment precision of x±30-= 0.2 μm was achieved for the alignment mark consisting of poly Si pattern. Thus, a 0.3 μm line and space pattern was realized by using tri-level resist process and a 0.2 μm gate pattern was successfully fabricated on the coplanar pattern with a 0.4 μm step.