High density submicron features using a laser pattern generator and double patterning

Abstract

Line and space patterns have been fabricated in Si with periods as small as 1.3μm using a double patterning technique and an optical direct write tool. The pattern density of a single lithography step is shown to be limited by the proximity effect and that gratings with periods smaller than about 2.0μm are beyond the resolution of the 405nm wavelength laser direct write tool employed in these experiments. The lithography-etch–lithography-etch technique, which includes a highly selective reactive ion etch step, provides a robust way to create 4mm long gratings of 1.5μm period. Variations in this two step lithography process limit the practical minimum pitch for long gratings to about 1.4μm.