Ion beam proximity lithography on spherical substrates with continuously scanned, self-complementary masks

Abstract

This article demonstrates, for the first time, the formation of 1 μm Manhattan geometries on a 3 mm deep spherical substrate subtending a 60° angle. The approach uses ion beam proximity lithography to achieve the large depth-of-field and a self-complementary mask strategy to enable each wafer level to be defined by a single, dimensionally stable mask. This demonstration is a first step toward validating a more general approach that modeling suggests will be capable of patterning 7.5 mm deep substrates with twice the subtended angle.