Single-alignment-level lithographic technique for achieving self-aligned

Abstract

A phase-shifting lithographic mask is made by a procedure involving only a single patterned electron, ion, or photon beam bombardment of a resist layer. The bombardment is arranged to produce three kinds of regions in the resist: no dosage, low dosage, and high dosage. These three regions in the resist are then utilized--in conjunction with an ordinary wet development step followed by either a silylation or an optical flooding technique, and thereafter by another ordinary wet development step--to pattern the resist layer and thereby to enable forming, by dry or wet etching, an underlying double layer consisting of a patterned opaque layer and a patterned transparent phase-shifting layer, the phase-shifting layer being located on, or being part of, a transparent substrate.