Hard mask process to prevent surface roughness for selective dielectric etching

Abstract

The propagation of microfissures from a photoresist to an underlying material layer during lithography and etching can be substantially prevented by placing a hard mask between the photoresist and the material layer to be etched. Specifically, the microfissure propagation is substantially prevented by (a) forming a compressive hard mask on a surface of a non-compressive material layer that is to be patterned by lithography and etching; (b) forming a patterned photoresist on said hard mask, wherein a portion of said hard mask is exposed; (c) removing said exposed portion of said hard mask so as to expose a portion of said non-compressive material layer; and (d) transferring said pattern from said patterned photoresist to said exposed portion of said material layer by etching, wherein said hard mask is selective to said etching and thus substantially prevents the propagation of photoresist microfissures to said material layer.