Method for forming planarized etch mask structures over existing topography

Abstract

A method used to create small pattern features over existing topography variations. The method includes providing a substrate having a surface having non-planar surface variations; forming a multi-stack layer over the substrate, by applying a first carbon layer over the substrate, with the resultant first carbon layer having non-planar surface variations corresponding to the non-planar surface variations of the underlying substrate, followed by applying a second planarizing layer over the first carbon layer; depositing a hard mask on the multi-stack layer; forming a patterned layer on the hard mask, the formed patterned layers having features; and performing one or more etch steps to etch the formed patterned layer features into the multi-layer stack. The multi-layer stack has a composite effective mechanical stiffness (E) sufficient to maintain the one or more etched features with minimal feature collapse.