US Patent 9741563 Hybrid stair-step etch

A method for forming a stair-step structure in a substrate is provided, wherein the substrate has an organic mask, comprising at least one cycle, wherein each cycle comprises a) depositing a hardmask over the organic mask, b) trimming the organic mask, c) etching the substrate, d) trimming the organic mask, wherein there is no depositing a hardmask between etching the substrate and trimming the organic mask, e) etching the substrate, and f) repeating steps a-e a plurality of times forming the stair-step structure.