Method for reducing dielectric overetch using a dielectric etch stop at a planar surface

Abstract

A substantially planar surface coexposes conductive or semiconductor features and a dielectric etch stop material. In a preferred embodiment, the conductive or semiconductor features are pillars forming vertically oriented diodes. A second dielectric material, different from the dielectric etch stop material, is deposited on the substantially planar surface. A selective etch etches a hole or trench in the second dielectric material, so that the etch stops on the conductive or semiconductor feature and the dielectric etch stop material. In a preferred embodiment the substantially planar surface is formed by filling gaps between the conductive or semiconductor features with a first dielectric such as oxide, recessing the oxide, filling with a second dielectric such as nitride, then planarizing to coexpose the nitride and the conductive or semiconductor features.