Methods of fabricating a word-line spacer for wide over-etching window on outside diameter (od) and strong fence

Abstract

A method of fabricating word-line spacers comprising the following steps. A substrate having an inchoate split-gate flash memory structure formed thereover is provided. A conductive layer is formed over the substrate and the inchoate split-gate flash memory structure. The conductive layer having: a upper portion and lower vertical portions over the inchoate split-gate flash memory structure; and lower horizontal portions over the substrate. A dual-thickness oxide layer is formed over the conductive layer and has a greater thickness over the upper portion of the conductive layer. The oxide layer is partially etched back to remove at least the oxide layer from over the lower horizontal portions of the conductive layer to expose the underlying portions of the conductive layer. Then etching: away the exposed portions of the conductive layer over the substrate; and through at least a portion of the thinned oxide layer and into the exposed underlying portion of the conductive layer to expose a portion of the inchoate split-gate flash memory structure and to form the word-line spacers adjacent the inchoate split-gate flash memory structure.