Patent ID: 8048738

Claim:
A method for forming a semiconductor device, the method comprising: forming a dielectric layer over a substrate; forming a select gate layer over the dielectric layer; etching the select gate layer at a first etch rate to form a first portion of a sidewall of a select gate and to leave remaining portions of the select gate layer covering the dielectric layer, wherein the step of etching the select gate layer at the first etch rate includes using an oxidizing agent to oxidize at least a top portion of the substrate underlying the dielectric layer to form an oxide layer below the dielectric layer, wherein the oxidizing agent is selected from a group consisting of oxygen and helium oxide; etching the select gate layer at a second etch rate lower than the first etch rate to form a second portion of the sidewall of the select gate, wherein the step of etching the select gate layer at the second etch rate includes removing only a top portion of the dielectric layer, wherein the second etch rate is lower than the first etch rate due to a variation in at least one of an etch power, an etch bias, and an etch chemistry associated with the respective etching step; removing the oxide layer and any remaining portion of the dielectric layer to expose a portion of the substrate; forming a charge storage layer overlying exposed portion of the substrate and the sidewall of the select gate; forming a control gate layer overlying the charge storage layer; and forming a control gate by patterning the control gate layer and the charge storage layer.