Patent ID: 8163655

Claim:
A method for making a semiconductor device comprising: forming a first material layer on a substrate; forming a second material layer on the first material layer; forming a sacrificial layer on the second material layer, wherein the sacrificial layer comprises lanthanum oxide (LaO); forming a patterned resist layer on the sacrificial layer; applying a first wet etching process using a first etch solution to the substrate to pattern the sacrificial layer using the patterned resist layer as a mask, resulting in a patterned sacrificial layer; applying an ammonia hydroxide-hydrogen peroxide-water mixture (APM) solution to the substrate to pattern the second material layer, resulting in a patterned second material layer; applying a second wet etching process using a second etch solution to the substrate to pattern the first material layer; and applying a third wet etching process using a third etch solution to remove the patterned sacrificial layer.