Patent ID: 9607847
Date: 2017-03-28
CPC Classifications: G01J,H01L

Claim:
1. A method of forming a cavity in a substrate comprising: forming a masking layer on the substrate; forming an opening in the masking layer; performing a first cavity etch through the opening to form a cavity under the opening wherein the first cavity etch etches both laterally and vertically; depositing a polymer through the opening onto the bottom and sidewalls of the cavity wherein the polymer is thicker on the bottom of the cavity than on the sidewalls of the first cavity; removing the polymer from the sidewalls of the first cavity; performing a second cavity etch through the opening and etching the sidewalls of the cavity to increase a width of the cavity without increasing a depth of the cavity, wherein the depth of the cavity is non-uniform across the width; and removing the polymer from the cavity.