Patent ID: 7192880
Filing Date: 2007-03-20
Classification: H01L

Abstract:
1. A method for etching a substrate, comprising: conducting a first etch on an anti-reflective layer and a portion of a hardmask layer to form an opening therein, the first etch being selective to a remaining portion of the hardmask layer; conducting a second etch different from the first etch on the remaining portion, the second etch being less selective than the first etch to the remaining portion, wherein the first etch allows a build-up of polymer on the side walls of the opening and the polymer substantially remains on the side walls during the second etch; and wherein the first etch comprises a mixture of gases having an etching gas, a polymerization gas, and a first etch rate modulator and wherein the second etch comprises a fluorocarbon gas that is both an etching gas and a polymerization gas under a same set of etching parameters and a second etch rate modulator.