Patent ID: 7105100

Claim:
A method for etching a substrate, comprising: (a) etching the substrate in a first step, wherein the first step comprises: supplying a first etch gas at a first rate to a first portion of the substrate through a first flow channel; and supplying the first etch gas at a second rate to a second portion of the substrate through a second flow channel, wherein the first rate is different than the second rate, and wherein the first portion is different from the second portion; and (b) etching the substrate in a second step, wherein the first step is different from the second step, and wherein the second step comprises: supplying a second etch gas at a third rate to the first portion of the substrate through the first flow channel; and supplying the second etch gas at a fourth rate to the second portion of the substrate through the second flow channel, wherein the third rate is different that the fourth rate.