Patent ID: 7479458

Claim:
In a plasma processing system, a method for etching a barrier material of a semiconductor substrate, said barrier material selected from the group consisting of SiCN, SiON, and Si 3 N 4 , the method comprising: placing said semiconductor substrate in a plasma processing chamber of said plasma processing system, wherein said semiconductor substrate includes said barrier material and a low-k material, flowing an etchant gas mixture into said plasma processing chamber, wherein said etchant gas mixture comprises CH 3 F, Ar, CF 4 , O 2 , and CO; striking a plasma from said etchant gas mixture, said plasma etching said barrier material and said low-k material, wherein said plasma is configured to etch said barrier material at a first etch rate, said plasma is configured to etch said low-k material at a second etch rate, and said first etch rate is greater than said second etch rate.