Patent ID: 8262920

Claim:
A method for forming features in a silicon layer, comprising: forming a mask with a plurality of mask openings over the silicon layer; depositing a polymer layer over the mask, comprising: flowing a hydrogen free deposition gas comprising C 4 F 8 , wherein the deposition gas consists essentially of C 4 F 8 ; forming a plasma from the deposition gas; depositing a polymer from the plasma for at least 20 seconds; and stopping the depositing the polymer after the at least 20 seconds; opening the deposited polymer layer, comprising: flowing an opening gas; forming a plasma from the opening gas which selectively removes the deposited polymer on bottoms of the plurality of mask openings with respect to deposited polymer on sides of the plurality of mask openings; and stopping the opening when at least some of the plurality of mask features are opened; and etching the silicon layer through the mask and deposited polymer layer, wherein the deposited polymer layer is completely etched away by etching the silicon layer.