Patent ID: 7341953

Claim:
A method for etching features in a dielectric layer over a substrate and disposed below a polymeric hard mask, comprising: forming a patterned photoresist mask over the polymeric hard mask; placing the substrate in a plasma processing chamber; etching mask features into the polymeric hard mask through the photoresist mask, comprising: etching mask features with necks into the hard mask, comprising; providing a mask etchant gas; generating a plasma from the mask etchant gas; and stopping the flow of the mask etchant gas; and treating the mask features to selectively etch away the necks, comprising: providing a treatment gas comprising fluorocarbon, wherein the treatment gas is different than the mask etchant gas; generating a plasma from the treatment gas; and stopping the flow of the treatment gas; etching features into the dielectric layer through the polymeric hard mask, comprising: providing a dielectric layer etch gas, wherein the dielectric layer etch gas is different than the mask etchant gas and the treatment gas; and generating a plasma from the dielectric layer etch gas.