Patent ID: 7910489

Claim:
A method for etching features into an etch layer disposed below a photoresist mask without an intermediate hardmask, comprising: providing a plurality of etch cycles, wherein each etch cycle comprises: providing a deposition etch phase that etches features into the etch layer and deposits polymer on sidewalls of the features and over the photoresist, wherein the deposition etch phase comprises a single step which simultaneously etches the etch layer and deposits polymer on sidewalls of the features, wherein the deposition etch phase includes providing a gas including CF 4 and H 2 ; and providing a cleaning phase that removes polymer deposited on the sidewalls; wherein, immediately after the plurality of etch cycles, the etch features have bottoms and sidewalls that from bottom to top make an angle between 88° to 90° with the bottom of the features, wherein the providing a plurality of cycles comprises providing 10 to 100 cycles.