Patent ID: 7429533

Claim:
A method for providing features in an etch layer, comprising: forming a sacrificial patterned layer with sacrificial features over an etch layer; forming conformal sidewalls in the sacrificial features, comprising at least two cycles of a sidewall formation process, wherein each cycle comprises: a sidewall deposition phase; and a sidewall profile shaping phase, which shapes the sidewall profile to a vertical profile; selectively removing parts of the sacrificial patterned layer between conformal sidewalls leaving the conformal sidewalls with gaps between the conformal sidewalls where parts of the sacrificial patterned layer were selectively removed; and etching features in the etch layer using the conformal sidewalls as an etch mask, wherein the features in the etch layer are etched through the gaps between the conformal sidewalls where parts of the sacrificial patterned layer were selectively removed.