We have studied the etching performance of two commercially available low pressure, high density plasma sources and their application for the etching of 0.35 μm features in polysilicon films. The two sources are a rf‐inductively coupled helicon made by Lucas Labs of Sunnyvale, CA and a multipole electron cyclotron resonance (ECR) source made by Wavemat of Plymouth, MI. The sources are mounted on a dual chamber etching platform to remove platform dependent effects. Performance metrics consist of measuring the polysilicon etching rate, etching rate uniformity, and profile control in HBr gas‐phase chemistry. The effect of applied source power, applied rf‐bias power, and reactor pressure on the etching rate and uniformity is examined using a response surface experiment. Profile control is determined by examining nested and isolated lines and trenches using oxide mask/polysilicon/oxide structures. In both sources, high uniformity and vertical profiles are obtained at low reactor pressure, high applied source p...