The use of SF6/O-2 chemistry for polysilicon gate etching at a low temperature in an electron cyclotron resonance plasma etcher is considered. Sidewall angle, polysilicon etch rate, and selectivity to gate oxide and photoresist are reported as functions of temperature in the range -125 degreesC to 25 degreesC. The addition of oxygen to the plasma allows anisotropic etching to be obtained at higher temperatures than with pure SF6. 0.3 mum long gates were formed at -100 degreesC using an etch process with approximate to3:1 selectivity to photoresist and approximate to14:1 selectivity to oxide.