Photoresist is etched using a remote thermal (cascaded arc) plasma in Ar/O-2 and Ar/O2N2 mixtures. Very high etch rates, up to 200 nm/s, are achieved at low substrate temperatures (350 K) and low electron and ion temperatures (<0.5 eV). The addition of small amounts of nitrogen (3%) leads to an increase in etch rate. The etch rate in Ar/O-2/N-2 also increases with time during the etching process. The details of the plasma and surface chemistries are not yet well understood. (C) 2003 American Vacuum Society.