The effects of a surface magnetic field on reactive ion etching are described. The surface magnetic field is formed by the construction of a surface‐multimagnetic mirror configuration (SURMAC) cage that consists of permanent magnets arranged inside the wall of a parallel plate rf discharge chamber. The experimental results of ion density, electron temperature, negative self‐bias of an rf‐generated N2plasma, and etching of Si and SiO2with a CF4plasma are obtained with and without the SURMAC cage (rf power 40–520 W, gas pressure 20–100 mTorr). The results show that a surface magnetic field increases the etch rates of Si and SiO2at high power (>250 W) and high pressure (100 mTorr), improves the Si to SiO2selectivity at low power (<200 W) and decreases the magnitude of negative self‐bias at all conditions.