Previous experiments have shown that very high etch rates can be obtained with an rf hollow cathode reactive sputter etching apparatus. This letter shows that hollow cathode etching also permits profile control, without mask undercut or mask erosion. The angle of etching is here varied from 90° (i.e., normal to the etched surface) to 50°, at a constant pressure of CF4and a constant applied rf voltage, by varying the etch conditions. The etch angle is largely independent of the etched material (SiO2or Si).