ION-BEAM-ASSISTED ETCHING OF SI WITH FLUORINE AT LOW-TEMPERATURES

The ion-assisted etching of Si with F atoms has been studied over the temperature range from 77 K to room temperature. Separately controllable beams of F atoms and 1 keV Ar+ ions are used in an ultrahigh-vacuum environment. Neutral etch products are measured with modulated beam mass spectrometry. The ion-assisted etch rate is seen to increase as the temperature is decreased whereas the spontaneous etch rate goes to zero at low temperatures. The nature of the etch products is essentially independent of temperature over this temperature range. Evidence is presented indicating that the spontaneous etching of Si by F atoms at 77 K is blocked by the formation and condensation of Si2F6. © 1994 American Institute of Physics.