Si and SiO2 Etching under Low Self-Bias Voltage

Si and SiO2 reactive ion etching and the associated radiation damage were investigated employing CF4 in the low self-bias voltage region (less than 100 V). The etching was carried out using the substrate tuning method. In the low self-bias voltage region, both Si etching and SiO2 etching proceed accompanied by the polymerization of CF x (x=0–3) radicals generated from the dissociation of CF4. The polymer deposited on the surface is decomposed by the subsequent ion bombardment to form F and CF x radicals, which take part in the etching and the polymer formation reaction again. The radiation damage induced in the Si by energetic fluorocarbons depends strongly on the magnitude of the self bias. However, the damage induced by tens of volts can easily be removed.