We carry out contact-hole etching of SiO2 with a high selectivity over the underlying Si using a hexthode-type wide-gap plasma etcher. In spite of the low power density in the plasma, heavy fluorocarbon deposition was observed. The amount of deposition is thought to depend on the bias voltage near the surface of the wafer. Selectivity is low in smaller holes (< empty set 0.8 mu m), since the deposition radicals are shaded and cannot reach the bottom of the holes. In larger holes (> empty set 0.8 mu m), however, selectivity is very high (>50), and almost infinite in a hole of empty set 2.0 mu m in diameter. Moreover, sidewall deposition is enough to prevent retardation of the resist even in smaller holes. As a result, quite unique hole-size dependent etching characteristics were obtained, such as tapered etching for smaller holes and high selectivity etching for larger holes. This oxide etcher is applicable when large shallow holes and small deep holes must be etched at the same time.