| 摘要 |
A dry etching method whereby an SiO2 layer and an Si3N4 layer may be etched with high selectivity for each other. As etching gas, such sulfur fluorides as S2F2 are used which, when dissociated by electric discharges, will form SFx+ as a main etchant for the SiO2 layer or F* as a main etchant for the Si3N4 layer and release sulfur in the plasma. When the SiO2 layer is etched on the Si3N4 layer as an underlying layer via a resist mask, nitrogen atoms, removed from the underlying layer upon exposure thereof to the plasma, will combine with sulfur in the plasma to form on the exposed surface thereof such sulfur nitride compounds as polythiazyl (SN)x, which will, in turn, serve to achieve high selectivity for the underlying layer. The SiO2 layer can also be etched via an Si3N4 mask patterned into a predetermined shape, in which case sulfur nitride compounds formed on the Si3N4 mask will serve to achieve high selectivity therefor.
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