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US 5,312,518 AGranted
Dry etching method
AssigneeSony Corporation
InventorShingo Kadomura
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AssigneeSony Corporation
InventorShingo Kadomura
Estimating the term…
A dry etching method whereby an SiO.sub.2 layer and an Si.sub.3 N.sub.4 layer may be etched with high selectivity for each other. As etching gas, such sulfur fluorides as S.sub.2 F.sub.2 are used which, when dissociated by electric discharges, will form SF.sub.x.sup.+ as a main etchant for the SiO.sub.2 layer or F* as a main etchant for the Si.sub.3 N.sub.4 layer and release sulfur in the plasma. When the SiO.sub.2 layer is etched on the Si.sub.3 N.sub.4 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).sub.x, which will, in turn, serve to achieve high selectivity for the underlying layer. The SiO.sub.2 layer can also be etched via an Si.sub.3 N.sub.4 mask patterned into a predetermined shape, in which case sulfur nitride compounds formed on the Si.sub.3 N.sub.4 mask will serve to achieve high selectivity therefor.
A dry etching method for etching a silicon oxide based material layer, comprising providing a silicon substrate, a three-layer gate insulation film being formed on said silicon substrate, a gate electrode formed on said gate insulation film, and an SiO.sub.2 layer covering said gate electrode with said three-layer gate insulation film having a first SiO.sub.2 gate insulation film, a Si.sub.3 N.sub.4 gate insulation film, and a second SiO.sub.2 gate insulation film;
A dry etching method for etching a SiO.sub.2 layer formed on a substrate and masked with a Si.sub.3 N.sub.4 material layer patterned into a predetermined shape by providing a plasma etching gas containing at least one compound selected from S.sub.2 F.sub.2, SF.sub.2, SF.sub.4, and S.sub.2 F.sub.10, and by etching portion of the SiO.sub.2 layer exposed by said Si.sub.3 N.sub.4 material layer.
A dry etching method comprising providing a substrate having a Si.sub.3 N.sub.4 layer and a SiO.sub.2 layer on the Si.sub.3 N.sub.4 layer, creating a plasma etching gas containing a fluorine gas selected from S.sub.2 F.sub.2, SF.sub.2, SF.sub.4 and S.sub.2 F.sub.10, maintaining the substrate at a temperature lower than room temperature, etching the SiO.sub.2 layer while depositing a sulfur material on the Si.sub.3 N.sub.4 layer, and subsequently heating the substrate to remove the sulfur material.
Dependencies are inferred from the claim text.