| 摘要 |
In a dry etching method for etching a structure obtained by successively depositing, on a substrate, a gate insulating film, a silicon base film, a tungsten film or an alloy film containing tungsten, the dry etching includes a first process of dry-etching the tungsten film or the alloy film including tungsten, and a second process of dry-etching the silicon base film, and the first process employs, as an etching gas, a gas mixture obtained by mixing O2 gas into a gas including at least C and F, with the flow ratio of the O2 gas being 10~50% by volume percentages. This dry etching method realizes highly-precise dry etching by which a vertical configuration of the poly-metal structure is obtained, and the selection ratio of W with respect to poly-Si can be controlled and, moreover, penetration through the underlying gate oxide film is prevented.
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