| 摘要 |
The present invention teaches a method for etching a tungsten silicide (WSix) film overlying a polysilicon film in an enclosed chamber during a semiconductor fabrication process, by the steps of: providing a patterned mask overlying the WSix film thereby providing exposed portions of the WSix film; presenting an etchant chemistry comprising NF3 and HeO2 to the exposed portions of the WSix film at a temperature ranging from -20 DEG C. to 100 DEG C., thereby etching away the exposed portions of the WSix film and simultaneously etching substantially vertical sidewalls in the WSix film, the etching continues into the polysilicon film, thereby forming a WSix/polysilicon stack having substantially vertical sidewalls.
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