| 摘要 |
The method of present invention etches a layer of polysilicon formed on a substrate disposed within a substrate processing chamber. The method flows an etchant gas including sulfur hexafluoride, an oxygen source and a nitrogen source into the processing chamber and ignites a plasma from the etchant gas to etch the polysilicon formed over the substrate. In a preferred embodiment, the etchant gas consists essentially of SF6, molecular oxygen (O2) and molecular nitrogen (N2). In a more preferred embodiment the etchant gas includes a volume ratio of molecular oxygen to the sulfur hexafluoride of between 0.5:1 and 1:1 inclusive and a volume ratio of the sulfur hexafluoride to molecular nitrogen of between 1:1 and 4:1 inclusive. In an even more preferred embodiment, the volume ratio of O2 to sulfur hexafluoride is between 0.5:1 and 1:1 inclusive and the volume ratio of sulfur hexafluoride to N2 is between 1.5:1 and 2:1 inclusive.
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