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US 6,110,838 AGranted
Isotropic polysilicon plus nitride stripping
AssigneeTexas Instruments Incorporated
InventorLee M. Loewenstein
Life of this patent
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Abstract
A dry etch process for stripping LOCOS nitride masks (302) with fluorine based removal of oxynitride (312) followed by fluorine plus chlorine based removal of nitride (302) and any silicon buffer layer (303) without removal of pad oxide (304).
Claims13
A method of dry etching polysilicon plus silicon nitride, comprising the steps of:
- (a) exposing polysilicon plus silicon nitride to a gas mixture including fluorine and chlorine sources plus a control gas selected from the group consisting of an oxygen source, a nitrogen source, and a mixture thereof, whereby said polysilicon plus silicon nitride is removed.
A dry etch mixture for etching polysilicon, comprising:
- (a) activated species from a remote excitation of a mixture of a fluorine source, a chlorine source, a nitrogen source, and an oxygen source, wherein said nitrogen source plus said oxygen source is at least about 85% of said mixture.
A method of etching polysilicon, comprising the steps of:
- (a) exposing polysilicon to a gas mixture including fluorine and chlorine sources plus a control gas which includes a nitrogen source, and an oxygen source, wherein said control gas is at least about 85% of said gas mixture .
Dependencies are inferred from the claim text.