Polysilicon etch with high selectivity
AssigneeNovellus Systems, Inc.
InventorsBayu Thedjoisworo, Jack Kuo, David Cheung, Joon Park
Life of this patent
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Abstract
Provided are methods and systems for removing polysilicon on a wafer. A wafer can include a polysilicon layer and an exposed nitride and/or oxide structure. An etchant with a hydrogen-based species, such as hydrogen gas, and a fluorine-based species, such as nitrogen trifluoride, can be introduced. The hydrogen-based species and the fluorine-based species can be activated with a remote plasma source. The layer of polysilicon on the wafer can be removed at a selectivity over the exposed nitride and/or oxide structure that is greater than about 500:1.
Claims24
A method of removing polysilicon from a wafer, the method comprising:
- providing a wafer, wherein the wafer includes:
- a polysilicon layer;
- and
- an exposed nitride and/or oxide structure;
- flowing an etchant including a hydrogen-based species and a fluorine-based species towards the wafer;
- exposing the etchant to a remote plasma to activate the hydrogen-based species and the fluorine-based species;
- and
- removing the polysilicon layer at a selectivity over the exposed nitride and/or oxide structure of greater than about 500:1.
An apparatus for removing polysilicon from a wafer, the apparatus comprising:
- a reaction chamber comprising the wafer, wherein the wafer includes:
- a polysilicon layer;
- and
- an exposed nitride and/or oxide structure
- a plasma source coupled to the reaction chamber and configured to generate a plasma outside the reaction chamber;
- and
- a controller with instructions for performing the following operations:
- (a) flowing an etchant including a hydrogen-based species and a fluorine-based species towards the wafer;
- (b) exposing the etchant to the plasma to activate the hydrogen-based species and the fluorine-based species;
- and
- (c) removing the polysilicon layer at a selectivity over the exposed nitride and/or oxide structure of greater than about 500:1.
Dependencies are inferred from the claim text.