Polysilicon etch with high selectivity

摘要

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.

主权项

1. A method of removing polysilicon from a wafer, the method comprising:
providing a wafer, wherein the wafer includes:
a polysilicon layer; andan exposed nitride and/or oxide structure; flowing an etchant including a hydrogen-based species and a fluorine-based species towards the wafer, wherein a concentration of the fluorine-based species is between about 0.7% and about 10% by volume and a concentration of the hydrogen-based species is greater than the concentration of the fluorine-based species; 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.