Dual doped polysilicon and silicon germanium etch
AssigneeLam Research Corporation
InventorsC. Robert Koemtzopoulos, Yoko Yamaguchi Adams, Yoshinori Miyamoto, Yousun Kim Taylor
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Abstract
A method for etching a stack with at least one silicon germanium layer over a substrate in a processing chamber is provided. A silicon germanium etch is provided. An etchant gas is provided into the processing chamber, wherein the etchant gas comprises HBr, an inert diluent, and at least one of O2 and N2. The substrate is cooled to a temperature below 40° C. The etching gas is transformed to a plasma to etch the silicon germanium layer.
Claims14
A method of etching a polysilicon layer over a substrate, wherein the polysilicon layer has at least one doped region and at least one undoped region, comprising:
- placing the substrate in a processing chamber;
- providing an etchant gas into the processing chamber, wherein the etchant gas comprises N2, SF6, and at least one of CHF3 and CH2F2;
- and
- transforming the etching gas to a plasma to simultaneously etch the at least one doped region and at least one undoped region of the polysilicon layer;
- and directly thereafter
- providing a polysilicon main etch, comprising:
- providing an etchant gas with at least one of Cl2, HBr, CF4, and O2;
- and
- transforming the etching gas to a plasma to etch the polysilicon layer.
A method for etching a stack with at least one silicon germanium layer over a substrate in a processing chamber and a polysilicon layer over the silicon germanium layer, wherein at least one region of the polysilicon layer is doped and at least one region of the polysilicon layer is undoped, comprising:
- providing a break through etch of the polysilicon layer over the silicon germanium layer, wherein the break through etch simultaneously etches the at least one doped region and the at least one undoped region of the polysilicon layer, comprising:
- providing an etchant gas into the processing chamber, wherein the etchant gas comprises N2, SF6, and at least one of CHF3 and CH2F2;
- and
- transforming the etching gas to a plasma to simultaneously etch the at least one doped region and at least one undoped region of the polysilicon layer;
- directly thereafter
- providing a polysilicon main etch after the break through etch, comprising:
- providing an etchant gas with at least one of Cl2, HBr, CF4, and O2;
- and
- transforming the etching gas to a plasma that etches the polysilicon layer completely through to the silicon germanium layer;
- and
- providing a silicon germanium etch after the polysilicon main etch, comprising:
- providing an etchant gas into the processing chamber, wherein the etchant gas comprises HBr, an inert diluent, and at least one of O2 and N2;
- cooling the substrate to a temperature below 40° C.;
- and
- transforming the etching gas to a plasma to etch the silicon germanium layer.
Dependencies are inferred from the claim text.