Selective etch of films with high dielectric constant with H2 addition

• US 20070056925A1
• Filed: 09/09/2005
• Published: 03/15/2007
• Est. Priority Date: 09/09/2005
• Status: Abandoned Application

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Liu, Shenjian, Chen, Anthony, Lee, Linda
• Application Number:
  US11/223,780
• Publication Number:
  US 20070056925A1
• Time in Patent Office: Days
• US Class Current: 216/67
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31122 of layers not containing Si, e.g. PZT, Al2O3
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

A method for selectively etching a high k layer with respect to a silicon based material is provided. The high k layer is placed into an etch chamber. An etchant gas is provided into the etch chamber, wherein the etchant gas comprises H₂. A plasma is generated from the etchant gas to selectively etch the high k layer with respect to a silicon based material.

Claims

1. A method for selectively etching a high k layer with respect to a silicon based material, comprising:

placing the high k layer into an etch chamber;

providing an etchant gas into the etch chamber, wherein the etchant gas comprises H₂; and

generating a plasma from the etchant gas to selectively etch the high k layer with respect to the silicon based material.

2. The method, as recited in claim 1, wherein the high k dielectric layer is an oxide layer.

3. The method, as recited in claim 2, wherein the etchant gas further comprises a halogen containing component.

4. The method, as recited in claim 3, wherein the etchant gas further comprises a noble gas.

5. The method, as recited in claim 1, wherein the etchant gas further comprises BCl₃ and an inert gas.

6. The method, as recited in claim 5, wherein the etchant gas has a volume H₂ to BCl₃ flow ration between 0.2-5:

1.

7. The method, as recited in claim 6, wherein the etchant gas has a volume inert gas flow of less than 500 sccm.

8. The method, as recited in claim 7, wherein the etchant gas further comprises Cl₂.

9. The method, as recited in claim 8, wherein the etchant gas has a volume Cl₂ to BCl₃ flow ratio between 0-0.5:

1.

10. The method, as recited in claim 1, wherein the etchant gas further comprises BCl₃ and Cl₂.

11. The method, as recited in claim 10, wherein the etchant gas has a volume H₂ to BCl₃ flow ration between 0.2-5:

1.

12. The method, as recited in claim 11, wherein the etchant gas has a volume Cl₂ to BCl₃ flow ratio between 0-0.5:

1.

13. The method, as recited in claim 12, wherein the silicon based material is at least one of silicon and silicon nitride and wherein the high k layer is at least one of Hf silicate, HfO₂, Zr silicate, ZrO₂, Al₂O₃, La₂O₃, SrTiO₃, SrZrO₃, TiO₂, and Y₂O₃.

14. The method, as recited in claim 13, wherein the silicon based material forms a layer, further comprising etching the silicon based material layer subsequent to selectively etching the high k layer.

15. A semiconductor devices formed by the method of claim 1.

16. A method for etching a stack with a high k layer over a silicon based layer, comprising:

placing the stack into an etch chamber;

selectively etching the high k layer with respect to the silicon based layer, comprising;

providing a high k layer etchant gas into the etch chamber, wherein the high k layer etchant gas comprises H₂; and

generating a plasma from the high k layer etchant gas to selectively etch the high k layer with respect to the silicon based layer;

stopping the selectively etching the high k layer; and

selectively etching the silicon based layer with respect to the high k layer.

17. The method, as recited in claim 16, wherein the high k layer etchant gas further comprises BCl₃ and Cl₂ and wherein the silicon based layer is formed of a silicon based material comprising at least one of silicon and silicon nitride.

18. The method, as recited in claim 17, wherein the high k layer etchant gas has a volume H₂ to BCl₃ flow ration between 0.2-5:

1 and wherein the silicon based material is silicon.

19. The method, as recited in claim 18, wherein the high k layer etchant gas has a volume Cl₂ to BCl₃ flow ratio between 0-0.5:

1.

20. An apparatus for forming flash memory with a high k dielectric layer over a silicon based layer, comprising:

a plasma processing chamber, comprising;

a chamber wall forming a plasma processing chamber enclosure;

a substrate support for supporting a substrate within the plasma processing chamber enclosure;

a pressure regulator for regulating the pressure in the plasma processing chamber enclosure;

at least one electrode for providing power to the plasma processing chamber enclosure for sustaining a plasma;

a gas inlet for providing gas into the plasma processing chamber enclosure; and

a gas outlet for exhausting gas from the plasma processing chamber enclosure;

a gas source in fluid connection with the gas inlet, comprising;

an H₂ gas source;

a BCl₃ gas source; and

a Cl₂ gas source;

a controller controllably connected to the gas source and the at least one electrode, comprising;

at least one processor; and

computer readable media comprising;

computer readable code for selectively etching the high k layer with respect to the silicon based layer, comprising;

computer readable code for providing H₂ from the H₂ gas source;

computer readable code for providing BCl₃ from the BCl₃ gas source;

computer readable code for providing Cl₂ from the Cl₂ gas source; and

computer readable code for generating a plasma from the H₂, BCl₃, and Cl₂ to selectively etch the high k layer with respect to the silicon based layer;

computer readable code to stop the selectively etching the high k layer with respect to the silicon based layer; and

computer readable code for selectively etching the silicon based with respect to the high k layer.