Method for etching silicon carbide

• US 20030087531A1
• Filed: 07/19/2002
• Published: 05/08/2003
• Est. Priority Date: 03/30/2001
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Sadjadi, S.M. Reza, Kang, Sean S., Li, Si Yi
• Granted Patent: US 6,919,278 B2
• Time in Patent Office: Days
• US Class Current: 438/710
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

A system and method for achieving a silicon carbide to low-k dielectric etch selectivity ratio of greater than 1:1 using a chlorine containing gas and either hydrogen (H₂) gas or nitrogen (N₂) gas is described. The method is applied to a semiconductor substrate having a low-k dielectric layer and a silicon carbide layer. The chlorine containing gas is a gas mixture that includes either HCl, BCl₃, Cl₂, or any combination thereof. In one embodiment, the method provides for supplying an etchant gas comprising a chlorine containing gas and a hydrogen (H₂) gas. The etchant gas is then energized to generate a plasma which then etches openings in the silicon carbide at a faster etch rate than the low-k dielectric etch rate. In an alternative embodiment, the etchant gas mixture comprises a chlorine containing gas and a nitrogen (N₂) gas.

Claims

1. A method of plasma etching a layer of silicon carbide comprising:

positioning a semiconductor substrate in a reactor chamber, said semiconductor substrate including a first layer of silicon carbide and a second layer of a low-k dielectric material;

supplying an etchant gas to the chamber, said etchant gas comprising a chlorine containing gas, and a hydrogen (H₂) gas;

energizing the etchant gas into a plasma; and

etching openings in said first silicon carbide layer at a faster rate than said second low-k dielectric layer.

2. The method of claim 1 wherein said etchant gas further comprises a carrier gas which is a noble gas wherein said noble gas is selected from a group consisting of He, Ne, Ar, Kr and Xe.

3. The method of claim 1 wherein said chlorine containing gas is selected from a group consisting of HCl, BCl₃, and Cl₂.

4. The method of claim 3 wherein said silicon carbide to said low-k dielectric etch rate selectivity ratio is greater than 1:

1.

5. The method of claim 3 wherein said silicon carbide to said low-k dielectric etch rate selectivity ratio is greater than 1.5:

1.

6. The method of claim 3 wherein said silicon carbide to said low-k dielectric etch rate selectivity ratio is greater than 2:

1.

7. The method of claim 3 wherein said chlorine containing gas and said hydrogen gas are supplied to the reactor chamber at a flow rate ratio of at least 1:

1.

8. The method of claim 3 wherein said chlorine containing gas and said hydrogen gas are supplied to the reactor chamber at a flow rate ratio of at least 2:

1.

9. The method of claim 3 further comprising applying a minimum pressure of 70 Mtorr to said chamber.

10. The method of claim 3 further comprising an electrode configured to communicate at least 300 Watts of RF power to said etchant gas.

11. The method of claim 3 wherein said low-k dielectric is an organo-silicate glass.

12. The method of claim 3 wherein said etchant gas further comprises a carrier gas which is a noble gas wherein said noble gas is selected from a group consisting of He, Ne, Ar, Kr and Xe.

13. A method of plasma etching a layer of silicon carbide comprising:

positioning a semiconductor substrate in a reactor chamber, said semiconductor substrate including a first layer of silicon carbide and a second layer of a low-k dielectric material;

supplying an etchant gas to the chamber, said etchant gas comprising a chlorine containing gas, and a nitrogen (N₂) gas;

energizing the etchant gas into a plasma; and

etching openings in said first silicon carbide layer at a faster rate than said second low-k dielectric material.

14. The method of claim 13 wherein said etchant gas further comprises a carrier gas which is a noble gas wherein said noble gas is selected from a group consisting of He, Ne, Ar, Kr and Xe.

15. The method of claim 13 wherein said chlorine containing gas is selected from a group consisting of HCl, BCl₃, and Cl₂.

16. The method of claim 15 wherein said silicon carbide to said low-k dielectric etch rate selectivity ratio is greater than 1:

1.

17. The method of claim 15 wherein said silicon carbide to said low-k dielectric etch rate selectivity ratio is greater than 1.5:

1.

18. The method of claim 15 wherein said chlorine containing gas and said nitrogen gas are supplied to the reactor chamber at a flow rate ratio of at least 1:

1.

19. The method of claim 15 wherein said chlorine containing gas and said nitrogen gas are supplied to the reactor chamber at a flow rate ratio of at least 2:

1.

20. The method of claim 15 further comprising applying a minimum pressure of 70 Mtorr to said chamber.

21. The method of claim 15 further comprising an electrode configured to communicate at least 300 Watts of RF power to said etchant gas.

22. The method of claim 15 wherein said low-k dielectric is organo-silicate glass.