METHOD AND SYSTEM FOR DRY ETCHING A METAL NITRIDE

• US 20080230519A1
• Filed: 03/23/2007
• Published: 09/25/2008
• Est. Priority Date: 03/23/2007
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Takahashi, Hiroyuki
• Granted Patent: US 7,815,814 B2
• Time in Patent Office: Days
• US Class Current: 216/64
• CPC Class Codes: H01L 21/31122 of layers not containing Si, e.g. PZT, Al2O3
• CPC Class Codes: H01L 21/32136 using plasmas

Abstract

A method and system of etching a metal nitride, such as titanium nitride, is described. The etching process comprises introducing a process composition having a halogen containing gas, such as Cl₂, HBr, or BCl₃, and a fluorocarbon gas having the chemical formula C_xH_yF_z, where x and z are equal to unity or greater and y is equal to 0 or greater.

Claims

1. A method of etching a metal containing layer on a substrate, comprising:

disposing said substrate having a metal nitride layer in a plasma processing system;

elevating the temperature of said substrate above approximately 30 degrees C.;

introducing a process composition comprising a halogen-containing gas and a fluorocarbon gas to said plasma processing system, wherein said fluorocarbon gas comprises the chemical formula C_xH_yF_z, where x and z are equal to unity or greater and y is equal to 0 or greater;

forming a plasma from said process composition in said plasma processing system; and

exposing said substrate to said plasma in order to etch said metal nitride layer.

2. The method of claim 1, wherein said disposing comprises disposing a substrate having a titanium nitride layer.

3. The method of claim 1, wherein said introducing said process composition further comprises introducing an inert gas.

4. The method of claim 3, wherein said introducing said inert gas comprises introducing a noble gas.

5. The method of claim 1, wherein said introducing said halogen containing gas comprises introducing Cl₂, HBr, or BCl₃, or a combination of two or more thereof.

6. The method of claim 5, wherein said introducing said fluorocarbon gas comprises introducing CF₄, CHF₃, or CH₂F₂, or a combination of two or more thereof.

7. The method of claim 1, wherein said introducing said process composition comprises introducing Cl₂, HBr, or BCl₃, or a combination of two or more thereof, and CHF₃.

8. The method of claim 1, wherein said introducing said process composition comprises introducing BCl₃ and CHF₃.

9. The method of claim 1, wherein said disposing comprises disposing a substrate having a hafnium containing layer underlying said metal nitride layer.

10. The method of claim 9, wherein said disposing a substrate having a hafnium containing layer comprises disposing a substrate having a SiO₂ layer underlying said hafnium containing layer.

11. The method of claim 1, wherein said disposing comprises disposing a substrate having a polysilicon layer overlying said metal nitride layer.

12. The method of claim 11, wherein said introducing said process composition comprises introducing BCl₃ and CHF₃, and wherein the flow ratio between said BCl₃ and said CHF₃ ranges from approximately 50% to approximately 95%.

13. The method of claim 11, wherein said introducing said process composition comprises introducing BCl₃ and CHF₃, and wherein the flow ratio between said BCl₃ and said CHF₃ ranges from approximately 75% to approximately 85%.

14. The method of claim 11, wherein said introducing said process composition comprises introducing BCl₃ and CHF₃, and wherein exposing said substrate to said plasma to facilitate said pattern etching comprises achieving an etch selectivity between said metal nitride layer and said poly-crystalline silicon layer greater than or equal to approximately 3-to-1.

15. The method of claim 1, wherein said elevating comprises elevating the temperature to approximately 30 degrees C. and greater.

16. The method of claim 1, wherein said elevating comprises elevating the temperature to approximately 50 degrees C. and greater.

17. The method of claim 1, wherein said forming said plasma comprises capacitively coupling power to said plasma, or inductively coupling power to said plasma, or both.

18. The method of claim 1, wherein said forming said plasma comprises coupling radio frequency (RF) power to a substrate holder upon which said substrate rests.

19. The method of claim 1, wherein said forming said plasma comprises coupling radio frequency (RF) power to an electrode positioned opposite a substrate holder upon which said substrate rests.

20. The method of claim 1, wherein the substrate includes a mask layer defining a pattern therein overlaying said metal nitride layer and said exposing etches said pattern into said metal nitride layer.

21. A plasma processing system for etching a metal nitride layer on a substrate, comprising;

a plasma processing chamber configured to facilitate the formation of a plasma therein in order to etch said metal nitride layer;

a first gas supply system coupled to said plasma processing chamber and configured to introduce BCl₃ to said plasma processing chamber;

a second gas supply system coupled to said plasma processing chamber and configured to introduce a fluorocarbon gas to said plasma processing system; and

a controller coupled to said plasma processing chamber, said first gas supply and said second gas supply and configured to execute a process recipe including;

introducing BCl₃ into said plasma processing chamber, and

introducing said fluorocarbon gas having the chemical formula C_xH_yF_z, where x and z are equal to unity or greater and y is equal to 0 or greater, into said plasma processing chamber, wherein said controller introduces the BCl₃ and fluorocarbon gas at predetermined flow rates.