Plasma for patterning advanced gate stacks

• US 20070099428A1
• Filed: 10/05/2006
• Published: 05/03/2007
• Est. Priority Date: 10/28/2005
• Status: Abandoned Application

• Current Assignee: IMEC International
• Original Assignee: Interuniversitair Micro-Electronica Centrum VZW (IMEC International)
• Inventors: Shamiryan, Denis, Boullart, Werner, Demand, Marc, Paraschiv, Vasile
• Application Number:
  US11/544,351
• Publication Number:
  US 20070099428A1
• Time in Patent Office: Days
• US Class Current: 438/712
• CPC Class Codes: H01L 21/2807 the final conductor layer next to the insulator being Si or Ge or C and their alloys except Si
• CPC Class Codes: H01L 21/28088 the final conductor layer next to the insulator being a composite, e.g. TiN
• CPC Class Codes: H01L 21/31122 of layers not containing Si, e.g. PZT, Al2O3
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 29/513 the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/517 the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence

Abstract

A plasma composition and its use in a method for the dry etching of a stack of at least one material chemically too reactive towards the use of a Cl-based plasma are provided. Small amounts of nitrogen (5% up to 10%) can be added to a BCl₃ comprising plasma and used in an anisotropical dry etching method whereby a passivation film is deposited onto the vertical sidewalls of stack etched for protecting the vertical sidewalls from lateral attack such that straight profiles can be obtained.

Claims

1. A dry-etch plasma composition for preserving a vertical profile of a structure comprising a stack of layers, wherein a removable water-soluble film is deposited onto the sidewalls of the stack from the plasma composition during dry-etch patterning of the stack, such that lateral attack of the patterned stack is avoided.

2. The plasma composition of claim 1, wherein the plasma comprises a boron-halogen compound and nitrogen.

3. The plasma composition of claim 2, further comprising an inert compound.

4. The plasma composition of claim 2, wherein a ratio of the boron-halogen compound to nitrogen is from 19:

1 to 9;

1.

5. The plasma composition of claim 2, wherein the boron-halogen compound is BCl₃.

6. The plasma composition of claim 1, wherein the stack of layers is a metal gate-comprising stack.

7. The plasma composition of claim 6, wherein the metal gate-comprising stack comprises TaN or TaN/TiN.

8. The plasma composition of claim 6, wherein at least one layer of the stack of layers is a germanium-comprising layer.

9. The plasma composition of claim 8, wherein the germanium layer is situated upon a layer to be patterned by the plasma composition.

10. The plasma composition of claim 1, wherein the substrate bias is different from zero.

11. The plasma composition of claim 1, wherein the plasma power is from 100 W to 1200 W.

12. The plasma composition of claim 11, wherein the plasma power is about 450 W.

13. The plasma composition of claim 1, wherein the pressure in the plasma chamber is from 0.666 Pa to 10.665 Pa.

14. The plasma composition of claim 1, wherein the pressure in the plasma chamber is 0.666 Pa.

15. The plasma composition of claim 1, wherein a temperature of the plasma during patterning is below 100°

C.

16. The plasma composition of claim 1, wherein a temperature of the plasma during patterning is about 60°

C.

17. The plasma composition of claim 1, wherein the plasma consists of a boron-halogen compound and nitrogen, and wherein from 5% to 10% of the total plasma composition is nitrogen.

18. The plasma composition of claim 1, wherein the plasma consists of a boron-halogen compound and nitrogen, and wherein less than 10% of the total plasma composition is nitrogen.

19. The plasma composition of claim 1, wherein the plasma consists of a boron-halogen compound and nitrogen, and wherein less than 8% of the total plasma composition is nitrogen.

20. The plasma composition of claim 1, wherein the plasma is a BCl₃ plasma wherein 5% of the total plasma composition is nitrogen.

21. An anisotropical dry etching method for patterning a stack of layers to create a vertical structure, the method comprising the steps of:

patterning a stack of layers to create a vertical structure by dry etching using a plasma composition comprising a boron-halogen compound and nitrogen, wherein a protective and water-soluble film is deposited from the plasma onto vertical sidewalls of the structure during dry etching, such that a vertical profile of the structure is preserved and lateral attack is avoided during dry etching; and

removing the film from the structure.

22. The method of claim 21, wherein the film is removed by a wet removal process using water.

23. The method of claim 21, wherein a ratio of boron-halogen compound to nitrogen is from 19:

1 to 9;

1.

24. The method of claim 21, wherein the boron-halogen compound is BCl₃.

25. The method of claim 21, wherein the plasma further comprises an inert compound.

26. The method of claim 21, wherein the stack of layers is a metal gate-comprising stack.

27. The method of claim 26, wherein the metal gate-comprising stack comprises TaN or TaN/TiN.

28. The method of claim 26, wherein at least one layer of the stack of layers comprises germanium.

29. The method of claim 28 wherein the germanium-comprising layer is situated upon a layer to be patterned by the plasma composition.

30. The method of claim 21, wherein a substrate bias during patterning is different from zero.

31. The method of claim 21, wherein a plasma power during patterning is from 100 W to 1200 W.

32. The method of claim 21, wherein a plasma power during patterning is about 450 W.

33. The method of claim 21, wherein a pressure in the plasma chamber during patterning is from 0.666 Pa to 10.665 Pa.

34. The method of claim 21, wherein a pressure in the plasma chamber during patterning is 0.666 Pa.

35. The method of claim 21, wherein the temperature of the plasma during patterning is below 100°

C.

36. The method of claim 21, wherein the temperature of the plasma during patterning is about 60°

C.

37. The method of claim 21, wherein the plasma consists of a boron-halogen compound and nitrogen, and wherein from 5% to 10% of the total plasma composition is nitrogen.

38. The method of claim 21, wherein the plasma consists of a boron-halogen compound and nitrogen, and wherein less than 10% of the total plasma composition is nitrogen.

39. The method of a claim 21, wherein the plasma consists of a boron-halogen compound and nitrogen, and wherein less than 8% of the total plasma composition is nitrogen.

40. The method of claim 21, wherein the plasma is a BCl₃ plasma wherein 5% of the total plasma composition is nitrogen.