Technique for etching monolayer and multilayer materials

• US 9,153,453 B2
• Filed: 02/10/2012
• Issued: 10/06/2015
• Est. Priority Date: 02/11/2011
• Status: Active Grant

• Current Assignee: Brookhaven Science Associates, LLC (Government of the United States of America), Lcc Uchicago Argonne, UChicago Argonne LLC (University of Chicago)
• Original Assignee: Brookhaven Science Associates, LLC (Government of the United States of America), UChicago Argonne LLC (University of Chicago)
• Inventors: Conley, Raymond P., Divan, Ralu, Macrander, Albert, Bouet, Nathalie C. D.
• Primary Examiner(s): Oh, Jaehwan
• Application Number:
  US13/371,124
• Publication Number:
  US 20120205785A1
• Time in Patent Office: 1,334 Days
• Field of Search: 438/257, 438/386, 438/703, 438/706, 438/721
• US Class Current: 1/1
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: C23F 4/00 Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
• CPC Class Codes: G21K 1/062 Devices having a multilayer structure
• CPC Class Codes: G21K 2201/067 Construction details
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi₂/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF₃, Cl₂, and O₂ with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.

Claims

1. A process for etching a single layer of metal silicide or a metal silicide and silicon based multilayer material comprising,

(a) obtaining a sample of the single layer of metal silicide or the metal silicide and silicon based multilayer material to be etched;

and

(b) performing a one-step reactive ion etching process in combination with inductively coupled plasma etching on the sample using a gas mixture containing SF₆ and O₂, and using radio frequency power, wherein the SF₆ is from about 89% to about 93% of the gas mixture, and the O₂ is from about 11% to about 7% of the gas mixture, and wherein each of either (i) the etched single layer of metal silicide or (ii) the metal silicide and silicon based multilayer each has a growth thickness between 1 and 21 microns.

2. The process according to claim 1, wherein the single layer of metal silicide or metal silicide and silicon based multilayer material is a thin single layer or thin multilayer.

3. The process according to claim 1, wherein the sample is a WSi₂/Si multilayer.

4. The process according to claim 1, wherein the single layer of metal silicide is WSi₂, VSi₂, or MoSi₂.

5. The process according to claim 1, wherein the metal silicide and silicon based multilayer is WSi₂/Si, MoSi₂/Si, VSi₂/Si, or any combination thereof.

6. The process according to claim 1, wherein the SF₆ is about 91% of the gas mixture.

7. The process according to claim 1, wherein the O₂ is about 9% of the gas mixture.

8. The process according to claim 1, wherein the sample is a WSi₂/Si multilayer.

9. The process according to claim 1, wherein the SF₆ is from about 90% to about 92% of the gas mixture, and the O₂ is from about 10% to about 8% of the gas mixture.

10. The process according to claim 1, where the SF₆ is about 91% of the gas mixture, and the O₂ is about 9% of the gas mixture.

11. The process according to claim 1, wherein the sample is a WSi₂/Si multilayer, the SF₆ is about 91% of the gas mixture, and the O₂ is about 9% of the gas mixture.

12. The process according to claim 1, wherein the SF₆ is from about 90% to about 92% of the gas mixture, and the O₂ is from about 10% to about 8% of the gas mixture.

13. The process according to claim 1, where the SF₆ is about 91% of the gas mixture, and the O₂ is about 9% of the gas mixture.

14. The process according to claim 1, wherein the sample is a WSi₂/Si multilayer, the SF₆ is about 91% of the gas mixture, and the O₂ is about 9% of the gas mixture.

15. A process for etching a single layer of metal silicide or a metal silicide and silicon based multilayer material comprising,

(a) obtaining a sample of the single layer of metal silicide or the metal silicide and silicon based multilayer material to be etched;

and

(b) performing a one-step reactive ion etching and inductively coupled plasma etching on the sample using a gas mixture containing CHF₃, Cl₂, and O₂ and using radio frequency power and inductively coupled plasma power, wherein the gas mixture is about 22% to about 48% CHF₃, about 76% to about 50% Cl₂, and about 2% O₂.

17. The process according to claim 15, wherein the sample is a WSi₂/Si multilayer.

18. The process according to claim 15, wherein the gas mixture is about 22% to about 24% CHF₃, about 76% to about 74% Cl₂, and 2% O₂.

19. The process according to claim 15, wherein the gas mixture is about 23% CHF₃, about 75% Cl₂, and about 2% O₂.

20. The process according to claim 15, wherein the CHF₃ is about 23% of the gas mixture.

21. The process according to claim 15, wherein the Cl₂ is about 75% of the gas mixture.

22. The process according to claim 15, wherein the O₂ is about 2% of the gas mixture.

23. The process according to claim 15, wherein the radio frequency power is from about 10 to about 50 watts.

24. The process according to claim 15, wherein the inductively coupled plasma power is about 350 watts.

25. The process according to claim 15, further comprising the step of adjusting the pressure, wherein the pressure is about 10 mTorr.

26. The process according to claim 15, further comprising the step of adjusting the temperature, wherein the temperature is about room temperature.

27. The process according to claim 15, further comprising the step of adjusting the temperature, wherein the temperature is from about 20°

C. to about 25°

C.

32. The process according to claim 15, wherein the masking material is a chemically amplified, epoxy based negative resist.

33. The process according to claim 15, wherein the masking material is a copolymer resist.

35. The process according to claim 15, further comprising the step of limiting the etching by applying a nickel hard-mask to the surface of the sample.

16. A process for etching a single layer of metal silicide or metal silicide and silicon based multilayer material comprising,

(a) obtaining a sample of the single layer of metal silicide or the metal silicide and silicon based multilayer material to be etched;

(b) limiting the extent of etching by applying to the sample a masking material; and

(c) performing a one-step reactive ion etching and inductively coupled plasma etching on the sample using a gas mixture containing CHF₃, Cl₂, and O₂ and using radio frequency power and inductively coupled plasma power wherein the gas mixture is about 23% CHF₃, about 75% Cl₂, and about 2% O₂.

28. The process according to claim 16, wherein the masking material is hard-mask or a photo-resist.

29. The process according to claim 16, wherein the masking material is a Ni- or Cr-hardened mask.

30. The process according to claim 16, wherein the masking material is a Ni-hardened mask.

31. The process according to claim 16, wherein the masking material is a polymethylmethacrylate resist.

34. The process according to claim 16, wherein the masking material is a mixture of polymethylmethacrylate and methacrylic acid.

36. The process according to claim 16, wherein the sample is a WSi₂/Si multilayer having a nickel hard-mask, the radio frequency power is from about 10 to about 50 watts, the inductively coupled plasma power is about 350 watts, the pressure is about 10 mTorr, and the temperature is about room temperature.

37. A series of etched tungsten silicide/silicon multilayers comprising etched metal silicide and silicon based multilayers having a growth thickness of between 1 and 21 microns after being one-step etched by reactive ion etching alone or in combination with inductively coupled plasma etching using a gas mixture containing SF₆ and O₂, wherein the SF₆ is about 91% of the mixture and the O₂ is about 9% of the mixture.

38. A series of etched tungsten silicide/silicon multilayers comprising sidewalls, a surface, and a passivation layer on said surface after being one-step etched by reactive ion etching and inductively coupled plasma etching using a gas mixture containing CHF₃, Cl₂, and O₂ to the sample, wherein the CHF₃ is about 23% of the mixture, the Cl₂ is about 75% of the mixture, and the O₂ is about 2% of the mixture.