Technique for etching monolayer and multilayer materials
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 WSi 2 /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, CHF 3 , Cl 2 , and O 2 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.
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 SF 6 and O 2 , and using radio frequency power, wherein the SF 6 is from about 89% to about 93% of the gas mixture, and the O 2 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 WSi 2 /Si multilayer.
4. The process according to claim 1 , wherein the single layer of metal silicide is WSi 2 , VSi 2 , or MoSi 2 .
5. The process according to claim 1 , wherein the metal silicide and silicon based multilayer is WSi 2 /Si, MoSi 2 /Si, VSi 2 /Si, or any combination thereof.
6. The process according to claim 1 , wherein the SF 6 is about 91% of the gas mixture.
7. The process according to claim 1 , wherein the O 2 is about 9% of the gas mixture.
8. The process according to claim 1 , wherein the sample is a WSi 2 /Si multilayer.
9. The process according to claim 1 , wherein the SF 6 is from about 90% to about 92% of the gas mixture, and the O 2 is from about 10% to about 8% of the gas mixture.
10. The process according to claim 1 , where the SF 6 is about 91% of the gas mixture, and the O 2 is about 9% of the gas mixture.
11. The process according to claim 1 , wherein the sample is a WSi 2 /Si multilayer, the SF 6 is about 91% of the gas mixture, and the O 2 is about 9% of the gas mixture.
12. The process according to claim 1 , wherein the SF 6 is from about 90% to about 92% of the gas mixture, and the O 2 is from about 10% to about 8% of the gas mixture.
13. The process according to claim 1 , where the SF 6 is about 91% of the gas mixture, and the O 2 is about 9% of the gas mixture.
14. The process according to claim 1 , wherein the sample is a WSi 2 /Si multilayer, the SF 6 is about 91% of the gas mixture, and the O 2 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 CHF 3 , Cl 2 , and O 2 and using radio frequency power and inductively coupled plasma power, wherein the gas mixture is about 22% to about 48% CHF 3 , about 76% to about 50% Cl 2 , and about 2% O 2 .
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 CHF 3 , Cl 2 , and O 2 and using radio frequency power and inductively coupled plasma power wherein the gas mixture is about 23% CHF 3 , about 75% Cl 2 , and about 2% O 2 .
17. The process according to claim 15 , wherein the sample is a WSi 2 /Si multilayer.
18. The process according to claim 15 , wherein the gas mixture is about 22% to about 24% CHF 3 , about 76% to about 74% Cl 2 , and 2% O 2 .
19. The process according to claim 15 , wherein the gas mixture is about 23% CHF 3 , about 75% Cl 2 , and about 2% O 2 .
20. The process according to claim 15 , wherein the CHF 3 is about 23% of the gas mixture.
21. The process according to claim 15 , wherein the Cl 2 is about 75% of the gas mixture.
22. The process according to claim 15 , wherein the O 2 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.
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.
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.
34. The process according to claim 16 , wherein the masking material is a mixture of polymethylmethacrylate and methacrylic acid.
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.
36. The process according to claim 16 , wherein the sample is a WSi 2 /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 SF 6 and O 2 , wherein the SF 6 is about 91% of the mixture and the O 2 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 CHF 3 , Cl 2 , and O 2 to the sample, wherein the CHF 3 is about 23% of the mixture, the Cl 2 is about 75% of the mixture, and the O 2 is about 2% of the mixture.