Sacrificial layers for use in fabrications of microelectromechanical devices

• US 6,913,942 B2
• Filed: 03/28/2003
• Issued: 07/05/2005
• Est. Priority Date: 03/28/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Reflectvity Incorporated
• Inventors: Patel, Satyadev R., Doan, Jonathan C.
• Primary Examiner(s): TSAI, H JEY
• Application Number:
  US10/402,889
• Publication Number:
  US 20040191946A1
• Time in Patent Office: 830 Days
• Field of Search: 438 48- 56
• US Class Current: 438/48
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81C 1/00476 removing a sacrificial layer B81C1/00912 takes precedence
• CPC Class Codes: B81C 2201/0107 Sacrificial metal

Abstract

A sacrificial layer and a method for applying said sacrificial layer in fabricating microelectromechanical devices are disclosed herein. The sacrificial layer comprises an early transition metal. Specifically, the sacrificial layer comprises an early transition metal element, an early transition metal alloy or an early transition metal silicide.

Claims

1. A method comprising:

providing a substrate;

depositing a sacrificial layer on the substrate, wherein the sacrificial layer comprises an early transition metal;

forming a hinge and a mirror plate of a micromirror device after the sacrificial layer, wherein the hinge comprise an early transition metal nitride and a metalloid nitride;

removing the sacrificial layer using a vapor phase etchant that is a vapor phase noble gas halide or a vapor phase interhalogen so as to release the micromirror device.

2. The method of claim 1, wherein the sacrificial layer comprises an early transition metal element, an early transition metal alloy or an early transition metal silicide.

3. The method of claim 2, wherein the early transition metal element is selected from the group consisting of Ti, Zr, Hf, and Rf.

4. The method of claim 3, wherein the early transition metal element is titanium.

5. The method of claim 2 wherein the early transition metal element is selected from the group consisting of V, Nb, Ta, and Db.

6. The method of claim 5, wherein the early transition metal element is tantalum.

7. The method of claim 2, wherein the early transition metal element is selected from the group consisting of Cr, Mo, W, and Sg.

8. The method of claim 7, wherein the early transition metal element is molybdenum.

9. The method of claim 7, wherein the early transition metal element is tungsten.

10. The method of claim 2, wherein the early transition metal alloy comprises an early transition metal element selected from the group consisting of Ti, Zr, Hf, and Rf.

11. The method of claim 10, wherein the early transition metal element is titanium.

12. The method of claim 2, wherein the early transition metal alloy comprises an early transition metal element selected from the group consisting of V, Nb, Ta, and Db.

13. The method of claim 12, wherein the early transition metal element is tantalum.

14. The method of claim 2, wherein the early transition metal alloy comprises an early transition metal element selected from the group consisting of Cr, Mo, W. and Sg.

15. The method of claim 14, wherein the early transition metal element is molybdenum.

16. The method of claim 14, wherein the early transition metal clement is tungsten.

17. The method of claim 2, wherein the early transition metal suicide comprises an early transition metal element selected from the group consisting of Ti, Zr, Hf, and Rf.

18. The method of claim 17, wherein the early transition metal element is titanium.

19. The method of claim 2, wherein the early transition metal silicide comprises an early transition metal element selected from the group consisting of V, Nb, Ta, and Db.

20. The method of claim 19, wherein the early transition metal element is tantalum.

21. The method of claim 2, wherein the early transition metal suicide comprises an early transition metal element selected from the group consisting of Cr, Mo, W, and Sg.

22. The method of claim 21, wherein the early transition metal element is tungsten.

23. The method of claim 21, wherein the early transition metal element is molybdenum.

24. The method of claim 1 wherein the sacrificial layer comprises one or more early transition metals selected from zirconium, hafnium, vanadium, niobium, chromium.

25. The method of claim 1, wherein the chemical vapor-phase etchant is a mixture of noble gas halide and one or more non-etchant gaseous additives.

26. The method of claim 25, wherein the additive is inert gas.

27. The method of claim 1 wherein the step of forming a hinge and a mirror plate of the micromirror device further comprises:

depositing a second sacrificial layer; and

forming one or more other structures of the micromirror device on the second sacrificial layer.

28. The method of claim 27, wherein the second sacrificial layer comprises one or more sacrificial materials selected from early transition metal element, early transition metal alloy and early transition metal suicide;

and wherein the step of removing the sacrificial layer for releasing the microelectromechanical device further comprises;

removing the second sacrificial layer.

29. The method of claim 1, wherein the step of forming a hinge and a mirror plate of the micromirror device further comprises:

depositing a barrier layer on one or both of the formed hinge and mirror plate of the micromirror device; and

patterning the deposited barrier layer.

30. The method of claim 29, wherein the barrier layer comprises one or more barrier materials selected from early transition metal nitride, early transition metal compound, early transition metal oxide and early transition metal nitride oxide.

31. The method of claim 29, further comprising:

depositing an amorphous silicon layer on the barrier layer, wherein the amorphous silicon layer is removed after releasing the micromirror device.

32. The method of claim 1 wherein the substrate is glass that is transparent to visible light.

33. The method of claim 1 wherein the substrate is a silicon wafer, on which digital integrated circuit and electrode can be formed.

34. The method of claim 27, wherein the micromirror device is part of a spatial light modulator used in a display system.

35. The method of claim 1, further comprising:

depositing another sacrificial layer, wherein the mirror plate s formed on said sacrificial layer; and

the hinge is formed said another sacrificial layer.

36. The method of claim 35, wherein the hinge is formed prior to the mirror plate.

37. The method of claim 35, wherein the hinge is formed after the mirror plate.

38. The method of claim 1, wherein the hinge and mirror arc formed on the same sacrificial layer.

39. The method of claim 1, wherein the hinge is a multi-layered structure;

and the early transition metal nitride and the metalloid nitride are located in different planes.

40. The method of claim 39, wherein the early transition metal nitride is TiN_R or TiSi_xN_x.

41. The method of claim 39, wherein the hinge comprises SiN_x.

42. The method of claim 1, wherein the hinge comprises TiSi_xN_y.

43. The method of claim 1, wherein the hinge further comprises an early transition metal silicon nitride.

44. The method of claim 1, wherein the hinge further comprises a early transition metal oxynitride.

45. The method of claim 1, wherein the hinge further comprises an early transition metal silicon oxynitride.

46. The method of claim 1, wherein the hinge further comprises a silicon carbide.

47. The method of claim 1, wherein the mirror plate comprises an aluminum.

48. The method of claim 1, wherein the mirror plate comprises a titanium.

49. The method of claim 1, wherein the mirror plate comprises a silver.

50. The method of claim 1, wherein the mirror plate comprises a gold.

51. The method of claim 1, wherein the structure layers further comprise aluminum titanium.

52. The method of claim 1, wherein the mirror plate comprises an aluminum silicon.

53. The method of claim 1, wherein the mirror plate comprises an aluminum silicon copper.