Microelectromechanical structure and a method for making the same

• US 7,153,443 B2
• Filed: 03/18/2004
• Issued: 12/26/2006
• Est. Priority Date: 03/28/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Patel, Satyadev, Doan, Jonathan
• Primary Examiner(s): Norton, Nadine
• Assistant Examiner(s): GEORGE, PATRICIA ANN
• Application Number:
  US10/805,610
• Publication Number:
  US 20060266730A1
• Time in Patent Office: 1,013 Days
• Field of Search: 216/58
• US Class Current: 216/58
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81C 1/00793 Avoid contamination, e.g. absorption of impurities or oxidation
• CPC Class Codes: B81C 2201/053 Depositing a protective layers

Abstract

A microstructure and the method for making the same are disclosed herein. The microstructure has structural members, at least one of which comprises an intermetallic compound. In making such a microstructure, a sacrificial material is employed. After completion of forming the structural layers, the sacrificial material is removed by a spontaneous vapor phase chemical etchant.

Claims

1. An etching method comprising:

loading a workpiece into an etching chamber, the workpiece comprising a first area to be removed by a spontaneous vapor phase chemical etchant and a second area to remain after the first area being removed, wherein the second area comprises an intermetallic compound;

providing the spontaneous vapor phase etchant to the etching chamber;

removing the first area while leaving behind the second area; and

wherein the chemical etchant comprises a chemical species that is selected from the group consisting of;

interhalogens and noble gas halides.

2. The method of claim 1, wherein the intermetallic compound comprises an early transition metal selected from column 4 in the periodic table.

3. The method of claim 1, wherein the intermetallic compound comprises an element that is Tc or Re.

4. The method of claim 1, wherein the intermetallic material is selected from the group consisting of NiAl_x, and TiNi_x.

5. The method of claim 1, wherein the intermetallic material is VAl_x, WTe_x, TiFe_x, TiPd_x, AlPd_x, MoPd_x, MoNi_x, MoFe_x, CoCr_x, CoMn_x, NiW_x, NiV_x, NiTi_xAl_y, NbAl_x, MoPd_x, AICu_x, CuZn_x, or TaAl_x.

6. The method of claim 1, wherein the first area comprises a material that is elemental metal, metalloid, metal alloy, metal silicide, W_xN or TaN_x.

7. The method of claim 1, wherein the workpiece is a micromirror array.

8. The method of claim 1, wherein the workpiece is a microelectromechanical device.

9. The method of claim 1, wherein the interhalogen comprises bromine trifluoride.

10. The method of claim 1, wherein the noble gas halide comprises xenon difluoride.

11. The method of claim 1, wherein vapor phase etchant further comprises a diluent gas that is a noble gas.

12. The method of claim 1, wherein the intermetallic compound comprises an early transition metal selected from column 5 in the periodic table.

13. The method of claim 1, wherein the intermetallic compound comprises an early transition metal selected from column 6 in the periodic table.

14. The method of claim 1, wherein the intermetallic compound comprises an element that is a late transition metal.

15. The method of claim 14, wherein the intermetallic compound comprises an element that is Ru, Rh, Os, Ir, or Pt.

16. The method of claim 1, wherein the intermetallic compound is AlTi_x.

17. The method of claim 16, wherein the workpiece further comprises a barrier layer that remains after removal of the first area.

18. The method of claim 1, wherein the workpiece is a microstructure comprising a silicon substrate.

19. The method of claim 18, wherein the first area comprises amorphous silicon;

and wherein the microstructure further comprises a structural layer and a barrier layer disposed between the structural layer and the first area.

20. The method of claim 18, further comprising:

removing the barrier layer disposed between the structural layer and the first area.

21. The method of claim 1, wherein the second area further comprises O or N.

22. The method of claim 21, wherein the O or N in the second area is 15 atomic % or less in weight.

23. The method of claim 21, wherein the O or N in the second area is 5% atomic or less in weight.

24. The method of claim 21, wherein O or N in the second area is in a form of TiO_x, TiN_x, AlO_x or AlN_x.

25. A method comprising:

forming a workpiece, comprising;

providing a substrate;

depositing a first and second sacrificial layer on the substrate; and

forming a first and second structural layers on the sacrificial layers, wherein the first and second structural layers comprises an intermetallic compound;

loading the workpiece to an etching chamber; and

removing at least a portion of the first and second sacrificial layers using a spontaneous vapor phase chemical etchant, wherein the chemical etchant comprises a chemical species that is selected from the group consisting of;

interhalogens and noble gas halides.

26. The method of claim 25, wherein the intermetallic compound comprises an early transition metal selected from column 4 in the periodic table.

27. The method of claim 25, wherein the intermetallic compound comprises an element that is Tc or Re.

28. The method of claim 25, wherein the intermetallic material is selected from the group consisting of Ni_xAl_y and TiNi.

29. The method of claim 25, wherein the intermetallic material is VAl_x, WTe_x, TiFe_x, TiPd_x, AlPd_x, MoPd_x, MoNi_x, MoFe_x, CoCr_x, CoMn_x, NiW_x, NiV_x, NiTi_xAl_y, NbAl_x, MoPd_x, AlCu_x, CuZn_x, or TaAl_x.

30. The method of claim 25, wherein the first or the second sacrificial layer comprises a material that is elemental metal, metalloid, metal alloy, metal silicide, W_xN or TaN_x.

31. The method of claim 25, wherein the workpiece is a micromirror array.

32. The method of claim 25, wherein the workpiece is a microelectromechanical device.

33. The method of claim 25, wherein the interhalogen comprises bromine trifluoride.

34. The method of claim 25, wherein the noble gas halide comprises xenon difluoride.

35. The method of claim 25, wherein vapor phase etchant further comprises a diluent gas that is a noble gas.

36. The method of claim 25, wherein the intermetallic compound comprises an early transition metal selected from column 5 in the periodic table.

37. The method of claim 25, wherein the intermetallic compound comprises an early transition metal selected from column 6 in the periodic table.

38. The method of claim 25, wherein the intermetallic compound comprises an element that is a late transition metal.

39. The method of claim 38, wherein the intermetallic compound comprises an element that is Ru, Rh, Os, Ir, or Pt.

40. The method of claim 25, wherein the intermetallic compound is AITi_x.

41. The method of claim 40, wherein the workpiece further comprises a barrier layer that remains after removal of the first and second sacrificial layers.

42. The method of claim 25, wherein the workpiece is a microstructure comprising a silicon substrate.

43. The method of claim 42, wherein the first or the second sacrificial layer comprises amorphous silicon;

and wherein the microstructure further comprises a barrier layer disposed between one of the first and second structural layers and one of the first and second sacrificial layers.

44. The method of claim 43, further comprising:

removing the barrier layer.

45. The method of claim 25, wherein the first or the second structural layer further comprises O or N.

46. The method of claim 45, wherein the O or N in the second area is 15 atomic % or less in weight.

47. The method of claim 45, wherein the O or N in the second area is 5 atomic % or less in weight.

48. The method of claim 45, wherein O or N in the second area is in a form of TiO_x, TiN_x, AlO_x or AlN_x.

49. A method for making a microstructure, the method comprising;

depositing a sacrificial material on a substrate, the sacrificial material comprising a metal;

depositing a structural layer after depositing the sacrificial material, wherein the structural layer comprises a material other than the sacrificial material, and wherein the material of the structural layer comprises an intermetallic compound; and

removing the sacrificial material with a spontaneous vapor phase chemical etchant, wherein the chemical etchant comprises a chemical species that is selected from the group consisting of;

interhalogens and noble gas halides.

50. The method of claim 49, wherein the sacrificial material comprises at least 25 percent in weight of said metal.

51. The method of claim 49, wherein the sacrificial material comprises at least 50 percent in weight of said metal.

52. The method of claim 49, wherein the sacrificial material comprises at least 90 percent in weight of said metal.

53. The method of claim 49, wherein the interhalogen comprises bromine trifluoride.

54. The method of claim 49, wherein the etchant is mixed with a diluent gas that is He, N₂, Ne, Ar, Ke, or Xe.

55. The method of claim 49, wherein the noble gas halide comprises xenon difluoride.

56. The method of claim 55, wherein the metal of the sacrificial material is a transition metal that is an early transition metal.

57. The method of claim 56, wherein the metal is a sputtered elemental metal material.