Film stack for manufacturing micro-electromechanical systems (MEMS) devices

• US 20060256420A1
• Filed: 03/31/2006
• Published: 11/16/2006
• Est. Priority Date: 06/24/2003
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Gally, Brian J., Chui, Clarence, Miles, Mark W.
• Granted Patent: US 7,616,369 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81C 1/00182 Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
• CPC Class Codes: B81C 1/0038 Processes for creating layers of materials not provided for in groups B81C1/00357 - B81C1/00373

Abstract

This invention provides a precursor film stack for use in the production of MEMS devices. The precursor film stack comprises a carrier substrate, a first layer formed on the carrier substrate, a second layer of an insulator material formed on the first layer, and a third layer of a sacrificial material formed on the second layer.

Claims

1. A film stack for the production of MEMS devices, the film stack comprising:

a substrate;

a first layer formed over the substrate;

a second layer formed over the first layer, said second layer comprising an insulator material; and

a third layer formed on the second layer, said third layer comprising a sacrificial material, wherein each of said first, second and third layers are formed prior to post-deposition processing of said layers.

2. The stack of claim 1, wherein the first, the second and the third layers are formed using a deposition technique.

3. The stack of claim 1, wherein the first layer comprises a conductive material comprising at least one of the following:

a single metal, a conductive oxide, a fluoride, a silicide, and a conductive polymer.

4. The stack of claim 1, wherein the first layer comprises at least one of the following:

Chromium, Tungsten, and Molybdenum.

5. The stack of claim 1, wherein the first layer comprises at least one of the following:

indium tin oxide (ITO), zinc oxide (ZnO), and titanium nitride (TiN).

6. The stack of claim 1, wherein the insulator material comprises at least one of the following:

an oxide, a polymer, a fluoride, a ceramic and a nitride.

7. The stack of claim 6, wherein the sacrificial material is etchable using a Xenon difluoride gas.

8. The stack of claim 1, wherein the sacrificial material is selected from the group comprising silicon, molybdenum, and tungsten.

9. The stack of claim 3, further comprising an optical compensation layer formed over the substrate, the optical compensation layer comprising a material of a finite extinction coefficient.

10. The stack of claim 9, wherein the optical compensation layer is formed over the first layer.

11. The stack of claim 9, wherein the optical compensation layer is formed under the first layer.

12. The stack of claim 9, wherein the optical compensation layer comprises a material comprising at least one of the following:

Zirconia and Hafnia.

13. The stack of claim 9, wherein the optical compensation layer comprises a material comprising at least one of the following:

an oxide, a nitride, and a fluoride.

14. The stack of claim 1, wherein the first layer comprises a plurality of sublayers, at least one of the sublayers comprising a conductive material.

15. The stack of claim 1, wherein at least one of the second layer and the third layer comprises a plurality of sublayers.

16. The stack of claim 1, wherein the sublayer furthest from the carrier substrate defines an optical layer.

17. The stack of claim 16, wherein the optical layer comprises a substantially non-conductive material.

18. The stack of claim 16, wherein the optical layer comprises a substantially conductive material.

19. The stack of claim 1, further comprising an optical layer deposited between the second and third layers.

20. The stack of claim 19, wherein the optical layer comprises a substantially non-conductive material.

21. The stack of claim 1, wherein the third layer comprises at least two sublayers, each sublayer alternating with the other, wherein each sublayer can be etched by the same release etchant, but has a different etch chemistry so that the sublayers define etch stops for each other.

22. The stack of claim 21, wherein the third layer comprises a sublayer of molybdenum that alternates with a sublayer of silicon.

23. A method of making a film stack for the production of MEMS devices, the method comprising:

providing a substrate;

forming a first layer over the substrate;

forming a second layer over the first layer, said second layer comprising an insulator material; and

forming a third layer over the second layer, said third layer comprising a sacrificial material, wherein forming each of said first, second and third layers is done prior to post-deposition processing of said layers.

24. The method of claim 23, wherein forming a first layer comprises forming a first layer comprising a conductive material comprising at least one of the following:

a single metal, a conductive oxide, a fluoride, a silicide, or a conductive polymer.

25. The method of claim 23, wherein the forming the first layer comprises forming a plurality of sublayers, at least one of the sublayers comprising a conductive material.

26. The method of claim 23, wherein forming at least one of the second and third layers comprises forming a plurality of sublayers, at least one of the sublayers comprising a conductive material.

27. The method of claim 25, wherein forming the sublayer furthest from the substrate comprises forming an optical layer.

28. The method of claim 27, wherein forming the optical layer comprises forming an optical layer comprising a substantially non-conductive material.

29. The method of claim 27, wherein forming the optical layer comprises forming an optical layer comprising a substantially conductive material.

30. The method of claim 23, further comprising depositing an optical layer between the second and third layers.

31. The method of claim 23, wherein forming the third layer comprises forming at least two sublayers, each sublayer alternating with the other to define etch stops for each other.

32. The method of claim 31, wherein forming the third layer comprises forming a sublayer of molybdenum that alternates with a sublayer of silicon.

33. The method of claim 24, further comprising forming an optical compensation layer over the substrate, the optical compensation layer comprising a material of a finite extinction coefficient.

34. The method of claim 33, wherein forming the optical compensation layer comprises forming the optical compensation layer over the first layer.

35. The method of claim 33, wherein forming the optical compensation layer comprises forming the optical compensation layer under the first layer.

36. The method of claim 33, wherein forming the optical compensation layer comprises forming an optical compensation layer comprising at least one of the following:

Zirconia and Hafnia.

37. The method of claim 33, wherein forming the optical compensation layer comprises forming an optical compensation layer comprising at least one of the following:

an oxide, a nitride, and a fluoride.

38. A film stack for the production of MEMS devices, the film stack comprising:

means for conducting an electrical current;

means for supporting said conducting means;

means for insulating said conducting means; and

means for defining the shape of an interferometric cavity above said conducting means.

39. The film stack of claim 38, wherein the supporting means comprises a substrate.

40. The film stack of claim 38, wherein the conducting means comprises a conductive material.

41. The film stack of claim 40, wherein the conducting means comprises a conductor stack.

42. The film stack of claim 38, wherein the insulating means comprises an insulator layer.

43. The film stack of claim 38, wherein the defining means comprises a sacrificial material layer.

44. The film stack of claim 38, additionally comprising means for selectively transmitting light.

45. The film stack of claim 44, wherein the selectively transmitting means comprises an optical compensation layer.