DIFFUSION BARRIER LAYER FOR MEMS DEVICES

• US 20100046058A1
• Filed: 11/06/2009
• Published: 02/25/2010
• Est. Priority Date: 10/28/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Wang, Hsin-Fu, Zee, Stephen, Tung, Ming-Hau
• Granted Patent: US 8,085,458 B2
• Time in Patent Office: Days
• US Class Current: 359/237
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 3/0072 For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
• CPC Class Codes: B81C 1/00793 Avoid contamination, e.g. absorption of impurities or oxidation
• CPC Class Codes: B81C 2201/0167 by adding further layers of materials having complementary strains, i.e. compressive or tensile strain
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26

Abstract

Described herein is the use of a diffusion barrier layer between metallic layers in MEMS devices. The diffusion barrier layer prevents mixing of the two metals, which can alter desired physical characteristics and complicate processing. In one example, the diffusion barrier layer may be used as part of a movable reflective structure in interferometric modulators.

Claims

1. A method of substantially inhibiting any portion of a first metallic layer from mixing with any portion of a second metallic layer in a MEMS device mechanical membrane, comprising positioning a diffusion barrier layer between the first and second metallic layers.

2. The method of claim 1, wherein the first metallic layer comprises aluminum.

3. The method of claim 1, wherein the second metallic layer comprises chromium.

4. The method of claim 1, wherein the diffusion barrier layer comprises an oxide, nitride, or carbide.

5. The method of claim 1, wherein the diffusion barrier layer comprises silicon dioxide.

6. The method of claim 1, wherein the MEMS device is an interferometric modulator and the first metallic layer acts as a mirror in the mechanical membrane.

7. The method of claim 1, wherein the positioning of the diffusion barrier layer comprises:

depositing the diffusion barrier layer onto the first metallic layer; and

depositing the second metallic layer onto the diffusion barrier layer.

8. The method of claim 7, wherein the deposition of the diffusion barrier layer is conducted using physical vapor deposition, chemical vapor deposition, or sol gel processing.

9. A method of manufacturing a MEMS device, comprising:

depositing a first metallic layer;

depositing a diffusion barrier layer onto the first metallic layer;

depositing a second metallic layer onto the diffusion barrier layer, wherein the diffusion barrier layer is adapted to substantially inhibit any portion of the first metallic layer from mixing with any portion of the second metallic layer; and

etching a same pattern in the first metallic layer, diffusion barrier layer, and second metallic layer.

10. The method of claim 9, wherein the first metallic layer comprises aluminum.

11. The method of claim 9, wherein the second metallic layer comprises chromium.

12. The method of claim 9, wherein the diffusion barrier layer comprises an oxide, nitride, or carbide.

13. The method of claim 9, wherein the diffusion barrier layer comprises silicon dioxide.

14. The method of claim 9, wherein etching a same pattern comprises employing different etchants for each of the first metallic layer, diffusion barrier layer, and second metallic layer.

15. A MEMS device, comprising a mechanical membrane produced by the process of claim 9.

16. A method of manufacturing an interferometric modulator, comprising:

depositing a first metallic layer;

depositing a diffusion barrier layer onto the first metallic layer;

depositing a second metallic layer onto the diffusion barrier layer, wherein the diffusion barrier layer is adapted to substantially inhibit any portion of the first metallic layer from mixing with any portion of the second metallic layer; and

etching a same pattern in the second metallic layer, the diffusion barrier, and the first metallic layer.

17. The method of claim 16, wherein etching the pattern in the second metallic layer comprises using a first etchant, etching the pattern in the diffusion barrier comprises using a second etchant, and etching the pattern in the first metallic layer comprises using a third etchant.

18. The method of claim 16, wherein the diffusion barrier layer comprises an oxide, nitride, or carbide.

19. The method of claim 16, wherein the diffusion barrier layer comprises silicon dioxide.

20. The method of claim 17, wherein the diffusion barrier layer and the first metallic layer is substantially resistant to the first etchant.

21. The method of claim 17, wherein the first metallic layer the second metallic layer is substantially resistant to the second etchant.

22. The method of claim 17, wherein the diffusion barrier layer and the second metallic layer is substantially resistant to the third etchant.

23. The method of claim 17, wherein the first etchant is CR14.

24. The method of claim 17, wherein the second etchant is PAD.

25. The method of claim 17, wherein the third etchant is PAN.

26. An interferometric modulator produced by the process of claim 16.

27. A method of manufacturing a movable electrode in a MEMS device having a desired tensile stress, comprising:

determining a desired tensile stress or range of tensile stress for the movable electrode;

forming one or more layers comprising a material having tensile stress; and

forming one or more layers comprising a material having compressive stress adjacent to the tensile stress materials, whereby combination of the tensile stress of the compressive stress provide the desired tensile stress or range of tensile stress for the movable electrode.

28. The method of claim 27, wherein the material of the tensile stress layers is one or more metal(s).

29. The method of claim 28, wherein the metal is selected from the group consisting of aluminum, chromium, titanium, copper, iron, silicon, manganese, magnesium, lithium, silver, gold, nickel, tantalum, and tungsten.

30. The method of claim 27, wherein the compressive stress layers is one or more oxide, nitride, or carbide.

31. The method of claim 27, wherein at least one compressive stress layer comprises silicon dioxide.

32. A MEMS device movable electrode produced by the process of claim 27.