Electrical conditioning of MEMS device and insulating layer thereof

• US 20070196944A1
• Filed: 02/22/2006
• Published: 08/23/2007
• Est. Priority Date: 02/22/2006
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Chou, Chen-Jean, Wu, Chun-chen, Brinkley, Patrick
• Granted Patent: US 7,547,568 B2
• Time in Patent Office: Days
• US Class Current: 438/48
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81C 1/00714 Treatment for improving the physical properties not provided for in groups B81C1/0065 - B81C1/00706
• CPC Class Codes: B81C 2201/0107 Sacrificial metal
• CPC Class Codes: B81C 99/004 during manufacturing
• 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

A method of fabricating a MEMS device includes conditioning of an insulating layer by applying a voltage across the insulating layer via a conductive sacrificial layer for a period of time, prior to removal of the conductive sacrificial layer. This conditioning process may be used to saturate or stabilize charge accumulated within the insulating layer. The resistance across the insulating layer may also be measured to detect possible defects in the insulating layer.

Claims

1. A method of making a MEMS device, comprising:

forming a first electrode layer;

forming a dielectric layer over the first electrode layer;

depositing a layer of sacrificial material over the dielectric layer, wherein the layer of sacrificial material is conductive, and wherein the layer of sacrificial material is in electrical communication with the dielectric layer; and

applying a voltage to said layer of sacrificial material.

2. The method of claim 1, additionally comprising forming a second electrode layer over said layer of sacrificial material.

3. The method of claim 2, additionally comprising patterning said second electrode layer to expose at least one portion of the layer of sacrificial material, wherein the voltage is applied to said at least one exposed portion.

4. The method of claim 3, wherein patterning said second electrode layer comprises forming an aperture in said second electrode layer.

5. The method of claim 3, additionally comprising patterning said layer of sacrificial material to form a contact area, wherein the voltage is applied to said contact area.

6. The method of claim 2, additionally comprising forming a partially reflective layer between the first electrode layer and the dielectric layer.

7. The method of claim 2, wherein forming the second electrode layer comprises forming a reflective layer adjacent the layer of sacrificial material.

8. The method of claim 7, wherein forming the second electrode layer comprises forming a deformable layer above the layer of sacrificial material.

9. The method of claim 1, wherein the voltage is applied for a period of time sufficient to stabilize the charge in the dielectric layer.

10. The method of claim 1, wherein the voltage is applied for at least about 5 minutes.

11. The method of claim 1, wherein the voltage is applied for at least about 10 minutes.

12. The method of claim 1, additionally comprising forming at least one conductive lead in electrical communication with the first electrode layer, wherein the voltage is applied to said at least one conductive lead.

13. The method of claim 1, wherein the dielectric layer comprises silicon oxide.

14. The method of claim 1, wherein the dielectric layer comprises silicon nitride.

15. The method of claim 1, wherein the layer of sacrificial material comprises molybdenum.

16. A MEMS device fabricated by the method of claim 1.

17. The MEMS device of claim 16, wherein the MEMS device comprises at least one interferometric modulator.

18. The MEMS device of claim 17, further comprising:

a processor that is configured to communicate with at least said first electrode layer, said processor being configured to process image data;

a memory device that is configured to communicate with said processor.

19. The MEMS device of claim 18, further comprising a driver circuit configured to send at least one signal to at least said first electrode layer.

20. The MEMS device of claim 19, further comprising a controller configured to send at least a portion of said image data to said driver circuit.

21. The MEMS device of claim 18, further comprising an image source module configured to send said image data to said processor.

22. The MEMS device of claim 21, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

23. The MEMS device of claim 18, further comprising an input device configured to receive input data and to communicate said input data to said processor.

24. A method of testing a partially fabricated MEMS device, comprising:

applying a voltage between a conductive sacrificial layer and a first electrode layer, wherein a dielectric layer is located between said sacrificial layer and said first electrode layer; and

measuring the resistance across at least the conductive sacrificial layer, the first electrode layer, and any intervening layers.

25. The method of claim 24, additionally comprising identifying the MEMS device as defective if the resistance is below a predetermined value.

26. The method of claim 25, wherein the MEMS device is identified as defective if the resistance is less than about 100 kΩ

.

27. The method of claim 26, wherein the MEMS device is identified as defective if the resistance is less than about 10 kΩ

.

28. A system for conditioning a partially fabricated MEMS device, the system comprising:

a substrate;

a first electrode layer located over the substrate;

a dielectric layer located over the first electrode layer;

a conductive sacrificial layer located over the dielectric layer; and

a power source in electrical communication with the conductive sacrificial layer.

29. The system of claim 28, additionally comprising a second electrode layer located over the dielectric layer, wherein the second conductive layer has been patterned to expose a portion of the underlying sacrificial layer, and wherein said power source is in electrical communication with the exposed portion of the conductive sacrificial layer.

30. A method of fabricating a MEMS device, comprising:

providing a first electrode layer;

providing a dielectric layer located over the first electrode layer;

providing a conductive sacrificial layer located over the dielectric layer;

providing a second electrode layer located over the conductive sacrificial layer;

applying a voltage to the conductive sacrificial layer for a period of time; and

etching the conductive sacrificial material to define a cavity.

31. The method of claim 30, further comprising providing a partially reflective layer located between the first electrode layer and the dielectric layer, and wherein the second electrode layer comprises a reflective layer.

32. The method of claim 30, wherein the conductive sacrificial layer comprises molybdenum.

33. The method of claim 30, wherein etching the conductive sacrificial comprises a XeF₂ etch.

34. The method of claim 30, wherein the dielectric layer comprises at least one of silicon oxide and silicon nitride.