Adjustably transmissive MEMS-based devices

• US 8,054,527 B2
• Filed: 10/21/2008
• Issued: 11/08/2011
• Est. Priority Date: 10/23/2007
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Khazeni, Kasra, Gruhlke, Russell W., Xu, Gang, Mignard, Marc, Kothari, Manish
• Primary Examiner(s): Lester; Evelyn A.
• Application Number:
  US12/255,423
• Publication Number:
  US 20090103166A1
• Time in Patent Office: 1,113 Days
• Field of Search: 359/223, 359/224, 359290-292, 359/295, 359/298, 359/318
• US Class Current: 359/290
• 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
• CPC Class Codes: G02B 5/281 designed for the infrared light

Abstract

Modulator devices are selectably adjustable between at least two states, wherein the transmission and/or reflection of particular wavelengths of light are modified. Certain modulator devices are substantially uniformly adjustable over a wide range of wavelengths, including visible and infrared wavelengths. Other modulator devices are adjustable over visible wavelengths without significantly affecting infrared wavelengths. In addition, the modulator devices may be used in conjunction with fixed thin film reflective structures.

Claims

1. An electromechanical device, comprising:

a first film stack disposed upon a substrate, wherein the first thin film stack comprises a first titanium dioxide layer about 40 nm in thickness; and

a second film stack spaced apart from the first film stack by a gap, wherein the second film stack comprises a second titanium dioxide layer about 40 nm in thickness, wherein the second film stack is movable between a first position and a second position so as to alter the transmission of a wide range of visible wavelengths without significantly altering the transmission of infrared light.

2. The electromechanical device of claim 1, wherein the electromechanical device transmits at least about 50% more of the incident visible light when in said first position than in said second position.

3. The electromechanical device of claim 1, wherein the difference between the transmitted infrared light in the first position and the transmitted infrared light in the second position is no more than 10% of the incident infrared light.

4. The electromechanical device of claim 1, wherein the infrared light comprises infrared light having a wavelength of less than 1.5 microns.

5. The electromechanical device of claim 1, wherein the first thin film stack further comprises a first conductive layer, and wherein the second thin film stack further comprises a second conductive layer.

6. The electromechanical device of claim 5, wherein the first and second conductive layers comprise contiguous layers.

7. The electromechanical device of claim 5, wherein the first and second conductive layers comprise layers of indium tin oxide about 80 nm in thickness.

8. The electromechanical device of claim 1, additionally comprising a fixed thin film stack configured to reflect a substantial portion of incident light, wherein the fixed thin film stack is disposed between the first film stack and the substrate.

9. The electromechanical device of claim 8, wherein the fixed thin film stack is configured to reflect a substantial portion of incident infrared light.

10. The electromechanical device of claim 1, additionally comprising support structures located between said first thin film stack and said second thin film stack.

11. The electromechanical device of claim 10, wherein said support structures comprise glass spheres.

12. The electromechanical device of claim 1, wherein the MEMS device comprises at least one area wherein a portion of the second film stack is independently movable towards the first film stack.

13. The electromechanical device of claim 1, wherein the transmission of light is a first substantially uniform percentage across visible wavelengths when the second film stack is in said first position, and wherein the transmission of light is a second substantially uniform percentage across visible wavelengths when the second film stack is in said second position, said first percentage being different than said second percentage.

14. The electromechanical device of claim 1, wherein the electromechanical device comprises a second substrate extending substantially parallel to the first substrate on which the first film stack is disposed, wherein the second substrate comprises an additional fixed thin film stack disposed thereon.

15. The electromechanical device of claim 14, wherein the fixed thin film stack is configured to reflect a substantial portion of incident infrared light.

16. The electromechanical device of claim 15, wherein the thickness of the gap between the first and second thin film stacks is less than about 15 nm when the second film stack is in the second position.

17. The electromechanical device of claim 1, wherein the thickness of the gap between the first and second thin film stacks is about 170 nm when the second film stack is in the first position.

19. The electromechanical device of claim 15, wherein the electromechanical device transmits greater than about 80% of incident infrared light when in said first position and transmits less than about 55% of incident infrared light when in said second position.

18. An electromechanical device comprising:

a first film stack disposed upon a substrate, wherein the first film stack comprises a conductive layer and alternating sublayers of silicon oxide and titanium dioxide; and

a second film stack spaced apart from the first film stack by an air gap, wherein the second film stack comprises a conductive layer and alternating layers of silicon oxide and titanium dioxide, wherein the silicon dioxide sublayers in the first and second film stacks are about 20 nm in thickness and the titanium dioxide sublayers in the first and second film stacks are about 55 nm in thickness, and wherein the second film stack is movable between a first position and a second position so as to alter the transmission of a wide range of visible and infrared wavelengths;

wherein the electromechanical device transmits substantially more visible light and infrared light when in said first position than is transmitted in said second position.

20. The electromechanical device of claim 18, wherein the electromechanical device functions as a partially reflective broad band mirror which reflects roughly 20% of incident visible and infrared light when in said first position and reflects roughly 50% of incident visible and infrared light when in said second position.

21. The electromechanical device of claim 18, wherein the air gap is about between the first and second film stacks is about 180 nm when the device is in an unactuated position.

22. An electromechanical device comprising:

a first film stack disposed upon a substrate, wherein the first film stack comprises a layer of ITO;

a second film stack spaced apart from the first film stack by an air gap, wherein the second film stack is movable between a first position and a second position, and wherein the second film stack comprises a layer of ITO overlying a layer of titanium dioxide; and

a plurality of intermediate layers disposed between the first film stack and the second film stack, wherein the plurality of intermediate layers comprises a plurality of titanium dioxide layers;

wherein the electromechanical device transmits substantially more visible light and infrared light when in said first position than is transmitted in said second position.

23. The electromechanical device of claim 22, wherein the plurality of titanium dioxide layers are about 52 nm in thickness.

24. The electromechanical device of claim 22, wherein the layers of ITO are about 20 nm in thickness.