Electromagnetic radiation detectors having a microelectromechanical shutter device

• US 20040046123A1
• Filed: 05/29/2003
• Published: 03/11/2004
• Est. Priority Date: 04/13/2001
• Status: Active Grant

• Current Assignee: MCNC, Inc., Micross Advanced Interconnect Technology LLC
• Original Assignee: MCNC Research & Development Institute (Research Triangle Institute)
• Inventors: Dausch, David E.
• Granted Patent: US 7,026,602 B2
• Time in Patent Office: Days
• US Class Current: 250/351
• CPC Class Codes: B81B 3/0035 Constitution or structural means for controlling the movement of the flexible or deformable elements
• CPC Class Codes: G02B 26/04 by periodically varying the intensity of light, e.g. using choppers shutters, diaphragms for cameras G03B9/00; devices for eliminating or reducing the effect of flicker in projection systems G03B21/40
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/0866 the reflecting means being moved or deformed by thermal means

Abstract

The present invention provides for an improved electromagnetic radiation detector having a micromachined electrostatic chopper/shutter device. The MEMS flexible film chopper/shutter device provides reliability, efficiency, noise reduction and temperature fluctuation compensation capabilities to the associated electromagnetic radiation detector. An electromagnetic radiation detector having an electrostatic chopper/shutter device includes a detector material element and flexible film actuator overlying the detector material layer and moveable relative thereto. The flexible film actuator will typically include an electrode element and a biasing element such that the actuator remains in a fully curled, open state absent electrostatic voltage and moves to a fully uncurled, closed state upon the application of electrostatic voltage. Arrays that incorporate a plurality of electromagnetic radiation detectors and/or electrostatic shuttering devices are additionally provided for.

Claims

1. An electromagnetic radiation detector device having an electrostatically driven microelectromechanical system (MEMS) shutter, comprising:

a photo-detector element; and

a flexible film actuator overlying said photo-detector element and moveable relative thereto to alternately allow passage of electromagnetic radiation to said photo-detector material element and block passage of radiation to said photo-detector material element.

2. The device of claim 1, further comprising a transparent substrate that supports the detector element and is disposed between the flexible film actuator and the photo-detector element.

3. The device of claim 1, wherein the flexible film actuator further comprises an electrode element and a biasing element, the actuator having a fixed portion attached to an underlying surface and a distal portion moveable relative to an underlying transparent electrode disposed between the flexible film actuator and the photo-detector element.

4. The device of claim 3, further comprising a transparent dielectric element disposed between the electrode element and the underlying transparent electrode.

5. The device of claim 1, further comprising an anti-reflection element disposed between the photo-detector element and the flexible film actuator.

6. The device of claim 1, wherein the photo-detector element is further defined as a photovoltaic detector element.

7. The device of claim 1, wherein the photo-detector element is further defined as a photoconductive detector element.

8. The device of claim 1, wherein the photo-detector element is further defined as a quantum well infrared photodetector element.

9. The device of claim 1, wherein the photo-detector element further comprises a semiconductor material having a doped region.

10. The device of claim 9, wherein the semiconductor material is chosen from the group consisting of, silicon, germanium, mercury-cadmium-tellurium (HgCdTe), indium antimonide (InSb), III-V compound semiconductors and II-V compound semiconductors.

11. An electromagnetic radiation detector device having an electrostatically driven MEMS shutter, the device comprising:

a first transparent substrate;

a flexible film actuator disposed on the first transparent substrate;

a second transparent substrate;

a photo-detector element disposed on the second transparent substrate; and

one or more solder bumps that serve to connect the first transparent substrate to the second transparent substrate.

12. The device of claim 11, wherein the flexible film actuator further comprises a flexible electrode element and a biasing element, the actuator having a fixed portion attached to an underlying surface and a distal portion moveable relative to an underlying fixed transparent electrode disposed between the flexible film actuator and the first transparent substrate.

13. The device of claim 12, further comprising a transparent dielectric element disposed between the flexible electrode element and the underlying fixed transparent electrode.

14. The device of claim 11, further comprising an anti-reflection element disposed between the photo-detector element and the flexible film actuator.

15. The device of claim 11, wherein the photo-detector element is further defined as a photovoltaic detector element.

16. The device of claim 11, wherein the photo-detector element is further defined as a photoconductive detector element.

17. The device of claim 11, wherein the photo-detector element is further defined as a quantum well infrared photo-detector element.

18. The device of claim 11, wherein the photo-detector element further comprises a semiconductor material having a doped region.

19. The device of claim 18, wherein the semiconductor material is chosen from the group consisting of, silicon, germanium, mercury-cadmium-tellurium (HgCdTe), indium antimonide (InSb), III-V compound semiconductors and II-V compound semiconductors

20. An electromagnetic radiation detector array having an electrostatically driven microelectromechanical system (MEMS) shutter array, comprising:

a substrate;

a plurality of detector pixels supported by said substrate, said detector pixels comprising;

a photo-detector element; and

a flexible film actuator overlying said photo-detector element and moveable relative thereto to alternately allow passage of electromagnetic radiation to said photo-detector material element and block passage of radiation to said photo-detector material element.

21. The detector array of claim 20, wherein the substrate further comprises a silicon substrate having a read-out circuit disposed thereon.

22. The detector array of claim 20, wherein the plurality of flexible film actuators further comprise a flexible electrode and a biasing element, each actuator having a fixed portion attached to an underlying surface and a distal portion moveable relative to a transparent electrode of the corresponding detector pixel.

23. The detector array of claim 20, wherein the photo-detector layer is further defined as a photovoltaic detector layer.

24. The detector array of claim 20, wherein the photo-detector layer is further defined as a photoconductive detector layer.

25. The detector array of claim 20, wherein the photo-detector layer is further defined as a quantum well infrared photo-detector layer.

26. The detector array of claim 20, wherein the photo-detector layer further comprises a semiconductor material having a doped region.

27. The detector layer of claim 20, wherein the semiconductor material is chosen from the group consisting of silicon, germanium, mercury-cadmium-tellurium (HgCdTe), III-V compound semiconductors and II-V compound semiconductors.

28. A method for pixel modulation in an electromagnetic radiation detector array, the method comprising:

providing for a plurality of electrostatically activated flexible film actuators, each actuator corresponding to one or more photo-detector pixels in an electromagnetic radiation detector array;

shuttering one or more flexible film actuators to allow passage of electromagnetic radiation to the one or more photo-detector pixels corresponding to the flexible film actuator;

detecting photons in the one or more photo-detector pixels as a result of the shuttering of the corresponding flexible film actuator;

generating charge carriers in the one or more photo-detector pixels in response to the detection of photons; and

generating a read-out signal as a result of the charge carriers in the one or more detector pixels.

29. The method of claim 28, wherein the step of shuttering one or more flexible film actuators to allow passage of electromagnetic radiation to the one or more photo-detector pixels corresponding to the flexible film actuator further comprises:

deactivating, by releasing the electrostatic force, one or more flexible film actuators to allow passage of electromagnetic radiation to the corresponding one or more photo-detector pixels.

30. The method of claim 28, wherein the step of generating a read-out signal as a result of charge carriers in the one or more detector pixels further comprises generating a read-out voltage signal.

31. The method of claim 28, wherein the step of generating a read-out signal as a result of the charge carriers in the one or more detector pixels further comprises generating a read-out current value.

32. The method of claim 28, wherein shuttering of the one or more flexible film actuators provides intermittent open (on) or blocked (off) states in the one of more photo-detector pixels.

33. The method of claim 28, wherein shuttering of the one or more flexible film actuators provides chopping of the incident electromagnetic radiation at a continuous frequency to the one or more photo-detector pixels.