Active or self-biasing micro-bolometer infrared detector

• US 20030168599A1
• Filed: 01/24/2003
• Published: 09/11/2003
• Est. Priority Date: 07/25/2000
• Status: Active Grant

• Current Assignee: IR Sensors Pty., Ltd.
• Original Assignee: Kevin Liddiard
• Inventors: Liddiard, Kevin
• Granted Patent: US 6,927,392 B2
• Time in Patent Office: Days
• US Class Current: 250/338.1
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 31/02165 using interference filters, e.g. multilayer dielectric filters interference filters G02B5/28
• CPC Class Codes: H01L 31/09 Devices sensitive to infrared, visible or ultraviolet radiation H01L31/101 takes precedence

Abstract

The detector includes a thin-film resistive component (3), at least two first electrical contacts (6, 7) electrically connected to the resistive component (3) that provide for biasing and signal readout, at least one second electrical contact (1) electrically connected to the resistive component (3) that provides bias control, an integral infra-red absorption means (4, 5) and thermal isolation means (10, 11). The detector may further include a readout integrated microcircuit (RIOC).

Claims

1. An infrared radiation detector including:

a thin-film resistive component;

at least two first electrical contacts electrically connected to the resistive component so as to provide for biasing and signal readout;

at least one second electrical contact electrically connected to the resistive component so as to provide bias control;

an integral infrared absorption means; and

a thermal isolation means.

2. An infrared radiation detector as in claim 1 wherein said at least one second electrical contact is adapted to adjust the activation energy for electrical conduction in order to enhance the temperature coefficient of resistance of said resistive component.

3. An infrared radiation detector as in any one of the above claims wherein said detector functions in a self-amplification mode for the purpose of signal conditioning.

4. An infrared radiation detector as in any one of the above claims wherein said detector is located on a plane above or coplanar with a silicon wafer substrate.

5. An infrared radiation detector as in any one of the above claims wherein said detector further includes a readout integrated microcircuit (ROIC).

6. An infrared radiation detector as in any one of the above claims wherein the thin-film resistive component is formed in crystalline or amorphous silicon.

7. An infrared radiation detector as in any one of claims 1 to 5 wherein the thin-film resistive component is formed in alloys of silicon with material selected from the group consisting of hydrogen, nitrogen, germanium, boron, phosphorous, carbon, antimony, tin.

8. An infrared radiation detector as in any one of the above claims wherein said resistive component includes a dopant said dopant adjusting the electrical resistance of said resistive component.

9. An infrared radiation detector as in any one of the above claims wherein said dopant is formed from phosphorus or arsenic.

10. An infrared radiation detector as in any one of the above claims wherein said resistive component is a single film.

11. An infrared radiation detector as in any one of claims 1 to 10 wherein said resistive component is a composite film constructed of two or more layers each layer having different electrical conductivity.

12. An infrared radiation detector as in claim 11 wherein the conductivity of said layers is controlled by varying the amount of dopant or alloy concentration within the layers.

13. An infrared radiation detector as in any one of the above claims wherein said integral infrared absorption means includes a back reflector, said resistive component and a top metal layer arranged to form an integral optical interference filter.

14. An infrared radiation detector as in any one of the above claims wherein the thermal isolation means includes at least two legs raising said detector above the ground plane.

15. An infrared detector as in claim 14 wherein said legs are of a generally small cross-sectional area.

16. An infrared radiation detector as in any one of the above claims wherein the bias control modulates or adjusts the level of bias current operating in the detector.

17. An infrared radiation detector as in any one of claims 1 to 15 wherein the bias control switches the bias current in accordance with the signal readout requirements.

18. An infrared radiation detector as in any one of the above claims wherein the detector element is adaptable for electronic amplification of the detected signal.

19. A two-dimensional array of infrared detectors each detector including;

a thin-film resistive component;

at least two first electrical contacts electrically connected to the resistive component so as to provide for biasing and signal readout;

at least one second electrical contact electrically connected to the resistive component so as to provide bias control;

an integral infrared absorption means; and

a thermal isolation means.

20. A two-dimensional array of infrared detectors as in claim 19 wherein the bias control serves the function of removing fixed pattern noise from said two-dimensional array.

21. A two-dimensional array of infrared detectors as in claim 19 or claim 20 wherein an electronic circuit, which operates the bias control, is an external circuit or formed on a ROIC.

22. A two-dimensional array of infrared detectors as in any one of claims 19 to 21 each detector further including a memory component that stores bias values optionally as an external component or formed on the ROIC.

23. A two-dimensional array of infrared detectors as in any one of claims 19 to 22 wherein said detectors are adapted to function in a conventional passive mode without the bias control.

24. A method of producing an infrared radiation detector substantially as hereinbefore described.