Multi-spectral uncooled microbolometer detectors

• US 7,491,938 B2
• Filed: 03/23/2005
• Issued: 02/17/2009
• Est. Priority Date: 03/23/2004
• Status: Expired due to Fees

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Kohin, Margaret, Geneczko, Jeannie, Blackwell, Richard
• Primary Examiner(s): Hannaher; Constantine
• Application Number:
  US10/589,525
• Publication Number:
  US 20070176104A1
• Time in Patent Office: 1,427 Days
• Field of Search: None
• US Class Current: 250/339.02
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 27/14669 Infrared imagers
• CPC Class Codes: H01L 31/09 Devices sensitive to infrared, visible or ultraviolet radiation H01L31/101 takes precedence

Abstract

A process and system for a medium wave infrared (MWIR) uncooled microbolometer focal plane array (FPA). One embodiment is for a single MWIR band uncooled IR detector, wherein the design and fabrication utilizes standard silicon processing techniques reducing manufacturing costs and preserving existing manufacturing capabilities. Another embodiment is a two color uncooled microbolometer IR detector providing broadband detection.

Claims

1. A multi-band infrared imaging device, comprising:

in a single microbridge level, an uncooled microbolometer focal plane array comprising at least plurality of pixels, each of said pixels farther comprising at least one structure layer, a detector layer and a medium wave absorber layer, and wherein each said pixel simultaneously detects at least two IR bands.

2. The device according to claim 1, wherein said array is fabricated by LWIR processing.

3. The device according to claim 1, wherein said bands are selected from the group consisting of:

MWIR/LWIR, MWIR/SWIR, SWIR/LWIR, and SWIR/MWIR/LWIR.

4. The device according to claim 1, wherein said structure layer is selected from at least one of the group consisting of:

metal films, semiconductor films, and dielectrics.

5. The device according to claim 1, wherein said medium wave absorber layer is selected from at least one of the group consisting of:

metal films, semiconductor films, and dielectrics with high MW absorption.

6. An optical stack for an uncooled microbolometer device, comprising:

in a single microbridge level, a read out integrated circuit (ROIC) substrate;

a reflector on a surface of said substrate;

a plurality of layers fabricated by LWIR processing, wherein said plurality of layers include an MWIR absorber, a detector, and at least one structure layer providing support and/or isolation;

a gap between said reflector and said plurality of layers; and

wherein said stack is part of said uncooled microbolometer and detects at least medium wave radiation.

7. The stack according to claim 6, wherein said structure layer is selected from at least one of the group consisting of:

metal films, semiconductor films, and dielectrics.

8. The stack according to claim 6, wherein said stack further detects LWIR and/or SWIR.

9. The stack according to claim 6, wherein said structure layer comprises at least one silicon nitride layer and at least one silicon dioxide layer.

10. The stack according to claim 6, wherein said detector is vanadium oxide (VOx) or amorphous silicon.

11. The stack according to claim 6, wherein said MWIR absorber is selected from at least one member of the group consisting of:

metal films, semiconductor films, and dielectrics with high MW absorption.

12. The stack according to claim 11, wherein said MWIR absorber is chrome, titanium nitride (TiN) or titanium tungsten (TiW).

13. A multi-spectral infrared (IR) focal plane array, comprising:

in a single microbridge level, an uncooled microbolometer detecting at least two infrared bands, said microbolometer comprising;

a generally planar read out integrated circuit substrate base;

at least one generally planar microbridge disposed approximately parallel to said base and separated by a gap; and

wherein each said microbridge comprises a plurality of layers, said layers comprising at least one structural support layer, a detector layer, and selectively a medium wave absorber layer.

14. The array according to claim 13, wherein said array is selectively programmable to at least one of said bands.

15. The array according to claim 13, wherein said array is processed by LWIR techniques.

16. The array according to claim 13, wherein said at least one microbridge forms a two-dimensional array having at least one microbridge without said medium wave absorber layer.

17. The array according to claim 13, wherein said multiple IR bands are selected from the group consisting of:

SWIR/MWIR, SWIR/LWIR, MWIR/LWIR, and SWIR/MWIR/LWIR.

18. The device according to claim 13, wherein each said microbridge of said array is arranged in a pattern having at least one said microbridge with said medium wave absorber and least one said microbridge without said medium wave absorber.

19. The array according to claim 13, wherein said medium wave absorber is selectively formed by a pattern etch.

20. The array according to claim 13, wherein at least one microbridge of the array is optimized for one of said bands and at least one microbridge of the array is optimized for one of said bands and at least one microbridge of the array is optimized for a different one of said bands.