Infrared detector array with an elevated thin film

• US 5,959,298 A
• Filed: 06/14/1996
• Issued: 09/28/1999
• Est. Priority Date: 04/04/1994
• Status: Expired due to Fees

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Owen, Robert A., Belcher, James F.
• Primary Examiner(s): Porta, David P.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US08/665,135
• Time in Patent Office: 1,201 Days
• Field of Search: 250/338.3, 250/332, 250/338.1, 250/338.2, 257/448
• US Class Current: 250/338.3
• CPC Class Codes: H01L 27/1465 of the hybrid type
• CPC Class Codes: H10N 15/10 Thermoelectric devices using thermal change of the dielectric constant, e.g. working above and below the Curie point

Abstract

A novel reticulated array comprises islands of ceramic (e.g. BST 40) which are fabricated from novel materials using unique methods of patterning. A shallow etch stop trench (46) is first ion milled around each ceramic island on front side and then filled with an etch stop material (e.g. parylene 48). An optical coat (e.g transparent metal layer 54, transparent organic layer 56 and conductive metallic layer 58) is elevated above the etch stop material by an elevation layer (e.g. polyimide 49). For some applications, it has been experimentally verified that there is no loss, and sometimes a measured increase, in optical efficiency when the optical coating is not planar in topology. Novel fabrication methods also provide for the convenient electrical and mechanical bonding of each of the massive number of ceramic islands to a signal processor substrate (e.g. Si 86) containing a massive array of sensing circuits.

Claims

1. A microelectronic infrared detector array comprising:

a reticulated array of ceramic islands;

an optical coating layer disposed on said ceramic islands, wherein said optical coating layer comprises elevated portions between said ceramic islands, whereby said elevated portions of said optical coating layer provide improved thermal efficiency for sensing impinging infrared radiation; and

electrical contacts disposed on a surface of said ceramic islands opposite said optical coating layer.

2. The detector array of claim 1, wherein said ceramic islands comprise a first cross-sectional area proximate said optical coating layer which is larger than a second cross-sectional area proximate said electrical contacts.

3. The detector array of claim 1, wherein said ceramic islands comprise barium strontium titanate.

4. The detector array of claim 1, further comprising a reticulated protective metal layer disposed between said ceramic islands and said optical coating layer.

5. The detector array of claim 4, wherein said protective metal layer is TiW.

6. The detector array of claim 1, wherein said elevated portions of said optical coating layer partially overlap said ceramic islands.

7. The detector array of claim 1, wherein said optical coating layer comprises:

a conductive metallic layer adjacent said ceramic islands;

a transparent organic layer disposed on said conductive metallic layer; and

a thin transparent metal layer disposed on said transparent organic layer.

8. the detector array of claim 7, wherein said conductive metallic layer is NiCr, said transparent organic layer is parylene, and said thin transparent metal layer is NiCr.

9. The detector array of claim 1, wherein said array comprises infrared-sensitive capacitors.

10. The detector array of claim 1, wherein said electrical contacts each comprise two or more layers.

11. The detector array of claim 1, wherein said electrical contacts comprise indium.

12. The detector array of claim 1, wherein said electrical contacts are bonded to a signal processing substrate.

13. A microelectronic infrared detector array comprising:

a reticulated array of ceramic islands;

an optical coating layer disposed on said ceramic islands, wherein said optical coating layer comprises elevated portions between partially overlapping said ceramic islands;

electrical contacts disposed on a surface of said ceramic islands opposite said optical coating layer; and

a signal processing substrate bonded to said electrical contacts.

14. The detector array of claim 13, wherein said ceramic islands comprise a first cross-sectional area proximate said optical coating layer which is larger than a second cross-sectional area proximate said electrical contacts.

15. The detector array of claim 13, wherein said ceramic islands comprise barium strontium titanate.

16. The detector array of claim 13, further comprising a reticulated protective metal layer disposed between said ceramic islands and said optical coating layer.

17. The detector array of claim 13, wherein said optical coating layer comprises:

a conductive metallic layer adjacent said ceramic islands;

a transparent organic layer disposed on said conductive metallic layer; and

a thin transparent metal layer disposed on said transparent organic layer.

18. The detector array of claim 13, wherein said array comprises infrared-sensitive capacitors.

19. The detector array of claim 13, wherein said electrical contacts each comprise two or more layers.

20. The detector array of claim 13, wherein said electrical contacts comprise indium.