Mm-wave/IR monolithically integrated focal plane array

• US 6,329,649 B1
• Filed: 10/07/1999
• Issued: 12/11/2001
• Est. Priority Date: 10/07/1998
• Status: Expired due to Term

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Balcerak, Ray, Dolezal, Franklin A., Jack, Michael D., Grinberg, Jan
• Primary Examiner(s): Dang, Hung Xuan
• Application Number:
  US09/414,988
• Time in Patent Office: 796 Days
• Field of Search: 250/250, 250/338.1, 250/336.1, 250/338.4, 250/339.02, 250/334, 250/370.01, 250/264, 250/266, 250/267, 338/14, 338/18, 338/22.R, 338/22.SD, 338/23, 338/24, 343/700, 343/720, 343/721
• US Class Current: 250/250
• CPC Class Codes: F41G 7/008 Combinations of different guidance systems
• CPC Class Codes: F41G 7/2286 using radio waves
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: G01J 5/34 using capacitors, e.g. pyroelectric capacitors
• CPC Class Codes: G01R 29/0878 Sensors; antennas; probes; detectors wave guide measuring sections G01R1/24
• CPC Class Codes: H01Q 21/0087 Apparatus or processes specially adapted for manufacturing antenna arrays manufacturing waveguides H01P11/00
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 3/2658 Phased-array fed focussing structure
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407

Abstract

An integrated infrared and millimeter-wave monolithic focal plane sensor array having a substrate upon which an integrated array of infrared sensors and mm-wave sensors are provided at a first planar level on the same side of the substrate, and a planar antenna for receiving incident millimeter-wave radiation located at a second planar level located between the integrated array of sensors and the surface of the substrates for coupling the mm-wave radiation field to the mm-wave sensor. The antenna receiver of electromagnetic radiation, in one embodiment, is an antenna having a crossed bowtie configuration which efficiently couples the radiation field to the mm-wave sensor. The invention also is directed to a method of fabricating such a radiation sensor.

Claims

1. An integrated infrared and millimeter-wave monolithic focal plane sensor array comprising:

a substrate having first and second opposing generally flat surfaces;

an array of infrared sensors and at least one millimeter-wave sensor provided at a first level on said first surface; and

a planar antenna for receiving incident millimeter-wave radiation located at a second level located between said first level and said first surface of the substrate, for coupling the millimeter-wave radiation field to the millimeter-wave sensor.

2. The focal plane sensor array according to claim 1 wherein the antenna comprises generally a crossed-bowtie shape.

3. The focal plane sensor array according to claim 2 wherein the crossed bowtie shape comprises first and second bowtie microantennas oriented orthogonally to each other, wherein each microantenna comprises first and second conductive arms separated by a lateral gap between inner ends of the arms, and where the inner ends underlap the millimeter-wave sensor in a manner whereby the antenna capacitively couples an incident radiation field to the millimeter-wave sensor.

4. The focal plane sensor array according to claim 2 where the antenna comprises a generally planar conductive metal film.

5. The focal plane sensor array according to claim 2 where the antenna comprises a generally planar aluminum film.

6. The focal plane sensor array according to claim 1 where the millimeter-wave sensor comprises a sandwich structure constructed of a thermoresistive film sandwiched between two dielectric layers and having a bottom conductive layer.

7. The focal plane sensor array according to claim 6 wherein the thermoresistive film comprises a vanadium oxide.

8. The focal plane sensor array according to claim 6 wherein the conductive layer comprises a metal.

9. The focal plane sensor array according to claim 8 wherein metal comprises nickel-chromium.

10. The focal plane sensor array according to claim 1 where the millimeter-wave sensor comprises a sandwich structure constructed of a thermoresistive film sandwiched between two dielectric layers and having a top conductive layer.

11. The focal plane sensor array according to claim 10 wherein the thermoresistive film comprises a vanadium oxide.

12. The focal plane sensor array according to claim 10 wherein the conductive layer comprises a metal.

13. The focal plane sensor array according to claim 1 where the millimeter-wave sensor comprises a sandwich structure constructed of a thermoresistive film sandwiched between two dielectric layers and having a top conductive layer and a bottom conductive layer.

14. The focal plane sensor array according to claim 13 wherein the thermoresistive film comprises a vanadium oxide.

15. The focal plane sensor array according to claim 13 wherein the conductive layers each comprises a metal.

16. The focal plane sensor array according to claim 1 where the substrate comprises a readout integrated circuit.

17. The focal plane sensor array according to claim 1 wherein said infrared sensors and said millimeter-sensor are bolometers.

18. The focal plane sensor array according to claim 1 where the infrared and millimeter-wave sensors comprise identical sandwich structures constructed of a thermosresistive film sandwiched between two dielectric layers and having at least one conductive layer absorbing the millimeter wave energy and a top layer absorbing the infrared wave energy.

19. An integrated infrared and millimeter-wave monolithic focal plane sensor array comprising:

a silicon wafer substrate having first and second opposing generally flat surfaces and a read-out integrated circuit,

an array of infrared sensors and at least one millimeter-wave sensor provided at a first planar level on said first surface, wherein the infrared sensors and millimeter-wave sensor are located above and physically spaced from the first surface of the substrate, and said IR sensors and millimeter-wave sensor each independently comprises (i) a sandwich structure comprising a heater metal film, a first dielectric film, a thermoresistive film, a second dielectric film, in that sequence, and (ii) at least one contact leg extending downward from and connecting the sandwich structure to the substrate; and

a planar antenna having a generally crossed-bowtie shape for receiving incident millimeter-wave radiation located at a second planar level located between and physically spaced from said first planar level and said first surface of the substrate, for coupling the millimeter-wave radiation field to the millimeter-wave sensor.

20. The focal plane sensor array according to claim 19 wherein the crossed bowtie shape comprises first and second bowtie microantennas oriented orthogonally to each other and out of contact with each other, wherein each microantenna comprises first and second conductive arms separated by a lateral gap between inner ends of the arms, and where the inner ends underlap the millimeter-wave sensor in a manner whereby the antenna capacitively couples an incident radiation field to the millimeter-wave sensor.

21. The focal plane sensor array according to claim 19 where the antenna comprises a generally planar conductive metal film.

22. The focal plane sensor array according to claim 19 where the antenna comprises a generally planar aluminum film.

23. The focal plane sensor array according to claim 19 wherein the thermoresistive film comprises a vanadium oxide.

24. The focal plane sensor array according to claim 19 wherein metal layer comprises nickel-chromium.

25. A method for making a radiation sensor, comprising the steps of:

providing a substrate having first and second opposing surfaces;

forming a generally planar thin film antenna on an insulating layer on the first surface of the substrate;

depositing a temporary sacrificial layer having an upper horizontally-extending surface and side vertically-extending surfaces on the antenna;

forming an array of infrared sensors and at least one millimeter-wave sensor each having a planar sandwich structure and as located above and physically spaced from the antenna due to the intervening sacrificial layer material by sequentially forming, in this order, a heater metal layer, a first dielectric film, a thermoresistive film, and a second dielectric film, on the sacrificial layer;

forming conductive contact legs in contact with the thermoresistive film and continuing along the side surfaces of the sacrificial layer such that the legs extend downward from and connect the sandwich structures of the sensors to the substrate; and

selectively removing the sacrificial layer to form an air gap between the antenna and the heater metal film of the millimeter-wave sensor.

26. The method of claim 25 wherein the sacrificial layer comprises a photoresist.

27. The method of claim 25 wherein thermoresistive film is provided as vanadium oxide, the heater metal layer is provided as nickel-chromium, and the antenna is provided as aluminum.