Uncooled infrared detector and method for forming the same

• US 5,367,167 A
• Filed: 08/16/1993
• Issued: 11/22/1994
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Keenan, William F.
• Primary Examiner(s): FIELDS, CAROLYN
• Application Number:
  US08/107,398
• Time in Patent Office: 463 Days
• Field of Search: 250/352, 250/338.1, 250/349, 250/332, 250/338.4, 250/370.06, 250/370.08
• US Class Current: 250/338.4
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 27/1467 of the hybrid type
• CPC Class Codes: H04N 23/20 for generating image signals from infrared radiation only
• CPC Class Codes: H04N 25/60 Noise processing, e.g. detecting, correcting, reducing or removing noise
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

A bolometer for detecting radiation in a spectral range is described herein. The bolometer includes an integrated circuit substrate 122 and a pixel body 120 spaced from the substrate 122 by at least one pillar 124. The pixel body 120 comprises an absorber material 132, such as titanium for example, for absorbing radiation in the spectral range, which may be 7 to 12 microns for example. The absorber material 132 heats the pixel body 120 to a temperature which is proportional to the absorbed radiation. An insulating material 134 is formed over the absorber material 132. In addition, a variable resistor material 136, possible amorphous silicon for example, with an electrical resistance corresponding to the temperature of the pixel body 120 is formed over said insulating layer 134. A current flows through the variable resistor material 136 substantially parallel to the integrated circuit substrate 122 for detection. Other systems and methods are also disclosed.

Claims

1. A bolometer for detecting radiation in a spectral range comprising:

an integrated circuit substrate; and

a pixel body spaced from said substrate by at least one pillar, said pixel body comprising;

an absorber material for absorbing radiation in said spectral range, said absorber material heating said pixel body to a temperature in proportion to the absorbed radiation;

an insulating material formed over said absorber material; and

a variable resistor material with an electrical resistance corresponding to the temperature of said pixel body, said variable resistor material formed over said insulating material.

2. The bolometer of claim 1 wherein said spectral range is between 7 and 12 microns.

3. The bolometer of claim 1 wherein said pixel body is spaced between about 2 and 3 microns from said integrated circuit substrate.

4. The bolometer of claim 1 and further comprising a passivation layer formed beneath said absorber material.

5. The bolometer of claim 4 wherein said passivation layer comprises silicon oxide.

6. The bolometer of claim 1 wherein said absorber material is titanium.

7. The bolometer of claim 1 wherein said variable resistor material is amorphous silicon.

8. The bolometer of claim 1 wherein said insulating material comprises amorphous silicon.

9. The bolometer of claim 1 wherein said insulating material comprises silicon dioxide.

10. The bolometer of claim 9 wherein said passivation layer comprises silicon dioxide.

11. The bolometer of claim 1 wherein said insulating material comprises silicon nitride.

12. The bolometer of claim 1 and further comprising a mirror region formed on said substrate beneath said pixel body.

13. The bolometer of claim 12 wherein said mirror region comprises aluminum.

14. The bolometer of claim 1 wherein said variable resistor includes a resistor path region, said resistor path region substantially parallel to said integrated circuit substrate.

15. An infrared detection array comprising:

an array of bolometers, each of said bolometers comprising;

an integrated circuit substrate; and

a pixel body spaced from said substrate by at least one pillar, said pixel body comprising;

an absorber material for absorbing radiation in a selected spectral range, said absorber material heating said pixel body to a temperature in proportion to the absorbed radiation;

an insulating material formed over said absorber material; and

a variable resistor material with an electrical resistance corresponding to the temperature of said pixel body, said variable resistor material formed over said insulating material; and

circuitry formed in said substrate for detecting changes in said resistance of said variable resistor material.

16. The array of claim 15 wherein said spectral range is between about 7 and 12 microns.

17. The array of claim 15 wherein said absorber material is titanium.

18. The array of claim 15 wherein said variable resistor material is amorphous silicon.

19. The array of claim 15 wherein said insulating material comprises amorphous silicon.

20. The array of claim 15 wherein each of said bolometers further comprise a passivation layer formed beneath said absorber material.

21. The array of claim 20 wherein said passivation layer comprises silicon dioxide.

22. The array of claim 15 wherein said variable resistor includes a resistor path region, said resistor path region substantially parallel to said integrated circuit substrate.