Infrared focal plane array

• US 6,031,231 A
• Filed: 09/10/1997
• Issued: 02/29/2000
• Est. Priority Date: 01/27/1997
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Hata, Hisatoshi, Ishikawa, Tomohiro, Kimata, Masafumi, Tsutsumi, Kazuhiko
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Gagliardi, Albert
• Application Number:
  US08/927,407
• Time in Patent Office: 902 Days
• Field of Search: 250/332, 250/338.1, 250/338.3, 250/338.4, 250/339.01, 250/339.02, 250/339.04, 250/370.08
• US Class Current: 250/332
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G01J 5/0853 having infrared absorbers other than the usual absorber layers deposited on infrared detectors like bolometers, wherein the heat propagation between the absorber and the detecting element occurs within a solid
• CPC Class Codes: G01J 5/10 using electric radiation detectors
• CPC Class Codes: H01L 27/14649 Infrared imagers
• 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 two-dimensional infrared focal plane array of temperature detecting units is provided with the temperature detecting units being arranged for every pixel in a two-dimensional arrangement on a semiconductor substrate. Each temperature detecting unit is formed integrally with readout circuitry. Each temperature detecting unit further has a temperature detecting portion which is supported by support legs made of a high thermal resistance material to reduce heat flow to the semiconductor substrate. Each temperature detecting unit also has a temperature detecting element with an infrared ray absorbing portion which is spliced by at least one splicing pillar with the temperature detecting element.

Claims

1. A two-dimensional infrared focal plane array comprising temperature detecting units arranged for every pixel of a corresponding two-dimensional arrangement on a semiconductor substrate, each of said temperature detecting units being formed integrally with signal readout circuitry configured to provide an output signal indicating a change in incident infrared rays detected as a temperature change by an associated temperature detecting unit,

wherein each of said temperature detecting units includes a temperature detecting portion for every said pixel, each said temperature detecting portion being supported by support legs on said semiconductor substrate, each support leg comprising a high thermal resistance material reducing heat flow to said semiconductor substrate,

further wherein each said temperature detecting portion includes a temperature detecting element and a corresponding infrared ray absorbing portion, each infrared ray absorbing portion being spliced by at least one splicing pillar to each corresponding temperature detecting element and having an area substantially equal to an area of each pixel arranged in said two-dimensional arrangement except for a divisional margin space.

2. The two-dimensional infrared focal plane array of claim 1, wherein said temperature detecting portion is provided above a cavity portion which is formed in said semiconductor substrate.

3. The two-dimensional infrared focal plane array of claim 2, wherein an infrared absorbing structure comprising a reflection film and an interlayer insulating film is provided on at least one part of said infrared ray absorbing portion.

4. The two-dimensional infrared focal plane array of claim 3, wherein an optical resonant structure comprising a reflection film, an interlayer insulating film and a metal infrared ray absorbing film is provided on at least one part of said infrared ray absorbing portion.

5. The two-dimensional infrared focal plane array of claim 2, wherein at least one part of said splicing pillar is made of the same material as said infrared ray absorbing portion.

6. The two-dimensional infrared focal plane array of claim 2, wherein an optical resonant structure comprising a reflection film, an interlayer insulating film and metal infrared ray absorbing film is provided on at least one part of said infrared ray absorbing portion, and said splicing pillar is formed in one body with said reflection film.

7. The two-dimensional infrared focal plane array of claim 2, wherein at least one part of said splicing pillar is formed of a same material as said infrared ray absorbing portion and a gap is provided in a portion of the splicing pillar in contact with said temperature detecting portion.

8. The two-dimensional infrared focal plane array of claim 2, wherein at least one etching hole penetrating from said infrared ray absorbing portion to said cavity portion is provided in a vicinity of a center of said cavity portion.

9. The two-dimensional infrared focal plane array of claim 2, wherein an etching stop layer is provided of a material resistant to an etchant which is employed when forming said cavity portion in said semiconductor substrate around said cavity portion.

10. The two-dimensional infrared focal plane array of claim 2, wherein said temperature detecting element is formed on a surface of said infrared ray absorbing portion.

11. The two-dimensional infrared focal plane array of claim 1, wherein said temperature detecting portion is provided above a readout circuit on said semiconductor substrate.

12. The two-dimensional infrared focal plane array of claim 11, wherein an infrared absorbing structure comprising a reflection film and an interlayer insulating film is provided on at least one part of said infrared ray absorbing portion.

13. The two-dimensional infrared focal plane array of claim 11, wherein an optical resonant structure comprising a reflection film, an interlayer insulating film and a metal infrared ray absorbing film is provided on at least one part of said infrared ray absorbing portion.

14. The two-dimensional infrared focal plane array of claim 11, wherein at least one part of said splicing pillar is made of a same material as said infrared ray absorbing portion.

15. The two-dimensional infrared focal plane array of claim 11, wherein an optical resonant structure comprising a reflection film, an interlayer insulating film and metal infrared ray absorbing film is provided on at least one part of said infrared ray absorbing portion, and said splicing pillar is formed in one body with said reflection film.

16. The two-dimensional infrared focal plane array of claim 1, wherein a bolometer thin film is provided as said temperature detecting element.

17. The two-dimensional infrared focal plane array of claim 1, wherein a ferroelectric film having a pyroelectric effect is employed as said temperature detecting element.

18. The two-dimensional infrared focal plane array of claim 1, wherein said splicing pillar is provided below a position adjacent to a center of gravity of said infrared ray absorbing portion.

19. The two-dimensional infrared focal plane array of claim 1, wherein a thermal resistance of said splicing pillar is smaller than a thermal resistance of each support leg.