Electrical resistors – Resistance value responsive to a condition – Photoconductive
Patent
1985-06-07
1986-03-04
Albritton, C. L.
Electrical resistors
Resistance value responsive to a condition
Photoconductive
338 25, 250338, H01L 3108
Patent
active
045742634
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of preparation of an improved high performance thermal infrared detector and to the detector construction itself.
According to the invention a single detector or array of detectors, used in conjunction with a suitable optical system, detects the infrared heat radiation emitted from bodies, but will also operate over a broad wavelength region, from the near to far infrared.
The detector is of the resistance bolometer type, that is absorbed infrared radiation raises the temperature of the detector, thereby causing the electrical resistance to change. This change is observed by virtue of the variation in an electrical bias current or voltage applied to the detector.
It must be understood that detectors of this type have been previously described and reference may be had to the following papers:
(1) A paper by C. B. AIKEN, W. H. CARTER Jr, and F. S. PHILLIPS entitled "The Production of Film Type Bolometers with Rapid Response", published in Rev.Sci.Ins., Vol. 17, No. 10, p. 377, 1946.
(2) A paper by B. H. BILLINGS, W. L. HYDE and E. F. BARR entitled "Construction and Characteristics of Evaporated Nickel Bolometers", Rev.Sci.Ins., Vol. 18, No. 6, p. 429. June 1947.
(3) A paper by K. YOSIHARA entitled "An Investigation of the Properties of Bolometers made by Vacuum Evaporation", Science of Light, Vol. 5, No. 2, p. 29. 1956.
(4) A paper by W. R. BLEVIN and W. J. BROWN entitled "Large-area Bolometers of Evaporated Gold", J.Sci.Ins., Vol. 42, No. 1, p. 19, January 1965.
However, the material properties of these detectors are not optimum, and it is an object of the present invention to improve the detecting ability of devices of this type. The invention deals with the method of preparation and the introduction of new materials technology.
(5) A recent report by GOSCH under the title "Thin Film enhances Bolometer's Sensitivity", published in Electronics, 28 Feb. 1980, page. 75, describes a gold film bolometer which is said to have exceptionally high performance, but the information given is incomplete.
Patents on bolometers are also well known, for example, the patent to R. J. HAVENS et al, U.S. Pat. No. 2,516,873; the patent to J. LEBLANC et al, U.S. Pat. No. 4,116,063; the patent to P. PAUL, U.S. Pat. No. 3,745,360; the patent to B. NORTON et al U.S. Pat. No. 3,202,820; and the patent to E. H. EBERHARDT AVS No. 220,305. However these patents do not describe either the method of preparation or the materials technology which are features of the present invention.
It is further understood that the general concept of a bolometer detector comprised of a thin infrared sensitive film deposited onto a pellicle which is supported over an aperture is described in the patent by R. J. HAVEN et al and in the papers cited above, and consequently is not specifically claimed in the present invention.
The detector according to this invention is comprised essentially of an ultra thin metal film, vaccum deposited on to a thin dielectric or semiconductor pellicle. The pellicle is supported at its edges by a suitable substrate material, on which are formed metal bonding pads. Electrical connection is made between the radiation sensitive detector element and the bonding pads by means of thin metal contacts.
A hole, or alternatively a channel or slot pattern is drilled through or etched into the substrate, and the pellicle is freely-supported over the recess thus formed. A single detector element in a multi-element detector array has the pellicle supported over an etched channel, and a metal film interconnect joins the detector contacts to the bonding pads.
The detector or detector array is mounted inside a microcircuit package fitted with an infrared transmitting window. Depending on the desired performance, the package is either evacuated or filled to a predetermined pressure with a selected gas.
In order however to fully understand the nature of the invention, embodiments thereof will now be described with reference to the accompanying drawings to which however the invention is not necessarily limite
REFERENCES:
patent: 2423476 (1947-07-01), Billings et al.
patent: 2516873 (1950-08-01), Havens et al.
patent: 3069644 (1962-12-01), Eberhardt
patent: 3229235 (1966-01-01), Bernath
patent: 3693011 (1972-09-01), De Vaux et al.
patent: 3715288 (1973-02-01), Risgin
patent: 4061917 (1977-12-01), Gorauson et al.
patent: 4224520 (1980-09-01), Greene et al.
patent: 4302674 (1981-11-01), Adachi et al.
patent: 4349808 (1982-09-01), Kraus
Gosch, J. "Thin-Film Enhances Balometer's Sensitivity", Electronics Feb. 28, 1980 pp. 74-76.
Elliot, D. J., Integrated Circuit Fabrication Technology, McGraw Book Co. .COPYRGT.1982 pp. 18-21, 24-25, 32-33, and 259.
Coombe, R. A., The Electrical Properties and Applications of Thin Films, Sir Issac Pitman & Sons Ltd. .COPYRGT.1967 pp. 88, 133.
Bruck et al. in Electronics, vol. 51, No. 16, pp. 99 to 104, 1978.
Albritton C. L.
Lateef M. M.
The Commonwealth of Australia
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