US3925879A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of fabricating photosensitive Darlington device
Assignee: Sensor Technology Inc
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Filing: 1974-09-11
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Granted: 1975-12-16
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Expires: 1994-09-11
Abstract
Abstract Photo-Darlington devices having a response within a narrow range of current output for a certain illumination level are produced by initially providing each device with a light-admitting opening of smaller than requisite size. The device outputs are measured separately, and based on such measurements, the individual openings are enlarged sufficiently so that the output current from each device falls within the requisite range. For improved performance, each photo-Darlington device has a pair of emitters spaced on opposite sides of the light admitting opening. This provides better efficiency and results in more consistent output despite non-uniform illumination of the device.
Inventors
- 👤 Harold Weinstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:31
CPC Classifications
H; H10; H10F; H10F71/00; H10F30/00; H10F30/20; H10F30/21; H10F30/24; H10F39/00; H10F39/10; H10F39/103; H10F99/00; H10P; H10P95/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
182 words
A process for fabricating a Darlington photodetector device having light response characteristics within a specified narrow range, comprising; forming in a semiconductor substrate a relatively large base region for a phototransistor and a base region for a second transistor, and forming emitter regions in the respective base regions, producing an insulating layer over both said transistors, said layer having openings to both the emitter of said phototransistor and to the base of the second transistor, depositing an optically opaque metalization layer over a substantial portion of the base of said phototransistor and over the openings to said emitter and the second transistor base so as to electrically interconnect the same, providing an initial light-admitting opening of controlled area through said opaque metalization for passage of light to said phototransistor base region, the area of said initial opening being of such a size that the desired output current is not obtained, measuring the device output current while said device is illuminated with light of known level, and modifying the size of said opening to achieve an output current within the specified narrow range.
Claim 2
Dependent Claim
182 words
A process for fabricating a Darlington photodetector device having light response characteristics within a specified narrow range, comprising; forming in a semiconductor substrate a relatively large base region for a phototransistor and a base region for a second transistor, and forming emitter regions in the respective base regions, producing an insulating layer over both said transistors, said layer having openings to both the emitter of said phototransistor and to the base of the second transistor, depositing an optically opaque metalization layer over a substantial portion of the base of said phototransistor and over the openings to said emitter and the second transistor base so as to electrically interconnect the same, providing an initial light-admitting opening of controlled area through said opaque metalization for passage of light to said phototransistor base region, the area of said initial opening being of such a size that the desired output current is not obtained, measuring the device output current while said device is illuminated with light of known level, and modifying the size of said opening to achieve an output current within the specified narrow range.
Claim 3
Dependent Claim
97 words
A process acccording to claim 1 wherein said providing step comprises, placing a first mask over said metalization layer, said first mask having an aperature of a first, too small size, and etching away said metal of said layer beneath the aperture of said mask to form an initial opening, and wherein said modifying step comprises, placing a second mask over said metalization layer, said second mask having an aperture of a second larger size situated concentrically with said initial opening, and etching away the metal of said layer to enlarge the size of said light-admitting opening.
Claim 4
Dependent Claim
36 words
a process according to claim 2 wherein the area ratio between said first and second size apertures is proportional to the ratio between the output current measured during said measuring step and the desired output current.
Claim 5
Dependent Claim
36 words
A process according to claim 1 wherein said initial opening is of too small size, and wherein said modifying comprises removing additional metal from said layer by laser to enlarge the size of said light-admitting opening.
Claim 6
Dependent Claim
26 words
A process according to claim 4 wherein said measuring and modifying steps are carried out concurrently, said laser being controlled automatically in response to said measuring.
Claim 7
Dependent Claim
50 words
A process according to claim 1 wherein said forming step includes forming a pair of spaced emitter regions in said phototransistor base region, said emitter regions being situated on opposite sides of said light-admitting opening to provide better efficiency and more consistent output even with non-uniform illumination of said phototransistor.
References Cited (Backward Citations)
US3013232A
Cited
US3761326A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-15 | 1979-06-16 | 1979-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-15 | 1983-06-16 | 1983-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-15 | 1987-06-16 | 1987-12-16 | $7700.00 | Window Closed / Lapsed |