US3955270A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods for making semiconductor devices
Assignee: AT&T Inc
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Filing: 1974-11-15
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Granted: 1976-05-11
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Expires: 1994-11-15
Abstract
Abstract Ultrasonic agitation in a liquid is used in two ways in the fabrication of small semiconductor diodes. First, a silicon-containing metal layer such as platinum-silicide is removed by exposing it to a silicon etchant and then ultrasonically agitating it. Second, an array of diodes connected by a gold film back contact is separated into individual devices by ultrasonically agitating the array to break up the gold film.
Inventors
- 👤 Andrew Loya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 09:00
CPC Classifications
B; B01; B01J; B01J19/00; B01J19/08; B01J19/10; H; H10; H10P; H10P50/00; H10P50/69; H10P50/691; H10P54/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
98 words
A process for making semiconductor devices comprising the steps of: forming a first thin metal layer on one side of a semiconductor wafer; forming a second metal layer on the opposite side of the semiconductor wafer; defining a plurality of devices by, first, etching part of the second metal layer, second, etching a corresponding part of the semiconductor wafer, third, immersing the wafer in a liquid, and fourth, subjecting the wafer to non-localized ultrasonic agitation of said liguid, said agitation being of sufficient intensity to rupture the first thin metal layer, thereby to break apart the defined devices.
Claim 2
Dependent Claim
98 words
A process for making semiconductor devices comprising the steps of: forming a first thin metal layer on one side of a semiconductor wafer; forming a second metal layer on the opposite side of the semiconductor wafer; defining a plurality of devices by, first, etching part of the second metal layer, second, etching a corresponding part of the semiconductor wafer, third, immersing the wafer in a liquid, and fourth, subjecting the wafer to non-localized ultrasonic agitation of said liguid, said agitation being of sufficient intensity to rupture the first thin metal layer, thereby to break apart the defined devices.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein: the first metal layer has a thickness of approximately 2,000 to 10,000 angstroms.
Claim 4
Dependent Claim
19 words
The process of claim 2 wherein: the major part of the first metal layer comprises a layer of gold.
Claim 5
Dependent Claim
10 words
The process of claim 3 wherein: the semiconductor is silicon.
Claim 6
Dependent Claim
138 words
A process for making microwave devices comprising the steps of: forming a first, thin, metal contact comprised principally of gold and having a thickness less than about one micrometer on one side of a silicon wafer; forming a second metal contact comprised principally of gold and having a thickness greater than the first contact but less than about four micrometers on the opposite side of the silicon wafer; defining an array of devices each having a diameter between about one and ten mils by first, etching the second metal contact, second, etching a corresponding part of the silicon wafer, third, immersing the wafer in a liquid, and fourth, subjecting the wafer to non-localized ultrasonic agitation of said liguid, said agitation being of sufficient intensity to rupture the first thin metal contact thereby to break apart the defined devices.
Claim 7
Dependent Claim
138 words
A process for making microwave devices comprising the steps of: forming a first, thin, metal contact comprised principally of gold and having a thickness less than about one micrometer on one side of a silicon wafer; forming a second metal contact comprised principally of gold and having a thickness greater than the first contact but less than about four micrometers on the opposite side of the silicon wafer; defining an array of devices each having a diameter between about one and ten mils by first, etching the second metal contact, second, etching a corresponding part of the silicon wafer, third, immersing the wafer in a liquid, and fourth, subjecting the wafer to non-localized ultrasonic agitation of said liguid, said agitation being of sufficient intensity to rupture the first thin metal contact thereby to break apart the defined devices.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-05-11 | 1979-11-10 | 1980-05-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-11 | 1983-11-10 | 1984-05-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-11 | 1987-11-10 | 1988-05-11 | $7700.00 | Window Closed / Lapsed |