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US3863333A
Expired / Lapsed
US
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Methods for making semiconductor devices
Assignee: AT&T Inc
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Filing: 1973-08-31
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Granted: 1975-02-04
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Expires: 1993-08-31
Abstract
Abstract Ultrasonic agitation in a liquid is used in two ways in the fabrication of small semiconductor diodes. First, a siliconcontaining 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
2026-10-27 17:16
CPC Classifications
H; H10; H10P; H10P95/00; B; B01; B01J; B01J19/00; B01J19/08; B01J19/10; H10D; H10D99/00
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
148 words
A PROCESS FOR MAKING SEMICONDUCTOR DEVICES COMPRISING THE STEPS OF: FORMING A FIRST THIN LAYER OF GOLD ON ONE SIDE OF A SILICON WAFER; FORMING A PLATINUM-SILICIDE LAYER ON THE OTHER SIDE OF THE WAFER; FORMING A SECOND LAYER OF GOLD OVER THE PLATINUM-SILICIDE LAYER; DEFINING A PLURALITY OF DEVICES BY ETCHING PORIONS OF THE SECOND GOLD LAYER, THEREBY TO EXPOSE PART OF THE PLATNIUMSILICIDE LAYER; SUBJECTING THE EXPOSED PLATINUM-SILICIDE LAYER TO A SILICON ETCHANT, THEREBY TO WEAKEN ITS STRUCTURE; IMMERSING THE WAFER IN A LIQUID AND SUBJECTING IT TO ULTRASONIC AGITATION OF SUFFICIENT INTENSITY TO REMOVE THE EXPOSED AND WEAKENED PLATINUM-SILICIDE, THEREBY TO EXPOSE PART OF THE SILICON WAFER; SUBJECTING THE EXPOSED SILICON TO A SILICON ETCH FOR A SUFFICIENT TIME TO ETCH THROUGH THE WAFER TO THE FIRST THIN LAYER OF GOLD, WHEREBY A PLURALITY OF DEFINED DEVICES ARE HELD TOGETHER BY THE FIRST LAYER; AND
Claim 2
Dependent Claim
148 words
A PROCESS FOR MAKING SEMICONDUCTOR DEVICES COMPRISING THE STEPS OF: FORMING A FIRST THIN LAYER OF GOLD ON ONE SIDE OF A SILICON WAFER; FORMING A PLATINUM-SILICIDE LAYER ON THE OTHER SIDE OF THE WAFER; FORMING A SECOND LAYER OF GOLD OVER THE PLATINUM-SILICIDE LAYER; DEFINING A PLURALITY OF DEVICES BY ETCHING PORIONS OF THE SECOND GOLD LAYER, THEREBY TO EXPOSE PART OF THE PLATNIUMSILICIDE LAYER; SUBJECTING THE EXPOSED PLATINUM-SILICIDE LAYER TO A SILICON ETCHANT, THEREBY TO WEAKEN ITS STRUCTURE; IMMERSING THE WAFER IN A LIQUID AND SUBJECTING IT TO ULTRASONIC AGITATION OF SUFFICIENT INTENSITY TO REMOVE THE EXPOSED AND WEAKENED PLATINUM-SILICIDE, THEREBY TO EXPOSE PART OF THE SILICON WAFER; SUBJECTING THE EXPOSED SILICON TO A SILICON ETCH FOR A SUFFICIENT TIME TO ETCH THROUGH THE WAFER TO THE FIRST THIN LAYER OF GOLD, WHEREBY A PLURALITY OF DEFINED DEVICES ARE HELD TOGETHER BY THE FIRST LAYER; AND
Claim 3
Dependent Claim
24 words
The process of claim 1 wherein: the first thin layer of gold has a thickness of the order of between 2,000 and 10,000 angstroms.
Claim 4
Dependent Claim
21 words
The process of claim 2 wherein: the platinum-silicide layer has a thickness on the order of from 500 to 2,000 angstroms.
Claim 5
Dependent Claim
17 words
The process of claim 3 wherein: the thickness of the semiconductor is less than about 40 micrometers.
Claim 6
Dependent Claim
27 words
The process of claim 4 wherein: the step of defining the devices comprises the step of: defining devices that have diameters of less than about 10 mils.
Claim 7
Dependent Claim
96 words
A process for making semiconductor devices comprising the steps of: forming a first silicon-containing conductive metal layer on one surface of a silicon wafer; forming a second metal layer over the first metal layer; etching parts of the second metal layer, thereby to expose parts of the first metal layer; exposing the first metal layer to a silicon etch thereby to weaken its structure; immersing the wafer in a liquid and subjecting it to ultrasonic agitation of a sufficient intensity to remove the exposed weakened first metal layer, thereby exposing part of the first silicon wafer.
Claim 8
Dependent Claim
96 words
A process for making semiconductor devices comprising the steps of: forming a first silicon-containing conductive metal layer on one surface of a silicon wafer; forming a second metal layer over the first metal layer; etching parts of the second metal layer, thereby to expose parts of the first metal layer; exposing the first metal layer to a silicon etch thereby to weaken its structure; immersing the wafer in a liquid and subjecting it to ultrasonic agitation of a sufficient intensity to remove the exposed weakened first metal layer, thereby exposing part of the first silicon wafer.
Claim 9
Dependent Claim
11 words
The process of claim 6 wherein: the first metal is platinum-silicide.
Claim 10
Dependent Claim
13 words
The process of claim 6 wherein: the first metal is gold-silicon eutectic alloy.
Claim 11
Dependent Claim
19 words
The process of claim 6 wherein: the thickness of the first metal layer is approximately 500 to 5,000 angstroms.
Claim 12
Dependent Claim
10 words
The process of claim 6 wherein: the etchant is HNO3:HF.
Claim 13
Dependent Claim
28 words
The process of claim 9 wherein: the exposing step comprises the step of immersing the first metal layer in a 20:1 solution of HNO3:HF for about 1 minute.
Claim 14
Dependent Claim
39 words
The process of claim 6 wherein: the first layer has a thickness of approximately 600 angstroms; and the exposing step comprises the step of immersing the first metal layer in a 20:1 solution of HNO3:HF for approximately 50 seconds.
Claim 15
Dependent Claim
40 words
The process of claim 6 wherein: the first layer has a thickness of approximately 2,000 angstroms; and the exposing step comprises the step of immersing the first layer in a 20:1 solution of HNO3:HF for approximately 70 - 75 seconds.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |