US3670404A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating a semiconductor
Assignee: NEC Corp
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Filing: 1969-06-06
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Granted: 1972-06-20
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Expires: 1989-06-06
Abstract
Abstract Individual small semiconductor elements are fabricated and the front and back surfaces of the elements aligned by utilizing the difference in penetration of infrared rays as viewed from the other side of the elements by an infrared optic system. The difference is afforded by providing the reverse side of the semiconductor element with an irregularity in the thickness of either an insulating film, a photoresist film, the density of a doped impurity, or irregularities in the underside surface of the semiconductor element itself.
Inventors
- 👤 Mototaka Kamoshida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 08:02
CPC Classifications
H; H10; H10W; H10W40/00; H10W40/10; H10D; H10D99/00; H10P; H10P95/00; H10W72/00; H10W72/60; H10W72/071; H10W72/072; H10W72/07231; H10W72/07236; H10W72/851; H10W72/874; H10W72/877; Y; Y10; Y10S; Y10S438/00; Y10S438/942
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
167 words
A method of fabricating a semiconductor comprising the steps of providing a semiconductor wafer having insulated passivation films on both sides thereof, selectively etching a pattern at the portions of said wafer to be separated into a plurality of pellets on the back side of said wafer by means of a photographiC etching process positioning a mask at the front side of said wafer, projecting infrared rays onto a photoresist film on the back side of said wafer and said pattern and observing the difference of the penetrating infrared rays between the selectively removed portions of the wafer and the other portions of said wafer so that alignment of said mask and said pattern selectively formed on the back side of the said wafer is achieved; adhering a predetermined metal over the back side of the wafer; making a crack at the portions on said wafer corresponding to the outer periphery of each of the pellets to be separated, and separating the integral wafer into individual pellets.
Claim 2
Dependent Claim
14 words
A method as set forth in claim 2, wherein said semiconductor is of silicon.
Claim 3
Dependent Claim
31 words
A method as set forth in claim 2, wherein said selectively etching steps for the portion to be separated is performed in such a degree that its thickness provides easy separation.
Claim 4
Dependent Claim
38 words
The method of claim 1, further comprising the steps of adhering a metal coating on said one side of said semiconductor wafer, and thereafter separating said wafer into a plurality of individual pellets along said reduced thickness portions.
Claim 5
Independent Claim
113 words
A method of fabricating a semiconductor device comprising the steps of: providing a semiconductor wafer having cleaned major surfaces, selectively etching a pattern of reduced thickness portions on one of said major surfaces by means of a photographic etching process, said reduced thickness portions enabling the wafer to be separated into a plurality of pellets projecting infrared rays onto said one of said major surfaces and said pattern, and positioning a mask on the other of said major surfaces in registration with said pattern by way of observing the difference of the penetrating infrared rays between said portions and those portions of said wafer which have not been subjected to the selective etching.
References Cited (Backward Citations)
US3447235A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |