US3655540A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making semiconductor device components
Assignee: AT&T Inc
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Filing: 1970-06-22
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Granted: 1972-04-11
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Expires: 1990-06-22
Abstract
Abstract Extremely thin semiconductor wafers are formed by growing an Nconductivity epitaxial layer on an N -type substrate. A Schottky barrier contact is formed on the epitaxial layer and the assembly is immersed in an appropriate fluid for electrolytic etching. Because of differential etch rates as a function of conductivity, and with an appropriate contact voltage, the substrate is selectively dissolved, leaving only the thin epitaxial layer adhered to the contact. The contact is then removed, leaving the epitaxial layer as an independent ultrathin wafer.
Inventors
- 👤 John Calhoun Irvin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:52
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/613; Y; Y10; Y10S; Y10S148/00; Y10S148/051; Y10S148/117; Y10S148/135; Y10S438/00; Y10S438/977
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
37 words
The method of claim 1 wherein: the wafer is silicon and the step of forming a thin layer comprises the step of epitaxially growing a thin layer of silicon having a significantly higher resistivity than the substrate.
Claim 2
Dependent Claim
46 words
The method of claim 2 wherein: the step of forming a Schottky barrier contact on the layer comprises the step of evaporating metal onto the layer; and further comprising the step of removing the contact comprising the step of selectively etching the metal from the layer.
Claim 3
Dependent Claim
36 words
The method of claim 2 wherein: the step of forming a Schottky barrier contact comprises the step of coating the layer with a conductive adhesive; and forcing a flat metal contact against the adhesive under pressure.
Claim 4
Dependent Claim
30 words
The method of claim 2 wherein: the electrolyte is hydrofluoric acid; and the step of sealing the periphery comprises the step of covering the periphery of the substrate with wax.
Claim 5
Dependent Claim
33 words
The method of claim 2 wherein the semiconductor layer and the semiconductor substrate are of N-type conductivity; and the step of applying a voltage comprises the step of forward-biasing the Schottky barrier contact.
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) | 1975-04-11 | 1975-10-11 | 1976-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-11 | 1979-10-11 | 1980-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-11 | 1983-10-11 | 1984-04-11 | $7700.00 | Window Closed / Lapsed |