US4155779A
Expired / Lapsed
US
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Control techniques for annealing semiconductors
Assignee: AT&T Inc
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Filing: 1978-08-21
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Granted: 1979-05-22
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Expires: 1998-08-21
Abstract
Abstract Polycrystalline and amorphous semiconductors can be annealed using a laser or electron beam to restore or obtain crystal order by epitaxial regrowth on a crystal substrate. When the annealing occurs by liquid phase epitaxy, the presence and lifetime of a molten state at the region being annealed can be used to control the annealing process. Various control mechanisms are described.
Inventors
- 👤 David H. Auston
- 👤 Jene A. Golovchenko
- 👤 Richart E. Slusher
- 👤 Clifford M. Surko
- 👤 Thirumalai N. C. Venkatesan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:16
CPC Classifications
H; H10; H10P; H10P34/00; H10P34/40; H10P34/42; H10P14/00; H10P14/20; H10P14/38; H10P14/3802; H10P14/3808; Y; Y10; Y10S; Y10S148/00; Y10S148/09; Y10S148/093; Y10S438/00; Y10S438/965
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
117 words
A process for controllably converting nonsingle crystal material to single crystal material comprising the steps of: creating an amorphous or polycrystalline material on a single crystal substrate, exposing at least the amorphous or polycrystalline layer to a laser or electron beam for a time period sufficient to melt the entire thickness of the layer and a portion of the substrate, and removing the beam after said time period so that the molten material regrows epitaxially on the unmelted portion of the substrate, the invention characterized in that the reflectivity of the surface exposed to the beam is monitored during exposure, and the said time period is controlled in response to changes in the reflectivity of the surface.
Claim 2
Dependent Claim
117 words
A process for controllably converting nonsingle crystal material to single crystal material comprising the steps of: creating an amorphous or polycrystalline material on a single crystal substrate, exposing at least the amorphous or polycrystalline layer to a laser or electron beam for a time period sufficient to melt the entire thickness of the layer and a portion of the substrate, and removing the beam after said time period so that the molten material regrows epitaxially on the unmelted portion of the substrate, the invention characterized in that the reflectivity of the surface exposed to the beam is monitored during exposure, and the said time period is controlled in response to changes in the reflectivity of the surface.
Claim 3
Dependent Claim
30 words
The method of claim 1 in which the beam is pulsed at different energy levels and the pulses are controlled in response to changes in the reflectivity of the surface.
Claim 4
Dependent Claim
39 words
The method of claim 1 in which the beam is pulsed at a constant power level and the number of pulses to which the layer is exposed is controlled in response to changes in the reflectivity of the surface.
Claim 5
Dependent Claim
34 words
The method of claim 1 in which the layer is exposed to a single beam pulse and the duration of the pulse is controlled in response to changes in the reflectivity of the surface.
Claim 6
Dependent Claim
12 words
The method of claim 1 in which the layer is a semiconductor.
Claim 7
Dependent Claim
12 words
The method of claim 5 in which the substrate is a semiconductor.
Claim 8
Dependent Claim
11 words
The method of claim 6 in which the semiconductor is silicon.
Claim 9
Dependent Claim
12 words
The method of claim 6 in which the layer contains significant impurities.
Claim 10
Dependent Claim
25 words
The method of claim 8 in which the significant impurities have a conductivity type different from the conductivity type of the layer and the substrate.
Claim 11
Dependent Claim
19 words
The method of claim 5 in which the substrate is Al 2 O 3 and the layer is silicon.
Claim 12
Dependent Claim
13 words
The method of claim 1 in which the layer is essentially amorphous silicon.
Claim 13
Dependent Claim
20 words
The method of claim 1 in which the layer is amorphous and is created by implanting impurities into the substrate.
Claim 14
Dependent Claim
25 words
The method of claim 12 in which the impurities are of a conductivity type different from that of the substrate thus forming a p-n junction.
Claim 15
Dependent Claim
19 words
The method of claim 13 in which the p-n junction is relocated deeper within the substrate during the exposure.
Claim 16
Dependent Claim
28 words
The method of claim 14 in which the depth at which the p-n junction is relocated is controlled in response to changes in the reflectivity of the surface.
Claim 17
Dependent Claim
23 words
The method of claim 13 in which the beam exposure is controlled so that the p-n junction remains essentially in place during exposure.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-05-21 | 1982-11-20 | 1983-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-05-21 | 1986-11-20 | 1987-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-05-21 | 1990-11-20 | 1991-05-22 | $7700.00 | Window Closed / Lapsed |