US3839991A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for the production of homogeneous and plane parallel epitactic growth layers of semiconducting compounds by melt epitaxy
Assignee: Siemens AG
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Filing: 1972-02-04
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Granted: 1974-10-08
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Expires: 1992-02-04
Abstract
Abstract Process and apparatus for preparing doped plane parallel epitactic growth layers of semiconducting compounds, especially GaAs, by melt epitaxy, using a non-stoichiometric metal melt. A thick walled cylindrical melting crucible is used to receive the semiconducting compound. A cooling finger capable of being unscrewed is near the bottom of the melt area. A substrate is placed between the hollow crucible and the cooling finger, by a thermal resistance which increases toward the center in that portion of the cooling finger on which the substrate bears, so that the temperature gradient, before and during epitactic coating, is in the axial direction only and not in the radial direction thereby resulting in very planar growth layers.
Inventors
- 👤 G Winstel
- 👤 P Jochen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:35
CPC Classifications
C; C30; C30B; C30B19/00; C30B19/06; C30B19/061; C30B19/08
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
164 words
Apparatus for preparing doped plane parallel epitactic growth layers of semiconductive compounds which comprises a cylindrical melt crucible for receiving the molten mass, said crucible being located in a quartz furnace and being rotatable therewith about a mutual transverse axis, said melt crucible being in two parts, the first part of which being a thick walled hollow body and the other part a threaded cooling finger, means defining a space for receiving therein a substrate disc between said hollow body and said cooling finger, and a bearing surface for a substrate disc at the threaded part of the cooling finger, said cooling finger having a thermal resistance which increases toward the center, an induction coil outside the furnace for heating the melting crucible, and means communicating with the interior of said furnace for introducing into said furnace a protective gas atmosphere, the tubular body and the threaded cooling finger of the melt crucible being of graphite and being coated with a hard carbon layer.
Claim 2
Dependent Claim
164 words
Apparatus for preparing doped plane parallel epitactic growth layers of semiconductive compounds which comprises a cylindrical melt crucible for receiving the molten mass, said crucible being located in a quartz furnace and being rotatable therewith about a mutual transverse axis, said melt crucible being in two parts, the first part of which being a thick walled hollow body and the other part a threaded cooling finger, means defining a space for receiving therein a substrate disc between said hollow body and said cooling finger, and a bearing surface for a substrate disc at the threaded part of the cooling finger, said cooling finger having a thermal resistance which increases toward the center, an induction coil outside the furnace for heating the melting crucible, and means communicating with the interior of said furnace for introducing into said furnace a protective gas atmosphere, the tubular body and the threaded cooling finger of the melt crucible being of graphite and being coated with a hard carbon layer.
Claim 3
Dependent Claim
18 words
The apparatus of claim 1, wherein said bearing surface for the substrate contains at least one central bore.
Claim 4
Dependent Claim
25 words
The apparatus of claim 2, wherein said bearing surface for the said substrate has a larger central bore and a concentric ring of smaller bores.
Claim 5
Dependent Claim
23 words
Apparatus of claim 3, including a heat insulating disc of a high melting oxide disposed between the substrate disc and the bearing surface.
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) | 1977-10-07 | 1978-04-08 | 1978-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-07 | 1982-04-08 | 1982-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-07 | 1986-04-08 | 1986-10-08 | $7700.00 | Window Closed / Lapsed |