The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 05, 1998
Filed:
Dec. 27, 1995
Donovan L Barrett, New Smyrna Beach, FL (US);
Richard N Thomas, Murrysville, PA (US);
Raymond G Seidensticker, deceased, late of Forest Hills, PA (US);
Richard H Hopkins, Murrysville, PA (US);
Northrop Grumman Corporation, Los Angeles, CA (US);
Abstract
A method for producing crystals of silicon carbide in a furnace. The furnace has a crucible with a cavity in which the cavity has first and second spaced-apart regions. The crucible cavity of the furnace is capable of being heated, preferably by induction or resistance heating, with insulation placed around the crucible and crucible cavity. A source material of silicon carbide is provided at the first region of the crucible cavity, and a monocrystalline seed is placed at the second region of the crucible cavity. A first growth stage is then conducted in which the first region and the second region of the crucible cavity are heated to at least the sublimation temperature of silicon carbide under substantially isothermal conditions. Then, a second growth stage is conducted in which a temperature gradient is provided between the first and the second region of the crucible cavity, such that the seed in the second crucible region is kept at a temperature lower than a temperature of the first crucible region.