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:
Aug. 11, 1992
Filed:
Dec. 12, 1991
Haruhito Shimakura, Toda, JP;
Manabu Kanou, Toda, JP;
Nippon Mining Co., Ltd., , JP;
Abstract
A method of producing a GaAs single crystal substrate comprises the steps of conducting a first-stage annealing by vacuum-sealing a GaAs single crystal wafer and arsenic in a heat-resistant vessel and heating the wafer to a temperature of 1050.degree. to 1150.degree. C. while exposing it to arsenic vapor pressure, cooling the wafer to room temperature at a cooling rate of 1.degree.-25.degree. C./min., removing the wafer from the vessel, etching the wafer and placing it in another vessel, conducting a second-stage annealing by heating the wafer to a temperature of 910.degree. to 1050.degree. C. in a non-oxidizing atmosphere, cooling the wafer to room temperature at a cooling rate of 1.degree.-25.degree. C./min., removing it from the vessel, etching the wafer, conducting a third-stage annealing by vacuum-sealing the wafer and arsenic in the heat-resistant vessel and heating the wafer to a temperature of 520.degree.-730.degree. C. while exposing it to arsenic vapor, and cooling the wafer at least down to 400.degree. C. at a cooling rate of 15.degree.-30.degree. C./min.