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:
Mar. 26, 1996
Filed:
May. 19, 1995
Yoko Inoue, Yokohama, JP;
Shuichi Samata, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
The semiconductor substrate is manufactured by growing a semiconductor crystal in accordance with CZ method; forming a substrate from the semiconductor crystal; and heat treating the formed substrate at 1150.degree. C. or higher for 30 min or longer in non-oxidizing atmosphere (e.g., 1200.degree. C. for 1 hour in hydrogen gas). In the formed wafer, the density of bulk micro-defects is 5.times.10.sup.2 to 5.times.10.sup.6 pieces per cm.sup.-3 in the surface area, but 5.times.10.sup.7 pieces per cm.sup.-3 or more in an 20 .mu.m or deeper from the surface. To confirm the depth profile of BMD density, the substrate is further heat treated at 780.degree. C. for 3 hours in oxygen atmosphere and successively at 1000.degree. C. for 16 hours in oxygen atmosphere.