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:
Jun. 08, 1993
Filed:
Aug. 13, 1991
Minoru Taguchi, Oomiya, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
Buried layers of a second conductivity type are formed in a plurality of portions of a surface region of a semiconductor substrate of a first conductivity type, and an epitaxial layer of the first conductivity type is formed on the buried layers and the semiconductor substrate. A plurality of well regions of the second conductivity type are formed in the epitaxial layer in contact with the buried layers, and a region of the second conductivity type with a high impurity concentration is formed in one of the well regions in contact with the buried layers. A field insulating layer is formed on a surface region of the semiconductor substrate between the well regions. An impurity is ion-implanted in a portion substantially immediately below the field insulating film a plurality of times to form inversion preventing layers of the first conductivity type having a plurality of impurity concentration peaks. Active elements are formed in the epitaxial layer of the first conductivity type and the well regions.