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:
Dec. 08, 1992
Filed:
Mar. 30, 1990
Katsuto Katoh, Tokyo, JP;
Kiyomi Naruke, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
An improvement for a semiconductor device in which memory elements and logic elements are formed on the same substrate is disclosed. The semiconductor device is formed so that a concentration of the field inversion preventive layer below the field oxide film within the region where memory elements are formed is higher than a concentration of the field inversion preventive layer below the field oxide film within the region where logic elements are formed. For the method of manufacturing a semiconductor substrate according to this invention which realizes such a structure, there is a method of allowing the concentrations of field inversion preventive layers within the memory element region and within the logic element region to be differently changed, respectively, and a method of first forming field inversion preventive layers within the both regions so that they have a low concentration, and implementing ion-implantation only to the memory element region for a second time under the state where the logic element region is covered with resist, to thus provide an inversion preventive layer of high concentration.