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. 30, 1995
Filed:
Apr. 12, 1994
Akira Sudo, Yokohama, JP;
Kabushiki Kaisha Toshiba, , JP;
Abstract
An element separating oxide film is formed on a P-type semiconductor substrate by means of a selective oxidation method, and then a gate oxide film is formed on the element separating oxide film by a thermal oxidation method. A gate electrode film made of an N-type polysilicon material is formed so as to extend along a step portion of the element separating oxide film on the semiconductor substrate. The upper surface of the gate electrode film is flattened by means of a surface polishing method. Then, isotropic etching is performed by using a resist pattern as a mask, thereby forming a gate electrode. Since in the method the upper surface of the gate electrode film in the flattened, the semiconductor substrate is prevented from being subject to over-etching when a gage electrode is formed, so that the changes of characteristics of MOS transistors are prevented whose gate insulative films have been becoming thinner as their elements have been finer.