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. 23, 1998
Filed:
Jan. 22, 1997
Noboru Matsuda, Kawasaki, JP;
Yoshiro Baba, Yokohama, JP;
Satoshi Yanagiya, Kawasaki, JP;
Masanobu Tsuchitani, Tokyo, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
In a vertical field effect transistor having a trench gate and a method of manufacturing the same according to the present invention, p-type base and n.sup.+ -type source diffusion layers are formed in this order in a surface region of an n.sup.31 -type epitaxial layer on an n.sup.+ -type semiconductor substrate. A trench is then provided to such a depth as to penetrate the diffusion layers. A dope polysilicon layer is deposited and buried into the trench with a gate insulation film interposed between them. The polysilicon layer is etched to have the same level as that of the entrance of the trench, and a dope polysilicon layer 18 is selectively grown thereon, thereby forming a trench gate in which an upper corner portion of the trench is not covered with a gate electrode. Consequently, the concentration of electric fields at the corner portion can be mitigated thereby to increase an absolute withstand voltage of the gate and the variations in threshold voltage can be suppressed in a BT test.