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. 12, 2007
Filed:
May. 13, 2004
Naresh Thapar, Los Angeles, CA (US);
Naresh Thapar, Los Angeles, CA (US);
International Rectifier Corporation, El Segundo, CA (US);
Abstract
A trench type power MOSFET has a thin vertical gate oxide along its side walls and a thickened oxide with a rounded bottom at the bottom of the trench to provide a low Rand increased Vand Vand a reduced Miller capacitance. The walls of the trench are first lined with nitride to permit the growth of the thick bottom oxide to, for example 1000 Å to 1400 Å and the nitride is subsequently removed and a thin oxide, for example 320 Å is regrown on the side walls. In another embodiment, the trench bottom in amorphized and the trench walls are left as single crystal silicon so that oxide can be grown much faster and thicker on the trench bottom than on the trench walls during an oxide growth step. A reduced channel length of about 0.7 microns is used. The source diffusion is made deeper than the implant damage depth so that the full 0.7 micron channel is along undamaged silicon. A very lightly doped diffusion of 1000 Å to 2000 Å in depth could also be formed around the bottom of the trench and is depleted at all times by the inherent junction voltage to further reduce Miller capacitance and switching loss.