High density trench DMOS transistor with trench bottom implant

US5929481A · kind A · utility

Assignee

• SILICONIX INCORPORATED · US

Inventors

• Fwu-Iuan Hshieh · Saratoga, US
• Brian H. Floyd · Sunnyvale, US
• Mike F. Chang · Cupertino, US
• Danny Chi Nim · San Jose, US
• Daniel Ng · Campbell, US

Key dates

• Filing date: Nov 4, 1997
• Grant date: Jul 27, 1999
• Expiry date: Nov 4, 2017

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D62/393

Abstract

A trenched DMOS transistor overcomes the problem of a parasitic JFET at the trench bottom (caused by deep body regions extending deeper than the trench) by providing a doped trench bottom implant region at the bottom of the trench and extending into the surrounding drift region. This trench bottom implant region has the same doping type, but is more highly doped, than the surrounding drift region. The trench bottom implant region significantly reduces the parasitic JFET resistance by optimizing the trench bottom implant dose, without creating reliability problems.