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US 2013/0256786 A1Published application
Trench mosfet with shielded electrode and avalanche enhancement region
AssigneeFeei Cherng Enterprise Co., Ltd.
InventorFu-Yuan HSIEH
Life of this patent
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Abstract
A trench MOSFET with shielded electrode and improved avalanche enhancement region is disclosed. The inventive structure can achieve a better avalanche capability by applying an improved avalanche enhancement region having a same doping concentration as the epitaxial layer where said trench MOSFET is formed without increasing Rds.
Claims19
A trench MOSFET, comprising:
- a substrate of a first conductivity type;
- an epitaxial layer of said first conductivity type onto said substrate, said epitaxial layer having a lower doping concentration than said substrate;
- a plurality of active trenches formed in said epitaxial layer in an active area, each comprising a shielded electrode in a lower portion and a gate electrode in an upper portion, wherein said shielded electrode is insulated from said epitaxial layer by a field oxide and said gate electrode is insulated from source regions of said first conductivity type and body regions of a second conductivity type by a gate oxide, wherein said shielded electrode and said gate electrode are insulated from each other by an inter-poly insulating layer;
- and
- avalanche enhancement regions of said first conductivity type formed adjacent sidewalls of each of said active trenches below said body regions and towards a bottom of each of said active trenches, wherein said avalanche enhancement regions having a lower doping concentration than said epitaxial layer.
2 more elements
A method of making a trench MOSFET with shielded electrode, comprising:
- forming a plurality of active trenches in an epitaxial layer of a first conductivity type supported onto a substrate of said first conductivity type;
- forming a shielded electrode padded by a field oxide in a lower portion of each of said active trenches;
- carrying out angle ion implantations to form avalanche enhancement regions of said first conductivity type in said epitaxial layer along upper sidewalls of each of said active trenches before forming a gate electrode in an upper portion of each of said active trenches, wherein said avalanche enhancement regions having a lower doping concentration than said epitaxial layer.
Dependencies are inferred from the claim text.