Angled Gate Trenches With Partial Shielding for Power MOSFETs

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Solution Overview

Problem

Conventional gate trench power MOSFETs face challenges in implementing deep shielding regions and connection patterns that effectively reduce electric field levels in the gate oxide layer during reverse blocking operations without sacrificing significant transistor channel area.

Innovation Solution

The proposed solution involves forming deep shielding connection patterns that electrically connect deep shielding regions to the source contact, with these patterns extending only a portion of the gate trench sidewalls, thereby minimizing channel area sacrifice and enhancing device performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If deep shielding connection patterns extend along the gate trench sidewalls to reduce electric field levels, then reliability is improved, but transistor channel area is reduced

Engineering Contradiction:

Improvegate oxide layer protectionVSAvoidtransistor channel area

Core Design Contradiction:

ReliabilityVSArea of moving object

Solution Approach 1:

The deep shielding connection patterns extend only along a portion (e.g., 10-90%) of the gate trench sidewalls rather than the full length, providing sufficient electric field shielding to protect the gate oxide layer while preserving the majority of the transistor channel area for current conduction

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The shielding connection patterns are positioned specifically in regions where electric field concentration is highest (near the gate oxide interface), providing localized protection where most needed while leaving other channel regions intact for current flow

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20240395927A1Power semiconductor devices including angled gate trenches

Publication Date: 2024.11.28 WOLFSPEED INC

AI summary

A power semiconductor device comprises a semiconductor layer structure comprising a drift region that comprises a wide band-gap semiconductor material that has a first conductivity type, a well region that has a second conductivity type, and a source region that has the first conductivity type in an upper portion of the well region and a gate trench in an upper portion of the semiconductor layer structure and comprising a portion obliquely angled in plan view. Sidewalls of the gate trench may extend along substantially the same crystal plane in the semiconductor layer structure.