Power Device FBSOA via Segmented Source Threshold Voltages

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Solution Overview

Problem

It is challenging to improve the Forward Biased Safe Operating Area (FBSOA) of power semiconductor devices without significantly increasing the drain-to-source resistance (RDS(on)), as FBSOA is limited by thermal instability and conflicting requirements for transconductance and RDS(on) in power devices.

Innovation Solution

The implementation of power devices with multiple threshold voltage source segments, where the source segments are energized under different operating conditions, improves FBSOA with only a minimal increase in RDS(on), achieved by distributing low and high threshold voltage source segments uniformly throughout the power device die.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If power devices operate with increased FBSOA, then thermal stability and operational safety are improved, but device breakdown risk increases due to localized heating and excessive voltage/current application

Engineering Contradiction:

ImproveFBSOAVSAvoidlocalized heating

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The source region is divided into multiple segments with different threshold voltages (first source segments with first threshold voltage, second source segments with second threshold voltage). This segmentation allows different portions of the device to operate at different current densities, distributing the power dissipation and reducing localized heating while expanding the overall FBSOA.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different source segments are assigned different threshold voltages to create local variations in electrical characteristics. The first source segments with first threshold voltage and second source segments with second threshold voltage provide spatially differentiated current conduction, enabling regions with different thermal characteristics to be optimized independently.

Inventive Principle:

Principle #3Local quality

2Reliability

If power devices use segmented sources with different threshold voltages, then FBSOA is increased, but device complexity increases

Engineering Contradiction:

ImproveFBSOAVSAvoidsource segmentation

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The source is segmented into first source segments and second source segments with different threshold voltages, arranged in a systematic pattern across the device. This segmentation is integrated into the device fabrication process, creating a structured complexity that manages to improve FBSOA while maintaining manufacturability.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10998403B2Device with increased forward biased safe operating area (FBSOA) through using source segments having different threshold voltages

Publication Date: 2021.05.04 INFINEON TECHNOLOGIES AMERICAS CORP

AI summary

A power device includes a gate, and a segmented source adjacent to the gate, wherein the segmented source includes segments having a first threshold voltage and includes segments having a second threshold voltage different from the first threshold voltage.