IGBT Sense Diode Layout for Accurate Surge Current Detection

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Solution Overview

Problem

Current semiconductor devices face low current detection accuracy in the sense diode region due to the increased peak surge forward current, which can lead to device breakage.

Innovation Solution

A semiconductor device design where the sense diode region is separated from the IGBT region by a distance equal to or greater than the thickness of the drift layer, preventing current flow through the IGBT region during reflux operations and improving detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the IGBT region area is increased to reduce conduction loss and switching loss, then the power loss is reduced, but the diode region becomes relatively narrow causing peak surge forward current to exceed breakage threshold

Engineering Contradiction:

Improveconduction loss and switching lossVSAvoiddiode region current capacity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent divides the semiconductor device into distinct functional regions: a main IGBT region for power switching, a main diode region for rectification, and a separate sense diode region for current monitoring. This segmentation allows the IGBT region to be optimized for low loss while the sense diode region independently monitors diode current without being constrained by area ratios, preventing overcurrent breakage

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sense diode region acts as an intermediary monitoring system that detects diode current through a sense resistor. Instead of relying on the main diode region to both handle high current and provide accurate current sensing, the sense diode region serves as a separate monitoring channel that provides accurate current detection to prevent overcurrent conditions

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of stationary object

If the sense diode region is positioned close to the IGBT region for compact design, then device area is reduced, but current detection accuracy in the sense diode region deteriorates

Engineering Contradiction:

Improvedevice areaVSAvoidcurrent detection accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The sense diode region is extracted and separated from the IGBT region by a distance of at least the drift layer thickness. This physical separation removes the sense diode region from the high-current IGBT region, eliminating current path interference and ensuring accurate current detection in the sense diode region while maintaining compact overall device design

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20240014206A1Semiconductor device

Publication Date: 2024.01.11 MITSUBISHI ELECTRIC CORP

AI summary

An IGBT region (2) and a diode region (3) are provided on a semiconductor substrate (1) and have an emitter electrode (16) on a surface of the semiconductor substrate (1). A sense IGBT region (4) is provided on the semiconductor substrate (1), has a smaller area than that of the IGBT region (2), and includes a sense emitter electrode (20) provided on the surface of the semiconductor substrate (1) and separated from the emitter electrode (16). A sense diode region (3) is provided on the semiconductor substrate (1), has a smaller area than that of the diode region (3), and includes a sense anode electrode provided on the surface of the semiconductor substrate (1) and separated from the emitter electrode (16). The sense diode region (3) is separated from the IGBT region (2) by a distance equal to or greater than that of the drift layer (8).