IGBT Semiconductor Element With Segmented Base And Storage Region
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Solution Overview
Problem
IGBTs used in power converters face challenges in achieving low on-resistance and fast switching speed, leading to increased power loss due to high turn-off times.
Innovation Solution
The semiconductor element design includes a semiconductor part with specific electrode configurations and insulating films, allowing for controlled injection and ejection of carriers to reduce on-resistance and turn-off time, featuring a trench gate structure and integrated MOS transistor and diode configurations to minimize manufacturing complexity and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional IGBT structure is used, then breakdown voltage of not less than 600 V is achieved, but on-resistance is high and switching speed is slow
Solution Approach 1:
The semiconductor element is divided into multiple functional layers including emitter region, base region, collector region, and drift region. The base region is further segmented into first and second base regions with different doping concentrations. This segmentation allows each region to be optimized for specific functions, achieving low on-resistance while maintaining high breakdown voltage.
Solution Approach 2:
Different regions of the semiconductor element are assigned different local properties: the emitter region has high doping concentration for low contact resistance, the first base region has moderate doping for carrier injection, the second base region has low doping for high breakdown voltage, and the drift region has graded doping for optimized electric field distribution. This local quality differentiation resolves the contradiction between low on-resistance and high breakdown voltage.
2Strength
If conventional IGBT structure is used, then breakdown voltage of not less than 600 V is achieved, but switching speed is slow due to high turn-off time
Solution Approach 1:
A storage region is formed in the collector region that pre-stores minority carriers before switching operations. During turn-off, these pre-stored carriers are rapidly extracted through the storage region, significantly reducing the turn-off time. This preliminary action of carrier storage and controlled extraction enables fast switching while maintaining high breakdown voltage capability.
Solution Approach 2:
The storage region acts as an intermediary between the collector region and the external circuit during switching operations. It temporarily holds excess carriers and controls their release rate, mediating the transition between on and off states. This intermediary function enables rapid carrier removal during turn-off, improving switching speed without compromising breakdown voltage.
3Loss of energy
If carrier injection is increased to reduce on-resistance, then on-resistance decreases, but turn-off time increases due to excess carrier storage
Solution Approach 1:
The storage region serves as an intermediary that decouples carrier injection from turn-off behavior. During conduction, it accepts and stores excess carriers injected from the emitter, allowing high carrier injection for low on-resistance. During turn-off, it provides a controlled extraction path for rapid carrier removal. This intermediary function resolves the contradiction between low on-resistance and fast turn-off.
Solution Approach 2:
The base region is segmented into first and second base regions with different doping concentrations, creating distinct functional zones. The first base region facilitates efficient carrier injection from the emitter, while the second base region and storage region provide controlled carrier storage and extraction pathways. This segmentation allows independent optimization of injection efficiency and turn-off speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces switching loss by optimizing carrier injection and ejection processes, leading to improved switching speed and reduced power loss in power converters.
Implementation Method 1
The control electrode is electrically insulated from the semiconductor part by a first insulating film and electrically insulated from the first electrode by a second insulating film
Data Source
AI summary
A semiconductor element includes a semiconductor part, first to third electrodes and a control electrode. The first electrode is provided at a front side of the semiconductor part. The second and third electrodes are provided at a back side of the semiconductor part. The control electrode is provided between the semiconductor part and the first electrode. The semiconductor part includes first and third layers of a first conductivity type and second and fourth layers of a second conductivity type. The first layer is provided between the first and second electrodes and between the first and third electrodes. The first layer is connected to the third electrode at the back side. The second layer is provided between the first layer and the first electrode. The third layer is provided between the second layer and the first electrode. The fourth layer is provided between the second electrode and the first layer.