Reverse Conducting IGBT Barrier Segmentation
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Solution Overview
Problem
Reverse conducting insulated gate bipolar transistors (IGBTs) experience a two-step ON phenomenon due to parasitic NMOS activation before threshold, leading to malfunction, noise, and erroneous detection, primarily caused by the contact of barrier regions with insulated trench gates, which results in inadequate restriction of hole injection and increased switching loss.
Innovation Solution
The design incorporates a semiconductor layer with a drift region, a body region, and a barrier region, where the barrier region is divided into two partial regions with differing distances from the drift region, and the second barrier partial region is in contact with the insulated trench gate, increasing channel resistance and preventing premature parasitic NMOS activation. Additionally, a high concentration region is introduced under the second barrier partial region to further elevate the threshold value, thereby suppressing the two-step ON phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the barrier region restricts hole injection from the body region, then switching loss reduces, but parasitic NMOS turns on before threshold causing malfunction
Solution Approach 1:
The barrier region is segmented into two partial regions with different positions. The second barrier partial region contacts the insulated trench gate to effectively restrict hole injection and reduce switching loss, while the first barrier partial region is positioned to maintain proper threshold voltage and prevent premature parasitic NMOS activation, thereby avoiding malfunction and noise.
Solution Approach 2:
The barrier region exhibits local quality differentiation where the second barrier partial region is positioned for optimal hole injection restriction to reduce switching loss, while the first barrier partial region is positioned to maintain electrical characteristics that prevent parasitic NMOS turn-on. This local differentiation resolves the contradiction between energy loss reduction and reliable operation.
2Reliability
If the barrier region is positioned closer to the drift region to restrict holes, then reverse recovery improves, but channel resistance decreases causing premature parasitic NMOS activation
Solution Approach 1:
The barrier region is divided into two partial regions with different distances from the drift region. The second barrier partial region contacts the insulated trench gate to improve reverse recovery characteristics, while the first barrier partial region is positioned at an optimized distance to maintain appropriate channel resistance and prevent premature parasitic NMOS activation. This segmentation allows independent optimization of both parameters.
Solution Approach 2:
Different segments of the barrier region are positioned at different distances from the drift region to achieve different local functions. The second barrier partial region provides hole injection restriction for improved reverse recovery, while the first barrier partial region maintains proper channel resistance characteristics. This local quality approach resolves the contradiction between reverse recovery improvement and channel resistance control.
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 configuration effectively represses the two-step ON phenomenon, reduces collector current at initial turn-on, and restricts hole injection, resulting in improved switching characteristics and reduced switching loss without the need for lifetime control on the drift region.
Implementation Method 1
an n-type pillar region 119 extending from a main surface of a semiconductor layer and in Schottky-contact with the emitter electrode 124
Data Source
AI summary
A semiconductor layer of a reverse conducting insulated gate bipolar transistor is provided with a barrier region of the first conductive type, wherein the barrier region is disposed in the body region and electrically connects to the emitter electrode via a pillar member which extends from the one of main surfaces of the semiconductor layer. The barrier region includes a first barrier partial region, wherein a distance between the first barrier partial region and the drift region is a first distance, and a second barrier partial region, wherein a distance between the second barrier partial region and the drift region is a second distance which is longer than the first distance. The second barrier partial region is in contact with a side surface of an insulated trench gate.