IGBT Charge-Ejecting Layer for Fast Turn-Off
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Solution Overview
Problem
Semiconductor devices, such as IGBTs, face a trade-off between low on-resistance and reduced switching loss, where increasing hole density in the n-type base layer leads to longer turn-off times and higher switching losses, and existing gate control methods are constrained by complex circuit designs.
Innovation Solution
The semiconductor device incorporates a p-type charge-ejecting layer between the n-type base layer and the second control electrode, which is electrically isolated, allowing for independent control of the two control electrodes to pre-eject holes and reduce hole density, thereby shortening turn-off times and reducing switching losses by simplifying the gate control circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hole density in the n-type base layer is increased to reduce on-resistance, then on-resistance decreases, but turn-off time increases and switching loss increases
Solution Approach 1:
The gate control electrode is divided into two independent parts: a first control electrode for controlling hole injection and a second control electrode for controlling hole ejection. This segmentation allows independent optimization of turn-on and turn-off processes, enabling low on-resistance during conduction while achieving fast turn-off by pre-ejecting holes before switching off the main gate.
Solution Approach 2:
The second control electrode performs preliminary action by pre-ejecting holes from the n-type base layer before the IGBT is turned off. This preliminary hole ejection reduces the hole density in advance, shortening the turn-off time and reducing switching loss when the main gate is switched off.
2Loss of energy
If two control electrodes are used to pre-eject holes and reduce switching loss, then switching loss decreases, but circuit design complexity increases
Solution Approach 1:
Both control electrodes are integrated into the same trench structure and share common insulating layers and electrical connection paths. This merging of structures allows the complex dual-control function to be implemented with minimal additional circuit complexity, as the two electrodes can be controlled independently while sharing physical infrastructure.
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 reduces the on-resistance and switching losses by promoting hole ejection from the n-type base layer, while simplifying the gate control circuit design and relaxing constraints on voltage drops, thus improving the overall performance of the semiconductor device.
Implementation Method 1
a p-type charge-ejecting layer between the n-type base layer and the second control electrode, which is electrically isolated, allowing for independent control of the two control electrodes to pre-eject holes
Data Source
AI summary
A semiconductor device includes first and second electrodes, a semiconductor part therebetween; first and second control electrodes each in a trench at the frontside of the semiconductor part. The semiconductor part includes first to sixth layers. The first and third layers are of a first conductivity type. Other layers are of a second conductivity type. The first layer extends between the first electrode at the backside and the second electrode at the frontside. The second layer is provided between the first layer and the second electrode. The third and fourth layers each are selectively provided between the second layer and the second electrode. The fifth layer is provided between the first layer and the first electrode. The sixth layer is provided between the first layer and the second control electrode. The sixth layer extends along an insulating film between the semiconductor part and the second control electrode.