Bipolar Power Semiconductor Device with Horizontal Superjunction
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Solution Overview
Problem
Conventional trench emitter switched thyristors (EST) and trench insulated gate bipolar transistors (IGBTs) face a trade-off between on-state voltage and collector current saturation, limiting their performance and avalanche capability.
Innovation Solution
A bipolar power semiconductor device with a horizontal superjunction structure, featuring alternately doped enhancement and well layers, which allows for increased doping concentrations without premature breakdown, enabling low on-state voltage and high collector current saturation, and incorporating additional enhancement and well layers to enhance carrier spreading and reduce switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the doping concentration of the enhancement layer is increased to reduce on-state voltage, then the on-state voltage decreases, but the device experiences premature breakdown and loses avalanche capability
Solution Approach 1:
The enhancement layer is segmented into multiple alternating layers with different doping concentrations (first enhancement layer with higher doping, second enhancement layer with lower doping). This segmentation allows the device to achieve low on-state voltage through the highly doped first enhancement layer while the lower doped second enhancement layer prevents premature breakdown and maintains avalanche capability.
Solution Approach 2:
Different regions of the enhancement layer are assigned different doping concentrations to perform different functions. The first enhancement layer region has high doping concentration optimized for reducing on-state voltage, while the second enhancement layer region has lower doping concentration optimized for maintaining breakdown voltage and avalanche capability. This local quality differentiation resolves the contradiction between low on-state voltage and high reliability.
2Device complexity
If a conventional single-layer enhancement structure is used, then the device structure is simple, but carrier spreading is insufficient and switching losses are high
Solution Approach 1:
The enhancement layer is divided into multiple alternating layers (first and second enhancement layers) with different doping concentrations. This segmentation improves carrier spreading by creating multiple interfaces and regions for carrier generation and transport, thereby reducing switching losses despite the increased structural complexity.
Solution Approach 2:
The enhancement layer is constructed as a composite structure with alternating regions of high and low doping concentrations. This composite approach combines the benefits of high doping (good carrier injection and low on-state voltage) with low doping (good carrier spreading and reduced switching losses), achieving superior overall performance.
Data Source
AI summary
A bipolar power semiconductor device is provided with an emitter electrode on an emitter side and a collector electrode on a collector side. The device has a trench gate electrode and a structure with a plurality of layers of different conductivity types in the following order: at least one n doped source region, a p doped base layer, which surrounds the at least one source region, an n doped enhancement layer, a p doped additional well layer, an additional n doped enhancement layer, an additional p doped well layer, an n doped drift layer and a p doped collector layer. The trench gate electrode has a gate bottom, which is located closer to the collector side than the additional enhancement layer bottom.