Shielded-Trench IGBT Body Doping for Lower Turn-Off Loss
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Solution Overview
Problem
IGBT devices experience high turning-off loss due to low hole injection efficiency at the p-type body region and n-type drift region interface, leading to significant tailing turning-off current and increased saturation voltage drop.
Innovation Solution
The IGBT device incorporates a p-type collector region, n-type semiconductor layer, gate trenches with shielded and regular gates, and p-type body regions of varying doping concentrations, where the gate trenches and shielded gates are insulated and isolated, allowing for alternate connection to gate and emitter electrode voltages to manage threshold voltages and charge levels for efficient turn-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the IGBT device uses a conventional structure with uniform doping, then the manufacturing process is simple, but the hole injection efficiency is low and turning-off loss is high
Solution Approach 1:
The p-type body region is divided into multiple regions with different doping concentrations (first p-type body region with lower doping and second p-type body region with higher doping). This segmentation allows different regions to have different functions: the lower-doped region facilitates hole injection and reduces turning-off loss, while the higher-doped region provides structural support and carrier supply, thereby resolving the contradiction between reducing energy loss and maintaining structural simplicity.
Solution Approach 2:
Different regions of the p-type body are given different doping concentrations to optimize local performance. The first p-type body region adjacent to the n-type drift region has lower doping concentration to enhance hole injection efficiency and reduce minority carrier storage, while the second p-type body region has higher doping concentration to maintain structural integrity and provide adequate carrier supply, thus locally optimizing the device to reduce turning-off loss without excessive complexity.
2Strength
If the IGBT device has high hole injection efficiency, then the saturation voltage drop decreases, but the device structure becomes more complex with multiple p-type regions
Solution Approach 1:
The p-type body region is segmented into first and second p-type body regions with different doping concentrations. The first p-type body region with lower doping concentration is positioned adjacent to the n-type drift region to maximize hole injection efficiency, while the second p-type body region with higher doping concentration provides structural support. This segmentation achieves high hole injection efficiency without requiring complete redesign of the entire device structure.
Solution Approach 2:
The doping concentration is locally optimized in different body regions: the first p-type body region has lower doping concentration to enhance hole injection efficiency at the critical interface with the n-type drift region, while the second p-type body region maintains higher doping concentration for structural stability. This local quality differentiation achieves high hole injection efficiency with minimal structural complexity.
Data Source
AI summary
Provided is an IGBT device. The IGBT device includes a p-type collector region, an n-type semiconductor layer located above the p-type collector region, a plurality of gate trenches, shielded gates, gates, and a p-type body region located in the n-type semiconductor layer and between adjacent gate trenches. The gate trenches are located in the n-type semiconductor layer. A shielded gate is located in a lower part of a gate trench. A gate is located in an upper part of the gate trench. The gate, the shielded gate, and the n-type semiconductor layer are insulated and isolated from each other. Partial shielded gates are each externally connected to a gate voltage and are each defined as a first shielded gate. Shielded gates other than the partial shielded gates are each externally connected to an emitter electrode voltage and are each defined as a second shielded gate. The first shielded gate and the second shielded gate are disposed alternately. The p-type body region includes a first p-type body region and a second p-type body region. The first p-type body region is located on a side of the p-type body region close to a first shielded gate adjacent to the p-type body region. The second p-type body region is located on a side of the p-type body region close to a second shielded gate adjacent to the p-type body region. The doping concentration of the first p-type body region is smaller than the doping concentration of the second p-type body region.