Trench Gate IGBT Annular Outer Trenches Breakdown Voltage
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Solution Overview
Problem
In trench gate IGBTs, the curvature radius of the depletion layer at the bottom of the trench can be reduced, leading to a higher electric field concentration at the termination trench, resulting in a lower breakdown voltage and increased on voltage and turn-off loss.
Innovation Solution
The semiconductor device incorporates a trench gate structure with annular outer trenches surrounding the main trenches, where the second gap between the annular outer trenches and the outermost trench is less than the first gap between the main trenches, and the p-type extension region is electrically connected to the emitter electrode, reducing electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the trench gate structure is used to increase channel density, then the on voltage is reduced, but the breakdown voltage is reduced due to electric field concentration at the termination trench
Solution Approach 1:
The patent divides the single termination trench structure into multiple termination trenches arranged in a specific pattern. By segmenting the termination region into multiple trenches, the electric field concentration at any single point is reduced, thereby maintaining high breakdown voltage while preserving the trench gate's low on-voltage characteristics.
Solution Approach 2:
The patent applies different trench configurations to different regions: the termination trenches are specifically arranged with controlled spacing and depths in the termination region, while the active region maintains its trench gate structure. This local differentiation allows optimization of each region's function - low on-voltage in the active region and high breakdown voltage in the termination region.
2Power
If the curvature radius of the depletion layer is reduced to increase channel density, then the on voltage decreases, but the electric field concentration increases leading to lower breakdown voltage
Solution Approach 1:
By introducing multiple termination trenches, the patent segments the electric field distribution in the termination region. This segmentation prevents excessive concentration of electric field lines at any single point, thereby reducing the harmful electric field concentration effect while maintaining the benefits of the trench gate structure.
Solution Approach 2:
The termination trenches act as intermediary structures between the active trench gates and the drift layer termination region. These intermediary trenches provide a gradual transition for the electric field, mediating the field distribution to prevent sharp concentration while allowing the main trench gates to maintain high channel density.
Data Source
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AI summary
A trench gate structure including a p base layer (2), an n+ emitter region (8), a trench (3), a gate oxide film (10), and a doped polysilicon gate electrode (11) is provided in an active region (30). A p-type extension region (C) formed by extending the p base layer (2) to an edge termination structure region (40) is provided in the circumference of a plurality of trenches (3). One or more annular outer trenches (3a) which are formed at the same time as the plurality of trenches (3) are provided in the p-type extension region (C). The annular outer trenches (3a) surround all of the trenches (3). A second gap (b) between the annular outer trench (3a) and the outermost trench (3) or between adjacent annular outer trenches (3a) is less than a first gap (a) between adjacent trenches (3). In this way, it is possible to provide a trench gate insulated gate semiconductor device capable of preventing a reduction in breakdown voltage and improving turn-off breakdown voltage.