Semiconductor Device Trench Gate Structure Turn-On Loss
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Solution Overview
Problem
Existing semiconductor devices with trench gate structures face challenges in managing excessive current density and turn-on loss, particularly in preventing electric field concentration and ensuring stable operation at permissible current densities.
Innovation Solution
The semiconductor device incorporates a combination of trench portions, including emitter contact trench portions, emitter non-contact trench portions, and dummy trench portions, which are electrically connected to the gate electrode and emitter electrode, allowing for differential switching times and reduced turn-on loss by utilizing mesa portions with varying switching times to manage current density and prevent electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a dummy trench portion is added adjacent to the first trench portions, then turn-on loss is reduced and current density is controlled, but device complexity increases
Solution Approach 1:
The gate structure is segmented into multiple trench portions with different functions: first trench portions (in contact with emitter region) for primary current control, second trench portions (not in contact with emitter region) for electric field management, and dummy trench portions for additional current density control. This segmentation allows each portion to be optimized independently for its specific function, reducing overall turn-on loss while maintaining manageable complexity through modular design.
Solution Approach 2:
Different trench portions are assigned different electrical connection qualities: first trench portions are electrically connected to the gate electrode and contact the emitter region for direct current control, second trench portions are electrically connected to the gate electrode but do not contact the emitter region for indirect field management, and dummy trench portions are electrically connected to the emitter electrode. This local differentiation of electrical properties enables precise control of current density distribution and turn-on characteristics across different regions of the device.
2Reliability
If multiple trench portions with different electrical connections are used, then current density control is improved, but manufacturing precision requirements increase
Solution Approach 1:
The semiconductor structure is prepared with pre-defined regions (emitter region, contact region) before trench formation. The first trench portions are formed to contact the pre-formed emitter region, while second trench portions are formed to contact the contact region but not the emitter region. This preliminary preparation of the semiconductor structure provides clear geometric references that guide subsequent trench formation, reducing the precision burden on the trench etching process itself.
Solution Approach 2:
The contact region serves as an intermediary element between the emitter region and the second trench portions. By introducing this intermediate structure, the patent decouples the direct contact requirement between second trench portions and emitter region, allowing second trench portions to be formed with relaxed precision tolerances while still achieving the desired electrical isolation from the emitter region through the contact region mediator.
3Object-affected harmful factors
If the second trench portion is electrically connected to the gate electrode but not the emitter region, then electric field concentration is reduced, but device complexity increases
Solution Approach 1:
The second trench portions are extracted from the direct emitter region contact configuration and repositioned to contact only the contact region. This extraction removes the harmful electric field concentration effect that would occur at the trench-emitter region interface, while the trench portions remain electrically connected to the gate electrode to maintain their field management function. The harmful interaction is taken out while preserving the useful electrical connection.
Solution Approach 2:
The patent introduces a vertical dimension of electrical connection control by differentiating which regions each trench portion contacts. First trench portions contact the emitter region at a lower vertical level, while second trench portions contact the contact region at a different vertical level, both while maintaining electrical connection to the gate electrode. This dimensional differentiation in contact configuration allows simultaneous achievement of electric field management and reduced complexity compared to purely horizontal arrangement variations.
Data Source
AI summary
There is provided a semiconductor device including: an emitter region of a first conductivity type, a contact region of a second conductivity type, provided on the front surface side of the semiconductor substrate; one or more first trench portions which are electrically connected to a gate electrode and are in contact with emitter regions; a second trench portion which is adjacent to one of the one or more first trench portions, is electrically connected to the gate electrode, is in contact with the contact region of the second conductivity type, and is not in contact with the emitter region; and a dummy trench portion which is adjacent to one of the one or more first trench portions and is electrically connected to an emitter electrode, in which the contact region in contact with the second trench portion is in contact with the emitter electrode.