Trench Emitter Structure for Lower Saturation Current in IGBTs
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Solution Overview
Problem
Conventional semiconductor devices, such as IGBTs, face challenges in optimizing the arrangement of conductivity type regions, like emitter and contact regions, which affect their performance characteristics, particularly in current saturation and short-circuit withstand capabilities.
Innovation Solution
The semiconductor device incorporates a low concentration N-type emitter region with a higher resistance, strategically positioned between the emitter electrode and the P-type base region, and a polysilicon resistance portion, to adjust the total emitter width and reduce saturation current, enabling better current handling and voltage management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the emitter region and contact region are arranged in a conventional manner, then the device structure is simple, but the saturation current is high and short-circuit withstand capability is insufficient
Solution Approach 1:
The emitter region is segmented into multiple regions with different conductivity types (first conductivity type and second conductivity type) arranged in an alternating pattern. This segmentation allows different regions to perform different functions: some regions contribute to current conduction while others are designed to be pinned off during short-circuit conditions, thereby improving short-circuit withstand capability without requiring complex external circuitry
Solution Approach 2:
Different regions within the emitter are assigned different local qualities through varying conductivity types. The first conductivity type regions and second conductivity type regions have different electrical properties that are optimized for specific functions. This local differentiation enables certain regions to remain conductive during short-circuit while others become non-conductive, enhancing overall device reliability
2Productivity
If the total emitter width is increased to handle higher current, then current handling capability improves, but saturation current increases and ON voltage rises
Solution Approach 1:
The emitter width is effectively segmented into functional portions through the alternating conductivity type arrangement. During normal operation, the conductive regions carry current, providing high current handling capability. During short-circuit conditions, the pinned-off regions prevent excessive saturation current while the conductive regions maintain low ON voltage, thus resolving the contradiction between current handling and energy loss
Data Source
AI summary
Provided is a semiconductor device including: a semiconductor substrate; gate trench portions; an emitter electrode; a mesa portion; an emitter region of a first conductivity type provided on an upper surface of the mesa portion and in contact with the gate trench portions; a contact region of a second conductivity type provided on the upper surface of the mesa portion; a base region of a second conductivity type provided below the emitter region and the contact region, in contact with the gate trench portions, and having a lower doping concentration than the contact region; a drift region of a first conductivity type provided below the base region and having a lower doping concentration than the emitter region; and a high resistance portion provided between the emitter electrode and the base region in a depth direction of the semiconductor substrate and having a higher resistance than the emitter region.