Trench-Gate IGBT Segmented Gate Structure for Short Circuit Withstand
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Solution Overview
Problem
Current insulated-gate bipolar transistor (IGBT) devices face a trade-off between short circuit withstand time and collector-to-emitter saturation voltage, where improving one parameter often degrades another, limiting their performance in high voltage applications such as motor drives and power factor correction systems.
Innovation Solution
The approach involves defining active and inactive trench segments with increased dielectric thickness and dielectric isolation, allowing for adjustable front-side injection and reduced gate capacitance, which enhances short circuit withstand time without significantly impacting other performance parameters like collector-to-emitter saturation voltage and switching times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If short circuit capability is increased, then short circuit withstand time is improved, but collector-to-emitter voltage increases and input capacitance increases leading to slower switching times
Solution Approach 1:
The gate structure is segmented into active gate segments and inactive gate segments. The active segments control carrier injection for normal operation, while inactive segments (filled with dielectric material) provide shielding and reduce capacitance. This segmentation allows the device to achieve improved short circuit withstand capability through the inactive segments without sacrificing switching speed, as the active segments remain optimized for fast switching.
Solution Approach 2:
Different regions of the gate structure are assigned different properties: active gate segments have conductive material for carrier control, while inactive gate segments have dielectric material for capacitance reduction and shielding. This local differentiation allows simultaneous optimization of short circuit capability (through inactive segments providing shielding) and switching speed (through active segments maintaining low capacitance).
2Reliability
If short circuit capability is increased, then short circuit withstand time is improved, but collector-to-emitter saturation voltage increases
Solution Approach 1:
The gate is divided into active and inactive segments. The inactive segments filled with dielectric material provide shielding that improves short circuit withstand capability without requiring increases in device dimensions that would raise saturation voltage. The active segments maintain optimized doping and geometry for low saturation voltage operation.
Solution Approach 2:
Dielectric material is introduced as an intermediary in the inactive gate segments. This dielectric layer provides electrical shielding during short circuit conditions, enhancing withstand capability without the need to increase collector or emitter dimensions, thereby avoiding increases in saturation voltage.
3Reliability
If device dimensions are increased to improve short circuit capability, then short circuit withstand time is improved, but device area increases
Solution Approach 1:
The gate structure is segmented into active and inactive portions. The inactive segments (filled with dielectric) provide short circuit shielding without requiring proportional increases in active device area. This allows short circuit capability enhancement with minimal impact on overall device footprint, as the inactive segments utilize space that would otherwise be active gate material.
Solution Approach 2:
The inactive gate segments serve multiple functions: they provide shielding for short circuit capability, reduce input capacitance, and maintain device compactness. This multi-functionality allows simultaneous improvement of short circuit withstand time without proportionally increasing device area.
Data Source
AI summary
In a general aspect, method of producing an insulated-gate bipolar transistor (IGBT) device can include forming a termination structure in an inactive region. The inactive region at least partial surround an active region. The method can also include forming a trench extending along a longitudinal axis in the active region. A first mesa can define a first sidewall of the trench, and a second mesa can define a second sidewall of the trench. The first mesa and the second mesa can be parallel with the trench. The method can further include forming, in at least a portion of the first mesa, an active segment of the IGBT device, and, forming, in at least a portion of the second mesa, an inactive segment of the IGBT device.