Trench-Gate IGBT With Segmented Gate Isolation
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Solution Overview
Problem
Current insulated-gate bipolar transistor (IGBT) devices face design trade-offs between improving short circuit withstand time and reducing collector-to-emitter saturation voltage, as well as switching times, due to limitations in front-side carrier injection efficiency and increased input capacitance.
Innovation Solution
The implementation of a three-dimensional IGBT device configuration with defined active and inactive trench segments, increased dielectric thickness, and dielectric isolation between active gate segments, allowing for adjustable front-side injection and reduced gate capacitance, thereby enhancing short circuit capability and switching efficiency without compromising other performance parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If increasing short circuit capability is implemented in current IGBT implementations, then short circuit withstand time is improved, but collector-to-emitter voltage increases and input capacitance increases
Solution Approach 1:
The gate structure is segmented into a first gate segment and a second gate segment separated by a gate isolation region. This segmentation allows independent optimization of different regions: the first gate segment controls carrier injection for low Vce,sat, while the second gate segment provides short circuit withstand capability, resolving the contradiction between these two parameters
2Reliability
If increasing short circuit capability is implemented in current IGBT implementations, then short circuit withstand time is improved, but input capacitance increases leading to increased switching times
Solution Approach 1:
The segmented gate structure with gate isolation region reduces the effective input capacitance by electrically isolating the two gate segments. This allows the device to achieve extended short circuit withstand time through the second gate segment while maintaining fast switching times through reduced capacitance in the first gate segment
3Productivity
If improving switching times and reducing Vce,sat is implemented in current IGBT implementations, then switching efficiency is improved, but short circuit withstand capability deteriorates
Solution Approach 1:
The first gate segment is optimized for fast switching and low Vce,sat through enhanced carrier injection, while the second gate segment is optimized for short circuit withstand capability. The gate isolation region electrically separates these functions, allowing both high switching efficiency and robust short circuit protection to coexist
Data Source
AI summary
In a general aspect, an insulated gate bipolar transistor (IGBT) device can include an active region, an inactive region and a trench extending along a longitudinal axis in the active region. The IGBT device can also include a first mesa defined by a first sidewall of the trench and in parallel with the trench and a second mesa defined by a second sidewall of the trench and in parallel with the trench. The first mesa can include at least one active segment of the IGBT device and the second mesa can include at least one inactive segment of the IGBT device.