IGBT Trench Gate Segmentation for Conduction Loss Reduction
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Solution Overview
Problem
Existing power semiconductor devices, such as IGBTs, face challenges in maintaining blocking voltage while reducing conduction loss, as these parameters have a tradeoff relationship, and are prone to latch-up due to their structural limitations.
Innovation Solution
The power semiconductor device incorporates a p-type well and a buried hole accumulation part, along with a well extending portion and a field limiting ring, to reduce conduction loss and prevent latch-up by optimizing the conductivity modulation and electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the IGBT structure is used to reduce conduction loss, then conduction loss is reduced, but blocking voltage cannot be maintained and latch-up occurs
Solution Approach 1:
The device is divided into active region and termination region, with the termination region further segmented into first and second termination regions. The trench gate is segmented to extend only into the first termination region, while the field limiting ring is positioned in the second termination region. This segmentation allows different regions to perform specialized functions: the active region handles conduction, while the termination region with field limiting ring maintains blocking voltage and prevents latch-up.
Solution Approach 2:
Different regions are assigned different doping concentrations and structural characteristics. The field limiting ring in the second termination region has specific doping concentration (1×10^16 to 1×10^18 atoms/cm³) that differs from the active region. The trench gate depth and structure vary between active region and termination region, creating local quality variations that optimize both conduction loss reduction and blocking voltage maintenance in their respective regions.
2Speed
If the trench gate is extended into the termination region, then switching speed is improved, but device complexity increases
Solution Approach 1:
The trench gate extends partially into the termination region (first termination region) but not excessively into the second termination region where the field limiting ring is located. This partial extension is sufficient to improve switching speed by enhancing field control at the active region boundary, while avoiding the complexity of a fully extended trench gate structure that would compromise device reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration achieves a significant reduction in conduction loss by up to 70% and maintains blocking voltage, preventing latch-up by controlling the flow of holes and electric field, thereby enhancing the durability and performance of the device.
Implementation Method 1
A conductivity modulation increasing conductivity in the drift region from tens of times to hundreds of times in response to the high concentration injection of minority carrier is generated.
Implementation Method 2
Electronic current injected into a drift region through a channel induces an injection of hole current from a high-concentration p-type collector layer disposed below the IGBT device, similar to a base current of a bipolar transistor.
Implementation Method 3
a first conductive field limiting ring formed in the second termination region and contacting the well extending portion
Data Source
AI summary
There is provided a power semiconductor device including a contact formed in an active region, a trench gate extendedly formed from the first region into a first termination region and formed alternately with the contact, a first conductive well formed between the contact of the active region and the trench gate, a first conductive well extending portion formed in the first termination region and a part of a second termination region, and a first conductive field limiting ring formed in the second termination region and contacting the well extending portion.