Superjunction IGBT Carrier Storage and Trench Gate Design
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Solution Overview
Problem
Common superjunction IGBTs face challenges in enhancing minority carrier storage and reducing conduction voltage drop while maintaining high breakdown voltage, due to weak carrier storage effects and potential breakdown of the n region introduced to isolate the p-pillar from the p-type base region.
Innovation Solution
A superjunction IGBT device with a cell structure that includes a voltage sustaining layer, collector structure, base region, and trench gate structures, where the voltage sustaining layer is in indirect contact with the base region via a carrier storage layer, and the trench gate structures provide a carrier path, ensuring a smooth hole path during switching and reducing conduction voltage drop while maintaining high breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If holes are easily collected by the p-pillar and enter the p-type base region, then turn-off speed is increased, but carrier storage effect in the body is weak and conduction voltage drop is high
Solution Approach 1:
The patent segments the hole transport path by introducing the trench gate structure, which divides the direct hole collection path into a controlled multi-stage process. This segmentation allows holes to be transported to the base region (maintaining turn-off speed) while also enabling carrier storage in the body region, thus resolving the contradiction between speed and carrier storage
2Reliability
If the voltage sustaining layer is in indirect contact with the base region via a carrier storage layer, then minority carrier storage is enhanced, but device complexity increases
Solution Approach 1:
The trench gate structure serves multiple functions simultaneously: it provides the carrier path for hole transport, acts as the voltage sustaining layer, and functions as the control electrode. This multi-functionality reduces device complexity while maintaining enhanced minority carrier storage, as one structure performs multiple critical roles
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
The proposed solution enhances minority carrier storage, reduces conduction voltage drop, and provides a reliable switching process with improved breakdown voltage, addressing the limitations of common superjunction IGBTs and p-pillar floating structures.
Implementation Method 1
Superjunction (SJ) is a voltage sustaining structure alternately arranged by an n-pillar/p-pillar, which enables the n-pillar and the p-pillar to still obtain a high breakdown voltage under a high doping concentration
Implementation Method 2
the n-pillar/p-pillar junction can be quickly exhausted during the turn-off process, so that the turn-off speed is increased
Implementation Method 3
holes injected into the n-pillar from the p-type collector region are easily collected by the p-pillar and enter the p-type base region, so that the storage effect of minority carriers in the body
Implementation Method 4
the trench gate structures provide a carrier path, ensuring a smooth hole path during switching
Data Source
AI summary
The disclosure provides a superjunction IGBT (insulated gate bipolar transistor) device, wherein a carrier storage layer of a first conductivity type is provided between a voltage sustaining layer and a base region, and a MISFET (metal-insulator-semiconductor field effect transistor) of a second conductivity type is also integrated in a cell, with at least one gate of the MISFET is connected to the emitter contact thereof. The MISFET is turned off at a low forward conduction voltage, helping to reduce the conduction voltage drop. The MISFET can provide a path for carriers of a second conductivity type and prevent the carrier storage layer from suffering a high electric field when the forward conduction voltage is slightly higher or it is at the forward blocking state, helping to improve the reliability.