IGBT Dummy Cell Segmentation for Hole Accumulation
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Solution Overview
Problem
Conventional insulated gate bipolar transistors (IGBTs) face challenges in achieving high voltage resistance while maintaining low production costs and adequate hole discharge, leading to decreased current density due to reduced main cell area and hole injection efficiency.
Innovation Solution
The design includes a first conductive type drift layer with parallel insulation gates, separated base regions, a high concentration diffusion region, and interlayer insulation films to control hole discharge and accumulation, enhancing conductivity modulation and current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the area ratio of the main cell is decreased to control hole discharge, then hole accumulation is enhanced, but current density decreases
Solution Approach 1:
The invention divides the device structure into functional regions by introducing dummy cells between adjacent main cells. The dummy cells are formed with interlayer insulation films that prevent hole discharge, while main cells maintain their hole discharge function. This segmentation allows the main cell area ratio to be maintained at optimal levels for current density, while the dummy cells provide the necessary hole accumulation control through their insulating structure.
Solution Approach 2:
The dummy cell acts as an intermediary structure between adjacent main cells. It includes an interlayer insulation film that mediates the hole discharge process by blocking holes from reaching the emitter electrode in the dummy cell region, thereby controlling overall hole accumulation without reducing the functional main cell area. This intermediary structure resolves the contradiction by providing hole control functionality without sacrificing current-carrying capacity.
2Reliability
If a thicker drift layer is used to achieve high voltage resistance, then voltage resistance characteristic is improved, but production cost increases
Solution Approach 1:
The invention changes the structural parameters of the drift layer by forming dummy cells with interlayer insulation films at specific regions. Instead of uniformly increasing drift layer thickness across the entire device, the insulation structures are selectively placed in dummy cell regions to provide voltage resistance enhancement only where needed for hole control, while maintaining optimal drift layer thickness in main cell regions for cost-effective manufacturing.
3Reliability
If the emitter region area is reduced to control hole discharge, then hole accumulation is improved, but the device area increases
Solution Approach 1:
The device is segmented into main cells and dummy cells with distinct functions. Main cells have emitter regions optimized for hole discharge and current conduction, while dummy cells contain interlayer insulation films that block hole discharge. This segmentation achieves effective hole discharge control without reducing the area of functional main cells, thereby maintaining high current density without increasing overall device area.
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 effectively enhances hole accumulation and conductivity modulation, maintaining high current density while controlling production costs and improving voltage resistance characteristics.
Implementation Method 1
enhancing hole accumulation effect while controlling decrease in current density
Data Source
AI summary
In some embodiments, an insulated gate bipolar transistor includes a drift layer, insulation gates formed at a principle surface portion of the drift layer, base regions formed in a between-gate region, an emitter region formed in the base region so as to be adjacent to the insulation gate, an emitter electrode connected to the emitter region, a collector layer formed at the other side of the principle surface portion of the drift layer, and a collector electrode connected to the collector layer. The conductive type base regions are separated with each other by the drift layers, and the drift layer and the emitter electrode are insulated by an interlayer insulation film.