SiC Edge Termination Segmentation for Breakdown Voltage
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Solution Overview
Problem
Conventional high-voltage semiconductor devices face limitations in breakdown voltage due to electric field concentration at the edge termination region, leading to potential destruction and restricted switching frequency, especially in power MOSFETs and IGBTs.
Innovation Solution
A semiconductor device design featuring a recessed edge termination region with concentric ring-shaped semiconductor regions of progressively lower impurity concentrations, where the innermost region has the highest impurity concentration and thicker thickness than the first semiconductor region, and a gate insulating film and electrodes configuration to manage the electric field effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional edge termination region is used in high-voltage semiconductor devices, then the device structure is simple, but the breakdown voltage is limited due to electric field concentration at the edge termination region
Solution Approach 1:
The edge termination region is divided into multiple concentric ring-shaped semiconductor regions with progressively lower impurity concentrations. This segmentation distributes the electric field across multiple regions, preventing concentration at any single point and thereby increasing the breakdown voltage of the high-voltage semiconductor device.
Solution Approach 2:
Different impurity concentrations are assigned to different regions within the edge termination region. The innermost region has the highest impurity concentration, while outer regions have progressively lower concentrations. This local variation in impurity concentration optimizes the electric field distribution and enhances breakdown voltage without requiring complex external structures.
2Productivity
If the switching frequency of power MOSFETs and IGBTs is increased, then higher performance is achieved, but the devices are limited by electric field concentration at the edge termination region which causes destruction
Solution Approach 1:
By segmenting the edge termination region into concentric rings with varying impurity concentrations, the electric field is distributed across multiple regions during high-frequency switching operations. This prevents electric field concentration that would otherwise lead to device destruction, enabling reliable high-speed switching.
Solution Approach 2:
The impurity concentration parameter is varied across the edge termination region, with the innermost region having the highest concentration and outer regions having progressively lower concentrations. This parameter variation allows the device to withstand the electrical stresses of high-frequency switching while maintaining stability.
3Stress or pressure
If the breakdown voltage is increased to handle higher electrical loads, then the device can operate at higher voltages, but the edge termination region becomes more susceptible to destruction due to electric field concentration
Solution Approach 1:
The edge termination region is segmented into concentric rings that progressively distribute the electrical load. Each ring handles a portion of the electric field, preventing any single region from experiencing excessive stress that would lead to breakdown or destruction, thereby enabling higher voltage operation with improved reliability.
Solution Approach 2:
The impurity concentration is locally optimized in each concentric ring region, with higher concentrations near the center and lower concentrations toward the periphery. This local quality variation allows the edge termination region to withstand higher electrical loads by distributing the stress across regions with appropriate local properties.
Data Source
AI summary
A recess where an edge termination region is lower than an active region is disposed on a silicon carbide base body and an n−-type silicon carbide layer is exposed at a bottom of the recess. In the portion of the n−-type silicon carbide layer exposed at the bottom of the recess, first and second JTE regions configuring a JTE structure are disposed. The first JTE region is disposed from the bottom of the recess, along a side wall and covers a bottom corner portion of the recess. The first JTE region overlaps an outermost first p-type base region at the bottom corner portion. The first JTE region has an impurity concentration that is highest at the portion overlapping the first p-type base region and distribution of the impurity concentration in a depth direction peaks at a portion deeper than the bottom of the recess.