SiC Power Device Termination Ruggedness
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Solution Overview
Problem
High voltage silicon carbide (SiC) Schottky-barrier power rectifiers face issues with excessive currents in the termination region under avalanche conditions, which existing solutions are insufficient to address effectively.
Innovation Solution
A silicon carbide (SiC) device with a drift region and a termination region that includes multiple zones with specific doped regions and transition zones, where the transition zones are designed to manage electric field screening and reduce avalanche robustness, featuring a recess and mesa structure to control net charge and electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a termination region is added to the SiC device, then breakdown voltage is improved, but excessive currents occur under avalanche conditions
Solution Approach 1:
The termination region is divided into multiple zones (first zone, second zone, third zone) with different doping concentrations and depths. This segmentation allows each zone to handle different aspects of electric field management, distributing the stress and preventing excessive current concentration that would occur in a uniform structure.
Solution Approach 2:
Each zone in the termination region has locally optimized properties: the first zone has higher doping concentration for electric field screening, the second zone has intermediate properties for transition, and the third zone has lower doping for extended coverage. This local quality optimization ensures that each region performs its specific function to prevent excessive currents while maintaining high breakdown voltage.
2Stability of the object's composition
If transition zones with recesses are created, then electric field distribution is improved, but device complexity increases
Solution Approach 1:
The transition zones incorporate recesses that extend in the depth dimension, creating a three-dimensional structure with varying doping concentrations at different depths. This dimensional approach allows for sophisticated electric field management without requiring complex lateral structures, achieving stable electric field distribution through vertical profiling.
Solution Approach 2:
The termination region structure nests multiple zones within each other, with the first zone containing the recess, the second zone providing intermediate transition, and the third zone extending the protection. This nested arrangement achieves complex electric field control through a hierarchical structure that manages complexity by organizing functions in nested layers.
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 solution effectively reduces leakage currents and enhances avalanche robustness, preventing early destruction and maintaining stable breakdown voltage and on-state voltage under surge conditions, thereby improving the reliability of the SiC device.
Implementation Method 1
The termination zone can have a net charge that is less than a net charge of the first zone, and the termination zone can provide electric field screening
Implementation Method 2
excessive currents can occur in a termination region under avalanche conditions
Data Source
AI summary
In at least one general aspect, a silicon carbide (SiC) device can include a drift region and a termination region at least partially surrounding the SiC device. The termination region can have a first transition zone and a second transition zone. The first transition zone can be disposed between a first zone and a second zone, and the second zone can have a top surface lower in depth than a depth of a top surface of the first zone. The first transition zone can have a recess, and the second transition zone can be disposed between the second zone and a third zone.