SiC MPS Diode Structure for Avalanche Robustness and Low Recombination
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Solution Overview
Problem
Existing SiC semiconductor components face challenges in improving avalanche robustness, breakdown strength, and on resistance, particularly due to the limitations of intrinsic body diodes in field effect transistor structures, which affect the long-term stability and reliability of the components.
Innovation Solution
The introduction of a zone of specific conductivity type, strategically positioned between the semiconductor region and the drift zone, with a dopant concentration at least double that of the drift zone, reduces emitter efficiency and hole injection, thereby minimizing recombination and crystal defect formation, and enhances avalanche behavior by steepening the electrical field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping and dimensions of doped regions are optimized for transistor properties, then transistor performance is improved, but the emitter efficiency and hole injection of the body diode increase, leading to increased recombination and crystal defect formation
Solution Approach 1:
The patent introduces a specifically doped zone between the semiconductor region and drift zone with doping concentration and dimensions optimized locally to reduce hole injection and recombination, while maintaining transistor performance in other regions
Solution Approach 2:
The specially designed zone acts as an intermediary structure between the semiconductor region and drift zone, mediating the charge carrier flow to reduce harmful recombination effects while maintaining electrical connectivity
2Quantity of substance
If the body diode is operated in forward direction with bipolar charge carrier flow, then current-carrying capacity is improved, but recombination and crystal defect formation increase, reducing avalanche robustness
Solution Approach 1:
The patent creates a localized zone with specific doping characteristics that manages charge carrier flow during forward operation, allowing high current capacity while controlling recombination to maintain avalanche robustness
3Strength
If the doping concentration in the drift zone is increased to improve breakdown strength, then dielectric strength is improved, but the on resistance increases
Solution Approach 1:
The patent optimizes the doping concentration parameter in the drift zone to achieve the right balance between breakdown strength and on resistance, using a zone with at least double the doping concentration of the drift zone to manage charge carrier flow and reduce harmful effects
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 solution effectively reduces the emitter efficiency of intrinsic body diodes, improves avalanche robustness, and maintains long-term stability of SiC semiconductor components by minimizing charge carrier recombination and crystal defect growth, while maintaining acceptable forward voltage and on resistance.
Implementation Method 1
A recombination zone having recombination centres composed of lattice defects and/or heavy metal atoms is formed between the doped region and a second surface situated opposite the first surface
Implementation Method 2
enhances avalanche behavior by steepening the electrical field
Data Source
AI summary
A semiconductor component includes a semiconductor component, including: a merged PiN Schottky (MPS) diode structure in a SiC semiconductor body having a drift zone of a first conductivity type; an injection region of a second conductivity type adjoining a first surface of the SiC semiconductor body; a contact structure at the first surface, the contact structure forming a Schottky contact with the drift zone and electrically contacting the injection region; and a zone of the first conductivity type formed between the injection region and a second surface of the SiC semiconductor body, the second surface being situated opposite the first surface. The zone is at a maximal distance of 1 μm from the injection region of the second conductivity type.