SiC Edge Termination with Defect-Enhanced Surface Layer
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Solution Overview
Problem
Silicon carbide devices face challenges with high electrical fields at the semiconductor surface, leading to stress on passivation layers and degradation issues, which affect breakdown behavior and long-term reliability.
Innovation Solution
A silicon carbide device with a buried lateral edge termination region and a transition metal-doped or intrinsic point defect-enhanced surface layer is implemented, reducing electrical fields and protecting the edge termination from degradation, thereby improving breakdown behavior and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional edge termination structure is used in silicon carbide devices, then the device can operate with basic passivation, but very high electrical fields occur at the semiconductor surface leading to stress on passivation layers and degradation
Solution Approach 1:
The edge termination is divided into multiple functional regions: a buried lateral edge termination region (120) for field reduction and a surface layer (130) for protection. This segmentation allows each region to address specific problems - the buried region handles electrical field management while the surface layer provides environmental protection, collectively improving reliability without exposing the buried region to degradation
Solution Approach 2:
The surface layer acts as an intermediary between the buried edge termination region and the external environment. It protects the buried region from oxidation and moisture while allowing the electrical field management function to operate effectively. This intermediary layer resolves the contradiction by shielding the sensitive buried region from harmful environmental factors
2Reliability
If the edge termination region is exposed at the surface for electrical field management, then electrical fields can be controlled, but the region becomes vulnerable to oxidation and degradation
Solution Approach 1:
The surface layer is positioned to cover and protect the buried lateral edge termination region, creating a nested structure where the protective layer encompasses the functional region. This nesting arrangement allows the edge termination to perform its electrical field management function while being shielded from environmental degradation, resolving the contradiction between electrical field control and oxidation resistance
3Reliability
If the buried lateral silicon carbide edge termination region is covered by a silicon carbide surface layer, then protection from degradation and high temperature stability are achieved, but the device structure becomes more complex
Solution Approach 1:
The surface layer is created by modifying the intrinsic properties of the silicon carbide material through transition metal doping or increased density of intrinsic point defects. This parameter change approach allows the use of the same base material (silicon carbide) with different electrical and chemical properties, achieving protection and high temperature stability without introducing foreign materials or complex multi-material structures
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 electrical fields and enhances high-temperature stability and moisture resistance, leading to improved breakdown behavior and long-term reliability of silicon carbide devices.
Implementation Method 1
The silicon carbide surface layer comprises a doping of ions of a transition metal or comprises an increased density of intrinsic point defects in comparison to a density of intrinsic point defects of the buried lateral silicon carbide edge termination region
Implementation Method 2
The silicon carbide surface layer comprises a doping of ions of a transition metal
Implementation Method 3
the increased density of intrinsic point defects is caused by an increased density of carbon vacancy defects
Implementation Method 4
Due to the buried lateral silicon carbide edge termination region, electrical fields occurring during the operation of the silicon carbide device can be reduced towards the edge of the silicon carbide device
Data Source
AI summary
A silicon carbide device includes an epitaxial silicon carbide layer having a first conductivity type and a buried lateral silicon carbide edge termination region within the epitaxial silicon carbide layer and having a second conductivity type. The buried lateral silicon carbide edge termination region is covered by a silicon carbide surface layer including a doping of ions of a transition metal or including an increased density of intrinsic point defects in comparison to a density of intrinsic point defects of the buried lateral silicon carbide edge termination region.