SiC Semiconductor Termination with Inclined Side Wall
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Solution Overview
Problem
The existing termination structures in silicon carbide semiconductor devices suffer from high leakage current due to the interface between the silicon carbide substrate and the insulating film, which affects the breakdown voltage and device performance.
Innovation Solution
A silicon carbide semiconductor device with a termination portion featuring a side wall surface inclined between 50° and 80° relative to the {000-1} plane, combined with a specific plane orientation and a side wall impurity region, reduces interface state density and leakage current, while a guard ring region at the bottom surface relaxes electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a termination structure with an insulating film is used to relax the electric field, then the breakdown voltage is improved, but the leakage current increases due to interface states between the silicon carbide substrate and the insulating film
Solution Approach 1:
The invention applies asymmetry by forming a side wall surface with a specific inclination angle (50° to 80° relative to the {000-1} plane) instead of using a conventional vertical or flat surface. This asymmetric geometry reduces the interface state density between the silicon carbide substrate and the insulating film, thereby suppressing leakage current while maintaining the electric field relaxation function for high breakdown voltage
Solution Approach 2:
The invention changes the geometric parameter of the side wall surface inclination angle to a specific range (50° to 80° relative to the {000-1} plane). This parameter optimization minimizes interface state density and leakage current, resolving the contradiction between maintaining high breakdown voltage and reducing harmful leakage current
2Ease of manufacture
If a flat surface is used in the element portion, then the manufacturing process is simplified, but the leakage current increases due to the interface between the substrate and insulating film
Solution Approach 1:
The invention applies local quality by differentiating the surface geometry between the element portion and the termination portion. The element portion maintains a flat surface for manufacturing simplicity, while the termination portion features an inclined side wall surface (50° to 80° relative to the {000-1} plane) to reduce interface states and leakage current, thus achieving both manufacturing ease and low leakage performance
Data Source
AI summary
Each of first to third impurity regions of a silicon carbide substrate has a portion located on a flat surface of a first main surface. On the flat surface, a gate insulating film connects the first and third impurity regions to each other. On the flat surface, a first main electrode is in contact with the third impurity region. A second main electrode is provided on a second main surface. A side wall insulating film covers a side wall surface of the first main surface. The side wall surface is inclined by not less than 50° and not more than 80° relative to a {000-1} plane. In this way, a leakage current is suppressed in a silicon carbide semiconductor device.