SiC Edge Termination Doping for Breakdown Voltage Reliability
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Solution Overview
Problem
Power semiconductor devices using silicon carbide (SiC) face issues with depletion regions extending outward due to negative charges at the SiC-oxide interface, leading to concentrated electric fields and reduced reliability, especially in high-temperature applications.
Innovation Solution
The design incorporates a substrate with a semiconductor layer of SiC, featuring a field plate pattern, first and second doped regions of a second conductive type, and a third doped region of the first conductive type, which are strategically positioned and doped to prevent electric field concentration, thereby uniformly distributing termination voltage and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silicon carbide (SiC) is used instead of silicon (Si) to achieve higher breakdown voltage and heat dissipation, then withstand voltage capability and operating temperature are improved, but depletion region extends outward due to negative charges at the SiC-oxide interface causing electric field concentration
Solution Approach 1:
The patent applies local quality by creating a termination region with different doping characteristics from the active region. Specifically, a first termination region is formed with a lower doping concentration than the second termination region, allowing the electric field to be distributed more uniformly across the device structure. This local variation in doping concentration addresses the electric field concentration problem at the SiC-oxide interface while maintaining the high breakdown voltage advantage of SiC material
Solution Approach 2:
The patent changes the doping concentration parameter across different regions of the semiconductor device. By establishing a gradient where the first termination region has lower doping concentration and the second termination region has higher doping concentration, the patent modifies the electrical parameters to control depletion region extension and electric field distribution, thereby preventing electric field concentration while maintaining high withstand voltage capability
2Ease of manufacture
If a termination region is designed in the same manner as conventional silicon devices, then manufacturing simplicity is maintained, but electric field concentration occurs in the last region of the field limiting ring due to negative charges
Solution Approach 1:
The patent divides the termination region into two distinct zones with different doping concentrations. The first termination region adjacent to the active region has a lower doping concentration, while the second termination region has a higher doping concentration. This local differentiation in doping quality allows the device to achieve better electric field distribution without significantly complicating the manufacturing process, as both regions can be formed using standard doping techniques
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 configuration effectively prevents electric field concentration, maintains high withstand voltage, and improves the reliability of power semiconductor devices by uniformly distributing termination voltage, even in high-temperature conditions.
Implementation Method 1
an electric field is concentrated in the last region of a field limiting ring (FLR) due to negative charges, thereby degrading reliability
Implementation Method 2
a first doped region of a second conductive type disposed inside the substrate to extend downward from a top surface of the edge regions
Data Source
AI summary
A power semiconductor device includes a substrate, including an active region and edge regions, including a semiconductor layer of a first conductive type including silicon carbide (SiC); an insulating film disposed on the edge regions; a field plate pattern disposed on the insulating film; a first doped region of a second conductive type disposed inside the substrate to extend downward from a top surface of the edge regions; a second doped region of the second conductive type, buried in the edge regions, extends in a direction having a vector component parallel to the top surface of the substrate; and a third doped region of the first conductive type is disposed on the second doped region and at a side portion of the first doped region.