SiC Guard Ring Structure With Electric Field Relaxation Layer
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Solution Overview
Problem
Silicon carbide (SiC) semiconductor devices face challenges in maintaining breakdown voltage due to electric field concentration when miniaturization reduces the distance between p-type guard rings, making it difficult to further reduce these distances and prevent breakdown voltage reduction.
Innovation Solution
A silicon carbide semiconductor device structure is developed with a guard ring section and an electric field relaxation layer in the surface layer of the drift layer, extending from the boundary between the mesa and recessed portions, which prevents electric field entry between guard rings, reducing concentration and maintaining breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between p-type guard rings is reduced to enable device miniaturization, then device integration density is improved, but electric field concentration increases causing breakdown voltage reduction
Solution Approach 1:
An n-type intermediate layer is introduced between the p-type guard rings to act as an electric field mediator. This intermediate layer has higher impurity concentration than the drift layer, which allows it to control and redistribute the electric field distribution, preventing direct electric field concentration between the closely spaced guard rings while maintaining miniaturization benefits
Solution Approach 2:
The patent applies local quality by creating regions with different impurity concentrations at specific locations. The n-type intermediate layer is formed only in specific regions between guard rings with higher impurity concentration than the surrounding drift layer, providing localized electric field control exactly where needed without affecting the overall device structure
Data Source
AI summary
In a guard ring section of a silicon carbide semiconductor device, an electric field relaxation layer for relaxing an electric field is formed in a surface layer portion of a drift layer, so that electric field is restricted from penetrating between guard rings. Thus, an electric field concentration is relaxed. Accordingly, a SiC semiconductor device having a required withstand voltage is obtained.