SiC Vertical Power Semiconductor Edge Trench for Breakdown Strength
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Solution Overview
Problem
Conventional edge termination structures in silicon carbide semiconductor devices are less effective and more complex to produce due to steeper pn junctions, particularly in materials with small dopant diffusion coefficients, leading to reduced lateral field reduction and increased complexity in voltage blocking capabilities.
Innovation Solution
A vertical power semiconductor device with a silicon carbide semiconductor body featuring trench device cells and an edge termination structure, including a transition area with an edge trench structure that has a larger volume fraction of dielectric material, which mitigates electric field profiles and enhances breakdown strength by equalizing electric fields across the edge termination area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional edge termination structures are used in silicon carbide semiconductor devices, then the device can be manufactured, but the breakdown strength is reduced and the manufacturing complexity increases due to steeper pn junctions
Solution Approach 1:
The edge termination structure is divided into multiple discrete elements: individual trench structures with dielectric material, guard rings with specific doping concentrations, and transition regions. This segmentation allows each component to address specific field control requirements, improving breakdown strength while maintaining manufacturability through modular design
Solution Approach 2:
The patent applies different structural and doping characteristics to different regions: the edge termination area has reduced doping concentrations and specific trench structures, while the active area maintains standard characteristics. This local differentiation optimizes the electric field profile at critical edges without compromising overall device performance
2Object-affected harmful factors
If conventional edge termination structures are used in silicon carbide semiconductor devices, then the device can be manufactured, but the lateral field reduction capability is reduced
Solution Approach 1:
Dielectric material is introduced as an intermediary substance within trench structures at the edge termination region. This dielectric layer mediates the electric field distribution, reducing lateral field crowding by providing electrical isolation and field spreading, thereby improving lateral field reduction capability
Solution Approach 2:
The patent introduces vertical dimensionality through trench structures that extend into the substrate, adding a depth dimension to the traditionally planar edge termination. This three-dimensional approach provides additional space for field control and reduces lateral field strength by distributing the electric field across multiple dimensions
Data Source
Figure 1A~2
Figure 3~4
AI summary
A vertical power semiconductor device (100) is proposed. The vertical power semiconductor device (100) includes a silicon carbide, SiC, semiconductor body (102) including an active area (103) and an edge termination area (104) at least partly surrounding the active area (103). The vertical power semiconductor device (100) further includes a plurality of trench device cells (TC) in the active area (103). Each of the plurality of trench device cells (TC) includes at least one trench structure (106) and a drift region (108) of a first conductivity type. The vertical power semiconductor device (100) further includes an edge termination structure (110) in the edge termination area (104). A transition area (112) is arranged between the active area (103) and the edge termination area (104) along a first lateral direction (x1). The transition area (112) includes an edge trench structure (114) having a larger volume fraction of dielectric material than the at least one trench structure (106).