Vertical Power Semiconductor Body Contact Segmentation
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Solution Overview
Problem
Vertical power semiconductor devices face reliability challenges when operating under extreme conditions, particularly during high overcurrent turn-off, due to voltage drops and latch-up issues.
Innovation Solution
The design incorporates a body contact structure with strategically positioned sub-regions of higher doping concentration, splitting current paths to reduce voltage drops and enhance latch-up robustness, including a first and second body contact sub-region spaced at a specific lateral distance with a channel region between them, allowing for improved current discharge during high current conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional body contact structure is used, then the device structure is simple, but voltage drops occur and latch-up issues arise under high overcurrent conditions
Solution Approach 1:
The body contact structure is segmented into multiple body contact sub-regions (first body contact sub-region and second body contact sub-region) with different doping concentrations. This segmentation allows different parts of the body contact to serve different functions: one sub-region handles normal current flow while the other sub-region provides latch-up protection during overcurrent conditions, thereby improving device reliability without requiring a completely new structure.
Solution Approach 2:
Different body contact sub-regions are assigned different doping concentrations tailored to their specific functional requirements. The first body contact sub-region has a doping concentration optimized for low on-state resistance during normal operation, while the second body contact sub-region has a different doping concentration optimized for latch-up protection during overcurrent events. This local differentiation of properties enables the structure to address multiple concerns simultaneously.
2Loss of energy
If the first lateral distance between body contact sub-regions is reduced, then voltage drops are reduced, but the channel region distance to gate trench structure must be maintained
Solution Approach 1:
The patent defines specific geometric relationships between body contact sub-regions and the gate trench structure in multiple dimensions. The first lateral distance (along the first lateral direction) and second lateral distance (along the second lateral direction perpendicular to the first) create a two-dimensional positioning system. This dimensional approach allows optimization of voltage drop (by controlling first lateral distance) while maintaining proper channel region spacing (by controlling second lateral distance), balancing electrical performance with manufacturing feasibility.
Data Source
AI summary
A vertical power semiconductor device includes a semiconductor body having opposing first and second main surfaces. At least part of a gate trench structure formed at the first main surface extends along a first lateral direction. Body and source regions directly adjoin the gate trench structure. A drift region is arranged between the body region and second main surface. A body contact structure includes first and second body contact sub-regions spaced at a first lateral distance along the first lateral direction. Each body contact sub-region directly adjoins the gate trench structure and has a larger doping concentration than the body region. In a channel region between the body contact sub-regions, the body contact structure has a second lateral distance to the gate trench structure along a second lateral direction perpendicular to the first lateral direction. The first lateral distance is equal to or less than twice the second lateral distance.