Semiconductor Die Edge Termination for Higher Breakdown Voltage
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Solution Overview
Problem
Existing edge termination structures in semiconductor dies face challenges in efficiently increasing breakdown voltage and dynamically ruggedness, especially at high doping levels and fast transients, due to limitations in potential difference and area utilization.
Innovation Solution
The proposed edge termination structure includes a first inner shield electrode region connected to a well region and an outer shield electrode region, both electrically connected to tap and maintain a potential larger than the active area, allowing for a scalable and efficient use of the edge termination area, thereby increasing breakdown voltage and improving dynamic ruggedness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple laterally staggered shield electrodes with individual well regions are used, then the edge termination structure can provide shielding, but the potential difference between neighbouring shield electrodes decreases towards the lateral edge, limiting the supported breakdown voltage
Solution Approach 1:
Multiple well regions are merged into a single common well region that serves all shield electrodes. This unified well region is electrically connected to a common potential tapping structure, allowing all shield electrodes to operate at optimal potentials simultaneously, thereby maintaining high breakdown voltage without the diminishing returns seen in staggered individual well configurations
Solution Approach 2:
The potential tapping structure extends vertically into the drift region rather than relying solely on lateral well regions at the surface. This vertical dimension allows the shield electrodes to be biased at potentials higher than the frontside surface potential, effectively increasing the breakdown voltage by utilizing the third dimension (depth) rather than being constrained to lateral expansion
2Reliability
If more shield electrodes are added laterally towards the edge, then shielding coverage increases, but the area required for the edge termination structure increases
Solution Approach 1:
The shield electrodes and their associated well regions are arranged in a nested configuration where multiple shielding functions are achieved within a compact lateral footprint. The common well region is shared by multiple shield electrodes, allowing them to be positioned closer together laterally while maintaining effective shielding, thus reducing the total edge termination area required for a given level of dynamic ruggedness
3Device complexity
If shield electrodes are connected to frontside potential regions, then the structure is simple, but the potential difference available for shielding is limited
Solution Approach 1:
The potential tapping structure utilizes the vertical dimension by extending into the drift region beneath the frontside surface. This allows the well region to access potentials that are higher than the frontside surface potential, providing greater voltage headroom for the shield electrodes without adding lateral complexity or requiring additional frontside connections
Data Source
AI summary
A semiconductor die includes a semiconductor device and an edge termination structure laterally between the semiconductor device and a lateral edge of the die. The edge termination structure includes a first inner shield electrode region with a shield electrode in a trench extending into a semiconductor body, an outer shield electrode region with a shield electrode in a trench extending into the semiconductor body and disposed in a first lateral direction between the first inner shield electrode region and the lateral edge, and a well region formed in the semiconductor body adjacent the trench of the first inner shield electrode region. The shield electrode of the first inner shield electrode region is electrically connected to the well region to tap an electrical potential from the well region. The shield electrode of the outer shield electrode region is electrically connected to the shield electrode of the first inner shield electrode region.