Segmented Edge Termination Rings for Electric Field Smoothing
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Solution Overview
Problem
Existing semiconductor switching devices with edge termination structures often experience electric field peaks during the blocking state, leading to reliability failures and insufficient breakdown voltage (VBR).
Innovation Solution
The implementation of an edge termination structure comprising a series of spaced apart concentric ring sections doped with a second type of charge carriers, which smooths out the electric field by distributing the doping profiles laterally and deeper into the semiconductor device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional edge termination structure with wide rings is used, then the breakdown voltage is limited, but the manufacturing process is simpler
Solution Approach 1:
The patent divides the conventional wide ring structure into multiple narrow concentric subrings (3-10 subrings per ring structure). Each subring is doped with the second type of charge carriers and spaced apart by regions doped with the first type of charge carriers. This segmentation creates a more gradual doping profile transition, smoothing the electric field and increasing breakdown voltage from typical conventional values to over 1200V in some embodiments.
Solution Approach 2:
The patent applies different doping concentrations and types at different radial positions within the edge termination structure. The inner regions have different doping profiles compared to outer regions, with the spaced subrings creating localized doping variations. This local quality variation optimizes the electric field distribution at each position, preventing field peaks while maintaining overall high breakdown voltage.
2Reliability
If the doping profile is concentrated in wide rings, then the manufacturing is easier, but electric field peaks occur causing reliability failures
Solution Approach 1:
The doping profile is segmented into multiple discrete doping regions corresponding to the spaced subrings. Each subring region receives a specific doping concentration of the second type of charge carriers, while the spacing regions receive doping of the first type. This segmented doping approach eliminates the harmful concentrated doping peaks of conventional wide rings while maintaining manufacturability through standard ion implantation or diffusion processes applied in sequential steps.
3Reliability
If spaced apart concentric subrings are used to smooth electric field, then breakdown voltage increases, but the device structure becomes more complex
Solution Approach 1:
The patent implements multiple concentric ring structures, each comprising multiple spaced subrings, nested within the semiconductor device's edge termination region. These nested rings with varying doping profiles create a progressive field smoothing effect from the center outward, achieving superior breakdown voltage (>1200V) while containing the structural complexity within a defined radial footprint.
Solution Approach 2:
The patent systematically varies multiple parameters of the ring structure: number of subrings (3-10), lateral width of subrings (3-10 μm), spacing between subrings (4-10 μm), and doping concentrations. By optimizing these parameters, the patent achieves the desired electric field smoothing and breakdown voltage enhancement while managing the structural complexity through standardized geometric parameters that can be manufactured with conventional precision.
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 reduces electric field peaks, thereby enhancing the breakdown voltage (VBR) and improving the reliability of the semiconductor switching device, even under conditions of high humidity and cosmic ray events.
Implementation Method 1
the resulting electric field, which is a function of the doping, is smoothed out to get the advantages of the VLD-like profile within each ring
Data Source
AI summary
A semiconductor switching device implementing an edge termination structure is provided. The present disclosure provides an improved semiconductor switching device with an edge termination structure with an improved VBR and reliability.