Super-Junction Edge Termination Layout for Reverse-Bias Field Control
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Solution Overview
Problem
Wide bandgap semiconductor devices, such as SiC-SJ devices, experience significantly higher electric fields under reverse bias, necessitating effective edge termination designs to ensure reliable and robust device operation.
Innovation Solution
A multi-layered edge termination design for SJ devices is implemented using repeated epitaxial growth and dopant implantation steps, featuring vertical pillars of alternating conductivity types with decreasing widths and increasing separation by low-doped regions, allowing for effective electric field reshaping and robust edge termination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wide bandgap semiconductor devices are used for high-voltage applications, then temperature stability and reduced on-state resistance are improved, but significantly higher electric fields are generated under reverse bias requiring complex edge termination designs
Solution Approach 1:
The termination region is segmented into multiple alternating layers of first and second conductivity types, creating a multi-layered structure that distributes and controls the electric field. This segmentation allows the high electric fields to be managed through the layered architecture rather than requiring a single complex termination design.
Solution Approach 2:
The patent implements local quality by creating regions with different doping concentrations and conductivity types at specific locations. The alternating conductivity types in the termination region provide locally optimized electric field control, with each layer tailored to manage the electric field distribution in its specific zone.
2Reliability
If vertical pillars with decreasing widths are implemented in the termination region, then electric field peaks are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The termination region employs periodic alternating layers of first and second conductivity types with regular patterns. This periodic structure creates predictable electric field distribution that reduces peak fields while maintaining manufacturability through consistent, repeating patterns rather than irregular variable geometries.
Solution Approach 2:
The patent utilizes parameter changes by varying the doping concentration and conductivity type across multiple layers. Instead of relying solely on gradual width reduction of pillars, the invention changes electrical parameters (doping concentration, conductivity type) to achieve electric field control, reducing the precision requirements for geometric dimensions.
3Reliability
If alternating conductivity type layers are used in the termination region, then electric field distribution is improved, but device pitch size increases
Solution Approach 1:
The patent addresses the pitch size issue by transitioning to a multi-layered vertical structure. Instead of expanding horizontally with larger pillars, the invention stacks alternating conductivity layers in the vertical dimension, achieving effective edge termination through the third dimension while maintaining compact planar footprints.
Solution Approach 2:
The termination region functions as a composite structure with alternating layers of different conductivity types. This composite architecture combines the benefits of both n-type and p-type regions in a stacked configuration, achieving superior electric field control without requiring increased lateral dimensions.
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
The design achieves reduced electric field peaks and smaller cell pitch sizes, enhancing device performance and reliability by minimizing process variations and maintaining effective edge termination.
Implementation Method 1
significantly higher electric fields present in wide bandgap semiconductors devices under reverse bias
Implementation Method 2
super-junction (SJ) (also referred to as vertical charge-balance) designs
Implementation Method 3
repeated epitaxial growth and dopant implantation steps
Implementation Method 4
repeated epitaxial growth and dopant implantation steps
Data Source
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AI summary
The subject matter disclosed herein relates to super-junction (SJ) power devices and, more specifically, to edge termination techniques for SJ power devices. A semiconductor super-junction (SJ) device includes one or more epitaxial (epi) layers having a termination region disposed adjacent to an active region. The termination region includes a plurality of vertical pillars of a first and a second conductivity-type, wherein, moving outward from the active region, a respective width of each successive vertical pillar is the same or smaller. The termination region also includes a plurality of compensated regions having a low doping concentration disposed directly between a first side of each vertical pillar of the first conductivity-type and a first side of each vertical pillar of the second conductivity-type, wherein, moving outward from the active region, a respective width of each successive compensated region is the same or greater.