SiC Edge Termination Rings for Electric Field Peak Reduction
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Solution Overview
Problem
Existing edge termination structures for silicon carbide integrated power devices face limitations in achieving high breakdown voltages due to electric field peaks caused by the potential lines crowding effect, leading to premature aging and reliability issues, which are not effectively addressed by existing techniques adapted from silicon-based technologies.
Innovation Solution
The proposed integrated device features a ring-shaped edge termination structure with concentric ring structures and transition regions, where connection regions of one conductivity type are alternated with charge control regions of another conductivity type, reducing electric field peaks by controlling charge density and approximating a continuous degrading profile compatible with lithographic techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional edge termination structures are used in silicon carbide devices, then manufacturing is simplified, but electric field peaks occur at ring boundaries causing premature aging and reliability issues
Solution Approach 1:
The edge termination structure is divided into multiple concentric ring structures with alternating conductivity types. Each ring serves as a separate segment that collectively manages the electric field distribution, preventing concentration at any single boundary while maintaining manufacturing feasibility through modular design
Solution Approach 2:
Different regions of the edge termination structure are assigned different conductivity types (first and second conductivity types) to create locally optimized electric field management. The alternating pattern ensures that each local region has appropriate charge characteristics to control the electric field, preventing peaks while adapting to the specific geometric constraints of that region
2Manufacturing precision
If single mask and single dopant implant are used to form ring region, then manufacturing is simplified, but electric field distribution cannot be accurately controlled
Solution Approach 1:
The dopant implantation process is segmented into multiple sequential implants, each targeting specific ring structures with alternating conductivity types. This allows precise control over the electric field distribution by independently adjusting the depth, concentration, and pattern of each implant while maintaining a systematic manufacturing approach
Solution Approach 2:
Multiple masks are prepared and applied in sequence before the actual dopant implantation. Each mask is designed in advance to define the specific pattern for a particular ring structure, allowing the electric field distribution to be pre-planned and accurately controlled before the implantation process begins
3Reliability
If successive implants with decreasing depth are used to form stepped profile, then electric field control is improved, but electric field peaks at transitions cause stress in surface oxides
Solution Approach 1:
The transition regions between rings of different depths are locally optimized by alternating conductivity types. This creates a graded electric field distribution that smoothly transitions between different depth levels, eliminating sharp peaks that would cause oxide stress while maintaining the stepped profile necessary for effective electric field control
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 solution effectively reduces electric field peaks at the interfaces between ring structures, minimizing stress on materials and preventing premature aging, thereby enhancing the reliability of silicon carbide integrated power devices.
Implementation Method 1
connection regions, having the second conductivity type, connected to the second one of the ring structures and alternated with charge control regions having the first conductivity type... reducing electric field peaks by controlling charge density
Data Source
AI summary
An integrated device includes: a semiconductor structural layer, including silicon carbide and having a first conductivity type; a power device integrated in the structural layer; and an edge termination structure, extending in a ring around the power device and having a second conductivity type. The edge termination structure includes a plurality of ring structures each arranged around the power device and in contiguous pairs. At least a first one of the ring structures comprises a transition region contiguous to a second one of the ring structures. The transition region includes connection regions, having the second conductivity type, connected to the second one of the ring structures and alternating with charge control regions having the first conductivity type.