Wide Bandgap Power Device Edge Termination
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Solution Overview
Problem
Current field termination and packaging methods for wide bandgap power electronic devices, such as those using diamond and silicon carbide, limit the voltage blocking capability due to ineffective diffusion of electric fields, leading to compromised current carrying areas and increased risk of surface breakdown.
Innovation Solution
A high voltage device design featuring planar edge termination features, a dual-layer passivation system, and profiled pole pieces to control and diffuse electric fields, ensuring minimal surface breakdown and enhanced insulation performance in a liquid dielectric environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional field termination methods are used, then manufacturing simplicity is maintained, but voltage blocking capability is limited due to ineffective electric field diffusion
Solution Approach 1:
The edge termination region is segmented into multiple functional zones including a first passivation layer with specific dielectric properties, a second passivation layer, and distinct field control electrode regions. This segmentation allows each zone to address specific field diffusion requirements, thereby enhancing voltage blocking capability through controlled electric field distribution.
Solution Approach 2:
Different regions of the device are assigned different material properties and structural characteristics. The passivation layers have specific dielectric constants tailored for field diffusion, while field control electrodes are positioned and dimensioned to create localized field management zones. This local optimization enables effective electric field control without requiring complete redesign of the entire device structure.
2Reliability
If effective electric field diffusion is achieved through advanced termination methods, then surface breakdown risk is reduced, but current carrying area is compromised
Solution Approach 1:
Field control electrodes are positioned in three-dimensional space with specific vertical and radial coordinates, creating field management functionality that extends beyond the traditional planar edge termination. This spatial arrangement enables effective field diffusion while minimizing the lateral footprint that would otherwise reduce current carrying area.
Solution Approach 2:
Passivation layers with specific dielectric properties serve as intermediary materials between the semiconductor edge and the external environment. These layers mediate the electric field distribution, allowing field control electrodes to function effectively while protecting the semiconductor edge, thereby reducing surface breakdown risk without requiring excessive lateral spacing that would reduce current carrying area.
3Reliability
If conventional passivation is used, then manufacturing simplicity is maintained, but insulation performance is insufficient for high voltage applications
Solution Approach 1:
The passivation system employs composite structure with multiple layers having different dielectric properties. The first passivation layer and second passivation layer are composed of materials selected for their complementary electrical and mechanical characteristics, creating a composite structure that achieves superior insulation performance while managing stress and adhesion requirements through material diversity.
Solution Approach 2:
The passivation layers are designed with specific dielectric constant values and thickness parameters optimized for high voltage operation. By controlling the dielectric properties and geometric dimensions of the passivation structure, the system achieves enhanced insulation performance and electric field management capability without requiring fundamentally new manufacturing processes.
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 solution effectively diffuses electric fields, reduces the risk of surface breakdown, and increases the effective current carrying area, thereby enhancing the voltage blocking capability and insulation performance of wide bandgap power electronic devices.
Implementation Method 1
passivation means having a first (or radially inner) part in contact with the edge termination region of the device body and which diffuses the electric field as it emerges from the edge termination region
Implementation Method 2
A high voltage device immersed in a liquid dielectric
Data Source
AI summary
A semiconductor device or power electronic device is described. The device includes a pair of pole pieces, each having a profiled surface. A semiconductor body or wafer, preferably of wide bandgap electronic material, is located between the pole pieces and includes contact metallization regions. The semiconductor body produces an electric field that emerges from an edge region. Passivation means includes a first or radially inner part in contact with the edge region of the semiconductor body and which diffuses the electric field as it emerges from the edge region and a second or radially outer part. The second part of the passivation is in contact with the first part and provides a substantially void-free interface with the profiled surface of each pole piece. The device may be immersed in a dielectric liquid.