SiC Edge-Termination Structure for Breakdown Prevention
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Solution Overview
Problem
Integrated electronic devices, particularly those with silicon carbide components, face breakdown issues due to intense electrical fields in peripheral regions lacking effective edge-termination structures, which restrict the maximum voltage that can be applied and lead to device failure.
Innovation Solution
A vertical-conduction integrated electronic device with a trench MOSFET structure and a buried edge-termination structure, featuring semiconductor regions and dielectric layers that reduce electrical fields in peripheral regions, preventing breakdown by confining equipotential lines and electrical fields within the edge-termination structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no edge-termination structure is provided in peripheral regions, then device structure is simpler, but breakdown occurs at low voltages due to intense electrical fields
Solution Approach 1:
The device is divided into central regions containing active components and peripheral regions with edge-termination structures. This segmentation allows different regions to have optimized structures for their specific functions, with the peripheral regions containing termination structures that prevent breakdown while the central regions maintain simple active component designs.
Solution Approach 2:
Edge-termination structures act as intermediary elements between the active areas and the device edges. These structures include specially designed doped regions and insulation layers that mediate the electrical field distribution, preventing direct field concentration at the edges while maintaining overall device functionality.
2Reliability
If edge-termination structures are added to prevent breakdown, then breakdown voltage increases, but manufacturing process becomes more complex
Solution Approach 1:
The edge-termination structures are merged with the existing device fabrication process. The termination structures share common manufacturing steps with the active components, such as using the same doping processes, insulation layer deposition, and etching techniques, thereby reducing overall manufacturing complexity despite adding functional elements.
Solution Approach 2:
The edge-termination structures are formed during the preliminary stages of device fabrication, before the active components are fully assembled. By preparing the peripheral regions in advance with appropriate doping and insulation, the subsequent assembly of active components becomes simpler and more straightforward.
3Device complexity
If intense electrical fields are allowed in peripheral regions, then device design is simpler, but electrical breakdown occurs limiting maximum voltage
Solution Approach 1:
Different regions of the device are given different structural qualities optimized for their specific functions. The central regions have simple structures suitable for active components, while the peripheral regions have enhanced structures with edge-termination features that specifically address the electrical field management requirements of boundary areas.
Solution Approach 2:
The edge-termination structures extend the device functionality into the peripheral dimension, utilizing the space around the active components for field management. By adding vertical insulation layers and adjusting doping profiles in the peripheral regions, the solution addresses electrical field issues in a third dimension rather than complicating the planar active component design.
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 prevents breakdown in peripheral regions, allowing for higher voltage application without device failure, leveraging the higher critical electrical field of silicon carbide while minimizing electrical fields in the top epitaxial layer, thus enhancing the device's operational reliability.
Implementation Method 1
silicon carbide, which has a critical electrical field higher than the critical electrical field of silicon
Implementation Method 2
the edge-termination structures hence perform the function of reducing locally the intensity of the electrical field so as to prevent peaks of intensity of the electrical field in the proximity of the edges
Data Source
AI summary
An embodiment of an integrated electronic device formed in a semiconductor body delimited by a lateral surface, which includes: a substrate made of a first semiconductor material; a first epitaxial region made of a second semiconductor material, which overlies the substrate and defines a first surface; a second epitaxial region made of a third semiconductor material, which overlies the first surface and is in contact with the first epitaxial region, the third semiconductor material having a bandgap narrower than the bandgap of the second semiconductor material; an active area, extending within the second epitaxial region and housing at least one elementary electronic component; and an edge structure, arranged between the active area and the lateral surface, and including a dielectric region arranged laterally with respect to the second epitaxial region, which overlies the first surface and is in contact with the first epitaxial region.