High Voltage Termination Structure for Field Balance
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Solution Overview
Problem
Conventional high voltage semiconductor power devices face a tradeoff between drain to source resistance and breakdown voltage, where reducing one parameter often compromises the other, and existing termination structures like buried guard rings and junction termination extensions have limitations such as surface mobile ionic charges and complex manufacturing processes.
Innovation Solution
A termination structure for field balance metal oxide field effect transistors (FBMs) comprising three zones: one to spread the electric field, another to smoothly bring it back to the surface, and a third to prevent body layer shorting, utilizing highly doped and lightly doped epitaxial layers, deep trenches, and buried doped regions, with optional disconnection between buried P-regions and the body region to simplify fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional termination structures like buried guard rings are used, then breakdown voltage is improved, but surface mobile ionic charges occur
Solution Approach 1:
The patent extracts the problematic surface region from the termination structure by implementing a third zone that prevents body layer shorting and stabilizes the electric field at the surface. This separation of functions removes the source of mobile ionic charges while maintaining the voltage blocking capability, thereby improving reliability without introducing surface charge issues.
2Reliability
If junction termination extensions are used, then breakdown voltage is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the functions of multiple termination structures into a single integrated three-zone configuration. Instead of implementing separate buried guard rings and junction termination extensions as conventional approaches do, the invention combines electric field spreading, smooth field transition, and body layer shorting prevention into one unified structure with three doped zones, thereby maintaining high breakdown voltage while simplifying the manufacturing process.
3Ease of manufacture
If a single doped region is used in termination structure, then manufacturing is simplified, but localized breakdowns occur at device edges
Solution Approach 1:
The patent segments the termination structure into three doped zones with different doping concentrations, where each zone addresses specific electrical field distribution challenges. This segmentation prevents localized breakdowns at device edges by creating a controlled gradient in doping concentration, while the overall three-zone architecture remains manufacturable through standard semiconductor fabrication 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
This configuration significantly increases breakdown voltage while minimizing drain to source resistance and reduces localized breakdowns at the device edges, enhancing the overall performance and reproducibility of high voltage semiconductor devices.
Implementation Method 1
one to spread the electric field, another to smoothly bring it back to the surface
Implementation Method 2
deep trenches, and buried doped regions
Data Source
AI summary
The present disclosure describes a termination structure for a high voltage semiconductor transistor device. The termination structure is composed of at least two termination zones and an electrical disconnection between the body layer and the edge of the device. A first zone is configured to spread the electric field within the device. A second zone is configured to smoothly bring the electric field back up to the top surface of the device. The electrical disconnection prevents the device from short circuiting the edge of the device. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.