Power Schottky Diode Local Current Spreading Layers
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Solution Overview
Problem
Conventional power Schottky diodes face a tradeoff between forward voltage and reverse leakage current, with increased doping concentration in the drift region leading to reduced channel widths and fabrication challenges, making it difficult to consistently produce devices with low reverse leakage current while maintaining desired forward voltage levels.
Innovation Solution
The introduction of local current spreading layers with higher doping concentrations than the drift region, formed underneath and along the sidewalls of blocking junctions, reduces electric field intensity in channels during reverse blocking, allowing for increased channel widths and improved fabrication consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the doping concentration in the drift region is increased to reduce on-state resistance, then the forward voltage is reduced, but the reverse leakage current increases
Solution Approach 1:
The patent applies local quality by creating a current spreading layer with higher doping concentration in specific regions (underneath and adjacent to blocking junctions) rather than uniformly increasing doping throughout the drift region. This localized high-doping approach reduces reverse leakage current at critical areas where electric field crowding occurs, while maintaining lower overall doping to keep on-state resistance low.
Solution Approach 2:
The patent changes the doping concentration parameter by introducing a current spreading layer with doping concentration higher than the drift region. This parameter modification allows the device to achieve lower reverse leakage current while maintaining acceptable forward voltage characteristics, effectively decoupling the tradeoff between these two parameters.
2Manufacturing precision
If the doping concentration in the drift region is increased to reduce channel width, then fabrication precision is improved, but the device complexity increases
Solution Approach 1:
The patent segments the doping structure into distinct regions: a drift region with base doping concentration and a current spreading layer with higher doping concentration. This segmentation allows independent optimization of each region's doping level, simplifying the overall fabrication process while achieving precise channel width control through the blocking junction geometry rather than relying on uniform high doping.
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 approach effectively reduces reverse leakage current while maintaining a desired forward voltage level, enabling consistent fabrication of power Schottky diodes with improved performance and increased channel widths, thus addressing the tradeoff between forward voltage and reverse leakage current.
Implementation Method 1
reduces electric field intensity in channels during reverse blocking
Data Source
AI summary
A Schottky diode includes a drift region doped with dopants having a first conductivity type, first and second blocking junctions that are doped with dopants having a second conductivity type in an upper portion of the drift region, first and second local current spreading layers doped with dopants having the first conductivity type underneath the respective first and second blocking junctions, and first and second contacts on respective lower and upper portions of the drift region. A channel is provided in the upper portion of the drift region between the first and second blocking junctions, the channel doped with dopants having the first conductivity type and a concentration of dopants in at least a first portion of the channel being lower than the concentration of dopants in the first and second local current spreading layers.