Schottky Rectifier JFET Vertical Inversion Leakage
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Solution Overview
Problem
Modern power circuits require high switching speed and low forward voltage drop, but Schottky barrier rectifiers suffer from high reverse leakage current, especially at elevated temperatures, and conventional trench Schottky rectifiers are not well-suited for low voltage applications due to area reduction and inefficiency.
Innovation Solution
A two-terminal semiconductor device comprising a Schottky barrier rectifier and a vertically-oriented JFET separated by a transition zone of inverted bias resulting from a three-layer epitaxial film, which reduces reverse leakage current and improves chip area utilization by reversing the electric field direction under current blocking bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Schottky barrier rectifiers are used to achieve high switching speed and low forward voltage drop, then switching performance is improved, but reverse leakage current increases at elevated temperatures
Solution Approach 1:
The rectifier structure is segmented into multiple regions including Schottky barrier regions, p/n junction grid regions, and transition zones. This segmentation allows different parts of the device to perform different functions - the Schottky regions provide low forward voltage drop while the p/n junction regions control reverse leakage current, resolving the contradiction between switching speed and reverse leakage.
Solution Approach 2:
Different regions of the rectifier are given different doping concentrations and structural properties. The Schottky barrier regions have specific properties for low forward voltage drop, while the p/n junction regions have properties optimized for reverse leakage control. This local differentiation allows simultaneous optimization of both switching performance and reverse leakage suppression.
2Reliability
If trench Schottky structure is used to improve reverse voltage blocking characteristic, then blocking ability is improved, but chip area available for Schottky barrier is reduced
Solution Approach 1:
The invention transitions from a planar trench structure to a vertically-oriented structure where the p/n junction grid extends in the vertical dimension. This allows the depletion layer to effectively block reverse voltage through vertical field control rather than requiring extensive horizontal trench spacing, thereby maintaining blocking ability while preserving chip area.
Solution Approach 2:
Instead of using trenches to deplete intermediate areas (conventional approach), the invention inverts the approach by using a vertically-oriented p/n junction grid that creates a depletion region extending upward from the substrate, actively controlling the electric field to prevent carrier multiplication and reverse leakage without consuming horizontal chip area.
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 device achieves low forward voltage drop, low reverse current leakage, and fast switching speed, matching the performance of Schottky rectifiers and JFETs while maintaining majority carrier operation, and effectively reduces reverse leakage current more than JBS rectifiers, with improved chip area utilization for low voltage applications.
Implementation Method 1
separated by a transition zone of inverted bias resulting from a three-layer epitaxial film
Implementation Method 2
multi-layer epitaxial film includes three layers
Implementation Method 3
the expanding space charge region from the p+/n junction grid leads to the elimination of the Schottky barrier lowering which is otherwise caused by the resulting image charge
Implementation Method 4
Schottky barrier rectifier
Implementation Method 5
vertically-oriented junction field effect transistor (JFET)
Data Source
AI summary
A rectifier device (10) comprising a multi-layer epitaxial film (12) and a rectifier and a transistor manufactured in the film (12), wherein the transistor is oriented vertically relative to the plane of the rectifier. The rectifier and transistor are separated by a transition zone of inverted bias. The rectifier is a Schottky barrier rectifier, and the transistor is a JFET. More specifically, the device (1) comprises the film (12), a trench (16), a first region (18) associated with an upper portion of the trench (16), and second region (20) associated with a lower portion. The interface between the p+ material of the second region (20) and the n material of the film (12) creates a p+/n junction. The device (10) has use in high frequency, low-loss power circuit applications in which high switching speed and low forward voltage drop are desirable.