Schottky Diode Surface Doping for Lower Leakage and Loss
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Solution Overview
Problem
Schottky diodes using high-power semiconductor materials face a tradeoff between forward-operating characteristics and reverse-bias leakage current, where improving one aspect typically compromises the other, leading to excessive leakage currents at high electric fields.
Innovation Solution
The introduction of shallow surface regions with varying doping concentrations in the drift region of Schottky diodes allows for localized modification of the barrier height and electric field, reducing forward voltage drop and on-state losses without significantly increasing reverse-biased leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the forward voltage drop is reduced to improve forward-operating characteristics, then conduction losses are reduced, but reverse-bias leakage current increases
Solution Approach 1:
The patent applies local quality by introducing localized surface regions with different doping concentrations (first, second, and third surface regions) within the drift region. These regions have distinct electrical properties - the first and second surface regions have higher doping concentrations than the bulk drift region, creating localized variations in barrier height and electric field distribution. This allows different portions of the Schottky contact to have different characteristics, enabling reduced forward voltage drop in certain areas while maintaining reverse blocking capability in others.
Solution Approach 2:
The patent changes the doping concentration parameter by creating multiple regions with different doping levels within the drift region. The first surface region has a first doping concentration, the second surface region has a second doping concentration, and the bulk drift region has a third doping concentration. These parameter variations modify the Schottky barrier characteristics locally, allowing optimization of both forward conduction and reverse blocking properties through controlled doping profile design.
2Object-generated harmful factors
If the reverse-bias leakage current is reduced to improve reverse characteristics, then leakage is reduced, but forward-operating characteristics deteriorate
Solution Approach 1:
The patent uses local quality by creating spatially varying doping concentrations within the drift region. The first and second surface regions with higher doping concentrations create localized potential barriers that reduce leakage current in specific areas, while the overall structure maintains good forward conduction characteristics. This localized modification allows the device to achieve low leakage without sacrificing forward performance.
Solution Approach 2:
The patent segments the drift region into multiple functional zones: a bulk drift region with lower doping concentration for overall device operation, and localized surface regions (first and second surface regions) with higher doping concentrations for specific leakage control functions. This segmentation allows each region to be optimized for its specific purpose, with the surface regions primarily addressing leakage while the bulk region maintains conduction characteristics.
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 enhances the tradeoff between forward and reverse operating characteristics of Schottky diodes, reducing leakage current and on-state conduction losses while maintaining effective reverse blocking capabilities.
Implementation Method 1
a surface region of the first conductivity type disposed in a first portion of the drift region adjacent to the shield region, the surface region having a doping concentration that is greater than a doping concentration of a second portion of the drift region adjacent to the surface region
Implementation Method 2
Schottky diodes utilizing such a power semiconductor materials (e.g., SiC), due to such high electric fields under reverse-biased conditions, can experience leakage currents
Implementation Method 3
a Schottky material disposed on: at least a portion of the shield region; the surface region in the first portion of the drift region; and the second portion of the drift region
Implementation Method 4
Semiconductor materials, e.g., silicon (Si) silicon carbide (SiC), gallium nitride (GaN), etc., used to produce high-power semiconductor devices are subject to the presence of high electric fields during operation of associated semiconductor devices, which can operate at 400 volts (V), 600 V, 1200 V, or higher
Data Source
AI summary
In some aspects, the techniques described herein relate to a diode including: a substrate of a first conductivity type; a semiconductor layer of the first conductivity type disposed on the substrate, the semiconductor layer including a drift region; a shield region of a second conductivity type disposed in the semiconductor layer adjacent to the drift region; a surface region of the first conductivity type disposed in a first portion of the drift region adjacent to the shield region, the surface region having a doping concentration that is greater than a doping concentration of a second portion of the drift region adjacent to the surface region, the second portion of the drift region excluding the surface region; and a Schottky material disposed on: at least a portion of the shield region; the surface region in the first portion of the drift region; and the second portion of the drift region.