SiC Schottky Rectifier Epitaxial Structure for Low Leakage
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Solution Overview
Problem
Schottky barrier rectifiers face high reverse leakage currents when operating at higher temperatures, limiting their use in high-power applications, and replacing silicon with Silicon Carbide increases manufacturing complexity and leakage currents.
Innovation Solution
The development of power semiconductor devices with a substrate and epitaxial layer structure that includes a doped channel, allowing current flow from the substrate through the junction layer to the electrodes, and the method of sequentially stacking silicon carbide sub-epitaxial layers to form a thicker epitaxial layer, reducing leakage current without the need for machining silicon carbide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Schottky barrier rectifiers are used for high switching speeds and low forward bias voltages, then switching performance is improved, but reverse leakage current increases at higher temperatures
Solution Approach 1:
The patent changes the material parameter from silicon to silicon carbide (SiC), which fundamentally alters the temperature-dependent electrical characteristics. SiC's wider bandgap and higher thermal stability enable the rectifier to maintain low reverse leakage current at elevated temperatures while preserving fast switching performance, thus resolving the temperature-dependent leakage problem
2Temperature
If silicon carbide is used as substrate to improve high-temperature resistance, then temperature stability is improved, but manufacturing complexity increases due to brittleness and machining difficulty
Solution Approach 1:
The patent segments the SiC substrate into a mosaic structure composed of multiple smaller SiC pieces arranged in an array. This segmentation reduces the size of individual SiC components, making them easier to handle, process, and assemble while maintaining the overall high-temperature performance benefits of SiC material
Solution Approach 2:
The patent creates a composite structure by combining multiple SiC pieces with intermediate layers or bonding materials to form a mosaic substrate. This composite approach allows the benefits of SiC's high-temperature resistance while mitigating its machining difficulties through the use of more manageable smaller segments
3Duration of action of moving object
If silicon carbide is used as substrate to reduce reverse recovery time, then switching performance is improved, but leakage current in rectifiers increases compared to silicon
Solution Approach 1:
The patent applies different doping concentrations and types in specific regions of the SiC substrate, creating local variations in electrical properties. By optimizing the doping profile in different zones of the mosaic structure, the rectifier achieves low leakage current in critical areas while maintaining fast reverse recovery characteristics in the bulk material
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 solution enables the use of power semiconductor devices in high voltage applications by reducing leakage currents and simplifying the manufacturing process, addressing the limitations of silicon carbide substrates.
Implementation Method 1
The epitaxial layer includes a doped channel located within the peripheral area and extending between the junction layer and the substrate, allowing current to flow from the substrate through the doped channel and the junction layer to the first electrode
Implementation Method 2
forming a first epitaxial sub-layer above a substrate; implanting doping ions into a portion of the first epitaxial sub-layer to create a first doped sub-channel; forming a second epitaxial sub-layer above the first epitaxial sub-layer; implanting doping ions into a portion of the second epitaxial sub-layer to form a second doped sub-channel
Data Source
AI summary
The power semiconductor device comprises a base that includes a substrate and an epitaxial layer located above the substrate, with the base comprising a unit area and a peripheral area surrounding the unit area. A junction layer is located within the peripheral area and above the epitaxial layer. A barrier layer is located within the unit area and above the epitaxial layer. A first electrode is located on the junction layer and a second electrode is located on the barrier layer. The epitaxial layer includes a doped channel located within the peripheral area, extending between the junction layer and the base substrate. Current flows from the substrate through the doped channel and the junction layer to the first electrode.