SiC Schottky Diode Doping Structure for Lower Voltage Drop
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Solution Overview
Problem
Existing silicon carbide (SiC) switching devices, such as JBS and MPS diodes, face challenges in minimizing voltage drop and conduction losses while maintaining high efficiency, as the reduction of Schottky-Barrier Height (SBH) leads to increased leakage current in reverse biasing.
Innovation Solution
The implementation of a silicon carbide electronic device with a surface portion enriched by doped sub-regions of varying conductivity levels, which extend in succession and are in direct contact with Schottky and ohmic-contact metal portions, reduces the Schottky barrier height and resistance between implanted regions, thereby minimizing voltage drop and conduction losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the Schottky-Barrier Height (SBH) is reduced to minimize voltage drop, then the potential drop decreases, but the leakage current in reverse biasing increases substantially
Solution Approach 1:
The patent applies local quality by creating doped sub-regions with varying conductivity levels (first, second, and third levels) in specific locations between the implanted regions. These localized doped areas modify the electrical properties only where needed, allowing reduction of the Schottky barrier height and voltage drop in the active region while maintaining higher resistance and lower leakage current in other regions through the multi-level doping structure.
2Ease of operation
If N+ surface implant is used to increase surface electrical field and reduce Schottky barrier, then the triggering characteristics improve, but the ON resistance in portions between P implanted regions increases highly
Solution Approach 1:
The patent applies segmentation by dividing the doped region into multiple sub-regions with different conductivity levels (first, second, and third doped sub-regions) rather than using a single uniform N+ implant. This segmented approach allows the surface electrical field to be enhanced for improved triggering characteristics in specific sub-regions while other sub-regions maintain lower resistance through different doping levels, thus resolving the contradiction between triggering performance and ON resistance.
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 the voltage drop and resistance in the JBS device, enhancing its efficiency and performance by carefully managing the Schottky barrier height and surface electrical field.
Implementation Method 1
The surface portion includes a plurality of doped sub-regions, which extend in succession one after another in said direction, each having the first conductivity type and a respective conductivity level higher than that of the bulk portion
Implementation Method 2
Schottky diodes are formed at the interface between the drift layer 2 and the anode metallization 8. In particular, Schottky junctions (i.e., semiconductor-metal junctions) are formed by portions of the drift layer 2 in direct electrical contact with respective portions of the anode metallization 8
Implementation Method 3
an ohmic one in the implanted areas... Ohmic-contact metal portions are on the surface and in direct contact with the first and second implanted regions
Data Source
AI summary
An electronic device includes a solid body of SiC having a surface and having a first conductivity type. A first implanted region and a second implanted region have a second conductivity type and extend into the solid body in a direction starting from the surface and delimit between them a surface portion of the solid body. A Schottky contact is on the surface and in direct contact with the surface portion. Ohmic contacts are on the surface and in direct contact with the first and second implanted regions. The solid body includes an epitaxial layer including the surface portion and a bulk portion. The surface portion houses a plurality of doped sub-regions which extend in succession one after another in the direction, are of the first conductivity type, and have a respective conductivity level higher than that of the bulk portion.