Vertical MPS Diode Layout for Low Leakage and Low Resistance
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Solution Overview
Problem
Prior art MPS diodes face a challenge in balancing current leakage in reverse operation and forward resistance, as field relief structures are wide and close together, limiting the available Schottky area.
Innovation Solution
A vertical semiconductor component with a cross-sectional layout where the number of p-doped first regions exceeds the number of p-doped second regions, allowing for a suitable average distance for field relief and carrier injection, thereby increasing the Schottky area while maintaining low leakage and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If field relief structures are made wide and close together to reduce leakage current in reverse operation, then leakage current is reduced, but the available Schottky area is limited
Solution Approach 1:
The field relief structure is segmented into two types of regions: first regions (p-doped at first concentration) that provide field relief to reduce leakage current, and second regions (p-doped at second concentration) that provide low-resistance ohmic contacts. This segmentation allows each region to be optimized for its specific function while working together to reduce the overall footprint of field relief structures, thereby increasing the available Schottky area.
Solution Approach 2:
Different regions within the field relief structure are assigned different doping concentrations to create local quality variations. The first regions have a first doping concentration optimized for field relief, while the second regions have a second doping concentration optimized for low-resistance contacts. This local differentiation enables each area to perform its specific function efficiently, allowing the structure to be more compact and leave more area for Schottky contacts.
2Reliability
If pn-injectors are used to reduce forward resistance at high current densities, then forward resistance is reduced, but the Schottky area is reduced
Solution Approach 1:
The second regions serve multiple functions: they provide low-resistance ohmic contacts for forward conduction at high current densities, and they are embedded within the first regions to maintain the field relief function. This multi-functionality eliminates the need for separate pn-injector structures, thereby preserving Schottky area while achieving low forward resistance.
Solution Approach 2:
The field relief function and the low-resistance contact function are merged into a single integrated structure. The second regions (providing low-resistance contacts) are embedded within the first regions (providing field relief), combining both functionalities into one structure that reduces forward resistance without requiring additional area beyond what is needed for field relief.
3Object-generated harmful factors
If both field relief structures and pn-injectors are implemented to achieve both low leakage and low resistance, then both leakage and resistance are improved, but the remaining Schottky area is significantly reduced
Solution Approach 1:
The field relief structures and pn-injectors are merged into a single integrated structure with two types of regions. The first regions provide field relief to reduce leakage current, while the second regions embedded within them provide low-resistance ohmic contacts to reduce forward resistance. This merging eliminates the need for two separate structures, thereby preserving Schottky area while achieving both low leakage and low resistance.
Solution Approach 2:
The field relief structure is composed of two different doped regions (first regions with first concentration and second regions with second concentration) that work together as a composite structure. This composite approach allows the structure to simultaneously provide field relief and low-resistance contacts, achieving both low leakage and low resistance without requiring the full area of two separate structures.
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 design achieves lower leakage in reverse bias and lower resistance in forward bias, while expanding the available Schottky area, thus optimizing the performance of the semiconductor component.
Implementation Method 1
The leakage current of Schottky diodes in SiC (and in other semiconductors) can be reduced by adding a narrow grid of pn-junctions to the active area. Such a grid reduces the electric field at the Schottky contact in the case of reverse bias.
Implementation Method 2
At high current densities the pn− junctions will be driven in forward mode and will inject minority carries into the bulk. These minority carriers modulate the carrier density thus decreasing the on-resistance.
Data Source
AI summary
A vertical semiconductor component including: a substrate; an epitaxial layer doped with a first conductivity type, preferably n-doped, provided on the substrate; a metal layer deposited on the epitaxial layer to form a Schottky contact with the epitaxial layer; a plurality of first regions embedded in the epitaxial layer and contacting the metal layer, and doped with a second conductivity type, in order to form a plurality of pn-junctions with the epitaxial layer; and a plurality of second regions embedded in a first region and contacting the metal layer, and doped with a second conductivity type, at a higher concentration, in order to form a plurality of low-resistance ohmic contacts with the metal layer. The semiconductor component includes a lateral cross section along which there are more first regions than second regions.