SiC JBS Diode Grid Doping for Lower High-dV/dt Switching Loss
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Solution Overview
Problem
High voltage silicon carbide (SiC) Schottky diodes face catastrophic failure and high reverse leakage currents due to uneven depletion region spreading, leading to significant power switching losses during high dV/dt transitions, especially in high voltage unipolar devices like 10 kV SiC MOSFET and JBS diodes.
Innovation Solution
Increasing the dopant concentration in the grid regions of the JBS diode to reduce the resistance of the grid, combined with using metals like titanium, tungsten, and tantalum for the contact metallization layer, to minimize power losses during high dV/dt transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional doping levels are used in JBS diodes, then the device structure is simpler and manufacturing is easier, but the resistance is higher causing significant power switching losses during high dV/dt transitions
Solution Approach 1:
The patent applies parameter changes by increasing the dopant concentration in the grid regions from conventional levels to greater than 2.2×10^19 atoms/cm³. This parameter modification directly reduces the resistance of the grid regions, thereby reducing power switching losses during high dV/dt transitions by up to three times compared to conventional devices.
2Loss of energy
If higher dopant concentration is used in grid regions, then resistance is reduced and switching losses are minimized, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a precise dopant concentration range (>2.2×10^19 atoms/cm³) to optimize the balance between reducing switching losses and maintaining manufacturability. This parameter setting achieves significant loss reduction while establishing clear manufacturing specifications for controlling dopant concentration.
3Loss of energy
If conventional metallization is used, then manufacturing is easier, but power losses during high dV/dt transitions are significant
Solution Approach 1:
The patent changes the material parameter of the metallization layer by selecting metals with higher conductivity (titanium, tungsten, tantalum) compared to conventional metallization. This material substitution reduces power losses during high dV/dt transitions while maintaining reasonable manufacturing complexity through standard deposition processes.
4Loss of energy
If increased dopant concentration is applied, then switching losses are reduced, but the device may become more sensitive to defects and reliability issues
Solution Approach 1:
The patent applies local quality by selectively increasing dopant concentration only in the grid regions where it is most needed for reducing switching losses during high dV/dt transitions. The drift region maintains its standard doping profile for voltage blocking, while the grid regions receive enhanced doping (>2.2×10^19 atoms/cm³). This localized approach minimizes the impact on overall device reliability while achieving the desired loss reduction.
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 increased dopant concentration and specific metallization reduce power losses by minimizing displacement currents, achieving switching losses less than 450 μJ and charge losses less than 120 nC, even at high voltage transitions, without being associated with diode junction capacitance.
Implementation Method 1
Increasing the dopant concentration in the grid regions of the JBS diode to reduce the resistance of the grid
Implementation Method 2
using metals like titanium, tungsten, and tantalum for the contact metallization layer, to minimize power losses during high dV/dt transitions
Data Source
AI summary
An electronic device includes a drift region having a first conductivity type and a grid including a plurality of doped regions formed in the drift region and having a second conductivity type. The doped regions have a dopant concentration greater than 2.2×1019 cm−3. Related methods are also disclosed.