SiC Power Module Switch Modules High Current Density
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Solution Overview
Problem
High-power silicon carbide (SiC) devices face challenges with forward voltage degradation due to Basal Plane Dislocations, leading to increased on-resistance and power dissipation, especially at high temperatures and high blocking voltages, limiting their application in power modules.
Innovation Solution
A power module design incorporating switch modules with transistors and diodes, featuring a drift layer with a wide bandgap semiconductor material, optimized source region and body contact configurations to achieve high current densities and reduced on-resistance, enabling efficient power handling and switching capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If bipolar operation is used to reduce drift layer resistance, then forward voltage is reduced, but forward voltage degradation occurs over time due to Basal Plane Dislocations
Solution Approach 1:
The patent extracts the problematic bipolar operation mechanism that causes forward voltage degradation due to Basal Plane Dislocations, and replaces it with unipolar device operation (Schottky diodes and MOSFETs) that avoids this degradation mechanism while maintaining low forward voltage characteristics
Solution Approach 2:
The patent changes the operational parameters from bipolar to unipolar mode, and optimizes device structure parameters (drift layer thickness, doping concentration) to achieve low forward voltage without the degradation issue inherent in bipolar operation
2Reliability
If blocking voltage is increased to 15 kV or more, then voltage blocking capability is improved, but on-resistance increases substantially due to increased drift layer thickness
Solution Approach 1:
The patent employs silicon carbide (SiC) wide bandgap semiconductor material instead of conventional silicon, which enables achieving 15 kV or more blocking voltage with substantially lower on-resistance due to SiC's superior material properties including higher critical field and wider bandgap
Solution Approach 2:
The patent optimizes drift layer parameters (thickness, doping concentration) specifically for SiC material to achieve the optimal balance between high blocking voltage and low on-resistance, overcoming the trade-off that plagues conventional silicon devices
3Reliability
If blocking voltage is increased, then voltage handling capability is improved, but power dissipation increases due to bulk mobility reduction at high temperatures
Solution Approach 1:
The patent uses silicon carbide wide bandgap material which maintains high carrier mobility at high temperatures unlike conventional silicon, thereby achieving high blocking voltage without excessive power dissipation even in high-temperature operating conditions
Data Source
AI summary
A power module is disclosed that includes a housing with an interior chamber wherein multiple switch modules are mounted within the interior chamber. The switch modules comprise multiple transistors and diodes that are interconnected to facilitate switching power to a load. In one embodiment, at least one of the switch modules supports a current density of at least 10 amperes per cm2.