SiC Semiconductor Device with P-Type Drift Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wide-bandgap semiconductor devices, particularly those using silicon carbide (SiC), face increased on-resistance due to stacking faults and parasitic current flow through the body diode, leading to inefficiencies and higher costs in preventing current flow, especially when using Schottky diodes in parallel.
Innovation Solution
The semiconductor device design includes a high concentration n-type drain region, a lower concentration drift layer, a channel region, and specific gate and source regions, along with floating electrodes, to control current flow and prevent parasitic bipolar effects, thereby reducing on-resistance and eliminating the need for large-area diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Schottky diodes are connected in parallel with switching elements to prevent current flow through the SiC body diode, then the parasitic current flow is reduced, but the forward voltage increases and larger-area diodes are required, resulting in increased cost
Solution Approach 1:
The patent changes the conductivity type parameter of the drift layer from conventional n-type to p-type. This fundamental parameter change allows the body diode to conduct holes instead of electrons, eliminating the parasitic current flow issue while maintaining low forward voltage characteristics, thus avoiding the need for larger-area Schottky diodes and reducing cost
2Device complexity
If the SiC body diode is used as the path for reverse current, then the device structure is simplified, but the on-resistance increases due to stacking faults from carrier recombination energy
Solution Approach 1:
The patent changes the conductivity type of the drift layer to p-type, which fundamentally alters the carrier recombination mechanism. This prevents the formation of stacking faults that occur in conventional n-type structures, thereby maintaining low on-resistance while keeping the device structure simple
Solution Approach 2:
The patent converts the potentially harmful effect of carrier recombination in p-type material into a beneficial outcome by showing that p-type drift layers actually prevent stacking fault formation. The hole conduction mechanism in p-type drift layers eliminates the parasitic effects associated with electron-hole recombination in n-type 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
This design effectively prevents current flow through the SiC body diode, reducing on-resistance and maintaining high breakdown voltage, while allowing for smaller diodes with higher forward voltage, thus lowering costs and improving device performance.
Implementation Method 1
a first gate electrode controlling a surface potential of a path for current that flows from the first source region in the channel region to the drift layer
Implementation Method 2
the formation of stacking faults in the crystal structure of the SiC due to the recombination energy of the majority carriers and the minority carriers
Data Source
AI summary
A semiconductor device includes a first drain region that is made primarily of SiC, a drift layer, a channel region, a first source region, a source electrode that is formed on the first source region, a second drain region that is connected to the first source region, a second source region that is formed separated from the second drain region, a first floating electrode that is connected to the second source region and to the channel region, first gate electrodes, and a second gate electrode that is connected to the first gate electrodes.