SiC MOSFET Resistor Mitigates Stacking Faults
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Solution Overview
Problem
Silicon carbide (SiC) semiconductor devices experience performance deterioration due to the growth of stacking faults caused by minority carrier recombination during freewheeling operations, which affects device reliability.
Innovation Solution
Incorporating a resistor with higher resistance per unit area in contact with the well contact region of the semiconductor device to reduce the injection of minority carriers into the drift layer, thereby minimizing the growth of stacking faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional MOSFET structure with Schottky barrier diode is used, then the device can perform freewheeling operation, but stacking faults grow due to minority carrier recombination causing device performance deterioration
Solution Approach 1:
A dedicated resistor is introduced as an intermediary element connected between the well contact region and source electrode. This resistor acts as a mediator to control and reduce the flow of minority carriers during freewheeling operation, thereby preventing stacking fault growth while maintaining necessary device functionality
Solution Approach 2:
The invention changes the electrical parameter (resistance) by introducing a resistor with specifically controlled resistance value. This parameter change allows control over minority carrier injection into the drift layer, reducing stacking fault generation while preserving freewheeling capability
2Ease of operation
If minority carriers are injected into the drift layer during freewheeling operation, then the parasitic diode operates, but stacking faults grow due to carrier recombination
Solution Approach 1:
The invention applies local quality by creating a non-uniform electrical characteristic at a specific location (well contact region) through the added resistor. This localized resistance modification selectively controls minority carrier flow at the critical interface without affecting the overall freewheeling operation capability of the device
3Quantity of substance
If the well contact region has low resistance for good electrical contact, then current flows easily, but minority carrier injection increases causing stacking faults
Solution Approach 1:
The invention modifies the electrical parameter (resistance) at the well contact region by introducing a resistor with optimally selected resistance value. This parameter change creates a controlled barrier that reduces minority carrier injection while maintaining sufficient current flow for device operation
Solution Approach 2:
The resistor is specifically placed at the well contact region to create a localized electrical characteristic difference. This local modification selectively controls carrier flow at the critical interface where minority carriers are generated, without affecting other regions of the device
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 resistor effectively reduces the freewheeling current density and bipolar current, maintaining high unipolar current in a wide voltage range, thus preventing device performance deterioration from stacking faults.
Implementation Method 1
The resistor is in contact with the well contact region on the second surface of the semiconductor layer and has higher resistance per unit area than the source ohmic electrode. Electric resistance of the resistor reduces the amount of minority carriers injected into the drift layer through the well contact region
Data Source
AI summary
A drift layer contains first conductivity type impurities. A well region contains second conductivity type impurities. A source region is provided on the well region and contains the first conductivity type impurities. A well contact region is in contact with the well region, contains the second conductivity type impurities, and has an impurity concentration on the second surface higher than the impurity concentration on the second surface in the well region. A gate electrode is provided on a gate insulating film. A Schottky electrode is in contact with the drift layer. A source ohmic electrode is in contact with the source region. A resistor is in contact with the well contact region and has higher resistance per unit area than the source ohmic electrode.