SiC MOSFET Total Dose Testing via Annealing
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Solution Overview
Problem
Conventional radiation testing methods for silicon carbide (SiC) MOSFETs are not applicable due to differences in the total ionizing dose effects and failure mechanisms compared to silicon (Si) MOSFETs, necessitating a specific test method to evaluate the anti-radiation level of SiC MOSFETs.
Innovation Solution
A method involving pre-irradiation and post-irradiation annealing processes, including high-temperature annealing under positive and negative gate biases, to determine the shift in threshold voltage and assess the anti-radiation level of SiC MOSFETs, which considers the unique characteristics and defects of SiC/SiO2 interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional radiation testing methods for Si MOSFETs are applied to SiC MOSFETs, then testing simplicity is maintained, but measurement precision and reliability of anti-radiation evaluation deteriorate due to different total ionizing dose effects and failure mechanisms
Solution Approach 1:
The testing process is segmented into distinct phases: pre-irradiation annealing, irradiation, and post-irradiation annealing. Each phase has specific measurement objectives and criteria, allowing comprehensive evaluation while maintaining systematic control over the complex testing procedure
Solution Approach 2:
Pre-irradiation annealing is performed before radiation exposure to establish baseline threshold voltage characteristics and eliminate initial trapped charges. This preliminary action ensures that subsequent measurements accurately reflect radiation effects rather than manufacturing variations or initial device states
2Measurement precision
If multiple annealing processes are performed to account for SiC/SiO2 interface characteristics, then measurement precision improves, but loss of time increases due to extended testing duration
Solution Approach 1:
The testing methodology employs periodic annealing cycles at specific time points (pre-irradiation and post-irradiation) rather than continuous monitoring. This periodic approach captures critical threshold voltage changes while minimizing total testing time compared to continuous measurement protocols
3Measurement precision
If pre-irradiation and post-irradiation annealing are performed to evaluate inherent defects, then measurement precision improves, but device complexity increases due to additional processing steps
Solution Approach 1:
Threshold voltage measurements from pre-irradiation annealing serve as feedback to establish baseline characteristics and determine appropriate irradiation dosages. Post-irradiation measurements provide feedback on radiation-induced changes, enabling accurate separation of inherent defects from radiation effects through comparative analysis
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 method effectively evaluates the anti-radiation level of SiC MOSFETs by accounting for both radiation-induced and inherent defects, providing a comprehensive assessment of their performance under total ionizing dose effects, guiding design improvements and radiation reinforcement.
Implementation Method 1
the SiO2 gate oxide layer in the SiC MOSFET is formed through oxidizing SiC. In the latter oxidization, C or CO is released
Implementation Method 2
subject to the total ionizing dose effect in which trapped charges are generated in the oxide layer due to radiation
Implementation Method 3
performing pre-irradiation annealing on a group of SiC MOSFET devices... the pre-irradiation annealing comprises high temperature annealing under a positive gate bias and high temperature annealing under a negative gate bias
Data Source
AI summary
A method for testing the total dose effect of a SiC MOSFET device, realizing verification of the complex total dose effect of the SiC MOSFET. The test steps sequentially comprise: testing a tested device before irradiation; performing annealing treatment on the tested device before irradiation; performing an irradiation test on the tested device; performing annealing treatment on the tested device after irradiation; performing test data analysis and processing on the tested device after irradiation. In the test process, threshold voltage shift caused by total dose radiation-induced defects and threshold voltage shift caused by near interface trap charges inherent near a SiC MOSFET interface are measured respectively, comprehensive analysis and calculation are carried out on the test result, the total dose effect resistance capability of the SiC MOSFET device can be given, and a certain guiding effect on device reinforcement is achieved.