1. Attempt to non-destructive SEB testing of 1.2 kV SiC MOS
Viliam Senaj, Tobias Stadlbauer
April 13th, 2017

2. Schematics of protection circuit used of GTO/IGBT

3. Collection of data by a low speed data logger

4. DUT (Rad. Room)
Measurement and Distribution Box (Control Room)
HV Power Supply (Control Room)
Data Logger (Control Room)
Control Software (Virtual Machine)
Data Viewer (Web Interface)

5. Measurement and Distribution Box

6. Non-destructive SEB testing GTO, IGBT, SiC MOS
GTO like thyristors within voltage span 2.6 kV – 3.1 kV (various types 4.5 kV rated)
IGBTs 800V – 3 kV (various types and producers with rating 1.2 kV, 1.7 kV, 4.5 kV)
Limited damage to GTO/IGBT during non-destructive testing (almost) confirmed by slots where we got up to tens of SEBs per DUT with reasonably reproducible SEBc- s: 5 DUT Dynex GTO DG648BH at 2.7 kV:
SEBc-s = 1, cm2 after first 49 SEBs
SEBc-s = 1, cm2 after 99 SEBs
SEBc-s = 0, cm2 after 162 SEBs
Nevertheless, it happened, that DUT failed in short-circuit (current is limited by protection circuit to ~100s of uA and hence not disabling measurement of other components on the same setup)
First experience with 1.2 kV SiC MOS – destructive failure after first SEB – protection circuit not fast enough…

7. Modified protection circuit for SiC MOS

8. Attempt to a no non-destructive testing of SiC MOS
No damage to 1.2 kV rated SiC at test voltage up to 1.2 kV – but no SEB detection neither: voltage on DUT was reduced before logic level on monostable multivibrator reached
Modified (slower) protection circuit used during slot in November – detection OK but one type of SiC MOS damaged after first SEB (protection not fast enough?)
Alternative protection circuit is under development

9. SiC MOS (destructive) SEB measurement results

10. SiC MOS SEB measurement without SEB observed

11. Conclusion Non-destructive SEB test of SiC MOS not not achieved yet
Non-destructive SEB testing SiC MOS more demanding than Si?
SEB cross-section of SiC is probably more dependent upon producer technology (or underevaluating max D-S voltage) and there is not a simple rule for voltage derating: similarly rated (1.2 kV) ROHM SiC MOS behaving differently compared to VOLFSPEED ones