Measurement and Analysis of Body Diode Stress of 3.3 kV Sic-Mosfets with Intrinsic Body Diode and Embedded SBD

Abstract:

SiC MOSFETs display reliability issues related to the quality of SiO₂/SiC interface and bulk material due to the presence of near interface traps and point and extended material defects [1]. These material related issues give rise to a degradation of device reliability and ruggedness. One of them are basal plane dislocations (BPDs) introduced in the drift-layer during the epitaxial growth process which causes a s.c. bipolar degradation. Growth and movement of BPDs fueled by recombination energy has a very significant impact on conduction loss and on-resistance degradation. For 3.3 kV voltage capability, the probability of the appearance of BPDs is greater because the drift region is about three times larger compared to 1.2 kV devices [2-3]. We present measurement results and analysis of bipolar degradation in 3.3 kV MOSFETs with conventional body diode and embedded schottky barrier diode (SBD). The measurements were performed applying 50 % and 80 % of rated current with duty cycle 80 %, under total time of 100 hrs at constant case temperature of 54 °C. The 3rd-quadrant performance of both types of MOSFETs in pre-stress conditions was characterized at 25 and 150 °C with different gate biases of -10 V, 0 V, and +17 V. To evaluate the bipolar degradation, the diode conduction characteristics were measured at 25 °C after different stressing times by diode conduction the MOSFET output characteristics were measured at 25 and 54 °C before and after stressing the intrinsic body diode and embedded SBD. No V_SD shift was observed in diode conduction characteristics. The results indicate that the MOSFETs were fabricated on appropriate material with a sufficiently low number basal plane dislocation (BPD). The on-state resistance with V_GS = +17 V was decreased by temperature due to increased JFET resistance rather than bipolar degradation. On the other hand, the on-state resistance with V_GS = +11 V was impacted by the increased temperature and V_TH instability.

• Periodical: Materials Science Forum (Volume 1091)
• Pages: 55-59
• DOI: https://doi.org/10.4028/p-nnor4r
• Online since: June 2023
• Authors: Geon Hee Lee*, Jang Kwon Lim, Sang Mo Koo, Mietek Bakowski
• Keywords: 3.3 kV, Basal Plane Dislocations (BPDs), Bipolar Degradation, Embedded Schottky Barrier Diode (SBD), Intrinsic Body Diode, SiC MOSFETs

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