Yuanzineng kexue jishu (Dec 2023)
Latent Gate Oxide Damage in SiC MOSFET Induced by Heavy Ions
Abstract
The single event effect on SiC MOSFET was studied for space applications. 1 200 V SiC MOSFET from four manufactures was irradiated with heavy ions. The ions of carbon (C), germanium (Ge), tantalum (Ta), bismuth (Bi), and uranium (U) were used. The linear energy transfer (LET) of ions was 0.26-118 MeV·cm2/mg. The static drain-source bias voltage of 50-600 V was applied on the devices under test and the electrical characteristics were measured during irradiation. The post irradiation gate stress (PIGS) test was performed. The experiment results show that single event transient current (SETC) is induced by heavy ions at 50-100 V bias voltage, single event leakage current (SELC) is induced by heavy ions at 200 V bias voltage, and single event burnout is induced by heavy ions at 200-600 V bias voltage. The experiment results confirm that the gate oxide of SiC MOSFET is the most sensitive to single event effect. Biased at about 5% of the rated breakdown voltage, the latent gate oxide damage may be induced by heavy ions. The latent gate oxide damage may further degrade to lead the gate failure during PIGS test. The latent gate oxide damage is the function of incident ion LET and bias voltage, as well as ion fluence, which is a cumulative effect. Dependent on the severity of latent gate oxide damage, the gate stress time to trigger gate failure may exceed 300 s. The mechanism of accumulate charge damage was proposed. The electric field in the gate oxide layer increases due to charges generated by the incident ions at different locations. The accumulate damage of gate oxide is caused. It is necessary to evaluate the effect of latent gate oxide damage induced by heavy ions in SiC MOSFETs for single event effect test for space application, the ion fluence used should be calculated based on the orbit and mission period, and the appropriate gate stress time should be evaluated for PIGS test.
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