Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 47 (2014)

Evaluation of single-event damages on Silicon Carbide (SiC) power MOSFETs
E. Mizuta,＊1 S. Kuboyama,＊1 T. Kambara,＊2 and T. Tamura＊1
Silicon carbide (SiC) is the material used in next
generation semiconductor devices that is applicable tohigher voltage and temperature applications because of theinherent wide energy band-gap of 3.26 eV.1) In addition,
saturated electron velocity is considerably fast in the SiC
material. Therefore, SiC devices can operate in ultra-highfrequency applications.2) If the SiC material is used inpower devices instead of Si, these devices can achieve
higher efficiency and lower loss.3) In our study, weinvestigated in detail the fatal destruction mode called
Single-Event Burnout (SEBs) on commercial SiC power
MOSFETs with the radiation effect during heavy-ion
irradiations in space.
A single ion incidence into the device generates someamount of charge according to the Linear Energy Transfer(LET) value of the ion, and the charge can be amplified in
the device using mechanisms such as avalanche
multiplication. Finally, the charge is collected at the drain
terminal and can be measured using a charge sensitive
amplifier (CSA). The input charge range and the output
voltage of CSA are 0.5 - 50 nC and 0.1 mV - 10 V,
respectively. For the cases where the amplification level
increases exponentially with the applied voltage to thesample device, the Energetic Particle Induced Charge
Spectroscopy (EPICS) is more suitable. EPICS is speciallydesigned for the pulse-height analyzer (PHA) system that isused to analyze the charge collection characteristics insemiconductor devices.4) It can measure a wide range ofcharges using a logarithmic scale. The block diagram of theEPICS system is shown in Fig. 1.
SiC power MOSFETs used in this study were commercialdevices. The maximum ratings for the drain-Source
breakdown voltage, continuous drain current, and thedrain-source on-state resistance are 1200 V, 24 A, and 220m, respectively.
The test was performed at room temperature byirradiation with a Kr-ion beam of 713 MeV using theRIKEN RILAC+RRC. Fluence was set to 1×105 ions/cm2 at
the chip surface. The drain bias voltage, VDS, was increased
at an interval of 50 V. The gate voltage, VGS, was set to 0 V
to force the devices to enter the OFF state.

Fig. 2. Collected charge spectra by Kr ion irradiation using
the EPICS system.
Figure 2 shows the EPICS spectra on SiC power
MOSFETs of Kr-ion irradiation. The cross marks Qmax
indicate the maximum collected charge for each spectrum.
There were two peaks on each spectrum similar to the oneof Si power MOSFETs.4) At the drain voltage of 100 V, thedevice was damaged because the leakage current was morethan the maximum rated zero gate voltage drain current of10 A. In Si power MOSFETs, a high energy collectedcharge peak Qmax of more than 105 pC was observed when
SEB occurs. However, in SiC power MOSFETs, permanent
increase of the leakage current was observed at the drain
voltage of 100 V; However, no high SEB peak wasobserved up to the voltage level, and the maximum
collected charge was less than 100 pC. This behavior is thesame as our previous study on SiC Schottky barrier
diodes.5) This fact suggests that the mechanism of SEB wasdifferent between SiC power MOSFETs and Si power
MOSFETs. Therefore, it is necessary to perform additional
experiments to understand the SEB mechanism of SiC
power MOSFETs.
References

1) W. E. Nelson et al.: J. Appl. Phys., 37(1), p. 333, (1996).
2) J. A. Cooper et al.: IEEE Trans. Electron Devices, 49 (4), p.658,(2002).
3) S. Yoshida et al.: Appl. Phys. Lett., 46, p. 766, (1985).
4) S. Kuboyama et al.: IEEE Trans. Nucl. Sci., 39 (6), p. 1698,(1992).
5) S. Kuboyama et al.: IEEE Trans. Nucl. Sci., 53 (6), p. 3343,(2006).

Fig. 1. Block diagram of EPICS system.
＊1＊2

Japan Aerospace Exploration Agency
RIKEN Nishina Center- 245 -