Reduction of Charge Trapping Sites in Al2O3/SiO2 Stacked Gate Dielectrics by Incorporating Nitrogen for Highly Reliable 4H-SiC MIS Devices
Superior flatband voltage (Vfb) stability of SiC-based metal-insulator-semiconductor (MIS) devices with aluminum oxynitride (AlON) gate dielectrics was demonstrated. MIS capacitors with gate insulators consisting of a thick pure aluminum oxide (Al2O3) and a thin underlying SiO2 layer fabricated on n-type 4H-SiC substrates showed a positive Vfb shift due to substrate electron injection depending on the applied gate bias and the thickness of the SiO2 interlayer. This large Vfb shift was greatly suppressed for devices with AlON/SiO2 stacked gate dielectrics, suggesting that electron trapping sites in Al2O3 film were mostly compensated for by nitrogen incorporation. This finding is helpful in realizing highly reliable SiC-based MIS field-effect-transistors (MISFETs) in terms of threshold voltage stability.
Edouard V. Monakhov, Tamás Hornos and Bengt. G. Svensson
T. Hosoi et al., "Reduction of Charge Trapping Sites in Al2O3/SiO2 Stacked Gate Dielectrics by Incorporating Nitrogen for Highly Reliable 4H-SiC MIS Devices", Materials Science Forum, Vols. 679-680, pp. 496-499, 2011