[18p-Z05-1~16] 15.6 Group IV Compound Semiconductors (SiC)

▼ [18p-Z05-9] Positive V_FB shift of 4H-SiC MOS capacitors induced by Al₂O₃/SiO₂ interface dipole layer formation

〇(D)Taehyeon Kil¹, Munetaka Noguchi², Hiroshi Watanabe², Koji Kita¹ (1.Dept. of Materials Engineering, The Univ. of Tokyo, 2.Advanced Technology R&D Center, Mitsubishi Electric Corporation)

Keywords:4H-SiC, Flat-band voltage, Dipole layer

Generally, threshold voltage (V_th) of SiC-MOSFET is tuned by the channel doping concentration, however, an intentional increase in the doping concentration to achieve a sufficiently large V_th can cause a significant deterioration of channel conductance. Introduction of negative fixed charges at SiO₂/4H–SiC interface may also contribute to the positive shift of V_th, but this might have some influence on its reliability. Therefore, additional novel processes are demanded for the increase of V_th while maintaining the oxide-semiconductor interface quality or channel mobility of MOSFETs. In this work, we demonstrated the formation of an additional dipole layer on top of SiO₂ for the control of flat-band voltage of SiO₂/4H-SiC MOS capacitors. We have already clarified the dipole layer formation at SiO₂/SiC interface by interface nitridation, but in this work we are going to manipulate the dipoles formed in the gate dielectric layer by using Al₂O₃/SiO₂ interface.