Electrical Characteristics of SiO2/4H-SiC Metal-oxide-semiconductor Capacitors with Low-temperature Atomic Layer Deposited SiO2

Abstract

4H-SiC has attracted attention for highpower and high-temperature metal-oxide-semicon-ductor field-effect transistors (MOSFETs) for industrial and automotive applications. The gate oxide in the 4H-SiC MOS system is important for switching operations. Above 1000 degrees C, thermal oxidation initiates SiO2 layer formation on SiC; this is one advantage of 4H-SiC compared with other wide band-gap materials. However, if post-deposition annealing is not applied, thermally grown SiO2 on 4H-SiC is limited by high oxide charges due to carbon clusters at the SiC/SiO2 interface and near-interface states in SiO2; this can be resolved via lowtemperature deposition. In this study, lowtemperature SiO2 deposition on a Si substrate was optimized for SiO2/4H-SiC MOS capacitor fabrication; oxide formation proceeded without the need for post-deposition annealing. The SiO2/4H-SiC MOS capacitor samples demonstrated stable capacitance-voltage (C-V) characteristics, low voltage hysteresis, and a high breakdown field. Optimization of the treatment process is expected to further decrease the effective oxide charge density.