Reduction of interface states by hydrogen treatment at the aluminum oxide/4H-SiC Si-face interface

Processes to form aluminum oxide as a gate insulator on the 4H-SiC Si-face are investigated to eliminate the interface state density (DIT) and improve the mobility. Processes that do not involve the insertion or formation of SiO2 at the interface are preferential to eliminate traps that may be present in SiO2. Aluminum oxide was formed by atomic layer deposition with hydrogen plasma pretreatment followed by annealing in forming gas. Hydrogen treatment was effective to reduce DIT at the interface of aluminum oxide and SiC without a SiO2 interlayer. Optimization of the process conditions resulted in DIT for the metal oxide semiconductor (MOS) capacitor of 1.7×1012 cm−2eV−1 at 0.2 eV, and the peak field-effect mobility of the MOS field-effect transistor (MOSFET) was approximately 57 cm2V−1s−1.