Oxygen Pressure Controlled Oxidation for Gate Insulator Process of SiC MOSFETs

For the improvement of a SiC/SiO₂ interface of SiC-MOSFET, we examined O₂ partial pressure (PO₂) controlled (OPC) oxidation process for the gate oxide formation. The OPC oxidation process has a potential to reduce interface state density (D_it) at SiC/SiO₂ interface by using appropriate PO₂ and oxidation temperature. However the process requires rapid thermal annealing which is not suitable for mass production. Thus we investigated the process using furnace. First, we optimized the OPC oxidation process for the furnace to realize low interface defect density. Secondly, we confirmed that reduction of D_it was determined by desorption of excess carbon in OPC process by the C–ψs measurement and X-ray photoelectron spectroscopy. Finally, a DMOSFET was fabricated using optimized OPC process. We measured the transfer characteristics, and found that the drain current with OPC was larger than without OPC process.