Investigations into the Impact of Deposition or Growth Techniques on the Field Oxide TID Response for 4H-SiC Space Applications

Abstract

The total ionising dose (TID) reliability of a phosphorous pentoxide (P2O5) treated SiO2 (silicon dioxide) layer is compared for the first time to other industrially relevant oxides formed on 4H-silicon carbide (SiC). Metal-oxide-semiconductor capacitors (MOSCAPs) are characterised before and after irradiation to ascertain changes in flat band voltage shift, leakage current, and dielectric breakdown (BV). Secondary ion mass spectrometry (SIMS) profiling reveals a significant phosphorus concentration near the SiO2/SiC interface, which led to improved TID resistance. The P2O5 treated oxide had the lowest leakage current at high voltage bias due to the high-temperature (1,000°C) anneal, though it had a significantly negative flat band voltage due to the high concentration of deposited phosphorus atoms. The thermal and P2O5 oxides demonstrated a TID resistance, suffering only minor shifts in flat band voltage, while the P2O5 oxide suffered the smallest decrease in its BV and the smallest leakage current rise, post-irradiation.