High temperature reliability of SiC n-MOS devices up to 630 °C

SiC based field-effect devices are attractive for electronic and sensing applications above 250 degrees C. At these temperatures the reliability of the insulating dielectric in metal-oxide-semiconductor (MOS) structures becomes an important parameter in terms of long-term device performance. We report on the reliability of n-MOS SiC capacitors following thermal stress cycling in the 330 to 630 degrees C range. As the primary mode of oxide breakdown under these conditions is believed to be due to electron injection from the substrate, the gate leakage current was measured as a function of temperature. The gate dielectric was grown using dry oxidation with a post oxidation NO passivation anneal. For large area, I mm diameter, 6H-SiC capacitors we obtain current densities as low as 5nA/cm(2) at 630 degrees C. In addition, gate leakage measurements from arrays of 300 to 1000 mu m diameter devices fabricated on different 1cm(2) 6H-SiC substrates are presented. These are encouraging results for the long-term reliability of SiC field-effect sensors.