A Study of Post Annealing Effects in the Repair of High Resistance Failures with Unstable Schottky Barrier Height in 4H-SiC Schottky Barrier Diode

Abstract

To improve the high resistance and low Breakdown Voltage (BV) of 4H-SiC SBD, the metal annealing process is usually used to to stabilize SBH. We confirmed that post metal annealing after the chip process also stabilizes SBH by the post annealing experiment of applying failure chips (4H-SiC Ti/Al SBD) that have a forward current (IF) under 1 [A] with high resistance, because of the metal annealing process error. The result of experiments showed that the IFincrement and BV decrement are proportional to the applied temperatures over 450 °C, and the second additional post annealing shows a decrease of IFand BV. Aluminum and Titanium transformation with post metal annealing made a decrease of SBH, so that the on-resistance is decreased and BV is decreased (in severe cases, the intense post annealing generates Aluminum spiking). From a result of this work, using a suitable post metal annealing, we can improve the IFof SiC SBD with a high resistance failure from the metal process event.