부산대학교 도서관

This paper reports on the beneficial effects of adding silicon nitride (SiN) thin layers to protect polyimide (PI) insulation used in new, high voltage digital isolator devices. The larger bandgap of SiN enables an increased barrier height at the interfaces between metal and PI thus limiting charge injection and mitigating space charge formation in PI bulk. Wafer-level electrical tests on PI, PI-SiN, SiN-PI and SiN-PI-SiN multilayer capacitor structures are presented and show reduced leakage currents, lower HV dielectric losses and higher breakdown with SiN barriers. This is confirmed at device level with superior high voltage endurance and surge for SiN-PI-SiN insulated devices. These deliver a high working voltage of 900 V rms (750 V} rms after derating) for single die and 1500 V rms for back-to-back device with $\gt 25$ kV surge rating.