Study of polyimide films as passivation for high temperature high voltage silicon carbide devices

Characterizations of Al/Polyimide/Al capacitors in a temperature range extended up to 400 degrees C are presented. The aim is to determine the retained BPDA/PPD polyimide (PI) intrinsic dielectric and conduction properties, as a first stage in the evaluation of its ability to be applied as a passivation material for high temperature operating silicon carbide power devices. The dielectric constant, dielectric loss factor, and the static leakage current of the "as-prepared" Al/PI/Al structures are strongly affected above 175 degrees C, reaching critical values at 400 degrees C with regard to the aimed application. However, an evolution of these characteristics after the sample exposure at high temperature is observed, resulting in a very good and stabilized electrical behavior even at 400 degrees C.