Influence of the DLC Passivation Conductivity on the Performance of Silicon High-Power Diodes over an Extended Temperature Range

The diamond-like carbon (DLC) is important for passivation of junction termination in high power devices due to its excellent electrical, mechanical, and thermal properties. While the role of conductivity and polarization of the DLC layer on the blocking capability of a p-n junction has been explained recently, the thermal behavior still needs to be addressed. For this purpose, the diode leakage current was measured on large area power diodes with negative bevel coated by the DLC in a typical industrial range between 300 and 413B K. An unusual deviation from the expected Arrhenius law was experimentally observed. A predictive TCAD model, which incorporates the effect of the DLC layer, has been developed to study the impact of the DLC layer parameters on diode thermal performance. Both the electrostatic features and charge transport mechanisms through and along the DLC/Silicon interface have been modeled over a wide range of temperatures. Different DLC/Silicon doping combinations have been analyzed to explain the main effects determining the temperature dependence of diode leakage current and breakdown voltage. A complete validation of the TCAD approach has been achieved.