Multilayer film passivation for enhanced reliability of power semiconductor devices

Automotive requirements are becoming ever more severe in terms of device operation under high stress and in harsh working conditions. In this context, passivation layers play a fundamental role in determining electrical performance and reliability. This study focuses on the primary and secondary passivation layers applied to the state-of-the-art power devices and their influence on reliability. Power diodes assembled in standard module packages are used as test vehicles, and high-voltage temperature humidity bias tests are performed to stress the structures. A complete failure mode analysis highlights the phenomena behind the degradation of the passivation layers. Different passivation schemes are evaluated through the application of specific inorganic and organic combinations of layers. Finally, a summary of the typical degradation mechanisms and interactions is presented.