Reliability Report - Phase 12

This Phase 12 reliability report adds to the extensive knowledge base published in the first eleven reports. This report details how by employing a test to fail methodology, intrinsic failure mechanisms can be identified and used to develop physics-based models to accurately project the safe operating life of a product over a more general set of operating conditions. This methodology is also employed to consistently produce more robust, higher performance, and lower cost products for power conversion applications.

Alejandro Pozo, Shengke Zhang, Gordon Stecklein, Ricardo Garcia, John Glaser, Zhikai Tang and Robert Strittmatter, Efficient Power Conversion Corporation

Key Takeaways

  • A physics-based lifetime model with supporting evidence is shown to project the lifetime of an eGaN device under gate stress over all voltages and temperature ranges.
  • A first-principles mathematical model to describe the dynamic RDS(on) effect in eGaN FETs from the basic physics of hot carrier scattering into surface traps has been developed. This model is most useful for predicting lifetimes over all voltages and temperatures in more complex mission profiles.
  • EPC developed a custom system to assess eGaN reliability over long-term ultra-high dv/dt and di/dt pulse stress conditions such as might be encountered in automotive lidar systems. As of the report date, devices have passed thirteen trillion pulses (about triple a typical automotive lifetime) without failure or significant parametric drift
  • An extensive study of thermo-mechanical stress under temperature cycling and intermittent operating life (power cycling) was conducted to experimentally generate lifetime predictions and guidelines for the selection of underfill based on key material properties.
  • eGaN devices have been in volume production for more than a decade and have demonstrated very high reliability in both laboratory testing and customer applications. Field reliability data over a period of four years and 226 billion hours of operation, most of which are on vehicles or used in telecommunication base stations, demonstrate a robustness that is unmatched by silicon power devices.