Reliability Study of InGaP/GaAs HBT for 28V Operation

This paper reports the device process and reliability aspects of a high voltage InGaP/GaAs HBT technology for 28V operation. The key differences and challenges from the material and process perspectives relative to the conventional low voltage HBT technology are first described. Long-term reliability tests performed at 28V bias voltage, 5.2kA/cm₂ current density and 310degC junction temperature resulted in zero device failures after over 3600 hours of stress. Wafer-level reliability tests using extreme current stress conditions were used to force transistors to degrade in short time for quick checking of transistor integrity and process reliability. Transistor lifetimes were generally higher than those in conventional low voltage HBTs at similar junction temperatures. Combining with the previously reported ruggedness and linearity performance, the high voltage InGaP/GaAs HBT is a mature technology for use in the 28V high linearity power amplification