Reliability improvement of Al-gate power GaAs-MESFET

This paper reports on the reliability improvement of Al-gate power GaAs-MESFET (FET) formed by the photoresist liftoff process (PLP). Al electromigration (EM) tolerance improvement with a higher deposition rate and lower outgas photoresist, a gate breakdown voltage (BVgd) improvement with fine recess control for the channel layer, and the mean time to failure (MTTF) at the 1-dB gain compression point in high-temperature RF operating life tests (HTRF) are described. We observed the parameters of the median time to failure (MTF) with high-temperature forward-bias tests (HTFB), as well as BVgd, and the gate current. The contributions of these parameters to MTTF are estimated by using an RF gate current simulation.