Reliability evaluation of a GaAs IC pre-amplifier HIC.

This work evaluates the reliability of a GaAs IC chip mounted on a Hybrid Integrated Circuit (HIC). The HIC serves as a transimpedance pre-amplifier for a photodiode or APD in lightwave transmission applications. The GaAs IC chip is fabricated using etched gate, depletion mode, n-channel FETs with Ti/Pt/Au gate and interconnect metallization. A silicon resin (DOW 648) is applied to the GaAs chip for protection. The HTOB aging has been carried out at three temperatures. The failure distributions have a sigma (lognormal) of 1.1 and show an activation energy of 1.1 eV. The predicted failure rate is less than 100 FITs for an operation ambient of 65C. The THB aging (85/85/bias) showed no failures in 1E5 device hours. These results predict a failure rate of 20 FITs at 50C and 55% R.H. The contents of this memorandum are being prepared for presentation at the GaAs IC Symposium to be given in October, 1987.