Migration from an AlGaAs to an InGaP emitter HBT IC process for improved reliability

A reliable high performance InGaP emitter HBT process has been developed for RF and microwave instruments. The InGaP process achieves Ft and Fmax values of 65 GHz and 75 GHz, respectively, with BVeeo=8.4 V and beta=132. The MTTF values of >5/spl times/10/sup 5/ hours at maximum operating conditions (Tj=150/spl deg/C, Jc=0.6 mA/um/sup 2/) are an order of magnitude larger than values measured on both internal and commercially available AlGaAs emitter HBT circuits. The dominant failure mode was beta drift, consistent with other published reports for other InGaP HBTs, but the Ea of 0.68 eV is much smaller than published values, which suggests that an additional high activation energy mechanism was introduced at the high temperatures used in the published reliability tests.