The effects of passivation layers on high-frequency transistor stability

Electrical characteristic stability of a high-frequency transistor with SiO2 and Si3N4 junction surface passivation is examined by accelerated life tests in various ambients. The difference of change in current gain and collector-base breakdown voltage during life tests between tests in room-temperature air or high-humidity ambients and in dry N2 (normal can-seal ambient) is not too large. An activation energy of 1 eV is estimated for the change in current gain of the SiO2 passivated transistor in room-temperature air. The transistor with SiO2-Si3N4 passivation is highly promising, with regard to long-term stability in various ambients.