Accelerated life testing and failure analysis of single stage MMIC amplifiers

Single stage monolithic microwave integrated circuit (MMIC) amplifiers have been high temperature accelerated life tested under DC+RF biasing conditions. Most of the circuits failed parametrically due to a gradual decrease in RF output power. Failure analysis revealed localized reduction of the gate breakdown characteristics of the metal semiconductor field effect transistor (MESFET). This was occurring through degradation of the GaAs surface Si₃N₄ passivation layer interface in the channel region of the MESFET, resulting in a reduction in the number of surface states. The few catastrophically failed MMIC´s are believed to represent a special case of this degradation process which occurred very rapidly. In contrast to the transistor, the other components of the circuits were unchanged following life test