Role of substrate current in the reliability life testing of gaas mmics

GaAs monolithic microwave integrated circuits (MMICs) typically show a dramatic increase in circuit current when operated above 200°C. This increase in current has been found to be in good agreement with a summation of the estimated substrate current flowing from the individual components of these circuits through the bulk GaAs to the back metalization. Although the substrate current for these MMICs was small at room temperature, it can be a substantial portion of the total circuit current at the high temperatures typical for accelerated life testing. A procedure was developed to compensate for the substrate current, thus allowing normal circuit operation during high temperature life testing.