A High Yield Manufacturable BiFET Epitaxial Profile and Process for High Volume Production

The integration of FET in the conventional GaAs HBT process (BiFET) has provided an additional degree of freedom in the design of advance bias circuits in GaAs Power Amplifier and Analog/Mixed Signal applications. This paper discusses the development of a GaAs based BiFET technology, including the epitaxial profile and process controls to achieve high fab yield and manufacturability. Epitaxial profile that integrates an HBT and a MESFET on the same GaAs substrate and Capacitance-Voltage profiling for quality control are discussed. Influence of various fabrication process steps on FET parameters and the process optimization steps are presented. Through such careful process control procedures, high DC probe yield for the BiFET designs has been demonstrated.