LST-detected microprecipitates and their role in the performance of GaAs integrated circuits
The laser-scanning tomography technique has been used to explore the immediate vicinity of implanted MESFET structures in SI GaAs. From high-resolution tomography images it has been observed that apart from the well known microprecipitates which decorate the dislocations there are also process-induced particles; some are related to the n+ contacts, others are located in the bulk immediately below the grooves between the gate and source (or drain). It is shown that limiting specifications (breakdown and side-gating voltages) are correlated and both are controlled by the bulk microprecipitates, whereas the threshold voltage deviation could be attributed to the process-induced defects in the internal space between the gate and source or the gate and drain.