Reliability study on InAlAs/InGaAs HEMTs with an InP recess-etch stopper and refractory gate metal

Preliminary BT-stress tests for 0.1 mu m-gate InAlAs/InGaAs HEMTs, with an InP recess-etch stopper and a refractory metal gate, were carried out. By employing WSiN as a gate metal, threshold voltage shift, caused by metal sinking into the InP recess-etch stopper during the fabrication process or thermal stresses after the gate formation, was eliminated. A decrease in saturation current is the major failure mode, where the activation energy in the 175-215 degrees C temperature region and the extrapolated median lifetime at 125 degrees C were estimated to be 1.6 eV and over 10(5) h, respectively. The observed failure mode is associated with an increase in drain resistance and is suggesting that the degradation mechanism is related to the applied field. (C) 1997 Elsevier Science Ltd.