Physical mechanisms limiting the manufacturing uniformity of millimeter-wave power InP HEMT's

We have developed a methodology to diagnose the physical mechanisms limiting the manufacturing uniformity of millimeter-wave power InAlAs/InGaAs HEMT's on InP. A statistical analysis was carried out on dc figures of merit obtained from a large number of actual devices on an experimental wafer. correlation studies and principal component analysis of the results indicated that variations in Si delta-doping concentration introduced during molecular-beam epitaxy accounted for more than half of the manufacturing variance. Variations in the gate-source distance that is determined by the electron-beam alignment in the gate formation process were found to be the second leading source of manufacturing variance. The statistical methodology used in this work is suitable for continuous process yield diagnostics and improvement in a manufacturing environment.