The x value of the most thermally stable co-sputtered TaxCu1-x alloy films are found to correlate with measured maximum temperature coefficients of resistance as a function of alloy composition. To investigate the possible application of these materials as diffusion barriers for the Au-GaAs system, vacuum annealing and infrared rapid thermal annealing are made over a wide temperature range. Resistivity changes, X-ray diffraction, Auger electron spectroscopy, and Rutherford backscattering measurements are performed to find the metallurgical stabilities of these materials at elevated temperatures.
For high x values, the reaction temperature for TaxCu1-x, in contact with GaAs lies between 500 and 700°C. For Au in contact with TaxCu1-x the TaxCu1-x/GaAs reaction occurs at about 600°C. Amorphous Ta93Cu7 exhibits uniform mixing with surrounding elements, whereas Ta80Cu20 exhibits phase separation.