Thermo-reliability of PVD Cr/Au on sapphire substrates for high-temperature sensors

Abstract

Thermo-reliability of physical vapor deposition (PVD) Cr/Au on sapphire substrates was systematically investigated to improve the routing interconnection for high-temperature sensors. Cr and Au films were sequentially deposited on sapphire through magnetron sputtering. Samples with various Au layer thicknesses were subjected to annealing experiments at different temperatures and times. The temperature and processing time affected the dimension of Au particles and changed the surface roughness. With the increase in the temperature and treatment time, the agglomeration of Au particles increased, and the diameter enlarged substantially. Furthermore, the agglomeration effect is enhanced with the increase in the Au film thickness. However, the annealing time under the same temperature had a limited effect on the resistance. All the samples exhibited a low resistance at 700 °C. Moreover, compared with 100/500 nm Cr/Au films, the resistance of 100/1000 nm Cr/Au films slightly changed before and after annealing at 500 °C. Thus, thermo-reliability of PVD Cr/Au was beneficial for high-temperature sensors. The results of this study provided theoretical support for the practical applications of Cr/Au films.