Development and fabrication of RuO₂ thin film resistors

Ruthenium oxide, RuO₂, thin film resistors on SiO₂Si or ceramic alumina substrates were fabricated using reactive d.c. magnetron sputtering. The realization of both negative and positive temperature coefficient of resistance (TCR) of the resistors made it feasible to obtain zero TCR resistors. Properties of resistors with negative or positive TCR could be easily controlled by either changing the substrate temperature or oxygen pressure during sputtering. In situ annealing of the resistors at a temperature of 250°C in oxygen atmosphere proved to be an effective way to stabilize and also to tune the TCR of the resistors which were deposited at a substrate temperature of 25°C. RuO₂ thin film resistors with a TCR in the range of 0 ± 20 ppm°C^-1 were reproducibly obtained using this approach.