Structural and electrical properties of TiNxOy thin-film resistors for 30 dB applications of pi-type attenuator

Titanium oxyhonitride (TiNxOy) thin films were deposited on SiO2/Si substrates using reactive dc magnetron sputtering and were then annealed at various temperatures in air ambient to incorporate oxygen into the films. The effect of annealing temperature on the structural and electrical properties of the films was investigated. The grain size of the films decreases with increasing annealing temperature. Crystallinity of the films is independent of annealing temperature in air ambient. Resistivity of the films increases remarkably as an annealing temperature increases and temperature coefficience of resistance (TCR) of the films varies from a positive value to a negative value. The films annealed at 350 degrees C for 30 min exhibited a near-zero TCR value of approximately -5 ppm/K. The decrease of the grain size with increasing annealing temperature was attributed to an increase of oxygen concentration incorporated into the films during annealing treatment.