Reactive sputter deposition and characterization of tantalum nitride thin films

Electrical and structural properties of tantalum nitride films, deposited on GaAs substrates by a d.c. magnetron sputtering technique at different nitrogen partial pressures for use as resistors in integrated circuits, have been reported. Sheet resistivity measurements indicate that stoichiometric TaN films with stable resistivity values can be obtained if the nitrogen partial pressure is maintained between 10.5 and 20.6%. Structural properties studied using X-ray diffraction indicate the presence of pure Ta, TaN, Ta3N5 or a mixture of Ta–N phases in the films depending on the amount of nitrogen in the sputtering gas. The temperature coefficient of resistivity measured for the films deposited with the nitrogen partial pressure around 13% showed a stable value of −200 ppm K−1. Fabricated TaN thin-film resistors showed resistance values within ±10% of the designed value, suggesting the possibility of integrating these resistors with devices.