Properties of sputtered W-Si-N thin-film resistors

W-Si-N thin-film resistors that feature high resistivity and stability at high temperatures are presented which show promise for use in thermal printing heads and high-density hybrid ICs. The W-Si-N thin film was formed using two methods: (1) a target of mixed tungsten and silicon nitride was sputtered in an argon atmosphere; (2) a tungsten-silicide target was sputtered in an atmosphere of argon-nitrogen gas. The first method showed a better temperature coefficient of resistance (TCR) and stability at high temperatures. Typical films had a resistivity of 1800 mu Omega -cm and a TCR of -250 p.p.m./ degrees C. The resistivity of the W-Si-N thin-film resistor is found to depend on sputtering conditions, and is high when the substrate temperature is high and sputtering pressure and cathode power are low. This dependence is due to the film's nitrogen concentration. The high-temperature stability of W-Si-N thin-film resistors makes them attractive for application to thermal printing heads. The thermal printing heads fabricated using these films demonstrated high energy efficiency.<
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