Properties of multilayered thin films for thermal ink-jet printing devices

The material properties of sputtered HfB2, Al alloy, and Ta thin films have been studied to understand their behavior in the thin film heater stack used in ink-jet printing devices. The electrical resistivity of the HfB2 heater film was found to increase with increasing working pressure, reflecting the dominant effect of grain boundary scattering on the conduction electrons. Also the stress variations in the HfB2 and Ta samples are described during the thermal cycling, respectively. The HfB2 (∼ 0.1 μm) stress can be repeatedly controlled from tension (+3 × 109 dyn/cm2, 100°C) to compression (−3.5 × 109 dyn/cm2, 400°C). However, the compressive stress of the sputtered Ta film (∼0.6 μm) was observed to increase after each thermal cycle until film cracking. Auger examinations indicate that the stress-temperature behavior of Ta is due to the incorporation of oxygen impurities resulting from the poor atmosphere seal of the quartz annealing chamber.