Temperature coefficient of resistivity of TiAlN films deposited by radio frequency magnetron sputtering

Titanium aluminum nitride (TiAlN) film, as a possible substitute for the conventional tantalum nitride (TaN) or tantalum-aluminum (TaAl) heater resistor in inkjet printheads, was deposited on a Si(100) substrate at 400°C by radio frequency (RF) magnetron co-sputtering using titanium nitride (TiN) and aluminum nitride (AlN) as ceramic targets. The temperature coefficient of resistivity (TCR) and oxidation resistance, which are the most important properties of a heat resistor, were studied depending on the plasma power density applied during sputtering. With the increasing plasma power density, the crystallinity, grain size and surface roughness of the applied film increased, resulting in less grain boundaries with large grains. The Ti, Al and N binding energies obtained from X-ray photoelectron spectroscopy analysis disclosed the nitrogen deficit in the TiAlN stoichiometry that makes the films more electrically resistive. The highest oxidation resistance and the lowest TCR of -765.43 × 10^-6 K^-1 were obtained by applying the highest plasma power density.