Mechanism of stabilizing RuO₂/Ta₂N double layer thin film resistors

RuO₂/Ta₂N double layer thin film resistors (D-TFR) may be tuned to possess a near-zero temperature coefficient of resistance (TCR) over a temperature range of 100-400°C. It has been shown by Auger electron spectroscopy (AES), electron spectroscopy for chemical analysis (ESCA), and cross-section transmission electron microscopy (XTEM) that a distinct layered structure along with an interfacial layer exists in the RuO₂/Ta₂N double layer thin film resistor. Chemically, the interfacial layer is a ruthenium tantalum nitro-oxide, although there is a composition gradient for each element as proven by the AES depth profiling. By inserting different intermediate barrier layers in between the two resistive layers, the effects of the ruthenium-rich interfacial layer was deduced to be decisive in determining the temperature coefficient of resistance tuning process. This leads to an understanding of the mechanism responsible for zero or near-zero TCR.