Fabrication and Characteristics of the Reactive Sputtered Ta-N Thin Films with Ti Addition

Abstract

The combination of Ta-N and Ti-N is expected to create a range of muti-functional materials because of the composition dependent resistivity and thermal coefficient of resistance for the applications in micro-electronics and thermal sensors industry. In this article, adding Ti into the Ta-N thin film has been investigated by various sputtering conditions to create the possibility with varied electrical property which can be good for resistor and sensor application. A series of Ta-N (0Ti%) and Ta- Ti-N thin films were deposited by DC magnetron sputtering. The microstructure, composition, morphology and electrical properties of the films were characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, scanning electron microscopy and four point probe method. The crystal structures of Ta, Ti and Ta-Ti alloys are based on bcc α-Ta and bcc β-Ti. XRD patterns showed Ta-N is qusi-amorphous structure with high N 2 flow ratio of 20% while Ta-Ti-N is preferred to form polycrystalline phase. The resistivity of both kinds of thin films decreases with increasing temperatures for the nature of negative temperature coefficient of resistance (N-TCR). The magnitude of both resistivity and N-TCR increases with increasing N 2 flow ratio. The wide range of resistivity and TCR can be used for applications in thermally based micro sensors (high TCR)and thin-film resistor (low TCR).