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

Abstract

The combination of TaN and TiN 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 microelectronics and thermal sensors industry. In this article, adding Ti into the TaN 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 TaN (0Ti%) and Ta-TiN 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 TaN is qusi-amorphous structure with high N 2 flow ratio of 20% while Ta-TiN 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).