The aim of the present study is to understand the mechanical properties of the Ta films having mixed phases and also having trace Nitrogen impurity.  The methodology adopted is to study the film properties: structural and mechanical, as a function of the substrate temperature.

In the present work, Tantalum films of thickness ~1μm are grown on Silicon, Quartz and 316 stainless steel substrates by using pulsed DC magnetron sputtering technique at different substrate temperatures (30^oC-420^oC).  The sputtering is carried out with pulsed (20 KHz) DC power supply (Advanced Energy Models MDX 1K, Sparc-Le20). The power density at the cathode is 2.2 w / cm². The target – substrate distance is maintained at 8 cm and the sputtering is carried out for 15 minutes. The Ta thin films have been characterized by X-ray diffraction (Xpert Panalytic) for determination of phases present in the film. The mechanical properties of the films, namely, adhesion/ peel off strength, mechanical strength (nano-indentation), and wear properties are being evaluated. The surface morphology (SEM) and the grain size (AFM) are evaluated as a function of the substrate temperature. The deposited films are studied by using GIXRD for phase analysis and crystal system identification.  Since there is considerable difference in electrical resisitivities of both the phases, the transformation of phase is also studied by electrical resistivity measurements using Vander paw method. The surface electrical properties are being evaluated non-destructively by the Kelvin probe since the chemical potential of Ta is dependent on phase and impurity of nitrogen in the films. The trace impurity compositional analysis (and the thickness) is studied by Rutherford back scattering analysis.