CRYSTALLIZATION BEHAVIOUR OF Al-W AMORPHOUS THIN FILMS

N. Radia¹, A. Tonejc², A.M. Tonejc², J. Ivkov³ and T. Car¹

¹Institute Ruder Boškovia, Bijenieka 54, POBox 1016, 10001 Zagreb, Croatia
²Faculty of Science and Mathematics, Department of Physics, Bijenieka 32, POBox 162, 10001 Zagreb, Croatia
³Institute of Physics, Bijenieka 26, POBox 304, 10001 Zagreb, Croatia

Keywords: Amorphous Thin Films, XRD, Al-W, codeposition

The Al-W thin films, with composition in the range from Al₈₀W₂₀ to Al₆₆W₃₄, were prepared by simultaneous d.c. sputtering of both aluminium and pure tungsten (on glass, fused quartz, alumina or sapphire as substrates) in a multiple source sputtering apparatus. The prepared films was investigated by XRD using a Philips PW 1820 vertical goniometer with monochromatized Cu K_a radiation and by measuring electrical resistivity. Thin films were found completely amorphous and the negative temperature coefficient of the electrical resistivity confirmed the amorphous state.

Thermal stability of amorphous films deposited on fused quartz was investigated by isothermal annealing procedure. It was found that amorphous films did not crystallize up to 400⁰C. However, at 500⁰C and higher temperatures, the W₂Si phase and some unidentified lines were detected on XRD patterns on films deposited on quartz substrate, showing the reaction of films with substrate.

As-deposited films on alumina substrates were also amorphous and stable up to 500⁰C. Investigation of the crystallization behaviour of the amorphous films, using annealing procedure on temperatures between 530⁰C and 690⁰C, are now in progress. The results will be available at the time of Conference.