X-ray diffraction examination of structure and stability of amorphous Cu-W thin films

Detailed studies of the structure of amorphous Cu sub 50 W sub 50 and Cu sub 66 W sub 34 thin films deposited by magnetron sputtering have been performed by x-ray diffraction (XRD) at 300K, The crystallization of both samples has been investigated by means of high temperature in situ XRD measurements from 300-1273K. The structure factors S(Q), obtained for the as-prepared samples, have a form characteristic for metallic glasses, with the intense first peak and well-developed second peak shoulder. The radial distribution function exhibits the main peak at--2.62 A with a shoulder at--3.17 A for both samples; the main peak intensity to the shoulder intensity is higher for Cu sub 6 W sub 34 than for Cu sub 50 W sub 50 . Crystallization occurs at approx420K for both thin films. The first crystalline phase that appeared was pure copper. At about 670K a bcc phase similar to tungsten appeared, having broad diffraction lines positioned at Bragg angles higher than those for pure W. On further heating the amounts of Cu and W-like phases increased while at--1150K the W-like phase started to decompose and pure W appeared.