Structural analysis of Co-Cr alloy films by X-ray diffraction

Co-Cr alloy films (20 at.% Cr) were deposited by DC planar magnetron sputte ring under various conditions, e.g. film thickness, Ar working gas pressure , deposition rate, substrate temperature, annealing temperature and negativ e bias voltage. The structure of the films was analyzed systematically with the X-ray diffraction technique. The preferred orientation of crystallites (texture) was evaluated from the full width at half maximum of rocking cur ve of HCP (0002) crystal planes, while the (0002) and (0004) diffraction li ne profiles were interpreted by the analytic function method. The results s how that the effective crystallite size (i.e. the coherent length in the fi lm thickness direction) is normally in the range of 20-90 nm, and the micro strain is about 3-12 x 10(-4). The increasing of bias voltage obviously mak es the microstrain increase. In addition, the decreasing of the effective c rystallite size corresponds to the degradation of the preferred c-axis orie ntation for all conditions under consideration, suggesting that the existen ce of structural defects (such as voids, stacking faults, Cr segregation, a nd twinning etc.) interrupts the coherency along the film thickness directi on and induces a random orientation of crystallites as well. (C) 1999 Elsev ier Science S.A. All rights reserved.