PHASE FORMATION IN THIN-FILMS OF THE SYSTEM CR-SI-O

Cr-Si-O resistive films are based on a heterostructure of conductive Cr-Si phases and insulating oxide components. They are produced by .02 reactive magnetron sputtering on unheated substrates via the formation of an amorphous film which partially crystallizes during subsequent annealing. In order to determine phase formation the annealed condition was examined electron microscopically. With increasing oxygen concentration crystalline phases formed in the sequence CrSi2 (under certain conditions CrSi), Cr5Si3, Cr3Si and in accordance with the equilibrium phases of the Cr-Si binary system. A peculiarity noted was that, as well as the normal Cr5Si3 tetragonal phases, hexagonal Cr5Si3(+C) was observed and, in general, the CrSi was skipped. Elemental chromium could not be detected. Furthermore, in oxygen-free films from the silicon-rich target material silicon could also be determined. Model calculations comparing the determined phases with the corresponding film composition pointed out that the amorphous oxide residuum consisted of SiOx in which, with increasing oxygen concentration, x rose to a maximum value of 2.