CHARACTERIZATION OF TIN FILMS GROWN BY REACTIVE DC TRIODE SPUTTERING ONTO COPPER SUBSTRATES

TiN films with a thickness varying from 70 to 300 nm were deposited on to Cu substrates by reactive d.c, triode sputtering. The characteristi c features of the deposition system are described in detail. In order to vary the structure of the as-deposited films, they were grown with and without substrate heating and with substrate bias. The as-deposite d films (unheated substrate) were quasi-stoichiometric, as determined by Auger electron spectroscopy (AES). Transmission electron microscopy (TEM) showed that the latter films were randomly oriented crystal wit h a grain size between 8 and 12 nm, whereas the films deposited under substrate heating (250-400 degrees C) or under substrate bias (-250 V) had larger grain size, between 50 and 600 nm, consisting of monocryst alline areas with (110) and (100) orientations parallel to the substra te plane. We determined a parameter value of 0.425 nm by electron diff raction as well as by X-ray diffraction for the as-deposited films (un heated substrate). A TEM cross-section of the latter showed a dense vo id-free columnar structure. It was shown also that this columnar struc ture is independent of the atomic fraction of the nitrogen. Finally, a nnealing of samples prepared without substrate bias at 700 degrees C f or 30 min showed from the AES depth profiles that there is no diffusio n of Cu to the outer surface of the films and also that no reaction oc curs at the interface. This behaviour is related to the low pressure a nd small deposition rate used.