LOW-ENERGY (-100 EV) ION IRRADIATION DURING GROWTH OF TIN DEPOSITED BY REACTIVE MAGNETRON SPUTTERING - EFFECTS OF ION FLUX ON FILM MICROSTRUCTURE

Cross-sectional transmission electron microscopy (XTEM) has been used to investigate the effects of variations in the low-energy ion irradiation flux during the growth of reactively sputter-deposited TiN. The films were deposited on steel substrates with a negative bias of 100 V at 350-degrees-C in mixed Ar-N2 discharges at a pressure of 5 Pa (37 mTorr). The ion-to-Ti arrival rate ratio J(ion)/J(Ti) at the substrate was varied between 0.3 and 7.1 through the use of a variable external magnetic field. Films grown with J(ion)/J(Ti) less-than-or-similar-to 2 had a columnar morphology with a highly underdense microstructure. Increasing J(ion)/J(Ti) greater-than-or-similar-to 4 was sufficient to cause the growth of dense films with a more equiaxed grain structure due to renucleation. Further increases in J(ion)/J(Ti) greater-than-or-similar-to 7 resulted in increased TiN grain size and local heteroepitaxy between TiN and the martensitic phase of the substrate.