OPTIMIZATION OF TIN THIN-FILM GROWTH WITH IN-SITU MONITORING - THE EFFECT OF BIAS VOLTAGE AND NITROGEN FLOW-RATE

TiNx thin films were deposited by d.c, reactive magnetron sputtering o ver a wide range of stoichiometry. The stoichiometry, structure and co mposition were monitored by in situ spectroscopic ellipsometry (SE). T he effect of the substrate bias voltage (V-b) and nitrogen flow rate ( Phi(N)) on the above film properties was studied. Due to the bias volt age, nitrogen is extracted from the film surface and, for \V-b\ > 120 V, substantial Ti resputtering takes place. By varying the nitrogen fl ow, TiyNx phases stable at low percentages of nitrogen are deposited, while the transition to f.c.c. TiNx is always observed at Phi(N) = 1.9 sccm. X-Ray diffraction was used to identify the phases. Finally, the results of the fitting and simulation of the SE measurements using th e effective medium approximation are presented to demonstrate the suit ability of SE for the in situ characterization of complex TiyNx film s tructures offering special properties.