Papers by Author: V. Milinović

Abstract: We present a study of the micro-structural changes induced in Cr-N layers by irradiation with argon ions. The layers were deposited by reactive ion sputtering on (100) Si wafers, to a thickness of 240-280 nm, at different nitrogen partial pressures and different substrate temperatures. The samples were subsequently irradiated with 120 keV Ar+, to 1x1015 and 1x1016 ions/cm2. Structural characterization was performed with Rutherford backscattering spectroscopy, x-ray diffraction analysis and transmission electron microscopy, and we also did electrical resistivity measurements on the samples. It has been found that the layers grow in the form of a polycrystalline columnar structure, with a columnar width of a few tens of nm. The layer composition, Cr2N or CrN, strongly depends on the nitrogen partial pressure during deposition. Ion irradiation induces local micro-structural changes, formation of nano-particles and defects, though the structures retain their polycrystalline nature. The induced crystalline defects yield an increase of electrical resistivity after ion irradiation.

Abstract: In this paper we present a study of the formation of TiN thin films during the IBAD process. We have analyzed the effects of process parameters such as Ar+ ion energy, ion incident angle, Ti evaporation rates and partial pressure of N2 on preferred orientation and resistivity of TiN layers. TiN thin films were grown by evaporation of Ti in the presence of N2 and simultaneously bombarded with Ar+ ions. Base pressure in the IBAD chamber was 1⋅10-6 mbar. The partial pressure of Ar during deposition was (3.1 – 6.6)⋅10-6 mbar and partial pressure of N2 was 6.0⋅10-6 - 1.1⋅10-5 mbar. The substrates used were Si (100) wafers. TiN thin layers were deposited to a thickness of 85 – 360 nm at deposition rates of Ti from 0.05 to 0.25nm/s. Argon ion energy was varied from 1.5 to 2.0 keV and the angle of ion beam incidence from 0 to 30o. All samples were analyzed by Rutherford backscattering spectrometry (RBS). The changes in concentration profiles of titanium, nitrogen and silicon were determined with 900 keV He++ ion beam. The RBS spectra were analyzed with the demo version of WiNDF code. We have also used X-ray diffraction (XRD) for phase identification. The resistivity of samples was measured with four-point probe method. The results clearly show that TiN thin layer grows with (111) and (200) preferred orientation, depending on the IBAD deposition parameters. Consequently, the formation of TiN thin layers with wellcontrolled crystalline orientation occurs. Also, it was found that the variations in TiN film resistivity could be mainly attributed to the ion beam induced damage during the IBAD process.