Nano-organization of thin titanium films by an electrical field during vacuum arc deposition

Ti films were deposited onto 25 x 76 mm glass substrates using vacuum are d eposition under the following conditions: are current of 170 A, residual ga s pressure of similar to 10(-2) Pa, coating duration of 10 s, and a coating rate of 3-4.5 nm/s. A voltage of U = 0-100 V d.c, was applied during depos ition between 25 x 5-mm silver paint electrodes, separated by 20 mm, on the exposed surface of the substrates. The films were examined by atomic force microscopy (AFM), X-ray photo-electron spectroscopy (XPS), and grazing inc idence X-ray reflectometry (GIXR). AFM showed that the surface of films dep osited with applied voltage consisted of rows of titanium 'hills' separated by troughs or quasi-'valleys'. The rows had tendency to be orientated appr oximately parallel to the direction of the electric field which was applied during deposition. The surface structure was more regular and finer at U = 20 V than at U = 0 and 40 V. The film resistance was 60, 38 and 50 Omega a t U= 0, 20 and 40 V, respectively. After deposition, the samples were annea led at 450 degreesC in air for 19 h. WS showed that upper layer of the anne aled samples was composed of TiO2. AFM showed that the titanium oxide layer grown during annealing on the Ti film deposited at U= 20 V was more homoge neous than the oxide layers grown on the Ti films deposited at U = 0 and 40 V. The size of the titanium oxide grains increased with U= 0.2, 0.3 and 0. 6 mum at 0, 20 and 40 V, respectively. GIXR before and after annealing indi cated that the maximum film thickness and the minimum roughness of all inte rfaces lair-titanium oxide, titanium oxide-titanium and titanium-glass subs trate) were obtained at U= 20 V. (C) 2000 Elsevier Science B.V. All rights reserved.