28 th ICPIG, July 15-20, 2007, Prague, Czech Republi Deposition and analysis of thin films produced in atmospheric pressure glow discharge M. Šíra, V. Buršíková, D. Franta, D. Trunec 1 Department of Physical Electronics, Faculty of Science, Masaryk University Kotlárská 2, Brno 611 3, Czech Republic The atmospheric pressure glow discharge was used for the deposition of thin organosilicon polymer films. The discharge was burning in pure nitrogen used as a carrier gas with a small admixture of organosilicon compound – hexamethyldisiloxane (HMDSO) which was used as a monomer. The temperature of the substrate was elevated up to 120 °C to obtain harder thin films. The homogeneity of thin films was enhanced using movable upper electrode. Electrical measurements were used to distinguish between glow and filamentary regime. The surface atomic composition was measured by means of X-ray Photoelectron Spectroscopy (XPS). Mechanical properties of deposited films were characterised by depth sensing indentation technique. The films were transparent in visible range. 1. Introduction Dielectric barrier discharges (DBD) are widely used for industrial purposes such as modification of polymer surface properties, e.g. wetability or adhesion, owing to the possibility of the atmospheric pressure processing and the on-line treatment. Although this method is very useful, the main disadvantage of DBDs is the lack of uniformity in filamentary regime. Under certain conditions homogeneous DBD can be obtained. Such homogeneous discharge is called atmospheric pressure glow discharge (APG discharge, APGD). The uniformity of the plasma favours this discharge type also for thin film deposition techniques. Sawada et al. [1] reported the organosilicon thin films deposition in APGD in helium with the admixture of tetraethoxysilane or hexamethyl- disiloxane (C 6 H 18 Si 2 O - HMDSO) and oxygen, Gherardi et al. [2] used N 2 /SiH 4 /N 2 O APGD for SiO 2 deposition, Foest et al. [3] used APGD in helium with admixture of HMDSO for organosilicon thin film deposition. Trunec et al. [4] deposited thin films from HMDSO and hexamethyldisilazane. In the present contribution we report the study of thin film deposition in APG discharge in nitrogen with small admixture of HMDSO. This monomer is widely used for the deposition of thin films [4]. The substrate was heated up to obtain thin films of better mechanical properties. 2. Experimental 2.1. Experimental setup The experiments were carried out in a plexi-glass discharge reactor with the dimensions 220 x 330 x 150 mm 3 . The discharge burned between two plane metal electrodes, both covered with Simax glass, 1 mm thick (see figure 1). The diameter of the bottom circle electrode was 140 mm, the dimensions of the upper rectangle electrode was 65 x 40 mm 2 . The top electrode was movable in one direction in the horizontal plane by a stepping motor to achieve better homogeneity of deposited films. The speed of the movement was 7 cm.min -1 . The space between the electrodes was set to 0.75 mm. The bottom electrode was equipped with the system of Peltier modules to heat up and cool the substrate laying on the electrode. The highest achievable temperature 120 °C was limited by the construction of the Peltier modules. The temperature was measured by platinum temperature sensor placed below the substrate. The working gas with monomer was fetched through a system of holes so the gas was flowing in the plane of the electrodes from two sides. The gas mixture was pumped off in the corner of the reactor chamber. Before the start of the experiment the discharge chamber was pumped down to 1 kPa and then filled by nitrogen to the pressure of 101 kPa. A nitrogen flow of 5.5 slpm was then added and the atmospheric pressure was maintained by slight pumping. Thin films were deposited from HMDSO. The evaporated monomer was mixed into the nitrogen by means of the Bronkhorst Controlled Evaporator Mixer. The flow rate of the monomer was 1.25 g per hour, thus the concentration of the HMDSO in nitrogen was 3160 ppm. High voltage with the frequency 6.6 kHz was used for the discharge generation. The type of the discharge as concern a filamentary or a glow mode was determined from the discharge current measurements. The power