Stoichiometry and thickness distribution of BaCuO2 and CaCuO2 thin films by off-axis RF sputtering

We have systematically studied the stoichiometry and thickness distribution of BaCuO2 and CaCuO2 thin films deposited by off-axis RF magnetron sputter ing. We found a strong dependence of the thickness and composition on axial distance from the target. A gradual and quasi-linear dependence was observ ed at an axial distance of 70 mm from the target. There is a minimum in the variation of both thickness and composition for all cases at axial distanc es of 75-95 mm from the target. In this region, the observed thickness drop -off and compositional uniformity over a distance of 20 mm were within 30 a nd 10%, respectively. Also the variation in the lateral direction was impro ved within 10% in thickness and 15% in composition, respectively, for a lat eral move of 10 mm from the normal axis of the target. A stoichiometrically uniform region as large as 20 x 20 mm(2) was achieved in the optimum regio n. By selecting a proper region from the target, and by adjusting the targe t composition according to the stoichiometric distribution, we were able to obtain ideal film growth with a controllable deposition rate, yielding a l arge area of homogeneous thickness and composition, with the required stoic hiometry. (C) 2001 Elsevier Science B.V. All rights reserved.