Optical emission spectroscopy and Langmuir probe characterisation of the sputtering plasma and its influence upon YBCO thin film properties

YBa2Cu3O7-x (YBCO) thin films have become the most commonly used material in HTS-based electronics applications. In order to achieve reliable performance of devices, the deposition technology must yield reproducible high-quality film growth. During high-pressure d,c. on-axis sputtering the condensing species are thermalized, whilst the biased target is under continuous bombardment. Previous investigations have shown that the state of the target (its temperature and level of oxidation) influence the composition of the plasma and hence of the film. We have used the non-intrusive plasma characterisation method of optical emission spectroscopy, as well as Langmuir probes, for a systematic study of the plasma at different deposition conditions. including small gas additions to the main gas mixture. YBCO films were characterised by X-ray diffraction and Rutherford baskscattering, (C) 2002 Elsevier Science B.V. All rights reserved.