SPUTTER CLEANING OF IRON SUBSTRATES AND CONTAMINATION OF TIN COATINGS STUDIED BY INSITU AUGER-ELECTRON SPECTROSCOPY MEASUREMENTS IN AN ULTRAHIGH-VACUUM PHYSICAL VAPOR-DEPOSITION APPARATUS

The design of an ultrahigh vacuum magnetron sputtering apparatus with facilities for in situ Auger electron spectroscopy (AES) measurements and plasma diagnostics is presented. It consists of three chambers. The sample can be moved under ultrahigh vacuum conditions from the sputtering chamber through a transfer chamber to the AES analysis chamber. The three chambers are pumped separately and samples can be charged and discharged through a lock chamber without interruption of the vacuum. The sputtering unit is equipped with a quadrupole mass spectrometer and an optical multi-channel analyser for plasma diagnostics. Experiments have been performed to determine optimum conditions for the d.c. sputter-cleaning process with iron. The parameters tested are plasma voltage, sputtering time and impurity content of the gas phase. At high plasma voltages, nitriding of the surface has been observed. Further studies investigate the contamination of TiN coatings as a function of oxygen and water vapour content in the plasma atmosphere during film deposition.