Thin Films and Deposition Processes Studied by Soft X-Ray Spectroscopy

Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

Sammanfattning: This thesis deals with studies of thin films using soft x-ray emission spectroscopy. Thin films are frequently used in optical, semiconductor and magnetic applications, and along with the development of thin film deposition techniques, there is a growing need for thin film characterisation and production control. Soft x-ray spectroscopy provides elemental as well as chemical bonding information and has the advantage of being relatively insensitive to electric and magnetic fields. It may thus be used in-situ during deposition for monitoring sputtering deposition.Thin films of TiVN were reactively co-sputtered using two targets, and soft x-ray spectroscopy and optical emission spectroscopy were used to determine the film composition in-situ. These measurements were compared with ex-situ elemental analysis as well as with computer simulations. The results agree qualitatively and indicate that soft x-ray spectroscopy can be used for in-situ determination of film composition. In another study, the composition of chromium nitride was studied in-situ under varying deposition conditions. The fraction of different stoichiometric phases in the deposited films as a function of nitrogen flow was determined in-situ.The thesis also deals with the angular dependence of soft x-ray emission spectroscopy. The angular dependence of the emission was measured and compared to simulations for layered samples consisting of different transition metals, one sample consisting of Fe(50Å)/Cu(100Å)/V(100Å)/Si and another set of samples consisting of Fe(XÅ)/V(100Å)/MgO, where X = 25, 50 and 100 Å. The measured angular variation can be described qualitatively by calculations including refractive effects. For measurements below the critical angle of reflection, only the top layer corresponding to the evanescent wave region of 20-50 Å is probed, whereas for larger grazing angles the probe depth reaches thousands of Å. This demonstrates the feasibility of using the angular dependence as a way of studying composition and layer thickness of thin films.