Metrological characterization of nanometer film thickness standards for XRR and ellipsometry applications

摘要

Two types of film thickness standards have been developed, manufactured and investigated - for X-ray reflectometry (XRR), X-ray fluorescence analysis (XRR), electron probe microanalysis (EMPA) on the one hand, and ellipsometry on the other. Metrological characterisation of both specific kinds of material measures and investigation results achieved are reported. The standards for XRR, XRF, EMPA consist of quarts substrate coated with Pt resp. a C-Ni-C-layer-system with a nominal metal layers thickness of 10 nm alternatively 50 nm. An established process for manufacture of X-ray mirrors was used for coating. XRR proved to be the dominant investigation method. Apart from film thickness characteristics like film thickness variances, interdiffusion between substrate and film have been analysed. In conclusion it can be estimated that the expanded measurement uncertainty of the film thickness for XRR applications is less than 0.5 nm. The standards for calibration of ellipsometer used for film thickness determination consist of an Si-substrate and an SiO_2-film. They are provided with an additional topographic structure making a topographic film thickness determination (approximately) possible. The nominal values of film thicknesses are between 6 nm and 900 nm. Film thickness determinations were effected by XRR, Scanning Force Microscopy in combination with Transmission Electron Microscopy as well as various ellipsometrical techniques. The consistency of results found by different measurement techniques is discussed.