Thin-Film Density Determination of Tantalum, Tantalum Oxides, and Xerogels by Multiple Radiation Energy Dispersive X-Ray Reflectivity

摘要

X-ray reflectivity provides a nondestructive technique for measuring density in thin films. A conventional laboratory, Bragg-Brentano geometry diffractometer was employed to show the generalized feasibility of this technique. X-ray tubes with chromium, copper, and molybdenum targets were used to provide a large overlap of energies for density fitting. X-ray tube alignment and sample alignment were explored to find a self-consistent measurement technique. The real and complex indices for tantalum, TaOx, and porous SiO2, also known as 'xerogel', were calculated and used in a reflectivity-fitting routine. The density results from multiple energies provided a self-checking method for true density extrapolation from misaligned samples. Density results for the xerogel films were compared with measurements by Rutherford backscattering spectrometry and by optical ellipsometry, and showed consistency within errors.