In situ compositional mapping of combinatorial materials libraries by scanning low-angle x-ray spectroscopy

A novel in situ diagnostic, scanning low-angle x-ray spectroscopy, has been introduced for compositional mapping of combinatorial thin film libraries. The technique uses high-energy electron beam-generated characteristic x rays from the films as they are deposited. The x-ray intensities are acquired dynamically, layer by layer at different film thicknesses, processed, and analyzed by Neocera-developed software using a unique algorithm. A fully automated four-axis mechanical stage facilitates data acquisition from a 2-in. diameter wafer providing a comprehensive compositional map across the wafer. A ternary materials library of Zn-Ti-Cr oxide has been deposited by continuous composition spread pulsed laser deposition to demonstrate the novel application of scanning low-angle x-ray spectroscopy for compositional mapping in situ. This in situ feedback on composition across the wafer significantly enhances the capability of any physical vapor deposition technique used for depositing combinatorial libraries, by providing compositional feedback during growth as well as the ability to monitor and control deposition processes for composition optimizations.