Polycapillary optic-enhanced x-ray diffraction and fluorescence for rapid materials analysis

摘要

An energy dispersive x-ray diffraction and fluorescence (EDXRD/XRF) system with no moving parts was developed to monitor in situ the initial stages of thin film growth. The EDXRD/XRF system utilized a low power 25 W microfocus x-ray source and collimating polycapillary optics manufactured by X-Ray Optical Systems (XOS). Metastable semiconductor thin film samples containing phase-separated inclusions of Sn were analyzed for simulation of early deposition stages. The time required to obtain sufficient diffraction data from these thin films was on the order of 60 seconds. Diffraction and fluorescence data were simultaneously obtained making it possible to simultaneously determine the crystal structure and composition of thin films while they are growing. This has the potential for revolutionizing how new materials are developed and commercialized, significantly cutting development and process control costs. An additional XRF system was developed that utilized a low power 20 W microfocus x-ray source and a focusing polycapillary optic. The Sn minimum detectable limit of this system (samples of interest were Ge1-xSnx) was on the order of nanograms using the Sn-Lα signal, which corresponds to picograms from a Sn-Kα signal. Such low levels are usually only possible with a rotating anode source 103 times more powerful than the low power sealed tube source used in this experiment. An 100nm thin Ge1-xSnx sample made by ion implantation was analyzed with this XRF system. In 300 s, a detectable signal was obtained, indicating the viability of this system for in situ, thin film, composition monitoring and characterization of the first several monolayers of thin film growth.