Study On Techniques Of Soft X-Ray Grazing Fluorescence Analysis

Grazing X-ray fluorescence analysis is a new development approach of x-ray fluorescence technique in recent years. It will have good prospects and wide application in various fields, such as scientific research, quality monitoring and controlling. Especially, it becomes more and more important in the field of analysis of the thin layer's characteristics, analysis of contaminants on semiconductor wafers and surface test for ferromagnetic substance. Because grazing x-ray fluorescence techniques have the advantages, which are non-destructive nature analysis method, simple and economical for sample preparation, good fidelity and high precision for results. In this dissertation, according to the summarization of R&D and application of this kind of techniques, the theory, setup and experiment of grazing-emission x-ray fluorescence techniques are studied, which is used to characterize thin layer characteristics.In theory, firstly, the theorectical considerations on soft X-ray are discussed. Secondly, the conclusion is obtained based on the applying the Lorentz reciprocity theorem, which demonstrates that equivalence of brazing exit and grazing incidence methods. The phenomenon of interference is presented when the X-ray beam hits the thin layer sample at glancing angle, the angles corresponding maximal and minimal intensity of x-ray fluorescence are described when the phenomenon of double-beam interference or multiple-beam interference is occurred. In the theoretical description of grazing emission fluorescence, the mode of fluorescence intensity emitted from layered materials dependence of grazing angle is established by applying asymptotic approximations to double Fourier integrals, and the theoretic calculation formula of fluorescence intensity from a thin layer is derived. By the derived expressions, the theoretic simulation curves of several thin layers on Si substrate are calculated.In the experimental setup, the requirement of construction of the setup and some important parameters are brought forward. By using of an old monochomator, a set of grazing emission X-ray fluorescence spectrometer, which includes exciting source,fine sample stage, a monochromator, detecting sub-system and data processing sub-system, is designed and built with many limiting conditions exist in our laboratory. The spectrometer is the first one in our domestic area, which allows the use of gas-flow proportional counter and wavelength dispersive method. This type of configuration has the advantages of better energy resolution at longer wavelengths (soft x-ray and light elements) and a much larger dynamic range than the energy dispersive method.In experiment, the alignment and calibration to the monochromator were described firstly. Then, a gas-flow proportional counter and the Multi-Channel Analyzer (MCA) are calibrated by the radio isotope source 55Fe, and the dead time, counting rate plateau and x-ray linearity have been measured. Finally, the angular dependence of the top layer fluorescence intensity was investigated when varying the thickness of the top layer. The experimental results are good agreement with the theoretical calculations. This demonstrates the feasibility of using grazing emission x-ray fluorescence spectroscopy as a method of studying the thin layer's characteristics, such as composition and thickiness etc.With the intimately combining of theoretical, set-up and experimental research, the study on the analysis techniques of grazing emission x-ray fluorescence is developed, and the first set of grazing emission x-ray fluorescence setup is established. At the same time, the angular dependence of the fluorescence intensity with different thickness layer is measured. All the work in this thesis provides the basis for the further researches.