Characterizing Surfaces and Overlying Multilayer Structures using Grazing Incidence X-Ray Reflectivity
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at. Res. Soc. Symp. Proc. Vol. 403 0 1996 Materials Research Society
RESULTS The x-ray reflectivity characterizations and modeling results of the bare and gold coated substrates are presented in Figures 1-4. X-ray reflectivity vs grazing angle is compared for the three substrates in Figure 1. The comparison of each set of measurements and the appropriate model is shown in Figures 2-4. The characterizations and modeling results of multilayers on bare and gold coated substrates are presented in Figures 5-8. The x-ray reflectivity characteristics vs grazing angle for the three multilayers is presented in Figure 5. Comparing the three specular reflectivity curves, progressive multilayer quality deterioration from bare substrate through ion sputtered gold film to magnetron sputtered gold film is obvious. The comparison of each measured reflectivity and appropriate model is shown in Figures 6-8. For the bare substrate and the ion beam sputtered gold film, first and second order Bragg peak model and measurement amplitudes match. The graded contribution of each substrate is obvious. The bare substrate is the best foundation for a multilayer structure, followed by the ion beam sputtered gold film, and finally the magnetron sputtered film. CONCLUSIONS Well defined multilayers were produced on each of the prepared substrates. Immediate qualitative evaluation is obtained from high resolution x-ray reflectivity techniques and with simulation techniques quantitative substrate, interface, and layer details are determined. The overall quality varied with substrate preparation with the best ordered structure on the uncoated superpolished fused silica substrate and the poorest on the magnetron deposited gold film. With improved gold interlayer, the x-ray reflecting properties approach that of the best prepared bare substrate. Of the gold prepared surfaces the ion beam sputtered film is preferable. Modeling shows the multilayer on the uncoated substrate has a reflectivity curve that matches theory with the introduction of small substrate and interface roughness whereas the reflectivity curves with the added gold films require significantly larger roughness for modeled reflectivities to approach reflectivities. It follows from this work that not only can grazing incidence x-ray diffraction characterize simple film constructions, but also can extract detailed information from constructions placed on complex substrate preparations. REFERENCES 1. K. D. Joensen, P. Gorenstein, 0. Citterio, P. Hoghoj, I. Anderson, 0. Schaerpf, "Hard X-ray Wolter-I telescope using broad-band multilayer coatings on replica substrates: Problems and Solutions," in Multilayer and Grazing Incidence X-ray/EUV Optics, R. B. Hoover and A. B. C. Walker, Editors, Proc. SPIE 2515, 146-161 (1995). 2. J. Pedulla, A. Bartos, and R. D. Desslattes, in Physics of X-ray Multilayer Structures 1994, Opt. Soc. Am., Technical Digest Series, 6, 31-34 (1994). 3. B. K.Tanner, S. J. Miles, D. K. Bowen, L. Hart, and N. Loxley, "X-ray reflectometry from semiconductor surfaces and inte
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