X-RAY SCATTERING MEASUREMENTS OF SILICON OXIDES ON SILICON

Measurements have been made of the X-ray reflectivity and the X-ray scattering in the tails of the Bragg reflections from samples of silicon wafers with oxide layers produced by varying techniques and thicknesses. The measurements were performed by using a triple crystal spectrometer on a rotating anode X-ray source. The advantages of using a triple crystal spectrometer for these measurements are high resolution even when the surfaces are not macroscopically flat and a clear separation of the effects of the sample surface from those of the monochromator crystal. The results around the Bragg reflections provide detailed information about the end of the silicon crystal lattice - its roughness and the change in lattice parameter close to the interface. The small angle reflectivity provides information about the mean electron density including the thickness and roughness of the surface layers. The results obtained will be described and the potential of the technique reviewed