Non-destructive thickness characterization of Si based heterostructure by X-ray diffraction and reflectivity

摘要

High-resolution X-ray diffraction rocking curve (RC) and X-ray reflectivity (XRR) were used to characterize the Si based heterostructures grown by reduced pressure chemical vapour deposition. The investigation focused on the reliability and accuracy of thickness measurement by the different techniques. For smooth Si epilayers grown on a thin (20 nm) strained Si_(0.9)Ge_(0.1)., buffer, it is found that both XRR and RC produce reliable values that agree well with transmission electron microscope (TEM) results over a wide range. The best-fit thickness from both XRR and RC is within ±5% of the TEM measurement, with XRR producing more accurate values than RC. However, the agreement is not good for Si epilayer grown on a thick (2 μm) relaxed Si_(0.7)Ge_(0.3) virtual substrate due to the presence of rough surface. 【Keywords】High-resolution X-ray diffraction;X-ray reflectivity;Thickness;Si based heterostructure;