A survey on X-ray scattering techniques for structural characterization of advanced thin films

Metrology requirements are driven by advancement of industrial material and its processing technology. Research in the electronics industry has focused on reducing the thickness of thin films in the device components, integrating 3D structures with ever decreasing dimensions into the device architecture, and utilizing emerging materials for novel devices such as atomically thin materials. Such research relies on highly-reliable analytical techniques which can measure structures of objects with a desired length scale and dimension. One potential candidate is X-ray scattering, since this method is nondestructive and the obtained data are traceable to the standard unit of length. This report focuses on the following X-ray scattering techniques: X-ray reflectivity (XRR) for density and thickness of thin films, X-ray crystal truncation rod scattering (CTR) for atomic structure at interfacial region, and critical dimension X-ray small angle scattering (CD-SAXS) for 3D shape of nano-structure. The principles and characteristics are reviewed, and the problems and prospects for practical applications are discussed. (author)