Relatively thick (few micrometers) film structure estimated by back-incidence neutron reflectometry

• Published in: Physica. B, Condensed matter Vol. 551; pp. 449 - 451
• Main Authors: Miyata, Noboru, Miyazaki, Tsukasa
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.12.2018; Elsevier BV
• Subjects: Back incidence; Film thickness; Incidence; Industrial applications; Micrometers; Momentum transfer; Neutron reflectometry; Neutrons; Optics; Reflection; Reflectometry; Scattering; Substrates; Thick film characterization; Thick films; Thickness measurement; Thin films; Total reflection; Neutron reflectometry; Total reflection; Thick film characterization; Back incidence
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2018.01.012

The upper limit of film thickness that can be evaluated by neutron reflectometry is considered to be approximately 300 nm. It is difficult to characterize thick films because the Kiessig fringes arising from the interferences between the surface and interface reflections are located in the relatively high-q region. This is due to the total reflection of the incident neutrons from the film surface in the low-q region; nevertheless, for thicker layers such Kiessig fringes with high orders are smeared out from the reflectivity data in the high-q region. However, because the critical momentum transfer, below which the total reflection occurs, can be substantially reduced by the introduction of neutrons from the substrate side with a large scattering length density, it becomes possible to clearly observe Kiessig fringes of low orders in the low-q region and to characterize the structure of thick layers (back-incidence neutron reflectometry). This method allows characterizing films with thicknesses of few micrometers and can be used for various industrial applications.