Grazing incidence x-ray scattering for characterizing advanced nanomaterials

X-Ray Research Laboratory, Rigaku Corporation
â—‹Kazuhiko Omote Yoshiyasu Ito

Nowadays, many kinds of surface nanostructures are extensively studied for developing various functional devices, for example, optoelectronics, microelectronics, magnetics, photonics, and so on. Size, shape, and size distributions are crucial for the performance of such nanostructures, quantum effects, magnetic domain size, etc. Grazing incidence surface x-ray scattering is well suited for characterizing such surface nanostructures. It can measure nondestructively without special sample treatments. We have developed an x-ray instrument suited for measuring surface x-ray scattering and diffraction with a laboratory x-ray source. Incident x-rays are focused on the sample surface with a very shallow angle a, and scattering x-rays are detected both in the out-of-plane (normal) and in-plane (lateral) directions. Angular resolution of the scattered x-rays can be selected by exchanging slit collimation or crystal analyzers. Therefore, we can measure surface structures in the range from nanometer to micrometer. The analysis of the observed data is carried out based on distorted wave Born approximation for taking account of refraction and reflection of x-rays on the surface and interfaces. We will present the results of analysis for several interesting materials, porous low-k dielectric films, magnetic Ni nanoparticles, and some other examples. We have determined the pore size and its distribution in porous low-k film and found anisotropy betwen the lateral and normal direction by grazing incidence small angle x-ray scattering (GISAXS). Ni nanoparticles in carbon matrix are also characterized by GISAXS and x-ray diffraction (XRD). Particle size determined by GISAXS and crystallite size by XRD agree very well; it indicates every Ni nanoparticle should be a single crystal.