Physical structures of $SiO2$ ultrathin films probed by grazing incidence x-ray reflectivity Available to Purchase

The effects of contamination overlayer and density as well as surface and interface roughnesses on the x-ray reflectivity of a $SiO2$ ultrathin film are discussed from viewpoints of experiment and theory. Grazing incidence x-ray reflectivity (GIXRR) is used to accurately measure physical structures of $SiO2$ ultrathin films grown on Si substrate by effectively resolving deviations caused by a contamination overlayer (i.e., $H2O$ and carbonaceous compounds). GIXRR results indicate that only the thickness accuracy of a $SiO2$ film is largely affected by the overlayer. The thickness of a $SiO2$ film obtained from GIXRR peak extrema and theoretical fitting reveals that if a $SiO2$ film with the thickness of $2.64nm$ is considered as a single layer, the $H2O$ overlayer with a thickness of $0.55nm$ makes the thickness of the $SiO2$ film increase to $3.09nm$⁠, and the deviation is about 17% from its corrected thickness. By evaluating the GIXRR results of three repeating measurements of a nominal $4‐nm$ $SiO2$ film, its density, thickness, and surface and interface roughnesses are $2.43±0.01g∕cm3$⁠, $3.99±0.03nm$⁠, and $0.40±0.02nm$ and $0.25±0.02nm$⁠, respectively.