Comparative studies of fractal parameters of Si(100) surfaces measured by X-ray scattering and atomic force microscopy

Atomic force microscopy and x-ray scattering are applied to describe changes in the morphology of Si( 100) surfaces due to wet chemical processing. With atomic force microscopy, the rms roughness o in dependence on the lateral scan length XO is measured. Additionally, two lateral order parameters are determined, the lateral correlation length L and Hurst parameter h. With x-ray scattering, the corresponding parameters are determined. X-ray reflectometry provides the rms roughness o of the silicon surface as well as the silicon density p. X-ray diffuse or off-specular scattering gives information on the lateral order of surfaces and interfaces and allows to recalculate the fractal parameters L and h of the silicon surfaces investigated. For the results of o, L and h, atomic force microscopy and x-ray scattering give different quantities. This is attributed to the differing vertical and lateral resolution of the methods applied. Whereas x-ray scattering provides only one set of values for o, L and h, atomic force microscopy can yield different sets of values dependent on the lateral scan length X0 chosen in the atomic force microscopy measurements.