Hydrogen-terminated Si(lll) surfaces were patterned on the nanometer scale by field-induced oxidation with a conducting-probe scanning force microscope. The same scanning farce microscope tip was then used to measure the resulting sample topography and its local tribomechanical properties, The formation of oxide patterns with homogeneous height up to several nanometers is accompanied by a relative increase of the friction force of up to similar to 30% over the oxide layers which scales linearly with oxide height. Force modulation microscopy in the resonance mode provides a material contrast between the oxide layer and the surrounding substrate.