A new physical effect has been revealed, consisting in an increase in the coefficient of backscattered electrons on multilayer nanostructures when they are irradiated with medium-energy electrons in a scanning electron microscope. The effect occurs on structures containing a massive substrate, on which a layer of heavier material (with a large atomic number Z) is applied, followed by coating this system with a surface film of a material with a lower atomic number. At certain energies of the primary EB electrons, the subsurface film is not visible, but at high EB it looks brighter than the uncoated areas of the sample. The calculation of the signal from individual sites was carried out, the thicknesses and depths of the individual layers of the nanostructure were found. The conditions of abnormal growth of the coefficient of backscattered electrons from subsurface sections of a multilayer sample are considered.