THEORETICAL SIMULATION OF BACKSCATTERED ELECTRON IMAGES OF SI SIXGE1-X STRUCTURES WITH A SCANNING ELECTRON-MICROSCOPE

In this work, we report on a theoretical study of the contrast formation at Si/SixGe1-x interfaces in backscattered electron images of a scanning electron microscope. The contrast at the heterointerface is calculated for different atomic concentrations (0 < x < 1) and energies (E0 = 10 and 20 keV). The electron scattering phenomenon is simulated by employing a Monte Carlo method by using a single scattering approach. The signal intensity close to the interface shows a peak on the alloy side and a dip on the Si side. We explain this phenomenon by using the diffusion theory of the backscattered electrons. The spatial resolution increases by decreasing the Si concentration in the alloy side and by decreasing the beam energy.