Ion patterning of Si studied by kinetic Monte Carlo using ion damage from Molecular Dynamics calculations

During molecular dynamics (MD) simulation of Xe+, 500eV ion bombardment with the incidence angle 67° on Si (001), some dislocation patterns of near surface Si atoms were observed. We focused on the distribution of adatom generation points on Si (001) surface.
After 500 single ion bombardment MD simulations, the observed distribution shapes Gaussian distribution with different aspect ratio. The center of distribution is around 1.8 nm forward from the impact point. We performed 3 dimensional lattice kinetic Monte-Carlo simulations with this adatom generation distribution and surface diffusion process. In early stage, the surface was simply roughened homogeneously and after around 3 x 10¹⁵ ion/cm² dose, the surface started to form ripple structure perpendicular to the azimuthal incidence angle with wavelength ~15 nm. The ripple moves forward to the incident angle. These processes agree nicely with experimental observation. The mechanism of ripple formation related to surface atomic flows induced by ions, surface damage distribution and Mullin’s diffusion is discussed.