ИСТИНА

We present a binary Monte Carlo (MC) model of film sputtering that is suitable at bombarding energies from just above a threshold to a few hundred eV. Instead of traditional MC programs based on mean free path (MFP) equaled to an average interatomic distance in a solid and classical calculation of a scattering angle our model uses quantum-mechanical integral atom-atom elastic cross sections (ICS) for MFP calculations and differential cross section (DCS) for computation of a scattering angle. The ab initio interatomic Ar - Si, O potentials calculated on base of the multireference Hartree-Fock method were applied to obtain the DCS and ICS which were integrated into 3D model of porous dielectrics to calculate sputtering of CVD films under Ar bombardment. The developed model is realized on 3D maps of porous solid and allows to obtain both 3D images of porous films at every time step of sputtering process and sliced distribution of trapped Ar atoms and matrix components in any direction. The size of a cell edge in the model was taken as 0.335nm that is suitable to model sputtering even of CVD films with pore radii of around 1 nm. The dependences of Si and O sputter yield and Ar reflection probabilities on angle and energy of incident Ar atoms are calculated. Space-resolved 3D maps of CVD porous films after sputtering is shown for different porosities. We expect the proposed code to be useful in plasma processing technologies because of its speed and robustness for arbitrary 3D geometry.