When a particle collides with a surface, depending on the particle energy and angle , it may:
bounce off (ion leaves the surface without damaging the surface)
be adsorbed physically at surface, for energies < 10 eV and it may react chemically afterwards
be implanted deep in substrate, for energies > 10 eV (first animation)
dislodge atoms - which represents the phenomena of sputtering for very high energy >> 10 eV (second animation)
Energy is partially transferred from the incoming particle to the atoms in the layer
If the energy is higher than the threshold energy (10 - 40 eV) to break bonds, then the atoms are removed
Ussualy one atom removes another atom (binary collisions), but more atoms can be involved in the process (ion A hits atom B, which hits atom C that leaves the network - see the second animation)
The processes have been compared to hitting balls in a pool game
For higher incident angles than 45, less atoms are involved and the yield is higher
Substrate preparation
