Effects of bombardment by high energy gas cluster ion beams

We have developed a 200 keV gas cluster implantation system with a E × B mass filter (wien filter) which selects the cluster size in the range 1–4000 atoms, and studies the effects of bombarding an Si(100) surface with Ar cluster ions. Damaged layers irradiated with Ar cluster ion beams 3000 atoms in size at 150 keV were distributed between 100 Å and 200 Å. Detailed studies of the cluster size effect were achieved using Si(100) substrates which were covered with SiO2. By changing the thickness of the SiO2 covering, we could obtain more detailed information on the depth of the irradiation damage. The damaged layers irradiated with 100 keV cluster ion beams of size 500 and 3000 atoms were about 130 Å and 160 Å respectively. However, the depth of the damaged layer was much greater than the value expected from the cluster velocity at the energy of the constituent atoms of the cluster. These results indicate that gas cluster ion irradiation has the capability of producing shallow implantation.