Thin Film Deposition by Low Energy SiCln + Beam

The reaction between mass-separated low-energy (30 eV) SiCl n + ion beams and Si and SiO2 substrates was studied to investigate the influence of the number of Cl atoms in SiCl n species on their deposition characteristics. It has been found that the deposition yield of Si is positive (deposition) at n=1 and it becomes negative (etching) at n=3 on the Si substrate while it is nearly zero on SiO2. In the presence of O2 gas, the deposited species change to silicon oxides and the deposition of SiO2 also takes place on SiO2 with SiCl3 +. The etching of Si by SiCl3 +, however, takes place and the etching yield was found to be unaffected by O2. These results can be explained if adsorbed Cl atoms are assumed to desorb as SiCl2, leaving either Si or Cl on the substrate depending on the value of n. In the O2 ambience, the preferred bonding of Si with O leads to the deposition of SiO2, except in the case of SiCl3 + on Si where excess Cl atoms react with Si.