Surface reaction between water cluster ion and silicon substrate

The surface reaction between water cluster ions and Si substrates was investigated. The incident angle dependence of the sputtering yield of Si induced by the irradiation of a water cluster ion beam was measured at the acceleration voltage of 6 kV. The mean cluster size was 6.3 × 103 molecules. The sputtering yield of Si relative to that of normal incidence had a broad peak around the incident angle of 50°. The Si surface irradiated with a water cluster ion beam at the incident angle of 0° was more strongly oxidized than that irradiated at the incident angle of 50°. The contact angle of the Si surface irradiated with a water cluster ion beam decreased when the water cluster ion beam was irradiated at 0°, but increased at larger angles. The substrate temperature dependences of the sputter depth and numbers of disordered atoms in Si substrates indicated the limited contribution of water molecules that adsorbed on the Si surfaces to the sputtering and oxidation of the Si surfaces.