Surface cleaning and modification of Si(100) substrates by ethanol and water cluster ion beams

The interactions of ethanol and water cluster ions with Si(100) substrates were investigated. The Si substrates were sputtered by the ethanol cluster ion beams, and the sputtering yield for the cluster ion irradiation at an acceleration voltage of 9 kV was approximately 100 times larger than that for argon monomer ion irradiation at the same acceleration voltage. In addition, surface cleaning of the Si substrates, on which a small amount of metal vapors such as Cu, Al, and Au was deposited previously as contaminative particles, was performed by irradiation of the ethanol cluster ion beams. X-ray photoelectron spectroscopy measurements showed that the contaminative metal particles were removed from the Si surface at an ion dose of 1× 1015 ions cm2. Furthermore, contact angles as well as Fourier transform infrared spectra of the Si surfaces were measured, and the wettability of the surfaces changed drastically depending on the irradiation conditions of the ethanol and water cluster ions. This is ascribed to the difference in the chemical modification of the Si surfaces by the functional groups, which were produced after the impact of the ethanol and water cluster ions on the Si surfaces.