Adsorbed water on a silicon wafer surface exposed to atmosphere

Adsorbed water on a silicon wafer surface exposed to atmosphere was investigated mainly by attenuated total reflection using Fourier-transform infrared spectroscopy. The atomically smooth hydrogen-terminated silicon wafer surface was shown to have no adsorbed water in room air. The water adsorbed on the chemically oxidized silicon wafer surface was shown to be covered by three adsorbed water-molecular layers comprising two molecular layers of liquid-phase water and one molecular layer which was directly hydrogen-bonded to the oxide surface under medium room-humidity condition. The former component reversibly adsorbs and desorbs depending on the atmospheric humidity at room temperature and the latter component desorbs in the temperature range between 100 degreesC and 300 degreesC.