INVESTIGATION OF FLUORINE IN SIO2 AND ON SI SURFACE BY THE [F(P,ALPHA,GAMMA)160]-F-19-O-16 REACTION, SECONDARY-ION MASS-SPECTROMETRY, AND X-RAY PHOTOELECTRON-SPECTROSCOPY

A fluorinated thermal SiO2, grown after HF surface treatment without de-ionized water rinse, was estimated to contain ∼3×10 13 cm-2 of fluorine by the 19F(p,αγ)16O reaction. Secondary-ion mass spectrometry data indicate that the SiF distribution is peaked at the SiO2/Si interface in the fluorinated oxide. The time-dependent change of the absolute amount of fluorine on the HF-treated silicon surface as a function of storage time in air or in vacuum was also investigated by the 19F(p,αγ)1 6O reaction. The initial number of fluorine atoms on the HF-treated silicon surface was estimated to be ∼1015 cm -2 before substantial desorption took place. Fluorine atoms desorb from the silicon surface much more rapidly if the sample is stored in air than in vacuum. These results were also supported by the x-ray photoelectron spectroscopy measurement.