ENERGY-SELECTIVE REACTION OF THE HYDROGEN-PASSIVATED SI SURFACE WITH CARBON TETRAFLUORIDE VIA DISSOCIATIVE ELECTRON-ATTACHMENT

We report the partial fluorination of a H-passivated, sputtered Si(111 ) surface at 35 K induced by irradiating a physisorbed carbon tetraflu oride overlayer with 2-13 eV electrons. The reaction cross section dep ends strongly on the energy of incoming electrons with a threshold at 4.0 eV and a clear resonance peak at 6.0 eV having a maximum value of 4.8 X 10(-17) cm(2), which is attributed to dissociative electron atta chment (DEA) to CF4. Our study demonstrates the energetic selectivity of DEA for chemically modifying a semiconductor surface.