CROSS-SECTION MEASUREMENTS FOR ELECTRON-IMPACT DISSOCIATION OF SIF(4)INTO NEUTRAL RADICALS

Absolute cross sections for electron-impact dissociation of SiF4 from threshold to 300 eV are presented for formation of the neutral radical s SiF3, SiF2, SiF and Si. This measurement was accomplished with thres hold-ionization mass spectrometry in a dual electron-beam device. The threshold energy for dissociation into each neutral radical was measur ed for the first time: 10.8 eV for SiF3, 13.9 eV for SiF2, 20.4 eV for SiF and 24.6 eV for Si. The surface loss probability of each radical and the electron-impact nitrogen dissociation were measured to calibra te the relative dissociation cross sections of SiF4. The magnitude of the cross section at its maximum is 0.68 x 10(-20) m2 at 80 eV for SiF 3, 0.16 x 10(-20) m2 at 100 eV for SiF2, 0.019 x 10(-20) m2 at 100 eV for SiF, and 0.0086 x 10(-20) m2 at 120 eV for Si.