Atomic fluorine anion storage emission material C12A7-F- and etching of Si and SiO2 by atomic fluorine anions

The present study provides a novel approach to produce pure and stable atomic fluorine anions (F-) in the gas phase by using the F- storage emission material of [Ca24Al28O64](4+)center dot(O2-)(0.35)(F-)(3.30) (abbreviated as C12A7-F-), synthesized by the solid-state reaction of CaF2, CaCO3, and gamma-Al2O3. The anionic species stored in the C12A7-F- material were dominated by the F- anions, about (1.9 +/- 0.3) x 10(21) cm(-3), accompanied by a small amount of O2-, O-, and O-2(-), via ion chromatography and electron paramagnetic resonance measurements, which corroborates that the anionic species emitted from the C12A7-F- surface were dominated by the F- anions (about 90%) together with a small amount of the O- anions and electrons, identified by a time-of-flight mass spectroscopy. The absolute emission current density of F- was sensitive to the surface temperature and extraction field, reaching about 16.7 +/- 0.8 mu A/cm(2) at 800 degrees C and 1200 V/cm. A pure and stable atomic fluorine anion beam was developed by using an electrochemistry implantation method. Particularly, the atomic fluorine anions were found to be useful for the etching of Si and SiO2, evaluated by the morphological alterations via a field emission scanning electron microscope, and the surface composition's changes using X-ray photoelectron spectroscopy.