Electrochemical fluorine source for ultrahigh vacuum dosing

Abstract

A solid state electrochemical source was built that allows fluorine dosing at pressures below 8×10−11 Torr. The cell consists of a CaF2 crystal that is clamped between two Au plates that function as the cathode and anode. An applied voltage at elevated temperature produces an ionic current due to fluorine migration to the anode where it desorbs. This cell allows submonolayer halogen exposures, and it is ideal for studies of halogen etching because it minimizes degradation of the vacuum system and avoids toxic chemicals.

Statistical insights into the reaction of fluorine atoms with silicon

“…The same experimental procedure is used to investigate chemical reaction between SiF radicals on the silicon surface. The etching rate is measured only at low initial concentration of SiF radicals because fluorine atoms due to small atomic radius penetrate into the silicon lattice 4 , 5 . The experimental measurements 6 shown that at temperature 825 K planar removal of silicon atoms occurs together with multilayer pitting, which result in the increased surface roughness.…”