Methods and apparatuses for the production of HF in an electron-beam generated plasma. A gas containing fluorine, hydrogen, and an inert gas such as argon, e.g., Ar/SF6/H2O or Ar/SF6/NH3 flows into a plasma treatment chamber to produce a low pressure gas in the chamber. An electron beam directed into the gas forms a plasma from the gas, with energy from the electron beam dissociating the F-containing molecules, which react with H-containing gas to produce HF in the plasma. Although the concentration of the gas phase HF in the plasma is a very small fraction of the total gas in the chamber, due to its highly reactive nature, the low concentration of HF produced by the method of the present invention is enough to modify the surfaces of materials, performing the same function as aqueous HF solutions to remove oxygen from an exposed material.