Chemical sputtering of a-C:H films by simultaneous exposure to energetic Ar⁺ ions and water vapor

Amorphous hydrocarbon films (a-C:H) were exposed to a beam of 800eV Ar⁺ ions. The temperature of the films was varied between 110 an 800K. When backfilling the chamber with water vapor during ion bombardment there is a marked increase of the erosion rate at and below 200 K, while there is no influence on the erosion rate at room temperature and above. We explain the observed synergism by an ion-induced reaction between adsorbed water molecules and the film surface in which volatile erosion products are formed.