Amorphous silicon (a-Si:H) thin films have been deposited on glass by radio frequency plasma enhanced chemical vapour deposition (rf-PECVD) to verify the influence of SF6 plasma on their characteristics when partially etched at room temperature in a home-made reactive ion etching (RIE) system, operating at 13.56 MHz. The plasma etching parameter studied was the rf power, P, which varied in the range 10 - 100 W. The surface chemical composition of the films has been examined by XPS. The etchings profiles have been investigated by SEM. XPS results clearly show that there is no evidence of the presence of surface sulphur (S). However, a great amount of surface fluorine (F) was detected with increasing rf power and its diffusion into the a-Si:H films also increases with rf power. SEM showed anisotropic structures that increase with rf power.