X-ray reflection, a technique for measuring sputtering yields of thin films

We used interference of reflected soft X-rays to measure the thickness of thin films in real time during ion beam sputtering. We have applied this technique to determine the sputtering yields of molybdenum, silicon and nickel thin films for argon and krypton ions in an energy range from 150 to 1500 eV. Sputtering yields ranging from 0.3 to 6.4 substrate atoms per incoming energetic particle have been observed. Our experiments also confirmed enhanced sputtering of silicon due to intermixing with molybdenum as predicted from T-DYN calculations. From changes in the intensity of reflected radiation it is also possible to derive changes in the surface roughness and intermixing of the thin film with the substrate at the interface during sputtering.