4. Conclusions
In this work, two different sensors combining retarding field analyzer and a QCM were presented. A standard two grid g-QCM was used for measurement of non-reactive sputtering of Ni and Ti. A gridless design suitable for analysis of low sputtering rate materials was used for characterization of reactive sputtering of Ti in an Ar/O2 atmosphere.
Measurements with the g-QCM analyzer showed an ionized fraction of up to 50% for Ni. No influence of the on-time was observed in this case. Somewhat higher values, exceeding 60%, were measured for Ti. In this case, there was a pronounced effect of the on-time with shorter on-time leading to higher ionized fraction at the same deposition rate.
In reactive sputtering of Ti, a substantially higher ionized fraction was observed in the oxide mode as compared to the metal mode. Already at lower values of the peak power, there was a significant fraction of Ti ions in the oxide mode. Finally, a strong effect of the distance from the sputtering target on the ionization fraction was observed.