On the Impact of Electron Temperature in Magnetron Sputtering Benchmarked with Energy Flux Measurements

Abstract

In this work we have investigated the effect of increasing the electron energy as a way to increase the ionization probability of the sputtered metal (Ti) by measuring the impact of three different process gases (Ne, Ar, and Kr). Using a combined Langmuir and calorimetric probe we were able to compare the electron density ne, the electron temperature Te, the total energy influx, as well as the different energy flux contributions from charge carriers, neutrals and surface processes for various discharge conditions. The results show that the electron temperature can be increased by up to a factor of 3 by using Ne instead of Ar (or Kr). Furthermore, it was also found that by using Ne the mean free path for electron impact ionization was decreased by at least 50 %, and for higher pressures even more. In addition, we show that the contributions from sputtered neutrals and film formation represent a large fraction of the total energy influx, whereas the energy flux from ions is very low due to low ne in this type of discharge. However, by investigating changes in the electron energy flux, it was possible to study the effects of using Ne. These results may provide a way to tune the degree of ionization in sputtering processes.