Diagnostics of the radio frequency magnetron discharge plasma used for TiO2 thin film sputtering deposition

The density, temperature and energy distribution function of the electrons of the plasma nearby the deposition substrate of a radio frequency magnetron discharge used for sputtering deposition of TiO2 thin films were measured by a cylindrical Langmuir probe. In the low-energy domain (0–15 eV), the electron energy distributions resembled a Maxwell distribution with a temperature value that decreased from 5 to 3 eV by the increase of the argon pressure from 1 to 20 mTorr. In the high-energy domain the electron energy distribution showed a depletion. At low values (approx. 0.5 sccm) the flow rate of argon affected the plasma density. This effect was attributed to the gas composition change induced by the atoms sputtered from the cathode titanium dioxide target, change that was proved by optical emission spectroscopy measurements.