Investigation On Plasma Property In Very High Frequency Magnetron Sputtering Discharges

The magnetron discharge is an important tool for the deposition of thin films.Progress made in the magnetron sputtering system for the past several decades, particularlyin the unbalanced magnetron system, have made it widely used. For the films deposited bymagnetron sputtering, the growth of smooth and dense films, the control of thecrystallography, phase composition, microstructure, as well as mechanical and opticalproperties are of very important. These growth and properties depend on the fraction ofionized species, which are controlled by the ion energy. The recent development on theVHF magnetron sputtering shows that the VHF magnetron sputtering discharge can controlthe fraction of ionized species, thus greatly influence the properties, compositions andstructure of deposited films. However, the plasma properties on the VHF sputtering wereseldom reported.This thesis studies the plasma property of60MHz VHF magnetron sputteringdischarge, including the electron energy distribution functions (EEDFs), the ion energydistribution (IEDS), as well as the plasma density, electron temperature, ion flux andplasma potential. As a comparison, the plasma property of13.56MHz and27.12MHz RFmagnetron sputtering discharges are also studied. The results show that the60MHz VHFmagnetron sputtering discharge produces a lower plasma density while a higher ion energyand higher electron temperature plasma. To enhance the plasma density while keeping thehigher ion energy, the ICP-assisted VHF sputtering discharge is developed, and the plasmaproperty of ICP-assisted VHF magnetron sputtering discharge is also analyzed. We foundthat the ICP-assisted discharge did not affect the feature of ion energy distribution (IEDs)but changed the electron energy distribution (EEDFs). At the same time the ICP-assisted discharge tremendously improved the plasma density with proper increase of ion flux andacceptable decrease of electron temperature. So we conclude that the13.56MHzICP-assisted60MHz VHF magnetron sputtering discharge plasma has a higher plasmadensity and higher ion energy plasma. It is expected to be used in the depositions of filmswith high deposition rate and good crystal structure.