Mass and Energy Analyses of Substrate-incident Ions in TiO ₂ Deposition by RF Magnetron Sputtering

Mass-resolved measurements of substrate-incident ion (SII) current and ion kinetic energy distributions (IEDs) were carried out for TiO₂ deposition by rf (13.56 MHz) magnetron sputtering. Substrate-incident ion current was mainly composed of Ar⁺, O₂⁺ and O⁺. Several minor ions, such as Ti⁺,TiO⁺, ArO⁺ and Ar₂⁺ were also detected. The dominant species of substrate-incident ion was O₂⁺ at a total pressure higher than 20 mTorr, while Ar⁺ was dominant one at a total pressure of 2 mTorr with which rutile TiO₂ grew on a non-heated substrate. Variations in IEDs for Ar⁺ and O₂⁺ against total gas pressure, oxygen flow rate and applied rf power were presented. The energy with peak intensity in IED and the mean ion energy increased with both decreasing pressure and increasing rf power. Strong correlation between IEDs and the growth of crystallized TiO₂ were observed. Finally we discussed the growth condition of rutile TiO₂ films based on the results including the dc self-bias voltage.