Dependence of Ar+ and Ti+ Ion Energy Distribution on Cathode Current in Magnetron Sputtering Enhanced by Additional Plasma

Energy distribution of Ar+ and Ti+ ions incident to the substrate surface in dc magnetron sputtering with an inductively coupled rf plasma excitation have been measured by an energy-resolved mass spectrometer. In addition, dc self bias of the inductive coil, cathode potential, and plasma parameters have been examined in order to discuss the correlation between these parameters and the energy distribution. In this experiment, the cathode current was variation from 0.1 A to 0.5 A for a constant coil rf power of 200 W at an Ar partial pressure of 0.3 Pa. With increasing the cathode current, the width of the energy distributions of Ar+ and Ti+ ions incident to the substrate surface became narrower and the peak energies of the energy distributions shifted to low energy. It was found that the change in peak energies of 43 to 18 eV with increasing cathode current was in good agreement with the change in the plasma potential of about 46 to 18 V.