Effect of coil-dc potential on ion energy distribution measured by an energy-resolved mass spectrometer in ionized physical vapor deposition

Energy distribution of Ar+ and Ti+ ions land plasma conditions have been in vestigated for various de potentials of the rf inductive coil in ionized ph ysical vapor deposition. The sputtering cathode used in the experiment is a conventional magnetron sputtering source with a Ti target (55 mm phi) whic h is coupled with a rf coil (60 mm phi, made of Cu). The mass spectrometer used to measure ion energy distributions is an energy-resolved type plasma monitor. The coil de potential is controlled by changing the resistance of the resistor in the termination inductance-capacitance-resistance (LCR) cir cuit connecting the coil to the ground. By increasing the resistance of the LCR circuit, the peak of the Ar+ energy spectra shifts to a lower energy. In addition it is found by the probe measurements that the plasma potential decreases with increasing the termination resistance. The changes in the p eak energy in the ion energy spectra show a good agreement with the change in the plasma potential; as a result of the change in the plasma potential, the energy distribution of ions;; accelerated toward the grounded substrat e by the sheath shifts-to a lower energy in accord with a plasma potential change. In this experiment, plasma potential is strongly affected by the dc self bias of the rf inductive coil induced by a current flow from the grou nd to the coil through the termination resistance because in the apparatus used the coil was placed inside the chamber. (C) 1999 American Vacuum Socie ty [S0734-2101(99)05404-4].