Antenna sputtering in an internal inductively coupled plasma for ionized physical vapor deposition

Ionized physical vapor deposition (IPVD) is an emerging technology for coating high aspect ratio vias and trenches for the microelectronics industry. Ionized physical vapor deposition systems typically utilize an inductive discharge generated by an internal antenna. Because the antenna is immersed in the plasma, the possibility of antenna material sputtering into the discharge is a contamination issue. In this investigation, optical emission spectroscopy is used to acquire spectra from an IPVD system to monitor the presence of antenna metal in the discharge. The observed presence of antenna material in the spectra confirms that antenna sputtering is occurring. Experimental sputter rates as determined from witness plate observations are in reasonable agreement with predictions of a simplified model of antenna sputtering, indicating that the sputtering results from large self-bias voltages on the rf antenna. (C) 1998 American Vacuum Society. [S0734-211X(98)00802-6].