Patent ID: 7782591

Claim:
Apparatus for trapping particles away from a wafer transport zone in a process chamber after plasma processing of the wafer, the apparatus comprising: a first electrode mounted in the process chamber on one side of the transport zone; a second electrode mounted in the chamber spaced from the first electrode on an opposite side of the transport zone; and a power supply connected to the first electrode to establish an electrostatic field between the electrodes and across the transport zone, the field trapping particular ones of the particles at a particular one of the electrodes so that particles in the chamber are urged away from the transport zone, wherein the second electrode is configured as an electrostatic chuck to mount the wafer in the chamber for processing and tends to release positively charged particles into the transport zone of the chamber, the electrostatic chuck is configured to supply gas against the wafer to release the wafer from the electrostatic chuck to facilitate moving the wafer into the transport zone; wherein the power supply is configured to establish the field by applying a positive DC potential to the first electrode with the electrostatic chuck connected to ground, the configured power supply causing the field to apply an electrostatic forces that trap positively charged particles at the electrostatic chuck away from the wafer in the transport zone.