Optical emission from pulsed DC magnetron sputtering plasmas

Reactive sputter deposition of dielectric films such as Al₂O₃ in a low-pressure magnetron plasma suffers from arcing on the target electrode, which affects the quality of the deposited film and may damage the power supply. The arcing is caused by charge buildup on the dielectric film that is inevitably deposited on the target (as well as on all other inside surfaces of the vacuum chamber), even when pulsed direct current (dc) power is used. The application of a small reverse voltage pulse to the target during the "off time" (which is the period during which the main pulsed dc power is off) has been found to neutralize these charges and reduce arcing. In an effort to better understand the effects of plasma power on the microscopic details of magnetron sputtering using pulsed dc excitation, we studied the optical plasma emissions from such a plasma with a fast intensified charge coupled device camera during the sputter deposition of Al₂O₃ films.