Mechanism of substrate charging after plasma processing

An electrostatic charge can be left on an insulating substrate after RF plasma processing, even though the plasma and surfaces are globally neutral. High voltages and breakdown can then occur when the substrate is manipulated. If the substrate is not a perfect insulator, charge appears on its back face where there is no contact with the plasma. In this case, the substrate sticks electrostatically to the electrode, and partial discharging can occur when it is lifted. Analysis of in situ charge measurements reveals the mechanism responsible for the charging, which is analogous to electrostatic chucking of the glass to the electrode when exposed to plasma.