The ADP source uses neutral Ar gas and a DC arc to strike the plasma. A chimney effect draws the reactants into the plasma, where they are directed toward a wafer. The ADP source consumes and releases power in a precisely regulated process. The power required to maintain the plasma is provided using a relatively small electrical current and a long arc. The resultant lower power density allows a reduction in the heat flux to the electrodes and, as a result, minimizes thermal erosion and plasma contamination while increasing electrode life.
Magnetic fields control both the location and power density of the plasma.
The plasma is spread over a zone of several square centimeters but the footprint is still smaller than a wafer. The minichambers are electrically isolated from the electrodes. When a DC field is applied between the two electrodes, a plasma arc is formed that exits the orifice of one electrode unit and enters the orifice of the other. The plasma is kept from the chamber walls by the flow of mainstream gas. External magnetic fields direct the plasma arc from its initial path so that a portion can be extended vertically.