Methods and apparatus for wetting pretreatment for through resist metal plating

A pre-wetting apparatus for pre-wetting a wafer substrate, the apparatus comprising:

• (a) a degasser configured to remove one or more dissolved gasses from a pre-wetting liquid to produce a degassed pre-wetting liquid;
• and
• (b) a process chamber comprising:
• an inlet coupled to the degasser and configured to admit the degassed pre-wetting liquid;
• at least one nozzle coupled to the inlet and mounted to a moveable arm, wherein the moveable arm is configured to position the nozzle directly above the substrate when the arm is in an active position, and away from the substrate when the arm is in an inactive position, wherein the nozzle is configured to direct the pre-wetting liquid at a grazing angle of between about 5-45 degrees to the plane of the substrate, when the arm is in the active position;
• a substrate holder configured to hold the wafer substrate in a face-up orientation, and
• a vacuum inlet configured to allow formation of a vacuum in the process chamber.