Reactors having multiple electrodes and/or enclosed reciprocating paddles, and associated methods

A system for processing microfeature workpieces, comprising:

• a vessel configured to receive a processing fluid, the vessel having a process location positioned to receive a microfeature workpiece, the process location having a center;
• an electrode support positioned to carry at least one electrode in fluid communication with the process location;
• a workpiece support positioned to carry a microfeature workpiece at the process location of the vessel;
• a paddle device having at least one paddle elongated along a paddle axis and movable relative to the process location along a motion axis transverse to the paddle axis;
• and
• an electric field control element positioned along a flow path between the electrode support and the process location, the electric field control element being configured to control an electrical current density in the processing fluid at the process location to have a first value at a first circumferential site of the process location generally aligned with the motion axis, and a second value less than the first value at a second circumferential site of the process location generally aligned with the paddle axis, the first and second circumferential sites being approximately the same distance from the center of the process location, wherein the vessel includes vanes aligned along axes extending between the electric field control element and the process location.