Systems and methods for processing microfeature workpieces are disclosed herein. In one embodiment, the system comprises a processing chamber having a workpiece processing site configured to receive a microfeature workpiece and a main inlet through which a processing fluid can flow into the processing chamber. The system further comprises a plate in the processing chamber between the main inlet and the workpiece processing site. The plate has a first side generally facing the main inlet and a second side opposite the first side. The plate further includes a plurality of passageways extending from the first side of the plate to the second side. The individual passageways include an inlet portion projecting from the first side of the plate by a separation distance.