A processing device including: a chamber to accommodate at least one carrier in a processing region of the chamber, an inlet structure disposed over the chamber, the inlet structure providing a merging region fluidly connected to the processing region, a first liquid control arrangement coupled at least to the chamber, the first liquid control arrangement configured to provide a first liquid in the processing region of the chamber and to raise a level of the first liquid into the merging region of the inlet structure, and a second liquid control arrangement coupled to the inlet structure, the second liquid control arrangement configured to introduce a second liquid in the merging region, wherein the first liquid control arrangement is further configured to drain the first liquid from the chamber to form a continuous surface layer of the second liquid on the first liquid and to expose the at least one carrier.