Abstract: The present invention includes an apparatus having a container (30) for storing liquid and holding a semiconductor wafer (32). The apparatus also includes a transducer (36) and a sonic generator (34). The transducer is attached to the container to transfer megasonic waves generated by the sonic generator into the container. A drain (38) releases the liquid from the container. At least one outlet opening (40) is set at the bottom of the container. Liquid inlets (42) provide the liquid to the container. Nozzles (44), connected to the liquid inlets, spray the liquid on the surface of the wafer. A liquid supply element (46) provides liquid to the container. Drive means (54), connected to the outlet opening of the container, circulates the liquid. A filter (56) is connected between the drive means and the liquid supply element to filter out residue in the liquid.