Abstract: Disclosed is a multichannel drainage system for separately draining the centrifugally broadcast residue of different liquids sequentially dispensed on the top surface of a semiconductor wafer spun on a spindle at a work station. The multichannel drainage system includes a cup assembly mounted on a cup plate which is raised and lowered by elevator apparatus. The cup assembly has a lower drainage cup forming an annular channel and a first outlet communicating with the channel. An upper drainage cup, stacked atop the lower cup, forms a second annular channel communicating with a second outlet. The elevator apparatus raises or lowers the cup plate under the action of a cam. The cam has a three-stage profile, with each stage corresponding to a stationary position of the cup assembly relative the wafer. In the home position for loading and unloading the wafer, the cup assembly is below the wafer.