Underwater wafer storage and wafer picking for chemical mechanical

Abstract

A wafer storage and wafer transfer system adjunct to a multi-station chemical mechanical polishing system. Multiple wafers are brought to the system stored in a cassette. A claw member attached to an overhead arm picks up the cassette and deposits it in a water-filled tub next to the polishing system, thereby submerging the wafers in the water with a generally vertical orientation. A blade member attached to the same arm has a recess formed in its surface connected to a vacuum generator powered by positive fluid pressure to thereby selectively apply a vacuum to the recess to vacuum chuck a wafer. The blade member vacuum chucks a wafer under the water, picks it out of the water, and deposits it on a pedestal in polishing system. One of several wafer heads on a rotating carousel picks up the wafer from the pedestal and carries it to one or more of the polishing stations for polishing. After completion of polishing, the wafer head redeposits the wafer on the pedestal. The blade member vacuum chucks the wafer and moves it from the pedestal back to the same cassette or another cassette in the water-filled tub.