Buffer storage apparatus for semiconductor wafer processing

DETAILED DESCRIPTION It is an object of the present invention to overcome the disadvantages of the prior art by providing buffer storage apparatus which may be incorporated within a wafer processing system having a plurality of processing stations.
It is a further object of the invention to provide such apparatus in which the identity of predetermined groups of wafers may be maintained during passage through the various stations.
It is yet another object of this invention to provide such storage means which may be positioned intermediate various wafer processing stations positioned along a conveying structure.
To achieve these and other objects a buffer storage apparatus for use in a semiconductor wafer processing system having a plurality of processing stations spaced along a conveyor structure is disclosed which includes a first buffer storage station positioned between a first and a second processing station and a second buffer storage station positioned between the second processing station and a third processing station.
The first buffer storage station includes first means for receiving and temporarily holding a first wafer group comprising a predetermined number of such wafers received from the first processing station and then supplying wafers from that group to the second processing station, and means for conveying a wafer received at the first buffer storage station to the first holding means and from that first holding means toward the second processing station.
The second buffer station includes means for conveying a wafer received from the second processing station through the second buffer station to the third processing station if the third processing station is available for receiving such a wafer.
The second buffer station also includes means for temporarily holding such a wafer received from the second processing station if the third processing station is unavailable for receiving the wafer and then subsequently supplying that held wafer to the third processing station when the third processing station is available