Buffer storage apparatus for semiconductor wafer processing

In a semiconductor wafer processing system having a plurality of processing stations spaced along a conveyor structure and in which the various processing stations may process wafers at different rates and in which each said processing station provides signals indicating its availability or unavailability for processing a wafer, buffer storage apparatus cooperating with three such processing stations, said buffer storage apparatus comprising

• a first buffer storage station positioned along said conveyor structure between a first and a second said processing stations and a second buffer storage station positioned along said conveyor structure between said second processing station and a third processing station,
• said first buffer storage station comprising
• first means for receiving and temporarily holding a first wafer group comprising a predetermined number of said wafers received from said first processing station and then supplying wafers from said first wafer group to said second processing station and thence to said second buffer storage station, and
• means for conveying a wafer received at said first buffer storage station to said first holding means and from said first holding means toward said second processing station;
• and
• said second buffer station comprising
• means for conveying a wafer received from said second processing station through said second buffer station to said third processing station if said third processing station is available for receiving said wafer, and
• means for receiving and temporarily holding said wafer received from said second processing station if said third processing station is unavailable for receiving said wafer and then subsequently supplying said held wafer to said third processing station when said third processing station is available;
• each said wafer receiving and temporary holding means comprising a container having means defining a plurality of fixed wafer storage positions therewithin with each said storage position being selectively alignable with the adjacent said conveying means and providing selectively for reception and holding of a wafer therewithin without interruption or release and discharge of a wafer therefrom or passage therethrough without interruption with the direction of movement of said wafer for said reception, said discharge and said passage being the same, and
• means for supporting said container and for selectively aligning a desired said container fixed storage position with said conveying means.

In a semiconductor wafer processing system having a plurality of processing stations spaced along a conveyor structure and in which a subsequent processing station may process wafers at a rate different from that of a preceding processing station and in which each said processing station provides signals indicating its availability or unavailability for processing a wafer, buffer storage apparatus positioned along said conveyor structure between the preceding station and the subsequent station, comprising

• first means for receiving and temporarily holding a first group of wafers comprising a predetermined number of said wafers received from said preceding station and then supplying wafers from said first group to said subsequent processing station when said subsequent processing station is available for receiving wafers;
• second means for receiving and temporarily holding any additional said wafers received from said preceding processing station during the time that said first receiving and holding means is holding or supplying wafers from said first group, said second receiving and holding means continuing to receive and hold said wafers from said preceding processing station until it has received and held a second group of wafers comprising a predetermined number of said wafers and then, after said first receiving and holding means has exhausted said first group of wafers in supplying wafers to said subsequent processing station, supplying wafers from said second group to said subsequent processing station when said subsequent processing station is available for receiving wafers.

In a semiconductor wafer processing system having a plurality of processing stations spaced along a conveyor structure in which a subsequent processing station may process wafers at a rate different from that of a preceding processing station and in which each said processing station provides signals indicating its availability or unavailability for processing a wafer, a buffer storage station positioned along said conveyor structure between said preceding processing station and said subsequent processing station, comprising

• means for conveying a wafer received by said storage station linearly therethrough to said subsequent processing station in response to a subsequent station availability signal;
• means selectively operable in response to a subsequent station unavailability signal to stop said linear movement of a wafer passing through said storage station on said conveying means;
• and
• means for temporarily holding said stopped wafer received from said conveying means in response to said subsequent station unavailability signal and for feeding a previously held said wafer onto said conveying means in response to said subsequent station availability signal when no wafer is available on said storage apparatus conveying means and there is at least one said wafer being held in said wafer holding means, whereby a smooth flow of wafers may be provided from a preceding station and into a subsequent station despite differences in their respective rates of wafer processing, said wafer holding means comprising
• a container having means defining a plurality of fixed wafer storage positions therewithin with each said storage position being selectively alignable with said conveying means and providing selectively for either passage of a wafer therethrough in a single direction without interruption or reception and holding a wafer therewithin or release and discharge of a wafer therefrom, and
• means for supporting said container and for selectively aligning a desired said container fixed storage position with said conveying means such that an empty said storage position is aligned with said conveying means for passing through said wafer from said preceding station or for receiving a held said wafer.