a multi - chamber system of an etching facility for manufacturing semiconductor devices occupies a minimum amount of floor space in a clean room by installing a plurality of processing chambers in multi - layers and in parallel along a transfer path situated between the processing chambers . the multi - layers number 2 to 5 , and the transfer path can be rectangular in shape and need only be slightly wider than the diameter of a wafer . the total width of the multi - chamber system is the sum of the width of one processing chamber plus the width of the transfer path .