Abstract: Apparatus for treating semiconductor wafers including a reciprocating wafer tray placed between a wafer loading station and a wafer unloading station. A station for applying photoresist and a station for heating the wafer in a vacuum chamber are placed between the loading station and the unloading station and in operative relationship to the reciprocating tray. The tray has at least three wafer carrying apertures and a pair of operating apertures located between the wafer carrying apertures. Chucks are provided at each treatment station. The wafer tray is reciprocated to feed wafers sequentially from the loading station, to the applying station, to the heating station, and then to the unloading station.