Abstract: An automatic wafer loading and pre-alignment system for integrated circuit wafer-mask Aligners. A belt feed track system is employed to transport wafers from a "send" wafer storage carrier to a wafer pre-alignment station. The wafer is machanically pre-aligned with respect to the wafer chuck of the Aligner by means of a roller arm and flat-finder system. After completion of the pre-alignment process, the Aligner turntable is rotated to carry the pre-aligned wafer and chuck to the home position of the turntable and at the same time position another chuck at the pre-alignment station. If the new chuck at the pre-alignment station contains a wafer, the wafer is transported from the chuck to a "receive" wafer storage carrier by means of a belt return track system. The feed and return wafer belt track systems have a common portion between the pre-alignment station and the respective "send" and "receive" wafer storage carriers.

Abstract: An air bearing piston assembly for semiconductor mask-to-wafer aligner which utilizes a plurality of air bearings to produce a very low friction and a very predictable force system for bringing a mask into contact and level with a semiconductor wafer. Two small driver pistons are employed to move a main piston. An outside air bearing between a rotation clamp ring and the main piston and an inside air bearing between a piston guide and the main piston produce an almost frictionless system. A third air bearing is established between a leveling ball and the ball table so that the wafer with the chunk can level accurately with a minimum of force against the mask.