Abstract: A method and apparatus for damping stepper motors are disclosed. A tachometer feedback is used to modulate the phase angle of the stepper motor command currents to achieve damping.

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.