Transporting device of magnetically floating type

Abstract

A transporting device of the magnetically floating type is disposed in a central area of a multi-chamber to transport a semiconductor wafer into and out of peripheral processing rooms. The transporting device is comprised of a movable slider member having a working arm disposed along an axial direction and a server disposed at an end portion of the working arm for carrying a wafer. An electromagnet magnetically floats the slider member to drive the same in the axial direction. Sensors sense the size of the gap between the electromagnet and the slider member. Based on the magnitude of the gap, a PID circuit controls an electric current supplied to the electromagnet to maintain the slider member in a horizontal attitude state. A comparator operates to detect a variation in the electric current flowing through the electromagnet in order to determine whether the server is loaded with the wafer.

Dependencies are inferred from the claim text.