Method for determining substrate position in closed chamber and apparatus for performing the method

摘要

Provided is a method and apparatus for determining the position of a substrate within a closed chamber, the substrate being moved within the chamber by a transfer system comprising at least one rotating shaft. A load conversion element is provided adjacent to the at least one rotating shaft, and the load conversion element detects a load acting on the at least one rotating shaft and converts the load into an electrical parameter. While there is no substrate on at least one rotating shaft, a first output signal corresponding to a first value of the electrical parameter is measured. Subsequently, the output signal is monitored and the presence of the substrate on the at least one rotating shaft is detected when the output signal differs from the first output signal by a predetermined amount.