Method for aligning a cassette pod to an overhead hoist transport system

摘要

A method for aligning a cassette pod on the loadport of a process machine to an overhead hoist transport (OHT) system is disclosed. The method can be carried out by marking a first standard reference line on a clean room floor to which the OHT system is aligned, followed by aligning two plumb bobs at two points that are at least 5 cm apart to the first standard reference line on the floor with tips of the plumb bobs suspended over and positioned juxtaposed to the floor. A second standard reference line is then formed by interconnecting the two plumb bobs at an elevation above a top surface of the cassette pod, followed by aligning a center line of the cassette pod to the second standard reference line. The present invention novel method can therefore be executed utilizing simple mechanical equipment without the need of a sophisticated laser alignment system.