A magnetic levitation is suitable for moving materials in such a clean environment which must be kept free from even microscopic dust motes, for example, in a super clean room in semiconductor manufacturing plants or biochemical plants, because friction can be disappeared or reduced. In addition to this, another advantage of levitation is that the manipulator can operate as a rigid body rather than using jointed parts. In this work, the magnetic levitation is applied to transport a single wafer between semiconductor fabrication process modules in clean rooms because it can eliminate particles and oil contamination that normally exist in conventional transport systems due to contact motions of mechanical component.
The transport system consists of a wafer carrier, two levitation tracks, two stabilization tracks, and propelling system. Levitation is achieved by using antagonistic forces produced between electromagnet tracks and permanent magnets. Stabilization is achieved by using a simple feedback control. The continuous propelling force is obtained by sending specific current patterns to the propulsion coils.
The dynamic model of transport system is presented and it is verified by experiment. The system performance is experimentally investigated. The magnetically levitated wafer transport system is propelled with a reasonable speed.