Evaluation of Magnetic Levitation Carrier Using Superconducting Magnetic Suspension with Superconducting Coils and Bulks

Abstract

Currently, vacuum robot hands are used to transport semiconductor wafers in vacuum equipment, and vibration suppression methods using feedback control are utilized. Using superconducting （SC） levitation allows non-contact transfer, which reduces disturbances to the wafer, and is expected to reduce vibrations caused by starting, stopping, and loading the wafer. However, a single cylindrical superconducting bulk is insufficient for the damping and stiffness of a floating body and it is thought that it is necessary to further suppress vibrations for the nanomanufacturing process. Therefore, this research proposes a new magnetic support structure that uses a permanent magnet, four superconducting bulks, and four superconducting coils to transport wafers, and to clarify the damping and stiffness in the horizontal and vertical directions through actual measurements. Finally, compared with the case without coils, the damping coefficient was 3.4 times higher, and the spring coefficient was 2.2 times higher.