Wafer-transfer robot for use in ultrahigh vacuum

A polar coordinate wafer-transfer robot has been developed that enables thin-film manufacturing to be done in an ultrahigh vacuum. This robot features a frictionless spring structure that operates in a vacuum and is magnetically driven by a motor in the atmosphere (Nikkei Mechanical 1993.5.17). The spring arms are made of sheet springs and rigid plates and were optimized by simulation using the finite element method. All moving parts in the vacuum environment have a minimum of two bearings. As a result, a repeat position precision of 0.2 mm or less was able to be achieved in the atmosphere. Also, a maximum transfer distance of 800 mm and a transfer speed of 400 mm/s were achieved at a pressure of 10(-7) Pa. After operation in a clean room at atmospheric pressure, only three particles above 0.1 mu m in size were observed. Using this wafer-transfer robot, the area needed for film manufacturing in a multichamber ultrahigh vacuum can be reduced about 30% compared with using a conventional linear-magnet-coupling wafer-transfer robot. (C) 1997 American Vacuum Society.