Six-Degree-of-Freedom Planar Positioner with Linear Magnetic Bearings/Motors

This paper presents a planar positioner with linear magnetic bearings/motors. This positioning system is the first capable of providing all the motions required for photolithography in semiconductor manufacturing with only a single moving part, namely the platen. The single moving part generates all six-degree-of-freedom (6-DOF) motions required for focusing and alignment, and large two-dimensional motions (50 x 50 mm) for positioning. Four linear permanent-magnet motors/bearings produce suspension forces to support the platen (5.58 kg) as well as driving forces. We also demonstrate that it follows a 20-mm step motion command in only 120 ms. The stage has nanometer-order position stability and the design can be readily scaled for the next generation of photolithography.