Multi-axis maglev nanopositioner for precision manufacturing and manipulation applications

We present a 6-axis magnetic levitation (maglev) stage capable of precision positioning down to several nanometers. This stage has a simple and compact mechanical structure advantageous to meet the performance requirements in the next-generation nano manufacturing. It uses the minimum number of linear actuators required to generate all 6-axis motions. Three vertical actuators are used to levitate the moving part, namely the platen, and maintain its vertical position. Other three horizontal actuators control its position and rotation in the horizontal plane. In this paper, we describe the electromechanical design, modeling and control, and the electronic instrumentation to control this maglev system. We modeled the platen as a pure mass due to negligible spring and damping forces while it is levitated without contact. The stage has a light moving-part mass of 0.2126 kg. It is capable of generating translation of 300 pm in the x-, y- and z- axes, and rotation of 3 mrad about the three orthogonal axes. The stage demonstrates position resolution better than 5 nm rms and position noise less than 2 nm rms. The total power consumption by all the actuators is only a fraction of a watt. Experimental results presented in this paper show that the stage can carry, orient, and precisely position a payload as heavy as 0.3 kg. The pull-out force was found to be 8.08 N in the vertical direction. Furthermore, under the effect of a load variation of 0.14 N, the plant recovers its regulated position within 0.6 s. All these experimental results match quite closely with the calculated values because of the accurate plant model and robust controller design. This device can be used as a positioning stage for numerous applications including photolithography for semiconductor manufacturing, microscopic scanning of delicate instruments, fabrication and assembly of nano-structures, and microscale rapid prototyping.