0.69 nm resolution ultrasonic motor for large stroke precision stage

This study reports the application of the non-resonant type ultrasonic motor (NRUSM) to a 300 mm-stroke ultra-precision stage for the future nanoelectronics manufacturing. The advantages of the NRUSM are high resolution and no magnetic noise generation due to the DC characteristics of the piezoelectric device, and high servo rigidity and no additional brake mechanism needed due to direct drive mechanism. It is confirmed that the NRUSM is suitable for ultra-precision positioning, slow and high velocity feeding at closed-loop control. The NRUSM driven stage performance results are; (1) maximum velocity 50 mm/s over the 300 mm-stroke at open-loop control; (2) positioning accuracy of /spl plusmn/0.69 nm at step and repeat response, and position accuracy at constant velocity feeding 10 nm/s /spl sim/36 mm/s below 20 nm at closed-loop control.