Sub-nanometer resolution ultrasonic motor for 300 mm wafer lithography precision stage

This paper describes the development of the nonresonant ultrasonic motor (NRUSM) applied to a 300-min-stroke ultra-precision stage for future LSI manufacturing, in particular electron beam based technologies. Advantages of the NRUSM are high resolution, no magnetic noise generation, high servo rigidity and high retention, It is continued that the NRUSM is suitable for ultra-precision positioning, and slow- and high-velocity feeding at closed-loop controls. The performance of the NRUSM-driven stage includes; (1) 85 mm/s feed velocity With average acceleration 375 mm/s(2) over the 300 mm stroke at open-loop control; (2) +/-0.69 nm positioning accuracy at step and repeat response, 17 ms average positioning, time for 30 run positioning accuracy, positional error during constant velocity feeding below +/-1.5 nm for 1()() nm/s Bind 4 4()11111 for 20 mm/s. and velocity ripple at 36 mm/s is below 0.04% at closed-loop control.