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

Our NRUSM (non-resonant type ultrasonic motor) driven 300 mm stroke precision stage for LSI manufacturing devices has achieved 0.69 nm control resolution and positioning performances. The results reveal the quick-response high-tracking ability of the NRUSM due to the piezoelectric effect. The sub-nanometer order physical displacement is totally controlled by the applied voltage. Although an extra precise positioner was needed for long stroke and high velocity conventional magnetic motor driven stages to achieve nanometer positioning, our actuator enables the stage to achieve high feeding velocity and high accuracy positioning simultaneously. The NRUSM is composed of 8 stack-type piezoelectric actuators, and by applying the appropriate control sequence infinite feeding becomes possible.