Novel piezo motor for a high precision motion axis

Abstract

The Semiconductor industry’s evolution towards 7, 5 and 3 nm nodes at higher throughputs, poses a challenge on motion systems. Motion systems are expected to yield a sub nanometer accuracy and velocity higher than 500 mm/sec, fast move and settle, low drift and minimal thermal load on the system, especially in vacuum. Ultrasonic piezo-motors have many benefits to fulfill these requirements. This paper reports on the development of a novel piezo motor, characterized by high velocity, high stiffness, low thermal load and ultra-high precision. The use of six motors, in parallel, on a single motion axis can yield a 200N of thrust force and a 60 N/μm stiffness. The motor is driven by a new driver having a noise equivalent position of better than 60 pico-meter. This paper reviews the motor design considerations, performance capabilities in stiffness, duty cycle, sub-nanometer convergence and ultra-low drift. Robustness is demonstrated by long term run. An example of a motion axis driven by the novel motor is shown.