Multi-axis gas bearing stage assembly

摘要: An improved multi-axis gas bearing stage assembly is disclosed which has a base, an intermediate element, stage, and control system for controlling the movement of element stage. The includes first second Y-axes positioning sub-systems differentially ends along motion, with respect to X i -axis sub-system element. In one embodiment, comprise motor-encoder driven leadscrews. linear motors, measuring scales, read heads. third motors interferometer systems. A method achieving orthogonality between Y- -axes that features alignment standard disclosed. another differential capability utilized θ-axis about Z-direction orthogonal both X-axes, rotationally aligning semiconductive wafer other embodiments, two methods kinematically within utilization apparatus are three retroreflectors mounted directly on chuck, located transport moves interferometers rotationally, maintain optical coupling retroreflectors. still five chuck axis eliminate all Abbe offset measurement errors in position wafer, placed upon X, Y, θ-axes motion.