Ultra Precision Positioning Devices for Lithography

New integrated circuit fabrication technologies will require rapid positioning, with accuracies in the nanometer range, over a workspace spanning hundreds of millimeters. This will require a two-stage mechanism: One stage capable of moving over a large span, carrying a smaller "mini-actuator." As the first stage approaches the desired position, the second stage actuator will take over and do the final positioning. The key to fast and accurate positioning combines several elements: Fast and controllable short stroke actuation; rapid long stroke actuation; low noise sensors; and control systems. Magnetostrictive actuators lend themselves well to the short stroke actuator. A high performance capacitive gauge will be used for feedback. Voice coil actuators are an established technology for rapid, large motions. Optical scales using diffraction interpolation are available with nanometer repeatability. These are suitable as long range sensors. A control system for a dual-actuator, one-axis ultraprecision positioner would use an LQR design, aimed at keeping the short stroke actuator near the center of its actuation span. In Phase I, we will design and build a one-axis positioner to demonstrate the dual-actuator. Anticipated Benefits: Rapid utlraprecision actuation is a key technology in all aspects of lithography. Nano lithography applications, important for commercial semiconductor fabrication, will benefit immediately from the techniques developed in this proposal. Speed of handling and therefore throughout will be enhanced.