altThe UX4-LEDs projection exposure system from USHIO America, Inc. (Cypress, CA) is for manufacturing LED chips. The system allows full-field exposure of 6-inch wafers while preventing wafer warpage or distortion — achieving a throughput enhancement of 300% compared with conventional stepper systems. It requires neither mask replacement nor cleaning that would cause system downtime, and allows enhancement of detection accuracy of alignment marks with low visibility, such as those for transparent electrodes, to achieve high overlay accuracy. A modular structure for major system components allows easy specification changes or upgrading and easy maintenance.