ILLUMINATION DESIGN FOR SCANNING MICROLITHOGRAPHY SYSTEMS

摘要

The illumination system for a scanner incorporates an excimer laser (12) whose square beam is incident upon a two-dimensional array of lenses (20). The light exiting the array is made incident on a long focal length lens (24). The combination of the array and the long focal length lens causes the resulting square beam at the focal length plane of the long focal length lens to have a substantially uniform intensity across its area. An array of cylindrical lenses (26) receives these nearly parallel rays and the light output therefrom is then made incident on a first positive lens (40) whose focal length is longer than the distance between the cylindrical lens array and the first positive lens. A second positive lens (44) is located at the focal length of the first positive lens. An oblong beam is produced to illuminate a reticle.