Patent ID: 7394523
Filing Date: 2008-07-01
Classification: G03F

Abstract:
1. An exposure apparatus that performs an exposure process in which an image of a pattern is transferred to a substrate, said apparatus comprising: a light source that emits light; a lens positioned to transmit the emitted light and focus the light onto an image plane; a reticle or mask bearing the pattern an image of which is to be transferred to the substrate, the reticle or mask operatively interposed between said light source and said lens in the apparatus such that the image of the pattern is transmitted by the light through said lens; and electronic controls comprising a memory in which leveling data representing errors in the focus of the lens and a threshold value are stored, and an interlock generator including a data processor that calculates a defocus value, indicative of the defocus associated with the lens, from the leveling data, a comparator that compares the defocus value with the threshold value during the exposure process, and a signal generator that selectively generates an interlock signal based on the results of the comparison executed by the comparator.