FOREIGN MATTER DETECTION OPTICAL SYSTEM FOR RETICLE MASK

摘要

PURPOSE:To provide the foreign matter detection optical system which detects only foreign matter without detecting a wiring pattern by utilizing the features of the directivity of scattered light from the foreign matter and scattered light from the wiring pattern of a reticle by a reticle foreign matter detection device. CONSTITUTION:The features of the directivity of the scattered light from the foreign matter and the scattered light from the wiring pattern of the reticle are taken into consideration, and two projection systems project laser beams opposite each other at a low angle; and both the laser beams are scattered by the foreign matter in all directions, so the scattered light beams are transmitted through the transmission part of a spatial filter and detected by a CCD element while the quantity of received light is increased. The laser beam which is projected on the wiring pattern and scattered with large directivity in projection direction is cut off by the spatial filter and not detected and the scattered light from the wiring pattern is excluded in the reticle foreign matter inspection device, so that only the foreign matter can surely be detected.