FOCUSING DEVICE AND METHOD

摘要

PROBLEM TO BE SOLVED: To accurately detect a focus, to highly accurately measure and inspect even when the line width of a pattern on a semiconductor and the pitch of the pattern become equal to or below the wavelength of an optical system. SOLUTION: The focusing device includes: a first image forming optical system 30 for forming an optical image on an inspection sensor 40; a second image forming optical system 60 for branching the optical image from the first image forming optical system 30 toward an AF sensor 70, and also, branching the optical image into two to form a front focus image and a back focus image related to the optical image on the inspection sensor 40 on the AF sensor 70; a focus detection circuit 82 for detecting the optimum focal position based on the high region component of the front sensor image in the front focal position and the high region component of the back sensor image in the back focal position obtained from the AF sensor 70; and a focus control circuit 83 for controlling the focusing of the first imaging optical system 30 based on the focal position detected by the focus detecting circuit 82. COPYRIGHT: (C)2007,JPO&INPIT