Patent ID: 6195154
Filing Date: 2001-02-27
Classification: G03F

Abstract:
A projection exposure apparatus comprising:a projection optical system which projects a mask pattern onto a photosensitive substrate;a substrate stage which holds said substrate and positions said substrate in a plane perpendicular to an optical axis of said projection system;a focus leveling stage which adjusts an inclination of said substrate and a level of said substrate in a direction along the optical axis of said projection optical system;a focusing projection optical system which projects an image of a focus-detecting pattern onto a plurality of measurement points in an exposure area by said projection optical system obliquely relative to said optical axis of said projection optical system using a light to which said substrate is not sensitive;light-receiving optical system which collects the reflected lights from said plurality of measurement points to re-image said focus detecting pattern on said plurality of measurement points;a plurality of photoelectric detecting devices which generates detected signals corresponding to horizontal offset values of a plurality of images which are re-imaged by said light-receiving optical system; anda memory which stores information of a process structure of an exposure surface of said substrate; anda control device which obtains a positional relation between a plurality of stepped areas in said exposure area and said plurality of measurement points based on respective detection signals of said photoelectric detecting device corresponding to said plurality of measurement points and said process structure memorized in said memory and obtains separately for each of said plurality of measurement points an offset value for fitting one of said plurality of stepped areas to an image plane by said projection optical system with an operation device to control an operation of said focus leveling stage using said offset value.