Patent ID: 6841402
Filing Date: 2005-01-11
Classification: H01J,Y10S

Abstract:
1. In a method for performing charged-particle-beam (CPB) microlithography of a specimen of which a surface has a crystal-lattice orientation, and an alignment mark is formed on the surface, a method for detecting a position of the alignment mark, comprising: irradiating a charged particle beam onto an area of the specimen surface having the crystal-lattice orientation but at which the alignment mark is not present, and detecting backscattered charged particles propagating from the irradiated area, so as to obtain a first backscattered-particle signal; storing data in the first backscattered-particle signal in a memory; irradiating the charged particle beam onto the alignment mark, and detecting backscatter charged particles propagating from the irradiated alignment mark, so as to obtain a second backscattered-particle signal; recalling in the stored data from the memory and subtracting the recalled data from the second backscattered-particle signal to obtain a difference signal; and determining the alignment-mark position from the difference signal.