Patent US 7,329,889

An electron beam apparatus including a table which mounts a specimen and is movable in three dimensional directions, an electron beam optical system irradiating an electron beam onto a specimen and for detecting a secondary electron emanated from the specimen by the irradiation of the electron beam, and a surface height detection system for detecting height of the surface of the specimen mounted on the table. A focus control system controls a relative position between a focus position of the electron optical system and the table in accordance with information of the height, and an image processing system obtains an image from the detected secondary electron and processes the obtained image to detect a defect on the surface of the specimen.