Patent ID: 7423267

Claim:
An electron beam apparatus comprising: an electron gun for emitting a plurality of primary electron beams; a primary electro-optical system for irradiating a sample with the primary electron beams emitted from the electron gun; a detector for detecting a plurality of secondary electron beams generated from the sample by the irradiation of the primary electron beams to evaluate the sample; and a secondary electro-optical system for directing the secondary electron beams from the sample to the detector, wherein the electron gun comprises a cylindrical cathode having, at its end facing the primary electro-optical system, and a plurality of emitter regions comprising a plurality of emitter chips for emitting the primary electron beams, respectively, and arranged such that when the center of each chip is projected onto a straight line in the X direction orthogonal to the center line of the bottom surface of said cathode, the projected emitter regions are spaced at substantially equal intervals.