Patent ID: 7888642

Claim:
An electron beam apparatus for irradiating a sample with a primary electron beam, and detecting secondary electrons generated from a surface of the sample by the irradiation to evaluate the sample surface, comprising: a primary electro-optical system for focusing the primary electron beam on the sample surface and scanning it with the primary electron beam; a secondary electro-optical system comprising at least one stage of lens; an E×B separator for separating the secondary electrons generated from the sample surface and directing them to the secondary electro-optical system; a first detector for detecting the secondary electrons which have passed through the secondary electro-optical system; a second detector for detecting an exposure dose of the primary electron beam on the sample surface; a memory for storing the detected exposure doses on the sample surface; and a control apparatus adapted to calculate a unit exposure dose per unit area on the basis of the stored exposure doses, and controlling the primary electron beam such that the unit exposure dose does not exceed a predetermined level.