Patent ID: 8624182

Claim:
An electro-optical inspection apparatus for inspecting a surface of a sample using an electron beam, the electro-optical inspection apparatus comprising: an electron beam source; a primary electro-optical system comprising at least a primary lens for inducing a primary electron beam emitted from the electron beam source; a stage for mounting the sample thereon, the surface of the sample being irradiated with the primary electron beam induced through the primary electro-optical system; a secondary electro-optical system comprising at least a secondary lens and an aperture for defining a numerical aperture (NA), and for inducing secondary electrons and mirror electrons, the secondary electrons being emitted from the sample surface when irradiating the sample surface with the primary electron beam, and the mirror electrons being reflected from the sample surface and a vicinity thereof when irradiating the sample surface with the primary electron beam; a detector for detecting at least either of the secondary electrons or the mirror electrons induced through the secondary electro-optical system; a first power source for supplying a first voltage to the sample mounted on the stage; at least a first electrode located to surround the sample mounted on the stage, for collecting dusts or particles; and a second power source for supplying a second voltage to the first electrode, wherein the second voltage has the same polarity as that of the first voltage and an absolute value which is equal to or larger than that of the first voltage, wherein the electron beam source emits the primary electron beam, a cross-section of which has a substantial area, and wherein the electro-optical inspection apparatus further comprises: an energy control means for setting an energy of the electron beam directed to the sample surface and an energy supplied to the sample such that electrons directed from the sample surface to a detector are within a transition band which contains mirror electrons and secondary electrons; and an aperture adjustment mechanism for adjusting a location of at least an aperture on a plane perpendicular to an axis of the secondary electro-optical system of the electro-optical inspection apparatus, so that electrons from a conductive material region of the sample surface and electrons from a nonconductive material region of the sample surface are selectively induced to the detector.