Patent ID: 7420167

Claim:
An apparatus for electron beam inspection with projection electron microscopy, comprising: an electron irradiation optics which converges and irradiates a planar electron beam obtained by shaping an electron beam emitted from an electron source, via an object lens to a surface of an object to be inspected; an electric-field generating unit which generates such an electric field that causes the planar electron beam irradiated from the electron irradiation optics to be drawn backward from neighborhood of the surface of the object to be inspected; an electron-imaging optics which images, as an electron beam image, electrons drawn backward from the neighborhood of the surface of the object by the electric field generated by the electric-field generating unit; an image detection unit which detects an inspection image signal by converting a focusing inspection image of the object into the inspection image signal, wherein the focusing inspection image is imaged by the electron-imaging optics; a focus position controller which controls a focus position of the objective lens so that the focusing inspection image of the object can be detected by the image detection unit; and a defect judgment unit which detects a defect formed on the object, by judgment processing the inspection image signal detected by the image detection unit; wherein the focus position controller further includes: a focus measure calculation unit which calculates focus measure from a plurality of image signals into which electron beam images imaged by the electron-imaging optics, at a plurality of focus positions different from one another in focus offsets, are converted by the image detection unit; a focus position calculation unit which calculates height of a confocal plane conjugate to a plane of convergence of the planar electron beam by the objective lens in relation to the electron-imaging optics, on the basis of the focus measure calculated by the focus measure calculation unit, and then calculates the focus position of the objective lens to detect the focusing inspection image of the object in the image detection unit, on the basis of the calculated height of the confocal plane; and a focus position correction unit which corrects the focus position of the objective lens according to the focus position thereof calculated by the focus position calculation unit.