Abstract: An electron beam apparatus comprises, inside of an objective lens for focussing a primary electron beam e1 and irradiating it on a sample surface, a secondary electron energy analyzer having a retarding mesh electrode for analyzing the energy of a secondary electron e2 emitted from a point on the sample surface at which the primary electron beam e1 is irradiated. The secondary electron energy analyzer comprises a collimation unit for forming one or more electrostatic lenses by a nonuniform electrical field distribution and for having an electrostatic lens collimate the trajectory of a secondary electron e2 for its injection into a retarding grids (mesh electrode). The collimation unit comprises at least three cylindrical electrodes positioned between the sample surface and the retarding grid (mesh electrode) and numbered first, second and third from the one closest to the sample surface.

Abstract: A method of measuring a voltage with an electron beam apparatus considers a change in a convergence factor due to a change in an S curve, as well as an error in a secondary electron signal level with a phase of measurement being scanned at random, to accurately measure the voltage. The method measures the voltage of a voltage measuring spot on a sample, prepares an analytic voltage by superimposing a probe voltage having an average of 0 V and no correlation with the measured voltage on the measured voltage, measures a secondary electron signal level with the analytic voltage, computes a convergence factor around a slice level set on the S curve according to a correlation between the secondary electron signal level and the probe voltage and according to an autocorrelation of the probe voltage, and updates the analytic voltage according to the convergence factor, thereby updating the measured voltage.

Abstract: A method of measuring a voltage with an electron beam apparatus considers a change in a convergence factor due to a change in an S curve, as well as an error in a secondary electron signal level with a phase of measurement being scanned at random, to accurately measure the voltage. The method measures the voltage of a voltage measuring spot on a sample, prepares an analytic voltage by superimposing a probe voltage having an average of 0 V and no correlation with the measured voltage on the measured voltage, measures a secondary electron signal level with the analytic voltage, computes a convergence factor around a slice level set on the S curve according to a correlation between the secondary electron signal level and the probe voltage and according to an autocorrelation of the probe voltage, and updates the analytic voltage according to the convergence factor, thereby updating the measured voltage.