Patent ID: 7964844

Claim:
A sample inspection apparatus, comprising: an electron beam apparatus for irradiating an electron beam on a sample to inspect the sample; optical focus value detection means including an optical microscope, for detecting a first focus value of the optical microscope which corresponds to a position of a surface of the sample in an optical axis direction; and converting means for converting the detected first focus value into a second focus value which is used in the electron beam apparatus when the sample is inspected by the electron beam apparatus, wherein the optical focus value detection means comprises auto-focus control means for automatically focusing the optical microscope on the surface of the sample and outputting the first focus value corresponding to a position of a focus lens in the optical axis direction of the optical microscope under a focused condition; and the converting means comprises means for receiving the first focus value from the auto-focus control means and converting the first focus value into the second focus value such that the second focus value corresponds to a voltage applied to a focus lens of the electron beam apparatus, wherein when a first focus value ZM n regarding a point of the sample surface is obtained, the converting means is adapted to calculate the following equation, using a previously obtained first focus value ZM 1 regarding another point of the sample surface and a previously obtained voltage ZEB 1 to be supplied to the focus lens of the electron beam apparatus regarding the latter point of the sample surface, to obtain a voltage ZEB n to be applied to the focus lens of the electron beam apparatus regarding the former point: ZEB n =ZM n *a where “a”=(ZEB 1 /ZM 1 ).