Patent ID: 6844549

Claim:
An electron beam length-measurement apparatus for measuring a length of a predetermined portion of an object to be measured by using an electron beam, comprising: an electron gun operable to emit the electron beam; a deflecting unit operable to deflect the electron beam; an object holding unit to place the object thereon; a detector operable to detect electrons that are scattered by the electron beam; a memory operable to store, in advance, layout position information that specifies a layout position of the predetermined portion to be measured; an alignment scanning controller for controlling said deflecting unit to scan the object twice with the electron beam in one dimension of the object, obtaining a point at which the amount of electrons, successively detected by the detector, change for each scan, obtaining a line by connecting said obtained two points, and determining an alignment of the object upon comparing said obtained line with said layout position information; a length-measurement scanning controller operable to control said deflecting unit to scan the object once with the electron beam to allow the layout position of the predetermined portion to be irradiated with the electron beam, based on the layout position information; and a measurement unit operable to measure the length of the predetermined portion, based on a changing amount of the electrons successively detected by said detector while said length-measurement scanning controller scans the object.