Patent ID: 6930308

Claim:
An electron beam apparatus for inspecting a semiconductor specimen comprising: an electron beam device that is operable to direct an electron beam onto the semiconductor specimen thereby causing electrons to emanate from the semiconductor specimen; an electron beam column having a central axis, wherein the electron beam travels along the central axis until the electron beam becomes incident with the specimen; a first quadrapole set around the central axis and below the electron beam device, the first quadrapole configured to deflect the electron beam away from the central axis; a second quadrapole set around the central axis and below the first quadrapole, the second quadrapole configured to deflect the electron beam towards the central axis such that the electron beam is incident upon a designated area on the specimen regardless of the incident angle of the electron beam, wherein the first and the second quadrapoles deflect the electron beam such that the electron beam becomes incident upon the designated area at three or more different incident angles; a magnetic lens set around the central axis and located below the second quadrapole, the magnetic lens configured to focus the electron beam upon the specimen; and one or more detectors that are positioned above the semiconductor specimen and are configured to collect electrons emanating from the semiconductor specimen in response to the incident beam at the three or more incident angles, wherein the one or more detectors output data signals that correspond to the electrons collected by the detector; and an analysis module that is operable to receive the data signals from the detector, correlate the data signals, and construct a three dimensional image of the semiconductor specimen based on the electrons emanating from the specimen in response to the incident beam that is deflected at the three or more incident angles.