Patent ID: 11908657
Assignee: ZHONGKE JINGYUAN ELECTRON LIMITED
Field: Measurement (Instruments)
Classification: CPC H  G | IPC G  H

Claim 17:
18. A scanning electron microscope device for a sample to be detected, which is configured to project an electron beam to a surface of the sample to generate backscattered electrons and secondary electrons, comprising:
an electron beam source configured to emit along an optical axis thereof the electron beam;
a deflection mechanism, comprising:
a first deflector comprising a pair of electrodes and located downstream of the electron beam source; and
a second deflector located downstream of the first deflector, and an objective lens assembly, comprising:
an excitation coil which is energized to create a magnetic field; and
a magnetic yoke, formed by a magnetizer material as a housing which opens towards the sample, and comprises:
a hollow body defining an internal chamber where the excitation coil is accommodated; and
at least one inclined portion extending inward from the hollow body at an angle with reference to the hollow body and directing towards the optical axis, with an end of the at least one inclined portion being formed into a pole piece, and

a third deflector comprising a pair of electrodes and located between the second deflector and the objective lens assembly and disposed in an opening delimited and circumscribed by the pole piece, wherein each of the first deflector, the second deflector and the third deflector is an electrostatic deflector,
wherein the deflection mechanism further comprises a compensation electrode, which is located between the pole piece and the surface of the sample and is configured to adjust a focusing position of the electron beam at which the electron beam is focused, in a condition of excitation thereof with a voltage being applied thereon, by adjusting the voltage, and
wherein:
the pole piece is an end of the inclined portion of the magnetic yoke substantially disposed parallel to the optical axis, and a length of each electrode of the third deflector is of the same order of magnitude as a thickness of the pole piece but is not smaller than the thickness of the pole piece; or
the electrodes of the third deflector are arranged at a predetermined angle relative to electrodes of the first deflector, and the predetermined angle is set such that an off-axis aberration of the electron beam which is subject to deflection applied by the third deflector is minimized.