Patent ID: 7408172

Claim:
A charged particle beam apparatus comprising a charged particle source and a charged particle optical system for focusing a charged particle beam emitted from the charged particle source and scanning a sample with the charged particle beam, the charged particle optical system further comprising: an objective lens for focusing the charged particle beam and irradiating the sample therewith; a second lens disposed between the objective lens and the charged particle source for irradiating the objective lens with the charged particle beam without producing a crossover between the objective lens and the second lens; a first deflector for deflecting the charged particle beam such that the beam passes through an off-axis of the objective lens so as to irradiate the sample from off the axis of the objective lens and with an inclination; and a second deflector for deflecting the charged particle beam in a direction opposite to the deflecting direction of the first deflector so as to cause the charged particle beam to pass through an off-axis of the second lens and to cancel a coma aberration produced by the objective lens and the second lens.