Patent ID: 8124940

Claim:
A charged particle beam apparatus comprising: a charged particle source for emitting a charged particle beam; a condenser lens for focusing the charged particle beam emitted by the charged particle source; an objective lens for focusing the charged particle beam on a sample; a scanning deflector for scanning the sample with the charged particle beam; a detector for detecting an electron generated by irradiation of the charged particle beam on the sample; and a deflector for deflecting the charged particle beam, wherein the deflector has a mechanism capable of moving up and down, the deflector deflects the charged particle beams by two different deflection amounts at a plurality of positions to ensure that two sample images are obtained, and a displacement of one of the sample images from the position of the other image is measured, and the condenser lens adjusts the position of a focal point of the charged particle beam based on the displacement of the one of the sample images from the position of the other image to ensure that the focal point of the charged particle beam is located at a predetermined position.