Patent ID: 8188443
Filing Date: 2012-05-29
Classification: B82Y,H01J

Abstract:
1. A focusing method of a charged particle beam comprising: measuring a first set value of a lens coil when the beam is focused at a reference level on a calibration mark using the lens coil; measuring a second set value of the lens coil when the beam is focused at an another level, which is different from the reference level, on the calibration mark using the lens coil; acquiring a first conversion factor for changing a focused level with the lens coil using the first set value and the second set value; measuring a third set value of an electrostatic lens when the beam is focused at the reference level on the calibration mark using the electrostatic lens; acquiring a fourth set value of the electrostatic lens when the beam is focused at an another level, at which the lens coil has changed a focal point position, using the electrostatic lens; acquiring a second conversion factor for changing a focused level with the electrostatic lens using the third set value and the fourth set value; measuring a level distribution across a surface of a target object; focusing the beam at an intermediate level position of the level distribution of the surface of the target object with the lens coil by correcting the first set value of the lens coil using the first conversion factor; and focusing the beam at a selected level position of the level distribution of the surface of the target object with an electrostatic lens by correcting a set value of the electrostatic lens using the second conversion factor, from the intermediate level position focused at with the lens coil.