| 摘要 |
PURPOSE:To correct various aberrations attendant on deflection, by arranging at least eight marks in the vicinity of a deflecting field on the surface of irradiation, while irradiating a charged corpuscular beam to these marks, in reference to a charged corpuscular beam allied unit. CONSTITUTION:Marks 1-8 are added to the vicinity of a deflecting field in advance. When a charged corpuscular beam 11 is scanned on each mark, a secondary charged corpuscular beam is generated from the sample face and the incident beam falls in a detector 16. At this moment, the generating value of the charged corpuscular beam from the top of the mark and from the outside of it is different so that if the value is checked by the detector 16, relationships between this signal value to a deflector 14 and the mark position and the converged size of the charged corpuscular beam, etc., are made out. This operation is carried out by a measuring system 17. For example, each factor is found by a factorial determination system 18 with a minimal square-law, etc. On a basis of this factor, when deflection is carried out at a desirable position, a correction signal 20 is to be found by this factor and accurate correction comes achieved by the detector 21. |
