| 摘要 |
PURPOSE:To measure potential with high accuracy by preparing foundation information without irradiating electron beams and subtracting the foundation informations from detecting secondary electronic signals. CONSTITUTION:Secondary electrons from a sample 16 are detected 19, amplified 20, A/D converted and fed to a subtracter 22. A beam irradiating point is computed from deflection signals 15 and deflection central coordinates in a chip coordinate system, and coordinate informations are transmitted over a foundation determing section 25 to which a pattern information memory 24 is connected. The pattern information memory 24 is searched on the basis of the coordinate information, and the kind of a foundation at a beam irradiating position is decided to be a wiring such as an Al wiring. Foundation informations in the case when driving signals are not added to the sample 16 and pulse beams are applied to the foundation are communicated previously with a foundation compensating information compensating memory 26, a compensating value is determined 27 through the determination of the foundation, and the compensating value is subtracted 22 from digital informations 22 and displayed 28. According to the constitution, the variation of detecting secondary electronic signal levels due to the difference of the foundations is corrected automatically, and potential distribution can be measured with high accuracy. |
