Charged particle beam device with dark field detector

摘要

The charged particle beam device of this invention has a source of charged particles, and a charged particle optical system for focusing primary charged particle beams (3) emitted from said source and scanning the primary charged beams (3) on a sample (14). The device comprises a transmitted signal conversion member (15) for emitting secondary charged particles (12a, 12b) by collisions of dark field charged particles (18b) transmitted through the sample (14). An opening is formed in said transmitted signal conversion member (15) which opening has a size through which the transmitted charged particles (18b) can pass. The device further comprises a power supply capable of applying a positive voltage (Vc) to said opening. By controlling the positive voltage, the lower limit of the scattering angle of the dark field signal detected by a detector (13) can be controlled.