| 摘要 |
PROBLEM TO BE SOLVED: To clean a charged particle optical system without disassembling or washing it or replacing components and to recover performance by deflecting and scanning a charged particle beam, and allowing charged particles to collide with the structure surface of the charged particle optical system when normal detection and measurement are made infeasible by the pollution of the charged particle optical system. SOLUTION: When the normal flight of ions is disabled by the pollution of an ion optical system and the ions reaching an ion detector 9 are decreased, a cleaning work instruction is applied to a computer and software 18, then Ar gas is introduced into an ionization chamber 2 from a gas cylinder 12, and Ar ions fly to a lens group 3. The pollution on the surfaces of the lens group 3 and a slit 4 is cleaned and removed by the Ar ions via a spattering action. After a fixed time, the objective slit 4 is fully opened to pass the Ar ions, the pollution on the inner wall section of a fan-shaped electromagnetic field 5 and the surface of a closed intermediate slit 6 is cleaned and removed, then the intermediate slit 6 is opened, and the surface pollution in a fan-shaped magnetic field 7 and a closed image forming slit 8 is cleaned and removed.
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