| 1. A charged particle beam apparatus which illuminates a specimen with a charged particle beam focused thereon via a charged
particle optical system arranged in a column, wherein:
between the charged particle optical system and the specimen, there is provided a plate-like member having an electrically
conductive portion and an opening to transmit the charged particle beam; and
for the plate-like member to function as a charge preventive plate, the plate-like member is configured in such a manner that
the plate-like member is enough large to cover at least a part of the charged particle optical system when viewed from the
charged particle beam irradiation spot on the specimen, the plate-like member has a gas inflow path formed therein, and the
gas inflow path has gas injection outlets formed to inject gas toward the charged particle beam irradiation spot on the specimen.
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