| CPC H01J 37/3056 (2013.01) [H01J 37/20 (2013.01); H01J 2237/31745 (2013.01); H01J 2237/31749 (2013.01)] | 13 Claims |

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1. An ion milling apparatus comprising:
an ion source;
a sample stage on which a sample to be processed by being irradiated with an unfocused ion beam from the ion source is placed;
a measurement member holding unit that holds a linear ion beam current measurement member extending in a first direction; and
a control unit, wherein
a covering material is provided so as to cover at least a surface of the measurement member holding unit and the sample stage facing the ion source,
a material of the covering material contains, as a main component, an element having an atomic number smaller than that of an element of a material of a structure on which the covering material is provided, and
the control unit is configured to move the ion beam current measurement member in an irradiation range of the ion beam on a trajectory, which is located between the ion source and the sample stage and extends in a second direction orthogonal to the first direction, in a state where the ion beam is output from the ion source under a first irradiation condition, and measure an ion beam current flowing through the ion beam current measurement member when the ion beam current measurement member is irradiated with the ion beam.
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