Patent ID: 8822911

Claim:
A focused ion beam apparatus comprising: an ion source configured to supply ions; a condenser lens configured to condense an ion beam extracted from the ion source, the condenser lens including a bipotential lens including: a first electrode configured to extract the ion beam from the ion source in response to application of an extracting voltage between the first electrode and the ion source, and a second electrode configured to condense the ion beam extracted from the ion source in response to application of a condenser voltage between the second electrode and the ion source; a plurality of types of apertures having different aperture diameters and configured to reduce a diameter of the condensed ion beam; and a control portion including a condenser voltage table configured to store a setting value of the condenser voltage for obtaining a reference ion beam current at which the ion beam diameter is minimized in correspondence with an amount of the extracting voltage and the types of the apertures and being configured to set the condenser voltage based on the condenser voltage table, wherein the control portion is configured to: store in advance, in the condenser voltage table, a calculation value of the condenser voltage for obtaining the reference ion beam current for each of the plurality of types of the apertures, obtain, for a reference aperture among the plurality of types of the apertures, an experimental value of the condenser voltage for obtaining the reference ion beam current, obtain a correction value of the condenser voltage by subtracting the calculation value stored for the reference aperture from the experimental value for the reference aperture, obtain the setting values for each of the plurality of types of the apertures by adding the obtained correction value to the calculation values stored for each of the plurality of types of the apertures, and store the obtained setting values in the condenser voltage table.