Charged particle beam apparatus including aberration corrector
AssigneeHitachi High-Technologies Corporation
InventorsKotoko HIROSE, Takeshi Kawasaki, Tomonori Nakano
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Abstract
A focused charged particle beam apparatus including an aberration corrector, capable of finding the absolute value of the aberration coefficient at high speed, and capable of making high-accuracy adjustments at high speed. A deflection coil tilts the input beam relative to the object point, and measures the defocus data and aberration quantity at high speed while the beam is tilted from one image, and perform least squares fitting on these results to find the absolute value of the aberration coefficient prior to tilting the beam, and to adjust the aberration corrector.
Claims12
A charged particle beam apparatus comprising:
- a charged particle optical system to scan a primary charged particle beam on a specimen, detect secondary charged particles emitted from the specimen due to the scanning and output the detection results as a secondary charged particle signal;
- a control unit for the charged particle optical system;
- an data processing device to process the secondary charged particle signal that was output and acquire two-dimensional distribution information on pixels matching the area scanned by the primary charged particle beam,
- wherein the charged particle optical system includes:
- an aberration corrector to reduce the aberration generated by the charged particle optical system;
- and
- a unit to guide the charged particle beam from the optical axis of the charged particle beam in a tilted state onto the specimen, and
- wherein the data processing device:
- calculates the out-of-focus amount and astigmatic difference in the charged particle optical system from the multiple two-dimensional distribution information acquired by scanning the specimen with the primary charged particle in a tilted state and also while changing the degree of focus and,
- calculates an optional order aberration coefficient to use in the charged particle optical system, by utilizing the two-dimensional distribution information obtained from scanning the specimen in a state where the primary charged particle beam is not tilted, and the calculated out-of-focus amount and astigmatic difference.
Dependencies are inferred from the claim text.