US 12,334,300 B2
Focused ion beam system and method of correcting deviation of field of view of ion beam
Yuichiro Ohori, Tokyo (JP); and Keiji Tajima, Tokyo (JP)
Assigned to JEOL Ltd., Tokyo (JP)
Filed by JEOL Ltd., Tokyo (JP)
Filed on Jan. 19, 2023, as Appl. No. 18/099,127.
Claims priority of application No. 2022-007051 (JP), filed on Jan. 20, 2022.
Prior Publication US 2023/0230801 A1, Jul. 20, 2023
Int. Cl. H01J 37/304 (2006.01); H01J 37/10 (2006.01); H01J 37/21 (2006.01); H01J 37/305 (2006.01)
CPC H01J 37/304 (2013.01) [H01J 37/10 (2013.01); H01J 37/21 (2013.01); H01J 37/305 (2013.01); H01J 2237/0492 (2013.01); H01J 2237/2448 (2013.01); H01J 2237/30483 (2013.01); H01J 2237/31749 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A focused ion beam system for irradiating a sample with a focused ion beam to mill the sample, said focused ion beam system comprising:
an ion source for producing an ion beam;
a lens system which includes an objective lens having a strength and which is operative to focus the ion beam as the focused ion beam onto the sample such that secondary electrons are produced from the sample;
a detector for detecting the secondary electrons; and
a controller for controlling the lens system;
wherein the controller operates i) to provide control so that a focus of the ion beam is varied by directing the ion beam onto the sample without scanning while varying the strength of the objective lens, ii) to measure a signal intensity from the secondary electrons produced from the sample during the variation of the strength of the objective lens, iii) to adjust the focus of the ion beam based on a level of the strength of the objective lens which occurs when the measured signal intensity from the secondary electrons is minimal, iv) to acquire a secondary electron image containing an image of a trace of a spot formed on the sample when the focus of the ion beam is adjusted, and v) to correct deviation of a field of view of the ion beam based on a difference between a reference position of the secondary electron image and a position of the trace of the spot.