| CPC H01J 37/1478 (2013.01) [G06T 3/40 (2013.01); G06T 7/33 (2017.01); G06T 7/38 (2017.01); G06T 7/596 (2017.01); G06T 7/73 (2017.01); G06V 10/25 (2022.01); G06V 20/50 (2022.01); H01J 37/222 (2013.01); H01J 37/28 (2013.01); H01J 37/305 (2013.01); G06T 2207/10012 (2013.01); G06T 2207/10061 (2013.01); G06T 2207/30204 (2013.01); H01J 2237/2611 (2013.01); H01J 2237/2815 (2013.01); H01J 2237/31749 (2013.01)] | 20 Claims |

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1. A method of determining a depth of a hole milled into a first region of a sample, the method comprising:
positioning the sample in a processing chamber having a charged particle beam column;
milling a hole in the first region of the sample using a charged particle beam generated by the charged particle beam column;
identifying a first registration mark at an upper level of the milled hole;
identifying a second registration mark at a lower level of the milled hole;
taking a first set of images at a first tilt angle, the first set of images including a first image taken with a field of view that captures the first registration mark but not the second registration mark, and a second image taken with a field of view that captures the second registration mark but not the first registration mark;
taking a second set of images at a second tilt angle, different than the first tilt angle, the second set of images including a third image taken with a field of view that captures the first registration mark but not the second registration mark, and a fourth image taken with a field of view that captures the second registration mark but not the first registration mark; and
using stereoscopic measurement techniques to determine the depth of the hole based on the first and second sets of images.
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