US 12,463,009 B2
Method and system for studying samples using a scanning transmission charged particle microscope with reduced beam induced sample damage
Maarten Bischoff, Eindhoven (NL); and Bert Freitag, Eindhoven (NL)
Assigned to FEI Company, Hillsboro, OR (US)
Filed by FEI Company, Hillsboro, OR (US)
Filed on Jun. 29, 2022, as Appl. No. 17/853,727.
Claims priority of application No. 21182936 (EP), filed on Jun. 30, 2021.
Prior Publication US 2023/0005710 A1, Jan. 5, 2023
Int. Cl. H01J 37/28 (2006.01); H01J 37/20 (2006.01); H01J 37/26 (2006.01)
CPC H01J 37/28 (2013.01) [H01J 37/20 (2013.01); H01J 37/265 (2013.01); H01J 2237/2802 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method for examining a sample in a scanning transmission charged particle microscope, comprising the steps of:
providing a scanning transmission charged particle microscope, said scanning transmission charged particle microscope comprising:
a charged particle beam source for emitting a charged particle beam;
a sample holder for holding a sample;
an illuminator for directing the charged particle beam emitted from the charged particle source on said sample;
a scanning unit for scanning said beam onto a plurality of sample locations on said sample; and
a controller for controlling operations of the scanning transmission charged particle microscope;
characterized by
providing a desired dose parameter for at least a first sample location of said plurality of sample locations;
determining, using said controller, a first set of parameter settings for said illuminator and said scanning unit for substantially achieving said desired dose parameter at said first sample location, wherein said first set of parameter settings are determined using a numerical model based on the desired dose parameter, wherein the first parameter settings for said illuminator includes settings for a condenser lens of the illuminator, and the desired dose parameter includes a desired dose rate; and
providing a second desired dose parameter and determining, using said controller, a second set of parameter settings for said illuminator and said scanning unit for substantially achieving said second desired dose parameter, wherein determining the second set of parameter settings for said illuminator includes measuring a beam current upstream of the illuminator, and determining the second set of parameter settings using the numerical model, wherein the measured beam current and the second desired dose parameter are the input parameters of the numerical model.