Automated application of drift correction to sample studied under electron microscope

Patent metadata

Field	Value
Publication number	US-11902665-B2
Application number	US-202217585222-A
Country	US
Kind code	B2
Filing date	Jan 26, 2022
Priority date	Aug 16, 2019
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

Methods and systems for calibrating a transmission electron microscope are disclosed. A fiducial mark on the sample holder is used to identify known reference points so that a current collection area and a through-hole on the sample holder can be located. A plurality of beam current and beam area measurements are taken, and calibration tables are extrapolated from the measurements for a full range of microscope parameters. The calibration tables are then used to determine electron dose of a sample during an experiment at a given configuration.

First claim

What is claimed is:

1. A method for measuring electron dose in a sample with a transmission electron microscope (TEM), the method comprising:
taking multiple measurements of the area of an electron beam of the TEM and the amount of current produced by the electron beam of the TEM,
wherein the TEM has different condenser lens settings for the multiple measurements of the area of the electron beam and the amount of current produced by the electron beam;

using the electron beam to excite the sample during an experiment performed on the sample using the TEM, wherein the TEM is set with particular condenser lens settings;
determining a beam area and a beam current of the electron beam used to excite the sample during the experiment for the particular condenser lens settings of the TEM based on the multiple measurements of the area of the electron beam and the amount of current produced by the electron beam; and
measuring an electron dose rate on the sample during the experiment based on the determined beam area and the determined beam current for the particular condenser lens settings of the TEM.

2. The method of claim 1 , wherein the area of the electron beam of the TEM is determined based on an image of the electron beam on a fluorescent screen of the TEM.

3. The method of claim 1 , wherein the area of the electron beam of the TEM is determined based on an image of the electron beam on a camera of the TEM.

4. The method of claim 1 , wherein the area of the electron beam of the TEM is determined based on one or more points identified at an edge of the electron beam.

5. The method of claim 1 , wherein the area of the electron beam of the TEM is determined using machine vision to identify the electron beam.

6. The method of claim 1 , wherein the amount of current produced by the electron beam of the TEM is determined using a current collector of the TEM, wherein the current collector of the TEM includes a fluorescent screen, a Faraday cup, or a TEM camera.

7. The method of claim 1 , wherein the multiple measurements are taken with the TEM set at different aperture settings for the electron beam.

8. The method of claim 1 , wherein the multiple measurements are taken with the TEM set at different acceleration voltage settings, convergence angles, emission currents, spot size, extraction voltages, or intensity settings for the electron beam.

9. The method of claim 1 , further comprising calculating the electron dose based on the measured electron dose rate at a specific area over a specific amount of time.

10. The method of claim 1 , wherein the electron dose on the sample is measured at a point in time during the experiment based on the determined beam area and the determined beam current for the particular condenser lens setting of the TEM during the point of time at which the electron dose is measured.

11. A microscope control system for measuring electron dose in a sample with a transmission electron microscope (TEM), the system comprising:
a processor configured for:
taking multiple measurements of the area of an electron beam of the TEM and the amount of current produced by the electron beam of the TEM,
wherein the TEM has different condenser lens settings for the multiple measurements of the area of the electron beam and the amount of current produced by the electron beam;

using the electron beam to excite the sample during an experiment performed on the sample using the TEM, wherein the TEM is set with particular condenser lens settings;
determining a beam area and a beam current of the electron beam used to excite the sample during the experiment for the particular condenser lens settings of the TEM based on the multiple measurements of the area of the electron beam and the amount of current produced by the electron beam; and
measuring an electron dose rate on the sample during the experiment based on the determined beam area and the determined beam current for the particular condenser lens settings of the TEM.

12. The microscope control system of claim 11 , wherein the area of the electron beam of the TEM is determined based on an image of the electron beam on a fluorescent screen of the TEM.

13. The microscope control system of claim 11 , wherein the area of the electron beam of the TEM is determined based on an image of the electron beam on a camera of the TEM.

14. The microscope control system of claim 11 , wherein the area of the electron beam of the TEM is determined based on one or more points identified at an edge of the electron beam.

15. The microscope control system of claim 11 , wherein the area of the electron beam of the TEM is determined using machine vision to identify the electron beam.

16. The microscope control system of claim 11 , wherein the amount of current produced by the electron beam of the TEM is determined using a current collector of the TEM, wherein the current collector of the TEM includes a fluorescent screen, a Faraday cup, or a TEM camera.

17. The microscope control system of claim 11 , wherein the multiple measurements are taken with the TEM set at different aperture settings for the electron beam.

18. The microscope control system of claim 11 , wherein the multiple measurements are taken with the TEM set at different acceleration voltage settings, convergence angles, emission currents, spot size, extraction voltages, or intensity settings for the electron beam.

19. The microscope control system of claim 11 , wherein the processor is further configured for calculating the electron dose based on the measured electron dose rate at a specific area over a specific amount of time.

20. The microscope control system of claim 11 , wherein the electron dose on the sample is measured at a point in time during the experiment based on the determined beam area and the determined beam current for the particular condenser lens setting of the TEM during the point of time at which the electron dose is measured.

Assignees

• Protochips Inc

Inventors

• Walden Ii Franklin Stampley
• Damiano Jr John
• Nackashi David P
• Gardiner Daniel Stephen
• Uebel Mark
• Franks Alan Philip
• Jacobs Benjamin
• Friend Joshua Brian
• Marusak Katherine Elizabeth
• Marthe Jr Nelson L
• Larson Benjamin Bradshaw

Classifications

• H04N23/695 Primary

  Control of camera direction for changing a field of view, e.g. pan, tilt or based on tracking of objects · CPC title

• G06T7/215

  Motion-based segmentation · CPC title

• G06T7/337

  involving reference images or patches · CPC title

• H01J37/20

  Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support · CPC title

• G06T2207/10061

  from scanning electron microscope · CPC title