Detection and correction of system responses in real-time

1. A method, comprising:

emitting an electron beam towards a specimen;

modulating the electron beam to obtain a beam signal, wherein the modulating is based on a wave that controls the beam signal, and wherein the modulating includes adjusting a beam current that reaches the specimen;

detecting, using an electron detector, secondary and/or backscattered electrons emitted by the specimen to obtain electron data, wherein the electron data defines a detection signal;

determining, using a processor, a comparison between the wave controlling the beam signal and a wave for the detection signal; and

filtering, using the processor, the detection signal based on the comparison.

2. The method of claim 1 , wherein the method further comprises:

applying a high-pass filter to the detection signal to obtain backscattered electron data.

3. The method of claim 2 , wherein filtering the detection signal further includes subtracting the backscattered electron data from the electron data to obtain secondary electron data.

4. The method of claim 2 , wherein filtering the detection signal further includes determining a relative fraction that is a ratio of an intensity of the backscattered electron data compared to an intensity of the electron data.

5. The method of claim 2 , further comprising:

detecting, using an opposing electron detector, secondary and/or backscattered electrons emitted by the specimen to obtain opposing electron data;

comparing, using the processor, the electron data and the opposing electron data to generate tilt data; and

changing a tilt of the electron beam using the tilt data.

6. The method of claim 1 , wherein the modulating includes changing the beam current of the electron beam.

7. The method of claim 1 , wherein the modulating includes switching the electron beam between being on and off.

8. The method of claim 1 , wherein the modulating includes directing the electron beam between a beam dump and the specimen.

9. The method of claim 1 , wherein the modulating further includes deflecting the electron beam across the specimen.

10. A system, comprising:

an electron beam tool including:

an electron beam emitter configured to emit electrons in an electron beam towards a specimen;

a stage configured to hold the specimen;

an electron detector configured to detect secondary and/or backscattered electrons emitted by the specimen to obtain electron data, wherein the electron data defines a detection signal; and

a controller in electronic communication with the electron beam tool, the controller having a processor;

wherein the controller is configured to:

instruct the electron beam emitter to modulate the electron beam to obtain a beam signal wherein the modulating is based on a wave that controls the beam signal, and wherein the modulating includes adjusting a beam current that reaches the specimen;

determine a comparison between the wave controlling the beam signal and a wave for the detection signal; and

filter the detection signal using the comparison.

11. The system of claim 10 , wherein the controller is further configured to:

apply a high-pass filter to the detection signal to obtain backscattered electron data.

12. The system of claim 11 , wherein the controller is configured to filter the detection signal further by subtracting the backscattered electron data from the electron data to obtain secondary electron data.

13. The system of claim 11 , wherein the controller is configured to filter the detection signal further by:

determining a relative fraction that is a ratio of an intensity of the backscattered electron data compared to an intensity of the electron data.

14. The system of claim 10 , further comprising:

an opposing electron detector configured to detect secondary and/or backscattered electrons emitted by the specimen to obtain opposing electron data; and

wherein the controller is further configured to:

compare the electron data and the opposing electron data to generate tilt data; and

change an angle of the electron beam emitter using the tilt data, thereby changing a tilt of the electron beam.

15. The system of claim 10 , wherein the controller is configured to modulate the electron beam by instructing the electron beam emitter to change the beam current of the electron beam.

16. The system of claim 10 , wherein the controller is configured to modulate the electron beam by instructing the electron beam emitter to switch the electron beam on and off.

17. The system of claim 10 , wherein the controller is configured to modulate the electron beam by instructing the electron beam emitter to direct the electron beam between a beam dump and the specimen.

18. The system of claim 10 , wherein the controller is further configured to modulate the electron beam by instructing the electron beam emitter to deflect the electron beam across the specimen.

19. A non-transitory computer-readable storage medium, comprising one or more programs for executing the following steps on one or more computing devices:

instructing an electron beam tool to emit an electron beam towards a specimen;

modulating the electron beam to obtain a beam signal, wherein the modulating is based on a wave that controls the beam signal, and wherein the modulating includes adjusting a beam current that reaches the specimen;

receiving electron data from an electron detector detecting secondary and/or backscattered electrons emitted by the specimen, wherein the electron data defines a detection signal;

determining a comparison between the wave controlling the beam signal and a wave for the detection signal; and

filtering the detection signal based on the comparison to obtain a filtered detection signal.

20. The non-transitory computer-readable storage medium of claim 19 , wherein the one or more programs are further configured to execute, on one or more computing devices:

training a machine-learning algorithm using the beam current, the electron data, and the filtered detection signal.