Measuring apparatus and method of setting observation condition

1. A measuring apparatus that irradiates a sample with a charged particle beam to observe the sample, comprising:

a particle source that outputs the charged particle beam;

a lens that collects the charged particle beam;

a detector that detects signals of emitted electrons emitted from the sample which is irradiated with the charged particle beam; and

a control device that controls the output of the charged particle beam to be a pulsed charged particle beam and the detection of the signal of the emitted electrons in accordance with an observation condition,

wherein the control device is configured to

set the observation condition based on user input;

set a first parameter of the observation condition for controlling an irradiation cycle of the charged particle beam;

set a second parameter of the observation condition for controlling a pulse width of the pulsed charged particle beam;

set a third parameter of the observation condition for controlling detection timing of the signal of the emitted electron within the irradiation time of the pulsed charged particle beam, wherein the third parameter is determined in accordance with a difference in intensity of signals of a plurality of emitted electrons emitted from the irradiation position of the pulsed charged particle beam;

scan the pulsed charged particle beam across the sample in accordance with the observation condition while detecting the signals of the electrons emitted from the sample;

generate a potential contrast image of the sample having a fine structure; and

scan the pulsed charged particle beam using a pixel split control based on a pixel split number representing the irradiation cycle.

2. The measuring apparatus according to claim 1 , wherein the control device is further configured to

cause the particle source to periodically irradiate the sample with a pulsed charged particle beam having a predetermined pulse width in accordance with the first parameter and the second parameter;

record data indicating a temporal change in intensity of the signals of the plurality of emitted electrons; and

determine the third parameter in accordance with a difference in intensity of the signals of the plurality of emitted electrons within the irradiation time.

3. The measuring apparatus according to claim 1 , wherein the control device is further configured to

set a fourth parameter indicating a characteristic of the sample;

use the first parameter, the second parameter, and the fourth parameter to simulate the signals of the plurality of emitted electrons emitted when the sample is periodically irradiated with the pulsed charged particle beam;

record data indicating a temporal change in intensity of the signals of the plurality of emitted electrons which are obtained from the simulation; and

determine the third parameter in accordance with a difference in intensity of the signals of the plurality of emitted electrons within the irradiation time.

4. The measuring apparatus according to claim 2 , wherein the control device is further configured to

set a plurality of candidate parameters to determine the detection timing;

obtain the signals of the emitted electrons detected at the detection timing corresponding to each of the plurality of candidate parameters with reference to the recorded data;

generate an image using the acquired signals of the emitted electrons; and

determine the candidate parameter to be set as the third parameter among the plurality of candidate parameters in accordance with an image corresponding to each of the plurality of candidate parameters.

5. The measuring apparatus according to claim 2 , wherein the control device is further configured to

identify a time at which the difference in intensity of the signals of the plurality of emitted electrons is maximum in accordance with the recorded data; and

set the third parameter in accordance with the identified time.

6. The measuring apparatus according to claim 2 , further comprising:

control mechanism that controls an electric field generated by charging of the sample,

wherein the control device is further configured to set a fifth parameter for controlling the control mechanism.

7. The measuring apparatus according to claim 4 , wherein the control device is further configured to

display a setting screen for setting parameters to be included in the observation condition; and

display the image on the setting screen.

8. A method of measuring a sample using an apparatus that irradiates the sample with a charged particle beam to observe the sample, the measuring apparatus including

a particle source that outputs the charged particle beam,

a lens that collects the charged particle beam,

a detector that detects signals of emitted electrons emitted from the sample which is irradiated with the charged particle beam, and

a control device that controls the output of the charged particle beam and the detection of signals of the emitted electron in accordance with an observation condition,

the method comprising

a first step of setting a first parameter of the observation condition, by the control device, to control an irradiation cycle of the charged particle beam;

a second step of setting a second parameter of the observation condition, by the control device, to control a pulse width of the charged particle beam to provide a pulsed charged particle beam; and

a third step of setting a third parameter of the observation condition, by the control device, to control detection timing of the signals of the emitted electrons within the irradiation time of the pulsed charged particle beam, wherein the third parameter is determined in accordance with a difference in intensity of signals of a plurality of emitted electrons emitted from the irradiation position of the pulsed charged particle beam;

a fourth step of scanning the pulsed charged particle beam across the sample in accordance with the observation condition while detecting the signals of the plurality of emitted electrons emitted from the sample;

a fifth step of generating a potential contrast image of the sample having a fine structure; and

a sixth step of scanning the pulsed charged particle beam using a pixel split control based on a pixel split number representing the irradiation cycle.

9. The method according to claim 8 , wherein

the third step comprises:

causing, by the control device, the particle source to periodically irradiate the sample with the pulsed charged particle beam having a predetermined pulse width in accordance with the first parameter and the second parameter;

recording, by the control device, data indicating temporal change in intensity of signal of the plurality of emitted electrons; and

determining, by the control device, the third parameter in accordance with a difference in intensity of the signals of the plurality of emitted electrons within the irradiation time.

10. The method according to claim 8 , wherein

the third step comprises;

setting, by the control device, a fourth parameter indicating a characteristic of the sample;

using, by the control device, the first parameter, the second parameter, and the fourth parameter to simulate the signals of the plurality of emitted electrons emitted when the sample is periodically irradiated with the pulsed charged particle beam;

recording, by the control device, data indicating a temporal change in intensity of the signals of the plurality of emitted electrons which is obtained from the simulation; and

determining, by the control device, the third parameter in accordance with a difference in intensity of the signals of the plurality of emitted electrons within the irradiation time.

11. The method according to claim 9 , wherein

the step of determining the third parameter comprising:

setting, by the control device, a plurality of candidate parameters to determine the detection timing;

acquiring, by the control device, the signal of the emitted electron detected at the detection timing corresponding to each of the plurality of candidate parameters with reference to the recorded data;

generating, by the control device, an image using the acquired signal of the emitted electrons; and

determining, by the control device, the candidate parameter to be set as the third parameter from among the plurality of candidate parameters in accordance with the image corresponding to each of the plurality of candidate parameters.

12. The method according to claim 9 , wherein

the step of determining the third parameter comprises;

identifying, by the control device, a time at which the difference in intensity of signals of the plurality of emitted electrons is maximum in accordance with the recorded date; and

setting, by the control device, the third parameter in accordance with the time.

13. The method according to claim 9 , further comprising:

an electric field generated by charging of the sample; and

setting, by the control device, a fifth parameter for controlling the electric field.

14. The method according to claim 11 , further comprising:

displaying, by the control device, a setting screen for setting the parameter to be included in the observation condition; and

displaying, by the control device, the image on the setting screen.

15. The method according to claim 10 , wherein

the step of determining the third parameter comprises:

setting, by the control device, a plurality of candidate parameters to determine the detection timing;

acquiring, by the control device, the signal of the emitted electron detected at the detection timing corresponding to each of the plurality of candidate parameters with reference to the recorded data;

generating, by the control device, an image using the acquired signal of the emitted electrons; and

determining, by the control device, the candidate parameter to be set as the third parameter from among the plurality of candidate parameters in accordance with the image corresponding to each of the plurality of candidate parameters.

16. The method according to claim 10 , wherein

the step of determining the third parameter comprises:

identifying, by the control device, a time at which the difference in intensity of signals of the plurality of emitted electrons is maximum in accordance with the recorded date; and

setting, by the control device, the third parameter in accordance with the time.

17. The method according to claim 10 , further comprising:

an electric field generated by charging of the sample; and

setting, by the control device, a fifth parameter for controlling the electric field.