Charged particle beam device and method for correcting detected signal thereof
View Patent ↗A charged particle beam device of the present invention has a signal processing function of acquiring a secondary signal obtained when a charged particle beam is caused to scan at a low speed not subjected to a band limitation of an electrical signal path, and a secondary signal obtained when a charged particle beam is caused to scan at a high speed subjected to the band limitation of the electrical signal path, calculating a degradation function (H −1 (s)) between the plurality of secondary signals, and using an inverse function thereof as a correction filter; and a function of updating a parameter of the correction filter to an optimal value as needed or at given timing. Accordingly, the charged particle beam device can perform optimum image restoration even when a detector or an amplifier circuit that constitutes the electrical signal path degrades with time.
1. A charged particle beam device comprising:
a charged particle beam source that generates a charged particle beam;
means for detecting a secondary signal generated from a sample upon irradiation of the sample with the charged particle beam;
means for converting the secondary signal into an electrical signal;
means for amplifying a signal amplitude of the electrical signal;
means for controlling a scan speed of the charged particle beam;
means for calculating a degradation function between a first electrical signal and a second electrical signal, the first electrical signal being acquired when the charged particle beam is scanned at a first speed, which results in the first electrical signal being subjected to a band limitation of an electrical signal path, and the second electrical signal being acquired when the charged particle beam is scanned at a second speed, which does not result in the second electrical signal being subjected to the band limitation of the electrical signal path;
means for calculating an inverse function of the degradation function as a correction filter;
means for generating the second electrical signal by applying the correction filter to the first electrical signal; and
means for updating the correction filter, wherein
the degradation function is calculated using the first electrical signal and the second electrical signal by quantifying the degradation of the first electrical signal as compared to the second electrical signal.
2. The charged particle beam device according to claim 1 , wherein the degradation function is an inverse Fourier transform of a function obtained by dividing a Fourier transform of the second electrical signal by the Fourier transform of the first electrical signal.
3. The charged particle beam device according to claim 1 , further comprising:
a memory storing multiple correction filters for use with different scanning conditions, wherein
the stored correction filters are updated in a batch by a function of the means for updating the correction filter.
4. The charged particle beam device according to claim 1 , wherein the means for updating the correction filter has a function of selectively updating one or more given selected correction filters.
5. The charged particle beam device according to claim 1 , wherein the means for updating the correction filter has a function of updating a correction filter being used on a background of sample observation.
6. The charged particle beam device according to claim 1 , further comprising means for, in sample observation, informing an operator of information that identifies a correction filter being used.
7. The charged particle beam device according to claim 1 , further comprising means for managing the correction filter using a table.
8. The charged particle beam device according to claim 1 , further comprising means for transferring or inputting the correction filter to a storage medium externally connected via an information processing device.
9. The charged particle beam device according to claim 2 , further comprising means for displaying an image, to which the correction filter is not yet applied, and an image, to which the correction filter is applied, on the display screen in accordance with an operation input.
10. The charged particle beam device according to claim 2 , further comprising:
a memory storing multiple correction filters for use with different scanning conditions, wherein
the stored correction filters are updated in a batch by a function of the means for updating the correction filter therein the means for updating the correction filter has a function of updating all correction filters in a batch.
11. The charged particle beam device according to claim 2 , wherein the means for updating the correction filter has a function of selectively updating one or more given selected correction filters.
12. The charged particle beam device according to claim 2 , wherein the means for updating the correction filter has a function of updating a correction filter being used on a background of sample observation.
13. The charged particle beam device according to claim 2 , further comprising means for, in sample observation, informing an operator of information that identifies a correction filter being used.
14. The charged particle beam device according to claim 2 , further comprising means for managing the correction filter using a table.
15. The charged particle beam device according to claim 2 , further comprising means for transferring or inputting the correction filter to a storage medium externally connected via an information processing device.
16. A method for correcting a detected signal of a charged particle beam device, comprising the processes of:
generating a charged particle beam from a charged particle beam source;
detecting a secondary signal generated from a sample upon irradiation of the sample with the charged particle beam;
converting the secondary signal into an electrical signal;
amplifying a signal amplitude of the electrical signal;
controlling a scan speed of the charged particle beam;
calculating a degradation function between a first electrical signal and a second electrical signal, the first electrical signal being acquired when the charged particle beam is scanned at a first speed, which results in the first electrical signal being subjected to a band limitation of an electrical signal path, and
the second electrical signal being acquired when the charged particle beam is scanned at a second speed, which does not result in the second electrical signal being subjected to the band limitation of the electrical signal path;
calculating an inverse function of the degradation function as a correction filter;
generating a reconstructed the second electrical signal by applying the correction filter to the first electrical signal; and
updating the correction filter, wherein
the degradation function is calculated using the first electrical signal and the second electrical signal by quantifying the degradation of the first electrical signal as compared to the second electrical signal.