METHOD FOR DETERMINING A RECONSTRUCTED IMAGE USING A PARTICLE-OPTICAL APPARATUS

• US 20120273676A1
• Filed: 04/25/2012
• Published: 11/01/2012
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: FEI Company (Thermo Fisher Scientific Incorporated)
• Original Assignee: FEI Company (Thermo Fisher Scientific Incorporated)
• Inventors: Kuijper, Maarten
• Granted Patent: US 8,624,183 B2
• Time in Patent Office: Days
• US Class Current: 250/307
• CPC Class Codes: G06T 2207/10061 from scanning electron microscope
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: H01J 37/222 Image processing arrangements associated with the tube image data processing or generation, in general G06T
• CPC Class Codes: H01J 37/26 Electron or ion microscopes; Electron or ion diffraction tubes

Abstract

The invention relates to a method for determining a reconstructed image using a particle-optical apparatus. The particle-optical apparatus comprises a particle source for producing a beam of particles, an object plane on which an object to be imaged may be placed, a condenser system for illuminating the object plane with the beam of particles, a projection system for forming an image of the object plane by imaging particles transmitted through the object on an image plane, and a detector for detecting the image, the detector comprising a semiconductor sensor having an array of pixels for providing a plurality of pixel signals from respective pixels of the array in response to particles incident on the detector.

Claims

1. Method for determining a reconstructed image using a particle-optical apparatus, the particle-optical apparatus comprising:

a particle source for producing a beam of particles,

an object plane on which an object to be imaged may be placed,

a condenser system for illuminating the object plane with the beam of particles,

a projection system for forming an image of the object plane by imaging particles transmitted through the object on an image plane, and

a detector for detecting the image, the detector comprising a semiconductor sensor having an array of pixels for providing a plurality of pixel signals from respective pixels of the array in response to particles incident on the detector,

the method comprising;

receiving the plurality of pixel signals, and

determining a reconstructed image from using Viterbi Detection on the plurality of pixel signals,

the Viterbi Detection using a plurality of different states corresponding to a plurality of configurations of particles incident on the detector, and

at least two states of the plurality of different states corresponding to a same, non-zero multiplicity of incident particles on a single pixel of the plurality of pixel signals.

2. Method according to claim 1, wherein the different states are modelled using a different multiplicity of particles.

3. Method according to claim 1, wherein the different states are modelled using different deposited energies of the particle(s).

4. Method according to claim 1, wherein the different states are modelled using different point spread functions in modelling deposited energies of the particle(s).

5. Method according to claim 1, wherein the different states are used in different iterations of the Viterbi Detection.

6. Method according to claim 1, wherein the array of pixels is a one-dimensional array.

7. Method according to claim 1, wherein the array of pixels is a two-dimensional array and the Viterbi Detection is applied to sequences of pixel signals per row of pixels of the two-dimensional array.

8. Method according to claim 1, wherein the array of pixels is a two-dimensional array and the Viterbi Detection is applied to sequences of pixel signals per column of pixels of the two-dimensional array.

9. Method according to claim 7, wherein the states of the Viterbi Detection correspond to predetermined two-dimensional configurations of particles incident on the detector.

10. Method according to claim 1, further comprising, after having detected one or more incident particles on a pixel, removing a contribution from the detected one or more incident particles from the plurality of pixel signals.

11. Method according to claim 1, wherein the image detected by the detector comprises a dose in a range of 0.0001-0.5, preferably 0.001-0.3, even more preferably 0.01-0.1 particle per pixel.

12. Method according to claim 1, the method comprising:

receiving a first plurality of pixel signals from respective pixels of the array in response to particles incident on the detector upon detecting a first image of the object,

determining a first reconstructed image from using the Viterbi Detection on the first plurality of pixel signals,

receiving a second plurality of pixel signals from the respective pixels of the array in response to particles incident on the detector upon detecting a second image of the object,

determining a second reconstructed image from using the Viterbi Detection on the second plurality of pixel signals, and

combining the first reconstructed image and the second reconstructed image to form the reconstructed image.

13. Method according to claim 1, further comprising:

producing a beam of particles,

placing an object to be imaged on an object plane,

illuminating the object plane with the beam of particles,

forming an image of the object plane by imaging particles transmitted through the object on an image plane, and

detecting the image with the detector comprising the semiconductor sensor and providing a plurality of pixel signals from the respective pixels of the array in response to the particles incident on the detector.

14. Particle-optical apparatus comprising:

a particle source for producing a beam of particles,

an object plane on which an object to be imaged may be placed,

a condenser system for illuminating the object plane with the beam of particles,

a projection system for forming an image of the object plane by imaging particles transmitted through the object on an image plane,

a detector for detecting the image, the detector comprising a semiconductor sensor having an array of pixels for providing a plurality of pixel signals from respective pixels of the array in response to particles incident on the detector, and

a signal processor arranged to perform the method of claim 1.

15. A computer program product comprising instructions for causing a processor system to perform the method according to claim 1.

16. A method according to claim 8, wherein the states of the Viterbi Detection correspond to predetermined two-dimensional configurations of particles incident on the detector.

17. A method for determining a reconstructed image using a particle-optical apparatus, comprising:

providing a particle optical apparatus having a detector for detecting an image, the detector providing a plurality of pixel signals from respective pixels in response to particles incident on the detector.

receiving the plurality of pixel signals; and

determining a reconstructed image from using Viterbi Detection on the plurality of pixel signals, the Viterbi Detection using a plurality of different states corresponding to a plurality of configurations of particles incident on the detector, and at least two states of the plurality of different states corresponding to a same, non-zero multiplicity of incident particles on a single pixel of the plurality of pixel signals.

18. The method of claim 17, wherein the different states are modelled using a different multiplicity of particles.

19. The method of claim 17, wherein the different states are modelled using different deposited energies of the particle(s).

20. The method of claim 17, wherein the different states are modelled using different point spread functions in modelling deposited energies of the particle(s).