Method of examining a sample in a charged-particle microscope

1. A method of examining a sample in a charged-particle microscope of a scanning transmission type, comprising:

providing a beam of charged particles that is directed from a source through an illuminator so as to irradiate the sample;

providing a detector for detecting a flux of charged particles traversing the sample;

causing said beam to scan across a surface of the sample, and recording an output of the detector as a function of scan position, resulting in accumulation of a charged-particle image of the sample,

including:

embodying the detector to comprise a plurality of detection segments;

combining signals from different segments of the detector so as to produce a vector output from the detector at each scan position, and compiling this data to yield a vector field;

mathematically processing said vector field by subjecting it to a two-dimensional integration operation, thereby producing an integrated vector field image.

2. A method according to claim 1 , wherein:

said detector is embodied to comprise four quadrants;

said vector output is produced by calculating difference signals between complementary pairs of quadrants.

3. A method according claim 2 , wherein said integrated vector field image is post-processed by subjecting it to at least one operation selected from the group comprising:

filtering;

opening Angle Correction;

deconvolution correction,

and combinations hereof.

4. A method according to claim 2 , wherein the integrated vector field image is further manipulated by subjecting it to a Laplacian operation.

5. A method according to claim 2 , wherein the integrated vector field image is further manipulated by subjecting it to a single differentiation operation.

6. A method according to claim 2 , wherein said mathematical processing of vector field {tilde over (E)} comprises finding an estimate {circumflex over (φ)} of a potential φ as a fitting problem involving functional minimization of an objective function J defined as:

J (φ)=∫∫∥(−∇φ)− {tilde over (E)}∥ 2 dxdy=∫∫∥∇φ+{tilde over (E)}∥ 2 dxdy

for Cartesian coordinates (x, y) along a scan path of said beam on the sample.

7. A method according to claim 1 , wherein:

said detector is embodied as a pixelated detector comprising an array of pixels;

said vector output is produced using a procedure comprising the following steps:

comparing pixel values to determine a location for a barycenter of said flux on the detector;

expressing a coordinate position of said barycenter on the detector.

8. A method according to claim 7 , wherein the charged particles are electrons.

9. A method according claim 7 , wherein said integrated vector field image is post-processed by subjecting it to at least one operation selected from the group comprising:

filtering;

opening Angle Correction;

deconvolution correction,

and combinations hereof.

10. A method according to claim 7 , wherein the integrated vector field image is further manipulated by subjecting it to a Laplacian operation.

11. A method according to claim 7 , wherein the integrated vector field image is further manipulated by subjecting it to a single differentiation operation.

12. A method according to claim 7 , wherein said mathematical processing of vector field {tilde over (E)} comprises finding an estimate {circumflex over (φ)} of a potential φ as a fitting problem involving functional minimization of an objective function J defined as:

J (φ)=∫∫∥(−∇φ)− {tilde over (E)}∥ 2 dxdy=∫∫∥∇φ+{tilde over (E)}∥ 2 dxdy

for Cartesian coordinates (x, y) along a scan path of said beam on the sample.

13. A method according to claim 1 , wherein the employed detector is a Position-Sensitive Detector.

14. A method according to claim 1 , wherein said integrated vector field image is post-processed by subjecting it to at least one operation selected from the group comprising:

filtering;

opening Angle Correction;

deconvolution correction,

and combinations hereof.

15. A method according to claim 1 , wherein the integrated vector field image is further manipulated by subjecting it to a Laplacian operation.

16. A method according to claim 1 , wherein the integrated vector field image is further manipulated by subjecting it to a single differentiation operation.

17. A method according to claim 1 , wherein said mathematical processing of vector field {tilde over (E)} comprises finding an estimate {circumflex over (φ)} of a potential φ as a fitting problem involving functional minimization of an objective function J defined as:

J (φ)=∫∫∥(−∇φ)− {tilde over (E)}∥ 2 dxdy=∫∫∥∇φ+{tilde over (E)}∥ 2 dxdy

for Cartesian coordinates (x, y) along a scan path of said beam on the sample.

18. A method according to claim 17 , wherein said functional minimization is achieved with the aid of at least one technique selected from the group comprising:

a Poisson solver technique;

a Basis Function reconstruction;

residual minimization using an Lp norm-based objective function;

residual minimization using an M-estimator;

anisotropic weighting;

application of a Diffusion tensor;

application of a regularization function,

and combinations hereof.

19. A method according to claim 1 , wherein the charged particles are electrons.

20. A charged-particle microscope of a scanning transmission type, comprising:

a sample holder, for holding a sample;

a source, for producing a beam of charged particles;

an illuminator, for directing said beam so as to irradiate said sample;

a detector, for detecting a flux of charged particles traversing the sample in response to said irradiation;

scanning means, for causing said beam to make a scanning motion relative to a surface of the sample;

a controller, for recording an output of said detector as a function of scan position, resulting in accumulation of a charged-particle image of the sample,

characterized in that:

said detector comprises a plurality of detection segments;

said controller is embodied to perform the following additional actions:

combine signals from different segments of the detector so as to produce a vector output from the detector at each scan position, and compile this data to yield a vector field;

mathematically process said vector field by subjecting it to a two-dimensional integration operation, thereby producing an integrated vector field image.