Computational scanning microscopy with improved resolution

1. A method of accumulating an image of a specimen using a scanning-type microscope, comprising the following steps:

directing a beam of radiation from a source through an illuminator so as to irradiate a surface S of the specimen;

using a detector to detect a flux of radiation emanating from the specimen in response to said irradiation;

causing said beam to follow a scan path relative to said surface;

for each of a set of sample points in said scan path, recording an output Dn of the detector as a function of a value Pn of a selected measurement parameter P, thus compiling a measurement set M={(Dn, Pn)}, where n is a member of an integer sequence;

using computer processing apparatus to automatically deconvolve the measurement set M and spatially resolve it into a result set R representing depth-resolved imagery of the specimen,

wherein, considered at a given point pi within the specimen, the method comprises the following steps:

in a first probing session, employing a first beam configuration B1 to irradiate the point pi with an associated first Point Spread Function F1, whereby said beam configuration is different to said measurement parameter;

in at least a second probing session, employing a second beam configuration B2 to irradiate the point pi with an associated second Point Spread Function F2, whereby F2 overlaps partially with F1 in a common overlap zone Oi in which point pi is located;

using an Independent Component Analysis algorithm in said computer processing apparatus to perform spatial resolution in said overlap zone Oi.

2. The method according to claim 1 , wherein

said surface is defined to extend parallel to an XY-plane of a Cartesian coordinate system XYZ;

said beam configuration is chosen to be a Z-position of a point of entry of the beam into the specimen;

between said first and second probing sessions, a physical slicing procedure is used to remove a layer of material of thickness L from an initial surface S1, thereby exposing a new surface S2;

point Spread Functions F2 and F1 are displaced relative to one another in said Z-direction by an amount L.

3. The method according to claim 1 , wherein:

said beam configuration is chosen to be an angle of the beam relative to the surface S;

between said first and second probing sessions, said angle of the beam is adjusted;

point Spread Functions F2 and F1 are angled relative to one another.

4. The method according to claim 1 , wherein:

said beam configuration is selected to be a species of particle in said beam;

point Spread Functions F2 and F1 are mutually different as regards to at least one of size and shape.

5. The method according to claim 1 , wherein said measurement parameter is selected from the group comprising:

an average landing energy of particles in said beam;

an average current of charged particles in said beam;

an emission angle of particles in said flux;

an emission energy of particles in said flux,

and combinations hereof.

6. The method according to claim 1 , wherein said flux of radiation emanating from the specimen comprises at least one species selected from the group comprising backscatter electrons, secondary electrons, X-rays, infrared light, visible light, ultraviolet light, and combinations hereof.

7. The method according to claim 1 , wherein said deconvolution and spatial resolution of the measurement set M are performed by minimizing a statistical divergence between a detection model and the measurement set M, assumed subject to at least one of Poisson noise and Gaussian noise, whilst applying constraints to said model.

8. A scanning-type microscope comprising:

a specimen holder, for holding a specimen;

a source, for producing a beam of radiation;

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

a detector, for detecting a flux of radiation emanating from the specimen in response to said irradiation;

scanning means, for causing said beam to traverse a scan path relative to a surface of the specimen;

a controller, for:

recording an output Dn of the detector as a function of a value Pn of a selected measurement parameter P, for each of a set of sample points in said scan path, thus compiling a measurement set M={(Dn, Pn)}, where n is a member of an integer sequence;

automatically deconvolving the measurement set M and spatially resolving it into a result set R representing depth-resolved imagery of the specimen,

wherein, in respect of a given point pi within the specimen, said controller can be invoked to execute the following steps:

in a first probing session, employ a first beam configuration B1 to irradiate the point pi with an associated first Point Spread Function F1, whereby said beam configuration is different to said measurement parameter;

in at least a second probing session, employ a second beam configuration B2 to irradiate the point pi with an associated second Point Spread Function F2, whereby F2 overlaps partially with F1 in a common overlap zone Oi in which point pi is located;

use an Independent Component Analysis algorithm to perform spatial resolution in said overlap zone Oi.

9. The scanning-type microscope according to claim 8 , wherein

said beam configuration is chosen to be a Z-position of a point of entry of the beam into the specimen;

between said first and second probing sessions, a physical slicing procedure is used to remove a layer of material of thickness L from an initial surface S1, thereby exposing a new surface S2;

point Spread Functions F2 and F1 are displaced relative to one another in said Z-direction by an amount L.

10. The scanning-type microscope according to claim 8 , wherein:

said beam configuration is chosen to be an angle of the beam relative to a surface S of the specimen;

between said first and second probing sessions, said angle of the beam is adjusted;

point Spread Functions F2 and F1 are angled relative to one another.

11. The scanning-type microscope according to claim 8 , wherein:

said beam configuration is selected to be a species of particle in said beam;

point Spread Functions F2 and F1 are mutually different as regards to at least one of size and shape.

12. The scanning-type microscope according to claim 8 , wherein said measurement parameter is selected from the group comprising:

an average landing energy of particles in said beam;

an average current of charged particles in said beam;

an emission angle of particles in said flux;

an emission energy of particles in said flux,

and combinations hereof.

13. The scanning-type microscope according to claim 8 , wherein said flux of radiation emanating from the specimen comprises at least one species selected from the group comprising backscatter electrons, secondary electrons, X-rays, infrared light, visible light, ultraviolet light, and combinations hereof.

14. The scanning-type microscope according to claim 8 , wherein said deconvolution and spatial resolution of the measurement set M are performed by minimizing a statistical divergence between a detection model and the measurement set M, assumed subject to at least one of Poisson noise and Gaussian noise, whilst applying constraints to said model.