Method of calibrating a scanning transmission charged-particle microscope

1. A method of calibrating a Scanning Transmission Charged-Particle Microscope comprising:

a specimen holder, for holding a specimen;

a source, for producing a beam of charged particles;

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

an imaging system, for directing charged particles that traverse the specimen onto a detector;

scanning means, for causing said beam to undergo scanning motion relative to a surface of the specimen,

which microscope can be operated in:

a non-scanning mode, whereby said beam is relatively broad and said detector forms an image without invocation of said scanning means; or

a scanning mode, whereby said beam is relatively narrow and said detector accumulates an image as a function of scan position of said beam,

said calibration method comprising:

providing a calibration specimen on said specimen holder;

in non-scanning mode, using said detector to form a calibration image of the calibration specimen, using a given configuration of said imaging system;

utilizing a known dimension of said calibration specimen and comparing it to a corresponding dimension in said calibration image to calibrate a characteristic dimension of a field of view of said detector;

in scanning mode, recording a beam pattern of said beam in the calibrated field of view of said detector, and examining the recorded beam pattern to derive a geometric aspect thereof.

2. A method according to claim 1 , wherein said characteristic dimension of the field of view of the detector is selected from the group comprising a pixel size, a side length, a diagonal length, a diameter, a dimension of a field marker, and combinations hereof.

3. A method according to claim 1 , wherein:

said beam pattern comprises a linear tract in a given direction;

said geometric aspect is a length of said linear tract.

4. A method according to any of claim 1 , wherein:

said beam pattern comprises a first linear tract in a first direction and a second linear tract in a second direction;

said geometric aspect is chosen from the group comprising:

a length ratio of said first and second linear tracts;

an angle between said first and second linear tracts.

5. A method according to claim 1 , wherein:

said beam pattern comprises an array of test figures, disposed at different coordinate positions in said calibrated field of view;

said geometric aspect is distortion, measured as a function of position in said field of view.

6. A method according to claim 5 , wherein said distortion is selected from the group comprising shift, rotation, scaling, shear, skew, and combinations hereof.

7. A method according to claim 1 , wherein said calibration specimen comprises a crystal, and said known dimension is a lattice length of the crystal.

8. A charged-particle microscope, comprising:

a specimen holder, for holding a specimen;

a source, for producing a beam of charged particles;

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

an imaging system, for directing charged particles that traverse the specimen onto a detector;

scanning means, for causing said beam to undergo scanning motion relative to a surface of the specimen,

a controller, for executing control commands,

which microscope can be operated in:

a non-scanning mode, whereby said beam is relatively broad and said detector forms an image without invocation of said scanning means; or

a scanning mode, whereby said beam is relatively narrow and said detector accumulates an image as a function of scan position of said beam; and

in which the controller is programmed to execute the following steps:

in non-scanning mode, using said detector to form a calibration image of a calibration specimen, using a given configuration of said imaging system;

utilizing a known dimension of said calibration specimen and comparing it to a corresponding dimension in said calibration image to calibrate a characteristic dimension of a field of view of said detector;

in scanning mode, recording a beam pattern of said beam in the calibrated field of view of said detector, and examining the recorded beam pattern to derive a geometric aspect thereof.

9. The charged particle microscope of claim 8 , wherein the beam pattern comprises an array of test figures, disposed at different coordinate positions in said calibrated field of view; and

the geometric aspect is distortion, measured as a function of position in said field of view.

10. The charged particle microscope of claim 9 , wherein said distortion is selected from the group comprising shift, rotation, scaling, shear, skew, and combinations hereof.

11. The charged particle microscope of claim 8 , wherein said calibration specimen comprises a crystal, and said known dimension is a lattice length of the crystal.

12. The charged particle microscope of claim 8 , wherein said beam pattern comprises a linear tract in a given direction; and

said geometric aspect is a length of said linear tract.

13. The charged particle microscope of claim 8 , wherein said beam pattern comprises a first linear tract in a first direction and a second linear tract in a second direction, said geometric aspect is chosen from the group comprising:

a length ratio of said first and second linear tracts; and

an angle between said first and second linear tracts.

14. The charged particle microscope of claim 8 , wherein said characteristic dimension of the field of view of the detector is selected from the group comprising a pixel size, a side length, a diagonal length, a diameter, a dimension of a field marker, and combinations hereof.