Method for operating a multi-beam particle microscope with fast closed-loop beam current control, computer program product and multi-beam particle microscope

A multi-beam particle microscope, comprising the following:

• a beam generating system, comprising:
• a particle source;
• an extractor electrode;
• an anode, wherein the particle source, the extractor electrode and the anode are configured to produce a first charged particle beam;
• and
• an electrostatic control lens between the extractor electrode and the anode;
• a multi-beam generator comprising a multi-aperture array, the multi-beam generator being configured to produce a first field of a plurality of first individual charged particle beams from the first charged particle beam;
• a first beam current measuring mechanism at the multi-aperture array;
• a first particle optical unit having a first particle optical beam path, the first particle optical unit configured to direct the first individual particle beams to a sample such that the first individual particle beams strike the sample at incidence locations to form a second field;
• a detection system;
• a second particle optical unit having a second particle optical beam path, the second particle optical unit being configured to image onto the detection system second individual particle beams emanating from the incidence locations in the second field;
• a particle optical objective lens configured to have the first and the second individual particle beams pass therethrough;
• a beam switch which is in:
• the first particle optical beam path between the multi-beam generator and the objective lens;
• and the second particle optical beam path between the objective lens and the detection system;
• and
• a controller configured to control the beam generating system, the particle optical objective lens, the first particle optical unit, the second particle optical unit, and the detection system,
• wherein the controller being is configured to drive the electrostatic control lens based on a current measurement determined by first beam current measuring mechanism.

A multi-beam particle microscope, comprising:

• a beam generating system comprising a particle source, an extractor electrode and an anode and configured to produce a first charged particle beam, the beam generating system moreover comprising an electrostatic control lens arranged between the extractor electrode and the anode;
• a multi-beam generator having a multi-aperture array, the multi-beam generator being configured to produce a first field of a plurality of first individual charged particle beams from the first charged particle beam;
• a second beam current measuring mechanism, configured to measure an overall beam current of the individual particle beams;
• a first particle optical unit with a first particle optical beam path, configured to direct the generated first individual particle beams at a sample such that the first individual particle beams strike the sample at incidence locations, which form a second field;
• a detection system;
• a second particle optical unit with a second particle optical beam path, which is configured to image second individual particle beams, which emanate from the incidence locations in the second field, onto the detection system;
• a particle optical objective lens, through which both the first and the second individual particle beams pass;
• a beam switch, which is arranged in the first particle optical beam path between the multi-beam generator and the objective lens and which is arranged in the second particle optical beam path between the objective lens and the detection system;
• and
• a controller which is configured to control the beam generating system, the particle optical objective lens, the first particle optical unit, the second particle optical unit, and the detection system, and
• with the controller being configured for driving, in particular high-frequency driving, of the electrostatic control lens on the basis of the current measurement via the second beam current measuring mechanism.