A new design concept of scanning electron microscope with charged particle source

A non-transitory computer readable medium storing a set of instructions that is executable by one or more processors of a charged particle beam apparatus to cause the charged particle beam apparatus to perform a method of inspecting a sample, the method comprising:

• causing a charged particle source to emit a primary beam of charged particles;
• forming a first set of charged particle beamlets using a first set of apertures on an aperture substrate by passing a portion of charged particles of the primary beam of charged particles through the first set of apertures, wherein secondary charged particles emitted in response to the first set of charged particle beamlets impacting the sample are detected by one or more first detectors;
• focusing the first set of charged particle beamlets using an objective lens to a focal point substantially at the sample;
• forming a second charged particle beamlet using a second aperture on the aperture substrate by passing a portion of charged particles of the primary beam of charged particles through the second aperture, wherein the second charged particle beamlet is active at a same time as the first set of charged particle beamlets and is directed to an auxiliary detector without interacting with the sample, and the first set of charged particle beamlets and the second charged particle beamlet have no beamlet in common;
• and
• generating an image based on detection data from the one or more first detectors and based on detection data from the auxiliary detector.

An apparatus for compensating for variations in charged particle beam current in generation of an image of a sample, comprising:

• a charged particle source configured to emit a primary beam of charged particles;
• a monitoring component including circuitry configured to monitor a characteristic of the charged particle source and to determine whether the characteristic of the charged particle source has deviated from a threshold value, wherein the characteristic of the charged particle source affects an emission of the primary beam of charged particles;
• an image detector configured to measure a characteristic for a secondary charged particle emitted from the sample via scanning the primary beam of charged particles over the sample;
• and
• an image processor including circuitry configured to determine a characteristic of the charged particle source based on the measured characteristic of the secondary charged particle to compensate for the deviated characteristic of the charged particle source, if the characteristic of the charged particle source has deviated from the threshold value and to generate a compensated image of the sample based on the determined characteristic of the charged particle source.