Multi-beam charged particle microscope design with improved detection system for secondary electron imaging over a large range of landing energies of primary electrons

A multi-beam charged particle beam system configured to generate a plurality of primary charged-particle beamlets, the multi-beam charged particle beam system comprising:

• an object irradiation unit configured to generate a plurality of focus points of the plurality of primary charged-particle beamlets in an object plane of the multi-beam charged particle beam system;
• a sample stage configured to arrange a surface of an object in the object plane;
• a voltage supply unit configured to provide a voltage to the object to set a landing energy of primary charged particles of the plurality of primary charged-particle beamlets within a range between 100 eV or less and 2 keV or more;
• a detection unit configured to provide at least a part of a secondary electron imaging system configured to image a plurality of secondary electron beamlets generated at the surface of the object at the plurality of focus points, the secondary electron beamlets travelling along a secondary electron beam path onto a detector of the detection unit;
• a beam divider configured to separate the plurality of primary charged-particle beamlets from the plurality of secondary electron beamlets;
• a first compensator;
• and
• a second compensator,
• wherein the first and second compensators are configured to jointly compensate an aberration of an electron-optical element of the secondary electron imaging system within a range of kinetic energies of secondary electrons of the plurality of secondary electron beamlets that is the same as the range of the landing energy of the primary charged particles.

A method of operating a multi-beam charged particle beam system, the method comprising:

• positioning an inspection site on a wafer in a field of view of the multi-beam charged particle beam system;
• adjusting a selected landing energy of primary electrons within a range of landing energies by providing a sample voltage to the wafer;
• determining a sensitivity matrix of a compensator for the selected landing energy LES;
• determining an aberration of a secondary electron imaging system at the selected landing energy;
• determining an actuation of the compensator at the selected landing energy to compensate the aberration;
• applying the actuation of first compensator;
• and
• inspecting the wafer.