Distortion optimized multi-beam scanning system

A multi-beam charged particle microscope, comprising:

• a charged-particle multi-beamlet generator configured to generate a plurality of primary charged particle beamlets;
• an object irradiation unit configured to illuminate an image patch on a surface of an object in an object plane by the plurality of primary charged particle beamlets to generate a plurality of secondary electron beamlets (9) emitting from the surface;
• a detection unit comprising a projection system and an image sensor, the projection lens configured to image the plurality of secondary electron beamlets onto the image sensor to acquire a digital image of the image patch;
• a collective multi-beam raster scanner;
• a scanning distortion compensator array disposed in a propagation direction of the plurality of primary charged particles upstream of the collective multi-beam raster scanner, the scanning distortion compensator array comprising a plurality of apertures, each aperture configured to transmit a corresponding primary charged particle beamlet of the plurality of primary charged particle beamlets, the plurality of apertures comprising a plurality of first deflection elements configured to individually deflect each corresponding primary charged particle beamlet in a first direction and a plurality of second deflection elements configured to individually deflect each corresponding primary charged particle beamlet in a second or direction perpendicular to the first direction, each deflection element disposed in a circumference of each aperture;
• control unit configured to provide a first scanning voltage difference to the collective multi-beam raster scanner to scanningly deflect the plurality of primary charged particle beamlets in the first direction,
• wherein the scanning distortion compensator array further comprises a scanning array control unit comprising a first static voltage conversion array configured to provide a plurality of first correction voltage differences to the plurality of first deflection elements and a second static voltage conversion array configured to provide a plurality of second correction voltage differences to the plurality of second deflection elements to compensate a scanning induced aberration during the scanning deflection of the plurality of primary charged particle beamlets in the first direction.