Multi-beam charged particle imaging system with improved imaging of secondary electron beamlets on a detector

A method, comprising, comprising:

• using a multi-beam charged particle imaging system to generate a plurality of primary charged particle beamlets in a first raster configuration;
• irradiating a surface of an object with the plurality of primary charged particle beamlets to generate a plurality of secondary charged particle beamlets in a second raster configuration;
• forming secondary electron focus spots of the plurality of secondary charged particle beamlets on a detector in a third raster configuration;
• and
• operating the multi-beam charged particle imaging system to:
• i) obtain an image of a surface segment of the object;
• or ii) determine the third raster configuration.

A multi-beam charged particle imaging system, comprising:

• a multi-beam generator configured to generate a plurality of primary charged particle beamlets in a first raster configuration;
• a primary electron optical system configured to generate a plurality of focus spots of the plurality of primary charged particle beamlets on a surface of an object, the primary electron optical system comprising a first deflection scanner;
• a beam divider;
• a detector comprising a plurality of sets of detection elements in a fourth raster configuration;
• a secondary electron optical system configured to generate a plurality of focus spots of secondary electron beamlets in a third raster configuration on the detector, the plurality of secondary charged particle beamlets originating from the focus spots of the plurality of primary charged particle beamlets, the secondary electron optical system comprising a second deflection scanner;
• and
• a controller configured to switch the first and second deflection scanners between an inspection mode of operation and an alignment mode of operation,
• wherein:
• during the inspection mode of operation, operation of the first and second deflection scanner is synchronized and adjusted so that the plurality of focus points of secondary particle beamlets is kept on fixed positions at the detector so that each secondary beamlet is assigned to and collected by a set of detection elements;
• and
• during the alignment mode of operation, operation of the first deflection scanner and/or the second deflection scanners to laterally sweep the plurality of secondary particle beamlets over the detector.

A method, comprising:

• using a multi-beam charged particle beam system to generate a plurality of primary charged particle beamlets in a first raster configuration;
• irradiating a surface of an object with the plurality of primary charged particle beamlets to generate a plurality of secondary charged particle beamlets;
• forming secondary electron focus spots of the plurality of secondary charged particle beamlets on a detector in a third raster configuration;
• scanning the secondary electron focus spots over the detector and generating a plurality of scanning intensity signals;
• determining, from the plurality of scanning intensity signals, at least one member selected from the group consisting of a first scale of the third raster configuration, a first lateral position of the third raster configuration, and a first rotation of the third raster configuration;
• using the monitoring system to determine at least one member selected from the group consisting of a second scale of the focus spots of the plurality of secondary charged particle beamlets, a second lateral position of the focus spots of the plurality of secondary charged particle beamlets, and a second rotation of the focus spots of the plurality of secondary charged particle beamlets;
• and
• matching at least one member selected from the group consisting of:
• i) the second scale to the first scale;
• ii) the second lateral position to the first lateral position;
• and ii) the second rotation to the first rotation.