Systems and methods for compensating dispersion of a beam separator in a single-beam or multi-beam apparatus

A charged particle beam apparatus comprising:

• a source for generating a primary charged particle beam;
• a first dispersion device downstream from the source;
• a beam separator downstream the first dispersion device;
• an objective lens downstream the beam separator;
• a sample stage for supporting a sample;
• and
• a charged particle detector,
• wherein the first dispersion device comprises a combination of an electrostatic deflector and a magnetic deflector configured for inducing a plurality of first beam dispersions to a plurality of beamlets of the primary charged particle beam, and
• wherein the plurality of first beam dispersions are set to minimize impacts of a plurality of second beam dispersions of the plurality of beamlets of the charged particle beam caused by the beam separator.

A method for controlling dispersion in a charged particle beam system with a dispersion device, the method comprising:

• placing the dispersion device upstream of a beam separator;
• and
• generating a plurality of first beam dispersions to a plurality of beamlets of a charged particle beam by the dispersion device;
• wherein the dispersion device comprises a combination of an electrostatic deflector and a magnetic deflector configured for inducing the plurality of first beam dispersions, and
• wherein the plurality of first beam dispersions are set to cancel impacts of a plurality of second beam dispersions of the plurality of beamlets of the charged particle beam caused by the beam separator.