Charged particle beam energy width reduction apparatus, method of operating thereof, and charged particle beam device

A charged particle beam device having an optical axis, comprising:

• a charged particle beam source configured to generated a primary charged particle beam;
• a charged particle beam energy width reduction apparatus, comprising:
• a first round lens configured to decelerate a primary charged particle beam and to focus the primary charged particle beam in a focusing plane;
• a charged particle deflector assembly configured to generate dispersion in the focusing plane, the charged particle deflector assembly comprising:
• a first electrostatic charged particle deflector arranged on the optical axis and comprising two flat conducting surfaces;
• and
• a second electrostatic charged particle deflector comprising two flat conducting surfaces;
• the charged particle beam energy width reduction apparatus further comprising:
• a beam limiting opening in an aperture body positioned in the focusing plane and off-axis with respect to the optical axis;
• the charged particle beam device further comprising:
• an objective lens configured to focus the primary charged particle beam.

A method of operating a charged particle beam device having a charged particle beam energy width reduction apparatus, comprising:

• generating a primary charged particle beam;
• focusing the primary charged particle beam in a focusing plane with a first round lens and decelerating the primary charged particle beam with the first round lens;
• generating dispersion in the focusing plane with a charged particle deflector assembly comprising:
• a first electrostatic charged particle deflector arranged on an optical axis and comprising two flat conducting surfaces;
• and
• a second electrostatic charged particle deflector comprising two flat conducting surfaces;
• the method further comprising:
• reducing an energy width of the primary charged particle beam with a beam limiting opening in an aperture body positioned in the focusing plane and off-axis with respect to an optical axis.