Multi-beam charged particle source with alignment means

A method for generating a plurality of charged particle beamlets, comprising the steps of:

• generating a diverging charged particle beam using a charged particle source,
• splitting said charged particle beam in an array of charged particle beamlets using a beam splitter,
• deflecting substantially each charged particle beamlet of said array of charged particle beamlets using a deflector array comprising an array of deflectors comprising one deflector for each charged particle beamlet, wherein the deflector array is configured to at least substantially collimate the array of diverging charged particle beamlets, and
• generating electric and/or magnetic fields at least in an area between the charged particle source and the deflector array using a beam manipulation device for aligning the array of charged particle beamlet with respect to the array of deflectors of said deflector array,
• wherein apparatus comprises a central axis, wherein the charged particle source, a center of the beam splitter and a center of the deflector array are arranged on the central axis, and wherein the beam manipulation device generates:
• an electric field substantially perpendicular to the central axis, and/or
• a magnetic field substantially perpendicular to the central axis.

An apparatus for generating a plurality of charged particle beamlets, comprising:

• a charged particle source for generating a diverging charged particle beam,
• a beam splitter for splitting said charged particle beam in an array of charged particle beamlets,
• a deflector array comprising an array of deflectors comprising one deflector for each charged particle beamlet of said array of charged particle beamlets, wherein the deflector array is configured for at least substantially collimating the array of diverging charged particle beamlets, and
• a beam manipulation device configured for generating electric and/or magnetic fields at least in an area between the charged particle source and the deflector array, wherein the electric and/or magnetic fields are configured for optimizing an alignment of the charged particle beamlets on the deflector array,
• wherein apparatus comprises a central axis, wherein the charged particle source, a center of the beam splitter and a center of the deflector array are arranged on the central axis, and wherein the beam manipulation device comprises:
• a set of at least two coils which are arranged on opposite sides of the central axis and having a common coil center axis, wherein the common coil center axis is arranged in a plane which is substantially perpendicular to the central axis, and/or
• a set of at least two electrodes arranged on opposite sides of the central axis and on a common electrode axis, wherein the common electrode axis is arranged in a plane which is substantially perpendicular to the central axis.