Particle-optical systems and arrangements and particle-optical components for such systems and arrangements

A multi-electron-beamlet inspection system, comprising:

• a stage for mounting an object to be inspected;
• an electron source arrangement for generating an array of primary electron beamlets;
• an objective lens for focusing each of the primary electron beamlets on the object, wherein an array of secondary electron beamlets is generated by the primary electron beamlets, the secondary electron beamlets traversing the objective lens;
• a beam splitter for separating a secondary electron beam path of the secondary electron beamlets from a primary electron beam path of the primary electron beamlets;
• a detector arrangement for producing an array of signals corresponding to the array of secondary electron beamlets;
• wherein the beam splitter includes a magnet arrangement having:
• a first magnetic field region traversed by the primary electron beam path and the secondary electron beam path for separating the primary electron beam path and the secondary electron beam path from each other,
• a second magnetic field region arranged in the primary electron beam path upstream of the first magnetic field region, wherein the second magnetic field region is not traversed by the secondary electron beam path, and wherein the first and second magnetic field regions deflect the primary electron beam path in substantially opposite directions,
• a third magnetic field region arranged in the secondary electron beam path downstream of the first magnetic field region, wherein the third magnetic field region is not traversed by the first electron beam path, and wherein the first and third magnetic field regions deflect the secondary electron beam path in a substantially same direction.

A method of multi-electron-beamlet inspection of a substrate, the method comprising:

• generating an array of primary electron beamlets;
• focusing each primary electron beamlet on the substrate such that an array of secondary electron beamlets emanating from the substrate is generated;
• detecting intensities of the secondary electron beamlets;
• and
• separating a secondary electron beam path of the secondary electron beamlets from a primary electron beam path of the primary electron beamlets using a beam splitter, the beam splitter including a magnet arrangement having:
• a first magnetic field region traversed by the primary electron beam path and the secondary electron beam path for separating the primary electron beam path and the secondary electron beam path from each other,
• a second magnetic field region arranged in the primary electron beam path upstream of the first magnetic field region, wherein the second magnetic field region is not traversed by the secondary electron beam path, and wherein the first and second magnetic field regions deflect the primary electron beam path in substantially opposite directions, and
• a third magnetic field region arranged in the secondary electron beam path downstream of the first magnetic field region, wherein the third magnetic field region is not traversed by the first electron beam path, and wherein the first and third magnetic field regions deflect the secondary electron beam path in a substantially same direction.