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US 12,700,566 B2Granted
Objective lens array assembly, electron-optical system, electron-optical system array, method of focusing
AssigneeASML Netherlands B.V.
InventorMarco Jan-Jaco Wieland
Life of this patent
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Abstract
Objective lens array assemblies and associated methods are disclosed. In one arrangement, the objective lens array assembly focuses a multi-beam of sub-beams on a sample. Planar elements define a plurality of apertures aligned along sub-beam paths. An objective lens array projects the multi-beam towards a sample. Apertures of one or more of the planar elements compensate for off-axis aberrations in the multi-beam.
Claims18
An electron-optical apparatus for a charged-particle tool, the electron-optical apparatus comprising:
- a source configured to provide a beam of charged particles from which a multi-beam is derived;
- and
- an objective lens array assembly being configured to focus a multi-beam of sub-beams on a sample and comprising:
- planar elements defining a plurality of apertures aligned along sub-beam paths of the multi-beam and comprising:
- an objective lens array configured to project the multi-beam towards a sample;
- and
- a control lens array positioned up-beam of the objective lens array, the control lenses being configured to pre-focus the sub-beams,
- wherein apertures of one or more of the planar elements are configured to compensate for off-axis aberrations in the multi-beam, at least a subset of the apertures have a range of different aperture areas, the range of different aperture areas being selected to compensate for off-axis aberrations in the multi-beam, and
- wherein at least a subset of the apertures defined in the control lens array are provided at positions that are displaced relative to nominal positions, the displacements being selected to compensate for off-axis aberrations in the multi-beam.
6 more elements
An electron-optical apparatus for a charged-particle tool the electron-optical apparatus comprising:
- a source configured to provide a beam of charged particles from which a multi-beam is derived;
- a stage configured to support a sample, the stage comprises a support configured to support the sample;
- and
- an objective lens array assembly configured to focus a multi-beam of sub-beams on a sample and comprising:
- an objective lens array configured to project the multi-beam towards a sample;
- and
- a control lens array positioned up-beam of the objective lens array, the control lenses being configured to pre-focus the sub-beams,
- the objective lens array assembly comprising planar elements defining a plurality of apertures aligned along sub-beam paths of the multi-beam, wherein an array of the apertures defined in one or more of the planar elements is configured to compensate for off-axis aberrations in the multi-beam, at least a subset of the apertures have a range of different aperture areas, the range of different aperture areas being selected to compensate for off-axis aberrations in the multi-beam, and
- wherein at least a subset of the apertures defined in the control lens array are provided at positions that are displaced relative to nominal positions, the displacements being selected to compensate for off-axis aberrations in the multi-beam.
6 more elements
A method of focusing a multi-beam of charged particles towards a sample, comprising:
- providing an objective lens array assembly comprising planar elements defining a plurality of apertures aligned along sub-beam paths of the multi-beam and comprising:
- an objective lens array configured to project the multi-beam towards a sample;
- and
- a control lens array positioned up-beam of the objective lens array, the control lenses being configured to pre-focus the sub-beams;
- using the apertures defined in one or more of the planar elements to compensate for off-axis aberrations in the multi-beam, at least a subset of the apertures have a range of different aperture areas, the range of different aperture areas being selected to compensate for off-axis aberrations in the multi-beam;
- and
- using at least a subset of the apertures defined in the control lens array are provided at positions that are displaced relative to nominal positions, the displacements being selected to compensate for off-axis aberrations in the multi-beam.
4 more elements
Dependencies are inferred from the claim text.