Multi-beam generating unit with increased focusing power
OwnerYanko Sarov, Dirk Zeidler +5inventors
InventorsYanko Sarov, Dirk Zeidler, Thomas Schmid, Georg Kurij, Marcus Kaestner, Ulrich Bihr, Wolfgang Singer
Life of this patent
Estimating the term…
Abstract
A multi-beam generation unit for a multi-beam system has larger individual focusing power for each of a plurality of primary charged particle beamlets. The multi-beam generation unit comprises an active terminating multi-aperture plate. The terminating multi-aperture plate can be used for a larger focusing range for an individual stigmatic focus spot adjustment of each beamlet of a plurality of primary charged particle beamlets.
Claims25
A multi-beam generation unit, comprising in order of a propagation direction of an incident primary charged particle beam:
- a filter plate comprising a plurality of first apertures configured to generate a plurality of primary charge particle beamlets, the filter plate configured to be connected to a ground level;
- a terminating multi-aperture plate comprising a plurality of terminating apertures and a first plurality of individually addressable electrodes, a circumference of each terminating aperture comprising a corresponding individually addressable electrode disposed therein;
- and
- a condenser lens comprising a condenser electrode comprising a single aperture configured to transmit the plurality of primary charged particle beamlets, the condenser electrode configured to generate a plurality of electrostatic micro-lens fields penetrating each of the plurality of terminating apertures;
- and
- a control unit configured to individually control the condenser electrode and each of the first plurality of individually addressable electrodes to influence the penetration depth and/or shape of each of the plurality of electrostatic micro-lens fields to independently adjust a lateral and/or axial focus position of each of the plurality of primary charge particle beamlets on an intermediate image surface to pre-compensate a field curvature and/or an image plane tilt of the multi-beam system.
A method of individually changing the focus distance of each of a plurality of primary charged particle beam spots, the method comprising:
- providing individually addressable terminating electrodes at each of a plurality of terminating apertures of a terminating multi-aperture plate;
- providing a condenser lens electrode adjacent to the terminating multi-aperture plate and downstream of the terminating multi-aperture plate in a propagation direction of a plurality of primary charged particle beamlets;
- using a control unit to provide a first voltage to the condenser lens electrode to generate a plurality of electrostatic micro-lens fields which penetrate the plurality of terminating apertures;
- using the control unit to provide individual voltages to each of the plurality of individually addressable electrodes;
- and
- individually controlling the plurality of individual voltages of the individually addressable terminating electrodes to influence the penetration depth of each of the plurality of electrostatic micro-lens fields to independently adjust an axial focus position of each primary charge particle beamlet on a curved intermediate image surface.
A multi-beam generation unit, comprising:
- a filter plate comprising a plurality of first apertures configured to generate a plurality of primary charge particle beamlets from an incident primary charged particle beamlet;
- a first multi-aperture plate comprising an electrode layer;
- a terminating multi-aperture plate comprising a plurality of terminating apertures;
- a condenser lens comprising a condenser electrode;
- and
- a control unit configured to provide a plurality of individual voltages to the at least a first multi-aperture plate, the terminating multi-aperture plate and the condenser electrode,
- wherein the multi-beam generation unit is configured to individually adjust an axial focus position of each of the plurality of primary charged particle beamlets with a focus range DF of more than 3 mm.
Dependencies are inferred from the claim text.