Apparatus of plural charged-particle beams
A multi-beam apparatus for observing a sample with high resolution and high throughput is proposed. In the apparatus, a source-conversion unit changes a single electron source into a virtual multi-source array, a primary projection imaging system projects the array to form plural probe spots on the sample, and a condenser lens adjusts the currents of the plural probe spots. In the source-conversion unit, the image-forming means is on the upstream of the beamlet-limit means, and thereby generating less scattered electrons. The image-forming means not only forms the virtual multi-source array, but also compensates the off-axis aberrations of the plurality of probe spots.
1. A charged-particle beam apparatus, comprising:
a charged particle source configured to provide a primary beam;
an image forming unit configured to form a plurality of images of the charged particle source using a plurality of beamlets of the primary beam;
a first projection system with an objective lens and configured to form a plurality of probe spots on a sample from the plurality of beamlets;
a second projection system configured to focus a plurality of secondary beams generated by the plurality of probe spots on the sample;
a beam separator configured to separate the plurality of beamlets and the plurality of secondary beams; and
a detection device with a plurality of detection elements configured to receive the plurality of secondary beams;
wherein the second projection system includes an anti-rotation magnetic lens configured to eliminate a rotation of the plurality of secondary beams on the detection device.
2. The charged-particle beam apparatus of claim 1 , wherein the first projection system includes a transfer lens to focus the plurality of beamlets to land on the sample perpendicularly.
3. The charged-particle beam apparatus of claim 1 , further comprising:
a deflection scanning unit configured to scan the plurality of probe spots on the sample.
4. The charged-particle beam apparatus of claim 1 , further comprising:
a beam-limiting element for limiting the plurality of beamlets with a plurality of beam-limit openings.
5. The charged-particle beam apparatus of claim 4 , further comprising:
a condenser lens configured to focus the primary beam to vary electric currents of the plurality of probe spots on the sample.