| CPC H01J 37/1474 (2013.01) [H01J 37/06 (2013.01); H01J 37/10 (2013.01); H01J 37/1477 (2013.01); H01J 37/1478 (2013.01); H01J 37/28 (2013.01); H01J 2237/024 (2013.01); H01J 2237/0453 (2013.01); H01J 2237/0492 (2013.01); H01J 2237/103 (2013.01); H01J 2237/1205 (2013.01); H01J 2237/1516 (2013.01); H01J 2237/1534 (2013.01); H01J 2237/1536 (2013.01)] | 20 Claims |

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1. A multi-beam apparatus for observing a surface of a sample, comprising:
a charged particle source configured to generate a charged particle beam;
a condenser lens configured to collimate the charged particle beam to be perpendicularly incident onto a source conversion unit that is configured to form a plurality of beamlets from the charged particle beam; and
an objective lens below the condenser lens,
wherein the source conversion unit comprises:
an image forming means including an array of micro-deflectors; and
a beamlet-forming plate above the array of micro-deflectors, the beamlet-forming plate including a plurality of beamlet-limit openings, wherein each beamlet-limit opening is aligned with a micro-deflector of the micro-deflector array to deflect one of the plurality of beamlets to pass through a front focal point of the objective lens such that the plurality of beamlets land perpendicularly on the surface of the sample and produce probe spots on the surface of the sample.
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