Charged particle optical apparatus for through-the-lens detection of particles

A charged particle optical apparatus, comprising:

• a particle optical arrangement, configured to define a primary particle beam path for inspecting an object;
• a specimen chamber configured to accommodate an object in a pressure-controlled interior of the specimen chamber during the inspection of the object;
• a differential pressure module having at least one differential pressure aperture;
• a first detector, wherein the first detector is a gaseous detector;
• and
• a second detector, wherein the second detector is a semiconductor detector having at least one particle receiving surface arranged circumferentially around the primary particle beam path;
• wherein the first detector includes a collector electrode,
• wherein the collector electrode extends around the primary particle beam path;
• wherein the first detector and the second detector are mounted on a common mounting structure;
• and
• wherein the collector electrode has an end portion closer to an interaction region than the at least one particle receiving surface, wherein the interaction region is a region where a primary particle beam generated by the particle optical apparatus interacts with the object during the inspection of the object.

A method of operating a charged particle optical apparatus, wherein the charged particle optical apparatus comprises:

• a particle optical arrangement, configured to define a primary particle beam path for inspecting an object;
• a specimen chamber configured to accommodate an object in a pressure-controlled interior of the specimen chamber during the inspection of the object;
• a differential pressure module having a differential pressure aperture;
• a first detector, wherein the first detector is a gaseous detector, wherein the first detector comprises plural collector electrodes distributed around the primary particle beam path;
• a second detector, wherein the second detector is a semiconductor detector having plural particle receiving surfaces distributed around the primary particle beam path,
• wherein first detector and the second detector are mounted on a common mounting structure;
• and
• wherein the method comprises:
• comparing signals outputted by the first detector with signals outputted by the second detector.

A method of operating a charged particle optical apparatus, wherein the charged particle optical apparatus comprises:

• a particle optical arrangement, configured to define a primary particle beam path for inspecting an object;
• a specimen chamber configured to accommodate an object in a pressure-controlled interior of the specimen chamber during the inspection of the object;
• a differential pressure module having at least one differential pressure aperture;
• a first detector, wherein the first detector is a gaseous detector;
• and
• a second detector, wherein the second detector is a semiconductor detector having at least one particle receiving surface arranged circumferentially around the primary particle beam path;
• wherein the first detector includes a collector electrode,
• wherein the collector electrode extends around the primary particle beam path;
• wherein the first detector and the second detector are mounted on a common mounting structure;
• wherein the collector electrode has an end portion closer to an interaction region than the at least one particle receiving surface, wherein the interaction region is a region where a primary particle beam generated by the particle optical apparatus interacts with the object during the inspection of the object;
• and
• wherein the method comprises:
• comparing signals outputted by the first detector with signals outputted by the second detector.