Multi-beam inspection apparatus with improved detection performance of signal electrons

1. A non-transitory computer readable medium storing a set of instructions that is executable by one or more processors of a charged particle beam system, including a secondary imaging system, to cause the charge particle beam system to perform a method to form images of a sample, the method comprising:

controlling a plurality of crossover-forming deflectors to deflect secondary electron beams to form a crossover area on a crossing plane at or near a beam-limit aperture of a beam-limit aperture plate for trimming the secondary electron beams, wherein the plurality of crossover-forming deflectors are positioned at or at least near an image plane of the secondary imaging system.

2. The computer readable medium of claim 1 , wherein the beam-limit aperture plateblocks off peripheral portions of each of the secondary electron beams.

3. The computer readable medium of claim 1 , wherein the beam-limit aperture platetrims the secondary electron beams to allow central portion of each of the secondary electron beams to pass through the beam-limit aperture.

4. The computer readable medium of claim 1 , wherein the set of instructions that is executable by the processor of the charged particle beam system to cause the charged particle beam system to further perform:

forming, by a first set of lenses, a first image plane of the secondary imaging system; and

forming, by a second set of lenses, a second image plane of the secondary imaging system.

5. The computer readable medium of claim 4 , wherein the plurality of crossover-forming deflectors are positioned at or at least near the first image plane of the secondary imaging system.

6. The computer readable medium of claim 5 , wherein the beam-limit aperture plate is positioned between the first set of lenses and the second set of lenses.

7. The computer readable medium of claim 5 , wherein the beam-limit aperture plate is positioned between the second set of lenses and an electron detection device.

8. The computer readable medium of claim 5 , wherein the beam-limit aperture plate is positioned within the second set of lenses.

9. The computer readable medium of claim 4 , wherein a first set of the plurality of crossover-forming deflectors are positioned at or at least near the first image plane of the secondary imaging system, and

a second set of the plurality of crossover-forming deflectors are positioned at or at least near the second image plane of the secondary imaging system.

10. The computer readable medium of claim 9 , wherein the set of instructions that is executable by the processor of the charged particle beam system to cause the charged particle beam system to further perform:

forming, by a third set of lenses, a third image plane of the secondary imaging system.

11. The computer readable medium of claim 10 , wherein the beam-limit aperture plate is positioned between the second set of lenses and the third set of lenses.

12. The computer readable medium of claim 10 , wherein the beam-limit aperture plate is positioned between the third set of lenses and an electron detection device.

13. The computer readable medium of claim 10 , wherein the beam-limit aperture plate is positioned within the third set of lenses.

14. A non-transitory computer readable medium storing a set of instructions that is executable by a processor of a charged particle beam system, including a secondary imaging system, to cause the charge particle beam system to perform a method to form images of a sample, the method comprising:

controlling a first set of electro-optical lenses to form a first image plane of the secondary imaging system; and

controlling a first set of crossover-forming deflectors to deflect a first set of a plurality of secondary electron beams to form a crossover area on a crossing plane at or near a beam-limit aperture of a beam-limit aperture plate for trimming the plurality of secondary electron beams,

wherein the first set of crossover-forming deflectors are positioned at or at least near the first image plane.

15. The computer readable medium of claim 14 , wherein the beam-limit aperture plateblocks off peripheral portions of the plurality of secondary electron beams.

16. The computer readable medium of claim 14 , wherein the set of instructions that is executable by the processor of the charged particle beam system to cause the charged particle beam system to further perform:

controlling a second set of electro-optical lenses to form a second image plane of the secondary imaging system.

17. The computer readable medium of claim 16 , wherein the set of instructions that is executable by the processor of the charged particle beam system to cause the charged particle beam system to further perform:

controlling a second set of crossover-forming deflectors to deflect a second set of the plurality of secondary electron beams to form the crossover area on the crossing plane at or near the beam-limit aperture of the beam-limit aperture plate, wherein the second set of crossover-forming deflectors are positioned at or at least near the second image plane.

18. The computer readable medium of claim 17 , wherein the beam-limit aperture plate is positioned between the first set of electro-optical lenses and the second set of electro-optical lenses.

19. The computer readable medium of claim 15 , wherein the beam-limit aperture plate is positioned between the second set of electro-optical lenses and an electron detection device.

20. The computer readable medium of claim 15 , wherein the beam-limit aperture plate is positioned within the second set of electro-optical lenses.