Aberration-corrected multibeam source, charged particle beam device and method of imaging or illuminating a specimen with an array of primary charged particle beamlets
View Patent ↗A charged particle beam device for inspection of a specimen with an array of primary charged particle beamlets is described. The charged particle beam device includes a charged particle beam source to generate a primary charged particle beam; a multi-aperture plate having at least two openings to generate an array of charged particle beamlets having at least a first beamlet having a first resolution on the specimen and a second beamlet having a second resolution on the specimen; an aberration correction element to correct at least one of spherical aberrations and chromatic aberrations of rotational symmetric charged particle lenses; and an objective lens assembly for focusing each primary charged particle beamlet of the array of primary charged particle beamlets onto a separate location on the specimen.
1. A charged particle beam device for inspection of a specimen with an array of primary charged particle beamlets, comprising:
a charged particle beam source to generate a primary charged particle beam;
a multi-aperture plate having at least two openings to generate an array of primary charged particle beamlets having at least a first beamlet having a first resolution on the specimen and a second beamlet having a second resolution on the specimen;
an aberration correction element, provided between the charged particle beam source and the multi-aperture plate, to correct at least one of spherical aberrations and chromatic aberrations of rotationally symmetric charged particle lenses, and to correct the difference between the first resolution on the specimen and the second resolution on the specimen, the aberration correction element comprising two electric or magnetic quadrupole elements and at least two multipole elements, the at least two multipole elements comprising two combined electric-magnetic quadrupole elements; and
an objective lens assembly for focusing each primary charged particle beamlet of the array of primary charged particle beamlets onto a separate location on the specimen.
2. The charged particle beam device according to claim 1 , wherein the aberration correction element further comprises at least three electric or magnetic octupole elements.
3. The charged particle beam device according to claim 1 , wherein the at least two multipole elements generate at least two hexapole fields.
4. The charged particle beam device according to claim 1 , wherein the at least two multipole elements are two electrostatic quadrupole elements and the aberration correction element further comprises two electrostatic lenses.
5. The charged particle beam device according to claim 4 , wherein the aberration correction element further comprises at least three electric octupole elements.
6. The charged particle beam device according to claim 1 , wherein the aberration correction element focuses the primary charged particle beam to reduce a divergence between the first beamlet and the second beamlet.
7. The charged particle beam device according to claim 1 , further comprising:
a condenser lens assembly provided between the charged particle beam source and the multi-aperture plate.
8. The charged particle beam device according to claim 1 , wherein the objective lens assembly comprises an objective lens array to focus each beamlet of the array of primary charged particle beamlets individually.
9. The charged particle beam device according to claim 1 , wherein the objective lens assembly comprises a magnetic lens component acting on the array of primary charged particle beamlets.
10. The charged particle beam device according to claim 9 , further comprising:
a lens array provided between the multi-aperture plate and the objective lens assembly.
11. The charged particle beam device according to claim 10 , further comprising:
at least one of a lens or a deflector array, wherein the lens and the deflector array guides the array of primary charged particle beamlets through a coma free point of the objective lens assembly.
12. A method of imaging or illuminating a specimen with an array of primary charged particle beamlets, comprising:
generating an array of primary charged particle beamlets having at least a first beamlet and a second beamlet by illuminating a multi-aperture plate with a primary charged particle beam;
focusing the array of primary charged particle beamlets on the specimen with an objective lens assembly; and
correcting aberration differences between the first beamlet and the second beamlet with an aberration correction element according to claim 1 .
13. The method according to claim 12 , wherein the correcting the aberration differences is provided by the aberration correction element acting on the primary charged particle beam.
14. The method according to claim 12 , wherein correcting the aberration differences includes correcting off-axial aberrations of the objective lens assembly.
15. The method according to claim 12 , wherein the aberration correction element collimates the primary charged particle beam.
16. The method according to claim 12 , further comprising:
collimating the primary charged particle beam with a condenser lens assembly.
17. The charged particle beam device of claim 1 , wherein the at least two openings of the multi-aperture plate generate the array of primary charged particle beamlets from the primary charged particle beam.
18. A charged particle beam device for inspection of a specimen with an array of primary charged particle beamlets, comprising:
a charged particle beam source to generate a primary charged particle beam;
a multi-aperture plate having at least two openings to generate an array of charged particle beamlets having at least a first beamlet having a first resolution on the specimen and a second beamlet having a second resolution on the specimen;
an aberration correction element, provided between the charged particle beam source and the multi-aperture plate, to correct at least one of spherical aberrations and chromatic aberrations of rotationally symmetric charged particle lenses, and to correct the difference between the first resolution on the specimen and the second resolution on the specimen, wherein the aberration correction element comprises two electrostatic quadrupole elements and two electrostatic lenses; and
an objective lens assembly for focusing each primary charged particle beamlet of the array of primary charged particle beamlets onto a separate location on the specimen.
19. The charged particle beam device of claim 18 , wherein the aberration correction element further comprises at least three electric octupole elements.
20. The charged particle beam device of claim 18 , wherein the at least two openings of the multi-aperture plate generate the array of primary charged particle beamlets from the primary charged particle beam.