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US 10,062,541 B2Granted
Apparatus of plural charged-particle beams
AssigneeHermes Microvision, Inc.
InventorsWeiming Ren, Xuedong Liu, Xuerang Hu, Zhongwei Chen
Life of this patent
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Abstract
A new multi-beam apparatus with a total FOV variable in size, orientation and incident angle, is proposed. The new apparatus provides more flexibility to speed the sample observation and enable more samples observable. More specifically, as a yield management tool to inspect and/or review defects on wafers/masks in semiconductor manufacturing industry, the new apparatus provide more possibilities to achieve a high throughput and detect more kinds of defects.
Claims79
A multi-beam apparatus for observing a surface of a sample, comprising:
- an electron source;
- a condenser lens below said electron source;
- a source-conversion unit below said condenser lens;
- an objective lens below said source-conversion unit;
- a deflection scanning unit below said source-conversion unit;
- a sample stage below said objective lens;
- a beam separator below said source-conversion unit;
- a secondary projection imaging system;
- and
- an electron detection device with a plurality of detection elements,
- wherein said electron source, said condenser lens and said objective lens are aligned with a primary optical axis of said apparatus, and said sample stage sustains said sample so that said surface faces to said objective lens,
- wherein said source-conversion unit comprises a beamlet-limit means with a plurality of beam-limit openings, and an image-forming means with a plurality of electron optics elements and movable along said primary optical axis,
- wherein said electron source generates a primary-electron beam along said primary optical axis and said condenser lens focuses said primary-electron beam,
- wherein a plurality of beamlets of said primary-electron beam pass through said plurality of beam-limit openings respectively, and is deflected by said plurality of electron optics elements towards said primary optical axis to form a plurality of virtual images of said electron source respectively,
- wherein said plurality of beamlets is focused by said objective lens onto said surface and therefore forms a plurality of probe spots thereon respectively, and said deflection scanning unit deflects said plurality of beamlets to scan said plurality of probe spots respectively over a plurality of scanned regions within an observed area on said surface,
- wherein a plurality of secondary electron beams is generated by said plurality of probe spots respectively from said plurality of scanned regions and directed into said secondary projection imaging system by said beam separator, said secondary projection imaging system focuses and keeps said plurality of secondary electron beams to be detected by said plurality of detection elements respectively, and each detection element therefore provides an image signal of one corresponding scanned region.
13 more elements
A multi-beam apparatus for observing a surface of a sample, comprising:
- an electron source;
- a condenser lens below said electron source;
- a source-conversion unit below said condenser lens;
- an objective lens below said source-conversion unit;
- a deflection scanning unit below said source-conversion unit;
- a sample stage below said objective lens;
- a beam separator below said source-conversion unit;
- a secondary projection imaging system;
- and
- an electron detection device with a plurality of detection elements,
- wherein said electron source, said condenser lens and said objective lens are aligned with a primary optical axis of said apparatus, and said sample stage sustains said sample so that said surface faces to said objective lens,
- wherein said source-conversion unit comprises a beamlet-limit means with a plurality of beam-limit openings, a first image-forming means with a plurality of first electron optics elements and a second image-forming means with a plurality of second electron optics elements, said second image-forming means is below said first image-forming means and movable in a radial direction, and one of said first image-forming means and said second image-forming means is used as an active image-forming means,
- wherein said electron source generates a primary-electron beam along said primary optical axis and said condenser lens focuses said primary-electron beam,
- wherein a plurality of beamlets of said primary-electron beam pass through said plurality of beam-limit openings respectively, and is deflected by said active image-forming means towards said primary optical axis to form a plurality of virtual images of said electron source respectively,
- wherein said plurality of beamlets is focused by said objective lens onto said surface and therefore forms a plurality of probe spots thereon respectively, and said deflection scanning unit deflect said plurality of beamlets to scan said plurality of probe spots respectively over a plurality of scanned regions within an observed area on said surface,
- wherein a plurality of secondary electron beams is generated by said plurality of probe spots respectively from said plurality of scanned regions and directed into said secondary projection imaging system by said beam separator, said secondary projection imaging system focuses and keeps said plurality of secondary electron beams to be detected by said plurality of detection elements respectively, and each detection element therefore provides an image signal of one corresponding scanned region.
13 more elements
An multi-beam apparatus for observing a surface of a sample, comprising:
- an electron source;
- a condenser lens below said electron source;
- a source-conversion unit below said condenser lens;
- an objective lens below said source-conversion unit;
- a deflection scanning unit below said source-conversion unit;
- a sample stage below said objective lens;
- a beam separator below said source-conversion unit;
- a secondary projection imaging system;
- and
- an electron detection device with a plurality of detection elements,
- wherein said electron source, said condenser lens and said objective lens are aligned with a primary optical axis of said apparatus, a first principal plane of said objective lens is movable along said primary optical axis, and said sample stage sustains said sample so that said surface faces to said objective lens,
- wherein said source-conversion unit comprises a beamlet-limit means with a plurality of beam-limit openings, and an image-forming means with a plurality of electron optics elements,
- wherein said electron source generates a primary-electron beam along said primary optical axis and said condenser lens focuses said primary-electron beam,
- wherein a plurality of beamlets of said primary-electron beam pass through said plurality of beam-limit openings respectively, and is deflected by said plurality of electron optics elements towards said primary optical axis to form a plurality of virtual images of said electron source respectively,
- wherein said plurality of beamlets is focused by said objective lens onto said surface and therefore forms a plurality of probe spots thereon respectively, and said deflection scanning unit deflects said plurality of beamlets to scan said plurality of probe spots respectively over a plurality of scanned regions within an observed area on said surface,
- wherein a plurality of secondary electron beams is generated by said plurality of probe spots respectively from said plurality of scanned regions and directed into said secondary projection imaging system by said beam separator, said secondary projection imaging system focuses and keeps said plurality of secondary electron beams to be detected by said plurality of detection elements respectively, and each detection element therefore provides an image signal of one corresponding scanned region.
13 more elements
A multi-beam apparatus for observing a surface of a sample, comprising:
- an electron source;
- a condenser lens below said electron source;
- a source-conversion unit below said condenser lens;
- a transfer lens below said source-conversion unit;
- a field lens below said transfer lens;
- an objective lens below said field lens;
- a deflection scanning unit below said source-conversion unit;
- a sample stage below said objective lens;
- a beam separator below said source-conversion unit;
- a secondary projection imaging system;
- and
- an electron detection device with a plurality of detection elements,
- wherein said electron source, said condenser lens, said transfer lens, said field lens and said objective lens are aligned with a primary optical axis of said apparatus, and said sample stage sustains said sample so that said surface faces to said objective lens,
- wherein said source-conversion unit comprises a beamlet-limit means with a plurality of beam-limit openings, and an image-forming means with a plurality of electron optics elements,
- wherein said electron source generates a primary-electron beam along said primary optical axis and said condenser lens focuses said primary-electron beam,
- wherein a plurality of beamlets of said primary-electron beam pass through said plurality of beam-limit openings respectively, and is deflected by said plurality of electron optics elements towards said primary optical axis to form a plurality of first virtual images of said electron source respectively,
- wherein said transfer lens images said plurality of first virtual images onto an intermediate image plane and therefore forms a plurality of second real images respectively thereon, said field lens is placed on said intermediate image plane and bends said plurality of beamlets, said objective lens images said plurality of second real images onto said surface and therefore forms a plurality of probe spots thereon respectively, and said deflection scanning unit deflects said plurality of beamlets to scan said plurality of probe spots respectively over a plurality of scanned regions within an observed area on said surface,
- wherein a plurality of secondary electron beams is generated by said plurality of probe spots respectively from said plurality of scanned regions and directed into said secondary projection imaging system by said beam separator, said secondary projection imaging system focuses and keeps said plurality of secondary electron beams to be detected by said plurality of detection elements respectively, and each detection element therefore provides an image signal of one corresponding scanned region.
15 more elements
A method to configure a multi-beam apparatus for observing a surface of a sample, comprising steps of:
- configuring an image-forming means of a source-conversion unit movable along a primary optical axis thereof;
- using said image-forming means to form a plurality of virtual images of an electron source respectively;
- using an objective lens to image said plurality of virtual images onto said surface and form a plurality of probe spots thereon;
- and
- moving said image-forming means to vary pitches of said plurality of probe spots.
2 more elements
A method to configure a multi-beam apparatus for observing a surface of a sample, comprising steps of:
- configuring a source-conversion unit with a first image-forming means and a second image-forming means, wherein said second image-forming means is farther away from an electron source than said first image-forming means and movable in a radial direction of said apparatus;
- using one of said first image-forming means and said second image-forming means as an active image-forming means, wherein when said first image-forming means is used, said second image-forming means is moved away;
- using said active image-forming means to form a plurality of virtual images of said electron source respectively;
- using an objective lens to image said plurality of virtual images onto said surface and form a plurality of probe spots thereon;
- and
- changing said active image-forming means between said first image-forming means and said second image-forming means to vary pitches of said plurality of probe spots.
3 more elements
A method to configure a multi-beam apparatus for observing a surface of a sample, comprising steps of:
- configuring an objective lens with a first principal plane movable along a primary optical axis of said apparatus;
- using an image-forming means of a source-conversion unit to form a plurality of virtual images of an electron source respectively;
- using said objective lens to image said plurality of virtual images onto said surface and form a plurality of probe spots thereon;
- and
- moving said first principal plane to vary pitches of said plurality of probe spots.
2 more elements
A method to configure a multi-beam apparatus for observing a surface of a sample, comprising steps of:
- configuring an objective lens with a lower magnetic lens and an electrostatic lens in said apparatus;
- using an image-forming means of a source-conversion unit to form a plurality of virtual images of an electron source respectively;
- using said objective lens to image said plurality of virtual images onto said surface and form a plurality of probe spots thereon;
- and
- changing a ratio of focusing powers of said magnetic lens and said electrostatic lens to select an orientation of said plurality of probe spots.
2 more elements
A method to configure a multi-beam apparatus for observing a surface of a sample, comprising steps of:
- using an image-forming means of a source-conversion unit to deflect a plurality of beamlets from an electron source to form a plurality of first virtual images thereof respectively;
- using an objective lens to image said plurality of virtual images onto said surface and form a plurality of probe spots thereon;
- and
- setting deflection angles of said plurality of beamlets due to said image-forming means so that said plurality of beamlets lands on said surface with same or substantially same landing angles.
1 more element
A method to configure a multi-beam apparatus for observing a surface of a sample, comprising steps of:
- using an image-forming means of a source-conversion unit to deflect a plurality of beamlets from an electron source to form a plurality of first virtual images thereof respectively;
- using a transfer lens to image said plurality of first virtual images onto an intermediate image plane and forms a plurality of second real images respectively;
- placing a field lens on said intermediate image plane to bend said plurality of beamlets;
- and
- using an objective lens to image said plurality of second real images onto said surface and form a plurality of probe spots thereon.
2 more elements
An apparatus, comprising:
- a source for providing a primary charged particle beam;
- a source-conversion unit for dividing the primary charged particle beam into a plurality of charged particle beamlets and using which to form a plurality of images of the source respectively;
- an objective lens below said source-conversion unit for projecting the plurality of images onto a sample surface;
- wherein pitches of the plurality of charged particle beamlets on the sample surface are adjustable by changing deflection angles of the plurality of charged particle beamlets prior entering the objective lens.
1 more element
An apparatus, comprising:
- a source for providing a primary charged particle beam;
- means for using a plurality of beamlets of the primary charged particle beam to form a plurality of images of the source;
- an objective lens for projecting the plurality of images onto a sample surface to form a plurality of probe spots;
- and
- means for adjusting pitches of the plurality of probe spots on the sample surface.
2 more elements
A method for observing a sample surface, said method comprising steps of:
- providing a plurality of charged particle beams with a plurality of crossovers respectively;
- projecting the plurality of crossovers onto the sample surface to form a plurality of probe spots thereon;
- scanning the plurality of probe spots on the sample surface;
- and
- changing deflection angles of the plurality of charged particle beams such that pitches of the plurality of spots can be adjusted.
2 more elements
Dependencies are inferred from the claim text.