Charged-particle microscope with astigmatism compensation and energy-selection

A charged particle microscope, charged particle technology, applied in the field of corrected beams, can solve problems such as harmful effects, achieve extended use, reduce cost and complexity, and improve uptime

Active Publication Date: 2017-08-08
FEI CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0028] The problem with this known method is that it suffers from the deleterious effect of (double) astigmatism, especially associated with the intentionally off-centered transfer of the beam through the lens

Method used

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  • Charged-particle microscope with astigmatism compensation and energy-selection
  • Charged-particle microscope with astigmatism compensation and energy-selection
  • Charged-particle microscope with astigmatism compensation and energy-selection

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0078] figure 1 is a highly schematic depiction of an embodiment of a CPM in which the invention is implemented; more specifically, it shows an embodiment of a microscope M, which in this case is a SEM (although in the context of the present invention, its Could for example be (S)TEM, or ion-based microscopy, just right). Microscope M comprises an illuminator (particle-optical column) 1 which generates a beam 3 of input charged particles (in this case an electron beam) propagating along a particle-optical axis 3'. The illuminator 1 is mounted on a vacuum chamber 5 comprising a sample holder 7 and associated stage / actuator 7' for holding / positioning the sample S. The vacuum chamber 5 is evacuated using a vacuum pump (not depicted). With the help of a voltage source 17, the sample holder 7, or at least the sample S, can be biased (floated) to a potential relative to ground, if desired.

[0079] The illuminator 1 (in the present case) comprises an electron source 9 (such as, ...

Embodiment 2

[0091] Example 2

[0092] figure 2 schematically illustrates an embodiment of a method / corrector device according to the invention (see also figure 1 ) structure and operation. exist figure 2 In , the source 9 emits charged particles (such as electrons) in multiple directions, which are depicted here by the cones emanating from the tip of the source 9 . The spatial filter 31 (extractor aperture plate) comprises off-axis apertures 31a and on-axis apertures 31b considered relative to the optical axis 3'. The input beam 3a propagating from the source 9 through the aperture 31a passes eccentrically through the astigmatism corrector (quadrupole lens) 33 (centred on the axis 3') and emerges from the astigmatism corrector 33 as an intermediate beam 3b; On the other hand, the (axial) beam 3 a ′ passes non-eccentrically through the center of the astigmatism corrector 33 . As already explained above, the intermediate beam 3b will demonstrate (double) astigmatism and energy dis...

Embodiment 3

[0103] The following is an example of a direct astigmatism corrector adjustment (calibration) routine that can be used in the present invention:

[0104] (i) For the first of the line focuses (e.g. the distal line focus, furthest from the astigmatism corrector), one chooses a specific differential excitation of the astigmatism corrector (E D ) and adjust the non-differential excitation of the astigmatism corrector (E C ) for optimal focus at the slit plane. People then target E D Repeat the process for at least one other value of , allowing to make E C Contrast E D The first graph line of .

[0105] (ii) repeating the process in (i) for the second of the line focuses (proximal line focus, closest to the astigmatism corrector), resulting in E C Contrast E D the second graph line of .

[0106] (iii) E at the intersection of the first and second graph lines D The value of is the value that will minimize the axial separation of the first and second line focuses.

[0107] ...

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Abstract

The invention relates to a charged-particle microscope with astigmatism compensation and energy-selection. A method of producing a corrected beam of charged particles for use in a charged-particle microscope, comprising the following steps: - Providing a non-monoenergetic input beam 3a of charged particles; - Passing said input beam through an optical module comprising a series arrangement of: A stigmator 33, thereby producing an astigmatism-compensated, energy-dispersed intermediate beam 3b with a particular monoenergetic line focus direction; A beam selector 37, comprising a slit 43-43b' that is rotationally oriented so as to match a direction of the slit to said line focus direction, thereby producing an output beam 3d comprising an energy-discriminated portion of said intermediate beam.

Description

technical field [0001] The present invention relates to a method of generating a corrected beam of charged particles for use in a charged particle microscope. [0002] The invention also relates to a corrector device utilizing such a method. [0003] The invention also relates to a charged particle microscope comprising such a corrector device. [0004] The invention also relates to a method for calibrating / adjusting such a corrector device. Background technique [0005] Charged particle microscopy is a well-known and increasingly important technique for imaging microscopic objects, particularly in the form of electron microscopy. Historically, the basic class of electron microscopes has undergone evolution into several well-known device classes, such as transmission electron microscopes (TEM), scanning electron microscopes (SEM), and scanning transmission electron microscopes (STEM), and There has also been an evolution into various subcategories such as so-called "dual ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01J37/153H01J37/09
CPCH01J37/09H01J37/153H01J2237/153H01J37/05H01J37/28H01J2237/0453H01J2237/1532H01J37/26H01J2237/0451H01J2237/2826
Inventor B.塞达L.图马A.亨斯特拉
Owner FEI CO
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