Sixth order or higher STEM multipole corrector

Abstract

To provide a technique to correct axial aberrations of a particle-optical lens in a charged particle microscope system.SOLUTION: A multipole corrector 100 includes a first primary multipole 102 that generates a first primary multipole field when a first excitation is applied to the first primary multipole, and a second primary multipole 104 that generates a second primary multipole field when a second excitation is applied to the second primary multipole. The second primary multipole 104 is positioned between the first primary multipole 102 and a lens which is the source of spherical aberration. The multipole corrector also includes a secondary multipole 112 for correcting a fourth-order aberration and a sixth-order aberration generated by the first primary multipole 102, and further includes a tertiary multipole 114 for correcting an eighth-order aberration.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] Particle-optical microscopes utilize circular lenses to direct an electron / charged particle beam to illuminate a sample. However, circular lenses produce a positive spherical aberration coefficient, which limits higher opening angles and inhibits resolution and probe current. To address this issue, current particle-optical microscopes incorporate multipole correctors to reduce and / or correct the spherical aberration. In a hexapole corrector, the primary multipole is carefully aligned so that the fourth-order three-lobe aberration D4 is zero. Imaging For example, the hexapole corrector invented by Rose in 1990 has two powerful identical hexapoles. The two powerful hexapoles in the Rose corrector are carefully aligned with each other with a magnification of -1. Imaging When this is done, their lowest order effects (i.e., triple astigmatism A2) are cancelled and the fourth order three-lobe aberration D4 is nullified. Imaging This is to separate the mid-planes of the hexapoles from each other. Imaging (i.e., the intermediate planes are exactly conjugate).

[0002] However, in this method, the multipole intermediate surfaces are Imaging is not the only way to nullify the D4 aberration in current practice. For example, in some other hexapole corrector types (e.g., hexapole correctors that include more than one primary hexapole), a large aberration D4 is produced if the midplanes of all the primary hexapoles are exactly conjugate to each other. In such hexapole correctors, to nullify D4, the midplane of one primary hexapole is conjugated to a plane that is adjacent to the midplanes of the other primary hexapoles, and the planes are not all the same as the midplanes of the other primary hexapoles.

[0003] In conventional multipole correctors, the fourth-order three-lobe aberration D4 is zero, but conventional multipole correctors also produce various higher-order aberrations (e.g., sixth-order three-lobe aberration D6, eighth-order three-lobe aberration D8, etc.) that limit the resolution of the microscope. For example, the S-CORR corrector described in U.S. Pat. No. 8,841,630 does not have 6-fold astigmatism, but aberrations such as the sixth-order three-lobe aberration D6 and the eighth-order three-lobe aberration D8 are not canceled. Therefore, even if current hexapole correctors (such as the Rose corrector and the S-CORR corrector) are mechanically perfect, current particle optical microscopes that employ them are limited by sixth-order aberrations (i.e., sixth-order three-lobe aberration D6). For this reason, sixth-order aberrations are the limiting factor for the resolution of current charged particle optical microscopes that employ hexapole correctors. Imaging This is a fundamental barrier that limits the capabilities of current charged particle optical microscopes that employ quadrupole-octupole correctors. For the same reason, current charged particle optical microscopes that employ quadrupole-octupole correctors are limited by seventh-order aberrations. It is therefore desirable to reduce the high-order aberrations of such Cs correctors. Summary of the Invention

[0004] A corrector for correcting axial aberrations of a particle-optical lens in a charged particle microscope system according to the present disclosure includes a first primary hexapole that generates a first primary hexapole field when a first excitation voltage or current is applied to the first primary hexapole, and a second primary hexapole that is disposed between the first primary hexapole and a lens that is a source of spherical aberration when the corrector is used in the charged particle microscope system. In the remainder of this document, this lens may be referred to as the particle-optical lens. Generally, the lens that is the main source of spherical aberration is the lens that acts as the objective lens in the charged particle microscope system. The second primary hexapole generates a second primary hexapole field when a second excitation is applied to the second primary hexapole. According to some embodiments of the present disclosure, the first primary hexapole is carefully positioned on the second primary hexapole. ImagingInstead, a slightly misaligned image of the first primary hexapole on the second primary hexapole results in combined fourth order aberrations. In such an embodiment, the corrector includes a secondary hexapole for correcting fourth and sixth order aberrations, the secondary hexapole being disposed between the second primary hexapole and the particle-optical lens when the corrector is used in a charged particle microscope system. Such a corrector may further include a tertiary hexapole disposed between the second primary hexapole and the particle-optical lens for correcting eighth order aberrations.

[0005] In an alternative embodiment of the present disclosure, a corrector for correcting axial aberrations of a particle-optical lens can include a first primary hexapole for generating a first primary hexapole field when a first excitation is applied to the first primary hexapole, and a second primary hexapole disposed between the first primary hexapole and the particle-optical lens when the corrector is used in a charged particle microscope system, the second primary hexapole generating a second primary hexapole field when a second excitation is applied to the second primary hexapole, and the first primary hexapole being disposed on the second primary hexapole according to conventional practice. ImagingIn such an embodiment, the corrector further includes a secondary hexapole disposed between the second primary hexapole and the particle-optical lens when the corrector is used in a charged particle microscope system. The secondary hexapole is configured to generate a third hexapole field when a third excitation is applied to the secondary hexapole. An alternative embodiment further includes a tertiary hexapole disposed between the second primary hexapole and the particle-optical lens. The tertiary hexapole is configured to generate a fourth hexapole field when a fourth excitation is applied to the tertiary hexapole. The secondary and tertiary hexapoles are positioned and / or otherwise configured such that the third and fourth hexapole fields correct the sixth order aberration D6. Additionally, a corrector according to the present disclosure may include other types of multipoles instead of hexapoles, such as dipoles, quadrupoles, etc. For example, correctors using quadrupole and octopole fields instead of hexapoles according to the present disclosure can use similar phenomena to those described above to correct intrinsic and parasitic higher order aberrations, e.g., quadratic and cubic octopole fields can correct four-fold aberrations up to the seventh order. [Brief description of the drawings]

[0006] The detailed description will be set forth with reference to the accompanying drawings, in which the left-most digit(s) of a reference number indicates the figure in which that reference number first appears, and the same reference numbers in different drawings indicate similar or identical items. [Figure 1] 1 illustrates an exemplary multipole corrector for correcting sixth order and / or higher order aberrations in accordance with the present invention. [Diagram 2] 2 shows a collective diagram 200 illustrating the optical behavior of the corrector transfer optics of a prior art corrector and a sixth order corrector STEM multipole corrector system according to the present disclosure. [Diagram 3] 1 shows an exemplary charged particle microscope system for inspecting components of a sample 302 that includes a sixth order STEM multipole corrector system 100 in an optical column in accordance with the present invention. [Figure 4]1 illustrates an exemplary charged particle microscope system including a sixth order corrected STEM multipole corrector system 100 having three primary multipoles, where at least two primary multipoles are not imaged to one another. [Diagram 5] 1 is a diagram showing the optical performance of a conventional corrector system. [Figure 6] 1 is a diagram illustrating the optical performance of a sixth order STEM multipole corrector system according to the present disclosure. [Figure 7] 13 shows the optical performance of a corrected STEM multipole corrector system where the primary multipoles are not imaged onto one another and the second primary multipole is asymmetrically displaced. [Figure 8] 1 illustrates the optical performance of an exemplary STEM multipole corrector system having an asymmetric ray path. [Figure 9] An exemplary multipole corrector system for correcting sixth order aberrations is shown, which includes at least a pair of primary multipoles imaged to each other and a number of multipoles positioned downstream of the pair of primary multipoles arranged and / or otherwise configured to produce aberrations that combine to correct sixth order or higher aberrations. [Figure 10] 1 illustrates an exemplary charged particle microscope system including an exemplary multipole corrector system for correcting sixth order aberrations that includes at least a pair of primary multipoles imaged together. [Figure 11] 1 is a diagram showing how sixth-order aberrations are corrected by combining the aberrations of a first primary multipole, a second primary multipole, and a secondary multipole in a sixth-order corrector STEM multipole corrector system. [Figure 12] An exemplary multipole imaging corrector system for correcting sixth order aberrations is shown, which includes at least a pair of primary multipoles imaged to each other and a number of multipoles positioned downstream of the pair of primary multipoles arranged and / or otherwise configured to produce aberrations that combine to correct sixth order or higher aberrations. [Figure 13]An exemplary multipole corrector system for correcting sixth order aberrations is shown, which includes at least a pair of primary multipoles imaged to each other and a number of multipoles positioned downstream of the pair of primary multipoles arranged and / or otherwise configured to produce aberrations that combine to correct sixth order or higher aberrations. [Figure 14] Flat Ronchigram image produced by a microscope system with a conventional correction system, limited by D6. [Figure 15] FIG. 11 is a flat Ronchigram image produced by a microscope system equipped with a sixth-order STEM multipole corrector system. [Figure 16] FIG. 1 is a flat Ronchigram image produced by a microscope system with a 6th and 8th order corrected STEM multipole corrector system, where both D6 and D8 are significantly reduced. Like reference numerals refer to corresponding parts throughout the several views of the drawings. Generally, in these figures, elements that are likely to be included in a given example are shown in solid lines, whereas elements that are optional for a given example are shown in dashed lines. However, elements shown in solid lines are not required for all examples of the present disclosure, and elements shown in solid lines may be omitted from a particular example without departing from the scope of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Included herein are multipole correctors for correcting sixth order aberrations and / or higher order aberrations. More specifically, the multipole correctors disclosed herein are configured to correct sixth order three-lobe D6 aberrations in charged particle microscope systems. Multipole correctors according to some embodiments of the present invention are Imaging The corrector includes at least one pair of primary multipoles that are not polarized and generate fourth-order combined aberrations, and a secondary multipole that is disposed between the pair of primary multipoles and a lens that is a source of spherical aberration (e.g., an objective lens of the charged particle microscope system) when the corrector is used in the charged particle microscope system.

[0008] In some embodiments, the lens may be the lens that is the main source of spherical aberration when the corrector is used in a charged particle microscope system (i.e., the source that generates the most spherical aberration in the system, the source that generates a large amount of spherical aberration in the system). The second order multipole is configured to correct fourth and sixth order aberrations. The correction of aberrations according to the present disclosure corresponds to positive aberrations counterbalanced by negative aberrations such that their sum is zeroed, substantially zeroed, and / or reduced to an optimal value (e.g., their sum is reduced to a value that combines with one or more other aberrations to balance / correct higher order aberrations). Furthermore, the terms multipole, quadrupole, hexapole, quadrupole-octopole, etc. are used herein to describe multipole fields, quadrupole fields, hexapole fields, quadrupole-octopole fields, etc., and not physical devices configured to generate these fields.

[0009] That is, the disclosed embodiments of the invention correct aberrations via novel aberrations that, when combined, correct 6th order aberrations. Furthermore, as disclosed below, in some embodiments of the disclosed invention, the combinations of aberrations created can be combined to correct 8th order aberrations. Specifically, Imaging The uncoupled pair of primary multipoles generates significant fourth-order aberrations, which combine with the aberrations generated by the novel secondary multipoles to cancel both the fourth- and sixth-order aberrations.

[0010] Moreover, multipole correctors according to some other embodiments of the present invention may be arranged such that they are mutually exclusive according to conventional practice. Imaging or substantially Imagingand a plurality of multipoles disposed between the pair of primary multipoles and the particle-optical lens when the corrector is used in a charged particle microscope system. The plurality of multipoles are arranged and / or otherwise configured to produce aberrations that combine to correct for sixth or higher order aberrations. That is, each multipole disposed between the pair of primary multipoles and the particle-optical lens can be arranged and set at a particular excitation level to produce an aberration that combines with other aberrations produced by the corrector system to cancel out up to sixth or eighth order aberrations.

[0011] The following procedure demonstrates the performance of an exemplary corrector system according to the present disclosure. Specifically, the following procedure demonstrates the performance of a probe hexapole corrector according to the present disclosure having (i) parallel (or nearly parallel) entrance and exit beams, (ii) identical geometry between the primary hexapoles, (iii) only two primary hexapoles, and (iv) a corrector upstream of the particle-optical lens (as in an SEM or STEM). However, as described below, correctors according to the present disclosure are not limited to such embodiments, but rather correctors with other characteristics that operate according to similar phenomena (e.g., quadrupole-octopole instead of hexapole, with additional primary hexapole for microscope systems other than STEM designed to be placed downstream of the sample from the system's charged particle source, non-parallel exit beam, asymmetric hexapole corrector, asymmetric beam path, etc.) can be constructed according to the present disclosure. For example, if an exemplary corrector system according to the present disclosure is designed to be placed downstream of the sample from the charged particle source of the system (e.g., a corrector for a TEM system), the arrangement of the hexapoles within the corrector will be reversed (i.e., the secondary hexapole(s) will be closer to the charged particle source than the primary hexapole, but the second hexapole will still be located between the first and secondary hexapole(s)).

[0012] As an example, we will consider in detail the case of a corrector with two primary hexapoles. Neglecting the fringe fields, the scalar magnetic potential of the hexapoles is given by

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[0013] The phase function that accounts for all terms allowed by three-fold symmetry up to the seventh order for the hexapole of the systems disclosed herein is given by:

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[0014] The action of each of the pair of primary hexapoles is approximated by the following equation:

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[0015] Consider the case where a parallel beam is incident on the first primary hexapole and the complex transverse position of an electron in this beam = U0. According to the invention, the intermediate result (u1, u'1) at the asymptotic mid-plane of the downstream primary hexapole is at most 4th order at u0.

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[0016] Rewriting equation (8) in terms of u1 gives us the following:

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[0017] In the first method, the drift distance between the downstream primary hexapole and the second hexapole is taken as d, the action of the secondary hexapole is taken as k3, and the inverse extrapolation is applied to the center of the downstream primary hexapole. This results in the following relationship:

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[0018] JPEG0007622337000019.jpg1540 By inverting the Taylor series of can be written as a function of JPEG0007622337000020.jpg1534, resulting in

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[0019] Equation (15) can be converted to position aberration.

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[0020] These relationships can be used to construct a corrector according to the present disclosure that corrects for sixth-order three-lobe D6 aberrations in a charged particle microscope system. That is, a corrector having a secondary multipole hexapole downstream of a pair of primary hexapoles can be positioned and / or otherwise configured such that the corrector corrects for sixth-order aberrations. For example, 6,cor is equal to 3 mm, the above relationship means that the aberration A 2s , D 4s , and D. 6scan be corrected by a hexapole shift △z=0.5mm, where L=16mm, C3=1.4mm, d=35mm, and f eff = 1.6 mm. As will be explained further below, the hexapole shift Δz is the distance between the pair of primary hexapoles. Imaging or by physically displacing the pair of primary hexapoles so that they are not Imaging This can be achieved by modifying the excitation of the two transfer lenses between the primary hexapole so that the reflected light is not reflected by the primary hexapole, or by a combination thereof.

[0021] The second way of proceeding from equations (1)-(9) to equations (12, 13, 14) considers a probe corrector with a parallel beam at the exit plane and a number of multipoles treated with a thin lens approximation. In free space downstream of the corrector, the phase function (S(x, y, z)) is governed by the eikonal equation described in Harald Rose's "Geometrical Charged-Particle Optics" (Springer, 2009), equation 2.21, where the potential is constant and the vector potential is zero. This free-space phase function is therefore

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[0022] Relations (20)-(22) can be used to construct a corrector according to the present disclosure that corrects for sixth-order three-lobe aberrations in a charged particle microscope system, since relations (20)-(22) contain three degrees of freedom (i.e., the delta excitation k2 is JPEG0007622337000043.jpg1725 is the source, and excitation k3 is This is the source of JPEG0007622337000044.jpg1621, and △z is These three degrees of freedom are the source of JPEG0007622337000045.jpg2022. These three degrees of freedom are the source of JPEG0007622337000045.jpg2022. These three degrees of freedom are the source of JPEG0007622337000045.jpg2022. These three degrees of freedom are the source of JPEG0007622337000045.jpg2022. These three degrees of freedom are the source of JPEG0007622337

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[0023] Furthermore, in some embodiments, the corrector system according to the invention may include multiple secondary multipoles between the pair of primary multipoles and the objective lens when the corrector system is used in a charged particle microscope. For example, the corrector system may include a first secondary multipole downstream of the pair of primary multipoles, and a second secondary multipole downstream of the first secondary multipole. To determine the triple aberration of such a system, equation (17) can be used to calculate the coefficient JPEG0007622337000047.jpg1855 and then extrapolate back to the corrector exit plane using the inverse of equation (17) twice. In the first iteration, these two calculations can be done over the drift distance d1 associated with the first secondary multipole, and in the second iteration, the calculations can be done over the drift distance d2 associated with the second secondary multipole. An example of a visualization of this process is shown in FIG. 9. Furthermore, note that the following processing corresponds to the special case where lenses 908 and 910 (FIG. 9) are not excited. In other cases, the principle remains the same, but the analytical calculations are different. This two iterations of the process result in the following three-fold aberrations in the corrector system:

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[0024] These relationships are provided when a corrector system according to the present disclosure includes a pair of primary hexapoles having a particular hexapole shift, includes two or more secondary hexapoles disposed downstream of the pair of primary hexapoles, and / or otherwise has a combination of aberrations of the corrector system

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[0025] Alternatively, these relationships can be used for the triple aberration of such a corrector system to allow a pair of primary multipoles to be aligned relative to one another while correcting for sixth-order three-lobe aberrations in accordance with the present disclosure. ImagingThis allows the construction of a corrector system in which all the primary hexapoles are Imaging This has the advantage that the second-order off-axis astigmatism is smaller than in the non-existent embodiment.

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[0026] FIG. 1 is a diagram of an exemplary multipole corrector 100 for correcting sixth-order and / or higher-order aberrations according to the present invention. The description and arrows in FIG. 1 are specific to a probe corrector in a SEM or STEM system. The exemplary multipole corrector 100 includes at least a first primary multipole 102 and a second primary multipole 104. A multipole is an optical element for generating an electromagnetic field that exhibits n / 2-fold rotational symmetry, where n is an even integer. Thus, examples of multipoles include dipoles, quadrupoles, hexapoles, etc. For example, a multipole with eight yokes / electrodes can generate dipole, quadrupole, and hexapole fields in any orientation.

[0027] During operation of the SEM or STEM system, the charged particle beam 106 is directed along a central axis 108 to a first end 110 of the multipole corrector. The second primary multipole 104 is located between the first primary multipole 102 and a particle-optical lens when the corrector is used in a charged particle microscope system. For example, the second primary multipole 104 is shown in FIG. 1 as being located downstream of the first primary multipole 102 (i.e., the charged particle beam 106 interacts with the first primary multipole 102 before interacting with the second primary multipole 104). An excitation is applied to each of the first primary multipole 102 and the second primary multipole 104, which generate an electromagnetic field that directs the charged particle beam 106 to be incident on the sample. In an embodiment in which the corrector 100 is designed to operate within a TEM system, the corrector 100 is positioned downstream of the sample and the charged particle beam 108 interacts with the second primary multipole 104 before interacting with the first primary multipole 102.

[0028] In accordance with the present invention, the contributions of the first primary multipole element 102, the second primary multipole element 104, and the transfer optics therebetween produce a significant triple astigmatism A2 and a significant fourth-order three-lobe aberration D4. In various embodiments, this failure to disable A2 and D4 is due to: the excitation applied to the second primary multipole 104 being greater than the excitation applied to the first primary multipole 102; the first primary multipole 102 and the second primary multipole 104 having different lengths (i.e., L1 and L2); the first primary multipole 102 and the second primary multipole 104 having different beam radii; the first primary multipole 102 and the second primary multipole 104 having different dimensions of the magnetic yoke; asymmetry in the transfer lens 118 between the first primary multipole 102 and the second primary multipole 104; asymmetry in the ray path of the charged particle beam 106 between the first primary multipole 102 and the second primary multipole 104; ImagingThis is likely the result of the correction being prevented from being applied to the 6th order aberrations, or a combination thereof. Instead, in accordance with the present invention, one or more of these aspects of the corrector described herein are adjusted and / or employed to correct for 6th order aberrations and / or higher order aberrations. As used herein, the term "excitation" applied to a multipole refers to an excitation voltage or current applied to the corresponding multipole. For example, in an embodiment in which the corrector 100 is used in an electron microscope column, the excitation may refer to a current applied to a particular multipole that causes the particular multipole to generate a multipole field.

[0029] In the prior art corrector 100, the constituent multipoles are spaced apart from one another to prevent aberrations. Imaging However, in an exemplary multipole corrector 100 for correcting sixth order aberrations and / or higher order aberrations, a first primary multipole element 102 is mounted on a second primary multipole element 104. Imaging For example, if the first primary multipole element 102 and the second primary multipole element 104 are each hexapoles, this will generate significant fourth-order aberrations. Imaging The first primary multipole 102 not aligned corresponds to one or more of the multipole mid-planes of the first primary multipole 102 and the second primary multipole 104 being displaced along the central axis 108. For example, each of the first primary multipole 102 and the second primary multipole 104 can be displaced in opposite directions along the central axis 108 by up to 0.1 mm, 0.5 mm, 1 mm, 0.1%, 0.5%, 1% or more of the distance between the two primary hexapoles. Furthermore, the charged particle beam 106 can be incident on the first primary multipole 102 at an angle non-parallel to the central axis 108. For example, excitation can be applied to one or more lenses upstream of the exemplary multipole corrector 100 such that the one or more lenses cause the charged particle beam to be incident on the first primary multipole 102 at an angle non-parallel to the central axis 108.

[0030] 1 further illustrates the exemplary multipole corrector 100 as including a secondary multipole 112 disposed between the second primary multipole 104 and a particle-optical lens when the corrector is used within a charged particle microscope system (e.g., downstream of the second primary multipole 104 in a SEM / STEM system and upstream of the second primary multipole 104 in a TEM system). The secondary multipole 112 is configured to: (i) direct a multipole field generated by the secondary multipole 112 onto the second primary multipole 104; Imaging The secondary multipole 112 is positioned, excited, and / or otherwise configured to correct (i) aberrations generated by the first primary multipole 102 that are not reflected by the first primary multipole 104, and (ii) higher order aberrations. For example, if the secondary multipole 112 is a hexapole, the multipole field generated by the secondary multipole 112 will (i) be incident on the second primary multipole 104. Imaging and (ii) sixth order aberrations generated by the first primary multipole element 102 not coupled to the first primary multipole element 102.

[0031] For example, the change in excitation between the first and second multipole elements 102 and 104 acts as a shift, which is a first degree of freedom, Δz acts as a second degree of freedom (resulting in a D4 aberration that scales proportionally to the shift), and the excitation of the secondary multipole element 112 acts as a third degree of freedom. By adjusting these values, the exemplary multipole corrector 100 can generate controlled A2 and D4 aberrations (i.e., A2 depends on the excitation value of the secondary multipole element 112 and the change in excitation between the first multipole element 102 and the second multipole element 104, and D4 depends on the excitation value and shift of the secondary multipole element 112). By adjusting the values, it is also possible to generate additional aberrations that depend on the excitation value of the secondary multipole element 112, which are the D 6,cor , which, in combination with the , corrects the D6 aberration of the system. Thus, these values ​​for the exemplary multipole corrector 100 are such that second, fourth, and sixth order aberrations are corrected.

[0032] Thus, during operation of such a charged particle microscope, if the exemplary multipole corrector 100 includes a hexapole, the exemplary multipole corrector 100 corrects the sixth order three-lobe D6 aberration. In some embodiments, the exemplary multipole corrector 100 may optionally include a cubic multipole 114 disposed between the secondary multipole 112 and the particle-optical lens when the corrector is used within a charged particle microscope system. Such a cubic multipole 114 may be positioned, excited, and / or otherwise configured such that the multipole field generated by the cubic multipole 114 corrects even higher order aberrations (e.g., if the cubic multipole 114 is a hexapole, it may correct eighth order aberrations).

[0033] According to the present disclosure, the contributions to the 3x astigmatism A2 due to the first primary hexapole 102, the second primary hexapole 104, the secondary multipole 112, and the optional tertiary multipole 114 sum to zero.

[0034] In some embodiments, the exemplary multipole corrector 100 may include an intermediate multipole 116 and / or one or more transfer lenses 118. Additionally, although not shown in FIG. 1, the exemplary multipole corrector 100 may also optionally include a third primary multipole. Such a third primary multipole may be located upstream of the first multipole 102, downstream of the second multipole 104, or between the first multipole 102 and the second multipole 104. In some embodiments, each of the generated hexapole fields has the same orientation in the xy-plane in the Larmor reference frame. Alternatively, in other embodiments, one or more of the generated hexapole fields may not have the same orientation in the xy-plane and / or the xy-plane.

[0035] In FIG. 1, the multipole corrector 100 is shown as a box containing multiple optical components (i.e., multipoles and lenses). In various embodiments, these optical components may be encased or partially encased by protective and / or support structures. Furthermore, in embodiments that include such structures, one or more optical components may not be within the structure. FIG. 1 also shows at least one additional primary multipole 120. Individual multipoles of the at least one additional primary multipole 102 may be located upstream of the first primary multipole 102, downstream of the second primary multipole 104, between the first primary multipole 102 and the second primary multipole 104, or combinations thereof.

[0036] 2 shows a collective diagram 200 illustrating the optical behavior of the corrector transfer optics of a prior art corrector and a sixth order corrected STEM multipole corrector system according to the present disclosure. Specifically, diagrams 210 and 230 show the optical behavior to account for the aberrations present in the prior art corrector and the sixth order corrected STEM multipole corrector 100, respectively.

[0037] Drawing 210 shows a first primary hexapole 202 mounted on a second primary hexapole 204. Imaging 2 shows a general scheme of a prior art corrector that is used in a multipole corrector according to the present invention. Each of the drawings 210 and 230 shows the axial rays 206 of the charged particle beam 106 in the xz plane, with the z-axis corresponding to the central axis 108 of the exemplary multipole corrector 100. The drawing 210 shows the axial rays 206 of the charged particle beam 206 as being parallel to the central axis 108 when the charged particle beam 206 enters the entrance face 208 of the first hexapole 202 and as it exits the exit face 210 of the second hexapole 204 ... Imaging 2 further shows that the multipole midplane of the first hexapole 202 is at position 212 and the multipole midplane of the second hexapole 204 is at position 214 as shown.

[0038] Drawing 230 shows both the first primary hexapole 202 and the second primary hexapole 204 in their normal positions (i.e., the first hexapole 202 is positioned over the second hexapole 204 as shown in drawing 230). Imaging FIG. 2 illustrates an embodiment of a sixth-order corrected STEM multipole corrector system in which the first primary hexapole 102, the second primary hexapole 104, or both are mechanically shifted along the central axis 108 from the position where the first primary hexapole 102, the second primary hexapole 104, and the multipole mid-plane of the first primary hexapole 102, are at position 216 and the multipole mid-plane of the second primary hexapole 104, are at position 218. However, as noted above, in other embodiments, only one of the primary multipoles may be shifted. Alternatively, or in addition, as noted above, the shift Δz may also be effectively generated or supplemented by adjusting the transfer lens 118, optionally in combination with excitation changes of one or more optical elements upstream of the sixth-order corrected STEM multipole corrector system, such that the charged particle beam 206 is incident on the first primary hexapole 102 at an angle non-parallel to the central axis 108. In such an embodiment, the first primary hexapole 202, the second primary hexapole 204, or both, may not be mechanically shifted from the conventional primary hexapole positions in conventional practice.

[0039] 2 further illustrates the corrector system of drawing 230 as including a secondary multipole 112 disposed downstream of the second primary hexapole 104. Each of the first hexapole 102, second primary multipole 104, and secondary hexapole 112 are positioned to combine to correct aberrations up to at least the sixth order produced by the sixth order corrector STEM multipole corrector system illustrated in drawing 230, and are each excited by a corresponding excitation.

[0040] FIG. 3 is a diagram of an exemplary charged particle microscope system(s) 300 for inspecting components of a sample 302 including a sixth order corrected STEM multipole corrector system 100 in an optical column according to the present invention. That is, FIG. 3 illustrates a charged particle microscope system(s) 300 including a STEM multipole corrector system 100 including a hexapole as a component multipole. The exemplary charged particle microscope system(s) 300 may include an electron microscope (EM) setup or an electron lithography setup configured to irradiate and / or otherwise bombard the sample 302 with a beam 304 of charged particles (typically an electron beam or an ion beam). In various embodiments, the charged particle microscope system 300 may be or include one or more different types of EM and / or charged particle microscopes such as, but not limited to, a scanning electron microscope (SEM), a scanning transmission electron microscope (STEM), a transmission electron microscope (TEM), a charged particle microscope (CPM), a dual beam microscope system, and the like. Additionally, in some embodiments, a TEM can also operate as a STEM. Figure 3 illustrates an exemplary charged particle microscope system(s) 300 as a STEM system 306.

[0041] The exemplary charged particle microscope system(s) 300 includes a charged particle source 308 (e.g., a thermionic electron source, a Schottky emission source, a field emission source, a liquid metal ion source, a plasma ion source, etc.) that emits a charged particle beam 304 along an emission axis 310 toward an acceleration lens 312. The emission axis 310 is a central axis that runs from the charged particle source 308 along the length of the exemplary charged particle microscope system(s) 300 and through the sample 302.

[0042] The acceleration lens 312 accelerates / decels, focuses, and / or directs the charged particle beam 304 towards the focusing column 314. The focusing column 314 focuses the charged particle beam 304 for incidence on the sample 302. In addition, the focusing column 314 corrects and / or adjusts aberrations (e.g., geometric aberrations, chromatic aberrations) of the charged particle beam 304. In FIG. 3, the focusing column 314 is shown as including a sixth order corrected STEM multipole corrector system 100 according to the present invention, a transfer lens 318, and an objective lens 320. The sixth order corrected STEM multipole corrector system 100 is connected to one another. Imaging 3 includes a first primary multipole 102 and a second primary multipole 104 that are not biased relative to the first and second primary multipole elements 102, 104. The sixth order corrected STEM multipole corrector system 100 is also shown as including a secondary multipole 112 positioned and / or otherwise configured to produce aberrations in combination with other aberrations produced by the first primary multipole 102 and the second primary multipole element 104 to correct three-fold aberrations up to the sixth order. FIG. 3 also illustrates the sixth order corrected STEM multipole corrector system 100 as including an intermediate multipole 116 and a pair of transfer lenses 118.

[0043] The objective lens 320 is an optical element that focuses the charged particle beam 304 to a point on the sample 302. The objective lens 320 may include a monopole lens, a magnetic-electrostatic combination lens, an electrostatic detector objective lens, or another type of objective lens.

[0044] 3 further illustrates the exemplary charged particle microscope system(s) 300 as including a sample holder 322 that holds the sample 302. The exemplary charged particle microscope system(s) 300 are also illustrated as including a detector 334 configured to detect charged particles 336 passing through the sample 302 as a result of the charged particle beam 304 being incident on the sample 302. In addition, the exemplary charged particle microscope system(s) 300 are illustrated as including an astigmatism correction and scanning coil 338 for causing the charged particle beam 304 to scan the surface of the sample 302. For example, by operating the scanning coil 338, the direction of the charged particle beam 304 can be shifted so that it hits a different location on the sample 302. The exemplary charged particle microscope system(s) 300 further includes one or more projection lenses 340 disposed between the sample 302 and the detector 334.

[0045] 3 further illustrates the exemplary charged particle microscope system(s) 300 as optionally including computing device(s) 342. Those skilled in the art will appreciate that the computing device 342 illustrated in FIG. 3 is merely exemplary and is not intended to limit the scope of the present disclosure. Computing systems and devices may include any combination of hardware or software capable of performing the specified functions, including computers, network devices, Internet appliances, PDAs, wireless telephones, controllers, oscilloscopes, amplifiers, etc. Computing device 342 may also be connected to other devices not illustrated, or may instead operate as a stand-alone system.

[0046] Figure 4 illustrates an exemplary charged particle microscope system(s) 400 that includes a sextuple-corrected STEM multipole corrector system 100 having three primary multipoles, where at least one of the primary multipoles is shifted (via physical translation and / or other adjustments described herein) from its conventional position, resulting in the production of significant fourth-order aberrations. That is, Figure 4 illustrates a charged particle microscope system(s) 400 that includes a STEM multipole corrector system 100 that includes a hexapole as a constituent multipole.

[0047] The exemplary charged particle microscope system(s) 400 includes a charged particle source 404 that emits a charged particle beam 406 along an emission axis 408 and toward an acceleration lens 410. The accelerator lens 410 accelerates / decels, focuses, and / or directs the charged particle beam 406 toward a focusing column 412 configured to focus the charged particle beam 406 so that it is incident on a sample 414. Additionally, the focusing column 412 corrects and / or adjusts for aberrations (e.g., geometric aberrations, chromatic aberrations) of the charged particle beam 416.

[0048] In Figure 4, focusing column 412 is shown as including a sixth order corrected STEM multipole corrector system 100 in accordance with the present invention, a transfer lens 416, and an objective lens 418. The sixth order corrected STEM multipole corrector system 100 shown in Figure 4 includes three primary multipoles (i.e., a first primary multipole 420, a second primary multipole 422, and a third primary multipole 424), at least two of which are mutually exclusive. Imaging Specifically, in FIG. 4, the second primary multipole 422 is mounted on the third primary multipole 424. Imaging However, in other embodiments, other pairs of the three primary multipoles are ImagingThe sixth-order correcting STEM multipole corrector system 100 is also shown as including a secondary multipole 426 arranged and / or otherwise configured to produce aberrations in combination with other aberrations produced by the first primary multipole 420, the second primary multipole 422, and the third primary multipole 424 to correct three-fold aberrations up to sixth order. In embodiments in which the three primary hexapoles do not have the same orientation in the Larmor reference frame, the resulting complex aberration coefficient D4 is D 6,cor That is, D4 / D 6,cor =(D 4r +iD 4i ) / (D 6r,cor +iD 6i,cor ) = real value. Imaging 4 also illustrates the sixth order corrected STEM multipole corrector system 100 as including an optional pair of transfer lenses 428 and an optional third order multipole 430. In an embodiment including a third order multipole 430, D 6,cor / D 8,cor is close to a real value, and the primary hexapole D4 is D4 / D 6,cor = real value, the tertiary multipole 430 can be positioned and / or excited to produce an aberration that combines with the cumulative aberrations produced by the other multipoles of the sixth order correcting STEM multipole corrector system 100 to correct eighth order aberrations. Although FIG. 4 shows the transfer lens 416 as being located between the secondary multipole 426 and the tertiary multipole 430, in other embodiments the transfer lens 416 can be positioned between the third primary multipole 424 and the secondary multipole 426 or downstream of the tertiary multipole 430.

[0049] 4 further illustrates the exemplary charged particle microscope system(s) 400 as including a sample holder 432 that holds a sample 414. The exemplary charged particle microscope system(s) 400 are also illustrated as including a detector 434 configured to detect charged particles passing through the sample 414 as a result of the charged particle beam 406 being incident on the sample 414. In addition, the exemplary charged particle microscope system(s) 400 are illustrated as including an astigmatism correction and scanning coil 436 for causing the charged particle beam 406 to scan the surface of the sample 414.

[0050] For example, by operating the scan coil 436, the direction of the charged particle beam 416 can be shifted so that the charged particle beam 416 strikes a different location on the sample 414. The exemplary charged particle microscope system(s) 400 further includes one or more projection lenses 438 disposed between the sample 414 and the detector 434. FIG. 4 further illustrates the exemplary charged particle microscope system(s) 400 as optionally including a computing device(s) 440.

[0051] FIG. 5 shows the optical performance of a conventional corrector system. Imaging 5-8 show the optical performance of a conventional corrector system. FIG. 5 shows both the beam path of an axial ray 502 of a charged particle beam and the beam path of an off-axis ray 504 of a charged particle beam with a crossover at the center of the primary hexapole with the system operating at a particular acceleration voltage. In each of FIGS. 5-8, line 506 indicates the axial magnetic field of the respective system. If line 506 is non-zero, it indicates the presence of a magnetic lens, such as transfer lens 118.

[0052] 6-8 are diagrams of the optical performance of a corrective STEM multipole corrector system according to the present disclosure. FIG. 6 illustrates the optical performance of a corrective STEM multipole corrector system having a tertiary multipole 114 disposed downstream of a secondary multipole 112 to correct eighth order aberrations. FIG. 6 illustrates both the beam path of an axial ray 602 of a charged particle beam and the beam path of an off-axis ray 604 of a charged particle beam with the system operating at a particular acceleration voltage. As can be seen in the resolved image 606 of the first primary multipole 102, the off-axis ray 604 does not intersect the central axis 108 of the system at the multipole mid-plane of the first primary multipole 102. Rather, the off-axis ray 604 intersects the central axis 108 at a displacement of Δz from the multipole mid-plane of the first primary multipole 102. As discussed above, Δz can be caused by a change in excitation of the transfer lens 118, or a combination thereof, based on the displacement of the primary multipole compared to a conventional corrector. Additionally, the lens upstream of the corrector can be adjusted to produce a non-parallel incident beam. In other embodiments, the off-axis ray 604 passes through the central axis 108 at the multipole mid-plane of the second primary multipole 102, but does not pass through the central axis 108 at the multipole mid-plane of the second primary multipole 104.

[0053] Figure 7 shows the primary multipoles Imaging 7 shows the optical performance of a corrected STEM multipole corrector system with the axial ray 702 of a charged particle beam and the off-axis ray 704 of a charged particle beam with the system operating at a particular acceleration voltage.

[0054] As can be seen in the resolved image 706, the second primary multipole 104 in the illustrated embodiment has a length L1 that is different from the length L2 of the conventional multipole 708 in a conventional corrector system. Furthermore, in FIG. 7, the length L2 of the first primary multipole 102 is different from the length L1 of the second primary multipole 104. FIG. 7 illustrates the multipole mid-plane 703 of the second primary multipole 104, which is shifted by Δz from the location of the multipole mid-plane 705 of the conventional multipole 708 in a conventional corrector system. This shift Δz illustrated in FIG. 7 is asymmetric. That is, FIG. 7 illustrates an embodiment in which only one of the primary multipoles is displaced such that the symmetry of the corrector at the mid-plane is abandoned. The values ​​of the shift Δz, the length L1 of the second multipole 104, the location of the secondary multipole 112, the excitation applied to the secondary multipole 112, or a combination thereof, can be adjusted so that high-order aberrations are corrected. For example, if the multipole is a hexapole, the combination of values ​​can be set such that A2=D4=D6=0 (or different optimum value(s)) for the appropriate primary hexapole excitation level.

[0055] In some embodiments, the length of the first primary multipole 102 is shorter than the length L1 of the secondary multipole 104. In such embodiments, the values ​​of the length difference between the first primary multipole 102 and the second primary multipole 104, the shift Δz, the length L1 of the second primary multipole 104, the position of the secondary multipole 112, the excitation applied to the secondary multipole 112, or a combination thereof can be adjusted so that the higher order aberrations are corrected. For example, if the multipole is a hexapole, the combination of values ​​can be set such that A2=D4=D6=D8=0 (or different optimal value(s)) for the appropriate primary hexapole excitation level. That is, the length difference between the first primary multipole 102 and the second primary multipole 104 allows the corrector according to the present disclosure to correct the eighth order aberration D8 without the need for a tertiary multipole 114.

[0056] FIG. 8 illustrates the optical performance of a corrected STEM multipole corrector system with asymmetric ray paths. FIG. 8 illustrates both the beam path of an axial ray 802 of a charged particle beam and the beam path of an off-axis ray 804 of a charged particle beam with the system operating at a particular acceleration voltage. As can be seen in FIG. 8, the path of the axial ray 802 becomes asymmetric as it travels through the corrector due to one or more of the excitation of the lens 118, the shift Δz of the second primary multipole 104, the length of the second primary multipole 104, the excitation applied to the second primary multipole 104, or a combination thereof. These values ​​and the others mentioned above can be adjusted such that A2=D4=D6=0 (or different optimum value(s)) for the appropriate primary hexapole excitation level.

[0057] FIG. 9 illustrates an exemplary multipole corrector system 900 for correcting sixth order aberrations that includes at least a pair of primary multipoles and multiple multipoles positioned downstream of the pair of primary multipoles positioned and / or otherwise configured to produce aberrations that combine to correct sixth order or higher aberrations.

[0058] 9 illustrates a corrector according to the present disclosure that includes a pair of primary multipoles 102 and 104, a secondary multipole 112, and a tertiary multipole 114. As discussed above, by including the tertiary multipole 114, the multipole corrector system 900 provides a multipole corrector system 900 that is configured such that the pair of primary multipoles 102 and 104 are aligned relative to one another. Imaging When the first and second primary multipoles 102 and 104 are aligned with each other, three-lobe aberrations up to the sixth order can be corrected. Imaging If not, the third order multipole 114 allows the multipole corrector system 900 to correct three-lobe aberrations up to the eighth order.

[0059] As noted above, the multipoles may correspond to any of dipoles, quadrupoles, hexapoles, octopoles, etc. For example, if the multipoles 104, 112, and / or 114 correspond to hexapole fields, the methods described herein may be used to design and / or configure a multipole corrector system 900 that cancels (intrinsic and / or parasitic) 3-fold aberrations in any direction up to the sixth order (and in some embodiments up to the sixth order). As another example, if the multipoles correspond to octopole fields, the methods described herein may be used to design and / or configure a multipole corrector system 900 that cancels (intrinsic and / or parasitic) 4-fold aberrations in any direction up to the seventh order.

[0060] In some embodiments, the exemplary multipole corrector system 900 can include additional primary multipoles beyond the pair of primary multipoles 102 and 104. For example, in some embodiments, the exemplary multipole corrector system 900 can include four or six primary multipoles (e.g., a quadrupole octupole corrector). In such embodiments, the second multipole 104 corresponds to the primary multipole closest to the secondary multipole 112.

[0061] Figure 9 shows a charged particle beam 902 being directed onto a sample 904 by an objective lens 906. Figure 9 also shows a transfer lens 910 and an optional transfer lens 908 that allow the microscope system to operate with the objective lens 906 (and the first upstream lens as a probe-forming lens) turned off, for example to study the sample in a magnetic field-free environment, such as in Lorentz microscopy.

[0062] 10 illustrates an exemplary charged particle microscope system(s) 1000 including an exemplary multipole corrector system 900 for correcting sixth-order aberrations. The exemplary charged particle microscope system(s) 1000 illustrated in FIG. 10 is an SEM system 1002 that can operate in a standard mode of operation and a Lorentz mode of operation. That is, the path of the charged particle beam 1004 changes depending on the mode of operation of the exemplary charged particle microscope system(s) 1000.

[0063] The exemplary charged particle microscope system(s) 1000 includes a charged particle source 1008 that emits a charged particle beam 1004 along an emission axis 1010 and toward an acceleration lens 1012 that accelerates / decels, focuses, and / or directs the charged particle beam 1004 toward a focusing column 1014 configured to focus the charged particle beam 1004 for incidence on a sample 1016. The focusing column 1014 is shown as including an exemplary multipole corrector system 900 and an arrangement of multiple lenses 1018. In some embodiments, when the exemplary charged particle microscope system 1000 is operating in Lorentz mode, the objective lens 1020 is turned off. In such embodiments, the Lorentz lens 1022 acts like an objective lens and focuses the charged particle beam 1004 onto the sample 1016.

[0064] 10 further illustrates the exemplary charged particle microscope system(s) 1000 as including a sample holder 1024 for holding a sample 1016. The exemplary charged particle microscope system(s) 1000 are also illustrated as including a detector 1026 configured to detect charged particles emitted and / or reflected by the sample 1016 as a result of the charged particle beam 1004 being incident on the sample 1016. In addition, the exemplary charged particle microscope system(s) 1000 are illustrated as including an astigmatism correction and scanning coil 1028 for causing the charged particle beam 1004 to scan the surface of the sample 1016. FIG. 10 further illustrates the exemplary charged particle microscope system(s) 1000 as optionally including a computing device(s) 1030.

[0065] 11 is a diagram 1100 illustrating how the principal aberrations of the first, second, and secondary multipoles of a sixth-order corrected STEM multipole corrector system are combined in various stages to correct various orders of aberrations. The diagram 1100 shows a first excitation level 1102 applied to each of the first and second primary multipoles 102, 104, a second excitation level 1104 additionally applied to the second primary multipole 104, and a third excitation level 1106 applied to the secondary multipole 112. The diagram 1100 also shows the dominant aberrations 1108 produced by the application of such excitation levels, and relations 1110 of how these aberrations are used to correct second-order three-fold astigmatism.

[0066] The different multipoles of drawing 1110 are placed at different positions in the beam path. These different positions give rise to combined aberrations due to the following effects: The first multipole element M1 changes the direction of the ray by an amount proportional to its dominant aberration m1 in the lowest order. While the ray propagates to the second multipole element M2, this change in direction results in an additional shift dx of the ray at the second multipole element (i.e. in addition to the shift that may already exist due to the convergent or divergent path of the beam). This additional shift dx is proportional to m1 and to the distance d between these two multipole elements (dx~m1d). Due to this dx, the second multipole element causes an additional deflection dx' of the ray (i.e., in addition to what the second multipole element would do in the absence of the first). This additional dx' is proportional to both dx and the dominant aberration m2 of the second multipole element (dx'~m2dx~m1m2d). This addition is called the combined aberration of the multipole elements M1 and M2. It can be classified as a first-order combined aberration because it is produced by the lowest-order effects of M1 and M2. Similarly, the second order effect of the first multipole is the shift of the second multipole (m1d) 2 This produces a secondary combined aberration dx'~m1 2 m2d 2 can be classified as:

[0067] This concept of combined aberrations can be applied not only to combinations of one multipole element with another multipole element, but also to combinations of a set of optical elements (such as a hexapole corrector consisting of two hexapoles and two transfer lenses, the dominant aberration of which is negative spherical aberration) with a multipole element, or to combinations of one set of optical elements with another set of optical elements. In this disclosure, the general term combined aberrations is intended to refer to any first order combined aberrations, second order combined aberrations, third order combined aberrations, etc., and / or combinations thereof.

[0068] Diagram 1100 also shows first order combined aberrations 1112 produced by application of an excitation level, and a relationship 1114 for how the first order combined aberrations are used to correct fourth order triple aberrations. Finally, diagram 1100 also illustrates second order combined aberrations 1116 produced by application of an excitation level, which corrects sixth order three-lobe aberrations of the microscope system when the sixth order corrected STEM multipole corrector system is optimally configured.

[0069] FIG. 12 is a diagram of an exemplary multipole corrector system 1200 for correcting sixth order aberrations including at least a pair of primary multipoles and multiple multipoles positioned downstream of the pair of primary multipoles arranged and / or otherwise configured to generate aberrations that combine to correct sixth order or higher aberrations.

[0070] 12 illustrates a multipole corrector system 1200 according to the present disclosure that includes a triad of primary multipoles 1202 (two of which correspond to primary multipoles 102 and 104), a secondary multipole 112, and an optional tertiary multipole 114. As discussed above, by including the tertiary multipole 114, the multipole corrector system 1200 provides a multipole corrector system that allows the triad of primary multipoles 1202 to be aligned relative to one another. Imaging When the triad of primary multipoles 1202 are aligned with each other, three-lobe aberrations up to the sixth order can be corrected in the sense that they do not generate D4. ImagingIf not, the cubic multipole element 114 allows the multipole corrector system 1200 to correct three-lobe aberrations up to the eighth order. Alternatively, the mutual image condition of the primary multipole element 1202 and the excitation of the secondary multipoles 112 and 114 can be adjusted such that all three-lobe aberrations up to the sixth order are corrected and the second-order off-axis astigmatism is zero.

[0071] 12 further illustrates the multipole corrector system as optionally including a plurality of weak hexapoles 1204 (e.g., weak hexapoles). In some embodiments, the plurality of weak multipoles can include two antisymmetric pairs of weak multipoles to correct for off-axis coma. FIG. 12 further illustrates a charged particle beam 1206 that is directed onto a sample 1208 by an objective lens 1210.

[0072] FIG. 13 is a diagram of an exemplary multipole corrector system 1300 for correcting sixth order aberrations including a pair of primary multipoles, multiple transfer lenses including a weak circular transfer lens, and multiple multipoles positioned downstream of the pair of primary multipoles arranged and / or otherwise configured to generate aberrations that combine to correct sixth order or higher aberrations.

[0073] 13 illustrates a multipole corrector system 1300 according to the present disclosure that includes a triad of transfer lens multipoles 1302 (a central transfer lens corresponding to a weak circular transfer lens), a secondary multipole 112, and an optional tertiary multipole 114. As discussed above, by including the tertiary multipole 114, the multipole corrector system 1300 provides a multipole corrector system that is similar to the multipole corrector system 1300 in that the pair of primary multipoles 102 and 104 are aligned relative to each other. Imaging When the first and second primary multipoles 102 and 104 are aligned with each other, three-lobe aberrations up to the sixth order can be corrected. ImagingIf not, the third order multipole 114 allows the multipole corrector system 1300 to correct three-lobe aberrations up to the eighth order. In some embodiments, the length of the first primary multipole 102 may be different than the length of the second primary multipole 104, such that the first primary multipole 102 and the second primary multipole 104 are closer to each other. Imaging 13 further shows the charged particle beam 106 being directed onto the sample 1304 by an objective lens 1306.

[0074] Figures 14-16 are flat Ronchigram images produced by microscope systems with a conventional corrector system, a 6th order corrected STEM multipole corrector system, and an 8th order corrected STEM multipole corrector system, respectively. A Ronchigram is a projected image (pattern) of a sample formed on a diffraction plane, where a convergent incident electron beam is focused near the sample using a probe-forming lens. The flat Ronchigram is used to explain the corrector performance in a microscope system. Comparing Figures 14 and 15-16, the 6th order corrected STEM multipole corrector system and the 8th order corrected STEM multipole corrector system generate a larger aberration free region (i.e., half angle ~100 mrad) than the conventional corrector system corrected up to 5th order (i.e., less than half angle ~80 mrad).

[0075] Examples of inventive subject matter according to the present disclosure are described in the paragraphs listed below.

[0076] A1. A corrector for correcting axial aberrations in a charged particle system, comprising: a first primary hexapole that generates a first primary hexapole field when a first excitation is applied to the first primary hexapole; a second primary hexapole that generates a second primary hexapole field when a second excitation is applied to the second primary hexapole, the second primary hexapole being disposed between the first primary hexapole and a lens that is a source of spherical aberration when used in a charged particle system, the first primary hexapole being disposed on the second primary hexapole; ImagingThe second primary hexapole, which is not connected to the optics, produces a fourth-order aberration in combination. a secondary hexapole for correcting fourth-order and sixth-order aberrations, the secondary hexapole being positioned between a second primary hexapole and a lens when the corrector is used in a charged particle system.

[0077] A1.0.1. The corrector of paragraph A1, wherein the lens from which the spherical aberration occurs is a particle-optical lens.

[0078] A1.0.2. The corrector of any of paragraphs A1 through A1.0.1, wherein the lens acts as an objective lens when the corrector is used in a charged particle microscope system.

[0079] A1.0.3. A corrector of any of paragraphs A1 to A1.0.2, wherein a lens is the primary source of spherical aberration when the corrector is used in a charged particle microscope system.

[0080] A1.0.4. The corrector of any of paragraphs A1 through A1.0.3, wherein the charged particle system is a charged particle microscope system.

[0081] A1.0.5. The corrector of any of paragraphs A1 through A1.0.4, wherein the charged particle system is an electron microscope system.

[0082] A1.1. The compensator of any of paragraphs A1-A1.0.5, wherein the secondary hexapole is configured to generate a third hexapole field when a third excitation is applied to the secondary hexapole.

[0083] A1.1.1. The corrector of paragraph A1.1, wherein the third hexapole field generates one or more aberrations that correct fourth-order and sixth-order aberrations.

[0084] A1.2. The corrector of any of paragraphs A1-A1.1.1, further comprising a tertiary hexapole for correcting eighth order aberrations, the tertiary hexapole being positioned between the secondary hexapole and the lens when the corrector is used in a charged particle system.

[0085] A1.2.1. The compensator of paragraph A1.2, wherein the tertiary hexapole is configured to generate a fourth hexapole field when a fourth excitation is applied to the tertiary hexapole.

[0086] A1.2.1.1. The corrector of paragraph A1.2.1, wherein the fourth hexapole field generates one or more aberrations that correct eighth-order aberrations.

[0087] A1.2.1.1.1. The corrector of paragraph A1.2.1.1, wherein the fourth hexapole field generates one or more combination aberrations (e.g., first order combination aberrations, second order combination aberrations, etc.) that correct the eighth order aberrations.

[0088] A2. The corrector of any of paragraphs A1 through A1.2.1.1, wherein the secondary hexapole generates second order aberrations that generate primary combined aberrations that correct fourth order aberrations.

[0089] A2.1. The corrector of paragraph A2, wherein the first combination aberration includes or corresponds to a primary combination aberration.

[0090] A2.2. The corrector of paragraph A2, wherein the first combination aberration includes or corresponds to a second order combination aberration.

[0091] A3. The corrector of any of paragraphs A1-A2.2, wherein the secondary hexapole is configured such that, when placed in the optical column of the charged particle microscope, position aberrations caused by drift space between the corrector and the objective lens combine with additional aberrations produced by the secondary hexapole to form a second combined aberration that corrects sixth order aberrations.

[0092] A3.1. The corrector of paragraph A3, wherein the second combination aberration includes or corresponds to a primary combination aberration.

[0093] A3.2. The corrector of paragraph A3, wherein the second combination aberration includes or corresponds to a secondary combination aberration.

[0094] A4. The corrector of any of paragraphs A1-A3.2, wherein the contribution of the first primary hexapole, the contribution of the second primary hexapole, and the contribution of any transfer optics between the first primary hexapole and the second primary hexapole are not canceled.

[0095] A4.1. The corrector of paragraph A4, wherein the first excitation corresponds to an excitation voltage that, when applied to the first primary hexapole, causes the first primary hexapole to generate a first primary hexapole field.

[0096] A4.2. The corrector of paragraph A4, wherein the first excitation corresponds to an excitation current that, when applied to the first primary hexapole, causes the first primary hexapole to generate a first primary hexapole field.

[0097] A4.3. The compensator of any of paragraphs A4 to A4.2, wherein the second excitation is greater than the first excitation.

[0098] A4.4. The corrector of any of paragraphs A4-A4.3, wherein the contribution of the first primary hexapole, the contribution of the second primary hexapole, and the contribution of any transfer optics between the first primary hexapole and the second primary hexapole produce a triple astigmatism A2 and a fourth-order three-lobe aberration D4.

[0099] A5. On the second primary hexapole Imaging The first primary hexapole is not connected to the second primary hexapole. Imaging The compensator of any of paragraphs A1-A4.4, responsive to a first displacement of the first primary hexapole along the axis from a position where the first primary hexapole is aligned.

[0100] A5.1. The compensator of paragraph A5, wherein the first displacement is 0.1 mm, 0.5 mm, 1 mm or more.

[0101] A5.2. The compensator of paragraph A5, wherein the first displacement is greater than or equal to 0.1%, 0.5%, or 1% of the distance between the two primary hexapoles.

[0102] A6. On the second primary hexapole Imaging The first primary hexapole is not connected to the second primary hexapole. Imaging The compensator of any of paragraphs A1-A5.2, responsive to a second displacement of the second primary hexapole along the axis from a position where the first primary hexapole is aligned along the axis.

[0103] A6.1. The compensator of paragraph A6, wherein the second displacement is 0.1 mm, 0.5 mm, 1 mm or more.

[0104] A6.2. The compensator of paragraph A6, wherein the second displacement is greater than or equal to 0.1%, 0.5%, or 1% of the distance between the two primary hexapoles.

[0105] A7. Any of the compensators of paragraphs A6 to A6.2 when dependent on A5 to A5.1, where the first displacement is the same magnitude as the second displacement.

[0106] A8. The compensator of any of paragraphs A6 to A7 when dependent on A5 to A5.1, wherein the first displacement is in an opposite direction to the second displacement.

[0107] A9. On top of the hexapole Imaging The corrector of any of paragraphs A1-A4, wherein the unbiased first primary hexapole corresponds to a beam incident on the first primary hexapole at a non-parallel angle.

[0108] A9.1. On the hexapole Imaging The corrector of paragraph A9, wherein the first primary hexapole not parallel corresponds to a lens excitation of one or more of the lenses upstream of the corrector, and the beam is incident on the first primary hexapole at a non-parallel angle.

[0109] A9.2. The corrector of paragraph A9, wherein a beam incident on the first primary hexapole at a non-parallel angle corresponds to a beam incident on the first primary hexapole at a diverging angle.

[0110] A10. The corrector of any of paragraphs A1-A9.2, further including a set of one or more transfer lenses between the first primary hexapole and the second primary hexapole.

[0111] A11. The compensator of any of paragraphs A1-A9.1, further including a third hexapole disposed between the first primary hexapole and the second primary hexapole.

[0112] A11.1. The corrector of paragraph A1, further including a first set of one or more transfer lenses between the first primary hexapole and the third hexapole, and a second set of one or more transfer lenses between the third hexapole and the second primary hexapole.

[0113] A11.2. The compensator of any of paragraphs A11-A11.1, wherein the third primary hexapole disposed between the first primary hexapole and the second primary hexapole is a third primary hexapole.

[0114] A11.3. The compensator of any of paragraphs A11-A11.2, wherein a third hexapole disposed between the first primary hexapole and the second primary hexapole is a weak intermediate hexapole.

[0115] A12. The compensator of any of paragraphs A1-A12.4, further including a third hexapole disposed upstream of the first primary hexapole.

[0116] A12.1. The corrector of paragraph A2, further including a first set of one or more transfer lenses between the third hexapole and the first primary hexapole, and a second set of one or more transfer lenses between the first primary hexapole and the second primary hexapole.

[0117] A13. The compensator of any of paragraphs A1-A9.1, further including a third hexapole disposed between the second primary hexapole and the secondary hexapole.

[0118] A13.1. The corrector of paragraph A13, further including a first set of one or more transfer lenses between the first primary hexapole and the second primary hexapole, and a second set of one or more transfer lenses between the second primary hexapole and the third hexapole.

[0119] A14. The compensator of any of paragraphs A1-A13.1, wherein the first length of the first primary hexapole is different from the second length of the second primary hexapole.

[0120] A14.1. The amender of paragraph A14, wherein the second length is greater than the first length.

[0121] A15. The compensator of any of paragraphs B1 to B14.1, further comprising one or more additional primary hexapoles.

[0122] A15.1. The corrector of paragraph B15, wherein an additional excitation is applied to at least one of the one or more additional primary hexapoles, resulting in an additional hexapole field that contributes to the combined fourth-order aberration.

[0123] B1. A corrector for correcting axial aberrations in a charged particle system, comprising: a first primary multipole that generates a first primary multipole field when a first excitation is applied to the first primary multipole; a second primary multipole that generates a second primary multipole field when a second excitation is applied to the second primary multipole, and when the corrector is used in the charged particle system, the second primary multipole is disposed between the first primary multipole and a lens that is a source of spherical aberration, and the first primary multipole is disposed on the second primary multipole; Imaging The second primary multipole element, which is not connected to the optical axis, generates a fourth-order aberration in combination. A corrector comprising: a secondary multipole for correcting fourth-order and sixth-order aberrations, the secondary multipole being positioned between a second primary multipole and a lens when the corrector is used in a charged particle system.

[0124] B1.0.1. The corrector of paragraph B1, wherein the lens that is the primary source of spherical aberration is a particle-optical lens.

[0125] B1.0.2. The corrector of any of paragraphs B1-B1.0.1, wherein the lens acts as an objective lens when the corrector is used in a charged particle microscope system.

[0126] B1.0.3. The corrector of any of paragraphs B1 to B1.0.2, wherein a lens is the primary source of spherical aberration when the corrector is used in a charged particle microscope system.

[0127] B1.0.4. The corrector of any of paragraphs B1 through B1.0.3, wherein the charged particle system is a charged particle microscope system.

[0128] B1.0.5. The corrector of any of paragraphs B1 through B1.0.4, wherein the charged particle system is an electron microscope system.

[0129] B1.1. The compensator of any of paragraphs B1-B1.0.1, wherein the secondary multipole is configured to generate a third multipole field when a third excitation is applied to the secondary multipole.

[0130] B1.1.1. The corrector of paragraph B1.1, wherein the third multipole field generates one or more aberrations that correct fourth-order and sixth-order aberrations.

[0131] The corrector of paragraph B1, further comprising a tertiary multipole for correcting 2.8th order aberrations, the tertiary multipole being disposed between the secondary multipole and the lens when the corrector is used in a charged particle system.

[0132] B1.2.1. The compensator of paragraph B1.2, wherein the third-order multipole is configured to generate a fourth multipole field when a fourth excitation is applied to the third-order multipole.

[0133] B1.2.1.1. The corrector of paragraph B1.2.1, wherein the fourth multipole field generates one or more aberrations that correct eighth-order aberrations.

[0134] The corrector of paragraph B1.2.1.1, wherein the fourth hexapole field generates one or more combination aberrations (e.g., first order combination aberrations, second order combination aberrations, etc.) that correct the eighth order aberration.

[0135] B2. The corrector of any of paragraphs B1 through B1.1.1, wherein the second-order multipole generates second-order aberrations that generate 1.1-order combined aberrations that correct fourth-order aberrations.

[0136] B2.1. The corrector of paragraph B2, wherein the first combination aberration includes or corresponds to a primary combination aberration.

[0137] B2.2. The corrector of paragraph B2, wherein the first combination aberration includes or corresponds to a second order combination aberration.

[0138] B3. The corrector of any of paragraphs B1-B2.2, wherein the secondary multipole is configured such that, when placed in the optical column of the charged particle microscope, position aberrations caused by drift space between the corrector and the objective lens combine with additional aberrations produced by the secondary multipole to form a second combined aberration that corrects sixth order aberrations.

[0139] B3.1. The corrector of paragraph B3, wherein the first combination aberration includes or corresponds to a primary combination aberration.

[0140] B3.2. The corrector of paragraph B3, wherein the first combination aberration includes or corresponds to a second order combination aberration.

[0141] B4. The corrector of any of paragraphs B1-B3.2, wherein the contribution of the first primary multipole, the contribution of the second primary multipole, and the contribution of any transfer optics between the first primary multipole and the second primary multipole are not canceled.

[0142] B4.1. The corrector of paragraph B4, wherein the first excitation corresponds to an excitation voltage that, when applied to the first primary multipole, causes the first primary multipole to generate a first primary multipole field.

[0143] B4.2. The corrector of paragraph B4, wherein the first excitation corresponds to an excitation current that, when applied to the first primary multipole, causes the first primary multipole to generate a first primary multipole field.

[0144] B4.3. The compensator of any of paragraphs B4-B4.2, wherein the second excitation is greater than the first excitation.

[0145] B4.4. The corrector of any of paragraphs B4 to B4.3, wherein the contribution of the first primary multipole, the contribution of the second primary multipole, and the contribution of any transfer optics between the first primary multipole and the second primary multipole produce a triple astigmatism A2 and a fourth-order three-lobe aberration D4.

[0146] B5. On the second primary multipole Imaging The first primary multipole is placed on the second primary multipole. Imaging The compensator of any of paragraphs B1-B4.4, responsive to a first displacement of the first primary multipole along the axis from a position where the first primary multipole is positioned.

[0147] B5.1. The compensator of paragraph B5, wherein the first displacement is 0.1 mm, 0.5 mm, 1 mm or more.

[0148] B5.2. The compensator of paragraph B5, wherein the first displacement is greater than or equal to 0.1%, 0.5%, or 1% of the distance between the two primary multipoles.

[0149] B6. On the second primary multipole ImagingThe first primary multipole is placed on the second primary multipole. Imaging The compensator of any of paragraphs B1-B5.2, responsive to a second displacement of the second primary multipole along the axis from a position where the second primary multipole is aligned.

[0150] B6.1. The compensator of paragraph B6, wherein the second displacement is 0.1 mm, 0.5 mm, 1 mm or more.

[0151] B6.2. The compensator of paragraph B6, wherein the first displacement is greater than or equal to 0.1%, 0.5%, or 1% of the distance between the two primary multipoles.

[0152] B7. A compensator of any of paragraphs B6 to B6.2 when dependent on B5 to B5.1, wherein the first displacement is the same magnitude as the second displacement.

[0153] B8. The compensator of any of paragraphs B6-B7, when dependent on B5-B5.1, wherein the first displacement is in an opposite direction to the second displacement.

[0154] B9. On top of multipole Imaging The corrector of any of paragraphs B1-B4, wherein the unbiased first primary multipole corresponds to a beam incident on the first primary multipole at one of a divergence angle or a convergence angle.

[0155] B9.1. On the multipole Imaging The corrector of paragraph B9, wherein the first primary multipole not being biased corresponds to a lens excitation of one or more of the lenses upstream of the corrector, and the beam is incident on the first primary multipole at one of a divergence angle or a convergence angle.

[0156] B9.2. The corrector of paragraph B9, wherein a beam incident on the first primary multipole at a non-parallel angle corresponds to a beam incident on the first primary multipole at a diverging angle.

[0157] B10. The corrector of any of paragraphs B1-B9.1, further including a set of one or more transfer lenses between the first primary multipole and the second primary multipole.

[0158] B11. The compensator of any of paragraphs B1-B9.1, further including a third multipole disposed between the first primary multipole and the second primary multipole.

[0159] B11.1. The corrector of paragraph B1, further including a first set of one or more transfer lenses between the first primary multipole and the third multipole, and a second set of one or more transfer lenses between the third multipole and the second primary multipole.

[0160] B11.2. The compensator of any of paragraphs B11-B11.1, wherein the third primary multipole disposed between the first primary multipole and the second primary multipole is a third primary multipole.

[0161] B11.3. The compensator of any of paragraphs B11-B11.2, wherein a third multipole disposed between the first primary multipole and the second primary multipole is a weak intermediate multipole.

[0162] B12. The corrector of any of paragraphs B1-B11.3, further comprising a third multipole disposed upstream of the first primary multipole.

[0163] B12.1. The corrector of paragraph B2, further including a first set of one or more transfer lenses between the third multipole and the first primary multipole, and a second set of one or more transfer lenses between the first primary multipole and the second primary multipole.

[0164] B13. The compensator of any of paragraphs B1-B9.1, further including a third multipole disposed between the second primary multipole and the secondary multipole.

[0165] B13.1. The corrector of paragraph B13, further including a first set of one or more transfer lenses between the first primary multipole and the second primary multipole, and a second set of one or more transfer lenses between the second primary multipole and the third multipole.

[0166] B14. The compensator of paragraphs B1 to B13.1, wherein the multipole is a hexapole.

[0167] B14. The compensator of any of paragraphs B1-B13.1, wherein the first length of the first primary multipole is different from the second length of the second primary multipole.

[0168] B14.1. The amender of paragraph B14, wherein the second length is greater than the first length.

[0169] B15. The compensator of any of paragraphs B1 to B14.1, further comprising one or more additional primary multipoles.

[0170] B15.1. The corrector of paragraph B15, wherein an additional excitation is applied to at least one of the one or more additional primary multipoles, resulting in an additional multipole field that contributes to the combined fourth-order aberration.

[0171] C1. A corrector for correcting axial aberrations in a charged particle system, comprising: a first primary multipole that generates a first primary multipole field when a first excitation is applied to the first primary multipole; a second primary multipole that generates a second primary multipole field when a second excitation is applied to the second primary multipole, and when the corrector is used in the charged particle system, the second primary multipole is disposed between the first primary multipole and a lens that is a source of spherical aberration, and the first primary multipole is disposed on the second primary multipole; Imaging a second primary multipole, a secondary multipole for generating a third multipole field when a third excitation is applied to the secondary multipole, the secondary multipole being disposed between the second primary multipole and the lens when the corrector is used in a charged particle system; a cubic multipole for generating a fourth multipole field when a fourth excitation is applied to the cubic multipole, the cubic multipole being disposed between the second multipole and a lens when the corrector is used in a charged particle system, the fourth multipole field correcting sixth order aberrations.

[0172] C1.0.1. The corrector of paragraph C1, wherein the lens that is the primary source of spherical aberration is a particle-optical lens.

[0173] The corrector of any of paragraphs C1-C1.0.1, wherein the lens acts as an objective lens when the corrector is used in a charged particle microscope system.

[0174] C1.0.3. The corrector of any of paragraphs C1 to C1.0.2, wherein a lens is the primary source of spherical aberration when the corrector is used in a charged particle microscope system.

[0175] C1.0.4. The corrector of any of paragraphs C1 through C1.0.3, wherein the charged particle system is a charged particle microscope system.

[0176] C1.0.5. The corrector of any of paragraphs C1 through C1.0.4, wherein the charged particle system is an electron microscope system.

[0177] C1.1. The corrector of any of paragraphs C1 to C1.0.1, further comprising a fourth-order multipole for correcting eighth-order aberrations, the fourth-order multipole being positioned between the third-order multipole and the particle-optical lens when the corrector is used in a charged particle microscope system.

[0178] C1.1.1. The compensator of paragraph C1.1, wherein the fourth-order multipole is configured to generate a fifth multipole field when a fifth excitation is applied to the fourth-order multipole.

[0179] C1.1.1.1. The corrector of paragraph C1.1.1, wherein the fifth multipole field generates one or more aberrations that correct eighth-order aberrations.

[0180] The corrector of any of paragraphs C1 through C1.1.1.1, wherein the contribution of the first primary multipole, the contribution of the first primary multipole, and the contribution of any transfer optics between the first primary multipole and the second primary multipole are not cancelled.C2.1.The corrector of paragraph C2, wherein the first excitation corresponds to an excitation voltage that, when applied to the first primary multipole, causes the first primary multipole to generate a first primary multipole field.

[0181] C2.2. The corrector of paragraph C2, wherein the first excitation corresponds to an excitation current that, when applied to the first primary multipole, causes the first primary multipole to generate a first primary multipole field.

[0182] C2.3. The compensator of any of paragraphs C2-C2.2, wherein the second excitation is greater than the first excitation.

[0183] C2.4. The corrector of any of paragraphs C2-C2.3, wherein a contribution of the first primary multipole, a contribution of the second primary multipole, and a contribution of any transfer optics between the first primary multipole and the second primary multipole produce a triple astigmatism A2 and a fourth-order three-lobe aberration D4.

[0184] C3. The corrector of any of paragraphs C1-C2.4, further including a set of one or more transfer lenses between the first primary multipole and the second primary multipole.

[0185] C4. The compensator of any of paragraphs C1-C3, further including a third multipole disposed between the first primary multipole and the second primary multipole.

[0186] C5. The corrector of paragraphs C1 to C5, wherein the multipole is a hexapole.

[0187] C6. The compensator of any of paragraphs C1-C5, wherein the first length of the first primary multipole is different from the second length of the second primary multipole.

[0188] C6.1. The corrector of paragraph C6, wherein the second length is greater than the first length.

[0189] D1. A charged particle microscope comprising: a charged particle source configured to emit a charged particle beam toward a sample; and an optical column configured to focus the charged particle beam on the sample, the optical column including a corrector of any of paragraphs A1-A13.1, B1-B14, or C1-C5.

[0190] E1. Use of any of the correctors of paragraphs A1-A13.1, B1-B14, or C1-C5.

[0191] F1. Use of the charged particle microscope of paragraph D1.

Claims

1. 1. A corrector for correcting sixth or higher order axial aberrations in a charged particle system, the corrector being provided in an optical column of the charged particle system, the corrector comprising: a first primary multipole that generates a first primary multipole field when a first excitation is applied to the first primary multipole; a second primary multipole that generates a second primary multipole field when a second excitation is applied to the second primary multipole, and when used in the charged particle system, the second primary multipole is disposed between the first primary multipole and a lens of the charged particle system that is a source of spherical aberration, and the first primary multipole is not imaged onto the second primary multipole such that a combined fourth order aberration is generated; a secondary multipole for correcting the fourth and sixth order aberrations, the secondary multipole being disposed between the second primary multipole and the lens when used in the charged particle system; The secondary multipole element is when a third excitation is applied to the secondary multipole, the secondary multipole generates a third multipole field; a corrector, wherein the third multipole field is configured to generate one or more aberrations that correct the fourth order aberrations and the sixth order aberrations.

2. The corrector of claim 1 , wherein the secondary multipole element is further configured to correct three-fold astigmatism A2.

3. The corrector of claim 1 , wherein the second-order multipole element generates second-order aberrations that generate a combined aberration that corrects the fourth-order aberration.

4. 2. The corrector of claim 1, wherein the first excitation and the second excitation are such that a first contribution to the triple astigmatism A2 generated by the first primary multipole field and a second contribution to the triple astigmatism A2 generated by the second primary multipole field do not cancel each other out.

5. 2. The corrector of claim 1, wherein the first primary multipole that is not imaged onto the second primary multipole includes a charged particle beam that is incident on the first primary multipole at one of a diverging angle or a converging angle when the corrector is in use.

6. 2. The corrector of claim 1, wherein the first primary multipole that is not imaged onto the second primary multipole includes a lens excitation of one or more of the lenses upstream of the corrector such that a charged particle beam is incident on the first primary multipole at one of a diverging angle or a converging angle when the corrector is in use.

7. The corrector of claim 1 , wherein the first primary multipole that is not imaged onto the second primary multipole corresponds to a lens excitation of one or more of lenses disposed between the first primary multipole and the second primary multipole.

8. The corrector of claim 1 , wherein the first primary multipole and the second primary multipole are each a hexapole.

9. 9. The corrector according to claim 1, further comprising a cubic multipole for correcting eighth order aberrations, the cubic multipole being positioned between the secondary multipole and the lens when used in the charged particle system.

10. The third-order multipole element is a fourth multipole field is generated when a fourth excitation is applied to the third multipole; The corrector of claim 9 , wherein the fourth multipole field is configured to generate one or more aberrations that correct the eighth order aberration.

11. A corrector as described in any one of claims 1 to 10, wherein one of the first primary multipole or the second primary multipole is displaced by a first displacement along a central axis from a position where the first primary multipole is imaged on the second primary multipole so that the first primary multipole is not imaged on the second primary multipole.

12. The corrector of claim 11, wherein the other of the first primary multipole or the second primary multipole is displaced by a second displacement along the central axis from a position where the first primary multipole is imaged on the second primary multipole, such that the first primary multipole is not imaged on the second primary multipole.

13. The corrector of claim 12 , wherein the first displacement is in an opposite direction to the second displacement.

14. a charged particle source configured to emit a charged particle beam toward the sample; and an optical column configured to focus the charged particle beam on the sample, the optical column comprising the corrector according to any one of claims 1 to 13 for correcting axial aberrations of lenses that are a source of spherical aberration.

Images