Proximity electrode, charged particle beam device and method for inspecting and / or imaging a sample

Abstract

There is provided a proximity electrode for a charged particle beam device, the proximity electrode comprising a body having an aperture within the body, and the body having a plurality of projections radially overhanging into the aperture, and the aperture and the projections having n-fold rotational symmetry, where n is an integer.

Description

Technical Field

[0001] The present disclosure relates to a proximity-electrode for a charged particle beam device, a charged particle beam device for at least one of imaging and inspecting a sample, and a method for at least one of inspecting and imaging a sample using a charged particle beam device, in particular, a charged particle beam device for at least one of imaging and inspecting a sample, the charged particle beam device having a proximity-electrode, and to a method for at least one of inspecting and imaging a sample using a charged particle beam device having a proximity-electrode. Background Art

[0002] Charged particle beam equipment has many applications in a variety of industrial fields, including but not limited to critical dimension setting of semiconductor devices during manufacturing, defect review of semiconductor devices, inspection of semiconductor devices, exposure systems for lithography, detection equipment and test systems. There is a particularly high demand for high-performance charged particle beam equipment for structuring, testing and inspection of samples or specimens on the micrometer and nanometer scale.

[0003] Micrometer and nanometer scale process control, inspection and structuring are usually done with charged particle beams (especially electron beams), which are generated and focused in charged particle beam equipment (such as scanning electron microscopes). Due to their shorter wavelength, charged particle beams provide superior spatial resolution compared to photon beams, for example.

[0004] Sample inspection and imaging generally involves detecting interaction particles and interaction radiation generated when a primary charged particle beam is incident on a sample. Interaction particles are, for example, secondary charged particles and backscattered charged particles, particularly secondary electrons and backscattered electrons. Interaction radiation includes X-rays and cathodoluminescence light.

[0005] Document US2017 / 047192A1 describes a system with an electrode comprising a first opening for a primary charged particle beam to pass through and one or more second openings for off-axis backscattered particles to pass through. The electrode is the electrode closest to the sample in a charged particle beam device.

[0006] In view of the influence of electrodes on the passage of primary charged particles and signal particles, it is considered desirable to improve the electrodes and the corresponding charged particle beam devices and methods of operating the corresponding charged particle beam devices in order to meet the current demand for high-performance charged particle beam devices for structuring, testing and inspecting samples or specimens at the micrometer and nanometer scales. Summary of the invention

[0007] The purpose of the present disclosure is to meet the current need for improvements in the prior art. In view of this, the following describes a proximity electrode for a charged particle beam device, a charged particle beam device for at least one of imaging and inspecting a sample with a proximity electrode, and a method for at least one of inspecting and imaging a sample with a charged particle beam device, in particular a method for at least one of inspecting and imaging a sample with a charged particle beam device with a proximity electrode.

[0008] According to one aspect, a proximity electrode for a charged particle beam apparatus includes a body having a hole therein and a plurality of protrusions radially depending into the hole, the hole and protrusions having n-fold rotational symmetry, n being an integer.

[0009] According to one aspect, a charged particle beam device for at least one of imaging and inspecting a sample is provided. According to this aspect, the charged particle beam device comprises: a beam emitter for emitting a primary charged particle beam; and a deceleration field device for decelerating the primary charged particle beam before the primary charged particle beam is incident on the sample, the deceleration field device comprising an objective lens and a proximity electrode arranged downstream of a principal plane of the objective lens; wherein the charged particle beam device is adapted to guide the primary charged particle beam to the sample along an optical axis to generate signal charged particles from the sample.

[0010] According to one aspect, a method of at least one of imaging and inspecting a sample using a charged particle beam device having a proximity electrode is provided.

[0011] Other aspects, embodiments, examples, features and advantages of the method may be understood from the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to further understand the above aspects of the present disclosure, a more detailed description will be provided below with reference to the accompanying drawings, which include:

[0013] Figure 1 A proximity electrode is shown, which is not covered by the claims, has neither a protrusion nor a bulbous end, and which is helpful in understanding the present invention;

[0014] Figure 2 shows a proximity electrode according to embodiments and examples described herein, the proximity electrode comprising a protrusion without a bulbous end, the protrusion cantilevering into a hole;

[0015] Figure 3 shows a proximity electrode including a protrusion having a bulbous end and cantilevering into a hole according to embodiments and examples described herein;

[0016] Figure 4 shows a proximity electrode including a bulbous end and cantilevering into a hole according to embodiments and examples described herein;

[0017] Figure 5 shows a proximity electrode including a protrusion without a bulbous end and cantilevering into a hole according to embodiments and examples described herein;

[0018] Figure 6 shows a proximity electrode including a protrusion having a bulbous end and cantilevering into a hole according to embodiments and examples described herein;

[0019] Figure 7 shows a proximity electrode according to various aspects, embodiments and examples described herein;

[0020] Figure 8 A retarding field device including a proximity electrode is shown according to embodiments and examples described herein;

[0021] Fig. 9 A charged particle beam apparatus including a proximity electrode according to various aspects, embodiments and examples described herein is shown;

[0022] Fig.10 shows beam spot size performance according to embodiments and examples described herein; and

[0023] Fig.11 Methods of imaging and / or inspecting a sample according to various aspects, embodiments and examples described herein are shown. Specific embodiments

[0024] Reference will now be made in detail to various aspects, embodiments, examples, one or more of which are further shown or depicted in the accompanying drawings. In the following description, the same reference numerals refer to the same parts. Generally, only the differences with respect to individual embodiments are described. Each aspect, embodiment and example are provided by way of explanation and are not meant to be limiting. In addition, features depicted or described as part of one embodiment may be used on other embodiments or used in combination with other embodiments to produce yet further embodiments. The present disclosure is intended to include such modifications and variations.

[0025] As used herein, "proximity electrode" may be understood as an electrode disposed near the sample, particularly between the objective lens and the sample (or sample stage). In particular, the proximity electrode may be understood as being disposed downstream of the objective lens in the propagation direction of the primary charged particle beam. It may be understood that the proximity electrode is the last electrode or the last element that affects the primary charged particle beam, and / or the proximity electrode is the last electrode or the last element that the primary charged particle beam passes through before being incident on the sample.

[0026] Embodiments of the present disclosure relate to proximity electrodes with large apertures. This enables more signal charged particles to pass through the proximity electrodes. In example applications such as imaging high aspect ratio features and / or collecting large angle fast backscattered charged particles, proximity electrodes with large apertures increase the angle at which signal charged particles are collected. By increasing the number and / or angle of signal charged particle collection, imaging and inspection can be improved. In particular, signal-to-noise ratio, acquisition time, and / or contrast can be improved.

[0027] Embodiments of the present disclosure provide proximity electrodes having one or more of the following benefits: large apertures, low field penetration through the proximity electrode, minimal shadowing effects, and minimal surface electric fields.

[0028] According to one aspect, the proximity electrode comprises a body having a hole in the body, wherein the body comprises a plurality of protrusions radially overhanging into the hole, wherein the hole and / or the protrusions have n-fold rotational symmetry, n being an integer. According to the embodiments and examples described herein, the proximity electrode can be understood to be adapted for use in a charged particle beam device.

[0029] The present disclosure relates to improved proximity electrodes, in particular to improved aperture designs. The improved proximity electrodes are particularly beneficial for charged particle beam devices, such as scanning electron microscopes. The present disclosure also relates to improved charged particle beam devices comprising a proximity electrode as described herein.

[0030] The proximity electrodes according to embodiments of the present disclosure allow for increased areas of signal electron intrusion, ie, reduced shadowing, which can be beneficial for imaging and inspecting samples. In addition, the extraction field strength can be controlled without excessively increasing the magnitude of the voltage applied to the proximity electrode.

[0031] In general, circular holes are often used for approach electrodes. By adapting the geometry of the hole, such as adding a protrusion, the hole can be beneficially enlarged, thereby allowing more signal charged particles and / or signal charged particles at a wider angle to pass through the approach electrode and be collected / detected without undesirably increasing field penetration from the upper column. As described in further detail herein, the geometry and / or number of protrusions can provide varying degrees of reduction in field penetration.

[0032] The protrusion may be understood as protruding from the inwardly facing side of the proximity electrode body toward the center of the aperture without covering or overlapping the center or central region of the aperture. Thus, allowing the central portion through which the primary charged particle beam passes to avoid the protrusion effectively provides a high performance primary charged particle beam, specifically a primary beam spot size comparable to the primary beam spot size when using a proximity electrode without an enlarged aperture and without a protrusion. In other words, the benefits of the improved proximity electrode as described herein may be achieved without compromising the primary charged particle beam, particularly the primary beam spot size.

[0033] The central circle may be understood as a central portion or a part of the aperture, or a central opening, arranged or configured to allow the primary charged particle beam to pass through unhindered.

[0034] According to an embodiment that can be combined with other aspects and embodiments, the central circle in the plane of the hole of the proximity electrode avoids the protrusions, preferably, the radius of the circle extends upward to the end of one or more protrusions. Advantageously, the primary charged particle beam can pass through the proximity electrode without excessive distortion, and the primary beam spot size is good.

[0035] According to an embodiment, which can be combined with other aspects and embodiments, the diameter of the central circle (of the proximity electrode's hole) is at least twice the height of the space separating the proximity electrode 140 from the sample 150 or the sample stage. Advantageously, a large number of signal charged particles can pass through the proximity electrode.

[0036] According to an embodiment that can be combined with other aspects and embodiments, the diameter of the center circle of the proximity electrode 140 is at least twice the distance between the proximity electrode 140 and the sample 150 or the sample stage or at least twice the height of the space between the proximity electrode 140 and the sample 150 or the sample stage. In an example, the width or diameter of the center circle (of the hole of the proximity electrode), the center portion or the center opening is (approximately) at least twice the distance between the proximity electrode 140 and the sample 150 or the sample stage or at least twice the working distance of the charged particle beam device.

[0037] According to an embodiment, all areas of the hole, in particular the area within the central circle and the area outside the central circle, are connected to one another, in particular in the plane of the hole.

[0038] Beneficially, the protrusions extend in a radial orientation, particularly for operation of the proximity electrode.A proximity electrode with radially overhanging protrusions minimizes structures and materials that impede the passage of signal charged particles emanating from the sample and travelling towards the detector.

[0039] In particular, by avoiding structures and materials having a circumferential extension but no radial extension, such as an inner ring element within a bore, and by providing protrusions that cantilever substantially or completely in the radial direction, shadowing effects, in particular in the radial direction, may be minimized.

[0040] According to an embodiment, one or more of the projections, in particular all of the projections, are perpendicular to the optical axis, in particular the axis of the charged particle beam device, close to the electrode and / or the primary charged particle beam overhang. Beneficially, the projections perpendicular to the optical axis, close to the electrode's axis and / or the primary charged particle beam overhang can achieve a shorter working distance and minimal shadow.

[0041] Advantageously, very high voltages and / or surface electric fields are avoided, at least to reduce the need for controls, power supplies and / or reduce the risk of arcing. For the same extraction field strength, adding protrusions allows lower voltages and less intense surface electric fields.

[0042] This is particularly beneficial when one or more ends or one or more tips of the protrusions extend sufficiently radially (e.g. the length of each protrusion is at least 5% of the radius of the hole) and / or reach closer to the center of the hole or closer to each other (e.g. the length of each protrusion is at most 80% of the radius of the hole).

[0043] Embodiments of the present disclosure provide rounded edges, such as beveled edges, having a large convex radius, a minimum convex radius, a minimum radius of curvature and / or a minimum radius of the protrusion, particularly at one or more ends or one or more tips of the protrusion, specifically at one or more ends or one or more tips closest to the center or center area of ​​the hole.

[0044] For example, one or more ends or one or more tips of the protrusion have a bulbous, flared, spherical or rounded shape and / or have a larger width, radius or radius of curvature than the middle or non-end / tip portions of the protrusion.

[0045] According to embodiments, which can be combined with other embodiments described herein, each protrusion has a minimum radius of curvature at a tip portion or an end portion of the protrusion that is larger than a minimum radius of curvature at a middle portion of the protrusion.

[0046] According to an embodiment, which can be combined with other embodiments described herein, the minimum radius of curvature of each of the protrusions is greater than 5%, preferably greater than 10%, and most preferably greater than 20% of the width or diameter of the corresponding protrusion. Beneficially, a minimum peak surface electric field is achieved.

[0047] According to an embodiment that can be combined with other embodiments described herein, the minimum radius of curvature of each of the protrusions in a plane perpendicular to the plane of the proximity electrode and / or the plane of the hole of the proximity electrode exceeds or is larger than the minimum radius of curvature of the corresponding protrusion in the plane of the proximity electrode and / or in the plane of the hole of the proximity electrode.

[0048] The plane approaching the electrode may be understood as the symmetry plane of the approaching electrode or the plane bisecting the approaching electrode (all of the protrusions of the protrusions) or the plane perpendicular to the symmetry axis of the approaching electrode or the plane perpendicular to the central axis of the approaching electrode or the plane perpendicular to the symmetry axis of the hole of the approaching electrode or the plane perpendicular to the optical axis.

[0049] The plane of the hole close to the electrode can be understood as the symmetry plane of the hole close to the electrode or the plane that bisects the hole close to the electrode or the plane perpendicular to the symmetry axis of the hole close to the electrode or the plane perpendicular to the central axis of the hole close to the electrode or the plane perpendicular to the symmetry axis of the hole close to the electrode or the plane perpendicular to the optical axis.

[0050] According to an embodiment that can be combined with other embodiments described herein, the minimum radius of curvature of each of the protrusions in an upward direction and / or in a direction away from the sample and / or sample stage and / or in a direction toward the primary charged particle beam source and / or on the upstream side of the proximity electrode (according to the propagation direction of the primary charged particle beam) exceeds or is larger than the minimum radius of curvature of the corresponding protrusion in a plane close to the electrode and / or in a plane of the hole close to the electrode.

[0051] According to an embodiment that can be combined with other embodiments described herein, the minimum radius of curvature of each of the protrusions in an upward direction and / or in a direction away from the sample and / or sample stage and / or in a direction toward the primary charged particle beam source and / or on the upstream side close to the electrode (according to the propagation direction of the primary charged particle beam) exceeds or is larger than the minimum radius of curvature of the corresponding protrusion in a downward direction and / or in a direction toward the sample and / or sample stage and / or in a direction away from the primary charged particle beam source and / or on the downstream side close to the electrode (according to the propagation direction of the primary charged particle beam).

[0052] Beneficially, the peak surface electric field in a plane perpendicular to the planar approach electrode is minimized, particularly in an upward direction or towards a charged particle beam source where field strength is critical. Beneficially, a more rounded edge may be provided where field strength is most critical.

[0053] According to an embodiment, the protrusion has a minimum radius of curvature so that the peak surface electric field or the maximum magnitude of the surface electric field on the protrusion is at most 3 times or less than 3 times the peak surface electric field or the maximum magnitude of the surface electric field on the body near the electrode or on the non-protrusion portion or non-protrusion portion near the electrode.

[0054] According to an embodiment, each protrusion has a minimum radius of curvature which is at least half the width of the protrusion.

[0055] In a particular embodiment, the minimum radius of curvature at the free end or tip of each protrusion is equal to or greater than half the width at the middle or shaft portion of the respective protrusion.

[0056] In a particular embodiment, the minimum radius of curvature of each protrusion at the free end or tip of the corresponding protrusion is equal to or greater than half the width of the corresponding protrusion at the middle or shaft portion of the corresponding protrusion.

[0057] Beneficially, the peak surface electric field is substantially minimized and the risk of arcing is substantially reduced.

[0058] The table below shows some parameters of different proximity electrode designs. For a specific extraction field, the values ​​of peak surface electric field intensity, aperture size, and proximity electrode operating voltage (related to field penetration; where the design allows a higher degree of field penetration, a higher voltage is required to achieve the same extraction field) are compared for different proximity electrode designs.

[0059]

[0060] Table 1

[0061] like Figure 1 As indicated by the associated entries in Table 1, a baseline proximity electrode design with no enlarged aperture and no protrusions is used below to compare proximity electrode designs with varying degrees of aperture enlargement and varying degrees of protrusions and different protrusion designs.

[0062] Figure 1 The proximity electrode shown is referred to herein as the baseline design. As shown, the proximity electrode 140 has a body 300 with a hole 340 in the body 300. The proximity electrode 140 according to the baseline design includes a (non-enlarged) hole 340 with a radius of approximately 2.3 mm and no protrusions.

[0063] Figure 2 The proximity electrode in is referred to herein as a first design, and as illustrated by the various aspects and embodiments described herein, the first design is provided as an example for illustrating features that may be provided individually / separately or in combination with other features.

[0064] like Figure 2 As shown, the proximity electrode 140 has a body 300 with a hole 340 therein. The proximity electrode 140 according to the first design includes an (enlarged) hole 340 having a radius of approximately 3.2 mm and a protrusion 310. As shown, the protrusion 310 radially overhangs into the hole 340.

[0065] like Figure 2As shown, the protrusion 310 is approximately 1 mm long, which may be understood as being less than half the distance toward the center of the hole or having an overhang length that is less than half the radius of the hole.

[0066] Compared to the baseline design, the proximity electrode according to the first design has a substantially improved aperture size (almost doubled) while the proximity electrode voltage is within the same order of magnitude despite an increase in the peak surface electric field.

[0067] Thus, comparison of the first design with the baseline design shows that by providing the protrusion 310, the clear aperture size can be significantly improved without a substantial impact on the proximity electrode voltage because the protrusion mitigates the increase in field penetration from the enlarged aperture.

[0068] Figure 3 The proximity electrode in is referred to herein as a second design, which is provided as an example for illustrating features that may be provided individually / separately or in combination with other features, as illustrated in the various aspects and embodiments described herein.

[0069] like Figure 3 As shown, the proximity electrode 140 has a body 300 with a hole 340 therein. The proximity electrode 140 according to the second design includes an (enlarged) hole 340 having a radius of approximately 3.2 mm and a protrusion 310. As shown, the protrusion 310 radially overhangs into the hole 340.

[0070] like Figure 3 As shown, the protrusion 310 is about 1.6 mm long, which can be understood as overhanging less than half the distance toward the center of the hole 340 or having an overhang length less than half the radius of the hole 340. The protrusion 310 has a bulbous end 330, which can be understood as an end having an increased radius (in this example, increased by about 50%) relative to the radius at the middle or shaft 320 of the corresponding protrusion 310.

[0071] Compared to the baseline design, the proximity electrode according to the second design has a substantially improved aperture size (similarly improved as the first design) and a beneficially reduced proximity electrode voltage (almost a double improvement for the second design relative to the first design), while the peak surface electric field is within the same order of magnitude (greatly improved relative to the first design).

[0072] Therefore, comparison of the second design with the baseline design shows that by providing a protrusion 310 having a bulbous end 330 (the bulbous end can be understood as an end having a radius that is increased relative to the radius at the middle or rod-shaped portion 320 of the corresponding protrusion 310), the light-through hole size and the electrode voltage close to the electrode can be improved simultaneously without substantially increasing the peak surface electric field.

[0073] Figure 4 The proximity electrode in is referred to herein as a third design, which is provided as an example for illustrating features that may be provided individually / separately or in combination with other features, as illustrated in the various aspects and embodiments described herein.

[0074] like Figure 4 As shown, the proximity electrode 140 has a body 300 with a hole 340 therein. The proximity electrode 140 according to the third design includes an (enlarged) hole 340 having a radius of approximately 3.2 mm and a protrusion 310. As shown, the protrusion 310 radially overhangs into the hole 340.

[0075] like Figure 4 As shown, the protrusion 310 is about 1.6 mm long, which can be understood as overhanging about half the distance toward the center of the hole 340 or having an overhang length of about half the radius of the hole 340. The protrusion 310 has a double bulbous end 330, which can be understood as an end having a radius that is doubled (in this example, increased by about 100%) relative to the radius at the middle or shaft portion 320 of the corresponding protrusion.

[0076] Compared to the baseline design, the proximity electrode according to the third design has a substantially improved aperture size (improved similarly to the first and second designs), a beneficially reduced proximity electrode voltage (improved relative to the second design), while the peak surface electric field is within the same order of magnitude (improved relative to the first and second designs).

[0077] Therefore, comparison of the third design with the baseline design shows that by providing a protrusion 310 with a double bulbous end (an end having a radius at least twice the radius at the middle or rod-shaped portion 320 of the corresponding protrusion 310), the light-clearance size and the proximity electrode voltage can be improved simultaneously while the peak surface electric field remains relatively unchanged.

[0078] Figure 5 The proximity electrode in is referred to herein as a fourth design, which is provided as an example for illustrating features that may be provided individually / separately or in combination with other features, as illustrated by the various aspects and embodiments described herein.

[0079] like Figure 5 As shown, the proximity electrode 140 has a body 300 with a hole 340 therein. The proximity electrode 140 according to the third design includes an (enlarged) hole 340 having a radius of approximately 3.2 mm and a protrusion 310. As shown, the protrusion 310 radially overhangs into the hole 340.

[0080] like Figure 5As shown, the protrusion 310 is approximately 2.2 mm long, which may be understood as overhanging more than half toward the center of the hole 340 or having an overhang length of more than half the radius of the hole 340 .

[0081] Compared to the baseline design, the proximity electrode according to the fourth design has a substantially improved light-through hole size (similarly improved to the first design, the second design, and the third design), a substantially improved proximity electrode voltage (an order of magnitude better than the first design, the second design, and the third design), while the peak surface electric field is within the same order of magnitude (similar to the second design and the third design).

[0082] Therefore, comparison of the fourth design with the baseline design shows that by providing a protrusion that overhangs more than half the distance toward the center of the hole or having an overhang length that exceeds half the radius of the hole, the clear hole size and the approach electrode voltage can be greatly improved without significantly changing the peak surface electric field.

[0083] Figure 6 The proximity electrode in is referred to herein as a fifth design, which is provided as an example for illustrating features that may be provided individually / separately or in combination with other features, as illustrated in the various aspects and embodiments described herein.

[0084] like Figure 6 As shown, the proximity electrode 140 has a body 300 with a hole 340 therein. The proximity electrode 140 according to the fifth design includes an (enlarged) hole 340 having a radius of approximately 3.2 mm and a protrusion 310. As shown, the protrusion 310 radially overhangs into the hole 340.

[0085] like Figure 6 As shown, the protrusion 310 is about 2.2 mm long, which can be understood as overhanging more than half the distance toward the center of the hole 340 or having an overhang length that is more than half the radius of the hole 340. The protrusion 310 has a bulbous end 330, which can be understood as an end having an increased radius (in this example, increased by about 50%) relative to the radius at the middle or shaft portion 320 of the corresponding protrusion.

[0086] Compared to the baseline design, the proximity electrode according to the fifth design not only has a substantially improved light-through hole size (improved similarly to the first design, the second design, the third design and the fourth design) and a substantially improved proximity electrode voltage (improved similarly to the fourth design), but even has an improved peak surface electric field.

[0087] Therefore, comparison of the fifth design with the baseline design shows that by providing an overhang toward the center of the hole that is more than half the distance or has an overhang length that is more than half the radius of the hole, and having a bulbous end 330 (an end having a radius that is increased relative to the radius at the middle of the corresponding protrusion 310 or the rod-shaped portion 320), all of the light-through hole size, the proximity electrode voltage, and the peak surface electric field, in particular the light-through hole size and the proximity electrode voltage, can be improved.

[0088] Other aspects, embodiments, and examples of proximity electrodes are described below.

[0089] Figure 7 Proximity electrodes are shown according to various aspects and embodiments described herein.

[0090] According to one aspect, a proximity electrode 140 for a charged particle beam device includes a body 300 having a hole 340 therein; and the body has a plurality of protrusions 310 radially overhanging into the hole 340, the hole 340 and the protrusions 310 having n-fold rotational symmetry, n being an integer.

[0091] Beneficially, a proximity electrode is provided having a large clear aperture size, low field penetration through the proximity electrode, thereby providing low proximity electrode voltage and minimal shadowing.

[0092] According to an embodiment that can be combined with other embodiments, the protrusion 310 has a minimum curvature radius so that the maximum magnitude of the surface electric field on the protrusion 310 is less than 3 times the maximum magnitude of the surface electric field on the body 300 close to the electrode 140 .

[0093] According to embodiments, which can be combined with other embodiments, each protrusion 310 has a minimum radius of curvature that is at least half of the width of the protrusion 310 .

[0094] Beneficially, the edges are rounded and a proximity electrode is obtained with low field penetration through the proximity electrode, thereby achieving a low proximity electrode voltage and a reduced peak surface electric field.

[0095] According to embodiments that can be combined with other embodiments, the tip or end portion 330 of each protrusion 310 has a minimum radius of curvature that is at least equal to, and preferably greater than, the minimum radius of curvature at the middle or shaft portion 320 of the respective protrusion 310 .

[0096] Advantageously, the protrusion tips are particularly rounded and provide a proximity electrode with a reduced peak surface electric field and, further, provide a low field penetration through the proximity electrode, thereby providing a low proximity electrode voltage.

[0097] According to embodiments, which can be combined with other embodiments, the length of each protrusion 310 is at least 5% of the radius of the hole 340 and at most 80% of the radius of the hole 340 .

[0098] According to embodiments that may be combined with other embodiments described herein, the length of each protrusion 310 is at least 5% of the radius of the hole 340 and / or at most 80% of the radius of the hole (in the plane of the hole or perpendicular to the axis approaching the electrode 140, the optical axis of the charged particle beam device and / or the axis of the primary charged particle beam).

[0099] According to embodiments that may be combined with other embodiments described herein, the length of each protrusion 310 is greater than 50% and / or less than 80% of the radius of the hole 340 (in the plane of the hole 340 or perpendicular to the axis approaching the electrode 140, the optical axis of the charged particle beam device and / or the axis of the primary charged particle beam).

[0100] Beneficially, low field penetration is provided, which is particularly beneficial when provided in combination with a large aperture. In addition, providing a protrusion length that extends substantially into the aperture without contacting each other and without distorting the primary charged particle beam beneficially enables the proximity electrode to have a large clear aperture size, with a minimum field through the proximity electrode, a minimum proximity electrode voltage, and a minimum peak surface electric field.

[0101] It will be appreciated that the tip or end 330 of each protrusion 310 is unsupported, free and / or not in contact or connected to (any portion of) the body 300 of the proximate electrode 140 or another protrusion 310 proximate the electrode 140 .

[0102] It will be appreciated that the length of each protrusion 310 is the length in the direction of the axis of the protrusion 310, in the plane of the hole 340, in the direction perpendicular to the axis of the proximity electrode 140 and / or in the direction perpendicular to the optical axis of the charged particle beam device.

[0103] According to embodiments that can be combined with other embodiments, the radius of the hole 340 is at least 1.5 mm and / or at most 5.5 mm, preferably at least 2 mm and / or at most 5 mm, more preferably at least 2.5 mm and / or at most 4.5 mm, or most preferably at least 3 mm and / or at most 4 mm.

[0104] According to embodiments which can be combined with other embodiments, the hole size, clear hole size or clear area of ​​the hole 340 in the plane of the hole 340 is at least 10 mm 2 and / or up to 95 mm 2 , preferably at least 15 mm 2 and / or up to 80 mm 2 , more preferably at least 20 mm 2and / or up to 65 mm 2 , or most preferably at least 25 mm 2 and / or up to 50 mm 2 .

[0105] Advantageously, the aperture has a large clear aperture size, which is particularly beneficial when provided in combination with the protrusion and embodiments of the protrusion.

[0106] According to an embodiment that can be combined with other embodiments, the proximity electrode 140 is aligned with at least one detector (in particular, a backscattered electron detector, i.e., a BSE detector 134, and / or an energy dispersive X-ray spectroscopy detector, i.e., an EDX detector), wherein the at least one detector is configured to detect signal charged particles emitted from the sample and passing through the hole 340 (including passing outside the center circle of the hole 340).

[0107] In an example, backscattered charged particles (such as backscattered electrons) are typically fast and therefore less sensitive to acceleration fields (such as the acceleration field of the proximity electrode). Accordingly, the backscattered charged particles, including the backscattered electrons, are diffused or emitted over a wide angle away from the optical axis. Therefore, the proximity electrode with a larger opening is particularly beneficial for working with a backscattered charged particle detector (e.g., a backscattered electron detector) that is arranged to detect signal charged particles (e.g., backscattered charged particles / backscattered electrons).

[0108] According to an embodiment that can be combined with other embodiments, one or in particular both of the proximity electrode and the detector are arranged so that signal charged particles passing through the hole of the proximity electrode (including passing outside the central circle of the hole) are incident on the detector, in particular directly on the detector and / or on the detector without an electrode in between and / or on the detector without an electrode between the proximity electrode and the detector. In a specific example, the detector is a backscattered charged particle detector or a backscattered electron detector.

[0109] It is understood that the center circle is within the plane of the hole 340. It is understood that the center of the center circle is aligned with the center of the hole 340 or close to the center axis of the electrode 140. It is understood that the center circle avoids the protrusion 310 or there is no protrusion 310. It is understood that the center circle extends upward to the end or tip of one of the protrusions 310, preferably the end or tip of all of the protrusions 310.

[0110] Beneficially, more signal charged particles and signal charged particles at a wider angle can pass through the proximity electrode and be collected / detected without undesirably increasing field penetration from the above column.

[0111] According to embodiments that can be combined with other aspects and embodiments (e.g., protrusion 310 extends radially into hole 340), all areas of hole 340 are connected to each other in the plane of hole 340. Beneficially, shadowing is minimized for large hole areas, allowing improved signal charged particle detection and / or imaging.

[0112] According to embodiments that may be combined with other embodiments, the unsupported tip or end 330 of each protrusion 310 has a bulbous shape (which may be understood as an end having a radius that is increased relative to the radius at the middle or rod-shaped portion 320 of the corresponding protrusion) and / or is adapted to reduce the surface electric field at the unsupported tip or end 330.

[0113] According to an embodiment that can be combined with other embodiments described herein, the radius or width of the tip or end 330 of (each of) the protrusions is at least as large as the radius or width of the middle or rod-shaped portion 320 of the corresponding protrusion 310, and preferably larger than the radius or width of the middle or rod-shaped portion of the corresponding protrusion.

[0114] According to embodiments, which can be combined with other embodiments described herein, the radius or width of the tip or end 330 of (each of) the protrusions is at most twice the radius or width of the middle or shaft portion 320 of the respective protrusion 310 .

[0115] According to some embodiments that may be combined with other embodiments described herein, the (unsupported and / or free) tip or end 330 of one or more of the protrusions 310 (preferably all of the protrusions 310), respectively, has a bulbous shape or a radius that is larger than the radius at the middle or shaft-shaped portion 320 of the corresponding protrusion 310.

[0116] According to some embodiments that may be combined with other embodiments described herein, the (unsupported and / or free) tip or end 330 of one or more of the protrusions 310 (preferably all of the protrusions 310) are respectively adapted to have a reduced / low surface electric field, in particular at the (free and / or unsupported) tip or end 330.

[0117] Beneficially, the protrusion ends are rounded and a proximity electrode is obtained with a reduced peak surface electric field and low field penetration through the proximity electrode, thereby obtaining a low proximity electrode voltage.

[0118] It is understood that the protrusion 310 has (only) one (unsupported and / or free) tip or end 330. It is understood that the unsupported and / or free tip or end 330 of the protrusion 310 is disposed at an end opposite to the base or supported end of the protrusion 310. It is understood that the protrusion 310 is supported or cantilevered at the base of the protrusion 310. It is understood that each of the one or more protrusions is supported by or cantilevered from the body 300 proximate to the electrode 140.

[0119] Various aspects, embodiments and examples of retarding field apparatus are described below.

[0120] Figure 8 A retarding field device including a proximity electrode is shown according to various aspects and embodiments described herein.

[0121] According to one aspect, a deceleration field device for decelerating a primary charged particle beam before it is incident on a sample 150 comprises an objective lens 120 and a proximity electrode 140 arranged downstream of (a principal plane of) the objective lens 120 .

[0122] It is understood that the retarding field device is configured to reduce the energy of the primary charged particle beam in the column to a landing energy for landing on the sample 150. The retarding field device can be configured to decelerate the primary charged particle beam and accelerate the signal charged particles. In an example, the objective lens 120 and the proximity electrode 140 can be configured in combination to focus the primary charged particle beam.

[0123] According to embodiments, which can be combined with other aspects and embodiments, the proximity electrode 140 is arranged close to the objective lens 120 or within the effective field of the objective lens 120 .

[0124] According to embodiments, which can be combined with other aspects and embodiments, the proximity electrode 140 is adjacent to or close to the sample 150 and / or the sample stage. According to embodiments, the proximity electrode 140 is configured to control or provide control of the extraction field, in particular in the space between the proximity electrode 140 and the sample 150 or the sample stage.

[0125] The extraction field may be understood as a field used to extract and / or accelerate signal charged particles from the sample 150. The extraction field may be controlled or provided by the proximity electrode 140. It may be understood that the collection of signal charged particles may be controlled by controlling the extraction field.

[0126] The proximity electrode 140 may be configured to control the extraction field strength for extracting signal charged particles. It is understood that the predetermined potential U may be applied to the proximity electrode 140. 接近 230 to control the extraction field in the extraction region between the sample and the proximity electrode.

[0127] According to embodiments, which may be combined with other aspects and embodiments, the proximity electrode 140 is arranged or configured as the last element of a decelerating field device or a charged particle beam device in the direction of the primary charged particle beam before it impinges on the sample 150 .

[0128] The proximity electrode 140 may be arranged adjacent to the sample 150 and / or without electrodes and / or elements between the proximity electrode 140 and the sample 150. It is understood that the distance between the proximity electrode 140 and the sample 150 or the sample stage is smaller than the distance between the objective lens 120 and the sample 150 or the sample stage.

[0129] In an example, the distance between the proximity electrode 140 and the sample 150 or sample stage, in particular the operating distance or working distance or the distance during operation, is 10 mm or less, preferably 6 mm or less, more preferably 4 mm or less, and most preferably 2 mm or less.

[0130] Beneficially, the small distance between the proximity electrode 140 and the sample 150 allows for the collection of large angle signal charged particles through the aperture of the proximity electrode 140 .

[0131] According to embodiments, which can be combined with other aspects and embodiments, the proximity electrode 140 may be configured to decelerate the primary charged particle beam, in particular as a (most downstream) component or electrode of a decelerating field device.

[0132] According to an embodiment that can be combined with other aspects and embodiments, the proximity electrode 140 is adapted to be at a relative potential U 柱 210 at a more negative potential.

[0133] In the example, the proximity electrode 140 is at a potential U 接近 230, so that the potential U close to the electrode 接近 230 and the potential U of the column of the charged particle beam device 柱 210. Potential U of the first detector 检测 and / or the potential U of the objective lens 物镜 The potential difference between is adapted to decelerate the primary charged particle beam before incident on the sample.

[0134] Advantageously, a retarding field apparatus is provided.

[0135] In the example, the proximity electrode 140 is at a potential U 接近 230, so that the proximity electrode is at a potential U lower than the column potential U of the charged particle beam device. 柱 210 (eg, the potential U of the first detector 检测 Or the potential U of the objective lens 物镜 ) at a more negative potential.

[0136] In the example, the retarding field device provides the sample 150 (sample potential, U 样品 240) and the column of the charged particle beam device (column potential, U 柱 210), for example, a potential difference of 5 keV or greater, 15 keV or greater, or 30 keV or greater and / or 100 keV or less, 80 keV or less, or 60 keV or less.

[0137] It is understood that (the aperture of) the proximity electrode is adapted for passage of both the primary charged particle beam and the signal charged particles.It is understood that the primary charged particle beam and the signal particles propagate through the proximity electrode, in particular through the aperture, in different, eg (substantially) opposite directions.

[0138] It will be appreciated that the proximity electrode 140 is configured to allow the primary charged particle beam to pass through the proximity electrode through an aperture of the proximity electrode 140 to be incident on the sample 150 .

[0139] It is understood that the proximity electrode 140 is adapted to allow signal particles emitted from the sample to pass through the proximity electrode 140 (through the aperture of the proximity electrode 140 ).

[0140] According to an embodiment, the size of the hole close to the electrode 140 (light-passing hole size) is 5 mm. 2 or larger, preferably 10 mm 2 or larger, more preferably 15 mm 2 or larger, and most preferably 20 mm 2 or larger.

[0141] According to an embodiment, the diameter or (in-plane) width of the hole of the proximity electrode 140 is at least 5 times the distance between the proximity electrode 140 and the sample 150 or sample stage or at least 5 times the height of the space between the proximity electrode 140 and the sample 150 or sample stage.

[0142] Beneficially, a proximity electrode is provided having large pores which allow more signal charged particles to pass through to be collected.

[0143] The proximity electrode 140 can be configured to allow signal charged particles emitted at an angle of 5 degrees or greater, preferably 10 degrees or greater, or most preferably 15 degrees or greater to pass through. The angle of the emitted signal charged particles can be understood as relative to the optical axis of the charged particle beam device and / or the axis of the proximity electrode 140.

[0144] According to an embodiment, the size of the hole of the proximity electrode 140 and the distance therefrom allow signal charged particles from the sample 150 emitted at an angle of 5 degrees or greater, preferably 10 degrees or greater, or more preferably 15 degrees or greater to pass through the hole of the proximity electrode 140.

[0145] Aspects, embodiments and examples of charged particle beam apparatus are described below.

[0146] Fig. 9 A charged particle beam apparatus according to various aspects and embodiments described herein is shown.

[0147] According to one aspect, a charged particle beam device 100 for at least one of imaging and inspecting a sample includes: a beam emitter 110, the beam emitter 100 being used to emit a primary charged particle beam; and a deceleration field device, the deceleration field device being used to decelerate the primary charged particle beam before the primary charged particle beam is incident on a sample 150, the deceleration field device comprising an objective lens 120 and a proximity electrode 140 arranged downstream of (the main plane of) the objective lens 120; wherein the charged particle beam device 100 is adapted to guide the primary charged particle beam to the sample 150 along an optical axis 160 for generating signal charged particles from the sample 150.

[0148] The beam emitter 110 for emitting the primary charged particle beam may be a charged particle source, such as a cold field emitter (CFE) or a thermal field emitter (TFE) (e.g., a Schottky emitter). The beam emitter 110 may be a high current source and / or a high brightness source. A high current source may be understood as a source configured to generate at least 5 μA at 100 mrad.

[0149] The charged particle beam device may include a charged particle suppressor (not shown), a focusing lens 112 and / or a deflector 114 (the deflector 114 may be a beam alignment deflector and / or configured to align the primary charged particle beam to a beam limiting aperture 116). The beam limiting aperture 116 may be arranged between the beam emitter 110 and the objective lens 120. The beam limiting aperture 116 may be arranged to separate a first chamber including the beam emitter 110 from another chamber or chambers (e.g., a second chamber or a second chamber including the objective lens 120).

[0150] It is understood that the objective lens 120 is configured to focus the primary charged particle beam onto the sample 150. In the example, the objective lens 120 includes an upper pole piece and a lower pole piece and a coil ( Figure 8 1 . The objective lens 120 may include one or more electrodes that form an electrostatic lens component of the objective lens. The magnetic lens component and the electrostatic lens component may overlap to form a composite objective lens.

[0151] In an example, the charged particle beam device comprises a column. The column may be at ground potential. In an example, when the column is at ground potential, detection with the first detector and / or the second detector, in particular with one or more semiconductor detectors (such as PIN diodes) may be feasible, because the detector and the detector electronics may be arranged at ground potential.

[0152] It is understood that the charged particle beam device 100 is configured to guide the primary charged particle beam through a column of the charged particle beam device 100. The interior of the column is understood to be evacuated and / or at sub-atmospheric pressure, for example at 1 mbar or lower, 10 -5 mbar or lower, or even 10 -8 The charged particle beam device may be arranged at a pressure of 100 mbar or less (ultra-high vacuum). In an embodiment, the charged particle beam device comprises a vacuum housing. The beam emitter and the objective lens may be arranged within the vacuum housing of the charged particle beam device.

[0153] In an example, the charged particle beam device 100 may include a scanning deflector 122 ( Figure 8 The scanning deflector 122 may be configured to scan the primary charged particle beam over (the surface of) the sample 150.

[0154] It is understood that the axis close to the electrode 140, in particular the axis of the hole close to the electrode 140, is aligned with the optical axis 160 of the charged particle beam device 100, with the primary charged particle beam and / or with the axis of the objective lens 120. In an example, the optical axis 160 of the charged particle beam device 100 and the axis close to the electrode 140, in particular the axis of the hole close to the electrode 140, are collinear and / or coincident.

[0155] In an example, the charged particle beam device 100 includes one or more detectors configured to detect signal charged particles emitted from the sample 150 and passing through (the hole of) the proximity electrode 140, preferably including the outside of a central circle passing through the hole of the proximity electrode 140, the central circle avoiding the protrusion and extending upward to the end of the protrusion of the proximity electrode 140.

[0156] In an example, the proximity electrode 140 is aligned with at least one of the one or more detectors, such as the BSE detector 134 ( Figure 8 as shown).

[0157] According to an embodiment, which can be combined with other aspects and embodiments, the proximity electrode 140 is arranged as the last element of the charged particle beam device 100 in the direction of the primary charged particle beam before the primary charged particle beam is incident on the sample 150. Beneficially, the proximity electrode is adjacent to or close to the sample and facilitates a suitable incident energy of the primary charged particle beam and extraction of signal charged particles.

[0158] In an example, the proximity electrode 140 is arranged near or at the front end of the vacuum housing of the charged particle beam device 100 and / or protrudes into a sample chamber in which the sample 150 and / or the sample stage 152 are arranged. In an example, the sample chamber may be configured for sub-atmospheric pressure, such as high vacuum. In an example, the vacuum housing of the charged particle beam device 100 may be configured for ultra-high vacuum and / or for a higher vacuum or lower pressure than the sample chamber.

[0159] The charged particle beam device 100 may include a sample stage 152 configured to support a sample 150. The sample stage 152 may have a support surface extending in particular in an xy plane. The sample 150 may be placed on the sample stage 152 of the charged particle beam device 100.

[0160] It can be understood that when the primary charged particle beam is incident on the sample 150, signal charged particles, such as secondary charged particles (SE) and / or backscattered charged particles (BSE), are emitted or sent from the sample 150, and the signal charged particles can be understood as being detectable by at least one of one or more detectors (e.g., BSE detector 134, SE detector 132).

[0161] According to an embodiment, which can be combined with other aspects and embodiments, the charged particle beam device 100 comprises a first detector, which is preferably configured to detect backscattered signal charged particles, i.e., a BSE detector 134. The first detector may be arranged between the objective lens 120 and the sample 150 or the sample stage 152. The first detector may preferably be arranged between the proximity electrode 140 and the objective lens 120. In an example, the first detector is a semiconductor detector, such as a PIN diode.

[0162] It is understood that signal charged particles (e.g., backscattered electrons) passing through the proximity electrode 140 can be accelerated toward the first detector (e.g., BSE detector 134) so ​​that detection is efficient. In an example, by setting the first detector at a corresponding potential, the first detector can be used as an accelerating electrode to accelerate the signal charged particles.

[0163] It will be appreciated that accelerating the signal charged particles, and in particular the backscattered charged particles, is particularly beneficial for detecting the signal charged particles at low landing energy settings. This is beneficial at landing energies below 10 keV, below 3 keV, or even below 1 keV, and for detecting backscattered electrons that lose energy traveling through the sample (e.g., when backscattered from greater depths within the sample or from deep trenches or features with high aspect ratios).

[0164] The first detector may be a multi-channel backscattered electron detector, preferably comprising a plurality of detection segments, the signals in the plurality of detection segments being separately processed, for example separately mixed and / or combined. One or more signals from the first detector, in particular one or more signals from a plurality of detection segments, may be combined for forming an image and / or processed separately for improving the topographic contrast.

[0165] The first detector may be an in-lens detector. The first detector may have an annular detection surface. The axis of the first detector may be colinear or coincident with the optical axis of the charged particle beam device and / or with the axis of the proximity electrode 140. In some embodiments, the first detector is an in-lens detector having an aperture that allows the primary charged particle beam to pass through and having an annular detection surface surrounding the aperture.

[0166] According to an embodiment that can be combined with other aspects and embodiments, the charged particle beam device 100 includes one or more of at least one of an electrode, a deflector 114 and / or a lens (e.g., a condenser lens 112 and / or an objective lens 120) for guiding the primary charged particle beam to the sample along an optical axis for generating signal charged particles from the sample 150. The charged particle beam device 100 can be configured to image and / or inspect the sample 150 based on the signal charged particles emitted from the sample 150.

[0167] The charged particle beam device 100 may include a beam splitter 130 configured to separate the primary charged particle beam from the signal charged particles, the beam splitter 130 preferably being arranged between the beam emitter 110 and the objective lens 120. The beam splitter 130 may include at least one magnetic deflector so that the signal charged particles deviate from the optical axis 160 of the charged particle beam device 100. In an example, the beam splitter is a Wien filter.

[0168] The charged particle beam device 100 may include a second detector (e.g., SE detector 132) configured to detect signal charged particles, preferably second signal charged particles (e.g., secondary electrons). The second detector may be configured to detect signal charged particles separated from the primary charged particle beam by the beam splitter 130. The second detector may be arranged between the objective lens 120 and the beam emitter 110. In an example, the second detector is a secondary electron detector.

[0169] Fig.10The relative primary beam spot sizes of various beam currents of a charged particle beam device having a proximity electrode according to a first design 1010 and having a proximity electrode according to a baseline design 1020 are shown. As shown, the charged particle beam device having a proximity electrode with a protrusion has a primary charged particle beam spot size substantially similar to that of a primary charged particle beam device having a proximity electrode without a protrusion. Therefore, the proximity electrode according to the embodiments and examples as described herein can provide corresponding benefits without distorting the primary charged particle beam.

[0170]

[0013] Various aspects, embodiments and examples of methods for imaging and / or inspecting a sample are described below.

[0171] Fig.11 Depicted are methods of imaging and / or inspecting a sample using a charged particle beam device having proximity electrodes according to various aspects and embodiments described herein.

[0172] According to one aspect, a method for imaging and / or inspecting a sample 150 using a charged particle beam device 100 having a proximity electrode 140 may include: emitting a primary charged particle beam 1110; guiding the primary charged particle beam through a column of the charged particle beam device 1120; and focusing 1130 the primary charged particle beam and decelerating the primary charged particle beam using a deceleration field device 1140.

[0173] According to an embodiment that can be combined with other embodiments described herein, the proximity electrode 140 includes a central circle within the plane of the hole of the proximity electrode 140, wherein the central circle avoids the protrusion, and the method includes guiding the primary charged particle beam through the hole, in particular (substantially or completely) through the central circle.

[0174] According to some embodiments, the proximity electrode 140 includes a central circle within the plane of the hole of the proximity electrode 140, wherein the central circle avoids the protrusion, and the method includes detecting signal charged particles passing through the proximity electrode 140 (the hole), preferably including outside the central circle passing through the hole of the proximity electrode 140.

[0175] According to some embodiments, the proximity electrode 140 is arranged as the last element of the charged particle beam device in the direction of the primary charged particle beam before the primary charged particle beam is incident on the sample, and the method includes setting the proximity electrode comprising / having a protrusion at a potential adapted to reduce penetration of the column field through the proximity electrode and reaching the sample.

[0176] In an example, the phrase "at a potential adapted to reduce penetration of the pillar field" may be understood to mean: wherein penetration of the pillar field through the proximity electrode is smaller when the proximity electrode is set at said potential than when the proximity electrode is set at a potential equal to the potential of the pillar.

[0177] Charged particle beam equipment can be used to image and / or inspect samples, such as for at least one of critical dimension measurement, defect review, charged particle beam mask inspection, and metrology and inspection processes such as charged particle beam metrology and hot spot inspection, and charged particle beam wafer inspection.

[0178] Furthermore, imaging and / or inspection of a sample may be understood as imaging and / or inspection of 3D structures, for example semiconductor samples (such as wafers) and / or features (such as FinFETs and NANDs).

[0179] In the present disclosure, approaching electrodes, charged particle beam equipment, parts of charged particle beam equipment and methods related to charged particle beam equipment illustratively and non-restrictively relate to electrons. The term electrons particularly includes secondary electrons and / or backscattered electrons, particularly both secondary electrons and backscattered electrons (SE and BSE). However, it should be understood that the various aspects, embodiments and examples described herein can be applied to other microparticles, such as secondary charged particles and / or backscattered charged particles in the form of positive ions or negative ions, so as to obtain sample images or inspection results. Therefore, in various aspects, embodiments and examples described herein, approaching electrodes, charged particle beam equipment, parts of charged particle beam equipment and methods related to charged particle beam equipment are not limited to electrons and can refer to charged particles.

[0180] As referred to herein, "sample", "sample" or "wafer" includes but is not limited to semiconductor wafers, semiconductor workpieces and other workpieces, such as storage disks, etc. "Sample" can specifically be any workpiece that is structured or any workpiece on which a material is deposited. The sample, sample or wafer may include a surface to be inspected and / or imaged, such as a structured surface or a surface on which a layer or material pattern has been deposited. For example, the sample can be a substrate or a wafer on which a plurality of electronic devices to be inspected are provided. According to various aspects, embodiments and examples, the apparatus and methods described herein relate to charged particle or electron beam inspection (EBI), critical dimension measurement and defect review applications, wherein the apparatus and methods described herein can be beneficially used to obtain increased throughput and improved detection accuracy. According to various aspects, embodiments and examples, a charged particle device or electron beam inspection (EBI) device, a critical dimension measurement (CD) tool and / or a defect review (DR) tool can be provided, wherein high resolution, a large field of view and a high scanning speed can be achieved.

[0181] The numbered examples are described below:

[0182] According to Example 1, a proximity electrode for a charged particle beam device is provided, the proximity electrode comprising a body having a hole therein; and the body having a plurality of protrusions radially cantilevered into the hole, the hole and the protrusions having n-fold rotational symmetry, where n is an integer.

[0183] According to Example 2, a proximity electrode according to Example 1 is provided, wherein the minimum radius of curvature of each of the plurality of protrusions is greater than 5% of the width and / or diameter of the corresponding protrusion, and / or wherein the protrusion has a minimum radius of curvature such that the maximum magnitude of the surface electric field on the protrusion is less than 3 times the maximum magnitude of the surface electric field on the body of the proximity electrode.

[0184] According to Example 3, a proximity electrode according to Example 1 or 2 is provided, wherein the minimum radius of curvature of each of the protrusions in a plane perpendicular to the plane of the proximity electrode and / or in a plane perpendicular to the plane of the hole of the proximity electrode is larger than the minimum radius of curvature of the corresponding protrusion in the plane of the proximity electrode and / or in the plane of the hole of the proximity electrode.

[0185] According to Example 4, a proximity electrode according to any one of Examples 1 to 3 is provided, wherein the minimum radius of curvature at the free end and / or tip of each protrusion is equal to or greater than half the width at the middle and / or rod-shaped portion of the corresponding protrusion.

[0186] According to example 5, there is provided a proximity electrode according to any one of examples 1 to 4, wherein the unsupported end of each protrusion has a bulbous shape adapted to reduce a surface electric field at the unsupported end.

[0187] According to Example 6, there is provided a proximity electrode according to any one of Examples 1 to 5, wherein a length of each protrusion is at least 5% of a radius of the hole and at most 80% of a radius of the hole.

[0188] According to Example 7, there is provided a proximity electrode according to any one of Examples 1 to 6, wherein the clearing area of ​​the hole in the plane of the hole is at least 10 mm 2 .

[0189] According to Example 8, there is provided a proximity electrode according to any one of Examples 1 to 7, the proximity electrode further comprising a center circle in the plane of the hole, the center circle avoiding the protrusions and extending upward to the ends and / or tips of one or all of the protrusions.

[0190] According to Example 9, a proximity electrode according to any one of Examples 1 to 8 is provided, wherein the proximity electrode is aligned with at least one detector, the at least one detector being configured to detect signal charged particles emitted from the sample and passing through holes including the outside of the circle, and / or wherein the proximity electrode is arranged so that signal charged particles emitted from the sample and passing through holes including the outside of the circle are incident on a backscattered charged particle detector.

[0191] According to Example 10, there is provided a proximity electrode according to any one of Examples 1 to 9, wherein all areas of the apertures are connected to each other in the plane of the apertures.

[0192] According to Example 11, a charged particle beam device for at least one of imaging and inspecting a sample is provided, the charged particle beam device comprising: a beam emitter for emitting a primary charged particle beam; and a deceleration field device for decelerating the primary charged particle beam before the primary charged particle beam is incident on the sample, the deceleration field device comprising an objective lens and a proximity electrode according to any one of Examples 1 to 10, the proximity electrode being arranged downstream of a principal plane of the objective lens; wherein the charged particle beam device is adapted to guide the primary charged particle beam to the sample along an optical axis to generate signal charged particles from the sample.

[0193] According to example 12, the charged particle beam device according to example 11 is provided, wherein the proximity electrode is arranged as the last element of the charged particle beam device in the direction of the primary charged particle beam before the primary charged particle beam is incident on the sample.

[0194] According to example 13, there is provided a charged particle beam apparatus according to example 11 or 12, wherein a diameter of the hole close to the electrode is at least 3 times the height of a space between the close electrode and the sample.

[0195] According to example 14, there is provided a charged particle beam apparatus according to any one of examples 11 to 13, wherein the proximity electrode is adapted to be at a potential more negative than the column potential.

[0196] According to example 15, a charged particle beam device according to any one of examples 11 to 14 is provided, wherein the proximity electrode is arranged near the objective lens and / or within the effective field of the objective lens.

[0197] According to Example 16, there is provided a charged particle beam device according to any one of Examples 11 to 15, wherein a diameter of the circle is at least twice the height of a space separating the proximity electrode from the sample.

[0198] According to Example 17, there is provided a method of at least one of imaging and inspecting a sample using a charged particle beam device having a proximity electrode according to any one of Examples 1 to 10.

[0199] According to Example 18, there is provided a method according to Example 17, wherein the proximity electrode is a proximity electrode according to any one of Examples 8 to 10, and the method further comprises directing the primary charged particle beam through the hole, through the center circle.

[0200] According to Example 19, there is provided a method according to Example 17 or 18, wherein the proximity electrode is a proximity electrode according to any one of Examples 8 to 10, and the method further comprises detecting signal charged particles passing through a hole including the outside of the circle.

[0201] According to Example 20, a method according to any one of Examples 17 to 19 is provided, wherein the proximity electrode is preferably a proximity electrode according to Example 7 or according to any one of Examples 1 to 10, and the method further includes setting the proximity electrode including a protrusion at an electric potential adapted to reduce penetration of the column field through the proximity electrode and reaching the sample.

[0202] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope of the embodiments is determined by the claims that follow.

Claims

1. A proximity electrode for a charged particle beam device, the proximity electrode comprising: a body having a hole therein; and The body has a plurality of protrusions radially overhanging into the hole, the hole and the protrusions having n-fold rotational symmetry, n being an integer.

2. A proximity electrode as described in claim 1, wherein the minimum radius of curvature of each of the plurality of protrusions is greater than 5% of the width or diameter of the corresponding protrusion, or wherein the protrusion has a minimum radius of curvature so that the maximum magnitude of the surface electric field on the protrusion is less than 3 times the maximum magnitude of the surface electric field on the body of the proximity electrode.

3. A proximity electrode as described in claim 1, wherein the minimum radius of curvature of each of the protrusions in a plane perpendicular to the plane of the proximity electrode or in a plane perpendicular to the plane of the hole of the proximity electrode is larger than the minimum radius of curvature of the corresponding protrusion in the plane of the proximity electrode or in the plane of the hole of the proximity electrode. 4 . The proximity electrode of claim 1 , wherein a minimum radius of curvature at a free end or a tip of each protrusion is equal to or greater than half of a width at a middle or a rod-shaped portion of the corresponding protrusion.

5. The proximity electrode of any one of claims 1 to 4, wherein the unsupported end of each protrusion has a bulbous shape adapted to reduce the surface electric field at the unsupported end.

6. A proximity electrode as claimed in any one of claims 1 to 4, wherein the length of each protrusion is at least 5% and at most 80% of the radius of the hole.

7. A proximity electrode as claimed in any one of claims 1 to 4, wherein the clearing area of ​​the aperture in the plane of the aperture is at least 10 mm 2 .

8. The proximity electrode of any one of claims 1 to 4, further comprising a central circle in the plane of the aperture, the central circle avoiding the protrusions and extending upwardly to the ends or tips of one or all of the protrusions.

9. A proximity electrode as described in claim 8, wherein the proximity electrode is aligned with at least one detector, and the at least one detector is configured to detect signal charged particles emitted from the sample and passing through the hole including the outside of the circle, or wherein the proximity electrode is arranged so that the signal charged particles emitted from the sample and passing through the hole including the outside of the circle are incident on the backscattered charged particle detector.

10. The proximity electrode of any one of claims 1 to 4, wherein all areas of the holes are connected to each other in the plane of the holes.

11. A charged particle beam device for at least one of imaging and inspecting a sample, the charged particle beam device comprising: a beam emitter for emitting a primary charged particle beam; as well as a retarding field device for retarding the primary charged particle beam before the primary charged particle beam is incident on the sample, the retarding field device comprising an objective lens and a proximity electrode arranged downstream of a principal plane of the objective lens; wherein the charged particle beam device is adapted to direct the primary charged particle beam along an optical axis to the sample to generate signal charged particles from the sample; The proximity electrode comprises a body having a hole therein; and the body has a plurality of protrusions radially overhanging into the hole, the hole and the protrusions having n-fold rotational symmetry, n being an integer.

12. The charged particle beam device of claim 11, wherein the proximity electrode is arranged as the last element of the charged particle beam device in the direction of the primary charged particle beam before the primary charged particle beam is incident on the sample. 13 . The charged particle beam apparatus of claim 11 , wherein a diameter of the hole of the proximity electrode is at least 3 times the height of a space between the proximity electrode and the sample.

14. A charged particle beam apparatus as claimed in claim 11, wherein the proximity electrode is adapted to be at a potential more negative than a column potential.

15. The charged particle beam apparatus according to any one of claims 11 to 14, wherein the proximity electrode is arranged near the objective lens or within an effective field of the objective lens.

16. A charged particle beam apparatus as claimed in any one of claims 11 to 14, wherein the diameter of the circle is at least twice the height of the space separating the proximity electrode from the sample.

17. A method for at least one of imaging and inspecting a sample using a charged particle beam apparatus having a proximity electrode according to claim 1.

18. The method of claim 17, wherein the proximity electrode is a proximity electrode according to claim 8, the method further comprising directing the primary charged particle beam through the aperture, through the central circle.

19. The method of claim 17, wherein the proximity electrode is a proximity electrode according to claim 8, the method further comprising detecting signal charged particles passing through the hole comprising an outer portion of the circle.

20. The method of claim 17, wherein the proximity electrode is the proximity electrode of claim 7, the method further comprising placing the proximity electrode including the protrusion at a potential adapted to reduce penetration of a column field through the proximity electrode and to the sample.

Images