Scanning Electron Microscopy System

Abstract

To prevent occurrence of deflection aberration in an electron beam to be collected and analyzed with a deflector group.SOLUTION: A scanning type electron microscopy (SEM) system includes a plurality of electron beam sources configured to generate primary electron beams, and an electron optical column array with a plurality of electro-optical columns. The electro-optical column has an electro-optical element. The electro-optical element includes a deflector layer configured to be driven by a common controller shared by at least some of the electro-optical columns, and includes a trim deflector layer configured to be driven by an individual controller. The electro-optical elements are arranged to form an electron beam channel, and the electron beam channel is configured to direct a primary electron beam onto a specimen fixed on a stage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates generally to wafer and photomask / reticle characterization and preparation, and more particularly to array-based characterization tools. [Background technology]

[0002] In the manufacture of semiconductor devices, such as logic and memory devices, the various features and multiple layers present in the semiconductor devices are typically formed by processing the semiconductor devices using multiple semiconductor fabrication and metrology processes. In the leading manufacturing processes, features are printed onto the semiconductor device, such as a wafer, using a photomask / reticle. As semiconductor devices become smaller laterally and larger vertically, it is imperative to develop enhanced inspection and review equipment and procedures to increase the sensitivity and throughput of the photomask / reticle and wafer inspection processes.

[0003] One characterization technology is electron beam characterization, e.g., scanning electron microscopy (SEM). In some SEMs, scanning electron microscopy is performed through secondary electron beam collection (e.g., secondary electron (SE) imaging systems). In some SEMs, scanning electron microscopy is performed by splitting a single electron beam into multiple beams and using a single electron optical column to individually tune and scan the multiple beams (e.g., multi-beam SEM systems). In some SEMs, scanning electron microscopy is performed with an SEM system that has multiple electron optical columns (e.g., multi-column SEM systems).

[0004] In an SEM system, a specimen can be imaged by collecting and analyzing the electron beam, including electrons emitted and / or backscattered from the specimen, while a primary electron beam is scanned across the specimen. A set of deflectors intervene as the electron beam is directed (e.g., focused or steered) toward the specimen and then returned to a detector within the SEM system's electron optical column. The use of these deflectors can introduce deflection aberrations into the collected and analyzed electron beam. Nonuniformities in the deflection field can cause such deflection aberrations. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2002 / 0117967 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, it would be advantageous to provide a system and method that obviates the above-mentioned shortcomings. [Means for solving the problem]

[0007] In accordance with one or more embodiments of the present disclosure, a scanning electron microscope (SEM) system is disclosed. In some embodiments, the SEM system includes a plurality of electron beam sources. In some embodiments, at least some of the electron beam sources are configured to generate a primary electron beam. In some embodiments, the SEM system includes an electron optical column array with a plurality of electron optical columns. In some embodiments, an electron optical column of the plurality of electron optical columns includes a plurality of electron optical elements. In some embodiments, the plurality of electron optical elements includes a deflector layer. In some embodiments, the deflector layer includes an upper deflector configured to receive a first voltage and a lower deflector configured to receive an additional voltage. In some embodiments, the deflector layer is configured to be driven by a common controller shared by at least some of the plurality of electron optical columns. In some embodiments, the plurality of electron optical elements includes a trim deflector layer. In one embodiment, the trim deflector layer includes an upper trim deflector configured to receive a first trim voltage and a lower trim deflector configured to receive an additional trim voltage. In another embodiment, the trim deflector layer is configured to be driven by individual controllers. In another embodiment, the plurality of electron optical elements are arranged to form an electron beam channel. In another embodiment, the electron beam channel is configured to direct a primary electron beam to a specimen held on a stage. In another embodiment, the specimen emits an electron beam in response to the primary electron beam. In another embodiment, the electron optical column includes at least one electron detector. In another embodiment, the electron beam channel is configured to direct the electron beam to the at least one electron detector.

[0008] In accordance with one or more embodiments of the present disclosure, an electron-optical system is disclosed. In some embodiments, the electron-optical system includes an electron-optical column array. In some embodiments, the electron-optical column array includes a plurality of electron-optical columns. In some embodiments, an electron-optical column of the plurality of electron-optical columns includes a plurality of electron-optical elements. In some embodiments, the plurality of electron-optical elements includes a deflector layer. In some embodiments, the deflector layer includes an upper deflector configured to receive a first voltage and a lower deflector configured to receive an additional voltage. In some embodiments, the deflector layer is configured to be driven by a common controller shared by at least some of the plurality of electron-optical columns. In some embodiments, the plurality of electron-optical elements includes a trim deflector layer. In some embodiments, the trim deflector layer includes an upper trim deflector configured to receive a first trim voltage and a lower trim deflector configured to receive an additional trim voltage. In one embodiment, the trim deflector layer is configured to be driven by an individual controller. In another embodiment, the plurality of electron optical elements are arranged to form an electron beam channel. In another embodiment, the electron beam channel is configured to direct a primary electron beam to a specimen held on a stage. In another embodiment, the specimen emits an electron beam in response to the primary electron beam. In another embodiment, the electron optical column includes at least one electron detector. In another embodiment, the electron beam channel is configured to direct the electron beam to the at least one electron detector.

[0009] In accordance with one or more embodiments of the present disclosure, a scanning electron microscope (SEM) system is disclosed. In some embodiments, the SEM system includes multiple electron beam sources. In some embodiments, at least some of the electron beam sources are configured to generate a primary electron beam. In some embodiments, the SEM system includes an electron optical column array with multiple electron optical columns. In some embodiments, at least some of the electron optical columns include multiple electron optical elements. In some embodiments, the multiple electron optical elements are arranged to form a conical electron beam channel. In some embodiments, the conical electron beam channel is configured to direct the primary electron beam toward a specimen held on a stage. In some embodiments, the specimen emits an electron beam in response to the primary electron beam. In some embodiments, at least some of the electron optical columns include at least one electron detector. In some embodiments, the conical electron beam channel is configured to direct the electron beam toward the at least one electron detector.

[0010] In accordance with one or more embodiments of the present disclosure, an electron optical system is disclosed. In some embodiments, the electron optical system includes an electron optical column array. In some embodiments, the electron optical column array includes a plurality of electron optical columns. In some embodiments, an electron optical column of the plurality of electron optical columns includes a plurality of electron optical elements. In some embodiments, the plurality of electron optical elements are arranged to form a conical electron beam channel. In some embodiments, the conical electron beam channel is configured to direct a primary electron beam toward a specimen held on a stage. In some embodiments, the specimen emits an electron beam in response to the primary electron beam. In some embodiments, the electron optical column includes at least one electron detector. In some embodiments, the conical electron beam channel is configured to direct the electron beam toward the at least one electron detector.

[0011] A characterization system is disclosed in accordance with one or more embodiments of the present disclosure. In some embodiments, the characterization system includes a plurality of radiation sources. In some embodiments, at least some of the radiation sources are configured to generate a primary radiation beam. In some embodiments, the characterization system includes a column array. In some embodiments, the column array includes a plurality of columns. In some embodiments, a column of the plurality of columns includes a plurality of elements. In some embodiments, the plurality of elements includes a deflector layer configured to receive a voltage. In some embodiments, the deflector layer is configured to be driven by a common controller shared by at least some of the plurality of columns. In some embodiments, the plurality of elements includes a trim deflector layer configured to receive a trim voltage. In some embodiments, the trim deflector layer is configured to be driven by an individual controller. In some embodiments, the plurality of elements are arranged to form a beam channel. In some embodiments, the beam channel is configured to direct the primary radiation beam toward a specimen held on a stage. In some embodiments, the sample generates a radiation beam in response to the primary radiation beam, and in some embodiments, the column includes at least one detector, and in some embodiments, the beam channel is configured to direct the radiation beam generated by the sample to the at least one detector.

[0012] Those skilled in the art will be able to better appreciate the many advantages of the present disclosure by reviewing the accompanying drawings, in which: [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic block diagram of a scanning electron microscope (SEM)-based characterization tool according to one or more embodiments of the present disclosure. [Figure 2]FIG. 1 is a simplified schematic diagram of an electron optical column included in an SEM-based characterization tool according to one or more embodiments of the present disclosure. [Figure 3] FIG. 1 is a schematic block diagram of an optical characterization tool according to one or more embodiments of the present disclosure. [Figure 4] FIG. 1 is a simplified schematic diagram of a characterization system having a characterization tool and a controller in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Reference will now be made in detail to the disclosed subject matter, which is illustrated in the accompanying drawings.

[0015] 1-4 collectively, an array-based characterization tool according to one or more embodiments of the present disclosure is disclosed.

[0016] Embodiments of the present disclosure are directed to providing an SEM-based characterization tool in which a common-mode voltage (e.g., common to the electron optical columns in the electron optical column array) is applied to a set of deflectors in the electron optical columns in the electron optical column array. It is noted that the characterization tool of the present disclosure may be configured as any imaging-based characterization tool known in the art, including, but not limited to, an inspection tool, a review tool, an imaging-based overlay metrology tool, etc.

[0017] Embodiments of the present disclosure are also directed to an SEM-based characterization tool that applies a voltage to an additional set of deflectors in each electron optical column in an electron optical column array substantially simultaneously with the application of a common-mode voltage to the set of deflectors, where the additional voltage is dynamic and unique to each electron optical column. It is noted that generating a voltage driver capable of providing a common-mode voltage that can simultaneously provide a unique, highly accurate, dynamic voltage to each electron optical column is not feasible with SEM-based characterization tools known in the art and is believed to be impractical and difficult.

[0018] Embodiments of the present disclosure are also directed to reducing the number, complexity, volume, and power consumption of electronic components in SEM-based characterization tools.Embodiments of the present disclosure are also directed to improving secondary electron capture rates in SEM-based characterization tools.Embodiments of the present disclosure are also directed to reducing deflection aberrations and increasing deflection field uniformity of deflectors in SEM-based characterization tools.

[0019] Embodiments of the present disclosure are directed to providing a characterization tool in which a common-mode static and / or dynamic voltage (e.g., common to the columns in the column array) is applied to a set of deflectors in columns in a column array. Embodiments of the present disclosure are also directed to a characterization tool that applies a voltage to an additional set of deflectors in each column in the column array substantially simultaneously with the application of the common-mode voltage to the set of deflectors, where the additional voltage is static and / or dynamic and unique to each column. Embodiments of the present disclosure are also directed to reducing the number, complexity, volume, and power consumption of components in the characterization tool. Embodiments of the present disclosure are also directed to improving capture efficiency in the characterization tool. Embodiments of the present disclosure are also directed to reducing deflection aberrations of deflectors in the characterization tool and increasing deflection field uniformity.

[0020] 1 and 2 generally depict a scanning electron microscope (SEM)-based characterization tool 100 according to one or more embodiments of the present disclosure.

[0021] 1 depicts a simplified schematic representation of an SEM-based characterization tool 100 according to one or more embodiments of the present disclosure. The SEM-based characterization tool 100 according to an embodiment includes an electron beam source array 102. In some embodiments, the electron beam source array 102 includes one or more electron beam sources. For example, the electron beam source array 102 may include, but is not limited to, a first electron beam source 104a, a second electron beam source 104b, a third electron beam source 104c, and / or at least a fourth electron beam source 104d. In some embodiments, the one or more electron beam sources include electron beam emitters or electron guns.

[0022] In addition, the SEM-based characterization tool 100 according to an embodiment includes an electron optical column array 108. Furthermore, in an embodiment, the electron optical column array 108 includes one or more electron optical columns. For example, the electron optical column array 108 can include, but is not limited to, a first electron optical column 110a, a second electron optical column 110b, a third electron optical column 110c, and / or at least a fourth electron optical column 110d.

[0023] Additionally, in embodiments, one or more primary electron beams are generated by one or more electron beam sources. For example, primary electron beams 106a, 106b, 106c, and 106d can be generated by electron beam sources 104a, 104b, 104c, and 104d. Furthermore, in embodiments, one or more primary electron beams are directed (e.g., focused or steered) to one or more electron optical columns in electron optical column array 108. For example, primary electron beams 106a, 106b, 106c, and 106d can be directed to electron optical columns 110a, 110b, 110c, and 110d in electron optical column array 108. In some embodiments, one or more source-side electron optical elements in electron beam source array 102 split the electron beams generated by one or more electron beam sources and direct them to two or more electron optical columns in electron optical column array 108.

[0024] In some embodiments, one or more of the electron optical columns may include one or more electron optical elements. For example, electron optical columns 110a, 110b, 110c, and 110d may include electron optical elements 112a, 112b, 112c, and 112d. In other examples, the one or more electron optical elements may include, but are not limited to, one or more electrostatic lenses, one or more electromagnetic lenses, etc.

[0025] In embodiments, one or more primary electron beams are directed by one or more electron optical columns to a specimen 114 held on a specimen stage 116. For example, primary electron beams 106a, 106b, 106c, and 106d may be directed by electron optical columns 110a, 110b, 110c, and 110d to a specimen 114 held on the specimen stage 116. In embodiments, one or more secondary electron beams may be emitted and / or backscattered by the specimen 114 in response to the one or more primary electron beams impinging on the specimen 114. For example, secondary electron beams 118a, 118b, 118c, and 118d may be emitted and / or backscattered by the specimen 114 in response to the primary electron beams 106a, 106b, 106c, and 106d impinging on the specimen 114. As an example, secondary electrons may be emitted from the specimen 114 in response to the primary electron beams 106a, 106b, 106c, and 106d. Additionally, electrons from the primary electron beams 106a, 106b, 106c, and 106d may be backscattered by the specimen 114.

[0026] It is noted that because secondary electron beams 118a, 118b, 118c, and 118d are wider than primary electron beams 106a, 106b, 106c, and 106d, the electrons in secondary electron beams 118a, 118b, 118c, and 118d will be slower than the electrons in primary electron beams 106a, 106b, 106c, and 106d. In addition, it is noted that because energy equivalent to the landing energy may be lost by the electrons in primary electron beams 106a, 106b, 106c, and 106d when forming secondary electron beams 118a, 118b, 118c, and 118d due to emission and / or backscattering, the electrons in secondary electron beams 118a, 118b, 118c, and 118d will be slower than the electrons in primary electron beams 106a, 106b, 106c, and 106d.

[0027] Specimen 114 may include any specimen suitable for inspection and / or review. For example, but not limited to, specimen 114 may include a photomask / reticle, a semiconductor wafer, etc. The term "wafer" in this disclosure refers to a substrate formed of a semiconductor and / or non-semiconductor material. For example, in the case of semiconductor materials, wafers may be formed of, but not limited to, monocrystalline silicon, gallium arsenide, and / or indium phosphide. Therefore, the terms "wafer" and "specimen" may be used interchangeably in this disclosure. Therefore, the above description should be construed as merely illustrative and not limiting on the scope of the present disclosure. It should be noted that a wide variety of devices may be formed on a wafer, and the term "wafer" in this application contemplates a wafer having any type of device formed thereon known in the art. Therefore, the above description should be construed as merely illustrative and not limiting on the scope of the present disclosure.

[0028] The specimen stage 116 can include any suitable mechanical and / or robotic assembly known in the art of electron beam microscopy. In some embodiments, the specimen stage 116 is a drivable stage. For example, the specimen stage 116 can include one or more translation stages suitable for selectively translating the specimen 114 along one or more linear directions (e.g., x-direction, y-direction, and / or z-direction). Alternatively, the specimen stage 116 can include one or more rotation stages suitable for selectively rotating the specimen 114 along a rotational direction. Alternatively, the specimen stage 116 can include rotation and translation stages suitable for selectively translating the specimen 114 along a linear direction and / or rotating the specimen 114 along a rotational direction. According to another example, the specimen stage 116 can be configured to translate or rotate the specimen 114 for positioning, focusing, and / or scanning according to a selected inspection or metrology algorithm, including several known in the art.

[0029] FIG. 2 depicts a simplified schematic representation of an electron optical column 110a included in an SEM-based characterization tool 100 according to one or more embodiments of the present disclosure.

[0030] Although embodiments of the present disclosure are directed to generating one or more secondary electron beams 118a by impinging one or more primary electron beams 106a on the surface of the specimen 114, it is noted that one or more primary electron beams 106a have been omitted from FIG. 2 for clarity. It is noted, however, that one or more primary electron beams 106a can be directed at the specimen 114 and can be done in a manner that does not affect the collection of one or more secondary electron beams 118a traveling in the opposite direction within the electron optical column 110a. Therefore, the above description should be taken as merely illustrative and not as a limitation on the scope of the present disclosure.

[0031] It is noted that all descriptions of primary electron beam 106a may, for purposes of this disclosure, be extended to primary electron beams 106b, 106c, and 106d. Additionally, it is noted that all descriptions of electron optical column 110a may, for purposes of this disclosure, be extended to electron optical columns 110b, 110c, and 110d. It is further noted that all descriptions of electron optical element 112a may, for purposes of this disclosure, be extended to electron optical elements 112b, 112c, and 112d. It is further noted that all descriptions of secondary electron beam 118a may, for purposes of this disclosure, be extended to secondary electron beams 118b, 118c, and 118d. Accordingly, the foregoing descriptions should be construed as merely illustrative and not as limitations on the scope of the present disclosure.

[0032] In some embodiments, the electron optical column 110a includes one or more detectors 200 configured to detect one or more secondary electron beams 118a from the specimen 114. For example, the one or more detectors 200 can include, but are not limited to, one or more secondary electron detectors. Alternatively, the one or more detectors 200 can include, but are not limited to, one or more backscattered electron detectors. For simplicity, the remainder of this disclosure will discuss various embodiments of the present disclosure in the context of secondary electron detection. However, it is recognized herein that the electron optical column 110a can be configured for secondary electron detection from the specimen 114 and / or for backscattered electron detection. Therefore, the scope of the present disclosure should not be construed as limited to secondary electron detection, but should be considered to encompass detection of secondary electrons and / or backscattered electrons.

[0033] In addition, in some embodiments, one or more of the electro-optical elements 112a may include a deflector stack, with one or more deflectors incorporated therein. For example, the deflector may be an octupole deflector (e.g., having eight plates), a quadrupole deflector (e.g., having four plates), or the like. Furthermore, in some embodiments, the deflector stack may include one or more deflector layers, with one or more deflectors incorporated within the deflector layers. For example, one or more pairs of deflectors may be incorporated within the deflector layers. For example, one or more pairs of octupole deflectors, one or more pairs of quadrupole deflectors, or a combination of one or more pairs of octupole deflectors and one or more pairs of quadrupole deflectors may be incorporated within the deflector layers. In some embodiments, the deflection ratio of the deflector layers may be used to quantify the deflection aberration associated with a pair of deflectors.

[0034] In addition, in the embodiment, the electron optical column 110a has one or more voltage lines corresponding to the number of deflectors in the electron optical column 110a. For example, if the one or more electron optical elements 112a include four octupole deflectors, the electron optical column 110a has 32 voltage lines for the four octupole deflectors. In the embodiment, the deflectors in the one or more electron optical elements 112a form deflector pairs or deflection layers depending on the operating voltage.

[0035] Additionally, in embodiments, the deflection layer includes an upper deflector 202 and a lower deflector 204. Furthermore, in embodiments, the upper deflector 202 and the lower deflector 204 are configured to perform one or more of two-stage deflection and / or dynamic astigmatism correction. Additionally, in embodiments, the upper deflector 202 and the lower deflector 204 have a selected thickness that allows two-stage deflection while applying the same voltage to the upper deflector 202 and the lower deflector 204. For example, if the upper deflector 202 and the lower deflector 204 are octupole deflectors, 16 voltage lines would be required. It should be noted that a deflector pair including the upper deflector 202 and the lower deflector 204 can be considered a deflector layer for purposes of this disclosure.

[0036] Also within the deflection layer, in embodiments, are upper trim deflectors 206 and lower trim deflectors 208. Furthermore, in embodiments, the upper trim deflectors 206 and lower trim deflectors 208 are configured to perform one or more of static deflection, static astigmatism correction, dynamic deflection, and / or dynamic astigmatism correction. It is noted that the deflector layer within which the upper trim deflectors 206 and lower trim deflectors 208 reside can be considered a trim deflector layer for purposes of this disclosure.

[0037] Additionally, in embodiments, upper deflector 202 is coupled to one or more amplifiers 210. Additionally, in embodiments, lower deflector 204 is coupled to one or more amplifiers 212. Additionally, in embodiments, upper trim deflector 206 is coupled to one or more amplifiers 214. Additionally, in embodiments, lower trim deflector 208 is coupled to one or more amplifiers 216.

[0038] For example, by appropriately designing the deflector layers and trim deflector layers, the resulting deflection can exceed the individual capabilities of the deflectors 202, 204, 206, and 208 and their corresponding amplifiers 210, 212, 214, and 216. Stacking multiple deflector layers in this manner can combine deflections, thereby increasing the amount of deflection achievable by one or more electron-optical elements 112a in the electron-optical column 110a. Therefore, the above description should be considered merely as illustrative and not as a limitation on the scope of the present disclosure.

[0039] According to another example, the deflector layer containing the upper deflector 202 and the lower deflector 204 can be operated at a high voltage, and the trim deflector layer containing the upper trim deflector 206 and the lower trim deflector 208 can be operated at a low voltage. In this example, the upper deflector 202 and the lower deflector 204 can be considered a high-voltage deflector pair for purposes of this disclosure. Additionally, in this example, the upper trim deflector 206 and the lower trim deflector 208 can be considered a low-voltage deflector pair for purposes of this disclosure. However, it is noted that the trim deflector layer containing the upper trim deflector 206 and the lower trim deflector 208 can be operated at a voltage higher than that of the deflector layer containing the upper deflector 202 and the lower deflector 204. Therefore, the above description should be taken as merely illustrative, and not as a limitation on the scope of the present disclosure.

[0040] 1 and 2, in embodiments where electron optical column array 108 includes electron optical columns 110a, 110b, 110c, and 110d, splitting the voltages for the high and low deflectors can reduce the number of electrical components in electron optical column array 108. For example, if upper deflector 202 is an octupole deflector, the per-plate signals for upper deflector 202 in electron optical column 110a can be utilized and / or driven by one common controller or common amplifier 210, and thus a total of eight amplifiers 210 or common controllers can be coupled to each of the upper deflectors 202 in electron optical columns 110b, 110c, and 110d. In another example, if the lower deflector 204 is an octupole deflector, the plate-by-plate signals of the lower deflectors 204 in one or more electron optical columns 110a can be utilized and / or driven by one common controller or common amplifier 212, and thus a total of eight amplifiers 212 or common controllers can be coupled to each lower deflector 204 of the electron optical columns 110b, 110c, and 110d.

[0041] It is noted that the use of common amplifiers for each individual deflector plate of the upper deflector 202 and the lower deflector 204 is possible due to the non-common static configuration and / or the division of a portion of the dynamic deflection into the trim deflector layers. For example, each plate of the upper trim deflector 206 can be individually driven and / or individually adjusted by a controller or amplifier 214, such that the number of controllers or amplifiers 214 included in the electron optical columns 110a, 110b, 110c, and 110d corresponds to the number of plates in the upper trim deflector 206. As another example, each plate of the lower trim deflector 208 can be individually driven and / or individually adjusted by a controller or amplifier 216, such that the number of controllers or amplifiers 216 included in the electron optical columns 110a, 110b, 110c, and 110d corresponds to the number of plates in the lower trim deflector 208.

[0042] Additionally, it is noted that the amplifiers 210, 212 and corresponding connectors coupled to the upper and lower deflectors 202, 204, respectively, may be larger (e.g., due to higher operating voltages) than the amplifiers 214, 216 and corresponding connectors coupled to the upper and lower trim deflectors 206, 208, respectively. Additionally, it is noted that the smaller amplifiers 214, 216 may be more tightly routed, cabled, and / or packaged and may consume less power than the larger amplifiers 210, 212.

[0043] In this regard, one or more amplifiers 210 or common controllers, and one or more amplifiers 212 or common controllers, coupled to the upper deflector 202 and the lower deflector 204, respectively, can operate as common drivers for the deflector layers containing the upper and lower deflectors 202 and 204 across one or more electron-optical columns 110a, 110b, 110c, and 110d in the electron-optical column array 108. Additionally, one or more amplifiers 214 or controllers, and one or more amplifiers 216 or controllers, coupled to the upper and lower trim deflectors 206 and 208, respectively, can operate as smaller individual drivers for the trim deflector layers containing the upper and lower trim deflectors 206 and 208 for the purpose of finely adjusting one or more secondary electron beams 118a, 118b, 118c, and 118d. Thus, the overall volume, complexity, and power consumption of the present SEM-based characterization tool 100 may be reduced.

[0044] Although embodiments of the present disclosure are directed to coupling upper deflector 202 and lower deflector 204 to amplifiers 210 and 212, respectively, it is noted that upper deflector 202 and lower deflector 204 may be coupled to a single common set of amplifiers, in which case upper deflector 202 and lower deflector 204 may be commonly coupled across electron optical columns 110a, 110b, 110c, and 110d. Therefore, the above description should be taken as merely illustrative and not as a limitation on the scope of the present disclosure.

[0045] 2, in some embodiments, the deflector layers and trim deflector layers are arranged to define an electron beam channel having a selected shape and centered on an axis passing through one or more electron optical elements 112a of the electron optical column 110a. For example, the shape of the electron beam channel may be selected to improve (e.g., increase and / or maximize) the deflection sensitivity of the electron optical column 110a without affecting (e.g., decreasing and / or reducing) the collection of the secondary electron beams 118a or other secondary electron beams 118a. For example, the shape may be selected to improve deflection sensitivity by directing one or more secondary electron beams 118a as close as possible to one or more electron optical elements 112a without colliding with the electron optical element(s) 112a. It is noted that improving the deflection sensitivity of the electron optical column 110a without affecting the collection of the secondary electron beam 118a is important for low voltage deflector pairs.

[0046] In another example, the electron beam channel may be conical, with a narrow end and a wide end, and the conical electron beam channel may be formed via one or more design constraints on one or more electron optical elements 112a within the electron optical column 110a.

[0047] For example, the conical electron beam channel can be formed by a conical aperture in one or more of the electron optical elements 112 a. The conical aperture can be defined by an inner surface of the one or more electron optical elements 112 a, particularly an inner surface that is tilted / beveled with respect to an angle from a central axis passing through the one or more electron optical elements 112 a. One or more of the upper deflector 202, the lower deflector 204, the upper trim deflector 206, and / or the lower trim deflector 208 can have a tilted / beveled inner surface.

[0048] Additionally, the conical electron beam channel can be formed by an inner surface of the first electron optical element 112 a and an inner surface of at least one additional electron optical element 112 a. The inner surfaces of the first electron optical element 112 a and the at least one additional electron optical element 112 a can each be located at a selected distance (e.g., different selected distances or the same selected distance) from a central axis passing through the electron optical element 112 a. One or more of the upper deflector 202, the lower deflector 204, the upper trim deflector 206, and / or the lower trim deflector 208 can have an inner surface located at a selected distance from its central axis.

[0049] Furthermore, the conical electron beam channel can be formed by a combination of conical openings in the electron optical element 112a and by an inner surface of the first electron optical element 112a and at least one additional electron optical element 112a located at a selected distance from the central axis.

[0050] According to another example, the shape of the electron beam channel can be tailored to the components of the SEM-based characterization tool 100. For example, the narrow end of the channel can be tailored to the size of one or more secondary electron beams 118a. Additionally, the wide end of the channel can be tailored to the size of one or more secondary electron detectors 200.

[0051] Additionally, in embodiments, the upper deflector 202, the lower deflector 204, the upper trim deflector 206, and / or the lower trim deflector 208 may be spaced apart within the deflector stack of the electron optical column 110a to compensate for the deflection ratio. For example, the upper deflector 202 and the upper trim deflector 206 may be spaced apart to compensate for the deflection ratio.

[0052] According to another example, the spacing between one or more of the upper deflector 202, the lower deflector 204, the upper trim deflector 206, and / or the lower trim deflector 208 can be increased or decreased to compensate for the deflection ratio.

[0053] For example, one or more primary electron beams 106a can be directed into the upper deflector 202, the upper trim deflector 206, the lower trim deflector 208, and the lower deflector 204 of the deflector stack, in that order. Additionally, one or more secondary electron beams 118a can be directed into the deflector stack, e.g., the lower deflector 204, the lower trim deflector 208, the upper trim deflector 206, and the upper deflector 202, in that order. It is noted that locating the upper deflector 202 and the lower deflector 204 at the top and bottom of the deflector stack can improve (e.g., increase and / or maximize) the deflection arm over a given length of the electron optical column 110a. This, in turn, can reduce and / or minimize the deflection (e.g., kick) of the primary electron beam 106 a at the lower deflector 204 over a selected deflection length of one or more secondary electron beams 118 a. Reducing and / or minimizing the deflection (e.g., kick) of one or more primary electron beams 106 a traveling forward through one or more electron optical elements 112 a at the lower deflector 204 can in turn reduce and / or minimize the deflection of one or more secondary electron beams 118 a traveling backward through the same one or more electron optical elements 112 a. In this regard, the deflection of the secondary electron beams 118 a that results in a signal at one or more secondary electron detectors 200 can be increased and / or maximized.

[0054] According to another example, the thickness of one or more of the upper deflector 202, the lower deflector 204, the upper trim deflector 206, and / or the lower trim deflector 208 can be increased or decreased to compensate for the deflection ratio. For example, by providing the upper deflector 202, the lower deflector 204, the upper trim deflector 206, and / or the lower trim deflector 208 with a selected thickness, the upper deflector 202 and the lower deflector 204 can be significantly thinner (e.g., thinner, flatter, or lower profile) than the upper trim deflector 206 and the lower trim deflector 208. The upper deflector 202 and the lower deflector 204 can be operated at a higher voltage, even if they are thinner. In contrast, the upper trim deflector 206 and the lower trim deflector 208 would substantially fill the space of their deflector stack (and the space of the electron optical column 110a more generally) to take advantage of the low voltages provided. It is noted, however, that the upper deflector 202 and the lower deflector 204 may be the same thickness as or greater than the upper trim deflector 206 and / or the lower trim deflector 208. Therefore, the above description should be taken as merely illustrative and not as a limitation on the scope of the present disclosure.

[0055] It is noted that any of the presented examples can be combined to compensate for the deflection ratio. Therefore, the above description should not be taken as a limitation on the scope of the present disclosure, but merely as an illustration.

[0056] In some embodiments, the one or more electron-optical elements 112a include one or more objective lenses 218. For example, but not limited to, a dynamic focus (DF) lens may be included in the one or more objective lenses 218. For example, a DF lens, such as a weak adjustable lens, may be configured to keep the one or more primary electron beams 106a in focus during side-scanning of the specimen 114, thereby compensating for focal height variations. In other embodiments, the one or more objective lenses 218 may include, but are not limited to, a bottom pole (LP) lens. For example, a LP lens, such as a decelerating magnetic immersion lens, may be configured to provide a selected level of electron-optical performance during scanning while providing a long working distance relative to the specimen 114. In some embodiments, the one or more primary electron beams 106a are directed into the one or more objective lenses 218 through the deflector stack.

[0057] Also, in embodiments, misalignment of the electron optical column 110a may be adjusted (or corrected) using the deflector stack. For example, a two-stage deflection process may be used to adjust (or correct) a small misalignment of the electron optical column 110a, thereby steering the beam within one or more of the objective lenses 218 on the central axis to be parallel to the central axis. For example, a single-stage deflection process may be used to adjust a large misalignment of the electron optical column 110a, thereby steering the beam within one or more of the objective lenses 218 on the central axis to be at an angle.

[0058] In an embodiment, one or more primary electron beams 106 a are directed toward the specimen 114 by a conical electron beam channel of an electron optical column 110 a included in the SEM-based characterization tool 100. For example, the one or more primary electron beams 106 a may travel within the electron optical channel of the electron optical column 110 a. The one or more primary electron beams 106 a may be double deflected by an upper deflector 202 and a lower deflector 204. The one or more primary electron beams 106 a may be dynamically astigmatized by a lower trim deflector 208. The one or more primary electron beams 106 a may be statically astigmatized and / or deflected by an upper trim deflector 206 and a lower trim deflector 208. One or more objective lenses 218 can direct one or more primary electron beams 106a onto the specimen 114, thereby generating one or more secondary electron beams 118a from backscattered and / or emitted electrons from the one or more primary electron beams 106a, thereby improving the spot size at the specimen 114 over the field of view.

[0059] In an embodiment, one or more secondary electron beams 118 a are directed to one or more secondary electron detectors 200 by a conical electron beam channel of an electron optical column 110 a included in the SEM-based characterization tool 100. For example, the one or more secondary electron beams 118 a can be directed backward within the electron optical channel of the electron optical column 110. As an example, the one or more secondary electron beams 118 a can be deflected by a lower deflector 204 to cause the one or more secondary electron beams 118 a to travel parallel to the shape of the electron beam channel through the deflector stack (e.g., parallel to the conical surface), thereby improving the deflection field of view.

[0060] It is noted that the present disclosure is not limited to using multiple sets of electron optical deflectors in common and individual modes within the electron optical column of an SEM-based characterization tool. For example, multiple sets of optical deflectors may be used in common and individual modes within a characterization tool. Therefore, the above description should be taken as merely illustrative and not as a limitation on the scope of the present disclosure.

[0061] While this disclosure focuses generally on multi-column SEM-based characterization tools, the scope of this disclosure should not be construed as being limited to such configurations. Rather, it is recognized that various embodiments of this disclosure can be extended to any type of electronic characterization tool, including, but not limited to, secondary electron (SE)-based characterization tools, multi-beam SEM-based characterization tools, etc.

[0062] Although this disclosure focuses generally on electronic characterization tools, the scope of this disclosure should not be construed as being limited to such configurations, but rather, it is recognized that various embodiments of this disclosure can be extended to any type of characterization tool known in the art, including, but not limited to, focused ion beam (FIB) characterization tools and optical characterization tools.

[0063] FIG. 3 depicts a simplified schematic representation of an optical characterization tool 300 according to one or more embodiments of the present disclosure.

[0064] Optical characterization tool 300 according to embodiments may include any optical characterization tool known in the art, including, but not limited to, optical characterization tools operable at wavelengths corresponding to visible light, UV radiation, DUV radiation, VUV radiation, EUV radiation, and / or X-ray radiation.

[0065] In addition, the optical characterization tool 300 according to an embodiment includes a radiation source array 302. Furthermore, in an embodiment, the radiation source array 302 includes one or more radiation sources. For example, the radiation source array 302 can include, but is not limited to, a first radiation source 304a, a second radiation source 304b, a third radiation source 304c, and / or at least a fourth radiation source 304d.

[0066] In addition, the optical characterization tool 300, in accordance with an embodiment, includes an optical column array 308. Furthermore, in an embodiment, the optical column array 308 includes one or more optical columns. For example, the optical column array 308 can include, but is not limited to, a first optical column 310a, a second optical column 310b, a third optical column 310c, and / or at least a fourth optical column 310d.

[0067] In embodiments, one or more primary radiation beams are generated by one or more radiation sources. For example, primary radiation beams 306a, 306b, 306c, and 306d may be generated by radiation sources 304a, 304b, 304c, and 304d. In embodiments, one or more primary radiation beams are directed toward one or more optical columns in optical column array 308. For example, one or more primary radiation beams 306a, 306b, 306c, and 306d may be directed toward optical columns 310a, 310b, 310c, and 310d in optical column array 308. In some embodiments, one or more source optical elements in illumination beam source array 302 split and direct the radiation beams generated by one or more radiation sources toward two or more optical columns in optical column array 308.

[0068] In some embodiments, the one or more optical columns may include one or more optical elements. For example, optical columns 310a, 310b, 310c, and 310d may include optical elements 312a, 312b, 312c, and 312d. Alternatively, the one or more optical elements may include, but are not limited to, a light deflector layer, a light trim deflector layer, or the like. For example, one or more of the light deflector layer or the light trim deflector layer may include one or more optical deflectors, such as, but not limited to, one or more prisms, one or more acousto-optic modulators, or the like.

[0069] In some embodiments, one or more optical deflectors in the optical deflection layer are configured to perform one or more of two-stage deflection and / or dynamic astigmatism correction. In some embodiments, one or more optical trim deflectors are present in the optical trim deflector layer. In some embodiments, the optical trim deflectors in the optical trim deflector layer are configured to perform one or more of static deflection, static astigmatism correction, dynamic deflection, and / or dynamic astigmatism correction.

[0070] Also, in embodiments, the light deflector layer operates at a high voltage and the light trim deflector layer operates at a low voltage. However, it is noted that the light trim deflector layer may operate at a voltage higher than that of the light deflector layer. Therefore, the above description should not be construed as a limitation on the scope of the present disclosure, but merely as an example.

[0071] Additionally, in embodiments, one or more light deflectors in the light deflector layer of an optical column (e.g., optical column 310a) are coupled to an amplifier or common controller, and a select number of amplifiers are coupled to light deflectors in the light deflector layers of additional optical columns (e.g., optical columns 310b, 310c, 310d) in the optical column array 308. It is noted that the use of a common amplifier for each individual light deflector is due to its static configuration and / or the division of a portion of the dynamic deflection to the optical trim deflector layers. For example, the optical trim deflectors in the optical trim deflector layers can be individually driven and / or individually adjusted by a controller or amplifier in a particular optical column (e.g., optical column 310a, 310b, 310c, 310d) in the optical column array 308.

[0072] It is noted that the amplifiers and corresponding connectors coupled to the light deflectors in the light deflector layer may be larger (e.g., due to higher operating voltages) than the amplifiers and corresponding connectors coupled to the light trim deflectors in the light trim deflector layer. In addition, it is noted that smaller amplifiers may be more tightly routed, cabled, and / or packaged and consume less power than larger amplifiers.

[0073] In this case, one or more amplifiers or common controllers coupled to the light deflectors in the light deflector layer can operate as common drivers for the light deflectors in the light deflector layer across one or more optical columns (e.g., optical columns 310a, 310b, 310c, 310d) in the optical column array 308. Additionally, when one or more secondary radiation beams are generated by one or more primary radiation beams (e.g., primary radiation beams 306a, 306b, 306c, 306d) impinging on the specimen 314, one or more amplifiers or controllers coupled to the optical trim deflectors in the optical trim deflector layer can act as smaller individual drivers for the optical trim deflectors in the optical trim deflector layer of one or more optical columns (e.g., optical columns 310a, 310b, 310c, 310d) in the optical column array 108 to fine-tune one or more secondary radiation beams (e.g., secondary radiation beams 318a, 318b, 318c, 318d). Thus, the overall volume, complexity, and power consumption of the optical characterization tool 300 can be reduced.

[0074] In embodiments, the light deflector layers and light trim deflector layers are arranged to form a light beam channel of a selected shape, with the light beam channel centered on an axis passing through one or more optical elements (e.g., optical elements 312a, 312b, 312c, 312d) of one or more optical columns (e.g., optical columns 310a, 310b, 310c, 310d) of the optical column array 308. For example, the light beam channel may be conical in shape, with a narrow end and a wide end, and the conical light beam channel may be formed via one or more design constraints on one or more optical elements (e.g., optical elements 312a, 312b, 312c, 312d) of one or more optical columns (e.g., optical columns 310a, 310b, 310c, 310d) of the optical column array 308. As an example, the conical light beam channel can be formed by a conical aperture in one or more optical elements (e.g., optical elements 312a, 312b, 312c, 312d). The conical aperture can be defined by an inner surface of the one or more optical elements (e.g., optical elements 312a, 312b, 312c, 312d), particularly an inner surface that is tilted / beveled with respect to an angle from a central axis passing through the one or more optical elements (e.g., optical elements 312a, 312b, 312c, 312d). It is noted that all descriptions of the geometry and operation of electron beam channels passing through one or more electron optical columns (e.g., electron optical columns 110a, 110b, 110c, 110d) of electron optical column array 108 can, for purposes of this disclosure, be extended to optical beam channels passing through one or more optical columns (e.g., optical columns 310a, 310b, 310c, 310d) of optical column array 308. Accordingly, the above descriptions should be taken as merely illustrative and not as limitations on the scope of the present disclosure.

[0075] In embodiments, one or more optical columns in optical column array 308 direct one or more primary radiation beams toward sample 314, which is held on sample stage 316. For example, optical columns 310a, 310b, 310c, and 310d may direct primary radiation beams 306a, 306b, 306c, and 306d toward sample 314, which is held on sample stage 316. In embodiments, one or more radiation beams are generated at sample 314 in response to one or more primary radiation beams impinging on sample 314. For example, one or more secondary radiation beams 318a, 318b, 318c, and 318d may be generated at sample 314 in response to primary radiation beams 306a, 306b, 306c, and 306d impinging on sample 314.

[0076] In some embodiments, one or more optical columns may include one or more photodetectors. For example, one or more of optical columns 310a, 310b, 310c, and 310d may include one or more photodetectors. In some embodiments, one or more optical elements may direct one or more secondary radiation beams to one or more photodetectors in the optical columns. For example, optical elements 312a, 312b, 312c, and 312d may direct secondary radiation beams 318a, 318b, 318c, and 318d to one or more photodetectors in optical columns 310a, 310b, 310c, and 310d.

[0077] It is noted that all descriptions of specimen 114 may be extended to specimen 314. Additionally, it is noted that all descriptions of specimen stage 116 may be extended to specimen stage 316. Accordingly, the above descriptions should not be taken as limitations on the scope of the present disclosure, but merely as illustrations.

[0078] It is noted that, for purposes of this disclosure, any description of radiation beam 306a may be extended to radiation beams 306b, 306c, and 306d. Additionally, it is noted that, for purposes of this disclosure, any description of optical column 310a may be extended to optical columns 310b, 310c, and 310d. It is further noted that, for purposes of this disclosure, any description of one or more optical elements 312a may be extended to one or more optical elements 312b, 312c, and 312d. It is further noted that, for purposes of this disclosure, any description of secondary radiation beam 318a may be extended to secondary radiation beams 318b, 318c, and 318d. Accordingly, the foregoing description should be taken as merely illustrative and not as a limitation on the scope of the present disclosure.

[0079] FIG. 4 depicts a characterization system 400 according to one or more embodiments of the present disclosure.

[0080] The characterization system 400 according to an embodiment includes a characterization tool 402. The characterization system 400 may incorporate any suitable characterization tool 402 known in the art. In general, the characterization tool 402 may include any suitable characterization tool for characterizing one or more photomasks / reticles or wafers.

[0081] In embodiments, characterization tool 402 includes one or more characterization tools and / or characterization components configured to characterize one or more photomasks / reticles or wafers as known in the art. For example, characterization tool 402 may include, but is not limited to, SEM-based characterization tool 100, optical characterization tool 300, FIB-based characterization tool, etc. Generally, characterization tool 402 may include, but is not limited to, inspection tools, review tools, imaging-based overlay metrology tools, etc.

[0082] Additionally, in embodiments, characterization system 400 includes a controller 404. Moreover, in embodiments, controller 404 is operably coupled to one or more components of characterization tool 402. As such, controller 404 can direct any of the components of characterization tool 402 to perform any one or more of the functions described elsewhere in this disclosure.

[0083] In embodiments, controller 404 also includes one or more processors 406 and memory 408. In embodiments, memory 408 further includes a set of program instructions 410 stored therein. In embodiments, the set of program instructions 410 is configured to cause one or more processors 406 to perform any one or more process steps described elsewhere in this disclosure.

[0084] Controller 404 can be configured to receive and / or acquire data or information from tools or other systems within characterization tool 402 via a transmission medium, such as a wired and / or wireless link. Additionally, controller 404 can be configured to transmit data or information (e.g., output of one or more procedures of the inventive concepts described herein) to one or more systems or tools within characterization tool 402 via a transmission medium, such as a wired and / or wireless link, which can serve as a data link between controller 404 and other subsystems of characterization tool 402. Additionally, controller 404 can be configured to send data to external systems via a transmission medium (e.g., a network connection).

[0085] The one or more processors 406 may include any one or more processing elements known in the art. In this sense, the one or more processors 406 may include any microprocessor device configured to execute algorithms and / or program instructions. For example, the one or more processors 406 may comprise a desktop computer, a mainframe computer system, a workstation, an image computer, a parallel processor, a handheld computer (e.g., a tablet, smartphone, or phablet), or other computer system (e.g., a networked computer). In general, the term "processor" may be broadly defined to encompass any device having one or more processing elements that executes a set of program instructions 410 obtained from a non-transitory storage medium (e.g., memory 408). Furthermore, the various subsystems of the characterization tool 402 may incorporate processors or logic elements suitable for performing at least a portion of the steps described elsewhere in this disclosure. Therefore, the above description should be taken as merely illustrative, and not as a limitation on the scope of the present disclosure.

[0086] The memory 408 may include any storage medium known in the art suitable for storing a set of program instructions 410 executable by one or more processors 406 in cooperation therewith. For example, the memory 408 may include a non-transitory storage medium. Examples of the memory 408 include, but are not limited to, read-only memory (ROM), random access memory (RAM), magnetic or optical storage devices (e.g., disks), magnetic tape, solid-state drives, etc. The memory 408 may be configured to provide display information to a display device included in a user interface. Additionally, the memory 408 may be configured to store user input information from a user input device included in a user interface. The memory 408 may be housed within a common housing of the controller 404 along with one or more processors 406. Alternatively or additionally, the memory 408 may be located remotely relative to the spatial location of the processors 406 and / or the controller 404. As an example, one or more processors 406 and / or controllers 404 may access a remote memory 408 (eg, a server) accessible over a network (eg, the Internet, an intranet, etc.).

[0087] Also, in embodiments, data from one or more components of characterization tool 402 is read and / or processed by one or more sets of electronic circuitry coupled to controller 404 and / or software stored on controller 404. Furthermore, in embodiments, images generated by or on one or more components of characterization tool 402 are read and / or processed by one or more sets of electronic circuitry coupled to controller 404 and / or software stored on controller 404.

[0088] Additionally, in embodiments, the characterization system 400 includes a user interface. Further, in embodiments, the user interface is coupled (e.g., physically and / or communicatively coupled) to the controller 404. Further, in embodiments, the user interface includes a display device. Further, in embodiments, the user interface includes a user input device. Further, in embodiments, the display device is coupled to the user input device. For example, the display device can be coupled to the user input device via a transmission medium, such as a wired and / or wireless transmission medium.

[0089] Although embodiments of the present disclosure depict that the controller 404 may be coupled to or integrated within the characterization tool 402, the controller 404 is not an integral or required component of the characterization tool 402. Additionally, although embodiments of the present disclosure depict that the user interface may be coupled to or integrated within the controller 404, the user interface is not an integral or required component of the controller 404 or the characterization tool 402. Therefore, the foregoing description should be taken as merely illustrative, and not as a limitation on the scope of the present disclosure.

[0090] As those skilled in the art will recognize, the current state of the art has advanced to the point where there is little difference between hardware, software, and / or firmware implementations of the systems of the embodiments, and the use of hardware, software, and / or firmware is generally (but not always, as the choice between hardware and software can be critical in certain circumstances) a design choice representing a cost-efficiency trade-off. As those skilled in the art will recognize, there are various means (e.g., hardware, software, and / or firmware) by which the processes and / or systems and / or other technologies described herein can be implemented, and the appropriate means will vary depending on the context in which the processes and / or systems and / or other technologies are used. For example, if an implementer determines that speed and accuracy are essential, the implementer may select a primarily hardware and / or firmware implementation; if flexibility is otherwise essential, the implementer may select a primarily software implementation; and if neither of these is the case, the implementer may select some combination of hardware, software, and / or firmware. Thus, while there are several potential means by which the processes and / or apparatus and / or other technologies described herein may be implemented, none is inherently superior to the others, and the means to be utilized is a matter of choice governed by variables such as the circumstances in which the means is valued and the particular concerns of the implementer (e.g., speed, flexibility, or predictability). As those skilled in the art will recognize, the optical aspects of the embodiments will typically employ optically oriented hardware, software, and / or firmware.

[0091] In some implementations described herein, software or other control structures may be incorporated into logic implementations and the like. For example, one or more current paths in electronic circuits may be configured and arranged appropriately to implement various functions described herein. In some implementations, one or more media may be configured to carry device-detectable implementations when operable device-detectable instructions, executable as described herein, are carried or transmitted by the media. In some variations, for example, implementations may incorporate updates or modifications to existing software or firmware, or gate arrays or programmable hardware, such as by receiving or transmitting one or more instructions associated with one or more of the operations described herein. Alternatively or additionally, in some variations, implementations may incorporate dedicated hardware, software, or firmware components and / or general-purpose components that execute or otherwise invoke the dedicated components. Specifications and other implementations may be transmitted over one or more tangible transmission media as described herein, or may, but need not, be transmitted via packet transmission, or may be transmitted by delivery in a distributed medium at various times.

[0092] Alternatively or additionally, implementations may incorporate the execution of specialized instruction sequences or invocation of circuits to cause substantially any functional operation described herein to be realized, invoked, coordinated, requested, or otherwise performed one or more times. In some variations, operations and other logical descriptions herein may be expressed as source code and then compiled or otherwise invoked as executable instruction sequences. In some circumstances, for example, implementations may be provided in whole or in part as source code, e.g., C++ or other code sequences. In some implementations, source code or other code implementations may be compiled / embodied / translated / converted into a higher-level description language using commercially available technology in the art (e.g., by first embodying the described technology in the C, C++, Python™, Ruby on Rails™, Java™, PHP, .NET™, or Node.js™ programming languages ​​and then converting the programming language implementation into a logic synthesizable language implementation, a hardware description language implementation, a hardware design simulation implementation, and / or other similar representation mode(s). For example, some or all of the logic representations (e.g., computer programming language implementations) may be specified in a Verilog™-style hardware description (e.g., in a Hardware Description Language (HDL) and / or Very High Speed ​​Integrated Circuit Hardware Description Language (VHDL)) or other circuit model and then used to generate a tangible implementation in hardware (e.g., an application-specific integrated circuit). In light of these teachings, those skilled in the art will recognize how to obtain, configure, and optimize suitable transmission or information processing elements, material sources, actuators, and other structures.

[0093] In the foregoing detailed description, the apparatus, devices, and / or processes of various embodiments are described through the use of block diagrams, flowcharts, and / or examples. To the extent that the block diagrams, flowcharts, and / or examples include one or more functions and / or operations, those skilled in the art will understand that the functions and / or operations within the block diagrams, flowcharts, or examples, individually and / or collectively, can be implemented or performed by a wide variety of hardware, software, firmware, or substantially any combination thereof. According to certain embodiments, portions of the subject matter described herein may be implemented in an application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), digital signal processor (DSP), or other integrated form. However, those skilled in the art will recognize that some aspects of the presently disclosed embodiments can be equivalently implemented, in whole or in part, in integrated circuits, as one or more computer programs running on one or more computers (e.g., one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., one or more programs running on one or more microprocessors), as firmware, or virtually any combination thereof, and that designing such circuitry and / or writing such software and / or firmware code would be within the skill of those skilled in the art in light of this disclosure. Additionally, those skilled in the art will recognize that mechanisms of the presently described subject matter can be distributed as a program product in a variety of forms, and that exemplary embodiments of the presently described subject matter apply regardless of the particular type of signal-bearing medium used to actually effect such distribution.Examples of signal bearing media include, but are not limited to, recordable media such as floppy disks, hard disk drives, compact disks (CDs), digital video disks (DVDs), digital tape, computer memory, etc., and transmission media such as digital and / or analog communications media (e.g., fiber optic cables, waveguides, wired communications links, wireless communications links (e.g., transmitters, receivers, transmitting logic, receiving logic, etc.)).

[0094] In general, as will be appreciated by those skilled in the art, various embodiments described herein can be implemented, individually and / or collectively, by various types of electromechanical systems having a wide variety of electrical components, such as hardware, software, firmware, and / or nearly any combination thereof, and a wide variety of mechanical force or motion imparting components, such as rigid bodies, springs or torsion bodies, hydraulic drives, electromagnetic drives, and / or nearly any combination thereof. Accordingly, the term "electromechanical system" as used herein includes, but is not limited to, an electrical circuit operably coupled to a transducer (e.g., an actuator, motor, piezoelectric crystal, microelectromechanical system (MEMS), etc.), an electrical circuit having at least one discrete electrical circuit, an electrical circuit having at least one integrated circuit, an electrical circuit having at least one application specific integrated circuit, an electrical circuit forming a general purpose information processing device configured by a computer program (e.g., a general purpose computer configured by a computer program that at least partially performs or implements the processes and / or devices described herein, or a microprocessor configured by a computer program that at least partially performs or implements the processes and / or devices described herein), an electrical circuit forming a storage device (e.g., various forms of memory (e.g., random access, flash, read only, etc.)), an electrical circuit forming a communications device (e.g., a modem, communications switch, optoelectronic device, etc.), and / or non-electrical, e.g., optical or other, analogs thereof. As will be appreciated by those skilled in the art, examples of electromechanical systems include, but are not limited to, various consumer electronic systems, medical devices, and other systems, such as powered transportation systems, factory automation systems, security systems, and / or communication / information processing systems. As will be appreciated by those skilled in the art, electromechanical, as used herein, is not necessarily limited to systems with both electric and mechanical drives, unless the context states otherwise.

[0095] In general, as will be appreciated by those skilled in the art, the various aspects described herein may be individually and / or collectively implemented by a wide variety of hardware, software, firmware, and / or any combination thereof, and may be viewed as comprising various types of "electrical circuitry." Accordingly, "electrical circuitry," as used herein, includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application-specific integrated circuit, electrical circuitry forming a general-purpose information processing device configured by a computer program (e.g., a general-purpose computer configured by a computer program that at least partially executes or implements the processes and / or devices described herein, or a microprocessor configured by a computer program that at least partially executes or implements the processes and / or devices described herein), electrical circuitry forming a storage device (e.g., various forms of memory (e.g., random access, flash, read-only, etc.)), and / or electrical circuitry forming a communications device (e.g., a modem, a communications switch, a photoelectric device, etc.). As those skilled in the art will recognize, the subject matter described herein may be implemented in analog form, digital form, or any combination thereof.

[0096] As those skilled in the art will recognize, at least a portion of the devices and / or processes described herein can be integrated into a data processing system. As those skilled in the art will recognize, a data processing system typically includes one or more of the following: a system unit housing; a video display device; memory, such as volatile or non-volatile memory; a processor, such as a microprocessor or digital signal processor; information processing entities, such as an operating system, drivers, a graphical user interface, and application programs; one or more interactive devices (e.g., touchpad, touchscreen, antenna, etc.); and / or a control system having feedback loops and control motors (e.g., feedback for sensing position and / or velocity, control motors for moving and / or adjusting members and / or quantities). The data processing system can be implemented using suitable commercially available components, such as those commonly found in data information processing / communication and / or network information processing / communication systems.

[0097] As those skilled in the art will recognize, the components (e.g., operations), devices, objects, and accompanying discussion described herein are used as examples for conceptual clarity, and various configuration modifications are contemplated. Thus, as used herein, the specific exemplars described above and their accompanying discussion are intended to be representative of their more general class. In general, the use of any specific exemplar is intended to be representative of that class, and the absence of specific components (e.g., operations), devices, and objects should not be construed as a limitation.

[0098] Although user is described in the singular herein, those skilled in the art will appreciate that, unless the context dictates otherwise, user can represent a human user, a robotic user (e.g., a data processing entity), and / or substantially any combination thereof (e.g., a user may be assisted by one or more robotic agents). Those skilled in the art will appreciate that, generally, unless the context dictates otherwise, the same can be said of "sender" and / or other entity-oriented terms used herein.

[0099] With respect to the use of nearly all plural and / or singular terms herein, those skilled in the art will be able to translate from the plural to the singular and / or vice versa where appropriate given the context and / or application. For the sake of clarity, the various singular / plural permutations have not been explicitly set forth herein.

[0100] In some places, the subject matter described herein is depicted with various components embedded in or connected to various other components. It is understood that the illustrated architectures are merely exemplary, and in fact, many other architectures exist that achieve the same functionality. Conceptually, any arrangement of components that achieves the same functionality is substantially "associated" to achieve the desired functionality. Thus, any two components herein that are combined to achieve a particular function can be considered to be "associated" with each other to achieve the desired functionality, regardless of the architecture or intervening components. Similarly, any two components so associated can also be viewed as "operably connected" or "operably coupled" to each other to achieve the desired functionality, and any two components that can be so associated can also be viewed as "operably connectable" to each other to achieve the desired functionality. Examples of operably coupleable include, but are not limited to, physically coupleable and / or physically interacting elements, and / or wirelessly interactable and / or wirelessly interacting elements, and / or logically interacting and / or logically interacting elements, etc.

[0101] In some cases, one or more elements may be referred to herein as "configured to," "configurable to," "operable / able to," "adapted / adaptable," "may," "can be / are adapted to," etc. As those skilled in the art will recognize, unless the context requires otherwise, these terms (e.g., "configured to") can generally encompass active state elements and / or inactive state elements and / or standby state elements.

[0102] While specific aspects of the subject matter disclosed herein have been shown and described, those skilled in the art will recognize that changes and modifications can be made based on the teachings herein without departing from the subject matter disclosed herein and its broader aspects, and that all such changes and modifications are intended to be encompassed within the scope of the appended claims as being within the true spirit and scope of the subject matter disclosed herein. As those skilled in the art will recognize, generally, the terms used in this application, particularly in the appended claims (e.g., the body of the appended claims), are generally intended to be "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "including" should be interpreted as "including but not limited to," etc.). As those skilled in the art will also recognize, if a specific number of elements are intended to be included in a claim, that intention will be clearly stated in the claim, and the absence of such elements indicates no intention. For example, as an aid to understanding, some of the appended claims below include the introduction of claim features by the introductory phrases "at least one" and "one or more." However, the use of such phrases should not be construed as implying that the introduction of a claim feature with the indefinite article "a" or "an" limits all individual claims containing that claim feature to containing only one of that feature, even when the introductory phrase "one or more" or "at least one" coexists with an indefinite article, such as "a" or "an" in the very same claim (e.g., "a" and / or "an" should generally be understood to mean "at least one" or "one or more"), nor should this be construed as implying that the introduction of a claim feature with the indefinite article "a" or "an" implies that all individual claims containing that claim feature are limited to containing only one of that feature. In addition, even if a specific number of elements are explicitly stated in a claim, as would be recognized by a person skilled in the art, the stated number should normally be interpreted to mean at least the stated number (e.g., the bare expression "two elements" without any other modifiers normally means at least two elements or more than two elements).Furthermore, where a convention similar to "at least one of A, B, and C, etc." is used, such syntax is generally intended to align with how a person skilled in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or systems having A, B, and C, etc.). Where a convention similar to "at least one of A, B, or C, etc." is used, such syntax is generally intended to align with how a person skilled in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or systems having A, B, and C, etc.). As will also be understood by those skilled in the art, disjunctive conjunctions and / or disjunctive phrases, which typically present two or more alternative terms, whether appearing in the specification, claims, and drawings, should be understood to contemplate the inclusion of either, either, or both terms, unless the context clearly dictates otherwise. For example, the phrase "A or B" would typically be understood to encompass the possibilities of "A" or "B" or "A and B."

[0103] In the context of the appended claims, those skilled in the art will appreciate that the actions recited therein may generally be performed in any order. Additionally, while various action flows are presented in sequence(s), it should be understood that the various actions may be performed in an order different from that depicted, or may be performed simultaneously. Examples of such alternative orders may include overlapping, interpolating, interleaving, reordering, incremental, preparatory, additional, simultaneous, reversal, and other variable orders, unless the context dictates otherwise. Furthermore, the use of terms such as "according to," "related to," and other similar past tense adjectives is generally not intended to exclude such variations, unless the context dictates otherwise.

[0104] While specific embodiments of the present invention have been illustrated and described, it will be apparent that those skilled in the art may effect various modifications and embodiments of the present invention without departing from the scope and spirit of the foregoing disclosure. The present disclosure and many of its attendant advantages will be understood from the foregoing description, and it will also be apparent that various changes can be made in the form, configuration and arrangement of the parts without departing from the disclosed subject matter or diminishing all of its essential advantages. The described embodiments are merely illustrative, and it is the intent of the following claims to encompass and embrace all such modifications. The scope of the present invention, therefore, is to be limited only by the appended claims.

Claims

1. 1. A scanning electron microscopy (SEM) system comprising: a plurality of electron beam sources, at least some of which are configured to generate a primary electron beam; and an electron optical column array including a plurality of electron optical columns, wherein an electron optical column of the plurality of electron optical columns a plurality of electron optical elements arranged to form a conical electron beam channel, the conical electron beam channel configured to direct the primary electron beam at a specimen held on a stage, the specimen emitting an electron beam in response to the primary electron beam; and the conical electron beam channel having at least one electron detector configured to direct the electron beam toward the at least one electron detector; and deflecting the electron beam by at least one electron optical element of the plurality of electron optical elements to travel parallel to a conical surface of the conical electron beam channel and directing the electron beam toward the at least one electron detector; system.

2. 2. The system of claim 1, wherein the conical electron beam channel is formed by a conical aperture in at least one of the plurality of electron optical elements.

3. 2. The system of claim 1, wherein the conical electron beam channel is formed by an inner surface of a first electron optical element and an inner surface of at least one additional electron optical element of the plurality of electron optical elements, the inner surface of the first electron optical element and the inner surface of the at least one additional electron optical element being each located a selected distance from a central axis passing through the plurality of electron optical elements, and at least one of the inner surface of the first electron optical element and the inner surface of the at least one additional electron optical element including an inner surface that is sloped based on an angle relative to the central axis passing through the plurality of electron optical elements.

4. 4. The system of claim 3, wherein the selected distance from the central axis to the inner surface of the first electron-optical element is different from the selected distance from its central axis to the inner surface of the at least one additional electron-optical element.

5. 2. The system of claim 1, wherein the conical electron beam channel is formed by a conical aperture in at least one electron optical element of the plurality of electron optical elements together with an inner surface of a first electron optical element of the plurality of electron optical elements and an inner surface of at least one additional electron optical element; A system wherein the inner surfaces of the first electron-optical element and the at least one additional electron-optical element are each located a selected distance from a central axis passing through the plurality of electron-optical elements.

6. 10. The system of claim 1, wherein the conical electron beam channel narrows as the primary electron beam approaches the specimen.

7. 7. The system of claim 6, wherein the narrow opening of the conical electron beam channel is sized to fit the electron beam.

8. 2. The system of claim 1, wherein the conical electron beam channel widens as the electron beam moves toward the at least one electron detector.

9. 9. The system of claim 8, wherein a wide aperture of said conical electron beam channel is sized to fit said at least one electron detector.

10. 10. The system of claim 1, wherein the plurality of electron-optical elements comprises one or more objective lenses.

11. 1. An electro-optical system comprising: an electron optical column array having a plurality of electron optical columns, one of the plurality of electron optical columns having a plurality of electron optical elements arranged to form a conical electron beam channel, the conical electron beam channel configured to direct a primary electron beam at a specimen held on a stage, the specimen emitting an electron beam in response to the primary electron beam; and a conical electron beam channel configured to direct the electron beam to the at least one electron detector, the conical electron beam channel being deflected by at least one electron optical element of the plurality of electron optical elements to cause the electron beam to travel parallel to a conical surface of the conical electron beam channel and be directed to the at least one electron detector;

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