Monolithic perforated plate for multi-beam electron beam system

Abstract

A monolithic perforated plate for forming a plurality of electron beams of a multi-beam electron beam system is described. The monolithic perforated plate is composed of a monolithic construction element having individual functional planes and having a plurality of pores. In addition to the plurality of pores, the monolithic porous plate does not contain cavities. The monolithic porous plate design is used for better performance and longer service life.

Description

Technical Field

[0001] This invention relates to a porous plate for forming multiple electron beams in a multi-beam electron beam system. Background Technology

[0002] With the continuous development of smaller and more complex microstructures such as semiconductor components, there is a need to further develop and optimize planar generation technologies and inspection systems for inspecting small-sized microstructures. Therefore, there is a need for an inspection component that can be used at high throughput to inspect microstructures on wafers with high precision.

[0003] Typical silicon wafers used to fabricate semiconductor components can reach diameters of up to 300 millimeters (mm). Each wafer is subdivided into repeating regions (“bare dies”). A semiconductor device comprises several semiconductor structures fabricated in multiple layers on the surface of the wafer using planar integration techniques. Due to the fabrication process, semiconductor wafers typically have planar surfaces. The structural dimensions of integrated semiconductor structures in this case range from a few micrometers to a critical dimension (CD) of 5 nanometers (nm), and in the near future, these dimensions will become even smaller; in the future, the structural dimensions, or critical dimensions (CD), are expected to be less than 3 nanometers, for example, 2 nanometers, or even less than 1 nanometer. For a variety of applications, the specifications for the measurement accuracy provided by inspection equipment are even higher, for example, twice or an order of magnitude. For example, the width of semiconductor features must be measured with an accuracy better than 1 nm, for example, 0.3 nm or even smaller, and the relative positions of semiconductor structures must be determined with an overlap accuracy better than 1 nm (e.g., 0.3 nm or even smaller).

[0004] Multi-beam electron beam systems are a relatively recent development in the field of charged particle microscopy (“charged particle microscopy”). For example, multi-beam electron beam systems are disclosed in US 7 244 949 B2 and US 2019 / 0355544 A1. In the case of a multi-beam electron beam system or MSEM, multiple individual electron beams configured in a field or grating simultaneously irradiate the sample. For example, 4 to 10,000 individual electron beams can be provided as a primary radiation, with each individual electron beam separated from adjacent individual electron beams by a spacing of 1 to 200 micrometers. For example, a multi-beam electron beam system has approximately 100 separate individual electron beams (“small beams”), configured, for example, in a hexagonal grating, with the individual electron beams separated by a spacing of approximately 10 μm. Multiple individual charged particle beams (primary beams) are focused onto the surface of the sample to be examined through a common objective lens. For example, the sample can be a semiconductor wafer fixed to a wafer carrier mounted on a movable platform. When a wafer surface is irradiated by a primary beam of charged particles, interaction products, such as secondary electrons or backscattered electrons, are emitted from the wafer surface. The starting points correspond to the locations on the sample where, in each case, multiple primary beams are focused. The amount and energy of the interaction products depend particularly on the material composition and the wafer surface layout. These interaction products form multiple secondary beams, which are focused by a common objective and imaged onto a detector positioned in the detection plane by a projection imaging system of a multi-beam electron system. The detector comprises multiple detection regions, each containing multiple detection pixels, and captures the intensity distribution of each of the secondary beams. In this process, an image field of, for example, 100 μm × 100 μm is obtained.

[0005] State-of-the-art multi-beam electron beam systems consist of a series of electrostatic and magnetic components. At least some of these components are adjustable to tailor the focal positions and stigmation of the multiple individual charged particle beams. State-of-the-art multi-beam systems with charged particles also include at least one intersecting plane of the primary or secondary individual charged particle beams. Furthermore, state-of-the-art systems include a detection system to facilitate adjustment. State-of-the-art multi-beam electron beam systems include at least one beam deflector (“deflection scanner”) for focused scanning of a region of the sample surface by multiple individual primary particle beams to obtain an image field of the sample surface.

[0006] In state-of-the-art multi-beam electron beam systems, a first porous plate or filter plate with multiple first apertures in a first grating configuration is used to generate multiple individual beams. These individual beams then pass through additional porous plates, such as a second porous plate with a second aperture, for example, an array of active electrostatic elements. In typical examples, in addition to the first and second porous plates, there are additional porous plates with different apertures. Examples of this configuration of porous plates are disclosed in US 11,238,054 BB, US 2022392734 AA, and WO23016678 A1. In this case, the adjustment of the multiple individual porous plates requires special measures. Furthermore, during the operation of a multi-beam microscope, individual thin porous plates may deform. For example, this results in at least one individual beam no longer passing through the second aperture of the second porous plate from the center. Therefore, the fabrication and connection of the individual porous plates are very prone to errors. It is well known that surfaces with insulating materials can locally accumulate charge. To avoid this, recesses or cavities are typically formed to protect the insulating surface, thereby reducing the likelihood of the electron beam impacting the insulating material. Several examples are shown in US7,276,707 B2, in which the electrodes are separated from the multipole element by a vacuum gap. JP2816849 also shows a vacuum gap in a tortuous form or with a cross-sectional shape resembling the letter S. Other cross-sectional shapes are known from various sources, such as US 5,041,731, US 5,401,974, and US 6,055,719.

[0007] Other solutions (such as the solution in US 20200203114 A1) provide vacuum gaps between individual components of the porous plate. During operation, contaminants can accumulate in these vacuum gaps, potentially causing electrical short circuits.

[0008] DE 10 2022 131 862; "Programmable aperture plate for maskless high-throughput nanolithography" proposed by A1, IL Berry et al., Journal of Vacuum Science and Technology B 15 (1997), pp. 2382-2386; DE 10 2008 010123 A1; "Characterization of CMOS programmable multi-beamblanking arrays as used for programmable multi-beam projection lithography adresistless nanopatterning" proposed by S. Eder-Kapl et al., Journal of Micromechanics and Microengineering 21 (2011), pp. 045038.1-8; and US 2005 / 0 242 302 A1 discloses the background technology of multi-beam particle beam systems with perforated plates. Summary of the Invention

[0009] Therefore, one object of the present invention is to provide an improved multi-aperture configuration for generating or forming multiple electron beams for a multi-beam electron beam system, which is suitable for the increased resolution and accuracy requirements when performing wafer inspection tasks.

[0010] This objective is achieved by the independent claims. The dependent claims relate to advantageous embodiments. This patent application claims priority to German Patent Application No. 10 2023 126 510.5, filed on September 28, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0011] An improved multi-aperture configuration according to an embodiment of the present invention is provided by a monolithic porous plate for a multi-beam electron beam system. The monolithic porous plate includes a plurality of holes forming a continuous connection between a first or top side and a second or bottom side of the monolithic porous plate. Apart from the holes, the monolithic porous plate has no gaps or cavities, as contaminants would accumulate in these gaps or cavities, making operation in a vacuum more difficult. The monolithic porous plate is primarily composed of a first conductive material and a second insulating material. In one example, the monolithic porous plate is formed monolithically from the first conductive material, the second insulating material, and the absorber layer, without any separation points or cavities (other than the plurality of holes). Alternatively, a thin metal layer may also be present on the inner surface of the holes. However, in this case, more than 95% of the monolithic porous plate is composed of the first conductive material (e.g., doped silicon or polycrystalline silicon) and the second insulating material (e.g., silicon dioxide). The monolithic porous plate is not constructed by stacking individual porous plates, thus eliminating the need for error-prone adjustments and connections. Therefore, multiple functional layers can be integrated, such as more than two or three functional layer sequences. At least the first and second functional layer sequences are formed from first and second materials, each sequence comprising an active functional layer with multiple embedded electrodes, at least one connection layer with multiple electrical connection channels, and a passive functional layer. In one example, the active functional layer of the monolithic porous plate is formed as a multi-electrode array, with each multi-electrode having multiple electrodes at each hole, wherein the multiple embedded electrodes can be two, three, four, six, eight, or more. In one example, the active functional layer of the monolithic porous plate is formed as a lens array, with each lens having only one annular embedded electrode at each hole. Each embedded electrode can be individually connected to a control unit or monitoring unit via external electrical contacts and in a manner electrically insulated from other electrodes or other conductive structures.

[0012] The monolithic porous plate further includes an absorption layer located on the top side or the side where the particle beam is incident. The material forming the absorption layer may include gold, aluminum, or tungsten. The absorption layer of the monolithic porous plate can be designed to be relatively thick, thereby more effectively absorbing or blocking incident particles and X-ray beams.

[0013] In one example, the monolithic perforated plate further includes a central region with a plurality of holes disposed therein; and a peripheral region having a plurality of electrical contact points located on a first side or top side and electrically connected to the connection layer via a through-connection area. For this purpose, the through-connection area includes a plurality of interconnecting channels or vias (VIAs) that are insulated from each other. This allows the lower functional layer to be directly electrically connected to the top side of the monolithic perforated plate via the through-connection area. Alternatively or additionally, the electrical contact points electrically connected to the connection layer via the through-connection area may also be located on the lower side, rather than on the top side.

[0014] In the central region, the thickness T between the first or top side and the second or bottom side of the monolithic porous plate is not less than 100 μm, for example, greater than 150 μm, and preferably not less than 200 μm. In one example, the monolithic porous plate further includes a support layer S4, which contains mechanical contact points or flanges for connecting the multi-beam particle system in the peripheral region.

[0015] The embedded electrode of this monolithic porous plate is formed of a first conductive material and, in each case, is electrically insulated from a further conductive structure made of the first conductive material by an insulating structure made of a second insulating material. In this case, the structure insulating the electrode has at least one exposed area containing the inside of the aperture. In one example, at least one exposed area of ​​the insulating structure is disposed in a recess, the distance R3 from the beam axis of the individual transmitted beam being greater than the inner diameter R1 of the electrode in the aperture. In one example, the electrode includes a tongue or a key, whereby the recess has a labyrinthine form. In one example, the conductive structure includes a tongue or a key, or, along the beam direction, before or above the electrode, the tongue or key covers at least one exposed area. By monolithically integrating the recess and by using the tongue, key, or groove, the exposed area of ​​the insulating structure inside the aperture is protected from the emitted particle beam, thus preventing the accumulation of local charge there.

[0016] In one example, the inner region of the electrode or conductive material on the inside of the hole is additionally coated with metal.

[0017] A second embodiment of the present invention details a method for producing a monolithic porous plate. The method includes the following steps:

[0018] - Step V1: First, a silicon dioxide layer is patterned and polished using photolithography;

[0019] - Step V2, deposit a doped polysilicon layer;

[0020] - Step V3, for chemical mechanical polishing (CMP) depositing a polycrystalline silicon layer;

[0021] - Step V4, followed by photolithographic patterning and polishing of the polycrystalline silicon layer;

[0022] - Step V5, pattern the layer by etching;

[0023] - Step V6, coating the surface with silica;

[0024] - Step V7, chemically and mechanically polish the silica surface formed in step V6; and

[0025] - Step V9, etch holes to allow passage through the monolithic porous plate.

[0026] In one instance, the method additionally includes step V8 of coating a first side or top side of the monolithic porous plate with the absorbent layer.

[0027] In step V9, a thin metal layer may still be selectively applied to the inner surface of the hole.

[0028] The third embodiment details a multi-beam electron beam system having a monolithic porous plate. In one example, the multi-beam electron beam system further includes a first filter plate disposed in the beam path of the electron beam between the particle source and the monolithic porous plate. This pre-filters the incident electron beam and reduces the number of incident or absorbed electrons.

[0029] Provided that no technical contradictions arise, all or part of the various embodiments and aspects of the present invention may be combined with each other. Attached Figure Description

[0030] The invention will be better understood with reference to the accompanying drawings.

[0031] Figure 1 A multi-beam system with a single porous plate is shown.

[0032] Figure 2 Another embodiment of the multi-beam system is shown.

[0033] Figure 3 The cross-section through a single porous plate is shown.

[0034] Figure 4 The structure of a single porous plate is shown.

[0035] Figures 5a to 5c This shows the detailed aspects of a monolithic perforated plate.

[0036] Figures 6a and 6b show exemplary electrode configurations in a monolithic porous plate.

[0037] Figures 7a to 7h illustrate individual steps in the manufacturing process of a monolithic perforated plate.

[0038] Figure 8 An example showing more details of a monolithic perforated plate.

[0039] Figure 9 An example showing more details of a monolithic perforated plate.

[0040] Figure 10 An example of a monolithic porous plate with three active planes is shown.

[0041] Figure 11 An example of a monolithic perforated plate with a through-connection area is shown.

[0042] Figure 12The method steps in the process of generating a plane of a single porous plate are shown.

[0043] Figure 13 An example showing more details of a monolithic perforated plate. Detailed Implementation

[0044] Figure 1 A multi-beam electron beam system 1 according to one embodiment is schematically illustrated. The multi-beam electron beam system 1 (hereinafter also referred to as multi-beam system 1) includes a beam generating device 300 having a particle source 301 (e.g., an electron source) for generating charged particles. A diverging particle beam 309 is collimated by a series of focusing lenses 303.1 and 303.2 and incident on a monolithic porous plate 306. The multi-beam system 1 according to the first embodiment includes exactly one monolithic porous plate 306. A plurality of individual particle beams 3 or individual electron beams 3 are generated and formed by the monolithic porous plate 306 (also referred to as micro-optical units 306). The midpoints of the plurality of apertures in the individual micro-optical unit 306 are arranged in a grating configuration in a first field, which is imaged onto a further grating configuration formed by beam spots 5 in an object plane 101. The distance between the midpoints of the beam spots 5 in the object plane 101 can be, for example, 5 μm, 10 μm, or 100 μm. For example, the spacing between holes in a single porous plate 306 is 100 μm. The diameter D of the holes is smaller than the spacing between the midpoints of the holes; examples of the diameter are 0.2 times, 0.4 times, and 0.8 times the spacing between the midpoints of the holes.

[0045] The individual micro-optical unit 306 and field lenses 307 and 308 are configured in a grating arrangement on the intermediate image surface 321 to generate multiple focal points 323 of the primary beam 3. The intermediate image surface 321 need not be a planar surface, but can be a spherically curved surface to take into account the field curvature of the subsequent particle optics system.

[0046] The multi-beam electron beam system 1 further includes a system of electromagnetic lenses 103 and objectives 102, which images the beam focal point 323 from the intermediate image surface 321 onto the object plane 101 in a reduced size. Meanwhile, the first separate particle beam 3 passes through the beam splitter 400 and the first beam deflector or scanner 110, by which multiple first separate particle beams 3 are deflected and scanned during operation. For example, the first separate particle beams 3 incident on the object plane 101 form a substantially regular field. For example, the field formed by the incident position 5 may have rectangular or hexagonal symmetry.

[0047] The object 7 to be examined can be of any desired type, such as a semiconductor wafer or a biological sample, and may include configurations such as miniaturized components. The surface 25 of the object 7 is disposed in the object plane 101 of the objective lens 102. The objective lens 102 may include one or more electro-optical lenses. For example, this may be a magnetic objective and / or an electrostatic objective. The object 7 (e.g., a wafer) is positioned on a displacement device or platform 500, with the surface 25 located in the image plane 101. The surface 25 is preferably aligned perpendicularly or slightly obliquely to the optical axis 105 of the objective lens 102, and a plurality of first separate particle beams 3 are incident on the object in a manner substantially perpendicular to the object surface 25 and therefore parallel to the optical axis 105. A voltage is supplied to the object 7 on the wafer platform 500 via a voltage supply 503.

[0048] The primary particles of the first separate particle beam 3 incident on object 7 produce interaction products, such as secondary electrons, backscattered electrons, or primary particles that have undergone reverse motion for other reasons, and these interaction products are emitted from surface 25 of object 7 or from a first plane or object plane 101. The interaction products emitted from surface 25 of object 7 are shaped by objective lens 102 to form a secondary particle beam 9. In this process, the secondary particle beam 9 passes through a beam splitter 400 downstream of objective lens 102 and is guided to projection system 200. Projection system 200 includes an imaging system having a plurality of electrostatic or magnetic lenses 206-210, a contrast stop 214, and a multi-particle detector 207. The second separate particle beam 9 is located at a regular interval 15 at the incident position 15 on the detection area of ​​multi-particle detector 207 in a third field. Exemplary values ​​are 10 μm, 100 μm, and 200 μm. In addition, the projection system includes a second beam deflector or scanner 222 for maintaining the incident position 15 of the second separate particle beam 9 on multi-particle detector 207 at a constant position.

[0049] The multi-beam electron beam system 1 further includes a computer system or control unit 800, which may have a single-part or multi-part design, and is designed to control the individual particle optical components of the multi-beam electron beam system 1, and to evaluate and analyze the signals obtained by the multi-detector 207 or detection unit.

[0050] Further information regarding such multi-beam particle or multi-beam electron systems 1 and the components used therein (such as, for example, particle sources, perforated plates, and lenses) is available from international patent applications WO 2005 / 024881 A2, WO 2007 / 028595 A2, WO 2007 / 028596 A1, WO 2011 / 124352 A1 and WO 2007 / 0600172 and German applications DE10 2013 016 113 A1 and DE 10 2013 014 976 A1, the disclosures of which are incorporated herein by reference in their entirety.

[0051] More stringent requirements are imposed on the multi-beam electron beam system 1, particularly for wafer inspection. For example, the resolution of each portion of the image captured using each individual particle beam should be identical within strict tolerances, such as better than 3.5 nm, better than 3.0 nm, or even better. For example, the resolution should be direction-independent; that is, for example, the deviation between the resolution in the x-direction and the resolution in the y-direction should not exceed 5%. The so-called HV difference is also referred to herein. Furthermore, the position of the individual beam spots 5 should be very stable, such that the relative positions of the individual portion images remain stable and corrections are not required through complex calculations to correct for the offsets of many portion images. These stringent requirements first increase the design requirements of the micro-optical unit 306, and secondly, increase the requirements during the operation of the micro-optical unit 306. The multi-beam electron beam system 1 according to an embodiment of the present invention is designed to meet these increased requirements even during operation. To meet the more stringent requirements, the micro-optical unit 306 according to this embodiment has a monolithic design.

[0052] Figure 2 An alternative design of the beam generating apparatus 300 according to an embodiment is shown. A first aperture 311 and a first porous plate or first filter plate 304 having a plurality of first holes are disposed downstream of the electron source 301. The incident electron beam 309 is partially absorbed at the first filter plate 304. Behind the first filter plate 304 are a collimating lens or condenser lens 303 and a monolithic porous plate 306. Behind the monolithic porous plate 306 are a field lens 308 and other components of the multi-beam electron beam system 1, for which please refer to... Figure 1 And related descriptions. Multiple primary beams are deflected by beam splitter 400 through deflection angle 109 to the optical axis 105 of objective lens 102. Deflection angle 109 may be between 3° and 20°, preferably between 4° and 10°. However, smaller or larger deflection angles 109 are also possible.

[0053] The first filter plate 304 is sometimes also referred to as the pre-perforated plate 304. The first filter plate 304 can be used to reduce the load on the individual micro-optical unit 306 caused by the incident electron flow from the electron beam 309.

[0054] Especially for wafer inspection, the requirements for isotropic resolution and uniformity of imaging resolution of multiple particle beams are becoming increasingly stringent. Isotropic resolution means that the deviation of the resolution in the x-direction from the resolution in the y-direction perpendicular to it does not exceed, for example, 5%. Preferably, the deviation is even smaller, for example, 3% or even less. Additionally, the resolution of the first beam should deviate from the resolution of the second beam by no more than 5%, preferably less than 3%. This isotropic and invariant resolution is achieved when the beam profile 115 in the pupil plane 117 is circular and all beams have the same diameter. Therefore, the (real or virtual) beam profile 119 of all the first beams 3 is identical and circular in the plane 111 parallel to the image plane.

[0055] Figure 3 A cross-section of the exemplary monolithic micro-optical unit 306 is explained in detail. For simplicity, only four holes 85 are shown for forming four individual beams 3.1 to 3.4. However, a greater number of holes is possible, such as 50, 100, 300, or even more, for example, about 1000, depending on the number of individual particle beams 3 to be generated. The spacing P1 between the holes is approximately 100 μm or greater. For example, the holes 85 can be configured as Cartesian gratings or hexagonal configurations. Other configurations are also possible. The holes 85 extend between a first side or top side 313 and a second side or bottom side 315 of the monolithic porous plate 306. The diameter of each hole is approximately 50 μm. In the central region 191 containing the holes 85, the thickness T of the monolithic porous plate 306 is greater than 100 μm, for example 150 μm or 200 μm or greater, for example 300 μm. Specifically, the monolithic porous plate 306 does not contain any thin films with a thickness less than 50 μm, as is common in the prior art. Therefore, individual films do not undergo any deformation. Furthermore, the individual micro-optical unit 306 does not have a stacked structure and does not form a stack of individual components. This allows for management without adjusting and connecting individual components, as adjusting and connecting individual components is prone to errors.

[0056] Electron beam 309 is emitted from electron source 301 and filtered at first filter plate 304 (not shown). A monolithic porous plate 306 includes a first functional layer S1 having a plurality of holes 85. This shapes the profiles of individual beams 3.1 to 3.4. In this case, each beam profile of individual beam 3.1 corresponds to the hole shape of the hole 85 in the first functional layer S1. In this case, the hole shape of the first beam-forming holes 85 in the functional layer S1 can be designed to be individually different, and for example, have different elliptical designs. For example, the first functional layer S1 includes an absorption layer 99 formed of a conductive material preferably having a high density or high atomic number (e.g., aluminum, gold, lead, or tungsten). The absorption layer 99 of the monolithic porous plate 306 can be designed to be very thick, for example, up to 5 μm or more. Therefore, excess electrons of the pre-filtered individual beam 3 that have not passed through the holes 85 are captured and absorbed. The absorption layer 99 is connected to a large capacitor, for example, ground (or a 0V reference potential). The thick absorption layer 99 is also suitable for blocking X-ray radiation.

[0057] Apart from the absorption layer 99 on the top side 313, the monolithic porous plate 306 is essentially composed of a first conductive material (e.g., doped silicon or polycrystalline silicon) and a second non-conductive material (e.g., silicon dioxide). Except for the holes 85, the monolithic porous plate 306 has no gaps or cavities.

[0058] Then, individual beams 3.i pass through the additional functional layers S2, S3, and S4 of the monolithic porous plate 306. In this example, the functional layers in the monolithic porous plate 306 have a dual sequence of passive functional layers S2.1 and S2.2 and active functional layers S3.1 and S3.2 having electrodes 81.1 and 81.2. Finally, there is also an additional passive functional layer S2.3 and a support layer S4, which can also be provided as integral components of the monolithic porous plate 306. For example, the support layer S4 includes a mechanical flange or support frame 86. For example, the monolithic porous plate 306 together with the support frame 86 has a thickness of approximately 0.5 mm to 1 mm.

[0059] During operation, an electric field is generated by applying a voltage at embedded electrodes 81.1 and 81.2 to produce an individual beamforming or deflection effect on each individual beam 3.i. For example, a single individual beam 3 may have different focusing, different deflection, or other different effects depending on its beam shape. For this purpose, embedded electrodes 81.1 and 81.2 are respectively connected to control unit 830 (see...). Figure 2 ).

[0060] Figure 4A simplified example of a cross-section of a monolithic porous plate 306 is shown. The monolithic porous plate 306 is predominantly (i.e., greater than 50%, greater than 70%, or even greater than 80%) formed of a conductive material 87 (e.g., doped silicon). Within this conductive material 87, individual conductive structures 93 are surrounded by and thus electrically insulated from each other by an insulating material 89. For example, the insulating material 89 may be provided as silicon dioxide. The individual conductive structures 93 are embedded in and surrounded by the insulating material and may also be defined by a region of at least one inner wall of a hole 85. Thus, electrically insulated individual conductive structures 93 are formed within the conductive material 87, for example, structures consisting of electrodes 81 and electrical connection channels or lines 75. A plurality of electrical connection channels 75 and 77 connect each electrode 81 to a corresponding connection contact 83, which is provided, for example, in a first functional layer S1 on the top side 313 of the monolithic porous plate 306 for electrical connection to a control unit 830. A voltage difference is applied between electrode 81.1 and another electrode on the same aperture opening 85.1 to obtain beam deflection or astigmatism correction of individual beams 3. The voltage difference can be applied to electrode 81.1 or another electrode 81.2 in another functional layer to, for example, obtain a focusing effect of individual beams 3.

[0061] For example, a portion of the conductive structure 93.1 is formed by a vertical connecting channel 75.1, which may have a diameter of approximately 5 μm. Another portion of the conductive structure 93.1 is formed by an electrode 81.1, which may have a thickness of up to approximately 50 μm. Yet another portion of the conductive structure 93.1 is formed by a horizontal connecting channel 77.1 between the electrode 81.1 and the vertical connecting channel 75.1. The diameters of the horizontal connecting channels 77.1 and 77.2 may range from 0.25 μm to 5 μm. The thickness of the insulating material 89 between the two conductive structures 93.1, 93.2, or 93.3 is at least 0.5 μm; however, a thickness of up to 5 µm is also possible.

[0062] The diameters of the holes 85 in the individual functional layers S1 to S3 can be different. The diameter D1 in the uppermost functional layer S1 is smaller than the diameter D2 in the active functional layer S3. In contrast, the diameter D3 in the passive functional layer S2 can be designed to be larger than the diameter D2. This prevents electrons from the individual electron beams 3 from contacting the inner diameter wall of the holes 85 below the first functional layer S1.

[0063] In this case, functional layers S1, S2 and S3 contain multiple planes or thin layers, as shown in the example of using functional layer S3.1 with planes or thin layers L1 to L5. Figure 5aAn embodiment of the design of the active functional layer S3.i with electrode 81 is shown. The first and third thin layers L3 contain portions of insulating structures 89 or 91. The second thin layer L2 contains portions of electrical connection lines 77.1. The fourth thin layer L4 contains, in particular, portions of conductive structure 93.3 and embedded electrode 81. The fifth thin layer L7 contains portions of insulating structure 91. Insulating structures 91 and 89 electrically insulate the embedded electrode 81 from the conductive structure 93.3 in thin layer L4 and the conductive structures located above and below it. Conductive structure 93.3 is not completely insulated and is connected, for example, to a 0V reference potential via connection 95. Conductive structure 93.3 shields the electric field and thus acts as a shield between the embedded electrode 81 and other embedded electrodes (not shown here). Conductive connections 75.1 and 75.2 are formed as cylindrical insulated conductive channels and are shown in cross-section here in each case.

[0064] An insulating structure 89 or 91 with an exposed region 73 of the aperture 85 is configured to insulate the embedded electrode 81 from the electrical connection lines 75.1 and 77.1. Scattered electrons can adhere to the exposed insulating region 73 of the insulating structure 89 during operation and can cause local space charge there. To prevent the adhesion of scattered electrons or the generation of local space charge, the exposed region 73 is disposed in a recess 71 at a distance R3 from the beam axis 121 of the individual primary beam 3, wherein R3 is selected to be greater than the radii R0 and R5 of the functional layer S2 disposed above or below it, respectively, and in particular, also greater than the radius R1 of the inner wall of the electrode 81. Thus, a direct “line of sight” between the exposed region 73 and the individual beam 3 is avoided. The recess 71.1 has a width B in the propagation direction of the electron beam 3, which is determined by… Figure 5a The z-axis provides the width B. Figure 5a The thickness of the first thin layer L1. In one example, the width B is selected to be less than the difference between the radius R3 of the recess 71.1 and the radius R1 of the electrode 81, such that B < (R3-R1) applies.

[0065] Figure 5bAnother embodiment of the design of the active functional layer S3.i with electrode 81 is shown. In this example, the active functional layer S3.i is composed of nine individual planar or thin layers L1 to L9. The third planar or thin layer L3 contains a portion of the insulating structure 89. The fourth thin layer L4 contains an electrical connection line 75.1. The fifth thin layer L5 contains a portion of the insulating structure 91. The sixth thin layer L6 contains, in particular, a conductive structure 93 and a portion of the embedded electrode 81. The seventh thin layer L7 contains a portion of the insulating structure 91. The insulating structures 91 and 89 electrically insulate the electrode 81 from the conductive structure 93 in thin layer L6 and the conductive structures located above and below it. To prevent scattered electrons from adhering or forming local charges on the exposed area 73, the electrode 81 in thin layer L2 extends above the insulating structure and forms a curved gap 79.1 relative to the exposed area 73 in thin layers L1 and L2. The curved gap or recess 79.1 is further enlarged by a protrusion or embedding portion 61 formed on the electrode 81. Therefore, there is no direct line of sight between the exposed area 73 and the electron beam 3, reducing the probability of scattered electrons reaching the exposed area 73. An additional tortuous vacuum gap 79.2 can be provided below the electrodes 81 in the thin layers L8 and L9 (as seen in the beam direction).

[0066] exist Figure 5b In this example, the inner surface of the aperture 85 further comprises a thin metal layer 67. The metal layer 67 can be introduced into the aperture 85 with a thickness of several nanometers (e.g., 5 nanometers). This metal layer serves as a protective layer and prevents adhesion or formation of localized charges on the conductive structure 93 or electrode 81. Applying only the thin layer 67 prevents the formation of metal layers in the recesses 71 and 79 as well. The metal layer can be formed of copper, aluminum, gold, or tungsten.

[0067] Figure 5c Another embodiment of the design of the active functional layer S3.i with electrode 81 is shown. To prevent the adhesion of scattered electrons or the formation of local charges on the exposed region 73, the conductive structure in the functional layer S2.i extends above the exposed region 73.1 via a tongue or key 65.1. A similar tongue or key 65.2 is provided below the key electrode 81, i.e., in the top-to-bottom bundle direction.

[0068] Electrode configuration 81 may be formed of annular electrodes to create an enezel lens. However, electrode configuration 81 may also be formed as a multi-electrode configuration 81, for example, having eight electrodes (81.1 to 81.8) surrounded by an insulating structure 91. Figure 6 shows an example of electrode configuration 81 with eight embedded electrodes 81.1 to 81.8 surrounding a hole 85. Individual exposed areas 73 of the insulating structure 91 are located between two correspondingly separate embedded electrodes. To prevent scattered electrons from reaching the exposed areas 73, the electrodes are formed with grooves 63 and corresponding embedded portions or protrusions 61, 65, such that the embedded portion 61 of one electrode 81.1 protrudes into the groove of the adjacent electrode 81.2, and together with the embedded portion 65 of the adjacent electrode 81.2, forms a tortuous vacuum gap 79 (see Figure 6b). The vacuum gap 79 further shields the disturbance field generated from the structure located behind it. Furthermore, a metal layer 67 may be present on the inner side of electrodes 81.1 to 81.8.

[0069] Figure 7 illustrates an example of several individual intermediate steps in the fabrication process of the monolithic porous plate 306. In the first step, the bottom silicon-doped plate 171.9 has an insulating silicon dioxide layer 169.9 (Figure 7a). The silicon dioxide layer is patterned by photolithography, and an additional silicon-doped layer 171.8 is epitaxially grown or patterned in a plasma reactor (e.g., PECVD / plasma-enhanced chemical vapor deposition). For this purpose, photolithographic patterning includes photolithographic exposure and at least one etching. An additional insulating silicon dioxide layer 169.8 (Figure 7b) is formed on top of it. These steps are repeated (Figures 7c to 7d), and additional layers 171.8 to 171.1 are formed (only layers up to 171.6 are shown for simplicity). In each layer, conductive structures are photolithographically separated by insulating structures; for example, these subsequently form embedded electrodes 81 and conductive connections 75. Therefore, different functional layers of a monolithic porous plate 306 are formed, wherein the first functional layer 177 has a supporting function, the second functional layer 175 forms a passive electrode or spacer, and the third functional layer 181 has an active electrode 81. Finally, a conductive absorption layer 99 made of a dense material is applied and patterned (Fig. 7e). In order to perform chemical through-etching on the subsequent holes 85, an etch protection layer 173 is applied and photolithographically patterned according to the subsequent holes 85 (Fig. 7e). Subsequently, the holes 85 are etched into doped silicon, wherein the etch protection layer 173 and the structure made of silicon dioxide act as the etch protection layer 173 (Fig. 7f). Fig. 7g shows the result of through-etching the holes, for example, after wet chemical removal of the exposed silicon dioxide layer. In the holes 85, thin metal layers 67.1 and 67.2 are applied to the internal regions by deposition. Finally, the etch protection layer 173 is removed (Fig. 7h). Figure 8 Finally, the uppermost thin layer of the monolithic porous plate 306 facing the incident electron beam 309 is shown. For reference numerals and their explanations, refer to the above figures and descriptions, especially... Figure 4 See Figure 6 and its description. The connection contact 83 for the electrical connection electrode 81 is also connected to the control unit 830. Therefore, many emitted electron beams are individually affected during operation (e.g., including at least one of focusing, beam shaping (e.g., astigmatism reshaping or application of a higher multipole field) or beam deflection).

[0070] Figure 9 Another embodiment of a structure for preventing exposed areas of an insulating structure from becoming charged is shown. In this example, the uppermost doped silicon layer 171.1 has inset portions and protrusions 65.1 extending above the insulating layer below it. Therefore, the exposed area 73 below is protected, and the probability of scattered electrons reaching the exposed area 73 is reduced. For reference numerals and their explanations, refer to the above figures and description, particularly... Figure 4 And Figure 5 and its description.

[0071] Figure 13 Another embodiment is shown. Figure 13 In this example, the thickness T1 of the uppermost absorber layer 99 is, for example, 1.5 μm. The absorber layer is, for example, made of gold. The doped silicon layer 171.1 below it has a conical opening, wherein the angle G1 lies between the axial tangent of the conical opening and the perpendicular 317 to the surface 313 of the absorber layer 99. Figure 13 In this context, for example, angle G1 is described as 7°; however, angle G1 can also be very large, and for example equal to 30° or 35°.

[0072] On the upper side facing the absorption layer 99, the diameter of the hole 85 in the first layer 171.1 therefore has a first diameter D3.1 that is smaller than the diameter 3.2 on the far lower side. For example, D1 < D3.1 < D3.2 applies. Exemplary values ​​for the diameter are D1 = 25 μm, D3.1 = 26.5 μm, and D3.2 = 30 μm. Alternative values ​​for the diameter are D1 = 30 µm, D3.1 = 31.5 µm, and D3.2 = 35 µm. Further alternative values ​​for the diameter are D1 = 35 µm, D3.1 = 37 µm, and D3.2 = 40 µm. The net inner diameter D2 of the hole 85 between the electrodes 81 is, for example, selected to be between the diameters D3.1 and D3.2, such that D3.1 < D2 < D3.2 applies.

[0073] Furthermore, due to the etching of the aperture opening 85 through the monolithic porous plate 306, there may be insufficient etching 319 for the absorption layer 99. Following the absorption layer 99 and the selective etching insufficient 319, the conical design of the aperture opening 85 with a diameter D3.1 < D3.2 in the uppermost layer made of doped silicon or polysilicon (171.1) further prevents the adhesion of interfering charged particles inside the aperture opening 85.

[0074] Figure 10 An example of a monolithic porous plate having a total of three active functional layers 181.1 to 181.3 is shown. The active functional layers 181.1 to 181.3 allow for independent and individual focusing, deflection, and beamforming of individual beams 3.1 and 3.2. For this purpose, each of the embedded electrodes 81.1 to 81.6 is implemented as a multi-electrode electrode. Additionally, a thin metal layer may be applied to the internal region of the aperture 85 (not shown here). For example, field curvature and image plane tilt of the subsequent electro-optics system can be compensated by active focusing elements. For example, aberrations of the subsequent electro-optics system can be compensated by active beamforming elements. For example, the beam spacing can be set, or distortions of the subsequent electro-optics system can be compensated by active beam deflection elements. Except for the individually designed electrical connection channels 75.1 to 75.6, the planes with the same function are largely identical, and the mask used for photolithographic patterning can be reused multiple times. The monolithic porous plate 306 does not contain cavities except for the multiple apertures 85. Therefore, the monolithic porous plate 306 is less sensitive to thermal deformation. For other reference numerals and their explanations, please refer to the foregoing diagrams and descriptions, especially... Figure 4 And Figure 5 and its description, and Figure 11 And its description.

[0075] Figure 11 A schematic overview of a cross-section of a monolithic porous plate 306 having three active functional layers 181.1 to 181.3 and insert connection layers 183.1 to 183.6 containing electrical connection channels 75 for electrical contact of electrodes 81 is shown. The monolithic porous plate 306 further includes at least one purely passive functional layer 175.1 to 175.3, which is essentially used to establish a free propagation spacing for emitted electron beams 3.1 to 3.5. The monolithic porous plate 306 includes a central region 191 with a plurality of holes 85, only five of which are shown. Furthermore, a peripheral region 193 of the monolithic porous plate 306 includes through connection areas 195 for electrically connecting individual connection layers 183.1 to 183.6 to electrical contacts 83 disposed on a top side 313. The monolithic porous plate 306 is connected to a control unit 830 via the electrical contacts 83.

[0076] The monolithic porous plate 306 comprises repeating sequences of functional layers 189.1 to 189.3, each consisting of at least one active functional layer 181 with embedded electrodes 81, a connecting layer 183, and a passive functional layer 175. For reference numerals and their explanations, please refer to the foregoing figures and descriptions. Except for the holes 85, the monolithic porous plate 306 has no gaps or cavities compared to the prior art, as contaminants can accumulate and make vacuum operation more difficult. Furthermore, unlike the prior art, the monolithic porous plate is not constructed by stacking individual porous plates, thus eliminating the need for error-prone adjustments and connections. Therefore, more functional layers can be integrated, such as three or more functional layers. This also allows the lower functional layers to be directly electrically connected to the top side 313 of the monolithic porous plate 306 via a through-connection area 195, compared to the prior art. The recesses 71 and 79 integrated by the single unit and the protrusions, inserts or grooves 61, 63, and 65 can also protect the exposed area 73 of the insulating structure inside the hole from the influence of the transmitted particle beam 3, that is, the particle beam 3 passes through the single porous plate, so that local charge cannot accumulate there.

[0077] Figure 12 The iterative steps of an additional fabrication method for individual layers of a monolithic porous plate 306 are illustrated schematically. In step V1, a polished silicon dioxide layer is first patterned using photolithography. In step V2, doped polysilicon is deposited. In step V3, the deposited polysilicon is chemically mechanically polished (CMP). In step V4, the pattern is again patterned using photolithography. In step V5, the layer is etched to pattern it. In step V6, the surface of the etched structure is provided or filled with silicon dioxide. Subsequently, in step V7, the silicon dioxide surface is polished using CMP. The method steps are repeated until the monolithic porous plate 306 is completely constructed (step Q). Then, in step V8, an absorber layer 99 is coated, and in step V9, holes are etched and a thin metal layer 67 is introduced into the holes 85.

[0078] The following list of figure labels is provided.

[0079] 1. Multi-beam electron beam system

[0080] 3 Individual particle beams

[0081] 5-spot cluster

[0082] 7. Objects or chips

[0083] 9 Secondary particle beams

[0084] 15. Incident position of individual secondary particle beams

[0085] 25. The surface of an object

[0086] 61 convex part / embedded part

[0087] 63 slots

[0088] 65 convex part / embedded part

[0089] 67 Thin metal layer

[0090] 71 recess

[0091] 73 Exposed Areas

[0092] 75 Electrical connection channel

[0093] 77 Electrical connection channel

[0094] 79 Labyrinth recess

[0095] 81 One or more electrodes

[0096] 83 Electrical contact points

[0097] 85 One or more holes

[0098] 86 Mechanical flange

[0099] 87 Conductive Materials

[0100] 89 Insulation Materials

[0101] 91 Insulation Structure

[0102] 93 Conductive Structure

[0103] 95 Conductive connection

[0104] 99 Absorption Layer

[0105] 101 Object plane

[0106] 102 Objective Lens

[0107] 103 Electromagnetic Lens

[0108] 105 optical axes

[0109] 109 deflection angle

[0110] 110 Focusing Deflector

[0111] 111 A plane parallel to the image plane

[0112] 115 beam profile

[0113] 117 Pupil plane

[0114] 119 The first individual bundle profile

[0115] 121. The bundle axis of individual bundles

[0116] 169 silicon dioxide layer

[0117] 171 Doped Silicon / Polycrystalline Silicon

[0118] 173 Etched Protective Layer

[0119] 175 Passive Functional Layer

[0120] 181 Active Functional Layer

[0121] 183 Connection Layer

[0122] 189-layer sequence

[0123] 191 Central Area

[0124] 193 Outer Area

[0125] 195 Straight-through connection area

[0126] 200 Projection System

[0127] 206 Electrostatic or magnetic lens

[0128] 207 Multiple Particle Detector

[0129] 208 Electrostatic or magnetic lens

[0130] 209 Electrostatic or magnetic lens

[0131] 210 Electrostatic or magnetic lens

[0132] 214 Contrast Aperture

[0133] 218-beam deflector

[0134] 222 Second Focusing Deflector

[0135] 300-beam generation device

[0136] 301 Particle Source

[0137] 303 Collimating Lens

[0138] 304 First Filter Plate

[0139] 306 Single-piece perforated plate

[0140] 307 field lens

[0141] 308 field lens

[0142] 309 Particle Beam

[0143] 311 First Aperture

[0144] 313 First side or top side

[0145] 315 Second side or bottom side

[0146] 317 The perpendicular line from the top side 313

[0147] 319 Insufficient Etching

[0148] 321 Intermediate image surface

[0149] 323 Focus

[0150] 400 beam splitter

[0151] 500 displacement device or platform

[0152] 503 Voltage Supply

[0153] 800 Control Unit

[0154] 830 primary beam control unit

Claims

1. A monolithic porous plate (306) for a multi-beam electron beam system (1), comprising a first conductive material (87) and a second insulating material (89) and having a plurality of holes (85), the plurality of holes forming a continuous connection between a first side or top side (313) and a second side or bottom side (315) of the porous plate (306), wherein at least one first sequence and at least one second sequence (189.1, 189) of functional layers (181, 183, 175) 189.2, 189.3) are formed of the first conductive material and the second insulating material. The first sequence and the second sequence (189.1, 189.2, 189.3) each include an active functional layer (181.1, 181.2, 181.3) having multiple electrodes (81), at least one connection layer (183.1 to 183.6) having multiple electrical connection channels (75, 77) and a passive functional layer (175.1, 175.2, 175.3).

2. The monolithic perforated plate (306) as claimed in claim 1 further comprises a central region (191) and a peripheral region (193), wherein the plurality of holes (85) are disposed in the central region (191), and the peripheral region (193) has a plurality of electrical connection contacts (83) electrically connected to the connection layer (183.1 to 183.6) via a through connection area (195), wherein the through connection area (195) extends through the at least first sequence and second sequence (189.1, 189.2, 189.3) of the functional layer (181, 183, 175).

3. The monolithic porous plate (306) as described in claim 1 or 2, wherein... Electrodes (81, 81.1, 81.2, 81.3, 81.4, 81.5, 81.6, 81.7, 81.8) are formed of the first conductive material (87) and are electrically insulated from another conductive structure made of the first conductive material (87) by an insulating structure (91) made of the second insulating material (89), wherein the insulating structure (91) has at least one exposed area (73) containing the inner side of the hole (85), and wherein the at least one exposed area (73) is disposed in a recess (71, 71.1, 71.2, 79) at a distance R3 from the beam axis (121) of the electron beam (3), the distance R3 being greater than the inner diameter R1 of the hole (81).

4. The monolithic porous plate (306) as claimed in claim 3, wherein the recess (71, 71.1, 71.2, 79) has a width B along the propagation direction of the electron beam (3), wherein B < (R3-R1).

5. The monolithic porous plate (306) as claimed in claim 3 or 4, wherein the electrode (81.1 to 81.8) has a protrusion or an embedded portion (65, 65.1, 65.2), and wherein the recess (79, 79.1, 79.2) is in the form of a curved path.

6. The monolithic porous plate (306) as claimed in any one of claims 1 to 5, wherein the electrodes (81, 81.1, 81.2, 81.3, 81.4, 81.5, 81.6, 81.7, 81.8) are formed of the first conductive material (87) and are electrically insulated from another conductive structure made of the first conductive material (87) by an insulating structure (91) made of the second insulating material (89), wherein the insulating structure (91) has at least one exposed area (73) on the inside containing a hole (85), and wherein the conductive structure above the electrodes (81.1 to 81.8) includes a protrusion or an embedded portion (65, 65.1) that covers the at least one exposed area (73) of the insulating structure (91).

7. The monolithic porous plate (306) as described in any one of claims 1 to 6, further comprising an absorption layer (99) on the top side (313).

8. The monolithic porous plate (306) as claimed in claim 7, wherein the absorbent layer (99) is made of gold, aluminum or tungsten.

9. The monolithic porous plate (306) as claimed in claim 7 or 8, wherein the monolithic porous plate (306) is formed entirely of the materials of the first conductive material (87), the second insulating material (89) and the absorbent layer (99), without having separation points or contained cavities.

10. The monolithic perforated plate (306) according to any one of claims 1 to 9 further comprises a support layer S4 having mechanical contact points or flanges (86).

11. The monolithic porous plate (306) according to any one of claims 1 to 10, wherein the monolithic porous plate (306) has a thickness T greater than 100 µm between the first side or top side (313) and the second side or bottom side (315).

12. The monolithic porous plate (306) according to any one of claims 1 to 11, wherein the monolithic porous plate (306) has a thickness T greater than 150 µm, preferably greater than 200 µm, between the first side or top side (313) and the second side or bottom side (315).

13. A method for generating a monolithic porous plate (306) as described in any one of claims 1 to 12, the method comprising at least two repeated sequences of the following steps: - Step V1: First, a silicon dioxide layer is patterned and polished using photolithography; - Step V2, deposit a doped polysilicon layer; - Step V3, for chemical mechanical polishing (CMP) deposition of the doped polysilicon layer; - Step V4, the doped polysilicon layer is then patterned and polished by photolithography; - Step V5, pattern the layer by etching; - Step V6, coating the surface with silica; and - Step V7, chemical mechanical polishing (CMP) of the silica surface formed in step V6.

14. A method for producing a monolithic porous plate (306) as claimed in claim 13, the method further comprising step V9 of etching the holes (85) into the monolithic porous plate (306).

15. A method for generating a monolithic porous plate (306) as claimed in claim 13 or 14, the method further comprising step V8, to coat the first side or top side (313) of the monolithic porous plate (306) with the absorbent layer.

16. A multi-beam electron beam system having a monolithic porous plate (306) as described in any one of claims 1 to 12.

17. The multi-beam electron beam system (1) as claimed in claim 16 further includes a first filter plate (304) disposed in the beam path of the electron beam (309) between the particle source (301) and the monolithic porous plate (306).

18. The multi-beam electron beam system (1) as claimed in claim 16 or 17, wherein at least one active functional layer (183.1, 183.2, 183.3) of the monolithic porous plate (306) is formed as a multipole element having a plurality of electrodes (81.1 to 81.8) at each hole (85).

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