Electron beam apparatus, inspection tool, and inspection method

Abstract

An electron beam apparatus is described, the apparatus comprising: an electron beam source configured to generate an electron beam; a beam conversion unit including: an aperture array configured to generate a plurality of beamlets from the electron beam; a deflector unit configured to deflect one or more groups of the plurality of beamlets; and a projection system configured to project the plurality of beamlets onto an object. The deflector unit is configured to deflect the one or more sets of the plurality of beamlets to illuminate the object at different angles of incidence, each beamlet in a set having substantially the same angle of incidence on the object.

Description

[0001] Cross-reference to related applications

[0002] This application claims the priority of European Application No. 18174621.5 filed on May 28, 2018, the entire content of which is incorporated herein by reference. Technical field

[0003] The present invention relates to an electron beam device, an inspection tool, an inspection method, and an exposure device. Background art

[0004] A lithographic apparatus is a machine that applies a desired pattern onto a substrate (typically onto a target portion of the substrate). A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, alternatively referred to as a mask or a reticle, can be used to generate a circuit pattern to be formed on a single layer of the IC. Such a pattern can be transferred onto a target portion (e.g., a portion including dies, a single die, or several dies) on the substrate (e.g., a silicon wafer). Typically, the transfer of the pattern is effected via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. Usually, a single substrate will include a network of adjacent target portions that are successively patterned. Conventional lithographic apparatuses include: so-called steppers, in which each target portion is irradiated by exposing the entire pattern onto the target portion at once; and so-called scanners, in which each target portion is irradiated by scanning the pattern with a radiation beam in a given direction ("scanning" direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. The pattern can also be transferred from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0005] As a radiation beam typically applied to a lithographic apparatus can be, for example, a DUV radiation beam (e.g., having a wavelength of 248 nm or 193 nm) or an EUV radiation beam (e.g., having a wavelength of 11 nm or 13.5 nm).

[0006] Patterning of a substrate can also be achieved using an electron beam or a plurality of electron beams. Such a technique is generally referred to as electron beam lithography.

[0007] The manufacture of an integrated circuit typically may require a stack of multiple layers, thus requiring accurate alignment of the layers. In the absence of such alignment, the required connections between the layers may be defective, leading to failures of the integrated circuit.

[0008] Typically, the bottom layer or multiple bottom layers of an integrated circuit will contain the smallest structures, such as transistors or their components. The structures of subsequent layers are typically larger and allow the connection of the structures in the bottom layer to the outside world. In view of this, the alignment of two layers will be most challenging in the bottom portion of the integrated circuit.

[0009] To ensure proper patterning of a circuit or a circuit layer, a substrate is typically subjected to inspection using an inspection tool such as an electron beam inspection tool. Such a tool can be applied, for example, to evaluate whether certain process steps, such as those performed by a lithographic apparatus, have been carried out as intended.

[0010] There is a desire to improve the performance of electron beam lithographic apparatuses and electron beam inspection tools, such as those currently available. SUMMARY OF THE INVENTION

[0011] There is a desire to improve the performance of an electron beam inspection tool or an exposure apparatus. To solve these problems, according to an aspect of the present invention, there is provided an electron beam apparatus including:

[0012] - an electron beam source configured to generate an electron beam;

[0013] - a beam conversion unit including:

[0014] - a hole array configured to generate a plurality of sub-beams from the electron beam;

[0015] - a deflector unit configured to deflect one or more of the plurality of sub-beams;

[0016] - a projection system configured to project the plurality of sub-beams onto an object,

[0017] wherein the deflector unit is configured to deflect one or more of the plurality of sub-beams so as to irradiate the object at different incident angles.

[0018] According to another aspect of the present invention, there is provided a method of inspecting an object, the method including:

[0019] - generating a plurality of sub-beams from an electron beam source, the sub-beams being configured to irradiate the object at different incident angles;

[0020] - detecting a response signal from the object in response to irradiating the object with the plurality of sub-beams;

[0021] - processing the response signal to determine a characteristic of the object. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the present invention will now be described, by way of example only, with reference to the schematic drawings in which corresponding reference numerals indicate corresponding parts and in which:

[0023] Figure 1A a lithographic apparatus according to an embodiment of the present invention is depicted;

[0024] Figure 1BDepict an electron beam device according to an embodiment of the present invention;

[0025] Figure 2A Depict an inspection tool known in the art;

[0026] Figure 2B Depict an inspection tool according to an embodiment of the present invention.

[0027] Figure 3a And Figure 3b Schematically depict a top view and a side view of an inspection tool according to the present invention;

[0028] Figures 4A to 6B Illustrate the use of the present invention for inspecting an object such as a semiconductor substrate;

[0029] Figures 7A to 7C Illustrate a first embodiment of a beam conversion unit that can be applied to an electron beam device according to the present invention;

[0030] Figure 8 Depict a second embodiment of a beam conversion unit that can be applied to the present invention;

[0031] Figure 9 Depict generating multiple sub - beams using an electron beam device according to the present invention;

[0032] Figure 10 Depict a sub - beam blanking array that can be applied to an exposure device according to the present invention.

[0033] Figure 11 Schematically depict an inspection tool known in the art. Detailed Description

[0034] FIG. 1 schematically depicts a lithographic apparatus according to an embodiment of the present invention. The apparatus includes: an illumination system (illuminator) IL, which is configured to condition a radiation beam B (e.g., UV radiation or any other suitable radiation, such as electron beam radiation or EUV radiation); a mask support structure (e.g., a mask table) MT, which is configured to support a patterning device (e.g., a mask) MA and is connected to a first positioning device PM configured to accurately position the patterning device according to certain parameters. The apparatus also includes a substrate table (e.g., a wafer table) WT or “substrate support”, which is configured to hold a substrate (e.g., a wafer coated with resist) W and is connected to a second positioning device PW configured to accurately position the substrate according to certain parameters. The apparatus further includes a projection system (e.g., a refractive projection lens system) PS, which is configured to project the pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., including one or more dies) of the substrate W.

[0035] The illumination system may include various types of optical components for directing, shaping or controlling radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof.

[0036] The mask support structure supports the patterning device (i.e., bears the weight of the patterning device). The mask support structure holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus and other conditions, such as whether the patterning device is held in a vacuum environment. The mask support structure may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device. The mask support structure may be, for example, a frame or a table that can be fixed or movable as required. The mask support structure may ensure that the patterning device is, for example, in a desired position relative to the projection system. Any use of the term "reticle" or "mask" in this document may be considered synonymous with the more general term "patterning device".

[0037] The term "patterning device" as used in this document should be interpreted broadly as referring to any device that can be used to impart a pattern in a cross-section of a radiation beam so as to create a pattern in a target portion of a substrate. It should be noted that, for example, if the pattern imparted to the radiation beam includes phase-shifting features or so-called assist features, the pattern may not exactly correspond to the desired pattern in the target portion of the substrate. In general, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device (such as an integrated circuit) created in the target portion.

[0038] The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays and programmable LCD panels. Masks are well known in lithography and include mask types such as binary, alternating phase-shift and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect an incident radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam reflected by the mirror matrix.

[0039] The term "projection system" as used in this document should be interpreted broadly as encompassing any type of projection system suitable for the exposure radiation used or for other factors such as the use of an immersion liquid or the use of a vacuum, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof. Any use of the term "projection lens" in this document may be considered synonymous with the more general term "projection system".

[0040] As depicted herein, the device is of the transmissive type (e.g., using a transmissive mask). Alternatively, the device may be of the reflective type (e.g., using a programmable mirror array of the type mentioned above, or using a reflective mask).

[0041] The lithographic apparatus may be of the type having two (dual stage) or more than two substrate tables or "substrate supports" (and / or two or more than two mask tables or "mask supports"). In such a "multi-stage" machine, additional tables or supports may be used in parallel, or preparatory steps may be carried out on one or more tables or supports while one or more other tables or supports are used for exposure.

[0042] The lithographic apparatus may also be of the type in which at least a portion of the substrate may be covered by a liquid having a relatively high refractive index (e.g., water) in order to fill the space between the projection system and the substrate. The immersion liquid may also be applied to other spaces in the lithographic apparatus, e.g., the space between the mask and the projection system. Immersion techniques can be used to increase the numerical aperture of the projection system. The term "immersion" as used herein does not mean that a structure such as a substrate must be immersed in a liquid, but only that the liquid is located between the projection system and the substrate during exposure.

[0043] Referring to FIG. 1, the illuminator IL receives a radiation beam from a radiation source SO. When the source is, for example, an excimer laser, the source and the lithographic apparatus may be separate entities. In such cases, the source is not considered to be part of the lithographic apparatus, and the radiation beam is transmitted from the source SO to the illuminator IL by means of a beam delivery system BD including, for example, suitable directing mirrors and / or beam expanders. In other cases, such as when the source is a mercury lamp, the source may be an integral part of the lithographic apparatus. The source SO, the illuminator IL, together with the beam delivery system BD (if required), may be referred to as the radiation system.

[0044] The illuminator IL may include an adjuster AD configured to adjust the angular intensity distribution of the radiation beam. In general, at least the outer radial extent and / or the inner radial extent of the intensity distribution in the pupil plane of the illuminator can be adjusted (commonly referred to as σ-outer and σ-inner, respectively). Additionally, the illuminator IL may include various other components, such as an integrator IN and a condenser CO. The illuminator can be used to condition the radiation beam to have a desired uniformity and intensity distribution in its cross-section.

[0045] The radiation beam B is incident on a patterning device (e.g., mask MA) held on a mask support structure (e.g., mask table MT) and is patterned by the patterning device. After having traversed the mask MA, the radiation beam B passes through a projection system PS which focuses the beam onto a target portion C of a substrate W. By means of a second positioning device PW and a position sensor IF (e.g., an interferometric device, a linear encoder or a capacitive sensor), the substrate table WT can be accurately moved, e.g. in order to position different target portions C in the path of the radiation beam B. Similarly, e.g. after mechanical retrieval from a mask library or during a scan, a first positioning device PM and another position sensor (not explicitly depicted in FIG. 1) can be used to accurately position the mask MA relative to the path of the radiation beam B. Generally, movement of the mask table MT can be realized by means of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning) forming part of the first positioning device PM. Similarly, movement of the substrate table WT or “substrate support” can be realized by using a long-stroke module and a short-stroke module forming part of the second positioning device PW. In the case of a stepper (as opposed to a scanner), the mask table MT can be connected only to a short-stroke actuator or can be fixed. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 can be used to align the mask MA with the substrate W. Although the substrate alignment marks as illustrated occupy dedicated target portions, the marks can be located in the spaces between the target portions (these marks are called scribe alignment marks). Similarly, in the case where more than one die is provided on the mask MA, the mask alignment marks can be located between the dies.

[0046] The apparatus depicted can be used in at least one of the following modes:

[0047] 1. In a step mode, the mask table MT or “mask support” and the substrate table WT or “substrate support” are kept substantially stationary while the entire pattern imparted to the radiation beam is projected onto the target portion C in one go (i.e., single static exposure). Subsequently, the substrate table WT or “substrate support” is displaced in the X and / or Y direction so that different target portions C can be exposed. In the step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.

[0048] 2. In the scanning mode, the mask table MT or “mask support” and the substrate table WT or “substrate support” are scanned synchronously while the pattern imparted to the radiation beam is projected onto the target portion C (i.e., single dynamic exposure). The speed and direction of the substrate table WT or “substrate support” relative to the mask table MT or “mask support” can be determined by the magnification (reduction ratio) and image inversion characteristics of the projection system PS. In the scanning mode, the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, while the length of the scanning movement determines the height (in the scanning direction) of the target portion.

[0049] 3. In another mode, the mask table MT or “mask support” holding the programmable patterning device is kept substantially stationary, and the substrate table WT or “substrate support” is moved or scanned while the pattern imparted to the radiation beam is projected onto the target portion C. In this mode, a pulsed radiation source is typically employed and the programmable patterning device is updated as required after each movement of the substrate table WT or “substrate support” or between successive radiation pulses during the scan. This operating mode can be readily applied to maskless lithography using a programmable patterning device such as a programmable mirror array of the type mentioned above.

[0050] Combinations and / or variations of the usage modes described above or completely different usage modes can also be employed.

[0051] In the illustrated embodiment, the lithographic apparatus further includes an inspection tool IT according to the present invention. Such an inspection tool IT can for example enable the determination of characteristics of structures present on or in the region of interest of the substrate W processed by the lithographic apparatus. In an embodiment, as will be discussed in more detail below, the inspection tool can include an electron beam source for inspecting the substrate. In an embodiment, the second positioning device PW can be configured to position the substrate W within the operating range of the inspection tool IT. In such an embodiment, the inspection tool IT can for example be configured to determine characteristics of the mentioned structures, such as electrical characteristics, material characteristics and / or geometric characteristics. In an embodiment, this information can subsequently be provided to the control unit of the lithographic apparatus and used during the exposure process, for example by controlling one or more of the illumination system, the projection system or the positioning device based on this information.

[0052] In the illustrated embodiment, the lithographic apparatus can be configured to apply DUV radiation of the radiation beam. In this case, the patterning device MA can be a transmissive patterning device and the projection system PS can include one or more lenses.

[0053] Alternatively, a lithographic apparatus according to the invention may be configured to apply EUV radiation of a radiation beam. In such a case, the patterning device MA may be a reflective patterning device and the projection system PS may include one or more mirrors. In such an embodiment, the apparatus may include one or more vacuum chambers for accommodating the illumination system IL and / or the projection system PS.

[0054] Alternatively, a lithographic apparatus may be configured to apply an electron beam as the radiation beam to pattern a substrate W. Such a lithographic apparatus may for example include an electron beam apparatus according to the invention for patterning the substrate W. In an embodiment of such an apparatus, as will be explained in more detail below, a charged particle beam (in particular, an electron beam) is converted into a plurality of sub-beams that can be steered towards the substrate W in order to expose a desired portion of the substrate W. According to the invention, a charged particle beam lithographic apparatus includes a deflector unit configured to form a plurality of sub-beams in such a way that the plurality of sub-beams irradiate the surface of the substrate W at different incident angles.

[0055] According to one aspect of the invention, an electron beam apparatus is provided. Figure 1B An embodiment of such an electron beam apparatus is schematically shown in. Figure 1B An electron beam apparatus 100 according to the invention is schematically shown, the apparatus including an electron beam source 110 for generating an electron beam (e.g., a collimated electron beam 120).

[0056] In an embodiment, the electron beam source may be configured to generate an expanding electron beam. Such an expanding electron beam may be collimated by a collimator lens or a collimator lens system of the electron beam source to generate a collimated electron beam 120. In the embodiment shown, the electron beam 120 is provided to a beam conversion unit 130, which is configured to convert the electron beam 120. In particular, in the embodiment shown, the beam conversion unit 130 includes a hole array 130.1 and a deflector unit 130.2. According to the invention, the hole array 130.1 is configured to generate a plurality of sub-beams 122 from the electron beam 120. In an embodiment of the invention, such a hole array 130.1 may include (e.g., include a two-dimensional through-hole array) a perforated plate, and each through-hole provides a hole for generating one sub-beam.

[0057] In an embodiment of the invention, the hole array 130.1 may include a series arrangement of two or more hole arrays. In such an arrangement, the hole array 130.1 may for example include a first hole array that blocks portions of the electron beam to generate a plurality of sub-beams. In such an arrangement, the hole array may include a lens array for focusing the sub-beams and a second hole array for generating a plurality of sub-beams from each sub-beam.

[0058] According to the present invention, the beam conversion unit 130 includes a deflector unit 130.2 configured to deflect one or more of the generated sub-beams 122. As will be explained in more detail below, there are various options for implementing such a deflector unit 130.2. Although shown as discrete components in Figure 1B it should be noted that the aperture array 130.1 and the deflector unit 130.2 can be integrated into a single unit having both the functions of generating multiple sub-beams and deflecting one or more of the sub-beams.

[0059] In an embodiment, the beam conversion unit may further include a focusing function, such as enabling the sub-beams to be focused. Such focusing can be implemented individually for each sub-beam or for a group of multiple sub-beams.

[0060] In the illustrated embodiment, the electron beam device 100 according to the present invention further includes a projection system 140 configured to project the multiple sub-beams onto an object 150 (e.g., a substrate such as a semiconductor substrate). In an embodiment, the projection system 140 may include, for example, an objective lens for focusing the sub-beams onto the surface of the object 150.

[0061] In an embodiment, the projection system 140 may further include a scanning deflector lens or system for scanning the multiple sub-beams across the surface of the object.

[0062] According to the present invention, the deflector unit 130.2 of the electron beam device 100 is configured to deflect the multiple sub-beams 122 or one or more of the sub-beams 122 in such a way that the multiple sub-beams irradiate the object at different incident angles. This is schematically shown by reference numeral 124 in Figure 1B it.

[0063] The electron beam device according to the present invention can be applied to various different purposes.

[0064] In an embodiment of the present invention, the electron beam device according to the present invention is applied to an inspection tool, such as an inspection tool for inspecting a sample or a substrate (e.g., a semiconductor substrate). Thus, in an embodiment of the present invention, there is provided an inspection tool including the electron beam device according to the present invention. It can be appreciated that inspection tools using an electron beam source are well known. Examples of such tools include, for example, SEM (scanning electron microscope).

[0065] Figure 2A Such a well-known electron beam-based inspection tool 10 is schematically shown in it. The illustrated inspection tool 10 includes an electron beam source 11, which is also referred to as the electron beam source 11.

[0066] Such an electron beam source 11 is well-known and can be configured to project an electron beam 12 onto an area of an object 13 (e.g., a substrate). In the illustrated embodiment, the object 13 is mounted to an object stage 13.2 by means of a mounting mechanism 13.4 (e.g., a fixing mechanism such as a screw) or a clamping mechanism (e.g., a vacuum chuck or an electrostatic chuck). The area of the object onto which the electron beam is projected may also be referred to as a sample. Such an electron beam source 11 can be used, for example, to generate an electron beam 12 having an energy in the range of less than 0.2 keV to 100 keV. The electron beam source 11 typically may have one or more lenses for focusing the electron beam 12 onto a spot having a diameter of about 0.4 nm to 5 nm. In an embodiment, the electron beam source 11 may further include one or more scanning coils or deflector plates that can deflect the electron beam 12. Thereby, the electron beam 12 can be deflected, for example, along the X-axis and the Y-axis (perpendicular to the X-axis and the Z-axis) (the XY plane is parallel to the surface of the object), such that an area of the object can be scanned.

[0067] When such an electron beam 12 irradiates the surface, interactions on the surface and with the material below the surface will occur, causing both radiation and electrons to be emitted from the surface after exposure. Typically, when the electron beam 12 interacts with the sample, the electrons constituting the beam will lose energy within a teardrop-shaped volume (referred to as the interaction volume) via scattering and absorption. The energy exchange between the electron beam and the sample will typically result in a combination of the following:

[0068] - Emission of secondary electrons by inelastic scattering,

[0069] - Emission of electrons reflected or backscattered from the interaction volume by elastic scattering interactions with the sample,

[0070] - X-ray emission, and

[0071] - Emission of electromagnetic radiation, for example, in the range from deep UV to IR.

[0072] The latter emission of electromagnetic radiation is generally referred to as cathodoluminescence light, or CL light.

[0073] Typically, the inspection tool 10 further includes detectors 15 and 15.1, both of which can be used to detect secondary electrons and backscattered electrons. In an embodiment, the detector 15 is used to detect secondary electrons, while the detector 15.1 is used to detect backscattered electrons emitted by the sample. In FIG. 2, the arrow 14 indicates the emitted secondary electrons or backscattered electrons.

[0074] In the arrangement as shown, the inspection tool further includes a control unit 17 or a processing unit such as a microprocessor, a computer, etc., for processing the emitted secondary electrons or backscattered electrons detected by the detectors 15 and 15.1.

[0075] In the arrangement shown, the control unit 17 includes an input 17.2 for receiving a signal 15.2 from detectors 15, 15.1, the signal 15.2 representing detected secondary or backscattered electrons emitted.

[0076] In the arrangement shown, the control unit may also have an output 17.4 for outputting a control signal 11.2 for controlling the electron beam source 11. In an embodiment, the control unit 17 may control the electron beam source 11 to project the electron beam 12 onto an area of interest of an object (e.g., a semiconductor substrate) to be inspected.

[0077] In an embodiment, the control unit 17 may be configured to control the electron beam source 11 to scan the area of interest.

[0078] In a known electron beam inspection tool, the electron beam 12 will typically irradiate the object 13 or the surface of the object at a predetermined angle. The electron beam 12 may, for example, strike the surface at a 90-degree angle (i.e., perpendicular to the surface).

[0079] It is also known to use multiple electron beams for inspecting an object such as a semiconductor substrate. In such an arrangement, the multiple electron beams are configured to irradiate different parts of the area of interest and can thus scan or probe these different parts simultaneously. In a known arrangement of such a multi-beam inspection tool, the multiple electron beams are configured to irradiate the surface of the object at the same angle.

[0080] According to an embodiment of the present invention, there is provided an electron beam device configured to provide a plurality of sub-beams for irradiating the surface of the object, whereby the plurality of sub-beams are configured to irradiate the object or the surface of the object at different incident angles.

[0081] Figure 2B An inspection tool according to the present invention is schematically shown, including such an electron beam device according to the present invention. Figure 2BSchematically shown is an inspection tool 300 according to the present invention. The inspection tool 300 includes an electron beam device 100 according to the present invention for generating a plurality of sub-beams 124, and the plurality of sub-beams are configured to irradiate an object 313 at different incident angles. As schematically shown, the electron beam device 100 includes a source conversion module 130 and a projection system 140 as discussed above. In the illustrated embodiment, the object 313 is mounted to an object stage 313.2 by means of a mounting mechanism 313.4 (such as a fixing mechanism or a clamping mechanism (such as a vacuum chuck or an electrostatic chuck)). As schematically shown, the inspection tool 300 further includes a detector 315, which is configured to detect electrons emitted by the object in response to applying the sub-beam 124 to the surface of the object 313 (such as a semiconductor substrate). Depending on the application, the detector 315 may include one or more detectors for detecting different types of emissions caused by the interaction of the sub-beam 124 with the object, and such emissions include, for example, one or more of secondary electrons, backscattered electrons, X-ray emissions, or emissions of electromagnetic radiation. In the illustrated embodiment, the detector 315 includes a detector 315.2 for detecting secondary electrons and a detector 315.1 for detecting backscattered electrons emitted by the object 313.

[0082] In an embodiment, the detector 315 applied to the inspection tool according to the present invention may include a plurality of detector elements, and the plurality of detector elements are respectively used to detect the emitted radiation caused by the interaction of the object with the plurality of sub-beams 124.

[0083] In the illustrated embodiment, the inspection tool further includes a control unit 317 or a processing unit such as a microprocessor, a computer, etc., for processing the emitted secondary electrons or backscattered electrons detected by the detector 315.

[0084] In the illustrated arrangement, the control unit 317 includes an input terminal 317.2 for receiving signals 315.3 from the detectors 315.1, 315.2, and the signals 315.3 represent the detected emitted radiation, such as secondary electrons or backscattered electrons.

[0085] In the illustrated arrangement, the control unit may further have an output terminal 317.4 for outputting a control signal 311.2 for controlling the electron beam device 100. In an embodiment, the control unit 317 may control the electron beam device 100 to project the sub-beam 124 onto an area of interest of the object to be inspected (such as a semiconductor substrate). In an embodiment, the control unit 317 may be configured to control the electron beam device 100 to scan the area of interest.

[0086] Figures 3A and 3B schematically depict a top view and a cross-sectional view of an inspection tool 50 according to an embodiment of the present invention. Such an inspection tool 50 may, for example, have the functions of the inspection tool 300 discussed above. The illustrated embodiment includes a housing 51 and a pair of load ports 52 that serve as interfaces to receive an object to be inspected and output the inspected object. The illustrated embodiment further includes an object transfer system called an EFEM (Equipment Front End Module) 53 that is configured to handle and / or convey an object to the load ports and handle and / or convey an object from the load ports. In the illustrated embodiment, the EFEM 53 includes a transporter robot 54 that is configured to transfer an object between the load ports of the inspection tool 50 and a load lock 55. The load lock 55 is an interface between the atmospheric conditions that occur outside the housing 51 and in the EFEM and the vacuum conditions that occur in the vacuum chamber 56 of the inspection tool 50. In the illustrated embodiment, the vacuum chamber 56 includes an electron beam device 100 according to the present invention that is configured to project a plurality of sub-beams onto an object to be inspected (such as a semiconductor substrate or a wafer). The inspection tool 50 further includes a positioning device 58 that is configured to displace the object 59 relative to the sub-beams generated by the electron beam device 100. In an embodiment, the positioning device may include a series arrangement of a plurality of positioners, such as an XY stage for positioning the object in a substantially horizontal plane and a Z stage for positioning the object in a vertical direction.

[0087] In an embodiment, the positioning device may include a combination of a coarse positioner and a fine positioner, the coarse positioner being configured to provide coarse positioning of the object over a relatively large distance and the fine positioner being configured to provide fine positioning of the object over a relatively small distance.

[0088] In an embodiment, the positioning device 58 further includes an object stage for holding the object during an inspection process performed by the inspection tool 50. In such an embodiment, the object 59 may be clamped to the object stage by a clamp such as an electrostatic chuck. Such a clamp may be integrated into the object stage.

[0089] By using an inspection tool according to the present invention (as schematically shown in Figure 2B, the inspection tool in FIGS. 3A and 3B), an object (e.g., a sample or a semiconductor substrate) can be inspected by a plurality of sub-beams that irradiate the object at different incident angles. As will be explained in more detail below, such inspection can evaluate certain parameters of the inspected object in a more detailed and accurate manner. An inspection tool such as an electron beam inspection tool is, for example, used to inspect structures on a semiconductor substrate, thereby determining specific parameters of the structure. Such parameters can include, for example, critical dimension (CD), line edge roughness (LER), line width roughness (LWR), sidewall angle (SWA), overlap (OVL), etc. Based on such determined parameters, a process performed by, for example, a tool or device used to generate the structure can be subsequently evaluated. As an example, the quality of an exposure process performed by a lithography apparatus (e.g., a lithography apparatus schematically shown in Figure 1A can be evaluated. As an example, the exposure process can, for example, result in the generation of a grating or a grating-like structure, and thereby the quality of the obtained grating can be evaluated by determining parameters such as CD-uniformity, LER, LWR, or SWA using an electron beam inspection tool.

[0090] In an embodiment of the present invention, there is provided an inspection method for inspecting an object (e.g., a semiconductor substrate) using a plurality of sub-beams that irradiate the object at different incident angles.

[0091] Figure 4A and Figure 4B Schematically illustrates such an inspection method applied to inspect the sidewall angle (SWA) of a structure.

[0092] Figure 4A Schematically shows a structure 400, including a layer 410 and a line or linear structure 420 (e.g., representing a grating line), such a line 420 being manufactured, for example, by an exposure process performed by a lithography apparatus and then by a development process. The line 420 can be made of, for example, a resist material, which is, for example, different from the material of the layer 410. The shown line 420 has a non-zero sidewall angle SWA on both sides of the line. Figure 4A Further schematically shows 3 sub-beams, namely relatively small electron beams 430.1, 430.2, 430.3 configured to irradiate the structure 400 at different incident angles. In the shown embodiment, the sub-beams 430.1 to 430.3 irradiate the surface of the structure at corresponding angles (e.g., -10, 0, 10 degrees) with respect to an optical axis 440 considered to be perpendicular to the surface 400.1 of the structure. In the shown embodiment, the sub-beams 430.1 to 430.3 are spaced apart by a distance P, which is also referred to as the pitch between different sub-beams. Further assume that the structure 400 is scanned by the three sub-beams by displacing the sub-beams relative to the structure 400 in the indicated Y direction. Figure 4BSchematically shows the analog response signals that can be received when the structure 400 is scanned by three sub-beams 430.1 to 430.3 in the Y direction. In particular, the response signal S1 (as a function of time t) represents the signal that can be received by a detector or detector element configured to detect the response of the structure due to its interaction with the sub-beam 430.3. The response signal S2 (as a function of time t) represents the signal that can be received by a detector or detector element configured to detect the response of the structure due to its interaction with the sub-beam 430.2, and the response signal S3 (as a function of time t) represents the signal that can be received by a detector or detector element configured to detect the response of the structure due to its interaction with the sub-beam 430.1. It should be noted that for a given sub-beam layout with respect to the structure and the indicated scanning direction, the sub-beam 430.3 will be the first sub-beam to irradiate the line 420, and the sub-beam 430.1 will be the last sub-beam to irradiate the line. As can be seen from Figure 4B it can be seen that the angle at which the sub-beam irradiates the object being inspected affects the received response signal. For the given example, as can be seen from signals S1 and S3, an asymmetric signal is obtained when the sub-beam irradiates the structure 400 at a non-zero incident angle. This asymmetry can be used to correct the effects of data resulting from the interaction of the electrons injected by the primary beam with the material and geometry being studied. Thus, irradiating the structure to be inspected at different angles (i.e., using sub-beams that irradiate the object at different incident angles) provides additional data that can be applied to more accurately determine the actual parameters or characteristics to be inspected or determined (such as the sidewall angle SWA of the grating lines). Figure 5A and Figure 5B Schematically illustrates an inspection method for a structure 500 similar to the structure 400, where the structure 500 includes a layer 510 and a line 520 having an asymmetric sidewall angle on top of the layer 510. In particular, the sidewall angle on the right side of the line 520 is substantially equal to zero. When such a structure 500 is scanned by the same sub-beams 430.1 to 430.3, the analog response signals S4 to S6 (solid lines) as shown in Figure 5B can be obtained. Figure 5B The dashed-line curves in

[0093] correspond to the curves S1, S2, and S3, respectively.

[0094] The inspection method according to the present invention (wherein a sample including a structure, such as a semiconductor substrate, is inspected using a plurality of sub-beams that irradiate the sample at different incident angles) can also be applied to probe the depth of certain features of the structure.

[0094] This method is schematically illustrated in Figure 6A and Figure 6B

[0095] Figure 6A Structure 600 is schematically shown, including a buried layer 610, which includes features 610.1, such as metals or metal contacts. The buried layer 610 is covered by a layer 620, which is covered by a resist layer 630 including vias 630.1. Such a structure may be encountered, for example, when preparing to create holes that connect to the feature 610.1 through the layer 620, for example, by applying an etchant to the vias 630.1. In the case of scanning such a structure using two sub-beams 640.1 and 640.2 along the Y direction (i.e., sub-beams that irradiate the structure at different incident angles, such as +10 degrees and -10 degrees relative to the surface 630.2 perpendicular to the structure 600), response signals S8 and S7 as shown in Figure 6B can be obtained respectively. Thus, when the sample and the sub-beams are displaced relative to each other in the Y direction, signal S7 represents the interaction between the sub-beam 640.2 and the sample, while signal S8 represents the interaction between the sub-beam 640.1 and the sample. In the illustrated embodiment, it is assumed that the sub-beams have sufficient energy to generate a sufficient amount of backscattered electrons from the feature 610.1. Both signals S7 and S8 include a combination of response signals emitted by the feature 610.1 (referred to as signals S71 and S81), and response signals obtained from the interaction of the sub-beams with the vias 630.1 (referred to as signals S72 and S82). Therefore, signals S72 and S82 can be attributed to secondary electrons generated when the sub-beams 640.1 and 640.2 interact with the surface 630.2 and the exposed surface of the layer 620 in the vias 630.1. As can be seen in the graphs S7 and S8, the difference in the incident angles of the sub-beams causes different position shifts ΔY1 and ΔY2 between the signals caused by the buried feature 610.1 (signals S71 and S81) and the signals caused by the vias 630.1 (signals S72 and S82). Based on the position shifts ΔY1 and ΔY2 and the incident angles, the depth of the feature 610.1 can then be determined, in particular, the distance in the Z direction between the feature 610.1 and the vias 630.1. It can be noted that this method of determining the distance between two features is similar to the known parallax method used in astronomy, where the distance between two celestial bodies is determined by observing the celestial bodies from different angles.

[0096] Relative to the example shown in Figure 6A and Figure 6B it can be noted that in the case where the vias 630.1 and the feature 610.1 are aligned, i.e., in the case where the distance ΔY shown in Figure 6A is zero, the measurement results using a single sub-beam irradiated at a non-zero incident angle will be sufficient to determine the depth of the structure 610.1. (Note that in this case, for two sub-beams with incident angles that are mirror images of each other with respect to the perpendicular to the surface (e.g., +10 degrees and -10 degrees), the time shift ΔT is substantially the same).

[0097] In Figure 6A the case where the distance ΔY shown in Figure 6A is not equal to zero, the depth of the structure 610, and the distance ΔY representing the overlap between the through hole 630.1 and the feature 610.1 can be determined based on two measurement results (i.e., the measurement results using the sub-beams 640.1 and 640.2).

[0098] As already indicated above, in an embodiment, the present invention provides an electron beam device configured to generate a plurality of sub-beams that irradiate an object at different incident angles. According to the present invention, such a plurality of sub-beams can be generated by means of a beam conversion unit including a hole array and a deflector unit. Such a beam conversion unit can be implemented in various ways.

[0099] Figure 7A A first embodiment of a beam conversion unit that can be applied to an electron beam device according to the present invention is schematically shown. Figure 7A A cross-sectional side view of a beam conversion unit 700 including a hole array 710 and a deflector unit 720 is schematically shown. The hole array 710 can be a plate-shaped member including a plurality of holes 710.1 (e.g., circular holes), and the hole array 710 is configured to interact with the electron beam 730 so as to block a part of the electron beam 730, while other parts 740 can pass through the holes 710.1, thus forming sub-beams 740. The sub-beams 740 can then propagate through the deflector unit 720. In the illustrated embodiment, the deflector unit 720 includes a plurality of electrode assemblies 720.1, and the plurality of electrode assemblies include one or more electrodes to deflect the received sub-beams. In the illustrated embodiment, each hole 710.1 in the hole array 710 can have a corresponding electrode assembly 720.1 for deflecting the sub-beam passing through the hole. By deflecting the sub-beams 740, the sub-beams no longer propagate in a direction parallel to the optical axis 750 of the electron beam 730.

[0100] Figure 7B and Figure 7C is schematically depicted Figure 7A a top view of the corresponding hole array 710 and deflector unit 720 of the beam conversion unit 700. Figure 7B A top view of a hole array 710 including a plurality of holes 710.1 for forming a plurality of sub-beams is schematically shown. The generated sub-beam pattern can be, for example, square or hexagonal. Figure 7CA top view schematically showing a deflector unit 720, the deflector unit including a plurality of electrode assemblies 720.1. In the illustrated embodiment, each electrode assembly includes four electrodes, such as electrodes 720.11, 720.12, 720.13, and 720.14, which may be individually connected to a voltage source 760, for example. It should be noted that the use of four electrodes should be regarded as an example, and other numbers of electrodes, such as more than four electrodes, may equally be applied. By controlling one or more voltages applied to different electrode assemblies, the deflection of each sub-beam in the sub-beams 740 can be individually controlled and a desired deflection angle can be provided for the sub-beams.

[0101] It is worth mentioning that the aperture array 710 and the deflector unit 720 may be integrated in a single unit by means of MEMS technology, for example. In such an embodiment, the beam conversion unit may be configured in a multi-layer arrangement, each layer having a specific function. In such an arrangement, one layer may have a focusing function, for example, while one or more other layers may have a deflector function, for example. Additional layers may be applied to correct astigmatism, for example.

[0102] Figure 8 A cross-sectional side view schematically depicting a second embodiment of a beam conversion unit 800 that may be applied to an electron beam device according to the present invention. As schematically shown, the beam conversion unit 800 includes a first aperture array 810 having the same function as the aperture array 710 shown in Figure 7A ; that is, the first aperture array blocks a part of the electron beam 830 and allows other parts of the electron beam to pass through the apertures 810.1 of the aperture array to form sub-beams 840. The beam conversion unit 800 further includes a second aperture array including a plurality of apertures 820.1, the plurality of apertures being configured to respectively receive the sub-beams generated by the apertures 810.1 of the first aperture array 810. In the illustrated embodiment, the apertures 820.1 of the second aperture array 820 are displaced in the Y direction relative to the corresponding apertures 810.1 of the first aperture array. In the illustrated embodiment, the apertures 820.1 may also be slightly larger than the corresponding apertures 810.1. In such an embodiment, the displacement refers to the feature that the centers of the apertures 820.1 are located at different distances from the optical axis 850 in the indicated Y direction. In such an arrangement, when the aperture array is powered by a suitable voltage source, an electric field is generated, and the electric field has a component that deflects the sub-beams 840 in the Y direction.

[0103] In an embodiment of the present invention, a combination of the deflector units 720 and 820 may also form a deflector unit.

[0104] The third embodiment may be, for example, by Figure 8is achieved by combining a hole array such as hole array 810 with one relatively large hole or a plurality of relatively large holes arranged below the hole array 810 (instead of hole array 820). In such an embodiment, the hole array 810 can be maintained at a first voltage, while the array including one or more relatively large holes is maintained at a second voltage different from the first voltage. Such an arrangement will also result in curvature in the electric field between the upper hole array and the lower hole array including one or more relatively large holes, and such curvature causes deflection in the Y direction.

[0105] The fourth embodiment can be achieved, for example, by applying a common deflector unit for all sub-beams arranged below one or more hole arrays, so that the sub-beams enter an objective lens arranged further downstream at an angle with respect to the optical axis. Such an arrangement can be used to arrange a total deflection angle common to all sub-beams, and the total deflection angle is superimposed on the individual deflection angles generated by one or more arrays.

[0106] Figure 9 Schematically illustrates the arrangement of a 5x5 sub-beam 950 that can be generated using an electron beam device according to the present invention. In the illustrated embodiment, a two-dimensional array of 5x5 sub-beams is generated using a source conversion module 900, which is configured to generate 5x5 sub-beams using a matrix of 5x5 holes 900.1 and deflect at least some of the sub-beams. In the illustrated embodiment, the generated sub-beams have different incident angles on the object 910. In this example, the sub-beams in group A have an incident angle of -10 degrees, the sub-beams in group B have an incident angle of -5 degrees, the sub-beams in group C have an incident angle of 0 degrees, the sub-beams in group D have an incident angle of +5 degrees, and the sub-beams in group E have an incident angle of +10 degrees. Therefore, the sub-beams arranged in rows extending in the X direction have substantially constant incident angles, while the sub-beams arranged in rows extending in the Y direction have different incident angles. As the illustrated embodiment further schematically illustrates an objective lens 920, which can be used to focus the sub-beams 950 onto the object 910. It should be noted that such an objective lens will also change the angle of the sub-beams; in particular, the objective lens can be used to magnify the angle of the sub-beams. Therefore, the relatively small deflection angle generated by the hole array can still generate a relatively large deflection angle, such as ~10 degrees, at the object.

[0107] As Figure 9 illustrated, a beam of sub-beams 950 can be applied, for example, to scan a structure present on an object when it is applied to an inspection tool according to the present invention. When such a structure will, for example, include grating lines extending in the X direction, such lines will then be sequentially detected by the set of sub-beams A to E, enabling an image of the structure to be generated based on the sub-beams or the set of sub-beams illuminating the structure at different incident angles.

[0108] As discussed above, such a sub-beam 950 can be obtained by converting an electron beam generated by an electron beam source using a beam conversion unit. Generally, such a beam conversion unit can be configured to convert the electron beam of the electron beam source into, for example, a plurality of sub-beams arranged in an n x n matrix.

[0109] As indicated above, in an embodiment of the present invention, an electron beam device can be configured to subdivide an electron beam into a plurality of sub-beams using a first aperture array. Each of these sub-beams can then be converted into a beam of sub-beams using a beam conversion unit. Such a beam of sub-beams thus produced can also be referred to as a sub-beam column. In an embodiment of the present invention, such a sub-beam column can include its own optical components of the sub-beam column for converting (e.g., focusing or scanning) the beam.

[0110] As discussed above, an electron beam device according to the present invention can advantageously be used in an inspection tool according to the present invention, and is thus capable of inspecting a structure from different angles while only requiring one scan of the structure.

[0111] An electron beam device according to the present invention can also advantageously be applied in an exposure device according to the present invention in order to pattern an object (e.g., a resist layer on a semiconductor substrate). Such a device can also be referred to as a lithographic exposure device. Lithographic exposure devices using a plurality of sub-beams or sub-beam columns to pattern an object are well known. However, by using an electron beam device according to the present invention in an exposure device according to the present invention, electron beams or sub-beams having different angles of incidence can be used to pattern an object. It should be understood that this enables more accurate patterning, which can subsequently result in a more accurate structure deposited or produced on the object.

[0112] In an embodiment of an exposure device according to the present invention, the exposure device includes an electron beam device according to the present invention and a positioning device, such as the positioning device PW discussed above. Such a positioning device can, for example, include one or more linear or planar motors for long-stroke positioning of the object relative to the plurality of sub-beams produced. Such a positioning device can also, for example, include one or more actuators for short-stroke (more accurate) positioning of the object relative to the sub-beams produced.

[0113] Alternatively, the object to be patterned can be kept in a substantially stationary position while a plurality of sub-beams or multiple beams of sub-beams are scanned across the object.

[0114] Thus, in an embodiment of the present invention, the exposure device can be configured to pattern an object by providing a relative displacement of the object and the sub-beams in a direction perpendicular to the optical axis of the electron beam device of the exposure device, by means of a plurality of sub-beams having different angles of incidence. Such a relative displacement can be referred to as scanning or a scanning process in the context of the present invention.

[0115] To provide an object with a specific pattern, certain parts of the object need to be exposed to one or more sub-beams in a sub-beam, while other parts cannot be exposed. To achieve such selective exposure during scanning of the object by multiple sub-beams, it is necessary to be able to shield the object or parts of the object from the sub-beams.

[0116] Such controlled shielding of the object from one or more sub-beams in a sub-beam can be achieved using a sub-beam blanking array.

[0117] The operating principle of such a sub-beam blanking array is schematically shown in Figure 10 below.

[0118] Figure 10 Schematically shown is a beam conversion unit 1000 that can be applied herein. The beam conversion unit is configured to generate a plurality of sub-beams 1010, and the plurality of sub-beams are configured to irradiate an object 1020 at different incident angles. As shown in Figure 10 The embodiment shown also includes a sub-beam blanking array 1030. The sub-beam blanking array includes an electrode array 1030.1 and a hole array 1030.2. The hole array is also referred to as a sub-beam baffle array 1030.2. In the embodiment shown, when a suitable supply voltage is supplied to one or more of the deflector electrodes, the electrode array 1030.1 is configured such that one or more of the sub-beams 1010 are deflected so as to fall on the sub-beam baffle array 1030.2 instead of passing through the holes of the hole array 1030.2. This is illustrated in Figure 10 for sub-beam 1010.1. By providing suitable voltages to electrodes 1030.11 and 1030.12, sub-beam 1010.1 can be deflected (indicated by the dashed arrow 1040) so as to fall on the sub-beam baffle array 1030.2 instead of passing through the hole 1030.21 of the hole array 1030.2. As seen from the object 1020, the sub-beam 1010 can thus be "opened" or "closed" by the sub-beam blanking array 1030.

[0119] Thus, during scanning of an object (such as an object provided with a resist layer sensitive to charged particles such as electrons), individual sub-beams can be opened or closed to selectively expose the object to one or more of the sub-beams 1010, thereby creating a desired pattern on the object.

[0120] It should be understood that Figure 10It is only used to illustrate the principle of selectively blocking one or more sub-beams in order to generate a desired exposure pattern on an object (such as a semiconductor substrate). The specific layout of different components can be different. In particular, the distance between the electrode array 1030.1 and the sub-beam baffle array 1030.2 can be relatively large. In an embodiment, the electrode array 1030.1 can also be integrated in the beam conversion unit 1000.

[0121] In an embodiment, the deflection unit as described can also be used for blanking.

[0122] As will be clear to those skilled in the art, the inspection tool and exposure device according to the present invention can include various other components for converting the electron beam or sub-beam used. Such components are generally referred to as optical components because they have the same function as an optical inspection tool or exposure device and can, for example, include well-known projection lenses or arrays of projection lenses, objective lenses or arrays of objective lenses, or collimating lenses or arrays of collimating lenses, or condenser lenses or arrays of condenser lenses.

[0123] For the sake of completeness, Figure 11 a more detailed embodiment of an electron beam inspection tool including such components is shown in.

[0124] Figure 11 A cross-sectional view of a known inspection tool 200 is schematically depicted, which inspection tool includes an electron beam source called an electron gun 210 and an imaging system 240.

[0125] The electron gun 210 includes an electron source 212, a suppressor electrode 214, an anode 216, a set of apertures 218, and a condenser 220. The electron source 212 can be a Schottky emitter or a modified Schottky emitter as discussed above. By the positive voltage of the anode 216, an electron beam 202 can be extracted, and the electron beam 202 can be controlled by using selectable apertures 218, which can have different aperture sizes to remove unnecessary electron beams outside the apertures. In order to shape the electron beam 202, the diverging characteristics of the condenser 220 are used for the electron beam 202, which also changes the magnification. Figure 10 The condenser 220 shown in can be, for example, an electrostatic lens, which can shape the electron beam 202. On the other hand, the condenser 220 can also be a magnetic lens or a combined lens.

[0126] The imaging system 240 may include, for example, a blanker, a set of apertures 242, a detector 244, four sets of deflectors 250, 252, 254, and 256, a coil 262, a magnetic yoke 260, and electrodes 270. The electrodes 270 may be used to delay and deflect the electron beam 202 and may also have an electrostatic lens function. In addition, the coil 262 and the yoke 260 may be configured as a magnetic objective lens.

[0127] The deflectors 250 and 256 may be applied to scan the electron beam 202 within a large field of view, and the deflectors 252 and 254 may be used to scan the electron beam 202 within a small field of view. All of the deflectors 250, 252, 254, and 256 may control the scanning direction of the electron beam 202. The deflectors 250, 252, 254, and 256 may be electrostatic deflectors or magnetic deflectors. The opening of the yoke 260 faces the sample 300 so that the sample 300 is immersed in the magnetic field. On the other hand, the electrodes 270 are placed below the opening of the yoke 260, and thus the sample 300 will not be damaged. To correct the chromatic aberration of the electron beam 202, the retarder 270, the sample 300, and the yoke 260 or portions thereof may form a lens to minimize the chromatic aberration of the electron beam 202. The inspection tool 200 further includes a processing unit 310, which may be implemented as a processor, a microprocessor, a controller, or a computer, for example. The processing unit 310 is configured to receive response signals from one or more detectors (such as the detector 244) of the inspection tool and process the response signals into a scanned or inspected structure, or an image of the sample 300.

[0128] The embodiments may be further described using the following aspects:

[0129] 1. An electron beam device, comprising:

[0130] - an electron beam source configured to generate an electron beam;

[0131] - a beam conversion unit, comprising:

[0132] - an aperture array configured to generate a plurality of sub-beams from the electron beam;

[0133] - a deflector unit configured to deflect one or more of the plurality of sub-beams;

[0134] - a projection system configured to project the plurality of sub-beams onto the object, wherein the deflector unit is configured to deflect one or more of the plurality of sub-beams so as to irradiate the object at different incident angles.

[0135] 2. The electron beam device according to aspect 1, further comprising an object stage arranged to hold the object.

[0136] 3. The electron beam device tool according to aspect 1 further includes one or more lenses, and the one or more lenses are arranged upstream of the hole array.

[0137] 4. The electron beam device according to any one of the foregoing aspects, wherein the projection system includes an objective lens configured to project the plurality of sub - beams onto the object.

[0138] 5. The electron beam device according to any one of the foregoing aspects, wherein the projection system includes a scanning deflector unit configured to scan the plurality of sub - beams across the surface of the object.

[0139] 6. The electron beam device according to any one of the foregoing aspects, wherein the deflector unit is integrated in the hole array.

[0140] 7. The electron beam device according to any one of the foregoing aspects, wherein the deflector unit includes a plurality of electrodes configured to deflect the corresponding plurality of sub - beams.

[0141] 8. The electron beam device according to aspect 6 or 7, wherein the plurality of electrodes of the deflector unit are arranged at or near the corresponding plurality of holes of the hole array.

[0142] 9. The electron beam device according to any one of aspects 6 to 8, wherein the beam conversion unit includes a multi - layer MEMS array, and the multi - layer MEMS array includes the hole array and the deflector unit.

[0143] 10. The electron beam device according to aspect 2 further includes a positioning device for positioning the object stage relative to the optical axis of the electron beam source.

[0144] 11. The electron beam device according to any one of the foregoing aspects, wherein the hole array includes a first hole array and a second hole array, the first hole array is configured to generate a plurality of sub - beams from the electron beam, and the second hole array is configured to receive the plurality of sub - beams and generate the plurality of sub - beams.

[0145] 12. The electron beam device according to any one of the foregoing aspects, wherein the hole array includes a plurality of holes for generating the corresponding plurality of sub - beams, and wherein the deflector unit includes an additional hole array, and the additional hole array includes a corresponding plurality of additional holes for receiving the corresponding plurality of sub - beams.

[0146] 13. The electron beam device according to aspect 12, wherein the plurality of holes and the plurality of additional holes are shifted relative to the optical axis of the device.

[0147] 14. The electron beam device according to aspect 13, wherein the plurality of holes are arranged in a two-dimensional array, and the plurality of additional holes are arranged in another two-dimensional array.

[0148] 15. The electron beam device according to aspect 14, wherein the shift between the first hole associated with the first sub-beam and the first additional hole is different from the shift between the second hole associated with the second sub-beam and the second additional hole.

[0149] 16. The electron beam device according to any one of aspects 12 to 15, wherein during use, the hole array and the additional hole array are maintained at different voltages.

[0150] 17. The electron beam device according to any one of the foregoing aspects, further comprising a control unit for controlling the operation of the electron beam source and / or the beam conversion unit.

[0151] 18. An inspection tool comprising the electron beam device according to any one of the foregoing aspects.

[0152] 19. The inspection tool according to aspect 18, wherein the inspection tool is configured to scan the object with the plurality of sub-beams.

[0153] 20. The inspection tool according to aspect 18, further comprising a detector configured to receive response signals from the object in response to scanning the object with the plurality of sub-beams.

[0154] 21. The inspection tool according to aspect 20, wherein the detector is configured to detect one or more of secondary electrons, backscattered electrons, X-ray radiation, or electromagnetic radiation.

[0155] 22. The inspection tool according to any one of aspects 19 to 21, further comprising a scanning deflector unit for scanning the plurality of sub-beams across the object.

[0156] 23. The inspection tool according to any one of aspects 19 to 22, further comprising a positioning device for displacing the object relative to the plurality of sub-beams so as to scan the plurality of sub-beams across the object.

[0157] 24. An exposure device comprising the electron beam device according to any one of aspects 1 to 17.

[0158] 25. The exposure device according to aspect 24, wherein the exposure device is configured to pattern the object using the plurality of sub-beams.

[0159] 26. The exposure apparatus according to aspect 24 or 25 further includes a sub-beam blanking array configured to selectively block one or more of the plurality of sub-beams during patterning the object.

[0160] 27. A method of inspecting an object, the method comprising:

[0161] - generating a plurality of sub-beams from an electron beam source, the sub-beams being configured to irradiate the object at different incident angles;

[0162] - detecting a response signal from the object in response to irradiating the object with the plurality of sub-beams;

[0163] - processing the response signal to determine a characteristic of the object.

[0164] 28. The method according to aspect 27, wherein the object is a semiconductor substrate.

[0165] 29. The method according to aspect 28, wherein the object includes a line structure, and wherein the characteristic includes at least one of line edge roughness, line width roughness, or sidewall angle.

[0166] 30. The method according to aspect 28, wherein the object includes a buried structure, and wherein the characteristic includes the depth of the buried structure.

[0167] 31. An electron beam apparatus, comprising:

[0168] - an electron beam source configured to generate an electron beam;

[0169] - a beam conversion unit, comprising:

[0170] - a hole array configured to generate a plurality of sub-beams from the electron beam;

[0171] - a deflector unit configured to deflect one or more groups of the plurality of sub-beams;

[0172] - a projection system configured to project the plurality of sub-beams onto an object, wherein the deflector unit is configured to deflect one or more groups of the plurality of sub-beams so as to irradiate the object at different incident angles, and each sub-beam in a group has substantially the same incident angle on the object.

[0173] 32. A method of inspecting an object, the method comprising:

[0174] - Generating a plurality of sub - beams from an electron - beam source, one or more groups of the plurality of sub - beams being configured to irradiate the object at different incident angles, each sub - beam in a group having substantially the same incident angle on the object;

[0175] - Detecting response signals from the object generated in response to irradiating the object with the plurality of sub - beams;

[0176] - Processing the response signals to determine characteristics of the object.

[0177] Although reference may be made specifically herein to the use of a lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin - film magnetic heads, etc. Those skilled in the art will appreciate that in the context of such alternative applications, any use herein of the terms “wafer” or “die” may be considered synonymous with the more general terms “substrate” or “target portion” respectively. The substrate mentioned herein may be processed in, for example, a coating - development system (a tool that typically coats a resist layer onto a substrate and develops the exposed resist), a metrology tool, and / or an inspection tool, either before or after exposure. Where applicable, the disclosures herein can be applied to these and other substrate - processing tools. Additionally, the substrate may be processed more than once, for example, in order to create a multi - layer IC, such that the term “substrate” as used in the present invention may also refer to a substrate that already includes multiple processed layers.

[0178] Although embodiments of the invention may have been specifically referred to above in the context of optical lithography, it should be understood that the invention can be used in other applications (e.g., imprint lithography) and is not limited to optical lithography, where the context permits. In imprint lithography, the topography in the patterning device defines the pattern created on the substrate. The topography of the patterning device can be pressed into a resist layer supplied to the substrate, where the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist is cured, the patterning device is removed from the resist, leaving the pattern therein.

[0179] As used herein, the terms “radiation” and “beam” encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g., having a wavelength of or about 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., having a wavelength in the range of 5 nm to 20 nm), as well as particle beams, such as ion beams or electron beams.

[0180] The term "lens" (where the context permits) can refer to any type of optical element or combination of optical elements of various types, including refractive, reflective, magnetic, electromagnetic, electrostatic, and combined optical elements.

[0181] Although specific embodiments of the invention have been described above, it should be understood that the invention may be practiced in other ways different from those described. For example, the invention may take the form of a computer program comprising one or more sequences of machine-readable instructions describing a method as disclosed above; or a data storage medium (e.g., semiconductor memory, magnetic disk, or optical disk) having such a computer program stored therein.

[0182] The foregoing description is intended to be illustrative, not restrictive. Accordingly, those skilled in the art will appreciate that the described invention may be modified without departing from the scope of the claims set forth below.

Claims

1. An electron beam device, comprising: An electron beam source configured to generate an electron beam; A beam conversion unit, the beam conversion unit comprising: A hole array configured to generate a plurality of sub-beams from the electron beam; A deflector unit configured to deflect a plurality of sub-beam groups, each sub-beam group having one or more sub-beams selected from the plurality of sub-beams; A projection system configured to project the plurality of sub-beam groups onto an object, wherein the deflector unit is configured to deflect the plurality of sub-beam groups to propagate non-parallel to the optical axis of the electron beam and non-parallel to each other, so that each group of the plurality of sub-beam groups has a desired deflection angle to irradiate the object at different incident angles, and each sub-beam in a group has substantially the same incident angle on the object.

2. An electron beam device, comprising: An electron beam source configured to generate an electron beam; A beam conversion unit, the beam conversion unit comprising: A hole array configured to generate a discrete plurality of sub-beams from the electron beam; and A deflector unit configured to deflect a plurality of sub-beam groups, each sub-beam group having one or more sub-beams selected from the plurality of sub-beams; and A projection system configured to project the plurality of sub-beam groups onto an object, wherein the deflector unit and the projection system are configured together to deflect and cause the plurality of sub-beam groups to be incident on the object, such that the net incident angle of one or more sub-beams of a first sub-beam group in the plurality of sub-beam groups on the object is different from the net incident angle of one or more sub-beams of a second sub-beam group in the plurality of sub-beam groups on the object, and such that the one or more sub-beams of the first sub-beam group and the one or more sub-beams of the second sub-beam group sequentially scan the same structure of the object to obtain corresponding response signals, so as to determine the characteristics of the object based on the response signals and the net incident angles.

3. The electron beam device according to claim 1 or 2, further comprising an object stage configured to hold the object.

4. The electron beam device according to claim 1 or 2, further comprising one or more lenses arranged upstream of the hole array.

5. The electron beam device according to any one of the preceding claims, wherein the projection system comprises an objective lens configured to project the plurality of sub-beams onto the object.

6. The electron beam device according to any one of the preceding claims, wherein the projection system comprises a scanning deflector unit configured to scan the plurality of sub-beams across the surface of the object.

7. The electron beam device according to any one of the preceding claims, wherein the deflector unit is integrated in the hole array.

8. The electron beam device according to any one of the preceding claims, wherein the deflector unit comprises a plurality of electrodes configured to deflect the corresponding plurality of sub-beams.

9. The electron beam device according to claim 7 or 8, wherein the plurality of electrodes of the deflector unit are arranged at or near corresponding ones of the plurality of holes of the hole array.

10. The electron beam device according to claim 7 or 8, wherein the beam conversion unit includes a multi-layer MEMS array, and the multi-layer MEMS array includes the hole array and the deflector unit.

11. The electron beam device according to claim 3, further comprising positioning means for positioning the object stage relative to the optical axis of the electron beam source.

12. The electron beam device according to any one of the preceding claims, wherein the hole array includes a first hole array and a second hole array, the first hole array being configured to generate a plurality of sub-beams from the electron beam, and the second hole array being configured to receive the plurality of sub-beams and generate the plurality of sub-beams.

13. The electron beam device according to claim 1 or 2, wherein the hole array includes a plurality of holes for generating the corresponding plurality of sub-beams, and wherein the deflector unit includes an additional hole array, the additional hole array including a corresponding plurality of additional holes for receiving the corresponding plurality of sub-beams.

14. The electron beam device according to claim 13, wherein the plurality of holes and the plurality of additional holes are displaced relative to the optical axis of the electron beam device.

15. The electron beam device according to claim 14, wherein the plurality of holes are arranged in a two-dimensional array, and the plurality of additional holes are arranged in an additional two-dimensional array.

16. The electron beam device according to claim 15, wherein the displacement between a first hole associated with a first sub-beam and a first additional hole is different from the displacement between a second hole associated with a second sub-beam and a second additional hole.

17. The electron beam device according to claim 13, wherein during use, the hole array and the additional hole array are maintained at different voltages.

18. The electron beam device according to claim 1 or 2, further comprising a control unit for controlling the operation of the electron beam source and / or the beam conversion unit.

19. An inspection tool comprising the electron beam device according to any one of claims 1 to 18.

20. The inspection tool according to claim 19, wherein, The inspection tool is configured to scan the object using the plurality of sub-beams.

21. The inspection tool according to claim 19, further comprising a detector configured to receive a response signal from the object in response to scanning the object using the plurality of sub-beams.

22. The inspection tool according to claim 21, wherein the detector is configured to detect one or more of secondary electrons, backscattered electrons, X-ray radiation, or electromagnetic radiation.

23. The inspection tool according to any one of claims 20 to 22, further comprising a scanning deflector unit for scanning the plurality of sub-beams across the object.

24. The inspection tool according to any one of claims 20 to 23, further comprising positioning means for displacing the object relative to the plurality of sub-beams so as to scan the plurality of sub-beams across the object.

25. An exposure apparatus, comprising an electron beam apparatus according to any one of claims 1 to 18.

26. The exposure apparatus according to claim 25, wherein the exposure apparatus is configured to pattern the object using the plurality of sub-beams.

27. The exposure apparatus according to claim 25 or 26, further comprising a sub-beam blanking array configured to selectively block one or more of the plurality of sub-beams during patterning of the object.

28. A method of inspecting an object, the method comprising: generating a plurality of sub-beams from an electron beam source, the sub-beams being configured to sequentially irradiate the same structure of the object at different incident angles; detecting response signals sequentially generated from the same structure of the object in response to sequentially irradiating the same structure of the object with the plurality of sub-beams; processing the response signals to determine characteristics of the object.

29. A method of inspecting an object, the method comprising: generating an electron beam from an electron beam source; generating a discrete plurality of sub-beam groups from the electron beam using a hole array of an electron beam apparatus; deflecting the plurality of sub-beam groups using a deflector unit of the electron beam apparatus, each sub-beam group having one or more sub-beams selected from the plurality of sub-beams; projecting the plurality of sub-beam groups onto the object using a projection system of the electron beam apparatus, wherein the deflector unit and the projection system together deflect and cause the plurality of sub-beam groups to be incident on the object such that the net incident angle of one or more sub-beams of a first sub-beam group of the plurality of sub-beam groups on the object is different from the net incident angle of one or more sub-beams of a second sub-beam group of the plurality of sub-beam groups on the object, and such that one or more sub-beams of the first sub-beam group and one or more sub-beams of the second sub-beam group sequentially scan the same structure of the object; detecting corresponding response signals sequentially generated from the same structure of the object in response to sequentially irradiating the same structure of the object with the plurality of sub-beam groups; processing the response signals to determine characteristics of the object.

30. The method according to claim 28 or 29, wherein the object is a semiconductor substrate.

31. The method according to claim 30, wherein the object includes a line structure, and wherein the characteristics include at least one of line edge roughness, line width roughness, or sidewall angle.

32. The method according to claim 30, wherein the object includes a buried structure, and wherein the characteristics include the depth of the buried structure.

33. A computer-readable medium, comprising one or more sequences of machine-readable instructions describing a method, the method comprising: generating a plurality of sub-beams from an electron beam source, the sub-beams being configured to sequentially irradiate the same structure of the object at different incident angles; detecting response signals sequentially generated from the same structure of the object in response to sequentially irradiating the same structure of the object with the plurality of sub-beams; processing the response signals to determine characteristics of the object.

34. A computer-readable medium, comprising one or more sequences of machine-readable instructions describing a method, the method comprising: generating an electron beam from an electron beam source; Using an electron beam device, a plurality of discrete sub-beam groups are generated from the electron beam for a hole array; Using a deflector unit of the electron beam device to deflect the plurality of sub-beam groups, each sub-beam group having one or more sub-beams selected from the plurality of sub-beams; Using a projection system of the electron beam device to project the plurality of sub-beam groups onto an object, wherein the deflector unit and the projection system together deflect and cause the plurality of sub-beam groups to be incident on the object such that the net incident angle of one or more sub-beams of a first sub-beam group in the plurality of sub-beam groups on the object is different from the net incident angle of one or more sub-beams of a second sub-beam group in the plurality of sub-beam groups on the object, and such that one or more sub-beam groups of the first sub-beam group and one or more sub-beams of the second sub-beam group sequentially scan the same structure of the object; Detecting corresponding response signals sequentially generated from the same structure of the object in response to sequentially irradiating the same structure of the object with the plurality of sub-beam groups; Processing the response signals to determine the characteristics of the object.

35. The computer-readable medium according to claim 33 or 34, wherein the object is a semiconductor substrate.

36. The computer-readable medium according to claim 35, wherein the object includes a linear structure, and wherein the characteristics include at least one of line edge roughness, line width roughness, or sidewall angle.

37. The computer-readable medium according to claim 35, wherein the object includes a buried structure, and wherein the characteristics include the depth of the buried structure.

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