A container configured to receive a radiation beam, having an internal structure configured to be cooled for contaminant removal

Abstract

An assembly includes a container configured to receive a radiation beam. The assembly includes an internal structure forming a portion of the container or enclosed within the container, and a temperature control system configured to control a temperature of the internal structure to be within a range of 77 K to 140 K.

Description

Cross-reference to related applications

[0001] This application claims priority to EP application 23218202.2, filed on December 19, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to methods and components including containers with internal structures configured for cooling to remove contaminants. Specifically, it may relate to components for contaminant removal provided within photolithography or metrology apparatus. Background Technology

[0003] A lithography apparatus is a machine configured to apply a desired pattern onto a substrate. For example, a lithography apparatus can be used to manufacture integrated circuits (ICs). A lithography apparatus can project a pattern (often referred to as a “design layout” or “design”) onto a layer of radiation-sensitive material (resist) provided on a substrate (e.g., a wafer), for example at a patterning device (e.g., a mask).

[0004] To project patterns onto a substrate, photolithography apparatuses can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the feature that can be formed on the substrate. Typical wavelengths currently used are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. Compared to photolithography apparatuses using radiation with wavelengths in the range of 4 to 20 nm (e.g., 6.7 nm or 13.5 nm), photolithography apparatuses using extreme ultraviolet (EUV) radiation with wavelengths in the range of 4 to 20 nm can be used to form smaller features on the substrate.

[0005] Low-k1 lithography can be used to process features smaller than the classical resolution limit of a lithography apparatus. In this process, the resolution formula can be expressed as CD = k1 × λ / NA, where λ is the radiation wavelength used, NA is the numerical aperture of the projection optics in the lithography apparatus, CD is the "critical size" (typically the smallest feature size printed, but in this case, half a pitch), and k1 is an empirical resolution factor. Generally, the smaller k1 is, the more difficult it is to reproduce patterns on the substrate that are similar in shape and size to those planned by the circuit designer to achieve specific electrical functionality and performance. To overcome these difficulties, complex fine-tuning steps can be applied to the lithography projection apparatus and / or design layout. These include, but are not limited to, optimization of NA, custom illumination schemes, use of phase-shifting patterning equipment, various optimizations of the design layout such as optical proximity correction (OPC, sometimes also called "optical and process correction"), or other methods generally defined as "resolution enhancement techniques" (RET). Alternatively, tight control loops used to control the stability of the lithography apparatus can be used to improve pattern reproduction at low k1.

[0006] In photolithography and other manufacturing processes, frequent measurements of the created structures are desirable, for example, for process control and verification. Various tools are known for performing these measurements, including scanning electron microscopes (commonly used to measure critical dimensions (CD)) and specialized tools for measuring overlay and the alignment accuracy of two layers in a device. Recently, various forms of scatterometers have been developed for use in the photolithography field.

[0007] The manufacturing process can be, for example, photolithography, etching, deposition, chemical mechanical planarization, oxidation, ion implantation, diffusion, or a combination of two or more of these.

[0008] Examples of known scatterers typically rely on providing a dedicated measurement target. For instance, one approach might require a target in the form of a simple grating, large enough that the measurement beam produces a spot smaller than the grating (i.e., underfilling). In so-called reconstruction methods, the properties of the grating can be calculated by simulating the interaction between the scattered radiation and a mathematical model of the target structure. The parameters of the model are tuned until the simulated interaction produces a diffraction pattern similar to that observed from a real target.

[0009] Besides reconstructing the shape of the measurement feature, diffraction-based overlay measurements can also be performed using such a device, as described in published patent application US2006066855A1. Diffraction-based overlay measurements using dark-field imaging with diffraction orders enable overlay measurements on small targets. These targets can be smaller than the illumination spot and can be surrounded by the product structure on the wafer. Examples of dark-field imaging measurements can be found in numerous published patent applications, such as, for example, US2011102753A1 and US20120044470A. Multiple gratings can be measured in a single image using a composite grating target. Known scatterometers tend to use light in the visible or near-infrared (IR) wavelength range, which requires the grating pitch to be much coarser than the actual product structure of interest. Such product features can be defined using deep ultraviolet (DUV), extreme ultraviolet (EUV), or X-ray radiation with shorter wavelengths. Unfortunately, these wavelengths are often unavailable or unusable for measurement.

[0010] On the other hand, the dimensions of modern product structures are so small that they cannot be imaged using optical metrology techniques. Small features include, for example, those formed through multiple patterning processes and / or pitch multiplication. Therefore, targets used for high-volume metrology typically use features much larger than the product whose overlay error or critical dimension is the property of interest. Measurement results are only indirectly correlated with the dimensions of the actual product structure and may be inaccurate because the measured target does not suffer the same distortions under optical projection in a photolithography apparatus and / or different treatments in other steps of the manufacturing process. While scanning electron microscopy (SEM) can directly resolve these modern product structures, SEM is more time-consuming than optical measurements. Furthermore, electrons cannot penetrate thicker process layers, making them less suitable for metrology applications. Other techniques, such as measuring electrical properties using contact pads, are also known, but they only provide indirect evidence of the actual product structure.

[0011] By reducing the radiation wavelength used during measurement, smaller structures can be resolved, thereby improving sensitivity to structural changes and / or further penetration into the product structure. One such method for generating appropriate high-frequency radiation (e.g., hard X-rays, soft X-rays, and / or EUV radiation) can use pump radiation (e.g., infrared IR radiation) to excite the generating / target medium, thereby generating emitted radiation, optionally including the generation of higher harmonics (HHG) of the high-frequency radiation.

[0012] Photolithography patterning exposure and measurement are typically performed in a vacuum. One factor that can affect the lifespan of components within these vacuum apparatuses is the presence of contaminants such as hydrocarbons and water. The short-wavelength radiation used in photolithography can break down hydrocarbons, potentially leading to carbon deposits on surfaces within the apparatus. These deposits can be particularly noticeable in areas where high-intensity incident radiation is present. Water molecules present in the vacuum chamber can also be fractured by short-wavelength radiation and can cause optical surface degradation, for example, through oxidation. Contaminant deposition on guiding radiation elements, such as optical components, can significantly degrade their performance. For example, they can cause reductions in reflectivity, wavefront error, and so on.

[0013] Despite powerful vacuum pump systems, vacuum chambers may still have some background partial pressure of contaminants, such as hydrocarbons and water. Therefore, maintaining the surfaces within the container (such as optics) free from contaminant deposits, for example, by carbon buildup or oxidation, may require additional measures. Maintaining surface cleanliness in a vacuum can be achieved, for example, by introducing purge gases. The purge gas flow can be guided and shaped so that contaminants can be swept away from the optics. Furthermore, some purge gases can create a clean environment by etching or slowing down oxidation.

[0014] If the surface of an optical device is contaminated, its performance will be degraded, and cleaning may be required. This cleaning can typically be performed off-site. This may require associated downtime for optical switching and equipment. Sometimes in-situ cleaning can be performed, such as using specially selected plasmas. However, not all contaminant deposits are cleanable, such as silicon-based deposits, for example. Summary of the Invention

[0015] According to one aspect of the present disclosure, a component is provided that includes a container configured to receive a radiation beam. The component also includes an internal structure forming part of or enclosing within the container, and a temperature control system configured to control the temperature of the internal structure within a range of 77 K to 140 K.

[0016] Optionally, the container can be configured to operate at a pressure of 0.05 mbar or lower, or 0.01 mbar or lower, during component operation.

[0017] Optionally, the temperature control system can be configured to control the temperature of the internal structure within the range of 90 K to 140 K, 90 K to 130 K, 100 K to 125 K, and essentially 100 K.

[0018] Optionally, the radiation beam may include one or more wavelengths in the range of 1 nm to 20 nm, or 1 nm to 10 nm, or 10 nm to 20 nm, or 9 nm to 18 nm, or 13.5 nm.

[0019] Optionally, the internal structure can be configured to capture contaminants on at least one surface of the internal structure.

[0020] Optionally, the internal structure can be configured to remove captured contaminants from the container.

[0021] Alternatively, pollutants may include hydrocarbons.

[0022] Alternatively, the contaminant may include water.

[0023] Optionally, the component may also include optical elements within the container.

[0024] Optionally, the optical component may include a reflective optical component, and the radiation beam guided by the optical component may include a reflected radiation beam.

[0025] Optionally, the optical components can be configured to guide one or more wavelengths of radiation in the range of 1 nm to 20 nm.

[0026] Optionally, the internal structure can be configured to be cooled during the process of depressurizing the container.

[0027] Optionally, the internal structure may include a textured surface.

[0028] Alternatively, the textured surface may include at least one of nanoparticles or metal aerogels.

[0029] Alternatively, the internal structure can be enclosed within a container and can be moved within the container.

[0030] Optionally, the internal structure can be moved into and out of the container.

[0031] Optionally, the movable internal structure can be configured to insert into the radiation propagation path during the descent of the container when the radiation beam is off, and to retract from the propagation path before the radiation beam is turned on.

[0032] Optionally, the internal structure may include multiple insertable rods.

[0033] Optionally, the internal structure may include an extendable body for increasing the surface area of ​​the internal structure.

[0034] Optionally, the internal structure may form part of the container and part of the inner wall of the container.

[0035] Optionally, the temperature control system may include a motor for powering the cooling device, wherein the motor is separated from the container by a mechanical decoupling device.

[0036] Alternatively, the mechanical decoupler can be a heat exchanger.

[0037] Alternatively, the motor can be configured to drive the compressor pump.

[0038] Optionally, the internal structure can be a shell that encloses the internal space. The shell may include: an input end configured to be positioned in the propagation path of the radiation beam, such that the radiation beam is guided into the internal space of the shell; and an output end configured to be positioned in the transmission path of the radiation beam, such that the radiation beam is guided out of the internal space of the shell.

[0039] Optionally, the input end may include an elongated structure comprising a hollow core arranged along the propagation path of the radiation beam, such that the radiation beam propagates along the hollow core of the elongated structure.

[0040] Optionally, the output end may include an elongated structure comprising a hollow core arranged along the propagation path of the radiation beam, such that the radiation beam propagates along the hollow core of the elongated structure.

[0041] Optionally, the enclosure can be configured to capture contaminants on at least one surface adjacent to the interior space in order to remove them from the interior space.

[0042] Optionally, the temperature control system may include a liquid nitrogen cooling system.

[0043] According to another aspect of this disclosure, a measuring device is provided, including the components described above.

[0044] According to another aspect of this disclosure, an inspection apparatus is provided, including the components described above.

[0045] According to another aspect of this disclosure, an exposure apparatus is provided, including the components described above.

[0046] According to another aspect of this disclosure, a photolithography apparatus is provided, including the components described above.

[0047] According to another aspect of this disclosure, a photolithography unit is provided, including the apparatus described above. Attached Figure Description

[0048] The embodiments will now be described by way of example only with reference to the accompanying schematic diagrams, wherein: - Figure 1(a) depicts a schematic overview of the photolithography apparatus; - Figure 1(b) depicts a schematic overview of the photolithography system; - Figure 2 A schematic overview of the photolithography unit is described; - Figure 3 A schematic representation of overall photolithography is depicted, illustrating the collaboration between three key technologies to optimize semiconductor manufacturing; - Figure 4 The scattering measurement device is illustrated schematically. - Figure 5 The transmission scattering measurement device is illustrated schematically. - Figure 6 A schematic representation of a measurement apparatus using EUV and / or SXR radiation is depicted; - Figure 7 A simplified schematic diagram of the irradiation source is depicted; - Figure 8 A schematic representation of a component used for cryogenic cooling within a container is depicted; - Figure 9 A graphical representation of a component used for cryogenic cooling via a housing is depicted; and - Figure 10 The graphs depict the vapor pressure of different types of gases as a function of temperature. Detailed Implementation

[0049] In this document, the terms “radiation” and “beam” are used to encompass all types of electromagnetic and particle radiation, including ultraviolet radiation (e.g., wavelengths of 365, 248, 193, 157, or 126 nm), EUV (extreme ultraviolet radiation, e.g., wavelengths in the range of about 5 to 100 nm), X-ray radiation, electron beam radiation, and other particle radiation.

[0050] As used herein, the terms “mask,” “mask,” or “patterning apparatus” can be broadly interpreted to refer to a general patterning apparatus that can be used to impart a patterned cross-section to an incoming radiation beam, corresponding to a pattern to be created in a target portion of a substrate. The term “optical valve” can also be used in this context. Examples of such patterning apparatuses, in addition to classic masks (transmissive or reflective masks, binary masks, phase-shifting masks, hybrid masks, etc.), include programmable mirror arrays and programmable LCD arrays.

[0051] Figure 1(a) schematically depicts a lithography apparatus LA. The lithography apparatus LA includes an irradiation system (also called an irradiator) IL configured to modulate a radiation beam B (e.g., UV radiation, DUV radiation, EUV radiation, or X-ray radiation), a mask support (e.g., a mask stage) T configured to support a patterning apparatus (e.g., a mask) MA and connected to a first positioner PM (configured to accurately position the patterning apparatus MA according to certain parameters), a substrate support (e.g., a wafer stage) WT configured to hold a substrate (e.g., a resist-coated wafer) W and connected to a second positioner PW (configured to accurately position the substrate support according to certain parameters), and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted by the radiation beam B by the patterning apparatus MA onto a target portion C (e.g., including one or more dies) of the substrate W.

[0052] In operation, the irradiation system IL receives a radiation beam from a radiation source SO (e.g., via a beam delivery system BD). The irradiation system IL may include various types of optical components, such as refractive, reflective, diffractive, magnetic, electromagnetic, electrostatic, and / or other types of optical components or any combination thereof, for guiding, shaping, and / or controlling the radiation. The irradiator IL may be used to modulate the radiation beam B to have a desired spatial and angular intensity distribution in its cross-section at the plane of the patterning device MA.

[0053] As used herein, the term “projection system” PS should be broadly understood to encompass all types of projection systems, including refractive, reflective, diffractive, reflective-refractive, distorting, magnetic, electromagnetic, and / or electrostatic optical systems or any combination thereof, as appropriate for the exposure radiation used and / or other factors such as the use of immersion or vacuum. Any use of the term “projection lens” herein may be considered synonymous with the more general term “projection system” PS.

[0054] A lithography apparatus LA can be of the type in which at least a portion of the substrate can be covered by a liquid (e.g., water) with a relatively high refractive index to fill the space between the projection system PS and the substrate W; this is also known as immersion lithography. More information on immersion technology is given in US6952253, which is incorporated herein by reference in its entirety.

[0055] The lithography apparatus LA can also be of the type having two or more substrate supports WT (also known as "dual-platform"). In such a "multi-platform" machine, the substrate supports WT can be used in parallel, and / or the subsequent exposure steps for preparing the substrate W can be performed on the substrate W located on one of the substrate supports WT, while another substrate W on the other substrate support WT is used to expose a pattern on the other substrate W.

[0056] In addition to the substrate support WT, the lithography apparatus LA may include a measurement platform. The measurement platform is arranged to hold sensors and / or cleaning equipment. The sensors may be arranged to measure the properties of the projection system PS or the properties of the radiation beam B. The measurement platform may hold multiple sensors. The cleaning equipment may be arranged to clean part of the lithography apparatus, such as part of the projection system PS or part of a system providing immersion liquid. The measurement platform may move below the projection system PS as the substrate support WT moves away from the projection system PS.

[0057] In operation, a radiation beam B is incident on a patterning apparatus (e.g., a mask) MA and patterned by a pattern (design layout) present on the patterning apparatus MA, which is held on a mask support T. After traversing the mask MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. The substrate support T can be precisely moved by means of a second locator PW and a position measurement system IF, for example, to position different target portions C in the path of the radiation beam B at focused and aligned positions. Similarly, a first locator PM and possibly another position sensor (not explicitly depicted in FIG. 1(a)) can be used to precisely position the patterning apparatus MA relative to the path of the radiation beam B. The patterning apparatus MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the illustrated substrate alignment marks P1, P2 occupy dedicated target portions, they can be located in the space between the target portions. When substrate alignment marks P1 and P2 are located between target portions C, these are called scribing alignment marks.

[0058] Figure 1(b) illustrates a lithography system including a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and supply the EUV radiation beam B to the lithography apparatus LA. The lithography apparatus LA includes an irradiation system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate stage WT configured to support a substrate W.

[0059] The irradiation system IL is configured to modulate the EUV radiation beam B before it is incident on the patterning apparatus MA. The irradiation system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. Together, the faceted field mirror device 10 and the faceted pupil mirror device 11 provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. In addition to or in place of the faceted field mirror device 10 and the faceted pupil mirror device 11, the irradiation system IL may include other mirrors or devices.

[0060] After being adjusted in this way, the EUV radiation beam B interacts with the patterning apparatus MA. Due to this interaction, a patterned EUV radiation beam B' is generated. The projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. For this purpose, the projection system PS may include a plurality of mirrors 13, 14, configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate stage WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B' to form an image with features smaller than the corresponding features on the patterning apparatus MA. For example, a reduction factor of 4 or 8 may be applied. Although the projection system PS is illustrated in FIG. 1 with only two mirrors 13, 14, the projection system PS may include a different number of mirrors (e.g., six or eight mirrors).

[0061] The substrate W may include a previously formed pattern. In this case, the photolithography apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the pattern previously formed on the substrate W.

[0062] A relative vacuum (i.e., a small amount of gas (e.g., hydrogen) at a pressure much lower than atmospheric pressure) can be provided in the radiation source SO, the irradiation system IL, and / or the projection system PS.

[0063] The radiation source SO shown in Figure 1 is of the type that can be referred to as a laser-generated plasma (LPP) source, for example. A laser system 1 (which may include, for example, a CO2 laser) is arranged to deposit energy into a fuel, such as tin (Sn) supplied from, for example, a fuel emitter 3, via a laser beam 2. Although tin is referenced in the following description, any suitable fuel can be used. The fuel may be, for example, in liquid form and may be, for example, a metal or alloy. The fuel emitter 3 may include a nozzle configured to guide tin, for example, along a trajectory toward the plasma-forming region 4 in the form of droplets. The laser beam 2 is incident on the tin at the plasma-forming region 4. The deposition of laser energy into the tin creates a tin plasma 7 at the plasma-forming region 4. During the de-excitation and recombination of electrons with ions from the plasma, radiation, including EUV radiation, is emitted from the plasma 7.

[0064] EUV radiation from the plasma is collected and focused by collector 5. Collector 5 includes, for example, a near-normal incident radiation collector 5 (sometimes more generally referred to as a normal incident radiation collector). Collector 5 may have a multi-layered mirror structure arranged to reflect EUV radiation (e.g., EUV radiation with a desired wavelength such as 13.5 nm). Collector 5 may have an elliptical configuration with two elliptical foci. As discussed below, the first focal point may be located at plasma formation region 4, and the second focal point may be located at intermediate focal point 6.

[0065] Laser system 1 can be spatially separated from radiation source SO. In this case, laser beam 2 can be delivered from laser system 1 to radiation source SO by means of a beam delivery system (not shown), which includes, for example, suitable directional mirrors and / or beam expanders and / or other optical devices. Laser system 1, radiation source SO and beam delivery system can be considered together as a radiation system.

[0066] The radiation reflected by collector 5 forms an EUV radiation beam B. The EUV radiation beam B is focused at intermediate focus 6 to form an image of the plasma present in plasma formation region 4 at intermediate focus 6. The image at intermediate focus 6 acts as a virtual radiation source for the irradiation system IL. The radiation source SO is arranged such that intermediate focus 6 is located at or near opening 8 in the enclosed structure 9 of the radiation source SO.

[0067] like Figure 2 As shown, a lithography apparatus LA can form part of a lithography unit LC, sometimes also called a lithography unit or (lithography) cluster. This LC typically also includes apparatus for performing pre- and post-exposure processes on a substrate W. Conventionally, these include a spin coater SC for depositing a resist layer, a developer DE for developing the exposed resist, a chiller CH for regulating the temperature of the substrate W (e.g., for regulating the solvent in the resist layer), and a baking plate BK. A substrate handler or robot RO picks up the substrate W from input / output ports I / O1, I / O2, moves them between different process units, and delivers the substrate W to the feed stage LB of the lithography apparatus LA. The equipment within the lithography unit (often collectively referred to as tracks) may be controlled by a track control unit TCU, which itself may be controlled by a supervisory control system SCS, which may also control the lithography apparatus LA, for example, via the lithography control unit LACU.

[0068] In photolithography, frequent measurements of the created structure are desirable, for example, for process control and verification. The tools used to perform these measurements are referred to as metrology tools (MTs). Different types of metrology tools (MTs) for performing such measurements are known, including scanning electron microscopes (SEMs) or various forms of scatterometer metrology tools (MTs). A scatterometer is a versatile instrument that allows the measurement of parameters of the photolithography process by placing a sensor in or near the pupil of the scatterometer objective (these measurements are often referred to as pupil-based measurements) or by placing a sensor in or near the image plane (in this case, these measurements are often referred to as image- or field-based measurements). Such scatterometers and associated measurement techniques are further described in patent applications US20100328655, US2011102753A1, US20120044470A, US20110249244, US20110026032, or EP1,628,164A, all of which are incorporated herein by reference in their entirety. The aforementioned scatterometer can measure gratings using light from hard X-rays (HXR), soft X-rays (SXR), extreme ultraviolet (EUV), visible to near-infrared (IR), and the IR wavelength range. If the radiation is hard or soft X-rays, the aforementioned scatterometer can optionally be a small-angle X-ray scattering measurement tool.

[0069] To ensure correct and consistent exposure of the substrate W by the photolithography unit LA, it is desirable to inspect the substrate to measure properties of the patterned structure, such as overlay errors between subsequent layers, line thickness, critical dimension (CD), structural shape, etc. For this purpose, inspection tools and / or measurement tools (not shown) may be included in the photolithography unit LC. If errors are detected, adjustments may be made, for example, to the exposure of subsequent substrates or other processing steps to be performed on the substrate W, particularly if the inspection is completed before other substrates W in the same batch or group are still to be exposed or processed.

[0070] An inspection apparatus (also referred to as a measurement apparatus) is used to determine the properties of a substrate W, particularly how the properties of different substrates W vary, or how the properties associated with different layers of the same substrate W change between layers. The inspection apparatus may alternatively be configured to identify defects on the substrate W, and may be, for example, part of a photolithography unit LC, or integrated into a photolithography apparatus LA, or even a stand-alone device. The inspection apparatus can measure the properties of latent images (images in the resist layer after exposure), semi-latent images (images in the resist layer after the PEB baking step), developed resist images (where exposed or unexposed portions of the resist have been removed), or even etched images (after pattern transfer steps such as etching).

[0071] In the first embodiment, the scatterer MT is an angle-resolved scatterer. In such a scatterer, a reconstruction method can be applied to the measured signal to reconstruct or calculate the properties of the grating. For example, this reconstruction can be performed by simulating the interaction between the scattered radiation and a mathematical model of the target structure and comparing the simulation results with the measurement results. The parameters of the mathematical model are adjusted until the simulated interaction produces a diffraction pattern similar to that observed from a real target.

[0072] In the second embodiment, the scatterer MT is a spectroscopic scatterer MT. In this spectroscopic scatterer MT, radiation emitted by a radiation source is directed onto the target, and reflected, transmitted, or scattered radiation from the target is directed to a spectroscopic detector that measures the spectrum of specularly reflected radiation (i.e., intensity based on wavelength). Using this data, for example through rigorous coupled-wave analysis and nonlinear regression, or by comparison with a simulated spectral library, the structure or profile of the target from the detected spectrum can be reconstructed.

[0073] In the third embodiment, the scatterer MT is an ellipsometer. An ellipsometer allows the determination of parameters of a photolithography process by measuring the scattered or transmitted radiation for each polarization state. This measurement device emits polarized light (such as linear, circular, or elliptical) by using, for example, a suitable polarization filter in the illumination section of the measurement device. A source suitable for the measurement device can also provide polarized radiation. Various embodiments of existing ellipsometers are described in U.S. Patent Applications 11 / 451,599, 11 / 708,678, 12 / 256,780, 12 / 486,449, 12 / 920,968, 12 / 922,587, 13 / 000,229, 13 / 033,135, 13 / 533,110, and 13 / 891,410, all of which are incorporated herein by reference.

[0074] In one embodiment of a scattering instrument (MT), the scattering instrument MT is adapted to measure the overlay of two misaligned gratings or periodic structures by measuring the reflectance spectrum and / or detecting asymmetry in the configuration, the asymmetry being related to the degree of overlay. Two (potentially overlaid) grating structures can be applied to two different layers (not necessarily consecutive layers) and can be formed at substantially the same location on the wafer. The scattering instrument can have a symmetrical detection configuration, for example, described in the co-owned patent application EP1,628,164A, such that any asymmetry is readily distinguishable. This provides a direct way to measure misalignment in gratings. Other examples involving overlay errors between two layers of a periodic structure when the target is measured by asymmetry of the periodic structure can be found in PCT patent application publication WO 2011 / 012624 or U.S. patent application US 20160161863, both of which are incorporated herein by reference in their entirety.

[0075] Other parameters of interest may be focus and dose. Focus and dose can be determined simultaneously by scattering measurements (or alternatively by scanning electron microscopy), as described in U.S. Patent Application US2011-0249244, which is incorporated herein by reference in its entirety. A single structure may be used that has a unique combination of critical size and sidewall angle measurements for each point in the focus energy matrix (FEM, also known as the focus exposure matrix). If these unique combinations of critical size and sidewall angles are available, the focus and dose values ​​can be uniquely determined from these measurements.

[0076] The measurement target can be an integral composite grating, formed via photolithography, primarily within a resist, but can also be formed after other manufacturing processes, such as etching. The pitch and linewidth of the structure within the grating may be largely dependent on the measurement optics (particularly the NA of the optics) to capture the diffraction order from the measurement target. As previously indicated, the diffraction signal can be used to determine the shift between two layers (also known as 'overlap') or to reconstruct at least a portion of the original grating produced by the photolithography process. This reconstruction can be used to provide guidance on the quality of the photolithography process and can be used to control at least a portion of the photolithography process. The target can have smaller sub-subdivisions configured to mimic the dimensions of functional portions of the design layout within the target. Due to these sub-subdivisions, the target's behavior will be more similar to the functional portions of the design layout, making the overall process parameter measurements more similar to the functional portions of the design layout. The target can be measured in either underfill or overfill modes. In underfill mode, the measurement beam generates a spot smaller than the overall target. In overfill mode, the measurement beam generates a spot larger than the overall target. In this overfilling mode, it may also be possible to measure different targets simultaneously, thereby determining different processing parameters at the same time.

[0077] The overall measurement quality of lithography parameters for a specific target is determined at least in part by the measurement scheme used to measure those parameters. The term "substrate measurement scheme" can include one or more parameters of the measurement itself, one or more parameters of one or more patterns being measured, or both. For example, if the measurement used in the substrate measurement scheme is a diffraction-based optical measurement, the one or more parameters measured can include the wavelength of the radiation, the polarization of the radiation, the angle of incidence of the radiation relative to the substrate, the radiation orientation relative to the pattern on the substrate, etc. One criterion for selecting a measurement scheme can be, for example, the sensitivity of one of the measurement parameters to handling variations. Further examples are described in U.S. Patent Application US2016-0161863 and published U.S. Patent Application US2016 / 0370717A1, both of which are incorporated herein by reference in their entirety.

[0078] Patterning in the photolithography (LA) apparatus is one of the most critical steps in the process, requiring highly accurate dimensional determination and placement of the structure on the substrate W. To ensure this high accuracy, three systems can be combined into a so-called "holistic" control environment, such as... Figure 3 The diagram illustrates this schematically. One of these systems is the lithography apparatus LA, which is (in fact) connected to the metrology tool MT (second system) and the computer system CL (third system). The key to this "holistic" environment is optimizing the collaboration between these three systems to enhance the overall process window and providing a tight control loop to ensure that the patterning performed by the lithography apparatus LA remains within the process window. The process window defines a range of process parameters (e.g., dose, focus, overlay) within which a specific manufacturing process will produce a defined result (e.g., a functional semiconductor device). Within this range, process parameters in the lithography or patterning process may be allowed to vary.

[0079] The computer system CL can use a portion of the design layout to be patterned to predict the resolution enhancement techniques to be used, and perform computational lithography simulations and calculations to determine which mask layouts and lithography setups achieve the maximum overall process window (within) the patterning process. Figure 3 (Depicted by double arrows in the first scale SC1). Resolution enhancement techniques can be arranged to match the patterning possibilities of the lithography apparatus LA. The computer system CL can also be used to detect where the lithography apparatus LA is currently operating within the process window (e.g., using input from the metrology tool MET) to predict whether defects may exist due to, for example, suboptimal processing (in... Figure 3 (This is depicted by the arrow pointing to "0" in the second scale SC2).

[0080] The measurement tool MT can provide input to the computer system CL for accurate simulation and prediction, and can provide feedback to the lithography apparatus LA to identify possible drift, for example, in the calibrated state of the lithography apparatus LA (in Figure 3 (Depicted by multiple arrows in the third scale SC3).

[0081] Many different types of measurement tools (MTs) are available for measuring structures created using photolithographic patterning apparatuses. MTs can interrogate structures using electromagnetic radiation. The properties of the radiation (e.g., wavelength, bandwidth, power) can affect the different measurement characteristics of the tool; shorter wavelengths generally allow for higher resolution. The radiation wavelength influences the resolution achievable by the measurement tool. Therefore, MTs with short-wavelength radiation sources are preferred for measuring structures with small-sized features.

[0082] Another way radiation wavelength can affect measurement characteristics is through-penetration depth and the transparency / opacity of the material under inspection at that wavelength. Depending on opacity and / or through-penetration depth, radiation can be used for transmission or reflection measurements. The type of measurement can affect whether information about the surface and / or interior of the structure / substrate is obtained. Therefore, through-penetration depth and opacity are another element to consider when selecting a radiation wavelength for a measurement tool.

[0083] To achieve high resolution measurements of lithographically patterned structures, measurement tools (MTs) with short wavelengths are preferred. This can include wavelengths shorter than the visible wavelength, such as those in the UV, EUV, and X-ray portions of the electromagnetic spectrum. Hard X-ray methods, such as transmission small-angle X-ray scattering (TSAXS), utilize the high resolution and high penetration depth of hard X-rays, and therefore can operate under transmission. On the other hand, soft X-rays and EUV do not penetrate the target very far, but may induce rich optical responses in the material being probed. This is likely due to the optical properties of many semiconductor materials and because the size of these structures is comparable to the probe wavelength. Therefore, EUV and / or soft X-ray measurement tools (MTs) can operate under reflection, for example, by imaging or by analyzing diffraction patterns from lithographically patterned structures.

[0084] For hard X-rays, soft X-rays, and EUV radiation, their application in high-volume manufacturing (HVM) applications may be limited due to the lack of available high-brightness radiation sources at the required wavelengths. In the case of hard X-rays, commonly used sources in industrial applications include X-ray tubes. X-ray tubes (including advanced X-ray tubes based on liquid metal anodes or rotating anodes, for example) may be relatively affordable and compact, but may lack the brightness required for HVM applications. High-brightness X-ray sources such as synchrotron light sources (SLS) and X-ray free-electron lasers (XFELs) currently exist, but their size (>100m) and high cost (hundreds of millions of euros) make them too large and expensive for metrology applications. Similarly, there is a lack of availability of sufficiently bright EUV and soft X-ray radiation sources.

[0085] An example of a measuring device such as a scatterometer is in Figure 4 Depicted in the image. It may include a broadband (e.g., white light) radiation projector 2 that projects radiation 5 onto a substrate W. The reflected or scattered radiation 10 is passed to a spectrometer detector 4, which measures the spectrum 6 of the specularly reflected radiation (i.e., measures the intensity I as a function of wavelength λ). This data is then processed, for example, through rigorous coupled-wave analysis and nonlinear regression or through... Figure 4The structure or profile of the detected spectrum is compared with the simulated spectral library shown at the bottom, and can be reconstructed by the processing unit PU. Typically, for reconstruction, the general form of the structure is known, and some parameters are assumed based on knowledge of the manufacturing process of the structure; only a few parameters of the structure need to be determined from scattering measurement data. This scatterer can be configured as a normal-incident scatterer or an oblique-incident scatterer.

[0086] exist Figure 5 The image depicts a transmission version of an example measuring device, such as... Figure 4 The scatterer is shown. The transmitted radiation 11 is passed to the spectrometer detector 4, which measures the spectrum 6, such as for... Figure 4 This is under discussion. Such a scatterer can be configured as a normal-incident scatterer or an oblique-incident scatterer. Optionally, the transmission version uses hard X-ray radiation with wavelengths <1 nm, optionally <0.1 nm, or optionally <0.01 nm.

[0087] As an alternative to optical measurement methods, the use of hard X-rays, soft X-rays, or EUV radiation, such as radiation having at least one of the following wavelength ranges: <0.01 nm, <0.1 nm, <1 nm, between 0.01 nm and 100 nm, between 0.01 nm and 50 nm, between 1 nm and 50 nm, between 1 nm and 20 nm, between 5 nm and 20 nm, and between 10 nm and 20 nm. An example of a measurement tool that operates within one of the wavelength ranges mentioned above is transmitted small-angle X-ray scattering (T-SAXS, as in US 2007224518A, the contents of which are incorporated herein by reference in their entirety). Profile (CD) measurements using T-SAXS are described in "Intercomparison between optical and X-ray scatterometry measurements of FinFET" by Lemaillet et al., published in the SPIE proceedings, page 8681, 2013. The discussion is in structures (a comparison between optical and X-ray scattering measurements of FinFET structures). It should be noted that the use of laser-generated plasma (LPP) X-ray sources is described in U.S. Patent Publication Nos. 2019 / 003988A1 and 2019 / 215940A1, both of which are incorporated herein by reference in their entirety. Reflectance measurement techniques using X-rays (GI-XRS) and extreme ultraviolet (EUV) radiation at grazing incidence can be used to measure the properties of thin films and layer stacks on substrates. Within the general field of reflectance measurement, angle measurement and / or spectroscopic techniques can be applied. In angle measurement, variations in the reflected beam at different incident angles can be measured. On the other hand, spectroreflectometers measure the wavelength spectrum reflected at a given angle (using broadband radiation). For example, EUV reflectometers have been used to inspect mask blanks before fabricating masks for EUV lithography (patterning apparatus).

[0088] The scope of applications may render the use of wavelengths in, for example, the hard X-ray, soft X-ray, or EUV domains insufficient. Published patent applications US 20130304424A1 and US 2014019097A1 (Bakeman et al. / KLA) describe hybrid metrology techniques in which measurements using X-rays and optical measurements at wavelengths in the 120 nm and 2000 nm range are combined to obtain measurements of parameters such as CD. CD measurements are obtained by coupling an X-ray mathematical model and an optical mathematical model through one or more common points. The contents of the cited US patent applications are incorporated herein by reference in their entirety.

[0089] Figure 6A schematic representation of the measuring device 302 is depicted, wherein the aforementioned radiation can be used to measure parameters of a structure on a substrate. Figure 6 The measurement device 302 proposed in the paper may be suitable for hard X-ray, soft X-ray and / or EUV domains.

[0090] Figure 6 The schematic physical arrangement of the measurement device 302, which includes a spectroscopic scatterer that optionally uses hard X-rays, soft X-rays, and / or EUV radiation at grazing incidence, is illustrated by way of example only. An alternative form of the inspection device may be provided in the form of an angle-resolved scatterer that can use radiation with normal or near-normal incidence similar to that of a conventional scatterer operating at longer wavelengths, and may also use radiation oriented at an angle greater than 1° or 2° to the direction parallel to the substrate. An alternative form of the inspection device may be provided in the form of a transmission scatterer. Figure 5 The configuration described herein is suitable for this inspection device.

[0091] The inspection apparatus 302 includes a radiation source or so-called irradiation source 310, an irradiation system 312, a substrate support 316, detection systems 318 and 398, and a measurement processing unit (MPU) 320.

[0092] In this example, the irradiation source 310 is used to generate EUV, hard X-ray, or soft X-ray radiation. The irradiation source 310 can be based on... Figure 6 The high harmonic generation (HHG) technique shown can also be other types of irradiation sources, such as liquid metal jet sources, inverse Compton scattering (ICS) sources, plasma channel sources, magnetic undulator sources, free electron laser (FEL) sources, compact storage ring sources, discharge-generated plasma sources, soft X-ray laser sources, rotating anode sources, solid anode sources, particle accelerator sources, microfocus sources, or laser-generated plasma sources.

[0093] HHG sources and other types of sources can have a gas target and can be a gas jet / nozzle source, capillary / fiber source, or gas chamber source. HHG sources and other types of sources can have a solid or liquid target. Although HHG sources with gas targets are described below, it is to be understood that the present invention is not limited to HHG sources with gas targets and can be used with HHG sources with solid or liquid targets as well as other types of sources with any target. Gas targets, solid targets, and liquid targets can be referred to as generation / target media.

[0094] Examples of HHC sources, such as Figure 6As shown, the main components of the radiation source are a pump radiation source 330 operable to emit pump radiation and a gas delivery system 332. Optionally, the pump radiation source 330 is a laser, and optionally, it is a pulsed high-power infrared or optical laser. The pump radiation source 330 can be, for example, a fiber-based laser with an optical amplifier, producing infrared radiation pulses that can last for, for example, less than 1 ns (1 nanosecond) per pulse, with a pulse repetition rate up to several megahertz, as desired. The wavelength of the infrared radiation can be in the range of 200 nm to 10 µm, for example, in the 1 μm (1 micrometer) region. Optionally, the laser pulse is delivered to the gas delivery system 332 as a first pump radiation 340, wherein in the gas, a portion of the radiation is converted to a higher frequency than the first radiation to become the emitted radiation 342. A gas supply 334 delivers a suitable gas to the gas delivery system 332, which is optionally ionized by a power source 336. The gas delivery system 332 can be a dicing tube.

[0095] The gas provided by the gas delivery system 332 defines a gas target, which can be a gas flow or a static volume. The gas can be, for example, air, neon (Ne), helium (He), nitrogen (N2), oxygen (O2), argon (Ar), krypton (Kr), xenon (Xe), carbon dioxide, and combinations thereof. These can be optional options within the same apparatus. The emitted radiation can contain multiple wavelengths. If the emitted radiation is monochromatic, measurement calculations (e.g., reconstruction) can be simplified, but generating radiation with several wavelengths is easier. The emission divergence angle of the emitted radiation can be wavelength-dependent. For example, when imaging structures of different materials, different wavelengths will provide different levels of contrast. For example, for the inspection of metallic or silicon structures, different wavelengths can be selected as wavelengths for imaging the characteristics of (carbon-based) resists or for detecting contamination in such different materials. One or more filtering devices 344 can be provided. For example, filters such as aluminum (Al) or zirconium (Zr) thin films can be used to cut the basic IR radiation to prevent further propagation into the inspection apparatus. A grating (not shown) can be provided to select one or more specific wavelengths from those generated wavelengths. Optionally, the irradiation source includes a space configured to be emptied, and a gas delivery system is configured to provide a gaseous target within that space. Optionally, some or all of the beam paths may be contained within a vacuum environment, noting that SXR and / or EUV radiation is absorbed as it propagates in air. Various components of the radiation source 310 and the irradiation optics 312 can be adjustable to achieve different measurement 'schemes' within the same apparatus. For example, different wavelengths and / or polarizations can be selected.

[0096] Depending on the material of the structure being inspected, different wavelengths may provide the desired level of penetration into lower layers. For distinguishing between minimum device features and defects within them, shorter wavelengths may be preferred. For example, one or more wavelengths in the range of 0.01 to 20 nm, or optionally 1 to 10 nm, or optionally 10 to 20 nm, may be selected. When reflecting materials of interest in semiconductor manufacturing, wavelengths shorter than 5 nm may be affected by very low critical angles. Therefore, selecting wavelengths greater than 5 nm can provide a stronger signal at higher incident angles. On the other hand, if the inspection task is to detect the presence of a certain material, such as to detect contamination, then wavelengths up to 50 nm may be useful.

[0097] A filtered beam 342 can enter the inspection chamber 350 from the radiation source 310, through which a substrate W containing the structure of interest is held by a substrate support 316 for inspection at a measurement location. The structure of interest is designated T. Optionally, the atmosphere within the inspection chamber 350 can be maintained near a vacuum by a vacuum pump 352, allowing SXR and / or EUV radiation to pass through the atmosphere without excessive attenuation. The irradiation system 312 has the function of focusing the radiation into a focused beam 356 and may include, for example, two-dimensional curved mirrors or a series of one-dimensional curved mirrors, as described in published U.S. Patent Application US2017 / 0184981A1 (the contents of which are incorporated herein by reference in their entirety), as mentioned above. When projected onto the structure of interest, focusing is performed to achieve a circular or elliptical spot S with a diameter less than 10 μm. The substrate support 316 includes, for example, an XY translation platform and a rotation platform, through which any portion of the substrate W can be brought to the focal point of the beam to be in the desired orientation. Thus, the radiation spot S is formed on the structure of interest. Alternatively or additionally, the substrate support 316 may include, for example, a tilting platform that can tilt the substrate W at an angle to control the incident angle of the focused beam on the structure of interest T.

[0098] Optionally, the illumination system 312 provides a reference radiation beam to a reference detector 314, which can be configured to measure the spectrum and / or intensity of different wavelengths in the filtered beam 342. The reference detector 314 can be configured to generate a signal 315, which is provided to the processor 320, and the filter can include information about the spectrum of the filtered beam 342 and / or the intensity of different wavelengths in the filtered beam.

[0099] The reflected radiation 360 is captured by detector 318, and the spectrum is provided to processor 320 for calculating the properties of the target structure T. The irradiation system 312 and detection system 318 thus form an inspection apparatus. This inspection apparatus may include hard X-ray, soft X-ray, and / or EUV spectroreflectometers of the types described in US2016282282A1, the contents of which are incorporated herein by reference in their entirety.

[0100] If the target Ta has a certain periodicity, the radiation from the focused beam 356 may also be partially diffracted. The diffracted radiation 397 follows another path at an angle well-defined relative to the angle of incidence, followed by reflected radiation 360. Figure 6 In the diagram, the diffraction radiation 397 is drawn schematically, and the diffraction radiation 397 may follow many other paths besides the drawn one. The inspection device 302 may also include another detection system 398 that detects and / or images at least a portion of the diffraction radiation 397. Figure 6 In this diagram, a single detection system 398 is depicted; however, embodiments of the inspection apparatus 302 may also include more than one detection system 398, arranged at different locations to detect and / or image diffracted radiation 397 in multiple diffraction directions. In other words, the (higher) diffraction order of the focused radiation beam striking the target Ta is detected and / or imaged by one or more detection systems 398. One or more detection systems 398 generate signals 399 that are provided to the measurement processor 320. Signal 399 may include information about the diffracted light 397 and / or may include an image obtained from the diffracted light 397.

[0101] To assist in the alignment and focusing of the light spot S with the desired product structure, the inspection apparatus 302 can also use auxiliary radiation to provide auxiliary optics under the control of the measurement processor 320. The measurement processor 320 can also communicate with a position controller 372 that operates a translation platform, a rotation platform, and / or a tilt platform. The processor 320 receives highly accurate feedback regarding the position and orientation of the substrate via sensors. The sensor 374 may include, for example, an interferometer, which can provide accuracy in the picometer region. During the operation of the inspection apparatus 302, spectral data 382 captured by the detection system 318 is delivered to the measurement processing unit 320.

[0102] As mentioned, alternative forms of inspection apparatus use hard X-rays, soft X-rays, and / or EUV radiation, optionally incident normally or near-normally, for example, to perform diffraction-based asymmetry measurements. Another alternative form of inspection apparatus uses hard X-rays, soft X-rays, and / or EUV radiation oriented at an angle greater than 1° or 2° to the direction parallel to the substrate. Both types of inspection apparatus can be provided in hybrid metrology systems. Performance parameters to be measured may include overlay (OVL), critical dimension (CD), focus of the lithography apparatus when printing the target structure on the lithography device, coherent diffraction imaging (CDI), and resolution overlay (ARO) measurements. Hard X-rays, soft X-rays, and / or EUV radiation may, for example, have wavelengths less than 100 nm, such as radiation in the range of 5 to 30 nm, optionally in the range of 10 to 20 nm. The radiation may be narrowband or broadband in nature. The radiation may have discrete peaks in a specific wavelength band or may have a more continuous nature.

[0103] Similar to optical scattering instruments used in modern manufacturing facilities, inspection device 302 can be used to measure structures within resist materials processed within a lithography unit (after development inspection or ADI), and / or to measure structures formed under harder materials (after etching inspection or AEI). For example, a substrate can be inspected using inspection device 302 after it has been processed by a development unit, etching unit, annealing unit, and / or other unit.

[0104] Measurement instruments (MTs) (including, but not limited to, the scatterers mentioned above) can perform measurements using radiation from a radiation source. The radiation used by the measurement instrument MT can be electromagnetic radiation. The radiation can be optical radiation, such as radiation in the infrared, visible, and / or ultraviolet portions of the electromagnetic spectrum. The measurement instrument MT can use radiation to measure or inspect the properties and various aspects of a substrate, such as a photolithographic pattern on a semiconductor substrate. The type and quality of the measurement may depend on several properties of the radiation used by the measurement instrument MT. For example, the resolution of an electromagnetic measurement may depend on the wavelength of the radiation; shorter wavelengths can measure smaller features, for example, due to diffraction limits. To measure features with small dimensions, it may be preferable to use radiation with short wavelengths, such as EUV, hard X-rays (HXR), and / or soft X-rays (SXR). To perform measurements at a specific wavelength or wavelength range, the measurement instrument MT needs access to a source that provides that / those wavelengths(s). Different types of sources exist for providing radiation at different wavelengths. Depending on the wavelength(s)(s) provided by the source, different types of radiation generation methods can be used. For extreme ultraviolet (EUV) radiation (e.g., 1 nm to 100 nm) and / or soft X-ray (SXR) radiation (e.g., 0.1 nm to 10 nm), the source can be an HHG or any other type of source mentioned above to obtain radiation at (multiple) desired wavelengths.

[0105] Figure 7 A simplified schematic diagram of embodiment 600 of the irradiation source 310 is shown, which can be an irradiation source for HHG. Relative to Figure 6 One or more features of the irradiation source in the described measurement tool may also suitably be present in the irradiation source 600. The irradiation source 600 includes a chamber 601 and is configured to receive pump radiation 611 having a propagation direction indicated by the arrow. The pump radiation 611 shown here is an example of pump radiation 340 from pump radiation source 330, such as... Figure 6 As shown. Pump radiation 611 can be directed into chamber 601 via radiation input 605, which can be an observation port and optionally made of fused silica or a similar material. Pump radiation 611 can have a Gaussian or hollow (e.g., annular) cross-sectional profile and can be incident (optionally focused) onto a gas flow 615 within chamber 601, the gas flow 615 having a flow direction indicated by a second arrow. Gas flow 615 comprises a small volume of a specific gas (e.g., air, neon (Ne), helium (He), nitrogen (N2), oxygen (O2), argon (Ar), krypton (Kr), xenon (Xe), carbon dioxide, and combinations thereof), referred to as a gas volume or gas target (e.g., a few cubic millimeters), where the gas pressure is above a specific value. Gas flow 615 can be a steady flow. Other media can also be used, such as metallic plasma (e.g., aluminum plasma).

[0106] The gas delivery system of the irradiation source 600 is configured to provide an airflow 615. The irradiation source 600 is configured to provide pump radiation 611 in the airflow 615 to drive the generation of emitted radiation 613. The region in which at least most of the emitted radiation 613 is generated is referred to as the interaction region. The interaction region can range from tens of micrometers (for tightly focused pump radiation) to several millimeters or centimeters (for moderately focused pump radiation) or even up to several meters (for very loosely focused pump radiation). The gas delivery system is configured to provide a gas target to generate emitted radiation at the interaction region of the gas target, and optionally, the irradiation source is configured to receive the pump radiation and provide the pump radiation at the interaction region. Optionally, the airflow 615 is provided by the gas delivery system to an emptied or nearly emptied space. The gas delivery system may include a gas nozzle 609, such as... Figure 6 As shown, it includes an opening 617 located in the outlet plane of the gas nozzle 609. Gas flow 615 is supplied from the opening 617. A gas trap is used to confine the gas flow 615 within a volume by extracting residual gas flow and maintaining a vacuum or near-vacuum atmosphere within the chamber 601. Optionally, the gas nozzle 609 may be made of a thick-walled tube and / or a material with high thermal conductivity to avoid thermal deformation due to high-power pump radiation 611.

[0107] It is conceivable that the dimensions of the gas nozzle 609 could also be used for scaled-up or scaled-down versions, ranging from micrometer-scale nozzles to meter-scale nozzles. This wide range of dimensional determinations stems from the fact that the setup can be scaled so that the pump radiation intensity at the gas flow ultimately reaches a specific range, which may be beneficial to the emitted radiation. This requires different dimensional determinations for different pump radiation energies, which can be pulsed lasers and pulse energies can range from tens of microjoules to joules. Optionally, the gas nozzle 609 has thicker walls to reduce nozzle deformation caused by thermal expansion effects, which can be detected, for example, by a camera. A gas nozzle with thicker walls can produce a stable gas volume with reduced variation. Optionally, the irradiation source includes a gas trap near the gas nozzle to maintain the pressure in chamber 601.

[0108] Due to the interaction between the pump radiation 611 and the gas atoms of the gas flow 615, the gas flow 615 converts a portion of the pump radiation 611 into emitted radiation 613, which can be Figure 6An example of emitted radiation 342 is shown. The central axis of emitted radiation 613 may be collinear with the central axis of incident pump radiation 611. Emitted radiation 613 may have a wavelength in the X-ray or EUV range, wherein the wavelength is in the range of 0.01 nm to 100 nm, optionally from 0.1 nm to 100 nm, optionally from 1 nm to 100 nm, optionally from 1 nm to 50 nm, or optionally from 10 nm to 20 nm.

[0109] In operation, the emitted radiation beam 613 can pass through the radiation output 607, and can subsequently be... Figure 6 The example of the illumination system 312 in the image shows that the illumination system 603 is manipulated and guided to the substrate to be inspected for measurement. The emitted radiation 613 can be directed (optionally focused) onto the structure on the substrate.

[0110] Because air (in fact, any gas) absorbs a large amount of SXR or EUV radiation, the volume between the airflow 615 and the wafer to be inspected may be emptied or nearly emptied. Since the central axis of the emitted radiation 613 may be collinear with the central axis of the incident pump radiation 611, the pump radiation 611 may need to be blocked to prevent it from passing through the radiation output 607 and entering the irradiation system 603. This can be achieved by... Figure 6 The filtering device 344 shown is incorporated into the radiation output 607, which is positioned in the path of the emitted beam and is opaque or nearly opaque to the pump radiation (e.g., opaque or nearly opaque to infrared or visible light), but at least partially transparent to the emitted radiation beam. The filter can be made of zirconium or a combination of multiple materials in multiple layers. When the pump radiation 611 has a hollow (optionally annular) cross-sectional profile, the filter can be a hollow (optionally annular) block. Optionally, the filter is neither perpendicular nor parallel to the propagation direction of the emitted radiation beam to achieve efficient pump radiation filtering. Optionally, the filtering device 344 includes a hollow block and a thin-film filter, such as an aluminum (Al) or zirconium (Zr) thin-film filter. Optionally, the filtering device 344 may also include a mirror that efficiently reflects the emitted radiation but poorly reflects the pump radiation, or a wire mesh that efficiently transmits the emitted radiation but poorly transmits the pump radiation.

[0111] This document describes methods, apparatus, and components for obtaining radiation emitted optionally at the high harmonic frequency of the pump radiation. The radiation generated by this process (optionally, using nonlinear effects to generate the HHG of the radiation at the harmonic frequency of the provided pump radiation) can be provided as radiation in a metrology tool (MT) for substrate inspection and / or measurement. If the pump radiation consists of short pulses (i.e., several cycles), the generated radiation is not necessarily exactly at the harmonic of the pump radiation frequency. The substrate can be a photolithographically patterned substrate. The radiation obtained by this process can also be provided in a photolithography apparatus (LA) and / or a photolithography cell (LC). The pump radiation can be pulsed radiation, which can provide a high peak intensity for a short burst.

[0112] Pump radiation 611 may include one or more wavelengths higher than one or more wavelengths of emitted radiation. Pump radiation may include infrared radiation. Pump radiation may include (multiple) wavelengths in the range of 500 nm to 1500 nm. Pump radiation may include (multiple) wavelengths in the range of 800 nm to 1300 nm. Pump radiation may include (multiple) wavelengths in the range of 900 nm to 1300 nm. Pump radiation may be pulsed radiation. Pulsed pump radiation may include pulses with a duration in the femtosecond range.

[0113] In some embodiments, the emitted radiation (optionally higher harmonic radiation) may include one or more harmonics of the pump radiation wavelength(s). The emitted radiation may include wavelengths in the extreme ultraviolet, soft X-ray, and / or hard X-ray portions of the electromagnetic spectrum. The emitted radiation 613 may include wavelengths in one or more of the following ranges: less than 1 nm, less than 0.1 nm, less than 0.01 nm, 0.01 nm to 100 nm, 0.1 nm to 100 nm, 0.1 nm to 50 nm, 1 nm to 50 nm, and 10 nm to 20 nm.

[0114] Radiation (such as the aforementioned higher harmonic radiation) can be provided as source radiation in a metrology tool (MT). The metrology tool (MT) can use the source radiation to perform measurements on a substrate exposed by a photolithography apparatus. The measurements can be used to determine one or more parameters of the structure on the substrate. Compared to using longer wavelengths (e.g., visible radiation, infrared radiation), using shorter wavelengths of radiation (e.g., EUV, SXR, and / or HXR wavelengths included in the aforementioned wavelength range) allows the metrology tool to resolve smaller features of the structure. Shorter wavelength radiation (such as EUV, SXR, and / or HXR radiation) can also penetrate deep into materials such as patterned substrates, meaning that deeper layers on the substrate can be measured. These deeper layers may not be reachable by longer wavelength radiation.

[0115] In a metrology tool (MT), source radiation can be emitted from a radiation source and directed onto a target structure (or other structure) on a substrate. Source radiation can include EUV, SXR, and / or HXR radiation. The target structure can reflect, transmit, and / or diffract the source radiation incident on it. The metrology tool (MT) can include one or more sensors for detecting diffracted radiation. For example, the metrology tool (MT) can include detectors for detecting the positive (+1) and negative (-1) first diffraction orders. The metrology tool (MT) can also measure specular reflection or transmission radiation (0th-order diffraction radiation). Other sensors for measurement can be present in the metrology tool (MT), for example, for measuring other diffraction orders (e.g., higher diffraction orders).

[0116] In example photolithography applications, an optical array, which can be referred to as an irradiator, can be used to focus the radiation generated by the HHG source onto a target on a substrate, transferring the radiation from the HHG source to the target. The HHG radiation can then be reflected from the target, detected, and processed, for example, to measure and / or infer the properties of the target.

[0117] Gas target HHG configurations can be broadly categorized into three separate types: gas jet, gas chamber, and gas capillary. Figure 7 An example gas jet configuration is depicted, in which a gas volume is introduced into a driving radiation laser beam. In the gas jet configuration, the interaction between the driving radiation and the solid portion is kept to a minimum. The gas volume may, for example, comprise a gas flow perpendicular to the driving radiation beam, and the gas volume is enclosed within a gas chamber. In a gas capillary arrangement, the dimensions of the capillary structure containing the gas are very small in the transverse direction, causing it to significantly affect the propagation of the driving radiation laser beam. The capillary structure may, for example, be a hollow-core optical fiber, where the hollow core is configured to contain the gas.

[0118] The gas jet HHG configuration offers relative degrees of freedom for shaping the spatial profile of the driving radiation beam in the far field, as it is not constrained by the limitations imposed by the gas capillary structure. The gas jet configuration may also have less stringent alignment tolerances. On the other hand, the gas capillary can provide an increased interaction zone between the driving radiation and the gaseous medium, which can optimize the HHG process.

[0119] For the use of HHG radiation, such as in measurement applications, it is separated from the driving radiation downstream of the gas target. The separation of HHG and driving radiation may differ for gas jet and gas capillary configurations. In both cases, driving radiation suppression schemes can include a metallic transmission filter to filter out any remaining driving radiation from the short-wavelength radiation. However, before such a filter can be used, the intensity of the driving radiation should be significantly reduced from its intensity at the gas target to avoid damaging the filter. Methods that can be used for this intensity reduction vary depending on the gas jet and capillary configuration. For gas jet HHG, due to the relative degrees of freedom in the shape and spatial profile (also referred to as spatial distribution and / or spatial frequency) of the driving radiation beam focused onto the gas target, this can be designed to result in low intensity in the far field along the direction of propagation of the short-wavelength radiation. This spatial separation in the far field means that an aperture can be used to block the driving radiation and reduce its intensity.

[0120] In contrast, in gas capillary structures, the spatial profile of the beam as it passes through the gaseous medium can be largely determined by the capillary. The spatial profile of the driving radiation can be determined by the shape and material of the capillary structure. For example, when hollow-core fiber is used as the capillary structure, the shape and material of the fiber structure determine which driving radiation modes are supported to propagate through the fiber. For most standard fibers, the supported propagation modes result in a spatial profile where high-intensity driving radiation overlaps with high-intensity HHG radiation. For example, the driving radiation intensity can be centered on a Gaussian or near-Gaussian profile in the far field.

[0121] While HHG is specifically referenced, it is understood that this invention can be practiced with all radiation sources, where the context permits. In one embodiment, the radiation source is the aforementioned laser-generated plasma (LPP) source for generating hard X-rays, soft X-rays, EUV, DUV, and visible radiation. In another embodiment, the radiation source is one of a liquid metal jet source, an inverse Compton scattering (ICS) source, a plasma channel source, a magnetic undulator source, a free electron laser (FEL) source, a compact storage ring source, a discharge-generated plasma source, a rotating anode source, a solid anode source, a particle accelerator source, and a microfocus source.

[0122] Photolithography apparatuses, along with associated measurement and inspection apparatuses, perform their patterning and / or measurement tasks under vacuum conditions. Even under vacuum conditions, non-negligible contaminants may be present within the chamber where patterning / measurement is performed. This chamber may be referred to as a container. Contaminants may deposit on the surfaces of components within the container, particularly in areas where high-intensity radiation is present. High-intensity radiation (especially high-intensity short-wavelength radiation) may interact with contaminants such as hydrocarbons and / or water, causing them to deposit on the surfaces of optical components. This can significantly affect the performance of these components and / or shorten their lifespan.

[0123] Existing techniques for keeping components such as optical parts clean involve using purge gases. However, purge gases can require large flow rates, which can be expensive and place a significant load on the vacuum pump. Therefore, such setups may require larger and more expensive vacuum pumps. One workaround is to place the optical components to be kept clean inside a flushing chamber. The flushing chamber may be a housing with narrow inlet and outlet channels. Significant gas densities and flow rates can be generated within these channels. Using such a flushing chamber can reduce gas consumption by one or more orders of magnitude.

[0124] Using a well-designed flushing chamber, the partial pressure of contaminants such as hydrocarbons within the flushing chamber can be several orders of magnitude lower than the partial pressure throughout the vacuum container. However, it is difficult to design a flushing chamber around all components, for example, due to space constraints and / or the potential need to actuate optical components. Actuators can be sources of contaminants and should not be placed in the flushing chamber, while optical components moved by actuators should be. Other challenges with flushing chambers may include making it more difficult to replace components contained within them, which may be required for maintenance. Flushing chambers can also add further complexity to an already complex setup.

[0125] Another challenge associated with using purge gases is that some of the most well-known self-cleaning purge gases, such as hydrogen, can add additional system complexity and material requirements to the overall system. This may be necessary to prevent the purge gas from unnecessarily etching surfaces inside the container. Hydrogen can be too reactive, and elements such as silicon, tin, zinc, and magnesium may pose a risk of etching and / or oxidation. If this occurs, these elements can form additional contaminants inside the container. The purity of the purge gas may also be low, and it may itself contain contaminants such as water. Therefore, the purge gas itself may introduce additional contaminants into the flushing chamber, which could shorten the lifespan of optical components. Cleaning mirrors can be difficult and an impactful process. Due to these challenges, preventing surface contamination inside the container is preferable to cleaning the surface.

[0126] This paper proposes an alternative to using purge gases such as hydrogen, employing cryogenics. Cryochemistry can be used to freeze hydrocarbons, water, and / or other contaminants at low temperatures, preventing their escape. All hydrocarbons that remain on the surface for a relatively long time at the operating temperature of the device / container can be considered contaminants to be removed. This is likely because these hydrocarbons may break down upon exposure to short-wavelength radiation and may leave carbon deposits on the surface of the optical components they reside on. Lighter hydrocarbons (e.g., methane, ethane, and in some instances propane, butane, or generally hydrocarbons with a mass less than 60 Daltons) are likely to be more volatile and therefore less likely to remain on the surface of the optical components for extended periods. Therefore, they can be removed more easily using a turbovacuum system, and carbon deposits are less likely to form on the surface. The operating temperature of the container can be essentially room temperature, for example, in the range of 5°C to 30°C.

[0127] Figure 8 A schematic representation of a component 800, which may be provided in a photolithography apparatus and / or a measurement apparatus, is depicted. The component includes a container 802 configured to receive a radiation beam 804. Component 800 also includes an internal structure 806, which may form part of the container or may be enclosed within the container. Component 800 also includes a temperature control system 808 configured to control the temperature of the internal structure 806 within a range of 77 K to 140 K. The cooling surfaces(s) of the internal structure may be referred to as (a)(a)(a)(a)(b))(c)(d). Component 800 may also include one or more optical components 810(a), 810(b), 810(c), 801(d) configured to guide radiation within the container 802. During component operation, the container may be placed under a vacuum. Component 800 may also include a radiation input 812 and a radiation output 814 for providing radiation to the interior and exterior of the container 802, respectively. Figure 8 The optical components 810(a) to 801(d) depicted are provided as examples only, and other component configurations may be provided.

[0128] Figure 8 An advantage of the depicted component 800 may be that it can provide cryogenic cooling within a container where high-intensity radiation may be present and where there is interaction with optical components. The presence of cold surfaces within the container means that contaminants may be adsorbed onto the surfaces. The colder the surface, the more difficult it may be for adsorbed contaminants to escape. A cooled internal structure can replace a purging airflow without introducing any of the challenges and difficulties associated with airflow. The internal structure can be configured to capture contaminants on at least one surface of the internal structure in order to remove them from the container. Contaminants may include hydrocarbons and / or water.

[0129] Low temperatures can cause contaminants to remain on cold surfaces exponentially longer. This can be understood using Arrhenius's law: τ = τ₀exp(E a / (kT)). In this equation, τ can be the dwell time, τ0 (~10 -13 s) could be the frequency of escape attempts, E a This can be the binding energy, T can be the temperature, and k can be the Boltzmann constant. At sufficiently low temperatures, adsorbed species may hardly leave the surface again. Alternatively, the vapor pressure of a contaminant at low temperatures may become so low that the contaminant source freezes and no longer enters a vacuum. For example, at 77 K, the vapor pressure of water may be less than 10. -12 At millibars, all hydrocarbons are likely to be solids, and only the lightest hydrocarbon (methane CH4) may have some remaining vapor pressure.

[0130] One or more optical components 810(a), 810(b), 810(c), 801(d) may be present within the container. The one or more optical components within the container may be configured to interact (e.g., guide or direct) with one or more types of radiation in the wavelength range of 1 nm to 20 nm. Due to the localized presence of shortwave radiation, the radiation may be incident on the components, making them susceptible to contaminants. The optical components may, for example, include reflective optics. Guiding a radiation beam through the optical components may include reflected or diffracted radiation beams. In some instances, the optical components may include transmissive optics. The optical components may, for example, include (ring) mirrors, filters, gratings, etc. The optical components may receive radiation entering the container at its input end and may direct at least a portion of the radiation toward the output end of the container.

[0131] Radiation that can propagate through a container may include short-wavelength radiation. The radiation beam may include multiple wavelengths. The radiation beam may include one or more wavelengths in, for example, the range of 1 nm to 20 nm, 1 nm to 10 nm, 10 nm to 20 nm, or 9 nm to 18 nm. The radiation may, for example, include wavelengths of (approximately) 13.5 nm. This short-wavelength radiation may be present at high intensity in localized areas. Due to the high energy associated with short-wavelength radiation, its effect on particles (such as contaminants) present in a vacuum and / or on the surfaces of optical components (such as mirrors) can be significant. Therefore, contaminant removal may be particularly important in settings using short-wavelength radiation.

[0132] The internal structure temperature can range from 77 K to 140 K. In some instances, the internal structure temperature can range from 90 K to 140 K, 90 K to 130 K, and 100 K to 125 K. In some examples, the internal structure temperature can be essentially 100 K, or approximately 100 K. An advantage of this temperature range is that it freezes contaminants such as (less volatile) hydrocarbons and water. An advantage of using a 100 K cooling temperature is that hydrogen may still be a gas at that temperature. Therefore, this temperature can be applied to settings using hydrogen. Oxygen may still be a gas around 90 K, and helium can remain gaseous up to 4 K. A temperature of 77 K might be interesting because it is easily achieved through cooling with liquid nitrogen. An example of introducing hydrogen might be in areas where carbon deposits are present. Hydrogen may interact with carbon from methane (CH4), which is likely volatile and can therefore be removed by a vacuum pump. Thus, hydrogen can reduce the amount of carbon deposits.

[0133] During operation, container 802 can be maintained at a vacuum pressure of 0.05 mbar or lower. In some instances, the container can be maintained at a vacuum pressure of 0.01 mbar or lower during operation. An advantage of a pressure of 0.05 mbar or lower is that the insulation provided by the vacuum is good enough that the temperature of the internal structure 806 is not conducted to the entire volume of container 802. Insulation of the cooled internal structure to its environment is important, for example, to prevent low temperatures from damaging surrounding components and / or the container. The lower the pressure, the better the insulation achieved by the vacuum. Another advantage of operating in a vacuum may be that it prevents light absorption.

[0134] In some implementations, the internal structure can be targeted at one or more specific components of interest. Figure 9 A graphical representation of component 900 is depicted, wherein a component 908 (e.g., an optical component) to be protected is at least partially enclosed by an internal structure 906. The internal structure may be referred to as housing 906. Housing 906 may include walls and an internal space formed by walls surrounding the internal space of housing 906. This may be an example of a component where the purge airflow is replaced by a cold housing surrounding the component to be protected. The optical component 908 and housing 906 may be provided within a container 902, for example, as described above. Figure 8 Described. The housing 906 may include an input and an output, through which radiation can enter and exit the housing via optical components 908. The cold housing 906 can be used as a cryogenic cooler, which may be referred to as a cold finger. The cryogenic cooler can trap contaminants such as hydrocarbons and water on its surface to a low temperature. In some embodiments, the housing 906 may be a container, which may optionally have the shape of a bucket, bottle, jug, cup, or bowl.

[0135] Input end 916 may include an elongated structure with a hollow core. Input end 916 may be oriented such that radiation incident on optical component 908 can propagate through the hollow core of the elongated structure of input end 916. Output end 918 may include an elongated structure with a hollow core. Output end 918 may be oriented such that radiation reflected / diffracted / transmitted by optical component 908 can propagate through the hollow core of the elongated structure of output end 918. The inner walls surrounding the hollow core of the input end and / or output end may be cooled such that any contaminants attempting to enter the interior space of housing 906 via the input end or output end are adsorbed onto the walls of the housing. Therefore, the elongated design of the input / output end of the housing may have the advantage of trapping contaminants attempting to enter the interior space of the housing. As a result, the contaminant concentration in the interior space may be lower than the overall contaminant concentration within container 902. This results in increased protection against contaminant deposition for optical component 908. Contaminants present in the interior space of the housing may also be adsorbed onto the inner wall surface of the housing. In some embodiments, optical component 908 present within the housing may be heated. The surface of an optical element can be heated to stimulate the desorption of contaminants from the heated surface. A heated surface could be, for example, the reflective surface of a mirror. Heating the surface of an optical element also prevents it from cooling down, thus avoiding it becoming a low-temperature surface despite the presence of a cold environment / casing.

[0136] More generally, the geometry of the enclosure may resemble that of a conventional flushing chamber, with narrow inlet and outlet channels forming the inlet and outlet ends. Due to the low temperature, hydrocarbon or water contaminants attempting to enter the flushing chamber will adhere to the walls. This significantly reduces the likelihood of contaminants entering the interior space of the enclosure through the narrow channels at the ends. The geometry requirements for the enclosure may not be as stringent as for a conventional flushing chamber. Where a conventional flushing chamber requires (close to) a leak-proof structure, the requirements for a cooling enclosure are less stringent. The cold enclosure may only cover the line of sight of the sensitive surface of the optical component 908. Even if the enclosure is not leak-proof, contaminants may still interact with the cold surfaces of the enclosure before they can reach the optical component 908. Furthermore, any contaminants that do not adhere to the cold surfaces of the enclosure 906 may be sufficiently volatile for a vacuum pump to pump them out of container 902.

[0137] In another embodiment, the aforementioned rinsing chamber uses helium as the rinsing gas. Using helium as the rinsing gas in a vacuum chamber to clean mirrors offers several benefits, including chemical inertness, high fluidity, efficient heat transfer, low viscosity, minimal contamination, and vacuum compatibility. These properties make helium ideal for effectively and safely cleaning mirrors without damaging their surfaces or impairing their optical performance. Optionally, the rinsing gas can be recycled.

[0138] For example, an assembly with a cryogenic cooling housing surrounding optical components can be used in a measurement or inspection apparatus. The measurement apparatus, for example, can use short-wavelength radiation to measure one or more parameters of a target substrate, such as a photolithographically patterned target substrate. The pressure within the measurement apparatus can be 0.05 mbar or lower, such as, for example, 0.01 mbar or lower. The temperature control system for the cooling housing can be, for example, a liquid nitrogen cooling system.

[0139] Another example implementation where contaminant removal might be of interest is in lithography, metrology, or inspection apparatus. During the operation of a lithography tool, the presence of contaminants must be sufficiently low to ensure proper operation. The first potential contaminant is the presence of water. After the system is vented (which may turn it up to atmospheric pressure), the walls and components inside the lithography tool container may be covered with water. This water can pose a risk to the components inside the container, for example, due to oxidation. The water should be removed before turning on the radiation source (e.g., an EUV / SXR radiation source). However, removing water contaminants can be slow and can take several hours, representing a significant downtime that reduces the usability of the lithography tool to the user. Reducing the downtime is desirable. Turning on the radiation source too early before removing contaminants can adversely affect the lifespan of optical components, such as through mirror degradation.

[0140] This paper proposes a method for accelerating descent using a cryogenically cooled internal structure. Contaminant removal from the cryogenically cooled surfaces can facilitate pressure reduction within the vessel. This cryogenically cooled descent can be performed in parallel with a turbomolecular vacuum pumping system. The advantages of activating the cryogenic cooling during the descent process may include reduced downtime and increased tool availability. The cryogenically cooled internal structure should not be activated until the pressure within the vessel is sufficiently low to achieve insulation. For example, insulation can be achieved at pressures of 0.05 mbar or higher. In some instances, this pressure level may be referred to as the pre-vacuum level. The cryogenically cooled internal structure could be, for example, […]. Figure 8 The internal structure 806 shown and the features described regarding component 800.

[0141] In the example implementation, the internal structure 806 can form part of the container 802. For example, the internal structure 806 can form part of the inner wall of the container 802. An advantage of this location for the internal structure 806 is that it does not occupy additional space within the container. The container 802 may be crammed with components and free space required for radiation propagation paths, meaning that limited space can be used to add internal cooling structures. The shape of the internal structure forming part of the container's inner wall can be flat or curved. The connection between the cryogenic cooling internal structure and the rest of the container should be made of a material with poor thermal conductivity to avoid transferring cooling functionality to other parts of the container.

[0142] While the introduction of a cryogenic cooling internal structure may help accelerate the pumping process and aid in the removal of water contaminants, its presence can have drawbacks. Water and other contaminants may be trapped on the surfaces of the internal structure, but they are not actually removed from the container. During operation, radiation or plasma effects present in the device may cause desorption, which could compromise the vacuum quality during tool operation. The available surface area may be limited and may not be located near the optical components(s) most in need of protection.

[0143] To address these issues, an internal structure 806 can be provided, which is enclosed within a container 802 and is movable, such as retractable, both inside and outside the container 802. For example, the movable internal structure can be configured to insert into an optical compartment within the container, which may include portions within the container volume that are retained as a propagation path for radiation when the radiation beam is off during container descent. The movable internal structure can be configured to retract from the propagation path after low pressure is reached and contaminants have been removed, and before the radiation beam is turned on.

[0144] In some implementations, the movable internal structure can be moved to different locations within the container after descent. One advantage of placing the internal structure in the radiation path during descent is that the cryogenic cooling surface is closer to optical components to be protected from contaminants. Another advantage of moving the cryogenic cooling surface is increasing the distance between the cryogenic cooling structure and radiation and / or the radiation-generated plasma. This can mitigate the risk of contaminant desorption during tooling operation, which can be caused by the presence of high-energy radiation / plasma particles.

[0145] In some implementations, the movable internal structure can be moved to a location outside the container after evacuation. This location outside the container could be, for example, a vacuum chamber separate from the container, such as one adjacent to it. The separate vacuum chamber can be completely closed off from the main container. This can facilitate the complete removal of contaminants from the container before radiation is initiated. This may eliminate the risk of contaminant desorption during operation. The separate vacuum chamber can be opened independently of the container. Therefore, the internal structure can be heated to release contaminants from its surface, which can then be evacuated by the separate chamber's vacuum system without requiring downtime for the lithography tool.

[0146] Another advantage of providing a movable internal structure may be the ability to offer a larger cryogenic cooling surface area. This could increase the rate at which contaminants are captured by the surface of the internal structure, thereby improving the efficiency of the pumping process. The movable internal structure can also utilize the container volume reserved for radiation.

[0147] An internal structure 806 can be provided that exists within the container but does not form part of the container's inner wall. Compared to an internal structure that forms part of the container's inner wall, the two sides of the panel surface inserted into the container can be used for contaminant adsorption. Technical solutions that increase the effective surface area of ​​the cryogenically cooled internal structure can be considered. For example, the internal structure may include multiple insertable rods. This may increase the amount of available surface area that can trap contaminants. The internal structure may include an extendable body for increasing the surface area of ​​the internal structure during descent. The extendable body may, for example, include bellows and / or folded surfaces. This can further increase the effective contaminant trapping area while reducing the volume required to install the internal structure.

[0148] Another advantage of making the internal structure movable is that contaminants can accumulate on the cryogenic cooling surfaces if they operate for extended periods, potentially requiring cleaning. While such cleaning can be performed during maintenance, this can result in additional downtime. Therefore, an alternative approach is to make the cryogenic cooling inner surfaces retractable. For example, the internal structure could be retractable while the device is running. In some instances, the internal structure may retract once descent is complete, but before the radiation source is turned on.

[0149] The temperature control system 808 may include a motor for powering the cooling device. Even with high insulation achieved under high vacuum conditions, the cooling load within the vacuum chamber may be non-zero. Radiative heat transfer may occur from the surfaces of the internal structure to the inner walls of the container and optical components within the container. The walls and optical components may be at approximately room temperature. Convective heat transfer may also occur, for example, due to gas flows (e.g., hydrogen flow) present in the device.

[0150] For example, the motor can be included in the refrigerator, and the motor can be connected to a liquid nitrogen tank. The motor used to power the cooling system can be decoupled from the container via a mechanical decoupling device. The mechanical decoupling device connects the cooling infrastructure outside the container to the internal structure located within the container without transmitting vibrations from the motor to the container. This means that the mechanical decoupling device can transfer the cooling effect to the interior of the container without connecting any vibrations associated with the motor to the container interior. The mechanical decoupling device can be a heat exchanger, which may, for example, include one or more copper braids.

[0151] For example, other types of cooling links can be considered, such as cryogenic cycles of liquid nitrogen. The advantage of such cryogenic cycles may be the rapid switching between cooling and heating. Other types of cooling include cryogenic heat exchangers and two-phase cooling (e.g., liquid nitrogen balanced with gaseous nitrogen N2). Combinations of two or more cooling systems can also be implemented.

[0152] In some example implementations, the temperature of a component protected from contaminants can be heated to a (slight) higher level relative to its surroundings. This reduces the residence time of contaminants on the component surface. The increased energy from the elevated temperature can further enhance the release of contaminants, such as hydrocarbons, thereby increasing the likelihood that unwanted contaminants will migrate from the component surface to the cooled inner surface for contaminant capture.

[0153] In some example implementations, the internal structure may include a textured surface. A textured surface can be achieved, for example, by adding nanoparticles or metallic aerogels. Other ways to introduce texture may include adding grooves, roughening the material, and / or adding a porous surface coating. Having a textured surface can increase the overall (cooled) surface area of ​​the internal structure, thereby increasing the amount of space available for adsorbing and trapping contaminants.

[0154] Another potential advantage of having a temperature-controlled internal structure within the container is that it provides some additional cooling effect by extracting heat introduced by radiation present in the container during operation.

[0155] Figure 10 Example graph 1000 depicts the vapor pressure p (mbar) of different gases as a function of temperature T (Kelvin). This graph can be based on the Clausius-Clapeyron relation. Line 1002 depicts hydrogen (H2), line 1004 depicts nitrogen (N2), line 1006 depicts oxygen (O2), line 1008 depicts methane (CH4), line 1010 depicts carbon dioxide (CO2), line 1012 depicts water (H2O), and line 1014 depicts dodecane (C6). 12 H 26 Line 1016 depicts liquid nitrogen, and line 1018 depicts boiling water. This graph shows that for shell cryogenic temperatures of 100 K or lower, the water equilibrium pressure will be much lower than 10 K. -10 Millibars. At temperatures of 100 K or near, hydrogen (H2), nitrogen (N2), and methane (CH4) will not be pumped. Methane gas (CH4) may be beneficial in some applications. Due to its volatility, it may be easier to remove using a turbomolecular vacuum system.

[0156] In some implementations, thermally controlled insulating elements, such as controlled insulating rings, can be added around the cryogenic cooling surfaces of the internal structure. This could be, for example, a temperature-controlled flow of water or a compensating heating element, or a combination of both. The insulating elements can be used to protect temperature-sensitive components, such as optical parts within a container, from the effects of the cryogenic cooling surfaces. For example, the component to be protected could be a mirror.

[0157] In some instances, the internal structure can be coated with a material that traps tin (Sn). This coating can, for example, include ruthenium.

[0158] One embodiment may include a computer program comprising one or more sequences of machine-readable instructions describing methods for optical lateral approaches and / or analyzing measurements to obtain information about a photolithography process. Another embodiment may include computer code comprising one or more sequences of machine-readable instructions or data describing the method. The computer program or code may be, for example... Figure 6 The unit MPU and / or Figure 3 The control unit CL executes the operation. A data storage medium (e.g., semiconductor memory, disk, or optical disc) containing such a computer program or code can also be provided. If existing measuring devices (e.g.) Figure 6 If the type shown is already in production and / or use, embodiments of the invention can be implemented by providing an updated computer program product for causing a processor to execute one or more methods described herein. The computer program or code may optionally be arranged to control optical systems, substrate supports, etc., to perform methods for measuring parameters of a photolithography process on suitable plurality of targets. The computer program or code may update the photolithography and / or measurement scheme to measure other substrates. The computer program or code may be arranged to (directly or indirectly) control a photolithography apparatus to pattern and process other substrates.

[0159] The irradiation source can be provided in, for example, a measurement device (MT), an inspection device, a lithography device (LA), and / or a lithography unit (LC).

[0160] The properties of the emitted radiation used to perform a measurement can affect the quality of the resulting measurement. For example, the shape and size of the transverse beam profile (cross-section) of the radiation beam, the intensity of the radiation, and the power spectral density of the radiation can all influence the measurement performed by the radiation. Therefore, it is beneficial to provide radiation from a source that has properties that lead to high-quality measurements.

[0161] Other embodiments are disclosed in the following numbered clauses: 1. A component comprising: The container is configured to receive the radiation beam; Internal structure, forming part of the container or enclosed within the container; The temperature control system is configured to keep the temperature of the internal structure within the range of 77 K to 140 K. 2. The component according to Clause 1, wherein the container is configured to be at a pressure of 0.05 mbar or less, or 0.01 mbar or less, during operation of the component. 3. The component according to any of the foregoing clauses, wherein the temperature control system is configured to control the temperature of the internal structure within a range of 90 K to 140 K, optionally within a range of 90 K to 130 K, optionally within a range of 100 K to 125 K, and optionally substantially 100 K. 4. The component according to any of the preceding clauses, wherein the radiation beam includes one or more wavelengths in the range of 1 nm to 20 nm, 1 nm to 10 nm, 10 nm to 20 nm, 9 nm to 18 nm, or 13.5 nm. 5. A component according to any of the foregoing clauses, wherein the internal structure is configured to capture contaminants on at least one surface of the internal structure. 6. Components according to Clause 5, wherein the internal structure is configured to remove captured contaminants from the container. 7. Components according to any one of Clauses 5 to 6, wherein the contaminants include hydrocarbons. 8. Components according to any one of Clauses 5 to 7, wherein the contaminant includes water. 9. The components according to any of the foregoing clauses also include optical components within the container. 10. The component according to Clause 9, wherein the optical component includes a reflective optical component, and wherein the radiation beam guided by the optical component includes a reflective radiation beam. 11. A component according to any one of Clauses 9 to 10, wherein the optical component is configured to guide one or more wavelengths of radiation in the range of 1 nm to 20 nm. 12. A component according to any of the foregoing clauses, wherein the internal structure is configured to be cooled during the process of depressurizing within the pumping vessel. 13. A component according to any of the foregoing clauses, wherein the internal structure includes a textured surface. 14. The component according to Clause 13, wherein the textured surface comprises at least one of nanoparticles or metallic aerogel. 15. A component according to any of the foregoing clauses, wherein the internal structure is enclosed within a container and is movable within the container. 16. Components according to Clause 15, wherein the internal structure is capable of moving into and out of the container. 17. A component according to any one of Clauses 15 to 16, wherein the movable internal structure is configured to insert into the propagation path of radiation during the descent of the container when the radiation beam is off, and is configured to retract from the propagation path before the radiation beam is turned on. 18. A component according to any one of Clauses 15 to 17, wherein the internal structure includes a plurality of insertable rods. 19. A component according to any one of clauses 15 to 17, wherein the internal structure includes an extendable body for increasing the surface area of ​​the internal structure. 20. A component according to any one of clauses 1 to 14, wherein the internal structure forms part of the container and forms part of the inner wall of the container. 21. The component according to any one of clauses 15 to 20, wherein the temperature control system includes a motor for supplying power to the cooling device, and wherein the motor is separated from the container by a mechanical decoupling device. 22. Components according to Clause 21, wherein the mechanical decoupler is a heat exchanger. 23. A component according to any one of clauses 21 to 22, wherein the motor is configured to drive the compressor pump. 24. A component according to any one of clauses 1 to 14, wherein the internal structure is an enclosure enclosing the internal space, the enclosure comprising: The input end is configured to be positioned in the propagation path of the radiation beam, so that the radiation beam is guided into the internal space of the housing; and The output end is configured to be positioned in the propagation path of the radiation beam, so that the radiation beam is guided out of the interior space of the housing. 25. The component according to Clause 24, wherein the input end includes an elongated structure comprising a hollow core arranged along the propagation path of the radiation beam, such that the radiation beam propagates along the hollow core of the elongated structure. 26. The component according to any one of clauses 24 to 25, wherein the output end includes an elongated structure comprising a hollow core arranged along the propagation path of the radiation beam, such that the radiation beam propagates along the hollow core of the elongated structure. 27. A component according to any one of clauses 24 to 26, wherein the housing is configured to capture contaminants on at least one surface adjacent to the interior space for removal from the interior space. 28. A component according to any one of Clauses 24 to 27, wherein the temperature control system includes a liquid nitrogen cooling system. 29. A measuring device comprising components according to any one of clauses 1 to 28. 30. An inspection device comprising a component according to any one of clauses 1 to 28. 31. An exposure apparatus comprising a component according to any one of clauses 1 to 28. 32. A photolithography apparatus comprising any of the components according to any one of clauses 1 to 28. 33. A photolithography unit comprising the means according to any one of clauses 29 to 32.

[0162] While this article provides specific references to the use of photolithography apparatuses in IC manufacturing, it should be understood that the photolithography apparatuses described herein can have other applications. Possible other applications include the fabrication of integrated optical systems, guiding and detecting patterns in magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, etc.

[0163] Although specific examples are referred to herein in the context of a lithography apparatus, these examples can be used in other apparatuses. Examples may form part of a mask inspection apparatus, a measurement apparatus, or any apparatus that measures or processes objects such as wafers (or other substrates) or masks (or other patterning equipment). These apparatuses are generally referred to as lithography tools. Such lithography tools may use vacuum conditions or ambient (non-vacuum) conditions.

[0164] Although specific references to embodiments may be made herein in the context of an inspection or measurement apparatus, embodiments can be used in other apparatuses. Embodiments may form part of a mask inspection apparatus, a lithography apparatus, or any apparatus for measuring or processing objects such as wafers (or other substrates) or masks (or other patterning equipment). The term “measurement apparatus” (or “inspection apparatus”) may also refer to an inspection apparatus or inspection system (e.g., a measurement apparatus or measurement system). For example, an inspection apparatus including embodiments may be used to detect defects in a substrate or defects in a structure on a substrate. In such embodiments, the characteristics of interest in the structure on the substrate may be related to defects in the structure, the absence of a specific portion of the structure, or the presence of an unwanted structure on the substrate.

[0165] Although the above may have specifically referenced the embodiments in the context of optical lithography, it is to be understood that the invention is not limited to optical lithography and can be used in other applications, such as imprint lithography, where the context permits.

[0166] While the targets or target structures described above (more generally, structures on a substrate) are measurement target structures specifically designed and formed for measurement purposes, in other embodiments, the properties of interest can be measured on one or more structures that are functional parts of a device formed on a substrate. Many devices have regular, grating-like structures. The terms structure, target grating, and target structure used herein do not require that the structure be specifically provided for the measurement being performed. Furthermore, the pitch of the measurement target may be close to or smaller than the resolution limit of the scatterer's optical system, but may be much larger than the size of a typical non-target structure (optionally a product structure) fabricated by photolithography in the target portion C. In practice, the lines and / or spaces of the overlaid grating within the target structure may include smaller structures with similar dimensions to the non-target structures.

[0167] Although specific embodiments have been described above, it should be understood that the invention can be practiced in ways other than those described. The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made to the described invention without departing from the scope of the claims set forth below.

[0168] Although the terms "measuring apparatus / tool / system" or "inspection apparatus / tool / system" are specifically used, these terms can refer to tools, apparatus, or systems of the same or similar type. For example, an inspection or measuring apparatus including embodiments of the present invention can be used to determine the characteristics of a structure on a substrate or wafer. For example, an inspection or measuring apparatus including embodiments of the present invention can be used to detect defects in a substrate or defects in a structure on a substrate or wafer. In such embodiments, the characteristics of interest in a structure on a substrate may be related to defects in the structure, the absence of a specific portion of the structure, or the presence of an unwanted structure on the substrate or wafer.

[0169] Although specific references are made to HXR, SXR, and EUV electromagnetic radiation, it is to be understood that the invention can be practiced with all electromagnetic radiation, including radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays, where the context permits.

[0170] Additional objects, advantages, and features of the invention are set forth in this specification and will become apparent in part to those skilled in the art upon review of the following, or may be learned by practicing the invention. The invention disclosed herein is not limited to any particular set or combination of objects, advantages, and features. Various combinations of the stated objects, advantages, and features are contemplated to constitute the invention disclosed herein.

Claims

1. A component comprising: The container is configured to receive the radiation beam; Internal structure, forming part of the container or enclosed within the container; A temperature control system is configured to maintain the temperature of the internal structure within the range of 77 K to 140 K.

2. The component of claim 1, wherein the container is configured to be at a pressure of 0.05 mbar or less, or 0.01 mbar or less, during operation of the component.

3. The component according to any one of the preceding claims, wherein the temperature control system is configured to control the temperature of the internal structure within a range of 90 K to 140 K, optionally within a range of 90 K to 130 K, optionally within a range of 100 K to 125 K, and optionally substantially 100 K.

4. The component according to any one of the preceding claims, wherein the internal structure is configured to capture contaminants on at least one surface of the internal structure.

5. The component according to any one of the preceding claims, further comprising an optical component within the container, wherein optionally the optical component includes a reflective optical component, and wherein optionally guiding the radiation beam through the optical component comprises: The radiation beam is reflected.

6. The component according to any one of the preceding claims, wherein the internal structure is configured to be cooled during the process of depressurizing the container.

7. The component according to any one of the preceding claims, wherein the internal structure includes a textured surface.

8. The component according to any one of the preceding claims, wherein the internal structure is enclosed within the container and is movable within the container.

9. The component of claim 8, wherein the internal structure is movable into and out of the container.

10. The component according to any one of claims 8 to 9, wherein the internal structure comprises: An extendable body is used to increase the surface area of ​​the internal structure.

11. The component according to any one of claims 1 to 7, wherein the internal structure forms part of the container and forms part of the inner wall of the container.

12. The component according to any one of claims 8 to 11, wherein the temperature control system comprises: An electric motor is used to power the cooling device, and the electric motor is separated from the container by a mechanical decoupling device.

13. The component according to any one of claims 1 to 7, wherein the internal structure is a shell enclosing an internal space, the shell comprising: The input end is configured to be positioned in the propagation path of the radiation beam, such that the radiation beam is guided into the interior space of the housing; as well as The output end is configured to be positioned in the propagation path of the radiation beam, such that the radiation beam is guided away from the interior space of the housing.

14. A measuring or inspection apparatus comprising the components according to any one of claims 1 to 13.

15. A photolithography apparatus comprising the components according to any one of claims 1 to 13.

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