Optical components based on hollow photonic crystal fibers for broadband radiation generation

Abstract

Optical components and methods of making the same are disclosed. A first optical component includes a hollow-core photonic crystal fiber including an inner capillary for guiding radiation and an outer capillary surrounding the inner capillary; and at least one output end section having an inner diameter that is greater over at least a portion of the output end section than an inner diameter of the outer capillary along a central portion of the hollow-core photonic crystal fiber preceding the output end section. A second optical component includes a hollow-core photonic crystal fiber and a ferrule arrangement.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to EP application 19204985.6, filed on August 24, 2019, and EP application 19217381.3, filed on December 18, 2019, which are incorporated herein by reference in their entirety. Technical Field

[0003] This invention relates to a broadband radiation generator based on hollow-core photonic crystal fiber, and more particularly to such a broadband radiation generator related to measurement applications in integrated circuit manufacturing. Background Technology

[0004] A lithography apparatus is a machine configured to apply a desired pattern onto a substrate. Lithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). For instance, a lithography apparatus can project a pattern (often referred to as a “design layout” or “design”) onto a radiation-sensitive material (resist) layer disposed on a substrate (e.g., a wafer) at a patterning apparatus (e.g., a mask).

[0005] To project patterns onto a substrate, photolithography equipment 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 equipment using radiation with a wavelength of, for example, 193 nm, photolithography equipment using extreme ultraviolet (EUV) radiation in the range of 4 to 20 nm (e.g., 6.7 nm or 13.5 nm) can be used to form smaller features on the substrate.

[0006] Low-k1 lithography can be used to process features with dimensions smaller than the traditional resolution limits of lithography equipment. 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 equipment, CD is the "critical size" (typically the smallest feature size to be printed, but in this case, half the 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 resemble the shape and size designed by the circuit designer in order to achieve specific electrical functionality and performance. To overcome these difficulties, complex fine-tuning steps can be applied to the lithography projection equipment and / or design layout. These include, for example, but not limited to, optimization of NA, custom illumination schemes, the use of phase-shifting patterning apparatus, various optimizations of the design layout (such as optical proximity correction (OPC, sometimes also called "optical and process correction") in the design layout), or other methods generally defined as "resolution enhancement techniques" (RET). Alternatively, tight control loops used to control the stability of the lithography equipment can be used to improve pattern reproduction at low k1.

[0007] Metrological tools are used in many aspects of IC manufacturing processes, such as alignment tools for properly positioning substrates before exposure, leveling tools for measuring the surface topology of substrates, and tools for, for example, focus-based control and scattering measurements, to inspect / measure exposed and / or etched products in process control. In each case, a radiation source is required. Broadband or white light radiation sources are increasingly used in these metrological applications for various reasons, including measurement robustness and accuracy. Improvements to existing devices for broadband radiation generation are desired. Summary of the Invention

[0008] In a first aspect of the invention, an optical component is provided, comprising: a hollow photonic crystal fiber including an inner capillary for guiding radiation and an outer capillary covering the inner capillary; and at least one output end section, the inner diameter of the at least one output end section over at least a portion of the output end section being greater than the inner diameter of the outer capillary along a central portion of the hollow photonic crystal fiber prior to the output end section.

[0009] In a second aspect of the invention, an optical component is provided, comprising a hollow-core photonic crystal fiber and a sleeve device, the sleeve device comprising at least one sleeve covering at least a corresponding end portion of each end of the hollow-core photonic crystal fiber; wherein: the internal capillaries of the hollow-core photonic crystal fiber are collapsed to define a tapered core region at each end of the hollow-core photonic crystal fiber, the tapered core region comprising a region in which the diameter of the hollow core of the hollow-core photonic crystal fiber increases toward each end of the hollow-core photonic crystal fiber; and a contact region wherein the sleeve device contacts the hollow-core photonic crystal fiber, the contact region being entirely located or extending beyond the tapered core region relative to the principal axis of the hollow-core photonic crystal fiber.

[0010] Other aspects of the invention include a broadband light source and a measuring device, and a method of manufacturing optical components of the first and second aspects, the broadband light source and the measuring device including the optical components of the first and second aspects. Attached Figure Description

[0011] Embodiments of the invention will now be described by way of example only with reference to the accompanying schematic diagrams, in which:

[0012] Figure 1 A schematic diagram of a photolithography device is depicted;

[0013] Figure 2 A schematic diagram of the photolithography unit is depicted;

[0014] Figure 3 A schematic representation of overall photolithography is depicted, illustrating the collaboration between three key technologies used to optimize semiconductor manufacturing;

[0015] Figure 4 A schematic diagram of a scattering measurement device used as a measurement apparatus is depicted, which may include a radiation source according to an embodiment of the present invention.

[0016] Figure 5 A schematic diagram of a horizontal sensor device that may include a radiation source according to embodiments of the present invention is depicted.

[0017] Figure 6 A schematic diagram of an alignment sensor device that may include a radiation source according to embodiments of the present invention is depicted.

[0018] Figure 7 Cross sections of several HC-PCF designs for supercontinuum generation are schematically depicted;

[0019] Figure 8 A broadband light source device based on inflatable HC-PCF in a known configuration is schematically depicted.

[0020] Figure 9A gas-filled HC-PCF bulb according to (a) the first embodiment and (b) the second embodiment is schematically depicted;

[0021] Figure 10 A mounting device that can be used to mount an optical device as disclosed herein is schematically depicted;

[0022] Figure 11 (a) to Figure 11 (c) Examples of optical components in three different configurations of the second embodiment are schematically depicted;

[0023] Figure 12 An enlarged end section of the HC-PCF according to an embodiment of the present invention is schematically depicted;

[0024] Figure 13 An alternative enlarged end segment of the HC-PCF according to an embodiment of the present invention is schematically depicted; and

[0025] Figure 14 (a) to Figure 14 (e) schematically describes the use of manufacturing such as Figure 12 and 13 The manufacturing method of HC-PCF is shown. Detailed Implementation

[0026] In this document, the terms “radiation” and “beam” are used to cover all types of electromagnetic radiation, including ultraviolet radiation (e.g., with wavelengths of 365, 248, 193, 157, or 126 nm) and EUV (extreme ultraviolet radiation, e.g., with wavelengths in the range of about 5–100 nm).

[0027] 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 incident radiation beam corresponding to a pattern to be created in a target portion of a substrate. The term "optical valve" may also be used in this context. Examples of such patterning apparatuses, besides classic masks (transmission or reflection, binary, phase-shifting, hybrid, etc.), include programmable mirror arrays and programmable LCD arrays.

[0028] Figure 1A lithography apparatus LA is schematically depicted. 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, or EUV radiation); a mask support (e.g., a mask stage) MT configured to support a pattern forming apparatus (e.g., a mask) MA and connected to a first positioner PM configured to precisely position the pattern forming 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 precisely 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 pattern forming apparatus MA onto a target portion C (e.g., comprising one or more dies) of the substrate W.

[0029] In operation, the irradiation system IL receives a radiation beam from the radiation source SO, for example, via a beam delivery system BD. The irradiation system IL may include various types of optical components, such as refractive, reflective, 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 can be used to adjust the radiation beam B to have a desired spatial and angular intensity distribution in its cross-section at the plane of the pattern forming apparatus MA.

[0030] The term "projection system" PS as used herein should be interpreted broadly to encompass all types of projection systems, including refractive, reflective, anti-refractive, distorting, magnetic, electromagnetic, and / or electrostatic optical systems, or any combination thereof, depending on the exposure radiation used, and / or other factors such as the use of immersion liquids or vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system" PS.

[0031] 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) having 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 techniques is given in US6952253, which is incorporated herein by reference.

[0032] The lithography equipment LA can also be of the type with two or more substrate supports WT (also known as "dual stage"). In such a "multi-stage" machine, the substrate supports WT can be used in parallel, and / or a preparation step for subsequent exposure of the substrate W can be performed on the substrate W located on one of the substrate supports WT, while another substrate W on another substrate support WT is used to expose a pattern on another substrate W.

[0033] In addition to the substrate support WT, the lithography apparatus LA may include a measurement stage. The measurement stage is arranged to hold sensors and / or cleaning devices. The sensors may be arranged to measure the properties of the projection system PS or the properties of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning devices may be configured to clean parts of the lithography apparatus, such as a portion of the projection system PS or a system providing immersion liquid. The measurement stage may be movable below the projection system PS as the substrate support WT moves away from the projection system PS.

[0034] In operation, a radiation beam B is incident on a pattern forming apparatus (e.g., a mask) MA held on a mask support T and patterned by a pattern (design layout) present on the pattern forming apparatus MA. After passing through the mask MA, the radiation beam B is projected by a projection system PS, which focuses the radiation beam onto a target portion C of the substrate W. With the aid of a second positioner PW and a position measurement system IF, the substrate support WT can be precisely moved, for example, to position different target portions C in the path of the radiation beam B at focused and aligned positions. Similarly, a first positioner PM and possibly another position sensor ( Figure 1 (Not explicitly shown) can be used to precisely position the pattern forming apparatus MA relative to the path of the radiation beam B. The pattern forming apparatus MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the substrate alignment marks P1, P2 occupy dedicated target portions, they can be located in the space between the target portions. When the substrate alignment marks P1, P2 are located between the target portions C, they are referred to as scribe-lane alignment marks.

[0035] like Figure 2 As shown, a lithography apparatus LA can form part of a lithography unit LC, sometimes referred to as a lithography unit or (lithography) cluster, which typically also includes equipment for performing pre- and post-exposure processing on a substrate W. Conventionally, these include a spin coater SC to deposit a resist layer, a developer DE to develop the exposed resist, a cooling plate CH, and a baking plate BK, for example, to regulate the temperature of the substrate W, and for example, to regulate the dissolution of the resist layer. A substrate processor or robot RO picks up the substrate W from input / output ports I / O1, I / O2, moves the substrate W between different processing devices, and transfers the substrate W to the loading chamber LB of the lithography apparatus LA. The devices in the lithography unit, often collectively referred to as tracks, are typically under the control of a track control unit TCU, which itself can be controlled by a monitoring system SCS, which can also control the lithography apparatus LA, for example, via a lithography control unit LACU.

[0036] To ensure that the substrate W exposed by the lithography equipment LA is exposed correctly and consistently, it is desirable to inspect the substrate to measure properties of the patterned structure, such as overlap error between subsequent layers, line thickness, critical dimension (CD), etc. For this purpose, an inspection tool (not shown) can be included in the lithography unit LC. If an error is detected, adjustments can be made, for example, to the exposure of subsequent substrates or to other processing steps to be performed on the substrate W, especially if the inspection is performed before other substrates W in the same batch or batch are still to be exposed or processed.

[0037] An inspection device, also known as a metrology device, is used to determine the properties of a substrate W, and specifically, how the properties of different substrates W vary or how the properties associated with different layers of the same substrate W vary layer by layer. Alternatively, the inspection device can be configured to identify defects on the substrate W, and can be, for example, part of a photolithography unit LC, or integrated into a photolithography apparatus LA, or even a stand-alone device. The inspection device can measure properties on latent images (images in a resist layer after exposure), or semi-latent images (images in a resist layer after the post-exposure baking (PEB) step), or developed resist images (where exposed or unexposed portions of the resist have been removed), or even etched images (after a pattern transfer step such as etching).

[0038] Typically, the patterning process in photolithography (LA) equipment is one of the most critical steps in the process, requiring high precision in the dimensional marking and placement of structures on the substrate W. To ensure this high precision, three systems can be combined in a single assembly, such as... Figure 3 The diagram illustrates a so-called "holistic" control environment. One of these systems is the lithography apparatus LA, which is (virtually) 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 provide 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, focal length, overlay accuracy) within which a specific manufacturing process produces a defined result (e.g., a functional semiconductor device)—typically, within which variations in process parameters are allowed in either the lithography or patterning process.

[0039] The computer system CL can use a portion of the design layout to be patterned to predict which resolution enhancement techniques will be used and perform computational lithography simulations and calculations to determine which mask layout and lithography equipment settings will achieve the maximum total process window (in the patterning process). Figure 3(Depicted by double arrows in the first scale SC1). Typically, resolution enhancement techniques are configured to match the patterning possibilities of the lithography equipment LA. The computer system CL can also be used to detect where the lithography equipment LA is currently operating within the process window (e.g., using input from the metrology tool MT) to predict whether suboptimal processing (in...) is the cause. Figure 3 The defect is due to the arrow pointing to "0" in the second scale SC2.

[0040] The measurement tool (MT) can provide input to the computer system (CL) for accurate simulation and prediction, and, for example, in the calibration state of the lithography equipment (LA), can provide feedback to the lithography equipment (LA) to identify possible drift (in...). Figure 3 (The middle part is depicted by multiple arrows in the third ruler SC3).

[0041] In photolithography, it is desirable to frequently measure the created structure, for example, for process control and verification. The tools used to perform these measurements are generally referred to as metrology tools (MTs). Different types of metrology tools (MTs) for this purpose 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 means of a sensor located in the pupil or a plane conjugate to the pupil of the scatterometer's objective lens; these measurements are generally referred to as pupil-based measurements. Alternatively, the measurement of parameters of the photolithography process can be performed by means of a sensor located in the image plane or a plane conjugate to the image plane; in this case, the measurements are generally referred to as image- or field-based measurements. Such scatterometers and related measurement techniques are further described in patent applications US20100328655, US2011102753A1, US20120044470A, US20110249244, US20110026032, or EP1,628,164A, which are incorporated herein by reference in their entirety. The aforementioned scatterer can use light from soft X-rays and the visible near-infrared wavelength range to measure the grating.

[0042] In the first embodiment, the scatterer MT is an angle-resolved scatterer. In such a scatterer, reconstruction methods can be applied to the measurement signal to reconstruct or calculate the properties of the grating. For example, this reconstruction can be obtained by simulating the interaction of scattered radiation using 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 the pattern observed from the real target.

[0043] 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 a target, and reflected or scattered radiation from the target is directed to a spectroscopic detector that measures the spectrum of the specularly reflected radiation (i.e., a measurement of intensity as a function of wavelength). Based on this data, the structure or profile of the target causing the detected spectrum can be reconstructed, for example, through rigorous coupled-wave analysis and nonlinear regression or by comparison with a simulated spectral library.

[0044] In the third embodiment, the scatterer MT is an elliptically polarized scatterer. This elliptically polarized scatterer allows for the determination of lithography process parameters by measuring the scattered radiation for each polarization state. Such a metrology device emits polarized light (such as linear, circular, or elliptical) by using, for example, a suitable polarization filter in the illumination area of ​​the metrology device. A source suitable for the metrology device can also provide polarized radiation. Various embodiments of existing elliptically polarized scatterers 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, which are incorporated herein by reference in their entirety.

[0045] Figure 4 A measurement device such as a scatterer SM1 is described. It includes a broadband (white light) radiation projector 2 that projects radiation onto a substrate. The reflected or scattered radiation is passed to a spectrometer detector 4, which measures the spectrum 6 of the specularly reflected radiation (i.e., a measurement of intensity as a function of wavelength). Based on this data, it can be processed by a processing unit PU, for example through rigorous coupled-wave analysis and nonlinear regression, or through... Figure 3 The simulated spectral library shown at the bottom is used to reconstruct the structure or profile of the detected spectrum. Typically, for reconstruction, the general form of the structure is known, and some parameters are assumed based on knowledge of the process of manufacturing the structure, leaving only a few parameters of the structure to be determined by the scattering measurement data. This scatterometer can be configured as a vertically incident scatterometer or an obliquely incident scatterometer.

[0046] The overall measurement quality of lithographic parameters measured by means of a measurement target is determined at least in part by the measurement formulation used to measure those lithographic parameters. The term "substrate measurement formulation" 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 formulation 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 orientation of the radiation relative to the pattern on the substrate, etc. One of the criteria used to select the measurement formulation can be, for example, the sensitivity of one of the measurement parameters to processing variations. Further examples are described in U.S. Patent Application US2016-0161863 and published U.S. Patent Application US2016 / 0370717A1, which are incorporated herein by reference in their entirety.

[0047] Another type of metrology tool used in IC manufacturing is a topography measurement system, a level sensor, or a height sensor. This tool can be integrated into a photolithography apparatus to measure the topography of the top surface of a substrate (or wafer). A topography map of the substrate (also called a height map) can be generated based on these measurements, which indicate the substrate height as a function of position on the substrate. This height map can then be used to correct the substrate position during pattern transfer on the substrate to provide a spatial image of the patterning apparatus in the appropriate focused position on the substrate. It should be understood that “height” as used herein refers to the generalized dimension from the plane to the substrate (also known as the Z-axis). Typically, the level or height sensor performs measurements at a fixed position (relative to its own optical system), and the relative movement of the level or height sensor between the substrate and the optical system results in a height measurement at a position across the substrate.

[0048] exist Figure 5 The image schematically illustrates an example of a level or height sensor LS known in the art. Figure 5 Only the operating principle is shown. In this example, the horizontal sensor includes an optical system comprising a projection unit LSP and a detection unit LSD. The projection unit LSP includes a radiation source LSO that provides a radiation beam LSB, which is imparted by a projection grating PGR of the projection unit LSP. The radiation source LSO can be, for example, a narrowband or broadband radiation source, such as a supercontinuum light source, polarized or unpolarized, pulsed or continuous, such as a polarized or unpolarized laser beam. The radiation source LSO can include multiple radiation sources with different colors or wavelength ranges, such as multiple LEDs. The radiation source LSO of the horizontal sensor LS is not limited to visible radiation, but may additionally or alternatively cover UV and / or IR radiation and any range of wavelengths suitable for reflection from the substrate surface.

[0049] The projection grating (PGR) is a periodic grating comprising a periodic structure that results in a periodically varying intensity of the radiation beam BE1. The radiation beam BE1 with its periodically varying intensity is guided to a measurement position MLO on the substrate W, having an incident angle ANG between 0 and 90 degrees (typically between 70 and 80 degrees) relative to an axis perpendicular to the surface of the incident substrate (Z-axis). At the measurement position MLO, the patterned radiation beam BE1 is reflected by the substrate W (indicated by arrow BE2) and guided to the detection unit LSD.

[0050] To determine the height level at the measurement position MLO, the level sensor also includes a detection system comprising a detection grating DGR, a detector DET, and a processing unit (not shown) for processing the output signal of the detector DET. The detection grating DGR may be the same as a projection grating PGR. The detector DET generates a detector output signal indicating the received light (e.g., the intensity of the received light), such as a photodetector, or generates a detector output signal representing the spatial distribution of the received intensity, such as a camera. The detector DET may include any combination of one or more detector types.

[0051] The height level at the measurement location MLO can be determined using triangulation techniques. The detected height level is typically related to the signal strength measured by the detector DET, which has a periodicity depending on factors such as the design of the projection grating PGR and the (tilted) incident angle ANG.

[0052] The projection unit LSP and / or the detection unit LSD may include additional optical elements, such as lenses and / or mirrors (not shown), along the path of the patterned radiation beam between the projection grating PGR and the detection grating DGR.

[0053] In one embodiment, the detection grating DGR can be omitted, and the detector DET can be placed where the detection grating DGR is located. This configuration provides more direct detection of the image of the projection grating PGR.

[0054] In order to effectively cover the surface of the substrate W, the horizontal sensor LS can be configured to project an array of measurement beams BE1 onto the surface of the substrate W, thereby generating an array or spot of measurement area MLO covering a large measurement range.

[0055] For example, US7265364 and US7646471 disclose various height sensors of general types, both of which are incorporated herein by reference. US2010233600A1 discloses a height sensor that uses UV radiation instead of visible or infrared radiation, which is also incorporated herein by reference. WO2016102127A1, incorporated by reference, describes a compact height sensor that uses a multi-element detector to detect and identify the position of a grating image without requiring the detection of the grating itself.

[0056] Another type of metrology tool used in IC manufacturing is the alignment sensor. Therefore, a key aspect of the performance of a lithography device is its ability (using the same or different lithography devices) to correctly and accurately align the applied pattern relative to features laid in the previous layer. For this purpose, the substrate is provided with one or more sets of marks or targets. Each mark is a structure whose position can be measured later using a position sensor (typically an optical position sensor). The position sensor can be called an "alignment sensor," and the marks can be called "alignment marks."

[0057] Photolithography apparatuses may include one or more alignment sensors that can precisely measure the position of alignment marks formed on a substrate. Alignment (or position) sensors can use optical phenomena such as diffraction and interference to obtain positional information from alignment marks formed on the substrate. Examples of alignment sensors used in current photolithography apparatuses are based on self-reference interferometers as described in US6961116. Various enhancements and modifications of position sensors have been developed, for example, as disclosed in US2015261097A1. All of these disclosures are incorporated herein by reference.

[0058] Figure 6 This is a schematic block diagram of an embodiment of a known alignment sensor AS, such as described in US6961116, which is incorporated herein by reference. A radiation source RSO provides a radiation beam RB of one or more wavelengths, which is directed by a steering optics onto a marker (such as a marker AM located on a substrate W) as an illumination spot SP. In this example, the steering optics include a spot mirror SM and an objective lens OL. The diameter of the illumination spot SP illuminating the marker AM may be slightly smaller than the width of the marker itself.

[0059] Radiation diffracted by the alignment mark AM (via objective lens OL in this example) is collimated into an information-carrying beam IB. The term "diffraction" is intended to include zero-order diffraction from the mark (which may be referred to as reflection). A self-referenced interferometer SRI (such as the type disclosed in US6961116 above) causes the beam IB to interfere with itself, after which the beam is received by a photodetector PD. Additional optics (not shown) may be included to provide a separated beam in cases where the radiation source RSO generates more than one wavelength. The photodetector may be a single element, or it may comprise multiple pixels, if desired. The photodetector may include a sensor array.

[0060] In this example, the steering optics of the speckle reflector SM can also be used to block zero-order radiation reflected from the marker, so that the information-carrying bundle IB includes only higher-order diffraction radiation from the marker AM (this is not necessary for the measurement, but improves the signal-to-noise ratio).

[0061] The intensity signal SI is provided to the processing unit PU. Through a combination of optical processing in the block SRI and computational processing in the unit PU, the values ​​of the X- and Y-positions on the substrate relative to the reference frame are output.

[0062] A single measurement of this type fixes the position of the mark within a specific range corresponding to a spacing of the mark. Coarser measurement techniques are used in conjunction with this to identify which period of the sine wave contains the mark position. The same process at coarser and / or finer levels can be repeated at different wavelengths to improve the accuracy and / or robustness of mark detection, regardless of the material on which the mark is made and the material on and / or under which the mark is applied. Wavelengths can be optically multiplexed and demultiplexed for simultaneous processing, and / or they can be multiplexed via time-division or frequency-division multiplexing.

[0063] In this example, the alignment sensor and spot SP remain stationary, while the substrate W moves. Therefore, the alignment sensor can be firmly and precisely mounted to the reference frame while effectively scanning the mark AM in the direction opposite to the direction of movement of the substrate W. The movement of the substrate W is controlled by mounting the substrate W on a substrate support and a substrate positioning system that controls the movement of the substrate support. A substrate support position sensor (e.g., an interferometer) measures the position of the substrate support (not shown). In one embodiment, one or more (alignment) marks are provided on the substrate support. Measurement of the position of the marks provided on the substrate support allows calibration of the position of the substrate support determined by the position sensor (e.g., relative to the frame to which the alignment system is attached). Measurement of the position of the alignment marks set on the substrate allows determination of the position of the substrate relative to the substrate support.

[0064] For optical semiconductor metrology, in inspection applications such as any of the aforementioned metrology tools, a bright light source that outputs coherent radiation (while simultaneously covering a wide wavelength range, e.g., from UV to IR) is generally preferred. Such a broadband light source helps improve the flexibility and robustness of the application by allowing optical inspection of wafers with different material properties in the same setup / system without any hardware changes (e.g., changing the light source to have a specific wavelength). Allowing wavelength optimization for specific applications also means that measurement accuracy can be further improved.

[0065] Gas lasers that emit multiple wavelengths simultaneously based on the gas discharge effect can be used in these applications. However, inherent problems associated with gas lasers, such as high intensity instability and low spatial incoherence, may make them unsuitable. Alternatively, the outputs from multiple lasers with different wavelengths (e.g., solid-state lasers) can be spatially combined into the optical path of a measurement or inspection system to provide a multi-wavelength source. The increasing complexity and high implementation cost with the increasing number of wavelengths required hinder the widespread use of this solution. In contrast, fiber-based broadband or white light lasers, also known as supercontinuum lasers, are capable of emitting radiation with high spatial coherence and a wide spectral coverage, such as from UV to IR, making them a very attractive and practical choice.

[0066] Hollow-core photonic crystal fiber (HC-PCF) is a special type of optical fiber consisting of a central hollow core region and an inner cladding structure surrounding the hollow core, both extending along the entire fiber axis. The light guidance mechanism is achieved by the inner cladding waveguide structure, which may include, for example, thin-walled glass elements. Therefore, radiation is primarily confined within the hollow core and propagates along the fiber in a transverse core mode.

[0067] Several types of HC-PCFs can be designed, each based on a different physical guidance mechanism. Two such HC-PCFs include: hollow-core photonic bandgap fiber (HC-PBF) and hollow-core anti-resonant reflective fiber (HC-ARF).

[0068] HC-PCFs comprise hollow channels filled with fluid, enabling them to possess the desired properties for a variety of optical guiding applications; for example, high-power beam delivery using HC-PBFs and gas-based white light generation (or supercontinuum generation) using HC-ARFs. Details regarding the design and fabrication of HC-PCFs can be found in U.S. Patent US2004175085 (for HC-PBFs) and International PCT Patent Application WO2017032454 (for HC-ARFs), which are incorporated herein by reference. HC-PBFs are configured to provide low-loss but narrow-bandwidth optical guiding via a photonic bandgap effect established by the cladding structure surrounding a central hollow core. However, HC-ARFs are designed to significantly broaden the transmission bandwidth via anti-resonant reflection of light from the cladding.

[0069] Figure 7 Many known types of HC-PCF are depicted in cross-section, and examples of HC-PCF are provided. The concepts disclosed herein can be combined for and / or applied to HC-PCF. Figure 7 (a) shows a Kagome optical fiber including a Kagome lattice structure. Figure 7 (b) shows a single-ring or revolver fiber, wherein the hollow core region is formed and surrounded by a non-contact ring layer.

[0070] Figure 7 (c) A cross-section of another practical example of the HC-PCF disclosed in WO2017032454 above is shown. Circles represent solid material, such as quartz glass or silica, in the ARE or cladding region, while shaded areas do not contain solid material (vacuumed or filled with gas or liquid). The HC-PCF includes a hollow region 10 (in Figure 7 (c) Indicated by the dashed circle, the inner cladding region 20 has multiple anti-resonant elements (AREs) 21, and the outer cladding region 30. The hollow region 10 is the empty space between the AREs 21, extending along the longitudinal length of the HC-PCF and having a minimum transverse core dimension D. The AREs 21 of the inner cladding region 20 may include capillaries having a wall thickness t and a minimum transverse ARE dimension d. The AREs 21 may be fixed to the inner surface of the outer cladding region 30. The outer cladding region 30 may include a larger capillary, made of, for example, glass, and providing a closed cladding for the HC-PCF. Figure 7 (c) HC-PCF illustrates an embodiment in which ARE21 comprises a single ring of six thin-walled capillaries with a circular cross-section, the six thin-walled capillaries being arranged in a sixfold symmetry pattern within the larger capillaries of the outer cladding region 30 to create a central hollow core with a diameter of D (the shortest distance between ARE21s that are diametrically opposed).

[0071] It can be modified as follows Figure 7 (c) shows an example of the HC-PCF of the present invention, particularly concerning the number of AREs 21. For example, the AREs may be numbered 4, 5, 7, or more. The arrangement of the AREs may vary in a variety of other ways. Each ARE 21 may have, for example, an elliptical or polygonal cross-section; the internal shape of the outer cladding 30 may have, for example, a polygonal cross-section; and the solid material of the AREs 21 may include, for example, a plastic material such as PMA, glass, such as silica, or soft glass.

[0072] For gas-based white light generation, HC-PCF can be included in a gas chamber designed to operate at pressures, for example, up to many 10 bar (e.g., between 100 bar). When pumped by an ultrashort pump laser pulse with sufficient peak power, the gas-filled HC-PCF can act as an optical frequency converter. The frequency conversion from the ultrashort pump laser pulse to a broadband laser pulse is achieved through the complex interaction of dispersion and nonlinear optical processes within the gas-filled fiber. The converted laser pulse is confined primarily in the hollow core in the form of a transverse core mode and guided to the fiber end. A portion of the radiation (e.g., higher-order transverse core modes or specific wavelengths) may leak from the hollow core through the inner cladding waveguide structure and undergoes strong attenuation during its propagation along the fiber. The core and cladding regions of the HC-PCF can be configured such that the higher-order core modes are phase-matched with the higher-order cladding modes.

[0073] The spatiotemporal propagation characteristics (e.g., spectral amplitude and phase) of a laser pulse propagating along an HC-PCF can be altered and tuned by adjusting pump laser parameters, filling gas parameters, and fiber parameters. These propagation characteristics may include one or more of the following: output power, output mode distribution, output time distribution, width of the output time distribution (or output pulse width), output spectral distribution, and bandwidth of the output spectral distribution (or output spectral bandwidth). The pump laser parameters may include one or more of the following: pump wavelength, pump pulse energy, pump pulse width, pump pulse repetition rate, or pump pulse shape. The fiber parameters may include one or more of the following: fiber length, hollow core size and shape, cladding structure size and shape (or number of capillaries), and thickness of the walls surrounding the hollow core. The filling gas parameters may include one or more of the following: gas type, gas pressure, and gas temperature. The fiber and / or gas parameters also vary along the fiber; for example, the fiber may be tapered or a gas gradient may be present.

[0074] The filler gas can be a rare gas, such as argon, krypton, and xenon; a Raman-active gas, such as hydrogen, deuterium, and nitrogen; or a mixture of gases, such as an argon / hydrogen mixture, a xenon / deuterium mixture, a krypton / nitrogen mixture, or a nitrogen / hydrogen mixture. Depending on the type of filler gas, nonlinear optical processes can include modulation instability (MI), soliton splitting, Kerr effect, Raman effect, and dispersive wave generation, details of which are described in WO2018 / 127266A1 and US9160137B1 (both incorporated herein by reference). Since the dispersion of the filler gas can be tuned by changing the chamber pressure, the dynamic characteristics of the generated broadband pulse and the associated spectral broadening characteristics can be adjusted to optimize frequency conversion. The generated broadband laser output can cover wavelengths from UV (e.g., <200 nm) to mid-IR (e.g., >2000 nm).

[0075] like Figure 8 As shown, the broadband light source device 100 includes a pump laser 110 that outputs a pump pulse sequence 111, an optical component 120 for spectrally broadening the input pump pulses, and an optical diagnostic device 130 for measuring the output broadband spectrum. The optical component 120 includes an HC-PCF (e.g., HC-ARF) 101 with a specific fiber length and a gas chamber 102 filled with a working gas or gas mixture at a specific pressure or with a certain pressure distribution. The gas chamber 102 also includes an input optical window 103a and an output optical window 103b located at corresponding ends of the gas chamber 102. The input optical window 103a is operable to allow ultrashort pump laser pulses to enter the gas chamber 102 via the window. After being coupled into the gas-filled HC-PCF 101, the pump laser pulses 111 propagate along the fiber, where they undergo significant spectral broadening. The resulting broadband laser pulse is then discharged from the gas chamber 102 via the output optical window 103b and measured by the optical diagnostic device 130 (e.g., a spectrometer).

[0076] To fill the HC-PCF 101 with the working gas, the gas chamber 102 can be connected to a pressurized gas supply or storage device (not shown). The inner surface of the wall and the input optical window 103a and output optical window 103b of the gas chamber 102 enclose the cavity. The axis of the gas chamber is parallel to the axis of the HC-PCF 101.

[0077] Typically, HC-PCFs (when used in the measurement applications described herein) are supported at least at both ends using mountings that position the fiber relative to fixed points within the optical system. Prior art mounting methods involve the use of adhesives, tapes, and clamping forces applied via slotted ferrules, V-grooves, retainers using loaded springs, or magnets. The inventors recently disclosed in Dutch patent application NL2023515A, which is incorporated herein by reference, that the use of these methods is unsuitable for gas-based supercontinuum (or white light) sources. Reasons include adhesive degassing, leading to contamination and reduced lifetime, and stress inducing on the HC-PCF, which degrades optical performance. NL2023515A shows that these drawbacks can be mitigated by using mountings designed to have a symmetrical stress distribution relative to the internal HC-PCF structure.

[0078] When operating an HC-PCF-based light source, contaminants grow on the end faces of the HC-PCF over time. Specifically, the inventors have observed that contaminant growth primarily occurs on the output face of the HC-PCF. Contaminant growth appears to occur in areas of high light intensity. Contaminant growth also appears to occur where the light spectrum has been broadened; in particular, contaminant growth is not strong on the input face. Furthermore, contaminant growth is primarily observed on the output face of the HC-PCF, rather than within the HC-PCF itself.

[0079] Contaminants may form from windows in the gas chamber or from silica particles ablated from the HC-PCF. These contaminants may undergo photoinduced processes as the broadened output light from the PCF propagates, altering their chemical structure and / or crystallizing on the output surface. After a certain number of operating hours (e.g., after a certain dose (J) of laser energy has been transmitted), this contamination leads to a degradation of the fiber's performance; this degradation can be termed the glassy growth phenomenon (GGP). Alternatively, GGP may involve the movement of silicon (as atoms, or volatile substances such as SiH4) via physical or chemical sputtering and / or plasma-induced or temperature-induced deposition at the output end of the fiber.

[0080] The accumulation of these contaminants shortens the lifespan of the light source. GGP (Glass Plate Gap) at the output surface and the resulting contaminant growth can protrude into the optical path of the diverging beam. This causes scattering of the output light, leading to a decrease in the output power of the light source. GGP shortens the source's lifespan: GGP causes light scattering, thus causing the fiber to lose its performance. For example, this may result in the sensor's required photon budget not being met after a certain period. Furthermore, GGP causes drift in the light source's power / spectral density and mode distribution, which, if unresolved, will require frequent recalibration. Thus, the short lifespan of the fiber implies frequent fiber replacement in the field.

[0081] To reduce contaminant growth on the end faces of HC-PCF, the capillaries of HC-PCF can be collapsed. The tapered end of the capillary can prevent contaminant growth. However, this solution does not address the potential problem of contaminants in the device and cannot completely prevent contaminant growth, especially if the tapering in the capillary is not perfect.

[0082] Improved methods and arrangements for increasing the lifetime of HC-PCF will now be described. In some embodiments, this may include improved methods of mounting the HC-PCF within a supercontinuum radiation source. Other methods may include improving the geometry of the HC-PCF to reduce GGP formation.

[0083] HC-PCF bulb

[0084] In the first embodiment, it is proposed to completely omit the gas chamber 102. Instead, it is proposed to use the hollow region within the HC-PCF 101 (i.e., within the actual optical fiber) as the main gas reservoir. This concept can be considered similar to that of a conventional light bulb used in lighting applications. Therefore, the HC-PCF arrangement proposed in this embodiment will be referred to as an HC-PCF bulb throughout the description.

[0085] Figure 9 An end of an HC-PCF bulb 900, 900' according to a combination of two such embodiments is shown. In each case, the other end may be substantially similar, or the HC-PCF optical fiber 910 may have a [missing information - likely a design element] at one end. Figure 9 (a) arrangement, having at the other end Figure 9 (b) arrangement (or any other combination falling within the scope of this disclosure).

[0086] In each embodiment, the end of the HC-PCF fiber 910 includes an end section or outer capillary 920, 920' and an end cap 930. The outer capillary 920, 920' includes, at least a portion thereof, an inner diameter larger than the inner diameter of the HC-PCF fiber 910. Figure 9 In embodiment (a), the outer capillaries 920, 920' can be spliced ​​to each end of the HC-PCF fiber 910 and sealed by an end cap (e.g., a transparent window) 930. The end cap 930 can be made of glass, for example. The end cap 930 may also include an input lens at one end for coupling into the pump beam and / or an output lens at the other end for collimating the output beam (or alternatively, the lenses may be separate).

[0087] exist Figure 9In (a), the outer capillary 920 includes tapered outer capillary 920, each tapered outer capillary tapering outwards (e.g., defining an expanding inner diameter from the inner diameter of the HC-PCF fiber outer capillary (or outer sheath) 925 along the length of the HC-PCF fiber 910 toward the end cap 930). This is because the ultrashort laser beam of the pump laser may irreversibly damage the end cap directly attached to the HC-PCF fiber 910. Additionally, the local capillary diameter should be significantly larger than the focused / divergent laser beam at the input / output ends. Figure 9 In (b), the end segment or outer capillary 920' includes a substantially uniform inner diameter that is larger than the inner diameter of the HC-PCF fiber outer capillary 925. It is understood that these are merely examples, and any configuration for which at least a portion of the end segment has a larger inner diameter, such that the divergent broadband radiation emitted from the HC-PCF fiber 910 is not blocked by the corresponding end segment in the axial propagation direction from the end of the HC-PCF fiber 910 (or the focused pump radiation is not blocked from entering the HC-PCF fiber 910), falls within the scope of this disclosure.

[0088] The splicing of the outer capillaries 920, 920' to the HC-PCF fiber 910 can be performed in a relatively straightforward manner using commercially available fiber splicers (e.g., using an electric arc, an electrically heated wire), or alternative methods such as flame or laser. During the splicing of the end capillaries 920, 920' to the outer capillaries 925 of the HC-PCF fiber, the inner capillaries of the HC-PCF fiber 910 can collapse, forming a widened or tapered core region 940 (expanding the hollow core diameter toward the fiber end). This can improve the lifetime of the supercontinuum light source, as described in European patent application EP 17171468, which is incorporated herein by reference. The splicing of the end cap 930 to the end capillaries 920, 920' can be similarly achieved. Alternatively, the collapse of the inner capillaries can be performed in an initial step, followed by a second step of splicing.

[0089] Pressurized gas should be filled into the HC-PCF before the final splicing. Because pressures of tens of bar are required, any heat dissipated into the glass could cause the fiber to expand. Established methods for manufacturing pressurized glass bulbs or plasma lamps can be applied to manufacture the HC-PCF bulb 900 as disclosed herein. Such a method may include inserting the HC-PCF bulb 900 (before final splicing) into an emptied container (to remove any air from the HC-PCF bulb 900) and flushing the HC-PCF bulb 900 with pressurized gas. The final splicing is then performed in a high-pressure environment to prevent localized expansion of the HC-PCF fiber 910. If the splicing forms a leak-proof connection, the pressurized gas will remain confined when the HC-PCF bulb 900 is removed from the container. An alternative method may include inserting a nozzle between one of these connections (e.g., the connection between end caps 920, 920' and end cap 930) and using the nozzle to inject pressurized gas. By heating the optical fiber while rapidly removing the nozzle, the last opened connection can be sealed, while pressurized gas is maintained within the HC-PCF bulb 900.

[0090] While the working gas primarily consists of relatively large atoms (e.g., krypton) with low diffusion in silica, hydrogen may be initially added to help increase the lifetime of the HC-PCF bulb 900. This hydrogen will tend to diffuse out of the HC-PCF bulb 900 more rapidly. In some applications, the HC-PCF bulb 900 may be inserted into an environment with the same or similar partial pressure of hydrogen as initially present within the HC-PCF bulb 900. The gas consumption of the HC-PCF bulb 900 is ultimately provided by the solubility and diffusivity of the working gas in fused silica (or more generally, the HC-PCF bulb 900 material) and the fidelity of the splice points where the end capillaries 920, 920' are spliced ​​to the main HC-PCF fiber 910 (in this embodiment). The elimination of any O-ring connections (or sealants or adhesives of various materials) compared to an external gas chamber reduces gas leakage.

[0091] Although the axial dimension HC-PCF 900 is relative to Figure 8 The conventional gas chamber arrangement remains unchanged, but the lateral dimensions can be reduced to the sub-millimeter level. Compared to the current gas chamber concept (5cm diameter), this reduces the cross-sectional diameter by approximately 20 to 100 times. The minimized gas volume and tubular design improve safety compared to the current gas chamber concept.

[0092] The entire low-capacity gas reservoir of the HC-PCF bulb 900 minimizes the number density of atoms / molecules in the working gas. Therefore, the amount of contaminants is significantly reduced. Compared to a typical gas chamber, the contaminant number density can be reduced by 100 times or more (e.g., it is actually smaller than the currently typical diameter when assuming a gas chamber diameter of 1 mm, and the hollow diameter of the HC-PCF bulb 900 disclosed herein is 0.1 mm). Furthermore, the HC-PCF bulb 900 can be made of inert materials (silica and the working gas). Therefore, any contaminants from unclean surfaces (e.g., from lubricants used during the production of metal gas chambers) or from organic molecules from the O-ring are avoided.

[0093] To mount the HC-PCF bulb 900, it can be clamped at a point on the capillary tubes 920 and 920'. This avoids any mechanical stress on the actual waveguide (fiber 940). This should allow for the use of an industrialized mounting concept compared to the special mounting required for installing the HC-PCF in an external gas chamber.

[0094] In the external gas chamber, the polymer coating of the HC-PCF optical fiber should be carefully removed, as degassing would otherwise contaminate the gaseous environment and reduce the lifespan of the supercontinuum light source. In the HC-PCF bulb 900 disclosed herein, the fiber coating can preferably be kept intact, or even reinforced for additional protection (e.g., using a recoating machine). This increases stability and protects the HC-PCF bulb 900 from environmental influences (e.g., scratches, mechanical shocks).

[0095] The cost of this HC-PCF bulb 900 is expected to be lower compared to an external chamber design. The production costs associated with a metal chamber are eliminated. Of course, while there will be production costs for the HC-PCF bulb 900, material costs will be largely negligible, as it only involves glass and the required machinery does not include cost-intensive machining tools (e.g., CNC machines).

[0096] Sleeve-type HC-PCF for improved installation

[0097] As already described, NL2023515A describes a number of mounting devices that provide a more symmetrical stress distribution than conventional mounting devices. NL2023515A discloses a mounting arrangement and installation device for a hollow fiber including an HC-PCF, wherein the mounting device includes a plurality of mounting contacts configured to apply force to the outer layer of the hollow fiber. A portion of the hollow fiber is located in the receiving region of the mounting device. The plurality of mounting contacts are disposed around the receiving region. The mounting contacts are distributed around the receiving region in a manner corresponding to the distribution of characteristics of the microstructure of the hollow fiber. In particular, the distribution of the mounting contacts can ensure a symmetrical stress distribution (e.g., maximize the symmetry of the stress distribution).

[0098] Figure 10 An example mounting device disclosed in NL2023515A is shown. An HC-PCF optical fiber 1000 is located within a receiving region 1030 of the mounting device. The mounting device includes a base 1020 and a cover 1040. A force AF (e.g., adjustable) can be applied to the cover 1040 (or both the cover and the base) such that they are pressed towards each other. The force can be applied, for example, via a spring-loaded screw, an electrical arrangement (e.g., via electrostatic attraction using plates with opposite charges on either side of the mounting device), or a magnetic arrangement (e.g., using magnets on either side of the mounting device). The base 1020 may include a groove defining the receiving region 1030. In the example shown, the groove is a V-groove. However, one or more grooves (e.g., complementary grooves may exist in the base 1020 and the cover 1040) may define a receiving region 1030 having a polygonal shape (e.g., pentagonal or hexagonal), a curved shape, or an irregular shape.

[0099] As described in NL2023515A (and as described in that disclosure by) Figure 8 As shown, applying excessively high camping force degrades the optical performance of a supercontinuum light source. However, even when using... Figure 10 When installing optical fibers, the permissible clamping force (i.e., before such performance degradation) may be insufficient to securely mount the fiber, especially against the shocks and vibrations exerted in industrial environments. To achieve higher clamping forces, the fiber mounting concept needs to ensure a more symmetrical stress distribution, or the fiber needs to be more stress-resistant. The former has been proposed in NL2023515A, and significant further improvements in stress distribution symmetry are not feasible in practice. Making the fiber more stress-resistant requires different fiber structures (e.g., larger fiber outer diameters or internal stress absorbers, as disclosed in Dutch patent application NL 2022892A, which is incorporated herein by reference). However, these concepts require experimental validation and may prove challenging to implement.

[0100] This document discloses a hybrid concept in which HC-PCF fiber is inserted into a capillary tube (e.g., a sleeve). The inner diameter of the sleeve is (slightly) larger than the outer diameter of the HC-PCF fiber. It can then be mounted using appropriate mounting hardware (e.g., as disclosed in NL 2023515A and...). Figure 10 (Any of the mounting components shown) securely clamps the sleeve. The advantage of this arrangement is that the clamping force can be relatively strong (e.g., industrially viable and stronger than that that could be when applied directly to the fiber), without being applied directly to the HC-PCF, and therefore without impairing optical performance.

[0101] Figure 11 Several embodiments based on this concept are shown. In each of the embodiments shown, the HC-PCF fiber 1100 is inserted into a sleeve 1130 at each end. Each of these sleeves may have a slightly tapered profile 1140 at one end. Note that the tapered profile 1140 is optional, and the HC-PCF 1100 may alternatively be incorporated into an axially homogeneous sleeve. In one embodiment, the end of the HC-PCF fiber 1100 may be inserted into the tapered sleeve 1130 until it is flush with the tapered profile 1140 (at contact point 1150). The advantage of this embodiment is that the gap between the HC-PCF fiber 1100 and the sleeve 1130 acts as an additional spring when the sleeve is clamped.

[0102] exist Figure 11 In (a), the HC-PCF fiber 1100 and the sleeve 1130 both terminate at the same position 1160 or nearly at the same position 1160, such that at each end there is little or no sleeve extending beyond the HC-PCF fiber 1100. Figure 11 (a) and (b) show only one end; both ends are similar. Figure 11 (b) illustrates an embodiment in which the sleeve 1130' protrudes 1160' from the end face of the HC-PCF fiber 1100. This improves clamping and has the added benefit of reducing gas turbulence and contaminant buildup, potentially improving system lifetime.

[0103] Figure 11 (c) shows another embodiment in which a single sleeve 1130” is provided extending along the entire fiber 1100, instead of sleeves at each end. In the illustrated embodiment, the fiber may protrude at both ends (in a manner similar to...). Figure 11 (b) shows the arrangement where the end of the sleeve is sealed by an end cap 1170, which includes corresponding transparent windows (e.g., an input window for receiving pump laser radiation and an output window for outputting supercontinuum radiation). In this way, the sleeve can be used as and effectively replace the gas chamber (e.g., Figure 8 (Gas chamber 102). This has the advantage of a smaller volume gas chamber compared to conventional gas chamber arrangements. End cap 1170 may include an input lens at one end for coupling into the pump beam and / or an output lens at the other end for collimating the output beam.

[0104] To ensure the defined clamping, a robust connection should be established between the sleeves 1130, 1130', and 1130” and the HC-PCF 1100; for example, a chemical bond should be formed between the sleeves and the HC-PCF. One proposed method involves collapsing the sleeves 1130, 1130', and 1130” onto the HC-PCF 1100. This can be achieved by using a sleeve material with a lower transition temperature (Tg) than the HC-PCF 1100 material, which typically includes silicon dioxide with a Tg ≈ 1200 °C. As an example, borosilicate glass with a transition temperature of Tg ≈ 165 °C can be used. Other examples include soft glasses, such as chalcogenides or tellurites. However, a lower transition temperature is not necessary, and this method of collapsing the sleeve also works when the sleeve material is the same material as the optical fiber (e.g., silicon dioxide). By locally heating the sleeve-HC-PCF hybrid structure (e.g., by applying heat through a flame, electric heating wire, electric arc, or laser), and simultaneously adjusting the heating intensity and heating time until a strong mechanical connection is achieved, collapse can be achieved without deforming the local HC-PCF structure.

[0105] It should be noted that the collapse of the sleeve on HC-PCF introduces stress. This becomes more pronounced for larger differences in the coefficients of thermal expansion between the materials (the coefficient of thermal expansion of HC-PCF is approximately 0.57 × 10⁻⁶ in the range of 0 to 200°C). -6 / °K; the coefficient of thermal expansion of borosilicates is approximately 5 times greater. Based on known information (e.g., as described in NL2023515A), this could potentially degrade the optical performance of the supercontinuum light source. To address this issue, the embodiments propose a location where the localized collapse can be decoupled from the waveguide region of the HC-PCF. As already described with respect to embodiments of the HC-PCF bulb, the HC-PCF can be processed to create a tapered shape 1110 at both ends (e.g., to improve the lifetime of the supercontinuum light source as described in EP17171468); this can be achieved by collapsing the thin-walled internal capillary before sleeve insertion, thus defining a region where the hollow core diameter increases toward the ends. The inventors have recognized that in this region (which is typically several hundred μm long), the HC-PCF is not actually a waveguide, and therefore this region is locally more stress-resistant. If the collapsed sleeve is within the tapered region 1110, the resulting stress should not (or only to a reduced extent) impair the optical performance while still providing a robust mounting solution.

[0106] Thus, it is proposed that the sleeving HC-PCF (in any of the embodiments described) be assembled with a collapsed sleeving region 1140 (sleeving tapered region) positioned to coincide with the internal tapered region 1110 of the HC-PCF. More specifically, it is proposed that any contact area of ​​the sleeving assembly with the hollow-core photonic crystal fiber is located at or beyond the tapered core region along the axis of the hollow-core photonic crystal fiber (in this document, beyond the tapered core region means beyond the tapered core region in the direction toward the respective end). The contact area between the sleeving 1130 and the fiber 1100 may include an axial length less than and coinciding with the tapered length, such that the contact area and the main waveguide region of the HC-PCF do not coincide along the axial length.

[0107] HC-PCF speaker

[0108] As described, the glass growth phenomenon, which is the main contributor to the finite lifetime of HC-PCF, is mainly seen on the output end face of the fiber, especially at the sharp edges of the capillary and at the edges of the outer capillary or outer sheath covering the fiber.

[0109] In this embodiment, an arrangement will be described that further distances the glass outer sheath of the optical fiber from the diverging beam and / or effectively avoids any open glass sections at the fiber endface. This arrangement allows the hollow core to remain open, enabling downstream use of the beam. This modified optical fiber can significantly reduce the growth rate of the glassy material because the nucleation / condensation sites are effectively moved away from the strong electric field of the beam.

[0110] To achieve this modified optical fiber, it is recommended to create a horn shape at the fiber end. This arrangement can be similar to some of the HC-PCF bulb embodiments described above, but without a sealed end cap (e.g., so that the fiber of this embodiment can be used in a more conventional air chamber arrangement). The horn shape can be formed, for example, by shaping the fiber output end section or attaching / joining a suitably shaped output end section.

[0111] Thus, the output end section of the HC-PCF fiber may include, at least a portion of the output end section, an inner diameter larger than the inner diameter of the outer capillary / sheath along the central portion of the hollow-core photonic crystal fiber preceding the output end section. This central portion may involve the main part of the fiber length, or the inner diameter at half the length along the HC-PCF. Essentially, within the central portion between any tapered inner capillary or any enlarged end section, the HC-PCF inner diameter can generally be nominally constant along its length, ignoring any undesirable variations due to processing defects / variations or damage over time.

[0112] The core's inner and outer diameters before expansion were 30 ± 10 μm and 125 ± 25 μm, respectively. After expansion, these dimensions can vary depending on the manufacturing method used, but the core's inner diameter D... core It can be used in the range of 100μm to 4.5mm and with an outer diameter D outer The range is from 150 μm to 7 mm. More specific ranges for each manufacturing method will be described below.

[0113] Figure 12 A schematic diagram of one end of an HC-PCF fiber F is shown, wherein the fiber end (i.e., the inner capillary or anti-resonance element ARE and the outer capillary or outer sheath OJ) is tapered outwards; that is, away from the longitudinal axis of the fiber. Furthermore, the inner capillary ARE can be located in this outwardly tapered region (along length L). tp The internal capillary ARE is collapsed in the extended region. The internal capillary ARE can extend to the fiber end as shown, or it can be terminated before the end. In the latter case, the internal capillary can be incorporated into the outer sheath OJ to avoid forming a nucleation side for glass growth. For example, such an HC-PCF fiber F can be used as described below and... Figure 14 It is manufactured by any of the glass blowing methods shown in (a) and 14(b).

[0114] Figure 13 The diagram shows a glass horn TP (manufactured separately) along length L. tp An HC-PCF fiber F (extended) is provided, with the glass horn TP attached (e.g., mating or splicing) to fiber F. The internal capillary ARE of the fiber can be collapsed and, as shown, can also be incorporated into the outer sheath OJ. In this embodiment, the open glass cross-section at the fiber end can be avoided or at least considerably reduced. For example, such an HC-PCF fiber F can use the method described below and... Figure 14 It is manufactured using any of the splicing methods shown in (c), 14(d) and 14(e).

[0115] Several methods for manufacturing the horn end of this embodiment will now be described. It should be noted that these methods can also be used to manufacture the HC-PCF bulb embodiment described above, in which an additional step is to fill the optical fiber with a working gas and attach / sponge an end cap or window to seal it in the working gas. Both methods rely on generating a pressure difference between the inside and outside of the optical fiber while heat is applied; also known as glass blowing. These two other methods rely on separately creating the horn shape and fusing it to the end face of the optical fiber.

[0116] Figure 14(a) Schematarily illustrates the arrangement of a first glass-blowing example, where glass blowing is performed after cleaving. In current fiber processing, the final step may include cleaving the fiber after internal capillary thinning. To create a horn shape at the fiber end, it is recommended to bring the tip of the fiber F close to the counter body CB (which may be, for example, a large-diameter solid fiber) and apply gas pressure to the other end of the fiber F. In the example shown, gas pressure is applied using a gas reservoir GR or a gas source and pressure regulator PR, which can be introduced into the fiber F via a pressure cap PC. If the distance to the fiber tip creates a major constraint on flow, the counter body CB allows pressure to be built up at the fiber tip. This distance may be, for example, 5 μm or less, since the inner diameter of the fiber is ~30 μm. However, note that the counter body CB should not come into contact with the fiber tip to avoid fusion or uncontrolled deformation of the geometry. Once close and under pressure, the fiber tip can be heated to a softening temperature by a heat source HS, at which the fiber will expand radially outward. The entire process can be performed in conventional or commercially available splicers. In such a splicer, the heat source can be, for example, an electric arc discharge or a CO2 laser. For instance, after expansion, the core diameter D... core It can be between 100μm and 450μm and the outer core diameter D outer Between 150μm and 500μm. Horn length L tp The value can also be between 150μm and 500μm, and can be similar to D. outer The actual value.

[0117] Figure 14 (b) A schematic illustration shows an arrangement of a second glass-blowing example, wherein glass blowing is performed prior to splitting. This arrangement expands the fiber end by applying pressure to the fiber before it is splitted to its final length. This can be combined with or as an alternative to any tapering step used to gradually taper the internal capillary ARE. The fiber can be locally blown up to generate small bubbles by applying pressure to the fiber via a gas reservoir GR and local heating via a heat source HS. After bubble generation, the fiber can be splitted at a location along the length of the bubble (e.g., at or around the widest point of the bubble) to obtain a horn-shaped fiber end. This method can lead to... Figure 14 (a) The method described is similar for values ​​of core diameter and horn length.

[0118] Figure 14(c) illustrates a first step of the first manufacturing method, wherein the horn-end segment is manufactured as a separate component, for example, from a capillary fiber CF. The capillary fiber CF may, for example, have an outer diameter of approximately 1 mm. A tapered shape is created by applying a heat source HS while drawing the fiber from both ends. The tapering should be such that the inner diameter at (or around) the waist of the tapering matches the inner diameter of the HC-PCF. The tapered capillary is split (e.g., at the point where the inner diameter of the capillary fiber CF matches the inner diameter of the HC-PCF). Figure 14 As shown in (e), once split, the horn-end segment TP can be spliced ​​to the end face of the HC-PCF fiber F. Both manufacturing steps can be performed using a conventional fiber splicer. Based on this method, for example, the core diameter D... core It can be between 300μm and 800μm and the outer core diameter D outer It can be between 700μm and 1200μm. Horn length L tp The value can be between 3mm and 7mm.

[0119] Figure 14 (d) illustrates a first step of the second manufacturing method, wherein the horn-end segment is manufactured as a separate component, for example, from a capillary optical fiber CF. In this method, the horn-end segment TP is formed in an optical fiber drawing tower, wherein glass is drawn through a heat source HS. Figure 14 As shown in (e), once formed, the horn-end segment is spliced ​​to the end face of the HC-PCF in the fiber optic splicer. In this configuration, a larger outer diameter can be achieved compared to the aforementioned embodiments; for example, the inner core diameter D... core It can be on the order of millimeters, for example, between 1.5mm and 4.5mm, and the outer core diameter D outer For example, between 3mm and 7mm. Speaker length L tp The value can be on the order of centimeters, for example, between 1cm and 5cm.

[0120] It should be noted that embodiments of HC-PCF bulbs or horns can be combined with sleeve-type HC-PCF embodiments. For example, HC-PCF bulbs or horns may also include a sleeve (e.g., as shown in the image). Figure 11 (a) or 11(b) shown), which can be added before splicing the conical end or horn end section TP (or before the glass blowing step).

[0121] Further embodiments are discussed in the following numbered clauses:

[0122] 1. An optical component, comprising:

[0123] Hollow-core photonic crystal fiber, comprising an internal capillary for guiding radiation and an external capillary covering the internal capillary; and

[0124] At least one output segment, wherein the inner diameter of at least a portion of the output segment is greater than the inner diameter of the outer capillary along the central portion of the hollow photonic crystal fiber before the output segment.

[0125] 2. The optical component according to Clause 1, wherein the output section is configured such that the divergent broadband radiation emitted from the hollow photonic crystal fiber is not blocked by the output section in the axial propagation direction.

[0126] 3. The optical component according to Clause 1 or 2, wherein the internal capillaries of the hollow photonic crystal fiber are collapsed to define a tapered core region at each end of the hollow photonic crystal fiber, the tapered core region including a region in which the hollow core of the hollow photonic crystal fiber has a diameter that increases toward each end of the hollow photonic crystal fiber.

[0127] 4. The optical component according to clauses 1, 2 or 3 further includes:

[0128] Input section;

[0129] A first transparent end cap and a second transparent end cap seal the respective ends of the hollow photonic crystal fiber; and the gas medium is sealed within the space defined by the hollow photonic crystal fiber, the end section, and the end cap.

[0130] The input section is included between the input end of the hollow-core photonic crystal fiber and the first end cap, and the output section is included between the output end of the hollow-core photonic crystal fiber and the second end cap.

[0131] 5. The optical component according to Clause 4, wherein the input section is configured such that the converging pump radiation allowed to enter the hollow-core photonic crystal fiber is not blocked by the input section in the axial propagation direction.

[0132] 6. In the optical component described in Clause 4 or 5, one or both end sections are tapered end sections that taper outward to define an expanded inner diameter from the hollow photonic crystal fiber toward the corresponding end cap.

[0133] 7. The optical component according to Clause 4 or 5, wherein one or both end segments have a substantially uniform inner diameter between the hollow-core photonic crystal fiber and the corresponding end cap.

[0134] 8. The optical component according to any one of clauses 4 to 7, wherein the first transparent end cap is configured to receive a pump radiation beam to excite the gas medium for supercontinuum generation, and the second transparent end cap is configured to emit an output beam from the supercontinuum generation.

[0135] 9. The optical component according to Clause 8, wherein the first transparent end cap includes an input lens for coupling into the pump radiation beam and / or the second transparent end cap includes an output lens for collimating the output beam.

[0136] 10. The optical component according to any one of clauses 4 to 9, wherein the end cap is composed of silicon dioxide or borosilicate.

[0137] 11. The optical component according to clauses 1, 2 or 3, wherein the output end section is widened outward to define an expanded inner diameter from the hollow-core photonic crystal fiber toward the output end of the output end section.

[0138] 12. The optical component according to Clause 11, wherein the output section includes at least the widened output portion of the external capillary.

[0139] 13. The optical component according to Clause 12, wherein the internal capillary of the hollow photonic crystal fiber is formed away from the longitudinal axis of the optical component at the output end section.

[0140] 14. The optical component according to Clause 13, wherein the internal capillary is mixed into the external capillary at the output section.

[0141] 15. The optical component as described in Clause 11, wherein the output section includes an end section that is spliced ​​to or otherwise joined with the end of a hollow-core photonic crystal fiber.

[0142] 16. The optical component according to any one of clauses 11 to 15, wherein the inner diameter of the output section at its widest point may be any value in the range of 100 μm to 4.5 mm.

[0143] 17. The optical component according to any one of the preceding clauses, wherein the hollow-core photonic crystal fiber includes an optical fiber coating.

[0144] 18. The optical component as described in Clause 17, wherein the fiber coating comprises a polymer.

[0145] 19. The optical component according to any one of the preceding clauses, wherein at least the output section is composed of silicon dioxide or borosilicate.

[0146] 20. A broadband light source device configured to generate broadband output, comprising:

[0147] The optical component according to any one of the foregoing clauses; and

[0148] The mounting device clamps the optical component at one or more points on the end section.

[0149] 21. The broadband light source apparatus according to Clause 20 further includes a pump laser for outputting a plurality of pump pulses to excite the gas medium for supercontinuum generation.

[0150] 22. The broadband light source device according to clause 20 or 21, wherein the broadband output includes a wavelength range of 200 nm to 2000 nm, or a subrange within that range.

[0151] 23. A method of manufacturing an optical component as described in any one of clauses 4 to 10, comprising:

[0152] Each end segment is spliced ​​to the corresponding end of the hollow-core photonic crystal fiber, and each end segment is attached with a corresponding end cap; and

[0153] The optical components are filled using the gaseous medium.

[0154] 24. The method according to Clause 23, wherein the filling of the gaseous medium is performed before the final splicing of the splicing step is performed.

[0155] 25. The method described under Clause 24, comprising:

[0156] Prior to the final assembly, the optical components are inserted into the evacuated container;

[0157] Using pressurized gas to rinse optical components; and

[0158] The final assembly is manufactured in a high-pressure environment.

[0159] 26. The method according to Clause 25, wherein the rinsing step comprises: heating the hollow photonic crystal fiber while removing the nozzle used in the rinsing step.

[0160] 27. A method of manufacturing an optical component as described in any one of clauses 12 to 14, comprising:

[0161] A pressure difference is established between the inner region and the outer region of the hollow photonic crystal fiber, while heat is locally applied to the hollow photonic crystal fiber to cause it to expand in the region where the heat is applied.

[0162] 28. The method according to Clause 27, comprising: initially splitting the output end of a hollow-core photonic crystal fiber; and

[0163] The pressure difference is established by placing a counter body near the output end of the hollow photonic crystal fiber to prevent flow from the output end and introducing fluid at the input end of the hollow photonic crystal fiber.

[0164] 29. The method described under Clause 27, comprising:

[0165] Establish the pressure difference to form bubbles along the length of the hollow photonic crystal fiber, in the region where heat is locally applied; and

[0166] The output end of the hollow photonic crystal fiber is split at the bubble.

[0167] 30. A method of manufacturing the optical component described in Clause 15, comprising:

[0168] A heat source is locally applied to the capillary optical fiber, while tension is applied from both ends of the fiber to create a tapered shape;

[0169] The optical fiber is split at the tapered section to create the output segment; and

[0170] The output section is spliced ​​to the output end of the hollow-core photonic crystal fiber.

[0171] 31. A method of manufacturing the optical component described in Clause 15, comprising:

[0172] The output section is formed in the drawing tower; and

[0173] The output section is spliced ​​to the output end of the hollow-core photonic crystal fiber.

[0174] 32. An optical component, comprising:

[0175] Hollow-core photonic crystal fiber; and

[0176] A sleeve assembly includes at least one sleeve that at least covers a corresponding end portion at each end of the hollow-core photonic crystal fiber; wherein:

[0177] The internal capillaries of the hollow-core photonic crystal fiber are collapsed to define a tapered core region at each end of the hollow-core photonic crystal fiber, the tapered core region comprising a region in which the diameter of the hollow core of the hollow-core photonic crystal fiber increases toward each end of the hollow-core photonic crystal fiber; and

[0178] The sleeve device contacts the contact area of ​​the hollow photonic crystal fiber, and the contact area is located entirely within or beyond the tapered core region relative to the main axis of the hollow photonic crystal fiber.

[0179] 33. The optical component according to Clause 32, wherein the sleeve device includes a first sleeve and a second sleeve, the first sleeve being used to cover a first end portion of the hollow-core photonic crystal fiber, and the second sleeve being used to cover a second end portion of the hollow-core photonic crystal fiber.

[0180] 34. The optical component as described in Clause 33, comprising:

[0181] A gas cell for at least partially enclosing a hollow-core photonic crystal fiber and a sleeve assembly; and

[0182] A gaseous medium is contained within the gas chamber.

[0183] 35. The optical component according to Clause 32, wherein the sleeve device comprises a single sleeve covering the length of the hollow-core photonic crystal fiber.

[0184] 36. The optical component as described in Clause 35, comprising:

[0185] The first transparent end cap and the second transparent end cap, the corresponding ends of the sealing sleeve, and

[0186] The gaseous medium is contained within the sleeve.

[0187] 37. The optical component according to Clause 36, wherein the first transparent end cap is configured to receive a pump radiation beam to excite the gas medium for supercontinuum generation, and the second transparent end cap is configured to emit an output beam generated from the supercontinuum.

[0188] 38. The optical component according to Clause 37, wherein the first transparent end cap includes an input lens for coupling into the pump radiation beam and / or the second transparent end cap includes an output lens for collimating the output beam.

[0189] 39. The optical component according to any one of clauses 32 to 38, wherein the sleeve device extends beyond each end of the hollow photonic crystal fiber.

[0190] 40. The optical component according to any one of clauses 32 to 38, wherein the sleeve device terminates at or near each end of the hollow-core photonic crystal fiber.

[0191] 41. The optical component according to any one of clauses 32 to 40, wherein the sleeve device includes a tapered shape facing the hollow photonic crystal fiber at each end of the hollow photonic crystal fiber facing the contact region.

[0192] 42. The optical component according to any one of clauses 32 to 41, wherein each contact region in the contact region shall have an axial length less than the tapered length of the corresponding tapered core region.

[0193] 43. The optical component according to any one of clauses 32 to 42, wherein the sleeve material comprises borosilicate glass, silicon dioxide, or chalcogenide, tellurite, or other soft glass.

[0194] 44. A method of manufacturing an optical component according to any one of clauses 32 to 43, comprising: introducing the hollow-core photonic crystal fiber into the sleeve device; and

[0195] The sleeve is locally heated to collapse it onto the hollow photonic crystal fiber.

[0196] 45. The method according to Clause 44, wherein the step of local heating comprises: adjusting the heating intensity and heating time during the step until a strong mechanical connection is achieved so as to minimize the twist of the hollow photonic crystal fiber.

[0197] 46. ​​A broadband light source device configured to generate broadband output, comprising:

[0198] The optical component according to any one of clauses 32 to 43; and

[0199] The mounting device clamps the optical component onto the sleeve device.

[0200] 47. The broadband light source apparatus according to Clause 46 further includes a pump laser for outputting multiple pump pulses to excite a gas medium housed within a hollow photonic crystal fiber for supercontinuum generation.

[0201] 48. The broadband light source device according to clause 46 or 47, wherein the broadband output includes a wavelength range of 230 nm to 2300 nm, or a subrange within that range.

[0202] 49. A measuring device comprising a broadband light source device according to any one of clauses 20 to 22 or 46 to 48.

[0203] 50. The measuring device according to clause 49, wherein the measuring device is operable as a scattering measuring device.

[0204] 51. The measuring device according to Clause 49, wherein the measuring device is capable of operating as a level sensor or an alignment sensor.

[0205] 52. A lithography apparatus comprising at least one of the measurement devices described in Clause 51, the at least one of the measurement devices being used to perform alignment and / or leveling measurements.

[0206] 53. A lithography unit comprising the lithography apparatus according to Clause 52 and the measurement device according to Clause 50.

[0207] 54. An optical component, comprising:

[0208] Hollow-core photonic crystal fiber;

[0209] The first and second transparent end caps seal the corresponding ends of the hollow-core photonic crystal fiber.

[0210] An end section between each end of a hollow photonic crystal fiber and its corresponding end cap, the end section comprising, at least a portion of the end section, an inner diameter larger than the inner diameter of the hollow photonic crystal fiber; and

[0211] The gaseous medium is sealed within a space defined by the hollow photonic crystal fiber, the end section, and the end cap.

[0212] 55. The optical component according to Clause 54, wherein one or both end sections are tapered end sections that taper outward to define an inner diameter extending from the hollow photonic crystal fiber toward the corresponding end cap.

[0213] 56. The optical component according to Clause 54, wherein one or both end sections have a substantially uniform inner diameter between the hollow-core photonic crystal fiber and the corresponding end cap.

[0214] 57. The optical component according to clauses 54, 55 or 56, wherein the end section is configured such that divergent broadband radiation emitted from the hollow-core photonic crystal fiber and / or converging pump radiation allowed to enter the hollow-core photonic crystal fiber are not blocked by the corresponding end section in the axial propagation direction.

[0215] 58. The optical component according to any one of clauses 54 to 57, wherein the first transparent end cap is configured to receive a pump radiation beam to excite the gas medium for supercontinuum generation, and the second transparent end cap is configured to emit an output beam from the supercontinuum generation.

[0216] 59. The optical component according to Clause 58, wherein the first transparent end cap includes an input lens for coupling into the pump radiation beam and / or the second transparent end cap includes an output lens for collimating the output beam.

[0217] 60. The optical component according to any one of clauses 54 to 59, wherein the internal capillaries of the hollow photonic crystal fiber are collapsed to define a tapered core region at each end of the hollow photonic crystal fiber, the tapered core region including a region in which the diameter of the hollow core of the hollow photonic crystal fiber increases toward each end of the hollow photonic crystal fiber.

[0218] 61. The optical component according to any one of clauses 54 to 60, wherein the hollow-core photonic crystal fiber includes an fiber coating.

[0219] 62. The optical component according to clause 61, wherein the fiber coating comprises a polymer.

[0220] 63. The optical component according to any one of clauses 54 to 62, wherein the end section and / or end cap is composed of silicon dioxide or borosilicate.

[0221] 64. A broadband light source device configured to generate broadband output, comprising:

[0222] The optical component according to any one of clauses 54 to 63; and

[0223] The mounting device clamps the optical component at one or more points on the end section.

[0224] 65. The broadband light source apparatus according to Clause 64 further includes a pump laser for outputting a plurality of pump pulses to excite the gas medium for supercontinuum generation.

[0225] 66. The broadband light source device according to clause 64 or 65, wherein the broadband output includes a wavelength range of 200 nm to 2000 nm, or a subrange within that range.

[0226] 67. A method of manufacturing an optical component as described in any one of clauses 54 to 63, comprising:

[0227] Each end segment is spliced ​​to the corresponding end of the hollow-core photonic crystal fiber, and each end segment is attached with a corresponding end cap; and

[0228] The optical component is filled using the gaseous medium.

[0229] 68. The method according to Clause 67, wherein the filling of the gaseous medium is performed before the final splicing of the splicing step is performed.

[0230] 69. The method described under Clause 68, comprising:

[0231] Prior to the final assembly, the optical components are inserted into the evacuated container;

[0232] Optical components are flushed with pressurized gas; and

[0233] The final assembly is carried out in a high-pressure environment.

[0234] 70. The method according to Clause 69, wherein the rinsing step comprises: heating the hollow photonic crystal fiber while removing the nozzle used in the rinsing step.

[0235] While specific references are made to the use of lithography equipment in IC manufacturing in this article, it should be understood that the lithography equipment described herein can have other applications. Possible other applications include the fabrication of integrated optical systems, patterning for guiding and detecting magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, etc.

[0236] Although embodiments of the invention may be specifically referred to herein in the context of lithography equipment, embodiments of the invention can be used in other equipment. Embodiments of the invention can form part of any equipment that forms a mask inspection apparatus, a metrology apparatus, or an apparatus that measures or processes objects such as wafers (or other substrates) or masks (or other patterning apparatuses). These apparatuses are commonly referred to as lithography tools. Such lithography tools can use vacuum conditions or ambient (non-vacuum) conditions.

[0237] Although specific reference has been made above to the use of embodiments of the invention in the context of optical lithography, it should be understood that, where the context permits, the invention is not limited to optical lithography and can be used in other applications, such as imprint lithography.

[0238] While specific embodiments of the invention 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 illustrate and not limit. 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 following claims.

Claims

1. An optical component, comprising: Hollow-core photonic crystal fiber includes an internal capillary for guiding radiation and an external capillary covering the internal capillary; At least one output section, the inner diameter of at least a portion of the output section is greater than the inner diameter of the outer capillary along the central portion of the hollow photonic crystal fiber before the output section. Input segment; First transparent end cap and second transparent end cap The input section is included between the input end of the hollow-core photonic crystal fiber and the first transparent end cap, and the output section is included between the output end of the hollow-core photonic crystal fiber and the second transparent end cap. During the splicing of the output end of the hollow photonic crystal fiber with the external capillary, the internal capillary of the hollow photonic crystal fiber collapses at the end of the hollow photonic crystal fiber, such that the cross-sectional size of the capillary decreases and the cross-sectional size of the hollow region increases along the direction toward the end.

2. The optical component according to claim 1, wherein the output section is configured such that the divergent broadband radiation emitted from the hollow photonic crystal fiber is not blocked by the output section in the axial propagation direction.

3. The optical component according to claim 1 or 2, wherein the internal capillary of the hollow photonic crystal fiber is collapsed to define a tapered core region at each end of the hollow photonic crystal fiber, the tapered core region including a region in which the hollow core of the hollow photonic crystal fiber has a diameter that increases toward each end of the hollow photonic crystal fiber.

4. The optical component according to claim 1, wherein the first transparent end cap and the second transparent end cap seal the respective ends of the hollow photonic crystal fiber, and the optical component further comprises: The gaseous medium is sealed within a space defined by the hollow photonic crystal fiber, the end section, and the end cap.

5. The optical component of claim 4, wherein the input section is configured such that the converging pump radiation allowed to enter the hollow photonic crystal fiber is not blocked by the input section in the axial propagation direction.

6. The optical component of claim 1, wherein one or both end sections are tapered end sections, the tapered end sections being tapered outward to define an expansion inner diameter from the hollow photonic crystal fiber toward the corresponding end cap.

7. The optical component according to claim 1, wherein one or both end sections have a substantially uniform inner diameter between the hollow photonic crystal fiber and the corresponding end cap.

8. The optical component of claim 4, wherein the first transparent end cap is configured to receive a pump radiation beam to excite the gas medium for supercontinuum generation, and the second transparent end cap is configured to emit an output beam generated from the supercontinuum.

9. The optical component of claim 8, wherein the first transparent end cap includes an input lens for coupling into the pump radiation beam and / or the second transparent end cap includes an output lens for collimating the output beam.

10. The optical component according to claim 1, wherein the end cap is composed of silicon dioxide or borosilicate.

11. The optical component of claim 1, wherein the output end section is widened outward to define an expanded inner diameter from the hollow photonic crystal fiber toward the output end of the output end section.

12. The optical component of claim 11, wherein the output section includes at least a widened output portion of the external capillary.

13. The optical component of claim 12, wherein the internal capillary of the hollow photonic crystal fiber is formed away from the longitudinal axis of the optical component at the output end section.

14. The optical component of claim 13, wherein the internal capillary is mixed into the external capillary at the output section.

15. The optical component of claim 11, wherein the output section includes an end section spliced ​​to the end of the hollow-core photonic crystal fiber.

16. The optical component of claim 11, wherein the inner diameter of the output section at its widest point is any value in the range of 100 μm to 4.5 mm.

17. The optical component of claim 1, wherein the hollow photonic crystal fiber comprises an optical fiber coating.

18. The optical component of claim 17, wherein the fiber coating comprises a polymer.

19. The optical component of claim 1, wherein at least the output section is composed of silicon dioxide or borosilicate.

20. A broadband light source device configured to generate a broadband output, comprising: The optical component according to any one of the preceding claims; as well as The mounting device clamps the optical component at one or more points on the end section.

21. The broadband light source device according to claim 20 further includes a pump laser for outputting a plurality of pump pulses to excite a gas medium for supercontinuum generation.

22. The broadband light source device according to claim 20 or 21, wherein the broadband output includes a wavelength range of 200 nm to 2000 nm.

23. A method for manufacturing an optical component according to any one of claims 1 to 10, comprising: Each end segment in the end section is spliced ​​to the corresponding end of the hollow photonic crystal fiber, and each end segment is attached with a corresponding end cap. as well as The optical component is filled with a gaseous medium.

24. The method of claim 23, wherein the filling of the gas medium is performed before the final splicing of the splice is performed.

25. The method of claim 24, comprising: Prior to the final assembly, the optical components are inserted into the evacuated container; The optical components are rinsed using pressurized gas; as well as The final assembly is manufactured in a high-pressure environment.

26. The method of claim 25, wherein the rinsing comprises: The hollow photonic crystal fiber is heated while the nozzle used in the rinsing is removed.

27. A method for manufacturing an optical component according to any one of claims 12 to 14, comprising: A pressure difference is established between the inner region and the outer region of the hollow photonic crystal fiber, while heat is locally applied to the hollow photonic crystal fiber to cause it to expand in the region where the heat is applied.

28. The method of claim 27, comprising: The output end of the hollow-core photonic crystal fiber is initially cleaved; and The pressure difference is established by placing a counterbalance near the output end of the hollow photonic crystal fiber to prevent flow from the output end and introducing fluid at the input end of the hollow photonic crystal fiber.

29. The method of claim 27, comprising: The pressure difference is established to form bubbles along the length of the hollow photonic crystal fiber in the region where heat is locally applied; as well as The output end of the hollow photonic crystal fiber is split at the bubble.

30. A method for manufacturing the optical component of claim 15, comprising: A heat source is locally applied to the capillary optical fiber, while tension is applied from both ends of the fiber to create a tapered shape; The optical fiber is split at the tapered section to create the output segment; as well as The output section is spliced ​​to the output end of the hollow-core photonic crystal fiber.

31. A method for manufacturing the optical component of claim 15, comprising: The output section is formed in the drawing tower; as well as The output section is spliced ​​to the output end of the hollow-core photonic crystal fiber.

32. An optical component, comprising: Hollow-core photonic crystal fiber includes an internal capillary for guiding radiation and an external capillary covering the internal capillary; A first transparent end cap and a second transparent end cap seal the corresponding ends of the hollow-core photonic crystal fiber. An end section is located between each end of the hollow-core photonic crystal fiber and its corresponding end cap, and on at least a portion of the end section, the inner diameter of the end section is larger than the inner diameter of the hollow-core photonic crystal fiber. as well as The gaseous medium is sealed within a space defined by the hollow-core photonic crystal fiber, the end section, and the end cap. The input section is included between the input end of the hollow-core photonic crystal fiber and the first transparent end cap, and the output section is included between the output end of the hollow-core photonic crystal fiber and the second transparent end cap. During the splicing of the output end of the hollow photonic crystal fiber with the external capillary, the internal capillary of the hollow photonic crystal fiber collapses at the end of the hollow photonic crystal fiber, such that the cross-sectional size of the capillary decreases and the cross-sectional size of the hollow region increases along the direction toward the end.

33. The optical component of claim 32, wherein one or both end sections are tapered end sections, the tapered end sections being tapered outward to define an inner diameter extending from the hollow photonic crystal fiber toward the corresponding end cap.

34. The optical component of claim 32, wherein one or both end sections have a substantially uniform inner diameter between the hollow photonic crystal fiber and the corresponding end cap.

35. The optical component according to claim 32, 33 or 34, wherein the end section is configured such that divergent broadband radiation emitted from the hollow photonic crystal fiber and / or converging pump radiation allowed to enter the hollow photonic crystal fiber are not blocked by the corresponding end section in the axial propagation direction.

36. The optical component of claim 32, wherein the first transparent end cap is configured to receive a pump radiation beam to excite the gas medium for supercontinuum generation, and the second transparent end cap is configured to emit an output beam generated from the supercontinuum.

37. The optical component of claim 36, wherein the first transparent end cap includes an input lens for coupling into the pump radiation beam and / or the second transparent end cap includes an output lens for collimating the output beam.

38. The optical component of claim 32, wherein the internal capillaries of the hollow photonic crystal fiber are collapsed to define a tapered core region at each end of the hollow photonic crystal fiber, the tapered core region including a region in which the diameter of the hollow core of the hollow photonic crystal fiber increases toward each end of the hollow photonic crystal fiber.

39. The optical component of claim 32, wherein the hollow photonic crystal fiber comprises an optical fiber coating.

40. The optical component of claim 39, wherein the fiber coating comprises a polymer.

41. The optical component of claim 32, wherein the end section and / or the end cap is composed of silicon dioxide or borosilicate.

42. A broadband light source device configured to generate broadband output, comprising: The optical component according to any one of claims 32 to 41; as well as The mounting device clamps the optical component at one or more points on the end section.

43. The broadband light source device according to claim 42 further includes a pump laser for outputting a plurality of pump pulses to excite the gas medium for supercontinuum generation.

44. The broadband light source device according to claim 42 or 43, wherein the broadband output includes a wavelength range of 200 nm to 2000 nm.

45. A method for manufacturing an optical component according to any one of claims 32 to 41, comprising: Each end segment in the end section is spliced ​​to the corresponding end of the hollow photonic crystal fiber, and each end segment is attached with a corresponding end cap. as well as The optical component is filled with the gaseous medium.

46. ​​The method of claim 45, wherein the filling of the gas medium is performed before the final splicing of the splice is performed.

47. The method of claim 46, comprising: Prior to the final assembly, the optical components are inserted into the evacuated container; The optical components are flushed with pressurized gas; as well as The final assembly is performed in a high-pressure environment.

48. The method of claim 47, wherein the rinsing comprises: The hollow photonic crystal fiber is heated while the nozzle used in the rinsing step is removed.

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