Lithographic equipment, measurement system, irradiation source and method thereof

Abstract

A system includes an illumination system, an optical element, and a detector. The optical system is applied on a substrate. The illumination system includes a first source and a second source and a first generator and a second generator. The illumination system generates a radiation beam. The first source and the second source generate respective different first and second wavelength bands. The first resonator and the second resonator are optically coupled to respective ones of the first source and the second source and narrow the respective wavelength bands in the first and second wavelength bands. The optical element directs the beam toward a target structure. The detector receives radiation from the target structure and generates a measurement signal based on the received radiation.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 954,836, filed on December 30, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to metrology systems with integrated optics, for example, illumination systems with integrated photonic devices in metrology systems for checking lithography processes and wafer alignment. Background Art

[0004] A lithographic apparatus is a machine that applies a desired pattern to a substrate, usually to a target portion of the substrate. A lithographic apparatus can be used, for example, to manufacture an integrated circuit (IC). In this case, a pattern forming device, alternatively referred to as a mask or reticle, can be used to generate a circuit pattern to be formed on a separate layer of the IC. The pattern can be transferred to a target portion (e.g., including a portion of a die, one or several dies) on a substrate (e.g., a silicon wafer). The transfer of the pattern is usually achieved by imaging a layer of radiation-sensitive material (resist) provided on the substrate. Typically, a single substrate will contain a grid of adjacent target portions that are patterned continuously. Known lithographic apparatus include: a so-called stepper, in which each target portion is irradiated by exposing the entire pattern to the target portion at once; and a so-called scanner, in which each target portion is irradiated by scanning the target portion synchronously parallel or antiparallel to the scanning direction while scanning the pattern with a radiation beam in a given direction (the "scanning" direction). The pattern can also be transferred from the pattern forming device to the substrate by printing the pattern onto the substrate.

[0005] Another type of lithography system is an interferometric lithography system, in which there is no patterning device, but rather the light beam is split into two beams and the two beams are caused to interfere at a target portion of the substrate using a reflection system. The interference results in the formation of a line at the target portion of the substrate.

[0006] During a lithography operation, different processing steps may require different layers to be formed sequentially on a substrate. Therefore, it may be necessary to position the substrate with high precision relative to a previous pattern formed on the substrate. Typically, alignment marks are placed on the substrate to be aligned and positioned with reference to a second object. The lithography equipment may use an alignment device to detect the position of the alignment marks and align the substrate using the alignment marks to ensure accurate exposure from the mask. The misalignment between alignment marks at two different layers is measured as overlay error.

[0007] In order to monitor the lithography process, the parameters of the patterned substrate are measured. The parameters may include, for example, the overlay error between successive layers formed in or on the patterned substrate and the critical line width of the developed photoresist. The measurement may be performed on a product substrate and / or a dedicated measurement target. There are a variety of techniques for measuring the microstructures formed in the lithography process, including the use of scanning electron microscopes and various dedicated tools. A fast and non-invasive form of dedicated inspection tool is a scatterometer, in which a radiation beam is directed onto a target on the surface of the substrate and the characteristics of the scattered or reflected beam are measured. By comparing the characteristics of the beam before and after being reflected or scattered by the substrate, the characteristics of the substrate can be determined. This can be done, for example, by comparing the reflected beam with data stored in a known measurement library associated with known substrate characteristics. A spectral scatterometer directs a broadband radiation beam onto a substrate and measures the spectrum (intensity as a function of wavelength) of the radiation scattered into a specific narrow angular range. In contrast, an angularly resolved scatterometer uses a monochromatic radiation beam and measures the intensity of the scattered radiation as a function of angle.

[0008] Such optical scatterometers can be used to measure parameters such as the critical dimension of a developed photoresist or the overlay error (OV) between two layers formed in or on a patterned substrate. Properties of a substrate can be determined by comparing the properties of a radiation beam before and after the radiation beam has been reflected or scattered by the substrate.

[0009] As ICs become smaller and more densely packed, the number of features that must be inspected per wafer increases. Increased metrology system capabilities are needed to keep pace with current high-volume manufacturing rates and to increase production speeds beyond what is currently available. Summary of the invention

[0010] Therefore, it is desirable to provide a metrology tool that can quickly and accurately measure a large number of lithographic features.Metrology schemes may include, for example, increasing the number of simultaneous measurements and / or increasing the speed of measurement.

[0011] In some embodiments, the system includes an illumination system, an optical element, and a detector. The optical system is applied on a substrate. The illumination system includes a first source and a second source and a first generator and a second generator. The illumination system is configured to generate a radiation beam. The first source and the second source are configured to generate corresponding different first wavelength bands and second wavelength bands. The first resonator and the second resonator are optically coupled to the corresponding source of the first source and the second source, and are configured to narrow the corresponding wavelength bands in the first wavelength band and the second wavelength band. The optical element is configured to direct the beam toward the target structure. The detector is configured to receive radiation returned from the target structure and generate a measurement signal based on the received radiation.

[0012] In some embodiments, a lithography device includes an irradiation device, a projection system, and a measurement system. The measurement system includes an irradiation system, an optical element, and a detector. The optical system is applied on a substrate. The irradiation system includes a first source and a second source and a first generator and a second generator. The irradiation device is configured to irradiate a pattern of a pattern forming device. The projection system is configured to project an image of the pattern onto a target substrate. The irradiation system is configured to generate a radiation beam. The first source and the second source are configured to generate corresponding different first wavelength bands and second wavelength bands. The first resonator and the second resonator are optically connected to the corresponding source of the first source and the second source, and are configured to narrow the corresponding wavelength bands in the first wavelength band and the second wavelength band. The optical element is configured to direct the beam toward a target structure. The detector is configured to receive radiation from the target structure and generate a measurement signal based on the received radiation

[0013] In some embodiments, a method includes generating a radiation beam using an illumination system on a substrate, the illumination system including first and second sources and corresponding first and second resonators. The method also includes generating a first wavelength band of the beam using the first source, generating a second wavelength band of the beam different from the first wavelength band using the second source, narrowing the first wavelength band using the first resonator, narrowing the second wavelength band using the second resonator, directing the beam toward a target structure, receiving radiation from the target structure using a detector, and generating a measurement signal based on the received radiation using the detector.

[0014] The further features of the present disclosure and the structure and operation of various embodiments are described in detail below with reference to the accompanying drawings. Note that the present disclosure is not limited to the specific embodiments described herein. These embodiments are presented herein only for illustrative purposes. Based on the teachings contained herein, other embodiments will be apparent to those skilled in the relevant art. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and enable one skilled in the relevant art to make and use the embodiments described herein.

[0016] Figure 1A A schematic diagram of a reflective lithography apparatus according to some embodiments is shown.

[0017] Figure 1B A schematic diagram of a transmissive lithography apparatus according to some embodiments is shown.

[0018] Figure 2 A more detailed schematic diagram of a reflective lithography apparatus according to some embodiments is shown.

[0019] Figure 3 A schematic diagram of a lithography cell is shown in accordance with some embodiments.

[0020] Figure 4A and Figure 4B A schematic diagram of an alignment apparatus according to some embodiments is shown.

[0021] Figure 5 A schematic diagram of a metrology system according to some embodiments is shown.

[0022] Figure 6 A schematic diagram of an illumination system according to some embodiments is shown.

[0023] Figure 7 A schematic diagram of a ring resonator is shown in accordance with some embodiments.

[0024] Figure 8 A schematic diagram of a spectrum generated by an illumination system is shown according to some embodiments.

[0025] Fig. 9 Method steps according to some embodiments are shown for performing the functions of the embodiments described herein.

[0026] Features of the present disclosure will become more apparent in the following detailed description in conjunction with the accompanying drawings, in which like reference numerals identify corresponding elements throughout. In the accompanying drawings, like reference numerals generally represent identical, functionally similar, and / or structurally similar elements. In addition, typically, the leftmost digit or digits of a reference numeral identify the drawing in which the reference numeral first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be construed as drawings drawn to scale. DETAILED DESCRIPTION

[0027] This specification discloses one or more embodiments incorporating features of the present disclosure. The disclosed one or more embodiments are provided as examples. The scope of the present disclosure is not limited to the disclosed one or more embodiments. The features claimed for protection are defined by the accompanying claims.

[0028] The one or more embodiments described and references in the specification to "one embodiment," "an embodiment," "an exemplary embodiment," etc. indicate that the one or more embodiments described may include a particular feature, structure, or characteristic, but each embodiment may not necessarily include the particular feature, structure, or characteristic. Furthermore, these phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, whether or not explicitly described, it should be understood that such feature, structure, or characteristic may be implemented in conjunction with other embodiments within the knowledge of those skilled in the art.

[0029] For ease of description, spatially relative terms such as "below," "beneath," "lower," "above," "upper," and the like may be used herein to describe the relationship of one element or feature to another element or features illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0030] As used herein, the term "substantially" refers to a value of a given quantity that may vary based on a particular technology. Based on a particular technology, the term "substantially" may refer to a value that varies within a range of, for example, 10% to 30% of a given quantity (e.g., ±10%, ±20%, or ±30% of the value).

[0031] The embodiments of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. The embodiments of the present disclosure may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include: a read-only memory (ROM); a random access memory (RAM); a disk storage medium; an optical storage medium; a flash memory device; an electrical, optical, acoustic, or other form of propagation signal (e.g., a carrier wave, an infrared signal, a digital signal, etc.), etc. In addition, firmware, software, routines, and / or instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are only for convenience, and that these actions are actually generated by a computing device, processor, controller, or other device that executes firmware, software, routines, instructions, etc.

[0032] However, before describing such embodiments in further detail, it is helpful to present an example environment in which embodiments of the present disclosure may be implemented.

[0033] Exemplary Lithography System

[0034] Figure 1A and Figure 1BSchematic diagrams of a lithographic apparatus 100 and a lithographic apparatus 100' in which embodiments of the present disclosure may be implemented are shown, respectively. The lithographic apparatus 100 and the lithographic apparatus 100' respectively include the following items: an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., deep ultraviolet or extreme ultraviolet radiation); a support structure (e.g., a mask stage) MT configured to support a pattern forming device (e.g., a mask, a reticle, or a dynamic pattern forming device) MA and connected to a first positioner PM configured to accurately position the pattern forming device MA; and a substrate stage (e.g., a wafer stage) WT configured to hold a substrate (e.g., a wafer coated with a resist) W and connected to a second positioner PW configured to accurately position the substrate W. The lithographic apparatus 100 and 100' further has a projection system PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion (e.g., comprising one or more dies) C of the substrate W. In the lithographic apparatus 100, the patterning device MA and the projection system PS are reflective. In the lithographic apparatus 100', the patterning device MA and the projection system PS are transmissive.

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

[0036] The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA relative to the reference frame, the design of at least one of the lithographic apparatuses 100 and 100', and other conditions, such as whether the patterning device MA is held in a vacuum environment. The support structure MT may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device MA. The support structure MT may be, for example, a frame or table that may be fixed or movable as desired. By using sensors, the support structure MT may ensure that the patterning device MA is in a desired position, for example relative to the projection system PS.

[0037] The term “patterning device” MA should be broadly interpreted as referring to any device that can be used to impart a pattern to the radiation beam B in its cross-section so as to create a pattern in a target portion C of the substrate W. The pattern imparted to the radiation beam B may correspond to a specific functional layer in a device being created in the target portion C to form an integrated circuit.

[0038] The pattern forming device MA can be a transmissive type (such as in Figure 1B lithographic apparatus 100') or a reflective type (such as in Figure 1A100). Examples of pattern forming devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks are well known in lithography and include mask types such as binary, alternating phase shift, or attenuated phase shift, as well as various hybrid mask types. Examples of programmable mirror arrays employ a matrix arrangement of smaller mirrors, each of which can be individually tilted to reflect an incoming radiation beam in different directions. The tilted mirrors produce a pattern in a radiation beam B that is reflected by the matrix of smaller mirrors.

[0039] The term "projection system" PS may cover any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, depending on the exposure radiation used or other factors, such as the use of an immersion liquid on the substrate W or the use of a vacuum. A vacuum environment may be used for EUV or electron beam radiation, as other gases may absorb too much radiation or electrons. Therefore, a vacuum environment may be provided for the entire beam path with the aid of vacuum walls and a vacuum pump.

[0040] The lithographic apparatus 100 and / or lithographic apparatus 100' may be of a type having two (dual stage) or more substrate tables WT (and / or two or more mask tables). In such a "multi-stage" machine, the additional substrate tables WT may be used in parallel, or preparatory steps may be performed on one or more tables while one or more other substrate tables WT are being used for exposure. In some cases, the additional tables may not be substrate tables WT.

[0041] The lithographic apparatus may also be of a type in which at least a portion of the substrate may be covered by a liquid having a relatively high refractive index (e.g., water) to fill the space between the projection system and the substrate. Immersion liquid may also be applied to other spaces in the lithographic apparatus, such as between the mask and the projection system. Immersion techniques for increasing the numerical aperture of the projection system are well known in the art. As used herein, the term "immersion" does not mean that structures such as the substrate are necessarily immersed in the liquid, but only means that the liquid is located between the projection system and the substrate during exposure.

[0042] refer to Figure 1A and Figure 1B , the illuminator IL receives a radiation beam from a radiation source SO. For example, when the source SO is an excimer laser, the source SO and the lithographic apparatus 100, 100' may be separate physical entities. In this case, the source SO is not considered to form part of the lithographic apparatus 100 or 100', and the radiation beam B is delivered to the lithographic apparatus 100 or 100' by the beam delivery system BD (in Figure 1BThe beam is transferred from the source SO to the illuminator IL with the help of a beam delivery system (e.g., a suitable directional reflector and / or a beam expander). In other cases, for example, when the source SO is a mercury lamp, the source SO may be an integral part of the lithographic apparatus 100, 100'. If desired, the source SO and the illuminator IL and the beam delivery system BD may be referred to as a radiation system.

[0043] The illuminator IL may comprise an adjuster AD (at Figure 1B In general, at least the outer and / or inner radial extent (commonly referred to as "σ-outer" and "σ-inner", respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. Furthermore, the illuminator IL may include various other components (in Figure 1B In the embodiment of the present invention, for example, an integrator IN and a condenser CO. The illuminator IL can be used to condition the radiation beam B so that it has a desired uniformity and intensity distribution in its cross-section.

[0044] refer to Figure 1A , the radiation beam B is incident on a patterning device (e.g., a mask) MA, which is held on a support structure (e.g., a mask table) MT, and is patterned by the patterning device MA. In the lithographic apparatus 100, the radiation beam B is reflected from the patterning device (e.g., a mask) MA. After the radiation beam B is reflected from the patterning device (e.g., a mask) MA, the radiation beam B passes through a projection system PS, which focuses the radiation beam B onto a target portion C of a substrate W. With the help of a second positioner PW and a position sensor IF2 (e.g., an interferometer, a linear encoder, or a capacitive sensor), the substrate table WT can be accurately moved (e.g., so as to position a different target portion C in the path of the radiation beam B). Similarly, a first positioner PM and a further position sensor IF1 can be used to accurately position the patterning device (e.g., a mask) MA relative to the path of the radiation beam B. The patterning device (e.g., a mask) MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2.

[0045] refer to Figure 1B , the radiation beam B is incident on a patterning device (e.g., mask MA), which is held on a support structure (e.g., mask table MT), and is patterned by the patterning device. After passing through the mask MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of a substrate W. The projection system has a conjugate pupil PPU that is conjugate to an illumination system pupil IPU. Multiple portions of the radiation emanate from the intensity distribution at the illumination system pupil IPU and pass through the mask pattern without being affected by diffraction at the mask pattern, and create an image of the intensity distribution at the illumination system pupil IPU.

[0046] The projection system PS projects an image MP' of a mask pattern MP onto a photoresist layer coated on a substrate W, wherein the image MP' is formed by a diffraction beam generated from the marking pattern MP by radiation from an intensity distribution. For example, the mask pattern MP may include an array of lines and spaces. The diffraction of the radiation at the array is different from the zero-order diffraction, generating a deflected diffraction beam, the direction of which changes in a direction perpendicular to the line. The undiffracted beam (i.e., the so-called zero-order diffraction beam) passes through the pattern in the propagation direction without any change. The zero-order diffraction beam passes through the upper lens or upper lens group of the projection system PS upstream of the pupil conjugate PPU of the projection system PS to reach the conjugate pupil PPU. The portion of the intensity distribution in the plane of the conjugate pupil PPU and associated with the zero-order diffraction beam is an image of the intensity distribution in the illumination system pupil IPU of the illumination system IL. For example, the aperture device PD is arranged or substantially arranged at a plane including the conjugate pupil PPU of the projection system PS.

[0047] The projection system PS is arranged to capture not only the zero-order diffraction beam, but also the first-order or first-order and higher-order diffraction beams (not shown) through a lens or lens group L. In some embodiments, dipole illumination for imaging a line pattern extending in a direction perpendicular to the line can be used to exploit the resolution enhancement effect of dipole illumination. For example, the first-order diffraction beam interferes with the corresponding zero-order diffraction beam at the horizontal plane of the wafer W to create an image of the line pattern MP at the highest possible resolution and process window (i.e., the available depth of focus combined with the tolerable exposure dose deviation). In some embodiments, astigmatic aberrations can be reduced by providing a radiation pole (not shown) in the opposite quadrant of the illumination system pupil IPU. In addition, in some embodiments, astigmatic aberrations can be reduced by blocking the zero-order beam associated with the radiation pole in the opposite quadrant in the conjugate pupil PPU of the projection system. This is described in more detail in US 7,511,799 B2 published on March 31, 2009, which is incorporated herein by reference in its entirety.

[0048] With the aid of a second positioner PW and a position sensor IF (e.g. an interferometer, a linear encoder or a capacitive sensor), the substrate table WT can be accurately moved (e.g. in order to position a different target portion C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor ( Figure 1B ) can be used to accurately position the mask MA relative to the path of the radiation beam B (for example, after mechanical retrieval from a mask library or during scanning).

[0049] Typically, movement of the mask table MT can be achieved with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning) which form part of the first positioner PM. Similarly, movement of the substrate table WT can be achieved using a long-stroke module and a short-stroke module which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask table MT may be connected only to a short-stroke actuator or may be fixed. The mask MA and the substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the substrate alignment marks (as shown) occupy dedicated target portions, they may be located in the space between target portions (referred to as scribe alignment marks). Similarly, where more than one die is provided on the mask MA, the mask alignment marks may be located between the dies.

[0050] The mask table MT and the patterning device MA may be in the vacuum chamber V, where a vacuum robot IVR may be used to move the patterning device, such as a mask, into and out of the vacuum chamber. Alternatively, when the mask table MT and the patterning device MA are outside the vacuum chamber, an out-of-vacuum robot may be used for various transport operations, similar to the in-vacuum robot IVR. Both the in-vacuum robot and the out-of-vacuum robot need to be calibrated in order to smoothly transfer any payload (e.g., a mask) to the fixed kinematic support of the transfer station.

[0051] The lithographic apparatus 100 and 100' may be used in at least one of the following modes:

[0052] 1. In step mode, the support structure (e.g. mask table) MT and the substrate table WT remain substantially stationary while the entire pattern imparted to the radiation beam B is projected at once onto a target portion C (i.e. a single static exposure). The substrate table WT is then moved in the X and / or Y direction so that a different target portion C can be exposed.

[0053] 2. In scan mode, the support structure (e.g. mask table) MT and substrate table WT are scanned synchronously while a pattern imparted to the radiation beam B is projected onto a target portion C (i.e. single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure (e.g. mask table) MT may be determined by the (de-)magnification and image reversal characteristics of the projection system PS.

[0054] 3. In another mode, the support structure (e.g., mask table) MT is kept substantially stationary to hold the programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C. A pulsed radiation source SO may be used, and the programmable patterning device is updated as required after each movement of the substrate table WT or between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography utilizing a programmable patterning device (e.g., a programmable mirror array).

[0055] Combinations and / or variations of the described modes of use or entirely different modes of use may also be employed.

[0056] In a further embodiment, the lithographic apparatus 100 comprises an extreme ultraviolet (EUV) source configured to generate an EUV radiation beam for EUV lithography. Typically, the EUV source is configured in a radiation system, and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

[0057] Figure 2 The lithographic apparatus 100 is shown in more detail and includes a source collector device SO, an illumination system IL and a projection system PS. The source collector device SO is constructed and arranged so that a vacuum environment can be maintained in an enclosure 220 of the source collector device SO. An EUV radiation emitting plasma 210 can be formed by a plasma source generated by a discharge. EUV radiation can be generated by a gas or vapor, such as xenon, lithium vapor or tin vapor, in which a very hot plasma 210 is generated to emit radiation in the EUV range of the electromagnetic spectrum. The very hot plasma 210 is generated by, for example, a discharge that causes an at least partially ionized plasma. A partial pressure of, for example, 10 Pa of Xe, Li, Sn vapor or any other suitable gas or vapor may be required to effectively generate radiation. In some embodiments, an excited tin (Sn) plasma is provided to generate EUV radiation.

[0058] The radiation emitted by the hot plasma 210 passes from the source chamber 211 into the collection chamber 212 through an optional gas barrier or contaminant trap 230 (also referred to as a contaminant barrier or foil trap in some cases) located in or behind an opening in the source chamber 211. The contaminant trap 230 may include a channel structure. The contaminant trap 230 may also include a gas barrier or a combination of a gas barrier and a channel structure. The contaminant trap or contaminant barrier 230 further noted herein includes at least a channel structure.

[0059] The collector chamber 212 may include a radiation collector CO, which may be a so-called grazing incidence collector. The radiation collector CO has an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation passing through the collector CO may be reflected by a grating spectral filter 240 to be focused in a virtual source point IF. The virtual source point IF is often referred to as an intermediate focus, and the source collector device is arranged so that the intermediate focus IF is located at or near an opening 219 in the enclosure structure 220. The virtual source point IF is an image of the radiation emitting plasma 210. The grating spectral filter 240 is particularly useful for suppressing infrared (IR) radiation.

[0060] The radiation then passes through an illumination system IL which may include a faceted field mirror arrangement 222 and a faceted pupil mirror arrangement 224 arranged to provide a desired angular distribution of the radiation beam 221 at the patterning device MA and a desired uniformity of the radiation intensity at the patterning device MA. When the radiation beam 221 is reflected at the patterning device MA held by the support structure MT, a patterned beam 226 is formed and the patterned beam 226 is imaged by the projection system PS via reflective elements 228, 229 onto a substrate W held by a wafer stage or substrate table WT.

[0061] There may typically be more elements than shown in the illumination optics unit IL and the projection system PS. Depending on the type of lithographic apparatus, a grating spectral filter 240 may optionally be present. In addition, there may be more than Figure 2 For example, there may be more than 10 mirrors in the projection system PS. Figure 2 The reflective elements shown range from one to six additional reflective elements.

[0062] like Figure 2 As shown, the collector optics CO is depicted as a nested collector with grazing incidence reflectors 253, 254 and 255, merely as an example of a collector (or collector mirror). The grazing incidence reflectors 253, 254 and 255 are arranged axisymmetrically around the optical axis O, and this type of collector optics CO is preferably used in conjunction with a discharge produced plasma source, commonly referred to as a DPP source.

[0063] Exemplary Lithography Cell

[0064] Figure 3A lithography unit 300 is shown according to some embodiments, which is sometimes also referred to as a lithocell or cluster. The lithography apparatus 100 or 100' may form part of the lithography unit 300. The lithography unit 300 may also include one or more devices to perform pre-exposure and post-exposure processes on the substrate. Typically these include a spin coater SC for depositing a resist layer, a developer DE for developing the exposed resist, a chill plate CH and a bake plate BK. A substrate handler or robot RO picks up substrates from input / output ports I / O1, I / O2, moves substrates between different processing devices and transfers substrates to a feed station LB of the lithography apparatus 100 or 100'. These devices, which are generally collectively referred to as tracks, are under the control of a track control unit TCU, which itself is controlled by a monitoring system SCS, which also controls the lithography apparatus via a lithography control unit LACU. Thus, different devices may be operated to maximize throughput and processing efficiency.

[0065] Exemplary Inspection Equipment

[0066] In order to control the lithography process to accurately place device features on the substrate, alignment marks are usually provided on the substrate, and the lithography equipment includes one or more alignment devices and / or systems, and the position of the marks on the substrate must be accurately measured by these alignment devices and / or systems. These alignment devices are actually position measurement devices. Different types of marks and different types of alignment devices and / or systems are known from different periods and different manufacturers. A system widely used in current lithography equipment is based on a self-reference interferometer as described in U.S. Patent No. 6,961,116 (den Boef et al.), which is incorporated herein by reference in its entirety. Typically, the marks are measured separately to obtain X and Y positions. The combined X and Y measurements can be performed using the technology described in U.S. Publication No. 2009 / 195768A (Bijnen et al.), which is also incorporated herein by reference in its entirety.

[0067] The terms "inspection equipment", "metrology equipment", etc. may be used herein to refer to a device or system for measuring characteristics of a structure (e.g., overlay error, critical dimension parameters) or for use in a lithography equipment (e.g., alignment equipment) for checking the alignment of a wafer.

[0068] Figure 4AA schematic diagram of a cross-sectional view of a metrology apparatus 400 according to some embodiments is shown. In some embodiments, the metrology apparatus 400 may be implemented as part of a lithography apparatus 100 or 100'. The metrology apparatus 400 may be configured to align a substrate (e.g., substrate W) relative to a patterning device (e.g., patterning device MA). The metrology apparatus 400 may be further configured to detect the position of alignment marks on the substrate and use the detected positions of the alignment marks to align the substrate relative to the patterning device or other components of the lithography apparatus 100 or 100'. Such alignment of the substrate may ensure accurate exposure of one or more patterns on the substrate.

[0069] In some embodiments, the metrology device 400 may include an illumination system 412, a beam splitter 414, an interferometer 426, a detector 428, a beam analyzer 430, and an overlap calculation processor 432. The illumination system 412 may be configured to provide an electromagnetic narrowband radiation beam 413 having one or more passbands. In an example, the one or more passbands may be within a wavelength spectrum between approximately 500 nm and approximately 900 nm. In another example, the one or more passbands may be discrete narrow passbands within a wavelength spectrum between approximately 500 nm and approximately 900 nm. The illumination system 412 may further be configured to provide one or more passbands having a substantially constant center wavelength (CWL) value over a long period of time (e.g., during the lifetime of the illumination system 412). As described above, in the current alignment system, such a configuration of the illumination system 412 may help prevent the actual CWL value from deviating from the desired CWL value. And, as a result, the use of a constant CWL value may improve the long-term stability and accuracy of an alignment system (eg, metrology apparatus 400 ) as compared to current alignment apparatuses.

[0070] In some embodiments, beam splitter 414 can be configured to receive radiation beam 413 and split radiation beam 413 into at least two sub-radiation beams. For example, radiation beam 413 can be split into sub-radiation beams 415 and 417. Figure 4AAs shown. The beam splitter 414 can be further configured to direct the sub-radiation beam 415 onto a substrate 420 placed on a stage 422. In one example, the stage 422 can be moved along a direction 424. The sub-radiation beam 415 can be configured to illuminate an alignment mark or target 418 located on the substrate 420. The alignment mark or target 418 can be coated with a radiation sensitive film. In some embodiments, the alignment mark or target 418 can have a symmetry of one hundred and eighty degrees (i.e., 180°). That is, when the alignment mark or target 418 is rotated 180° around a symmetry axis perpendicular to the plane of the alignment mark or target 418, the rotated alignment mark or target 418 can be substantially the same as the unrotated alignment mark or target 418. The target 418 on the substrate 420 can be a resist layer grating including gratings formed by solid resist lines, a product layer grating, a composite grating stack in an overlapping target structure, etc., the overlapping target structure including a resist grating overlapped or interlaced on the product layer grating. The grating strips can alternatively be etched into the substrate. Such a pattern may be sensitive to chromatic aberrations in the lithographic projection apparatus, in particular the projection system PL, and the illumination symmetry and the presence of such aberrations may manifest themselves in variations in the printed grating. In one example, an in-line method for measuring line width, pitch and critical dimensions in device manufacturing utilizes a technique called "scatterometry". For example, scatterometry methods are described in Raymond et al., "Multiparameter Grating Metrology Using Optical Scatterometry", J. Vac. Sci. Tech. B, Vol. 15, no. 2, pp. 361-368 (1997) and Niu et al., "Specular Spectroscopic Scatterometry in DUV Lithography", SPIE, Vol. 3677 (1999), both of which are incorporated herein by reference in their entirety. In scatterometry, light is reflected by a periodic structure in the target and the resulting reflection spectrum at a given angle is detected. The structure that gave rise to the reflection spectrum is reconstructed, for example using rigorous coupled wave analysis (RCWA) or by comparison with a library of patterns derived from simulations. Thus, scatterometry data of the printed grating are used to reconstruct the grating. Based on knowledge of the printing step and / or other scatterometry processes, the parameters of the grating, such as line width and shape, can be input to the reconstruction process performed by the processing unit PU.

[0071] In some embodiments, the beam splitter 414 may also be configured to receive the diffracted radiation beam 419 and split the diffracted radiation beam 419 into at least two sub-radiation beams, depending on the embodiment. Figure 4AAs shown, the diffracted radiation beam 419 can be divided into diffracted sub-radiation beams 429 and 439.

[0072] It should be noted that even though beam splitter 414 is shown as directing sub-radiation beam 415 to alignment mark or target 418 and directing diffracted sub-radiation beam 429 to interferometer 426, the present disclosure is not limited thereto. It will be apparent to those skilled in the relevant art that other optical arrangements may be used to obtain similar results of illuminating alignment mark or target 418 on substrate 420 and detecting an image of alignment mark or target 418.

[0073] like Figure 4A As shown, the interferometer 426 can be configured to receive the sub-radiation beam 417 and the diffracted sub-radiation beam 429 through the beam splitter 414. In an exemplary embodiment, the diffracted sub-radiation beam 429 can be at least a portion of the sub-radiation beam 415 that can be reflected from the alignment mark or target 418. In the example of this embodiment, the interferometer 426 includes any suitable group of optical elements, such as a combination of prisms, which can be configured to form two images of the alignment mark or target 418 based on the received diffracted sub-radiation beam 429. It should be understood that high quality images do not need to be formed, but the characteristics of the alignment mark 418 should be resolved. The interferometer 426 can be further configured to rotate one of the two images 180° relative to the other of the two images and recombining the rotated and unrotated images in an interferometric manner.

[0074] In some embodiments, the detector 428 may be configured to receive the recombined image via the interferometer signal 427 and detect interference as a result of the recombined image when the alignment axis 421 of the metrology device 400 passes through the center of symmetry of the alignment mark or target 418 (not shown). According to an exemplary embodiment, such interference may be due to the alignment mark or target 418 being 180° symmetrical and the recombined image constructively or destructively interfering. Based on the detected interference, the detector 428 may be further configured to determine the location of the center of symmetry of the alignment mark or target 418 and thus detect the location of the substrate 420. According to an example, the alignment axis 421 may be aligned with a light beam that is perpendicular to the substrate 420 and passes through the center of the image rotation interferometer 426. The detector 428 may also be configured to estimate the location of the alignment mark or target 418 by implementing sensor characteristics and interacting with wafer marking process variations.

[0075] In further embodiments, the detector 428 determines the location of the center of symmetry of the alignment mark or target 418 by performing one or more of the following measurements:

[0076] 1. Measure the position change of various wavelengths (position shift between colors);

[0077] 2. Measuring the positional changes of different orders (positional shifts between diffraction orders); and

[0078] 3. Measure the position change of various polarizations (position shift between polarizations).

[0079] This data can be obtained, for example, using any type of alignment sensor, such as a SMASH (Smart Alignment Sensor Hybrid) sensor, as described in U.S. Patent No. 6,961,116, which employs a self-referencing interferometer with a single detector and four different wavelengths, and extracts the alignment signal in software, or Athena (Advanced Technology using High Order Alignment Enhancement), as described in U.S. Patent No. 6,297,876, which directs each of the seven diffraction orders to a dedicated detector, the entire contents of both of which are incorporated herein by reference.

[0080] In some embodiments, the beam analyzer 430 may be configured to receive and determine the optical state of the diffracted sub-radiation beam 439. The optical state may be a measure of the beam wavelength, polarization, or beam profile. The beam analyzer 430 may further be configured to determine the position of the stage 422 and to correlate the position of the stage 422 with the position of the center of symmetry of the alignment mark or target 418. Thus, the reference stage 422 may accurately know the position of the alignment mark or target 418 and thus the position of the substrate 420. Alternatively, the beam analyzer 430 may be configured to determine the position of the metrology device 400 or any other reference element, so that the center of symmetry of the alignment mark or target 418 may be known by reference to the metrology device 400 or any other reference element. The beam analyzer 430 may be a point or imaging polarimeter with some form of wavelength band selectivity. In some embodiments, the beam analyzer 430 may be directly integrated into the metrology device 400, or connected by several types of optical fibers: single-mode fibers, multimode fibers, or imaging fibers that maintain polarization, according to other embodiments.

[0081] In some embodiments, the beam analyzer 430 may be further configured to determine overlap data between two patterns on the substrate 420. One of the patterns may be a reference pattern on a reference layer. Another pattern may be an exposure pattern on an exposure layer. The reference layer may be an etching layer already present on the substrate 420. The reference layer may be generated by a reference pattern exposed on the substrate by the lithography apparatus 100 and / or 100'. The exposure layer may be an exposed resist layer adjacent to the reference layer. The exposure layer may be generated by an exposure pattern exposed on the substrate 420 by the lithography apparatus 100 or 100'. The exposure pattern on the substrate 420 may correspond to the movement of the substrate 420 through the stage 422. In some embodiments, the measured overlap data may also indicate an offset between the reference pattern and the exposure pattern. The measured overlap data may be used as calibration data to calibrate the exposure pattern exposed by the lithography apparatus 100 or 100' so that after calibration, the offset between the exposure layer and the reference layer may be minimized.

[0082] In some embodiments, the beam analyzer 430 can be further configured to determine a model of the product stacking profile of the substrate 420, and can be configured to measure the overlap, critical dimensions, and focus of the target 418 in a single measurement. The product stacking profile contains information about the stacked product, such as alignment marks, the target 418, the substrate 420, etc., and can include optical signature measurements caused by marking process variations, which are a function of illumination variations. The product stacking profile can also include product grating profiles, mark stacking profiles, mark asymmetry information, etc. As described in U.S. Patent No. 8,706,442, a device called Yieldstar that can be manufactured by ASML of Veldhoven, the Netherlands TM An example of a beam analyzer 430 is found in the metrology equipment of , which is incorporated herein by reference in its entirety. The beam analyzer 430 can be further configured to process information related to specific characteristics of the exposure pattern in the layer. For example, the beam analyzer 430 can process overlay parameters (an indication of the positioning accuracy of a layer relative to the previous layer on the substrate or an indication of the positioning accuracy of a first layer relative to a mark on the substrate), focus parameters, and / or critical dimension parameters of the depicted image in the layer (e.g., line width and its variation). Other parameters are image parameters related to the quality of the depicted image of the exposure pattern.

[0083] In some embodiments, an array of detectors (not shown) can be connected to the beam analyzer 430 and allow the possibility of accurate stack profile detection, as described below. For example, the detector 428 can be an array of detectors. For the detector array, there may be a variety of options: a multimode fiber bundle, a discrete pin detector for each channel, or a CCD or CMOS (linear) array. For stability reasons, the use of a bundle of multimode optical fibers allows any dissipative elements to be remotely located. Although discrete PIN detectors offer a larger dynamic range, each requires a separate preamplifier. Therefore, the number of elements is limited. CCD linear arrays provide many elements that can be read out at high speed, which is particularly interesting if phase-stepping detection is used.

[0084] In some embodiments, the second beam analyzer 430' may be configured to receive and determine the optical state of the diffracted sub-radiation beam 429, such as Figure 4B As shown. The optical state can be a measure of the beam wavelength, polarization, beam profile, etc. The second beam analyzer 430' can be identical to the beam analyzer 430. Alternatively, the second beam analyzer 430' can be configured to perform at least all the functions of the beam analyzer 430, such as determining the position of the stage 422 and the position of the associated stage 422 and the position of the symmetry center of the alignment mark or target 418. Therefore, the position of the alignment mark or target 418 and therefore the position of the substrate 420 can be accurately known with reference to the stage 422. The second beam analyzer 430' can also be configured to determine the position of the measurement device 400 or any other reference element, so that the symmetry center of the alignment mark or target 418 can be known with reference to the measurement device 400 or any other reference element. The second beam analyzer 430' can be further configured to determine the overlap data between the two patterns and the model of the product stacking profile of the substrate 420. The second beam analyzer 430' can also be configured to measure the overlap, critical dimension and focus of the target 418 in a single measurement.

[0085] In some embodiments, the second beam analyzer 430' may be directly integrated into the measurement device 400, or the second beam analyzer 430' may be connected via several types of optical fibers: single-mode optical fibers that maintain polarization, multimode optical fibers, or imaging optical fibers, according to other embodiments. Alternatively, the second beam analyzer 430' and the beam analyzer 430 may be combined to form a single analyzer (not shown) that is configured to receive and determine the optical state of the two diffracted sub-radiation beams 429 and 439.

[0086] In some embodiments, the processor 432 receives information from the detector 428 and the beam analyzer 430. For example, the processor 432 can be an overlap calculation processor. The information may include a model of the product stacking profile constructed by the beam analyzer 430. Alternatively, the processor 432 can use the received information about the product marking to construct a model of the product marking profile. In either case, the processor 432 uses or combines the model of the product marking profile to build a model of the stacked product and the overlay mark profile. Then, the stacking model is used to determine the overlay offset and minimize the spectral impact on the overlay offset measurement. The processor 432 can create a basic correction algorithm based on the information received from the detector 428 and the beam analyzer 430, which includes but is not limited to the optical state of the illumination beam, the alignment signal, the associated position estimate, and the optical state in the pupil, the image, and the additional plane. The pupil plane is such a plane: in this plane, the radial position of the radiation defines the angle of incidence and the angular position defines the azimuth of the radiation. The processor 432 can use the basic correction algorithm to reference the wafer mark and / or alignment mark 418 to characterize the measurement device 400.

[0087] In some embodiments, the processor 432 may be further configured to determine the sensor-estimated printed pattern position offset error relative to each mark based on information received from the detector 428 and the beam analyzer 430. The information includes, but is not limited to, the product stacking profile, overlap measurement results, critical dimensions, and focus of each alignment mark or target 418 on the substrate 420. The processor 432 may group the marks into sets of similar constant offset errors using a clustering algorithm and create an alignment error offset correction table based on this information. The clustering algorithm may be based on overlap measurements, position estimates, and additional optical stacking process information associated with each set of offset errors. Overlap is calculated for a plurality of different marks, for example, the marks are overlap targets with positive and negative deviations around the planned overlap offset. The target measuring the minimum overlap is used as a reference (because it is measured with the best accuracy). Based on this measured smaller overlap and the known planned overlap of its corresponding target, the overlap error can be inferred. Table 1 illustrates how to do this. The minimum measured overlap in the example is -1nm. However, this is related to a target with a planned overlap of -30nm. Therefore, the process must have introduced an overlap error of 29nm.

[0088]

[0089] The minimum value can be used as a reference point, and relative to this, the offset between the measured overlap and the expected overlap due to the planned overlap can be calculated. This offset determines the overlap error of each mark or a combination of marks with similar offsets. Therefore, in the example of Table 1, the minimum overlap measured at the target position is -1nm and the planned overlap is 30nm. The difference between the expected overlap and the measured overlap at other targets is compared with this reference. A table such as Table 1 can also be obtained from the mark and target 418 under different illumination settings, and the illumination settings and their corresponding calibration factors that lead to the minimum overlap error can be determined and selected. Thereafter, the processor 432 can group the marks into a collection of similar overlap errors. The criteria for grouping the marks can be adjusted based on different process controls, such as different error tolerances for different processes.

[0090] In some embodiments, the processor 432 can confirm that all or most members of the group have similar offset errors and apply individual offset corrections from the clustering algorithm to each mark based on additional optical stack measurements of each mark. The processor 432 can determine the correction result for each mark and, for example, feed the correction result back to the lithographic apparatus 100 or 100' by feeding the correction result back into the alignment apparatus 400 to correct the error in the overlay.

[0091] Exemplary Metrology System Using Integrated Photonics

[0092] Thus far, the discussion has focused on a metrology device that uses optical hardware (e.g., beam splitter 414, interferometer 426, etc.) to collect (e.g., scattered) light received by a target structure and direct the light toward a detector. Optical hardware is also often required to correct for aberrations or otherwise condition radiation that has been scattered by the target structure. In some examples, the size requirements of the light directing optical hardware may be accompanied by a large sensor footprint, for example, on the order of approximately 20 mm×20 mm or more. In these examples, due to the large sensor footprint area, the metrology system may include only one or a few devices for inspecting the wafer, which may affect the ability to inspect a large number of wafers within a given time frame. For example, the speed of wafer inspection can be increased by reducing the time per measurement (e.g., by collecting more photons) and / or increasing the number of available measurement devices (e.g., by reducing the device footprint and adding more measurement devices). Embodiments of the present disclosure provide structures and functions for performing inspections of structures on a substrate more quickly and efficiently.

[0093] Figure 5A schematic diagram of a metrology system 500 is shown in accordance with some embodiments. In some embodiments, the metrology system 500 includes a metrology device 502. The metrology device 502 may include an illumination system 508, one or more optical elements 524, and a detector 528. The illumination system 508 may include a substrate 510, sources 512 and 514 (or a first source and a second source), and resonators 518 and 520 (or a first resonator and a second resonator). The illumination system 508 may include additional structures, such as one or more additional sources 516, one or more additional resonators 522, and / or a multiplexer 530. The metrology device 502 may also include additional structures, such as an optical element 526 and other structures not shown here but described with reference to other figures (e.g., an illumination monitor).

[0094] In some embodiments, all or some of the structures of the measurement apparatus of the embodiments herein may be part of an integrated photonic device. For example, at least a portion of the illumination system 508 may be implemented on a substrate 510 as part of an integrated photonic device that includes at least a source 512 and a resonator 518. It should be understood that Figure 5 The arrangement shown in (e.g., where the source, resonator, and multiplexer are on a substrate) is merely an example, and embodiments are contemplated in which certain structures may be provided separate from substrate 510 or on multiple substrates that are combined together. For example, at least a portion of illumination system 508 may include an integrated photonic device that includes at least source 512 and resonator 518. Those skilled in the art will appreciate that a variety of arrangements are contemplated.

[0095] In some embodiments, illumination system 508 can be configured to generate radiation beam 532 or more than one radiation beam 532. To generate radiation beam 532, source 512, source 514, and / or one or more additional sources 516 can generate radiation having different wavelength bands. For example, source 512 can generate a first wavelength band, and source 514 can generate a second wavelength band different from the first wavelength band—that is, the first source and the second source can be configured to generate respective different first and second wavelength bands.

[0096] In some embodiments, source 512, source 514, and one or more additional sources 516 may be similar to lasers, for example, each source may include a superluminescent diode (SLED). A laser-like source may include a pn junction and a finite gain medium (e.g., one-way), and produce amplified spontaneous emission (usually more intense than a typical light emitting diode (LED)). However, unlike a laser, a laser-like source lacks feedback in the gain medium for lasing. A laser-like source may include a wider continuous spectrum than a laser.

[0097] In some embodiments, resonator 518, resonator 520, and one or more additional resonators 522 may be optically coupled to respective ones of source 512, source 514, and one or more additional sources 516, such as Figure 5 512 are shown by double-headed arrows therebetween, respectively. Although the functions and relationships between resonator 518 and source 512 are described herein, it should be understood that resonator 520, source 514, one or more additional resonators 522, and one or more additional sources 516 may have similar functions and relationships to those described with reference to resonator 518 and source 512. In some embodiments, source 512 may optically interact with resonator 518 to change the characteristics of radiation from source 512. For example, resonator 518 may provide a feedback mechanism to source 512 so that source 512 may increase gain and narrow the wavelength produced by source 512 (e.g., operate more like a laser). Thus, resonator 518 may narrow a first wavelength band (e.g., of source 512).

[0098] In some embodiments, the resonator 518 may include a gain medium. The resonator 518 may include, for example, a ring resonator, a medium bounded on opposite sides by two reflectors, etc. The resonator 518 may be adjusted based on user input (e.g., by changing the temperature (thermo-optic)). In particular, one or more characteristics of the resonator 518 may be adjusted. The adjusted one or more characteristics of the resonator 518 may be, for example, the resonant wavelength and / or the Q factor. Additionally or alternatively, other adjustment mechanisms (e.g., piezoelectric, piezo-optic, electro-optic, electrostatic, etc.) may be used. For example, a variable absorber or transmission device may be used to change local material properties by using at least one of the above-mentioned adjustment mechanisms to cause radiation attenuation or leakage. Adjustment mechanisms capable of higher modulation frequencies may be suitable for fast wavelength switching to increase wafer production (e.g., piezoelectric devices may operate in the kilohertz to megahertz range). The adjustment may also be used in a feedback loop to stabilize the source 512. As mentioned, other resonators and sources function in a similar manner. In a non-limiting example of multiple sources and resonators, the first resonator and the second resonator can be optically coupled to respective ones of the first source and the second source and configured to narrow respective ones of the first wavelength band and the second wavelength band. In another non-limiting example, the third source can be configured to generate a third wavelength band of the radiation beam 532 that is different from the first wavelength band and the second wavelength band. The third resonator can be optically coupled to the third source and configured to narrow the third wavelength band.

[0099] In some embodiments, tunable wavelength filters may also be used instead of or in addition to resonators. Some examples of tunable wavelength filters include acousto-optic tunable filters, wavelength multiplexers / demultiplexers, wavelength switches, tunable waveguides, monochromators, Bragg filters, etc. Ring resonators may also be used as wavelength filters.

[0100] In some embodiments, a multiplexer 530 can be disposed downstream of resonator 518, resonator 520, and / or one or more additional resonators 522. Multiplexer 530 can combine radiation from resonator 518, resonator 520, and / or one or more additional resonators 522 so that, for example, received radiation of different wavelengths is directed along a shared optical path. In a non-limiting example, multiplexer 530 can be configured to direct radiation corresponding to a first wavelength band and radiation corresponding to a second wavelength band along a shared optical axis (even more wavelengths can be multiplexed). Illumination system 508 can be configured to generate two or more narrow wavelength bands simultaneously or sequentially.

[0101] In some embodiments, using resonator 518, resonator 520, and / or one or more additional resonators 522, illumination system 508 can select at least one of the narrow wavelength bands. Using source 512, source 514, and one or more additional sources 516, illumination system 508 can be configured to operate over a wide wavelength range, such as between approximately ultraviolet (UV) to infrared (IR) (e.g., approximately 200 nm to 2000 nm). At least one narrow wavelength band can be approximately 20 nm wide or less, 10 nm wide or less, 5 nm wide or less, 1 nm wide or less, 0.5 nm wide or less, or 0.1 nm wide or less. Illumination system 508 can adjust the narrowed wavelength band based on modulation of the resonant wavelength of the corresponding resonator (e.g., using an adjustment mechanism such as piezoelectric, piezo-optic, electro-optic, electrostatic, etc.). In a non-limiting example, the illumination system is configured to adjust a width of at least one of the corresponding narrowed wavelength bands in the first wavelength band and the second wavelength band based on modulation of a resonant wavelength of a corresponding resonator in the first resonator and the second resonator. In some embodiments, the illumination system 508 can be configured to operate within a wavelength range, such as within a visible range (e.g., approximately 400 nm to 800 nm) and / or an infrared range (e.g., approximately 800 nm to 1800 nm).

[0102] In some embodiments, the set of source 512, source 514, and one or more additional sources 516 can cover a wide range of wavelengths without gaps. To avoid gaps in the wavelengths delivered by illumination system 508, the sources can have overlapping spectral bands (e.g., one or more shared wavelengths at the overlap). In a non-limiting example, the first wavelength band and the second wavelength band include shared wavelengths.

[0103] In some embodiments, a single optical element in one or more optical elements 524 and optical element 526 may be a single optical component (e.g., a lens) or a system of multiple components, such as any number and arrangement of lenses and reflectors. One or more optical elements 524 may receive multiplexed radiation from multiplexer 530. That is, one or more optical elements 524 may be disposed downstream of multiplexer 530. One or more optical elements 524 may direct radiation beam 532 toward target structure 534. Target structure 534 may be disposed on substrate 536 (e.g., a wafer) (also referred to as a "target substrate"). Target structure 534 may include alignment marks, product features, etc. Target structure 534 may reflect, refract, diffract, scatter radiation, or otherwise process radiation to produce radiation 538. For ease of discussion but without limitation, radiation will always be referred to as scattered radiation. Detector 528 may receive scattered radiation 538. Optical element 526 may be used to direct and / or focus scattered radiation 538 onto detector 528. One or more optical elements 524 and optical elements 526 may be at least one of an illumination redirecting element (e.g., a reflector) and a focusing element. One or more optical elements 524 and / or optical elements 526 may be disposed on substrate 510 (e.g., monolithically manufactured or assembled from separate modular components).

[0104] In some embodiments, the multiplexer 530 may be optional (e.g., may be omitted). In the absence of the multiplexer 530, the one or more optical elements 524 may be disposed downstream of the resonator 518, the resonator 520, and / or the one or more additional resonators 522. Radiation 522 from the resonator 518, the resonator 520, and / or the one or more additional resonators may be directed to one of the one or more optical elements 524. In some embodiments, radiation from the resonator 518, the resonator 520, and / or the one or more additional resonators 522 may be directed (e.g., along different optical paths) to respective ones of the one or more optical elements 524. The respective ones of the one or more optical elements 524 may then output radiation, for example, at different angles.

[0105] In some embodiments, at least one of the one or more optical elements 524 may include a polarizer. In embodiments having different optical paths for each source, one or more optical elements 524 on each optical path may include a polarizer. The illumination system 508 may adjust the polarization of the radiation beam 532 based on user input. For example, a user may desire a given wavelength and polarization. In this case, the user may provide input to the vector measurement system 500 (e.g., through a user interface). The illumination system 508 may then adjust the polarizer. In some embodiments, the illumination system may select an optical path to be activated (e.g., an optical path associated with source 512) while not powering other sources or otherwise suppressing the output of other sources.

[0106] In some embodiments, scattered radiation 538 may be received at detector 528. Detector 528 may generate a measurement signal based on the received radiation. Detector 528 includes an image capture device (eg, a camera). The measurement signal may include data of the detected image.

[0107] In some embodiments, different illumination systems may be used. For example, a broadband white light source may be used. However, a white light source produces its full spectrum when powered, and a narrowband wavelength range is selected from it by a wavelength filtering element. However, most of the spectrum is wasted in doing so (e.g., photons that are not within the narrowband wavelength range are discarded). Illumination system 508 may be able to overcome this inefficient use of illumination energy. For example, a resonator 518 may be used to select a narrowband wavelength range from source 512. Since other wavelengths may not be needed at a given moment, source 514 and / or one or more additional sources 516 may not be powered, while source 512 is powered. In some embodiments, source 514 and / or one or more additional sources 516 may have a suppressed output when source 512 is powered. In order to suppress the output, for example, an opaque element, an element with adjustable transmittance, or radiation directed into a beam collector may be used to block the radiation. In a non-limiting example, the first source is configured to be unpowered or have a suppressed output when the second source is powered.

[0108] In some embodiments, the metrology device 502 may include any number of waveguides to direct radiation, for example, from one element to the next. In some embodiments, the waveguides may optically couple a resonator (e.g., resonator 518) to its respective source (source 512). The waveguides may be fabricated (e.g., monolithically) on the substrate 510.

[0109] In some embodiments, the structure of the measurement device 502 can be modular. For example, the substrate 510 can be a modular structure. The source diode can have a limited life. It is convenient to remove and replace worn parts. Therefore, the source 512, the source 514, one or more additional sources 516, the resonator 518, the resonator 520 and / or one or more additional resonators 522 can be on a detachable part of the illumination system 508. These structures can still be integrated photonic devices implemented on the substrate 510. For example, the sources can be their own integrated photonic device components that can be assembled onto the substrate 510. Interfaces can be designed in which different wavelength bands and / or polarizations can be output at specific locations on the substrate (for example, a design with aligned sources and resonators).

[0110] In some embodiments, the measurement system 500 may include a second measurement device 504 and / or one or more additional measurement devices 506. The structure and function of the measurement device 504 and / or one or more additional measurement devices 506 may be the same or similar to the measurement device 502. In some embodiments, the measurement device 504 may be used to interrogate or inspect the target structure 540 (or a second target structure). One or more additional measurement devices 506 may be used to interrogate or inspect one or more additional target structures 542 (or corresponding structures). In a non-limiting alternative description, the measurement system 500 may further include a second illumination system on the second substrate. The second illumination system may be configured to generate a second radiation beam. The second illumination system may include a first source and a second source configured to generate corresponding different first and second wavelength bands of the second beam. The second illumination system may include a first resonator and a second resonator optically coupled to corresponding sources of the first and second sources of the second illumination system. The first resonator and the second resonator may be configured to narrow corresponding wavelength bands in the first and second wavelength bands of the second beam. The metrology system 500 may also include a second optical element configured to direct the second beam toward a second target structure and a second detector configured to receive radiation scattered by the second target structure and to generate a measurement signal based on the received radiation scattered by the second target structure. It should also be appreciated that additional iterations of illumination systems, optical elements, and detectors are contemplated.

[0111] As mentioned above, the speed of wafer inspection can be increased by, for example, increasing the number of available measurement devices (e.g., by reducing the device footprint and adding more devices). In some embodiments, the implementation of integrated photonics allows the device footprint to be reduced by eliminating the need for large optical hardware. In some embodiments, a metrology device based on integrated photonics (e.g., metrology device 502) can include a device having a size of less than approximately 2000 mm. 2 , 1000mm2 , 500mm 2 , 100mm 2 , 50mm 2 , 25mm 2 or 16mm 2 PIC-based metrology systems may include footprints having widths less than approximately 40 mm, 30 mm, 20 mm, 10 mm, 7 mm, 5 mm, or 4 mm. By transfer characteristics, these dimensions may also apply to the footprints of individual components within integrated photonics-based metrology devices.

[0112] Figure 6 608 according to some embodiments. Figure 5 Any structure and functionality described may also be included in the reference Figure 6 For example, in some embodiments, Figure 6 The illumination system 608 shown may provide illumination system 508 ( Figure 5 ) for a more detailed view.

[0113] Unless otherwise stated, Figure 6 has Figure 5 Elements with similar reference numerals may have similar structure and function (e.g., the reference numerals share the rightmost two digits). For example, in some embodiments, source 612, source 614, one or more additional sources 616, resonator 618, resonator 620, and / or one or more additional resonators 622 of illumination system 608 may have the same or similar structure and be described above with reference to FIG. Figure 5 The functionality described for source 512 , source 514 , one or more additional sources 516 , resonator 518 , resonator 520 , and / or one or more additional resonators 522 .

[0114] In some embodiments, the illumination system 608 may also include an illumination monitor 644. The illumination monitor 644 may include a spectrum monitor 646 and / or a multiplexer 648. The spectrum monitor 646 may include a spectrometer, a spectrum analyzer, or the like.

[0115] In some embodiments, the illumination system 608 can send a portion of the radiation output by the resonator 618, the resonator 620, and / or one or more additional resonators 622 (e.g., using a beam splitting element) to an illumination monitor 644. The illumination monitor 644 can monitor the radiation beam (e.g., the radiation beam 532 ( Figure 5)). For example, the irradiation monitor 644 can determine whether the radiation output by the resonator 618, the resonator 620, and / or the one or more additional resonators 622 has suitable measurement characteristics (e.g., stability, dose, position, intensity, polarization, spectral bandwidth, wavelength, etc.). The multiplexer 648 can combine the radiation from the resonator 618, the resonator 620, and / or the one or more additional resonators 622 so that radiation of different wavelengths is directed to the spectral monitor 646. In some embodiments, the radiation sent to the irradiation monitor 644 may have been (e.g., using the multiplexer 530 ( Figure 5 )) are multiplexed and multiplexer 648 may be omitted. Irradiation monitor 644 may be configured to analyze non-multiplexed radiation (the multiplexer is optional).

[0116] In some embodiments, the illumination monitor 644 can monitor the illumination provided by the source and the resonator (e.g., the source 512 and the resonator 518 ( Figure 5 )) forms a feedback loop.

[0117] Figure 7 718 according to some embodiments. Figure 5 and Figure 6 Any structure and functionality described may be included in the reference Figure 7 For example, in some embodiments, Figure 7 The illustrated ring resonator 718 may provide a more detailed view of the resonator 518, the resonator 520, and / or the one or more additional resonators 522. Unless otherwise indicated, Figure 7 In the Figure 5 and Figure 6 Elements with similar reference numerals may have similar structure and function (eg, the reference numerals share the two rightmost digits).

[0118] In some embodiments, the ring resonator 718 includes a waveguide 750, a waveguide 752, and a ring structure 754. The ring structure 754 may include a waveguide. The structure of the ring resonator 718 may be implemented on the substrate 710. The waveguides 750 and 752 are arranged close to the ring waveguide (e.g., in the order of the wavelength of the radiation) so that they are optically coupled.

[0119] In some embodiments, radiation from a source (e.g., source 512) can be input and directed through waveguide 750. As the input radiation passes through ring structure 754, at least a portion of the input radiation can couple into ring structure 754. Ring structure 754 includes a resonant wavelength such that radiation including wavelengths approximately at the resonant wavelength is coupled into ring structure 754, while other wavelengths are less likely to couple into ring structure 754. The radiation in ring structure 754 can then be coupled to waveguide 752. The radiation coupled to waveguide 752 can be directed back to the source (e.g., source 512). Figure 5 )) to further interact (e.g., amplify and / or narrow the wavelength produced by the source).

[0120] although Figure 7 , but in some embodiments, the ring structure 754 may include two or more rings. An example of two or more rings may be when implementing an add / drop filter configuration.

[0121] In some embodiments, ring resonator 718 may be a sub-portion of a larger resonator. For example, source (e.g., source 512 ( Figure 5 )) may include other parts of the resonator structure that, when combined with the ring resonator 718, may form a complete resonator. It should be appreciated that these features may also be used to implement, for example, the resonator 518 ( Figure 5 ) in which the resonator 518 is not limited to a ring resonator.

[0122] Figure 8 Graph 800 of a spectrum produced by an illumination system according to some embodiments is shown. Graph 800 provides a spectrum of light produced by an illumination system having multiple sources (e.g., source 512, source 514, and / or one or more additional sources 516 ( Figure 5 A qualitative representation of the intensity and wavelength provided by the illumination of ). The vertical axis represents intensity and the horizontal axis represents wavelength.

[0123] In some embodiments, a source (e.g., source 512 ( Figure 5 )) can generate wavelength band 802. Another source (e.g., source 514 ( Figure 5 )) can generate wavelength band 804. Similar relationships are as follows for additional sources and wavelength bands 806 and 808. It should be understood that the number of sources used and the wavelength bands generated are not limited to Figure 8 Four are depicted in FIG, and more or fewer may be used.

[0124] In some embodiments, the upper wavelengths of wavelength band 802 partially overlap with the lower wavelengths of wavelength band 804. The upper wavelengths of wavelength band 804 partially overlap with the lower wavelengths of wavelength band 806. The upper wavelengths of wavelength band 806 partially overlap with the lower wavelengths of wavelength band 808. Each wavelength band shares one or more wavelengths, enabling an illumination system (e.g., illumination system 508) to cover a continuous spectrum of light.

[0125] In some embodiments, a resonator (e.g., resonator 518 ( Figure 5 )) can narrow the wavelength band 802 so that the generated wavelength is now contained in the narrowed wavelength band 812. Another resonator (e.g., resonator 520 ( Figure 5 )) can narrow wavelength band 804 so that the generated wavelength is now contained in narrowed wavelength band 814. A similar relationship follows for additional resonators and narrowed wavelength bands 816 and 818. As mentioned previously, the position of the narrowed wavelength band can be moved and the width of the narrowed wavelength band adjusted based on the adjustment of the corresponding resonator.

[0126] Fig. 9 The method steps for performing the functions described herein according to some embodiments are shown. The steps may be performed in any conceivable order. Fig. 9 In addition, the method steps described above do not require execution of all steps. Fig. 9 The method steps are merely examples of steps and are not restrictive. Figure 8 The described embodiments contemplate further method steps and functions.

[0127] At step 902, a radiation beam can be generated using an illumination system. The illumination system can include first and second sources and corresponding first and second resonators.

[0128] At step 904, a first wavelength band of a beam may be generated using a first source.

[0129] A second wavelength band of the beam may be generated using a second source at step 906. The second wavelength band is different from the first wavelength band.

[0130] At step 908, the first wavelength band may be narrowed using the first resonator.

[0131] At step 910, a second wavelength band may be narrowed using a second resonator.

[0132] At step 912, the beam may be directed toward a target structure.

[0133] At step 914, a detector may be used to receive radiation scattered by the target structure.

[0134] At step 916 , a detector may be used to generate a measurement signal based on the received radiation.

[0135] In some embodiments, optical measurements performed on a substrate product (e.g., a wafer) may include capturing (e.g., using a camera detector) a high-resolution image of a target structure on the substrate. A commercially available example is the aforementioned ASML's Yieldstar TM . Embodiments of the present disclosure (for example, Figures 5 to 8 ) can also be used to perform image capture measurements. Figure 5 For example, based on the measurement signals generated by the detector 528, lithographic characteristics of the substrate 536 (e.g., overlay error, critical dimension parameters, etc.) can be determined. In addition, known computational enhancement techniques can be used to enhance image clarity / focus of the inspection image and / or reduce aberrations caused by the optics of the metrology device 502.

[0136] In some embodiments, when performing a lithography process on a substrate, it is important that the substrate is accurately aligned within a lithography apparatus so that a newly applied layer is accurately positioned (overlaid) on top of an existing layer on the substrate. Therefore, the lithography apparatus relies on a metrology system to measure the position of the substrate relative to the position of the projected illumination pattern of the new layer (e.g., Figure 1A A commercially available example of an alignment sensor is the aforementioned SMASH sensor from ASML of the Netherlands. TM and ATHENA TM Sensor. The structure and function of the alignment sensor has been discussed with reference to FIG. 4 and US Patent No. 6,961,116 and US Application No. 2009 / 195768, the entire contents of which are incorporated herein by reference.

[0137] Further aspects of the invention are set out in the following numbered aspects.

[0138] 1. A system comprising:

[0139] an illumination system on a substrate, the illumination system configured to generate a radiation beam and comprising: first and second sources configured to generate respective different first and second wavelength bands, and first and second resonators optically coupled to respective ones of the first and second sources and configured to narrow respective ones of the first and second wavelength bands;

[0140] an optical element configured to direct the beam toward a target structure; and

[0141] A detector is configured to receive radiation returned from the target structure and to generate a measurement signal based on the received radiation.

[0142] 2. The system of clause 1, wherein the illumination system is further configured to adjust the respective narrowed wavelength bands of the first and second wavelength bands based on adjustment of the resonant wavelength of the respective resonator of the first and second resonators.

[0143] 3. The system of aspect 1, wherein the first wavelength band and the second wavelength band comprise shared wavelengths.

[0144] 4. A system according to aspect 1, wherein the illumination system is further configured to operate within a wide wavelength range of approximately 200nm to 2000nm, and to select at least one narrowed wavelength band among the corresponding narrowed wavelength bands in the first wavelength band and the second wavelength band from the wide wavelength range.

[0145] 5. The system of aspect 1, wherein at least one of the respective narrowed ones of the first and second wavelength bands is approximately 20 nm wide or less.

[0146] 6. The system of aspect 1, wherein at least one of the respective narrowed ones of the first and second wavelength bands is approximately 1 nm wide or less.

[0147] 7. The system according to aspect 1, wherein:

[0148] The illumination system is further configured to adjust a width of at least one of the respective narrowed ones of the first and second wavelength bands based on modulation of one or more characteristics of the respective ones of the first and second resonators; and

[0149] The one or more characteristics include at least one of a resonant wavelength and a Q factor.

[0150] 8. The system of aspect 1, wherein the illumination system further comprises:

[0151] a third source configured to generate a third wavelength band of the beam that is different from the first wavelength band and the second wavelength band; and

[0152] A third resonator is optically coupled to the third source device and is configured to narrow the third wavelength band.

[0153] 9. The system of aspect 1, wherein the first source is configured to be unpowered or to have an inhibited output when the second source is powered.

[0154] 10. The system of aspect 1, wherein the substrate further comprises:

[0155] A multiplexer element is configured to direct radiation corresponding to the first wavelength band and radiation corresponding to the second wavelength band along a shared optical axis.

[0156] 11. The system of aspect 1, wherein the illumination system further comprises an illumination monitor configured to monitor one or more characteristics of the beam, and wherein the illumination system is further configured to send a portion of the beam to the illumination monitor.

[0157] 12. The system of aspect 11, wherein the one or more characteristics include at least one of dose, position, intensity, polarization, spectral bandwidth, and wavelength.

[0158] 13. The system of aspect 11, wherein:

[0159] At least the first source and the first resonator are further configured to form a feedback loop;

[0160] The irradiance monitor is further configured to monitor radiation in the feedback loop; and

[0161] The illumination system is further configured to stabilize characteristics of the beam based on the monitored radiation in the feedback loop.

[0162] 14. The system of clause 11, wherein the irradiation monitor is integrated on the substrate.

[0163] 15. The system of clause 1, wherein at least a portion of the illumination system comprises an integrated photonic device including at least the first source and the first resonator.

[0164] 16. The system of aspect 1, wherein the system has a diameter of less than approximately 2000 mm. 2 , 1000mm 2 , 500mm 2 , 100mm 2 , 50mm 2 , 25mm 2 or 16mm 2 occupied area.

[0165] 17. The system of aspect 1, wherein the detector comprises an image capture device.

[0166] 18. The system of aspect 1, wherein each of the first source and the second source comprises a superluminescent diode.

[0167] 19. The system of aspect 1, wherein each of the first and second resonators comprises a ring resonator.

[0168] 20. The system of aspect 1, wherein the illumination system:

[0169] further comprising a first polarizer; and

[0170] Further configured to adjust the polarization of the beam based on user input.

[0171] 21. The system of aspect 20, wherein:

[0172] The illumination system further includes a second polarizer associated with an optical path of the second source;

[0173] the first polarizer is associated with an optical path of the first source; and

[0174] The illumination system is further configured to select at least one of optical paths of the first source and the second source.

[0175] 22. The system of aspect 1, wherein at least one of the first source, the second source, the first resonator, and the second resonator is modular.

[0176] 23. The system according to aspect 1, further comprising:

[0177] a second illumination system on a second substrate, the second illumination system configured to produce a second radiation beam and comprising: first and second sources configured to produce respective different first and second wavelength bands of the second beam, and first and second resonators optically coupled to respective ones of the first and second sources of the second illumination system and configured to narrow respective ones of the first and second wavelength bands of the second beam;

[0178] a second optical element configured to direct the second beam toward a second target structure; and

[0179] A second detector is configured to receive radiation from the second target structure and to generate a measurement signal based on the received radiation.

[0180] 24. The system according to aspect 1, further comprising:

[0181] an additional illumination system located on the corresponding additional substrate, the additional illumination system configured to produce a corresponding radiation beam and comprising: corresponding first and second sources configured to produce corresponding different first and second wavelength bands of the corresponding beam, and corresponding first and second resonators optically coupled to the corresponding first and second sources and configured to narrow corresponding ones of the first and second wavelength bands of the corresponding beam;

[0182] an additional optical element configured to direct the corresponding beam toward a corresponding target structure; and

[0183] An additional detector is configured to receive radiation from the corresponding target structure and to generate a corresponding measurement signal based on the received radiation scattered by the corresponding target structure.

[0184] 25. A photolithography apparatus:

[0185] an illumination device configured to illuminate the pattern forming device with a pattern;

[0186] a projection system configured to project an image of the pattern onto a target substrate; and

[0187] A measurement system, the measurement system comprising:

[0188] An illumination system located on a substrate, the illumination system being configured to generate a radiation beam and comprising:

[0189] first and second sources configured to generate respective different first and second wavelength bands, and

[0190] first and second resonators optically coupled to respective ones of the first and second sources and configured to narrow respective ones of the first and second wavelength bands;

[0191] an optical element configured to direct the beam toward a target structure; and

[0192] A detector is configured to receive radiation from the target structure and to generate a measurement signal based on the received radiation.

[0193] 26. A method comprising:

[0194] generating a radiation beam using an illumination system on the substrate, the illumination system comprising first and second sources and first and second resonators;

[0195] generating a first wavelength band of beams using said first source;

[0196] generating a second wavelength band of the beam using the second source, the second wavelength band being different from the first wavelength band;

[0197] narrowing the first wavelength band using the first resonator;

[0198] narrowing the second wavelength band using the second resonator;

[0199] directing the beam toward a target structure;

[0200] receiving radiation from the target structure using a detector; and

[0201] A measurement signal is generated based on the received radiation using the detector.

[0202] Although there are some differences between SMASH-type sensors (e.g., implementing alignment within a lithography device) and Yieldstar-type sensors (e.g., implementing product inspection outside a lithography device), concepts such as reduced footprint metrology devices, integrated photonics for illumination, and using multiple metrology devices in parallel to measure more targets in a given time apply to both sensor types.

[0203] Although specific reference may be made herein to the use of lithographic apparatus in IC manufacturing, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, LCDs, thin film heads, etc. It will be understood by those skilled in the art that in the context of such alternative applications, the terms "wafer" or "die" used herein may be considered synonymous with the more general terms "substrate" or "target portion", respectively. The substrate referred to herein may be processed before or after exposure in, for example, a tracking unit (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a measurement unit, and / or an inspection unit. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. In addition, a substrate may be processed more than once, for example to produce a multi-layer IC, so the term substrate used herein may also refer to a substrate that already contains multiple layers that have been processed.

[0204] Although specific reference has been made above to the use of embodiments of the present disclosure in the context of optical lithography, it should be understood that the present disclosure may be used in other applications, such as imprint lithography, and is not limited to optical lithography where the context permits. In imprint lithography, the topography in the patterning device defines the pattern created on the substrate. The topography of the patterning device can be pressed into a layer of resist provided to the substrate, and the resist is then cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist is cured, the patterning device is removed from the resist, leaving a pattern therein.

[0205] It should be understood that the phraseology or terminology herein is for the purpose of description rather than limitation, so that the phraseology or terminology of the present disclosure will be interpreted by one or more persons skilled in the relevant art based on the teachings herein.

[0206] As used herein, the terms "radiation", "beam", "light", "irradiation" and the like may encompass all types of electromagnetic radiation, such as ultraviolet (UV) radiation (e.g., having a wavelength λ of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm), extreme ultraviolet (EUV or soft X-ray) radiation (e.g., having a wavelength in the range of 5 nm to 20 nm, such as 13.5 nm), or hard X-rays operating at less than 5 nm, and particle beams, such as ion beams or electron beams. Typically, radiation having a wavelength between approximately 400 nm and approximately 700 nm is considered visible radiation; radiation having a wavelength between approximately 780 nm and 3000 nm (or greater) is considered IR radiation. Ultraviolet refers to radiation having a wavelength of approximately 100 nm to 400 nm. In lithography, the term "UV" also applies to wavelengths that may be produced by a mercury discharge lamp: G line 436 nm; H line 405 nm; and / or I line 365 nm. Vacuum UV or VUV (i.e., UV absorbed by gases) refers to radiation having a wavelength of approximately 100 nm to 200 nm. Deep ultraviolet (DUV) generally refers to radiation having a wavelength in the range of from 126 nm to 428 nm, and in some embodiments, an excimer laser may produce DUV radiation used in a lithographic apparatus. It should be understood that radiation having a wavelength in the range of, for example, 5 nm to 20 nm refers to radiation having a particular wavelength band, wherein at least a portion of the wavelength band is in the range of 5 nm to 20 nm.

[0207] As used herein, the term "substrate" describes a material onto which a layer of material is added. In some embodiments, the substrate itself can be patterned, and the material added on top of it can also be patterned, or can remain unpatterned.

[0208] Although specific reference may be made herein to the use of the apparatus and / or system according to the present disclosure in the manufacture of ICs, it should be clearly understood that such an apparatus and / or system has many other possible applications. For example, it may be used to manufacture integrated optical systems, guidance and detection patterns for magnetic domain memories, LCD panels, thin film magnetic heads, etc. It will be understood by those skilled in the art that in the context of such alternative applications, any use of the terms "reticle", "wafer" or "die" herein should be considered to be replaced by the more general terms "mask", "substrate" and "target portion", respectively.

[0209] Although specific embodiments of the present disclosure have been described above, it should be understood that embodiments of the present disclosure may be implemented in a manner other than that described. These descriptions are intended to be illustrative rather than restrictive. Therefore, it will be apparent to those skilled in the art that modifications may be made to the disclosed content described without departing from the scope of the claims set forth below.

[0210] It should be understood that the "Detailed Description" section (rather than the "Summary" and "Abstract" sections) is intended to be used to interpret the claims. The "Summary" and "Abstract" sections may set forth one or more but not all exemplary embodiments of the present disclosure as contemplated by one or more inventors, and thus are not intended to limit the present disclosure and the appended claims in any way.

[0211] The present disclosure has been described above with the aid of functional building blocks that illustrate the implementation of specific functions and their relationships. For ease of description, the boundaries of these functional building blocks have been arbitrarily defined here. Alternative boundaries may be defined as long as the specified functions and their relationships are properly performed.

[0212] The above description of specific embodiments will reveal the general nature of the present disclosure so fully that others can easily modify and / or adapt various applications, such as specific embodiments, by applying knowledge within the art without undue experimentation and without departing from the general concepts of the present disclosure. Therefore, based on the teachings and guidance presented herein, such modifications and variations are intended to be within the meaning and range of equivalents of the disclosed embodiments.

[0213] The breadth and scope of the protected subject matter should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. A measurement system, comprising: An illumination system located on a substrate, the illumination system being configured to generate a radiation beam and comprising: first and second sources configured to generate respective different first and second wavelength bands, and first and second resonators optically coupled to respective ones of the first and second sources and configured to narrow respective ones of the first and second wavelength bands; an optical element configured to direct the beam toward a target structure; and A detector is configured to receive radiation returned from the target structure and to generate a measurement signal based on the received radiation.

2. The measurement system according to claim 1, wherein: The illumination system is further configured to adjust respective narrowed wavelength bands of the first and second wavelength bands based on adjustment of a resonant wavelength of respective ones of the first and second resonators.

3. The measurement system according to claim 1, wherein: The first wavelength band and the second wavelength band include shared wavelengths.

4. The measurement system according to claim 1, wherein: The illumination system is further configured to operate within a wide wavelength range of 200 nm to 2000 nm, and to select at least one of the corresponding narrowed wavelength bands of the first and second wavelength bands from the wide wavelength range.

5. The measurement system according to claim 1, wherein: At least one of the corresponding narrowed wavelength bands in the first and second wavelength bands is 20 nm wide or less.

6. The measurement system according to claim 1, wherein: At least one of the corresponding narrowed wavelength bands in the first and second wavelength bands is 1 nm wide or less.

7. The measurement system of claim 1, wherein: The illumination system is further configured to adjust a width of at least one of the corresponding narrowed wavelength bands of the first and second wavelength bands based on modulation of one or more characteristics of the corresponding resonator of the first and second resonators; and The one or more characteristics include at least one of a resonant wavelength and a Q factor.

8. The measurement system according to claim 1, wherein: The irradiation system further comprises: a third source configured to generate a third wavelength band of the beam different from the first and second wavelength bands; and A third resonator is optically coupled to the third source device and is configured to narrow the third wavelength band.

9. The measurement system according to claim 1, wherein: The first source is configured to be unpowered or to have an inhibited output when the second source is powered.

10. The measurement system according to claim 1, wherein: The substrate further comprises: A multiplexer element is configured to direct radiation corresponding to the first wavelength band and radiation corresponding to the second wavelength band along a shared optical axis.

11. The measurement system according to claim 1, wherein: The illumination system further includes an illumination monitor configured to monitor one or more characteristics of the beam, and the illumination system is further configured to send a portion of the beam to the illumination monitor.

12. The measurement system according to claim 11, wherein: The one or more characteristics include at least one of dose, position, intensity, polarization, spectral bandwidth, and wavelength.

13. The measurement system of claim 11, wherein: At least the first source and the first resonator are further configured to form a feedback loop; The irradiance monitor is further configured to monitor radiation in the feedback loop; and The illumination system is further configured to stabilize characteristics of the beam based on the monitored radiation in the feedback loop.

14. The measurement system according to claim 11, wherein: The irradiation monitor is integrated on the substrate.

15. The measurement system of claim 1, wherein: At least a portion of the illumination system includes an integrated photonic device including at least the first source and the first resonator.

16. The measurement system of claim 1, wherein: The measuring system has a diameter of less than 2000 mm 2 , 1000 mm 2 , 500 mm 2 , 100 mm 2 , 50 mm 2 , 25 mm 2 or 16 mm 2 occupied area.

17. The measurement system of claim 1, wherein: The detector comprises an image capture device.

18. The measurement system of claim 1, wherein: Each of the first source and the second source comprises a superluminescent diode.

19. The measurement system of claim 1, wherein: Each of the first and second resonators includes a ring resonator.

20. The measurement system of claim 1, wherein: The irradiation system: further comprising a first polarizer; and Further configured to adjust the polarization of the beam based on user input.

21. The measurement system of claim 20, wherein: The illumination system further includes a second polarizer associated with an optical path of the second source; the first polarizer being associated with an optical path of the first source; and The illumination system is further configured to select at least one of an optical path of the first source and an optical path of a second source.

22. The measurement system of claim 1, wherein: At least one of the first source, the second source, the first resonator, and the second resonator is modular.

23. The measurement system of claim 1, further comprising: a second illumination system located on the second substrate, the second illumination system being configured to generate a second radiation beam and comprising: first and second sources configured to generate respective different first and second wavelength bands of said second radiation beam, and first and second resonators optically coupled to respective ones of the first and second sources of the second illumination system and configured to narrow respective ones of the first and second wavelength bands of the second radiation beam; a second optical element configured to direct the second radiation beam toward a second target structure; and A second detector is configured to receive radiation from the second target structure and to generate a measurement signal based on the received radiation.

24. The measurement system of claim 1, further comprising: an additional illumination system located on a corresponding additional substrate, the additional illumination system being configured to generate a corresponding radiation beam and comprising: corresponding first and second sources configured to generate respective different first and second wavelength bands of the corresponding radiation beam, and a corresponding first and second resonator optically coupled to a corresponding one of the corresponding first and second sources and configured to narrow a corresponding one of the first and second wavelength bands of the corresponding radiation beam; an additional optical element configured to direct the corresponding radiation beam toward a corresponding target structure; and An additional detector is configured to receive radiation from the corresponding target structure and to generate a corresponding measurement signal based on the received radiation scattered by the corresponding target structure.

25. A lithographic apparatus comprising: an illumination device configured to illuminate the pattern forming device with a pattern; a projection system configured to project an image of the pattern onto a target substrate; and A measurement system, the measurement system comprising: An illumination system located on a substrate, the illumination system being configured to generate a radiation beam and comprising: first and second sources configured to generate respective different first and second wavelength bands, and first and second resonators optically coupled to respective ones of the first and second sources and configured to narrow respective ones of the first and second wavelength bands; an optical element configured to direct the beam toward a target structure; and A detector is configured to receive radiation from the target structure and to generate a measurement signal based on the received radiation.

26. A measurement method, comprising: generating a radiation beam using an illumination system located on the substrate, the illumination system comprising first and second sources and first and second resonators; generating a first wavelength band of the beam using the first source; generating a second wavelength band of the beam using the second source, the second wavelength band being different from the first wavelength band; narrowing the first wavelength band using the first resonator; narrowing the second wavelength band using the second resonator; directing the beam toward a target structure; receiving radiation from the target structure using a detector; as well as A measurement signal is generated based on the received radiation using the detector.

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