Stable light source system and method

Abstract

A stable light source configured for spectrally matched and equivalent intensity radiation with multiple outputs is described. This light source comprises a first splitter configured to receive input radiation and split it into a first transmission and reflection portion; a second splitter configured to receive each of the first transmission and reflection portions and further split them into a second transmission and reflection portion; and a combiner configured to combine the second transmission and reflection portions to produce different outputs with mixed transmission and reflection portions. The mixed transmission and reflection portions are configured such that the multiple outputs together form spectrally matched and equivalent intensity radiation. This may be used, for example, to calibrate high-precision detectors and / or for other purposes. An integrating sphere may be included (e.g., instead of and / or in addition to the splitters and combiners).

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims priority to U.S. Application No. 63 / 531,536, filed on August 8, 2023, which are hereby incorporated by reference in their entirety.

[0002] [Technical Field] The present invention relates to stable light source systems and methods.

Background Art

[0003] A lithographic projection apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A patterning device (e.g., a mask) can contain or provide a pattern corresponding to an individual layer of an IC ("design layout"), and this pattern can be transferred to a target portion (e.g., including one or more dies) on a substrate (e.g., a silicon wafer) coated with a layer of radiation - sensitive material ("resist") by methods such as irradiating the target portion through the pattern on the patterning device. Generally, a single substrate contains a plurality of adjacent target portions to which the pattern is successively transferred, one target portion at a time, by a lithographic projection apparatus. In one type of lithographic projection apparatus, the pattern of the entire patterning device is transferred to one target portion in one operation. Such an apparatus is generally called a stepper. In an alternative apparatus (generally called a step - and - scan apparatus), the projection beam scans over the patterning device in a predetermined reference direction ("scan" direction), while simultaneously moving the substrate parallel or antiparallel to this reference direction. Different portions of the pattern on the patterning device are gradually transferred to one target portion.

[0004] Before transferring the pattern from the patterning device to the substrate, the substrate may undergo various procedures such as priming, resist coating, and soft baking. After exposure, the substrate may undergo other procedures ("post-exposure procedures") such as post-bake (PEB), development, hard baking, and measurement / inspection of the transferred pattern. These numerous procedures are used as a basis for creating the individual layers of a device, such as an IC. The substrate may then undergo various processes such as etching, ion implantation (doping), metallization, oxidation, and chemical mechanical polishing (all intended to finish the individual layers of the device). If several layers are required for the device, the entire procedure or a variation thereof is repeated for each layer. Finally, the device is present in each target area on the substrate. These devices are then separated from each other by techniques such as dicing or sawing, so that the individual devices can be mounted on a carrier, connected to pins, etc.

[0005] This device manufacturing process can be considered a patterning process. The patterning process includes a patterning step such as optical and / or nanoimprint lithography using a patterning device in a lithography apparatus to transfer a pattern on a patterning device to a substrate, and generally (but optionally) includes one or more related pattern processing steps such as resist development using a developing apparatus, baking of the substrate using a baking tool, and etching using a pattern using an etching apparatus.

[0006] As semiconductor manufacturing processes continue to advance, the dimensions of functional elements continue to shrink, and the number of functional elements, such as transistors, per device has steadily increased over decades, following a trend commonly known as "Moore's Law." With current technology, layers of devices are manufactured using lithography projection equipment that projects the design layout onto a substrate using illumination from a deep ultraviolet light source, creating individual functional elements with dimensions well below 100 nm, i.e., less than half the wavelength of radiation from the light source.

[0007] The process of printing features smaller in dimensions than the conventional resolution limits of a lithography projector is generally known as low-k1 lithography, following the resolution formula CD = k1 × λ / NA. Here, λ is the wavelength of the radiation used (currently, in most cases, 248 nm or 193 nm), NA is the numerical aperture of the projection optics of the lithography projector, CD is the "limiting dimension" (generally the smallest feature size to be printed), and k1 is the empirical resolution factor. Generally, the smaller k1, the more difficult it becomes to reproduce a pattern on the substrate that resembles the shape and dimensions planned by the designer to achieve a particular electrical function and performance. To overcome these difficulties, advanced fine-tuning steps are applied to the lithography projector, design layout, or patterning device. These include, but are not limited to, optimizing the NA and optical coherence settings, customized lighting schemes, using phase-shift patterning devices, optical proximity effect correction in the design layout (also known as OPC "optical and process correction"), or other methods generally defined as "resolution enhancement techniques" (RET). Measurement is an essential part of these fine-tuning steps. [Overview of the project]

[0008] A stable light source system is described. This system is configured to output spectrally matched and equivalent intensity radiation. In some embodiments, the system is configured for multiple outputs of spectrally matched and equivalent intensity radiation. The system includes a first splitter configured to receive input radiation and split it into a first transmission portion and a reflection portion; a second splitter configured to receive each of the first transmission portion and the reflection portion and further split them into a second transmission portion and a reflection portion; and one or more combiners configured to combine the second transmission portion and the reflection portion to produce different outputs having mixed transmission and reflection portions. The mixed transmission and reflection portions are configured such that the multiple outputs together form spectrally matched and equivalent intensity radiation. This spectrally matched and equivalent intensity radiation (e.g., more stable radiation) can be used to calibrate high-precision detectors and / or for other purposes. As an example, these high-precision detectors can be used in alignment sensors for semiconductor manufacturing and / or for other purposes. In some embodiments, an integrating sphere may be included (for example, instead of and / or in addition to splitters and combiners).

[0009] According to one embodiment, a system is provided configured to output spectrally matched radiation of equivalent intensity. The system comprises a first splitter configured to receive input radiation and split it into a first transmission portion and a reflection portion. The system comprises a second splitter configured to receive each of the first transmission portion and the reflection portion and further split them into a second transmission portion and a reflection portion. The system comprises one or more combiners configured to combine the second transmission portion and the reflection portion to produce different outputs having mixed transmission and reflection portions. The mixed transmission and reflection portions are configured such that the outputs from the system together form spectrally matched radiation of equivalent intensity.

[0010] In some embodiments, the system further comprises optical fibers configured to provide optical paths for optically coupling a first splitter, a second splitter, and one or more combiners. In some embodiments, the system further comprises spatial optical components configured to provide optical paths for optically coupling a first splitter, a second splitter, and one or more combiners. In some embodiments, these optical paths have the same path length and are spectrally matched.

[0011] In some embodiments, different outputs having mixed transparent and reflective portions comprise an equal number of transparent and reflective portions overall. In some embodiments, different outputs comprise different mixtures (combinations) of transparent and reflective portions.

[0012] In some embodiments, one of the combiners comprises a 2x2 optical coupler. In some embodiments, the first splitter comprises a 1x2 optical splitter. In some embodiments, the second splitter each comprises a 1x2 optical splitter. In some embodiments, the second splitter comprises two 1x2 optical splitters. In some embodiments, the second splitter comprises three 1x2 optical splitters. In some embodiments, the second splitter comprises ten 1x2 optical splitters.

[0013] In some embodiments, the system further comprises a radiation source configured to generate input radiation. In some embodiments, the system further comprises one or more isolators configured to receive input radiation from the radiation source and reduce back reflections by ensuring that photons propagate in only one direction. In some embodiments, the system further comprises one or more variable optical attenuators and / or ND filters configured to reduce the power level of the input radiation before the input radiation is provided to a first splitter.

[0014] In some embodiments, the input radiation has a wavelength between approximately 400 nm and approximately 1600 nm and comprises visible light or infrared light.

[0015] In some embodiments, spectrally matched and equivalent intensity radiation is configured to be used to calibrate the detector. In some embodiments, the detector comprises a multi-channel circuit board using one or more photodetectors configured to convert intensity channel optical signals into electrical signals. In some embodiments, the detector is associated with semiconductor measurement.

[0016] In some embodiments, the spectrally matched and equivalent intensity radiation output is configured for lithography, alignment measurements, and / or overlay measurements related to semiconductor manufacturing processes.

[0017] According to another embodiment, a system is provided configured to output spectrally matched radiation of equivalent intensity. The system comprises a radiation source configured to generate radiation and an integrating sphere. The integrating sphere has mixed transmitted and reflected portions configured to receive radiation from the radiation source and flatten the intensity profile of the radiation so that one or more outputs from the integrating sphere combine to form spectrally matched radiation of equivalent intensity.

[0018] In some embodiments, the system includes a filter configured to filter the infrared (IR) portion of radiation from a radiation source in order to reduce or eliminate thermal heating of the system.

[0019] In some embodiments, the radiation source comprises a white light source with a wavelength of 500 to 900 nm.

[0020] In some embodiments, one or more outputs comprise a plurality of output ports, and each output port comprises (as one of many possible examples) a 200 μm multimode fiber. In some embodiments, the plurality of output ports comprises eight output ports. In some embodiments, each multimode fiber has a numerical aperture equal to (also as one of many possible examples) 0.22.

[0021] In some embodiments, the radiation source comprises an attenuator configured to be adjusted to achieve different powers at the output ports of the multimode fibers.

[0022] In some embodiments, the radiation source comprises a spectral filter configured to filter the radiation to provide a particular spectrum of radiation to the integrating sphere.

[0023] In some embodiments, the integrating sphere comprises one or more baffles inside it. The one or more baffles are configured to prevent a direct light path from the input to the integrating sphere to one or more outputs.

[0024] In some embodiments, a photonic crystal fiber is configured to propagate radiation from the radiation source to the integrating sphere.

[0025] According to another embodiment, one or more methods are provided for outputting spectrally matched and equally intense radiation. The one or more methods comprise one or more steps performed by the system described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above aspects and other aspects and features will become apparent to those skilled in the art by considering the following description of specific embodiments in conjunction with the accompanying drawings.

[0027] [Figure 1] FIG. schematically shows a lithographic apparatus according to an embodiment.

[0028] [Figure 2] It is a diagram schematically showing an embodiment of a lithography cell or cluster according to an embodiment.

[0029] [Figure 3] It is a diagram schematically showing an example of an inspection system according to an embodiment.

[0030] [Figure 4] It is a diagram schematically showing an example of a measurement technique according to an embodiment.

[0031] [Figure 5] It is a diagram showing the relationship between a radiation irradiation spot and a measurement target of an inspection system according to an embodiment.

[0032] [Figure 6] It is a diagram showing the optical splitting of radiation from a single radiation source for providing a plurality of output channels that can be used to calibrate a detector according to an embodiment, and a graph showing the transmittance as a function of the input light wavelength for the splitting.

[0033] [Figure 7] It is a diagram showing an exemplary embodiment of a system configured to output radiation with a matched spectrum and equivalent intensity according to an embodiment.

[0034] [Figure 8] It is a diagram showing another exemplary embodiment of a system configured to output radiation with a matched spectrum and equivalent intensity according to an embodiment.

[0035] [Figure 9] It is a diagram showing yet another exemplary embodiment of a system configured to output radiation with a matched spectrum and equivalent intensity according to an embodiment.

[0036] [Figure 10]This figure shows the formula for defining the stability of the radiation source according to the embodiment.

[0037] [Figure 11] This figure shows yet another exemplary embodiment of a system configured to emit spectrally matched and equivalent intensity radiation according to the embodiment.

[0038] [Figure 12] This figure shows a method according to an embodiment for outputting spectrally matched and equivalent intensity radiation.

[0039] [Figure 13] This is a block diagram of an exemplary computer system according to the embodiment. [Modes for carrying out the invention]

[0040] In semiconductor device manufacturing, measurement operations typically involve determining the location of measurement marks (or groups of marks) and / or other targets within the layers of the semiconductor device structure. This location is usually determined by irradiating the measurement marks with radiation and comparing the characteristics of different diffraction orders of the radiation reflected from the marks. Such techniques are used to measure alignment, overlay, and / or other parameters and require highly accurate and precisely calibrated detectors.

[0041] Different radiation phase channels, combined with extracted intensity channel information, are used to characterize the asymmetry of the mark. The radiation intensity channel signals are steady-state and unmodulated. For the asymmetry of the mark to be measured using these intensity channel signals, very small intensity differences must be detectable. This means that the detector must be calibrated with different gain settings using an extremely stable light source.

[0042] Optical splitting of radiation from a light source is a known approach for providing output to multiple channels from a single radiation source. However, the spectral splitting characteristics of a typical 1x4 optical splitter result in differences in the splitting ratio of output power, for example, a range of 20-30% across the four outputs rather than the preferred 25% for each output (at a given wavelength). When a wider wavelength range is required, this output variability (range) can become an even greater problem.

[0043] Advantageously, this system and method employ strategic splice or splitting points and strategic recombination to spectrally flatten the input radiation from the radiation source (e.g., in terms of power and wavelength). Additional optical fiber elements (e.g., isolators, variable optical attenuators, and / or ND (neutral density) filters), spatial optics, and / or other components) are incorporated as needed to achieve extremely stable output across the desired output dynamic range. This technique can generate wide dynamic range outputs with inter-channel power ratio stability of less than ±100 ppm over the four hours required for calibration. While calibration is discussed throughout this specification as one application example of the system and method described, it should be noted that many other applications where a stable light source is desired are also envisioned.

[0044] In short, the following description concerns the manufacturing and patterning processes of semiconductor devices. The following paragraphs also describe some components of systems and / or methods for measuring semiconductor devices. These systems and methods can be used, for example, for measurements such as alignment and overlay, or other operations in the semiconductor device manufacturing process.

[0045] While this description specifically refers to the manufacturing of integrated circuits (ICs) for semiconductor devices, it should be understood that this description has many other applications. For example, this description can be used to manufacture integrated optical systems, induction and detection patterns for magnetic domain memory, liquid crystal display panels, thin-film magnetic heads, and more. Those skilled in the art will understand that in the context of such alternative applications, the terms “reticle,” “wafer,” and “die” used in this text are interchangeable with the more general terms “mask,” “substrate,” and “target portion,” respectively.

[0046] The term “projection optics” should be interpreted broadly to encompass various types of optical systems, including, for example, refractive optics, reflective optics, diaphragms, and reflector-refractor optics. The term “projection optics” also includes components that operate according to any of these design types, collectively or individually, to direct, shape, or control the projected beam of radiation. The term “projection optics” can include any optical components within a lithography projection apparatus, regardless of where the optical components are located in the optical path of the lithography projection apparatus. Projection optics include optical components for shaping, adjusting, and / or projecting radiation from a radiation source before the radiation passes through a patterning device, and / or optical components for shaping, adjusting, and / or projecting radiation after the radiation has passed through a patterning device. Projection optics generally do not include the radiation source and patterning device.

[0047] Figure 1 schematically shows an embodiment of a lithography apparatus LA. This apparatus includes an illumination system (illuminator) IL configured to adjust a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation), a support structure (e.g., mask table) MT constructed to support a patterning device (e.g., mask) MA and connected to a first positioner PM configured to precisely position the patterning device according to specific parameters, a substrate table (e.g., wafer table) WT (e.g., WTa, WTb or both) configured to hold a substrate (e.g., a resist-coated wafer) W and configured to precisely position the substrate according to specific parameters, and connected to a second positioner PW, and a projection system (e.g., refractive projection lens system) PS configured to project the pattern applied to the radiation beam B by the patterning device MA onto a target portion C of the substrate W (e.g., comprising one or more dies, often called a field). The projection system is supported on a reference frame RF. As shown in the figure, the apparatus is transmissive (e.g., employing a transmissive mask). Alternatively, the apparatus may be reflective (e.g., employing a programmable mirror array or a reflective mask).

[0048] The illumination device IL receives the radiated beam from the radiation source SO. The radiation source and the lithography apparatus may be separate entities, for example, if the radiation source is an excimer laser. In such cases, the radiation source is not considered to form part of the lithography apparatus, and the radiated beam is delivered from the radiation source SO to the illumination device IL with the help of a beam delivery system BD, which includes, for example, appropriate directional mirrors and / or beam expanders. In other cases, for example, if the radiation source is a mercury lamp, the radiation source may be an integral part of the apparatus. The radiation source SO and the illumination device IL, together with the beam delivery system BD as needed, may be called a radiation system.

[0049] The illumination device IL can modify the beam intensity distribution. The illumination device can be positioned to limit the radial range of the radiated beam so that the intensity distribution is non-zero within an annular region within the pupil plane of the illumination device IL. In addition, or alternatively, the illumination device IL can be operated to limit the beam distribution within the pupil plane so that the intensity distribution is non-zero within multiple equally spaced sectors within the pupil plane. The intensity distribution of the radiated beam within the pupil plane of the illumination device IL is sometimes referred to as the illumination mode.

[0050] The illumination device IL may include an adjuster AD configured to adjust the (angle / spatial) intensity distribution of the beam. Generally, at least the outer and / or inner radial ranges (generally referred to as σ outer and σ inner, respectively) of the intensity distribution within the pupil plane of the illumination device can be adjusted. The illumination device IL is operable to change the angular distribution of the beam. For example, the illumination device is operable to change the number and angular range of sectors in the pupil plane where the intensity distribution is non-zero. Different illumination modes can be achieved by adjusting the intensity distribution of the beam in the pupil plane of the illumination device. For example, by limiting the radius and angular range of the intensity distribution in the pupil plane of the illumination device IL, the intensity distribution can have a multipolar distribution, such as a dipole, quadrupole, or hexapole distribution. The desired illumination mode can be obtained, for example, by inserting an optical system that provides that illumination mode into the illumination device IL or by using a spatial light modulator.

[0051] The illumination device IL may be operable to change the polarization of the beam and may be operable to adjust the polarization using an adjuster AD. The polarization state of the radiated beam across the pupil plane of the illumination device IL may be called the polarization mode. By using different polarization modes, greater contrast can be achieved in the image formed on the substrate W. The radiated beam may be unpolarized. Alternatively, the illumination device may be configured to linearly polarize the radiated beam. The polarization direction of the radiated beam may vary across the pupil plane of the illumination device IL. The polarization direction of the radiation may differ in different regions within the pupil plane of the illumination device IL. The polarization state of the radiation may be selected depending on the illumination mode. In the case of a multipole illumination mode, the polarization of each pole of the radiated beam may be approximately perpendicular to the position vector of that pole in the pupil plane of the illumination device IL. For example, in the case of a dipole illumination mode, the radiation may be linearly polarized in a direction approximately perpendicular to the line that bisects the two opposite sectors of the dipole. The radiated beam may be polarized in one of two different orthogonal directions. These may be called the X polarization state and the Y polarization state. In quadrupole illumination mode, the radiation from each pole's sector may be linearly polarized in a direction nearly perpendicular to the line bisecting that sector. This polarization mode is sometimes called XY polarization. Similarly, in hexapole illumination mode, the radiation from each pole's sector may be linearly polarized in a direction nearly perpendicular to the line bisecting that sector. This polarization mode is sometimes called TE polarization.

[0052] Furthermore, the lighting device IL generally includes various other components such as an integrator IN and a capacitor CO. The lighting system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for directing, shaping, or controlling the radiation. Thus, the lighting device provides a tuned radiation beam B having the desired uniformity and intensity distribution in cross-section.

[0053] The support structure MT supports the patterning device depending on the orientation of the patterning device, the design of the lithography apparatus, and other conditions such as whether the patterning device is held in a vacuum environment. The support structure can hold the patterning device using mechanical, vacuum, electrostatic, or other clamping techniques. The support structure may be a fixed or movable frame or table, etc., as needed. The support structure can ensure that the patterning device is in the desired position, for example, relative to the projection system. All terms used herein, “reticle” or “mask,” are considered synonymous with the more general term “patterning device.”

[0054] As used herein, the term “patterning device” should be broadly interpreted to refer to any device that can be used to impart a pattern to a target portion of a substrate. In one embodiment, a patterning device is any device that can be used to impart a radiation beam having a pattern in its cross-section to create a pattern to a target portion of a substrate. It should be noted that the pattern imparted to the radiation beam may not precisely match the desired pattern on the target portion of the substrate, for example, if the pattern includes a phase-shift function or so-called assist function. Generally, the pattern imparted to the radiation beam corresponds to a specific functional layer of a device to be created on the target portion of a device such as an integrated circuit.

[0055] Patterning devices can be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well-known in lithography and come in various types, such as binary, alternating phase shift, and decaying phase shift, as well as various hybrid mask types. An example of a programmable mirror array is a matrix arrangement of small mirrors. Each mirror can be tilted individually to reflect the incident radiation beam in various directions. The tilted mirrors give the radiation beam a pattern, which is then reflected by the mirror matrix.

[0056] The term “projection system” should be interpreted broadly to encompass all types of projection systems, including refractive, reflective, refractorious, magnetic, electromagnetic, electrostatic optics, or any combination thereof, depending on the exposure radiation used or other factors such as the use of immersion solutions or vacuum. Where the term “projection lens” is used herein, it should be considered synonymous with the more general term “projection system.”

[0057] A projection system PS may include multiple optical elements (e.g., lenses) and may further include an adjustment mechanism configured to adjust one or more of the optical elements to correct aberrations (phase changes of the pupil plane across the entire field of view). To achieve this, the adjustment mechanism may be operable to manipulate one or more optical elements (e.g., lenses) in the projection system PS in one or more different ways. The projection system may have a coordinate system in which its optical axis extends in the z direction. The adjustment mechanism may be operable to perform any combination of displacing one or more optical elements, tilting one or more optical elements, and / or deforming one or more optical elements. Displacement of optical elements may be in any direction (x, y, z, or a combination thereof). Tilt of optical elements is usually performed by rotating around the x and / or y axes from a plane perpendicular to the optical axis, but in the case of non-rotationally symmetric aspherical optical elements, rotation may be performed around the z axis. Deformation of optical elements may include low-frequency shapes (e.g., astigmatism) and / or high-frequency shapes (e.g., free-form aspherical). Deformation of an optical element may be performed, for example, by applying force to one or more sides of the optical element using one or more actuators, and / or by heating one or more selected areas of the optical element using one or more heating elements. Generally, it is not possible to adjust the projection system PS to compensate for apodization (changes in transmittance across the pupil plane). A transmittance map of the projection system PS can be used when designing a patterning device (e.g., a mask) MA for a lithography apparatus LA. Using computational lithography techniques, the patterning device MA can be designed to compensate for apodization, at least partially.

[0058] Lithography equipment may be of a type having two or more tables (dual stage) (e.g., two or more substrate tables WTa, WTb, two or more patterning device tables, substrate table WTa, and a dedicated substrate-free table WTb below the projection system, for example to facilitate measurement and / or for cleaning). In such a “multistage” machine, additional tables can be used in parallel, or preparation steps can be performed on one or more tables while one or more other tables are used for exposure. For example, alignment measurements can be performed using an alignment sensor AS, and / or level measurements (height, tilt, etc.) can be performed using a level sensor LS.

[0059] The lithography apparatus may be of a type in which at least a portion of the substrate is covered with a liquid having a relatively high refractive index, such as water, to fill the space between the projection system and the substrate. The immersion liquid can also be applied to other spaces within the lithography apparatus, such as between the patterning device and the projection system. Immersion techniques are well known in the industry as a technique for increasing the numerical aperture of the projection system. As used herein, the term “immersion” does not mean that a structure such as a substrate must be immersed in a liquid, but simply that a liquid is present between the projection system and the substrate during exposure.

[0060] During operation of the lithography apparatus, the radiant beam is regulated and supplied by the illumination system IL. The radiant beam B is incident on a patterning device (e.g., a mask) MA held on a support structure (e.g., a mask table) MT and patterned by the patterning device. After crossing the patterning device MA, the radiant beam B passes through a projection system PS that focuses the beam onto a target portion C of the substrate W. With the help of a second positioner PW and position sensors IF (e.g., an interferometer device, a linear encoder, a 2D encoder, or a capacitive sensor), the substrate table WT can be precisely moved, for example, to position different target portions C within the path of the radiant beam B. Similarly, a first positioner PM and another position sensor (not explicitly shown in Figure 1) can be used, for example, to precisely position the patterning device MA relative to the path of the radiant beam B. After mechanical retrieval from the mask library, or during scanning, movement of the support structure MT can generally be achieved with the help of long-stroke modules (coarse positioning) and short-stroke modules (fine positioning), which are part of the first positioner PM. Similarly, movement of the substrate table WT can be achieved using long-stroke and short-stroke modules, which are part of the second positioner PW. In the case of a stepper (not a scanner), the support structure MT is connected to or fixed only to the short-stroke actuator. The patterning device MA and the substrate W can be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, P2. As shown in the figure, the substrate alignment marks occupy dedicated target areas, but may also be placed in the space between target areas (these are called scribelane alignment marks). Similarly, in situations where multiple dies are provided to the patterning device MA, the patterning device alignment marks can be placed between the dies.

[0061] The illustrated apparatus can be used in at least one of the following modes: In step mode, the support structure MT and substrate table WT are kept essentially stationary, and the pattern applied to the radiation beam is projected onto the target portion C at once (i.e., a single static exposure). The substrate table WT is then shifted in the X and / or Y directions to expose different target portions C. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure. In scan mode, the support structure MT and substrate table WT are scanned synchronously while the pattern applied to the radiation beam is projected onto the target portion C (i.e., a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure MT can be determined by the (reduction) scaling and image inversion characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width of the target portion (non-scan direction) in a single dynamic exposure, while the length of the scan operation determines the height of the target portion (scan direction). In another mode, the support structure MT remains essentially stationary while holding the programmable patterning device, and the substrate table WT moves or scans while the pattern applied to the radiation beam is projected onto the target portion C. In this mode, a pulsed radiation source is typically used, and the programmable patterning device is updated as needed after each movement of the substrate table WT or between consecutive radiation pulses during scanning. This operating mode can be readily applied to maskless lithography utilizing programmable patterning devices such as the type of programmable mirror array mentioned above.

[0062] Combinations and / or variations of the above usage modes, or entirely different usage modes, can also be used.

[0063] The substrate may be processed before or after exposure, for example, with a track (typically a tool for coating a resist layer onto the substrate and developing the exposed resist) or a measuring or inspection tool. Where applicable, the disclosure herein may apply to such substrate processing tools and other substrate processing tools. Furthermore, the substrate may be processed multiple times, for example, to create a multilayer IC, and therefore the term "substrate" as used herein may also refer to a substrate that already contains multiple processed layers.

[0064] As used herein in relation to lithography, the terms “radiation” and “beam” encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., wavelengths of 365, 248, 193, 157, or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., wavelengths in the range of 5–20 nm), as well as particle beams such as ion beams or electron beams.

[0065] The various patterns on or provided by a patterning device may have different process windows, i.e., spaces of processing variables within the specification that generate the pattern. Examples of pattern specifications related to potential systematic defects include checking for necking, line pullback, line thinning, CD, edge placement, overlap, resist top loss, resist undercut, and / or bridging. The process window of a pattern on a patterning device or its area is obtained by merging (e.g., superimposing) the process windows of each individual pattern. The boundary of the process window of a group of patterns includes the boundary of some of the process windows of the individual patterns. In other words, these individual patterns limit the process window of the group of patterns.

[0066] As shown in Figure 2, the lithography apparatus LA also includes equipment that forms part of the lithography cell LC, also called a lithocell or cluster, and performs pre-exposure and post-exposure processes on the substrate. Conventionally, these include one or more spin coaters SC for depositing one or more resist layers, one or more developers for developing the exposed resist, one or more chill plates CH and / or one or more bakeplates BK. A substrate handler, or robot RO, picks up one or more substrates from input / output ports I / O1 and I / O2, moves them between various process equipment, and passes them to the loading bay LB of the lithography apparatus. These devices are collectively called tracks and are controlled by a track control unit TCU. The track control unit TCU itself is controlled by a monitoring and control system SCS, which in turn controls the lithography apparatus via a lithography control unit LACU. Thus, various devices can be operated to maximize throughput and processing efficiency.

[0067] To ensure that substrates exposed by a lithography apparatus are exposed accurately and consistently, and / or to monitor a part of a pattern formation process (e.g., a device manufacturing process) that includes at least one pattern transfer step (e.g., a photolithography step), it is desirable to inspect the substrate or other object and measure or determine one or more properties such as alignment, overlay (e.g., between upper layer structures, or between structures of the same layer provided separately to layers by a dual pattern formation process), line width, critical dimension (CD), focus offset, and material properties. Therefore, manufacturing facilities where a lithocell LC is located typically also include a measurement system to measure part or all of the substrate W (Figure 1) processed in the lithocell, or other objects within the lithocell. The measurement system may be part of the lithocell LC, or for example, part of the lithography apparatus LA (e.g., an alignment sensor AS (Figure 1)).

[0068] One or more measurement parameters may include, for example, alignment, overlay between continuous layers formed in or on the patterned substrate, limit dimensions (CD) of features formed in or on the patterned substrate (e.g., limit line width), focus or focus error of the photolithography step, dose or dose error of the photolithography step, and optical aberration of the photolithography step. This measurement is often performed on one or more dedicated measurement targets provided on the substrate. The measurement can be performed after resist development, before etching, after etching, after deposition, and / or at other points in time.

[0069] There are various techniques for measuring structures formed by patterning processes, including the use of scanning electron microscopes, image-based measurement tools, and / or various specialized tools. High-speed, non-invasive forms of specialized measurement tools direct a radiation beam towards a target on the substrate surface and measure the properties of the scattered (diffracted / reflected) beam. By evaluating one or more properties of the radiation scattered by the substrate, one or more properties of the substrate can be determined. Traditionally, this is called diffraction-based measurement. Applications of this diffraction-based measurement include alignment and overlay measurements. For example, alignment and / or overlay can be measured by comparing portions of the diffraction spectrum (e.g., comparing different diffraction orders of the diffraction spectrum of a periodic grating).

[0070] Therefore, in device manufacturing processes (e.g., patterning or lithography processes), various types of measurements may be performed on the substrate or other objects during or after the process. Measurements can be used to determine whether a particular substrate is defective, to adjust the process and the equipment used in the process (e.g., aligning two layers on a substrate or aligning a patterning device to a substrate), to measure the performance of the process and equipment, or for other purposes. Examples of measurements include optical imaging (e.g., optical microscopy), non-imaging optical measurements (e.g., diffraction-based measurements such as ASML Orion measurement tools, ASML YieldStar measurement tools, and ASML SMASH measurement systems), mechanical measurements (e.g., stylus profiling, atomic force microscopy (AFM)), and / or non-optical imaging (e.g., scanning electron microscopy (SEM)).

[0071] Measurement results can be provided directly or indirectly to the monitoring and control system (SCS). If an error is detected, adjustments can be made to the exposure of subsequent substrates (especially if inspection can be performed immediately and one or more other substrates in the batch have not yet been exposed) and / or to the subsequent exposure of exposed substrates. Alternatively, already exposed substrates can be stripped and reprocessed to improve yield, or discarded, to prevent further processing of substrates known to be defective. If defects are present only in a portion of the target area of ​​the substrate, further exposure can be performed only on the target area that meets the specifications. Other manufacturing process adjustments are also possible.

[0072] The measurement system can be used to determine one or more properties of a substrate structure, particularly how one or more properties of different substrate structures change, or how different layers of the same substrate structure change layer by layer. The measurement system can be integrated into a lithography apparatus (LA) or lithocell (LC), or it can be a standalone device.

[0073] To enable measurement, one or more targets are often specially provided on the substrate. Typically, the targets are specially designed and may include periodic structures. For example, a target on the substrate may include one or more one-dimensional periodic structures (e.g., geometric features such as a grid), and after development, the periodic structural features are printed so that they are formed by solid resist lines. As another example, a target may include one or more two-dimensional periodic structures (e.g., a grid), and after development, the periodic structures are printed so that they are formed by solid resist pillars or vias in the resist. The bars, pillars, or vias may be etched into the substrate (e.g., one or more layers on the substrate).

[0074] Figure 3 shows an example of a measurement (inspection) system 10 that can be used to perform alignment, overlay detection, and / or other measurement operations. The system includes a radiation source or illumination source 2 that projects or irradiates radiation onto a substrate W (e.g., a substrate containing measurement marks). The redirected radiation is passed to a sensor and / or other sensor, such as a spectrometer detector 4, to measure the spectrum (intensity as a function of wavelength) of the specularly reflected and / or diffracted radiation, as shown in the graph on the left side of Figure 4. The sensor can generate a measurement signal that transmits measurement data indicating the characteristics of the reflected radiation. From this data, the structure or profile that gives rise to the detected spectrum can be reconstructed by one or more processors PRO or other operations, as generalized examples are shown in Figure 4.

[0075] Similar to the lithography apparatus LA in Figure 1, one or more substrate tables (not shown in Figure 4) may be provided to hold the substrate W during the measurement operation. One or more substrate tables may be similar in shape to or identical to the substrate table WT (WTa or WTb, or both) in Figure 1. In examples where the inspection system 10 is integrated with the lithography apparatus, they may be the same substrate table. Coarse and fine positioners may be provided and configured to precisely position the substrate relative to the measurement optical system. Various sensors and actuators may be provided, for example, to acquire the position of the target portion of the structure (e.g., measurement mark) and position it below the objective lens. Typically, many measurements are performed on the target portion of the structure at various locations on the substrate W. The substrate support may be moved in the X and Y directions to acquire various targets and in the Z direction to acquire the desired position of the target portion relative to the focal point of the optical system. For example, if the optical system is actually substantially stationary (usually in the X and Y directions, and possibly the Z direction) while the substrate moves, it is convenient to think about and describe the operation as if the objective lens were moved to different positions relative to the substrate. Assuming the relative positions of the substrate and the optical system are correct, in principle, it doesn't matter which one is moving, or if both are moving, or if a part of the optical system is moving (e.g., in the Z direction and / or tilt direction) while the rest of the optical system is stationary and the substrate is moving (e.g., in the X and Y directions, and possibly in the Z direction and / or tilt direction).

[0076] In a typical measurement case, the target (part) 30 on the substrate W is a one-dimensional grid and is printed so that after development, the bars are formed of solid resist lines (e.g., covered by a deposited layer) and / or other materials. Alternatively, the target 30 is a two-dimensional grid and is printed so that after development, the grid is formed of solid resist pillars and / or other features within the resist.

[0077] Bars, pillars, vias, and / or other features are etched into or on the substrate (e.g., in one or more layers on the substrate), deposited on the substrate, covered by a deposited layer, and / or have other properties. The target (part) 30 (e.g., bars, pillars, vias, etc.) is sensitive to changes in the patterning process (e.g., optical aberrations, focus changes, dose changes, etc., of a lithography projection device such as a projection system), and changes in the process manifest as changes in the target 30. Thus, measurement data from the target 30 can be used to determine adjustments to one or more manufacturing processes or as a basis for making actual adjustments.

[0078] For example, measurement data from target 30 can indicate the alignment of the layers of a semiconductor device. The measurement data from target 30 can be used (e.g., by one or more processors PRO and / or other processors) to determine one or more semiconductor device manufacturing process parameters based on the alignment, and to determine the adjustments to the semiconductor device manufacturing equipment based on the determined one or more semiconductor device manufacturing process parameters. In some embodiments, this may include, for example, adjusting the stage position, or determining adjustments to the mask design, measurement target design, semiconductor device design, radiation intensity, radiation incidence angle, radiation wavelength, pupil size and / or shape, resist material, and / or other process parameters.

[0079] Figure 5 shows a plan view of a typical target (e.g., a measurement mark) 30 in the system of Figure 4, and the range of a typical irradiated spot S. In some embodiments, the target 30 is a periodic structure (e.g., a grating) that is larger than the width (e.g., diameter) of the irradiated spot S, in order to obtain a diffraction spectrum that is not affected by interference from the surrounding structure. The width of the spot S may be smaller than the width and length of the target. In other words, the target is "underfilled" by the illumination, and the diffraction signal does not essentially contain signals from product features or other elements outside the target itself. The illumination arrangement may be configured, for example, to provide illumination of uniform intensity across the entire back focal plane of the objective lens. Alternatively, illumination may be restricted in an on-axis or off-axis direction, for example, by including an aperture in the illumination path.

[0080] Figure 6 illustrates the optical splitting 600 of radiation 601 from a single radiation source 602 to provide multiple output channels 604, 606, 608, and 610. These multiple output channels can be used to calibrate a detector, such as the detector 4 shown in Figure 3. The splitting 600 is achieved by a series of 1×2 optical splitters 620, which together constitute a 1×4 optical splitter (the input of one radiation 601 is split into four output channels 604-610 by a cascaded arrangement of 1×2 splitters). However, the spectral splitting characteristics of a typical 1×4 optical splitter result in variations in the splitting ratio of the output power, for example, ranging from 20-30% of the output power for all four outputs combined, rather than the preferred 25% for each output. Furthermore, the spectral splitting characteristics often vary based on the wavelength of the input radiation from the radiation source 602. Therefore, this output range (variability) can become an even greater problem when a wider wavelength range is desired. Furthermore, the split 600 may be based on spatially splitting the beam of a superluminescent diode (SLD) into four multimode fibers housed in a fiber bundle. Such solutions are not only difficult to set up but are also highly sensitive to environmental variables such as temperature, relative humidity, atmospheric pressure, and vibration. Figure 6 also illustrates Graph 650, which shows the transmittance (power) 652 as a function of the input optical wavelength 654 for the split 600. Graph 650 shows a non-uniform splitter ratio ranging from 26% to 24% (for output channels 604, 606, 608, and 610) as a function of the input wavelength over the range of 850 nm ± 10 nm.

[0081] Figure 7 shows an exemplary embodiment of System 700 configured to output spectrally matched and equivalent intensity radiation 701. As shown in Figure 7, System 700 is configured to output multiple spectrally matched and equivalent intensity synchrotron radiation. System 700 provides a novel optical design architecture. System 700 includes a first splitter 702 configured to receive input radiation 703 from a radiation source 705 and split it into a first transmission portion 710 and a reflection portion 712, respectively. The input radiation 703 may have wavelengths between, for example, about 400 nm and about 1600 nm. The input radiation 703 may include visible light, infrared light, near-infrared light, and / or other radiation.

[0082] System 700 includes a second splitter 704 configured to receive the first transmission portion 710 and reflection portion 712, respectively, and further split them into a second transmission portion and reflection portion 714, 716, 718, and 720. System 700 includes one or more combiners 706 configured to combine the second transmission portion and reflection portion 714-720 to produce different outputs 730, 732, 734, and 736, which are mixed transmission and reflection portions. Figure 7 shows four outputs (channels) as an example. The number of outputs may be more or less. The mixed transmission and reflection portions are configured such that the outputs 730-736 from System 700 together form spectrally matched and equivalent intensity radiation. For example, spectrally matched and equivalent intensity radiation may have a wavelength of approximately 850 nm, and the intensity of the radiation from each output 730-736 may be approximately the same.

[0083] In some embodiments, as shown in the example in Figure 7, one combiner 706 (or mixer) of one or more combiners comprises a 2x2 optical coupler. The first splitter 702 may comprise a 1x2 optical splitter. The second splitter 704 may each comprise a 1x2 optical splitter, where the second splitter comprises two 1x2 optical splitters. In some embodiments, the splitters and combiners described herein comprise multiple instances of the same (or similar) product, such as 1x2 or 2x2 fiber couplers. The splitters and / or couplers may comprise fiber fusion splice couplers / splitters, such as fusion splice fiber couplers / splitters, where two fibers are essentially fused together to form a 1x2 coupler, and / or other splitters / couplers. This can be thought of, for example, as a fiber version of a spatially unpolarized beam splitter, or the entire configuration can be implemented as an integrated optical device.

[0084] In some embodiments, spectrally matched and equivalent intensity radiation may be used, for example, to calibrate a detector that uses a photodetector to convert an intensity channel optical signal into an electrical signal (such as detector 4 shown in Figure 4). In some embodiments, the detector comprises a multi-channel circuit board using one or more photodetectors, an array of photodetectors or camera devices, and / or other components configured to convert an intensity channel optical signal into an electrical signal. Other applications of spectrally matched and equivalent intensity radiation are also envisioned.

[0085] Figure 7 also illustrates Graph 750, which shows the transmittance (power) 752 as a function of the input optical wavelength 754 for system 700. Graph 750 shows a reduced non-uniform splitter ratio (for outputs 730, 732, 734, and 736) in the range slightly above and slightly below 25% as a function of the input wavelength over the range of 850 nm ± 10 nm. As shown in Graph 750, system 700 extends the flatter portion of transmittance (power) 752 over 850 nm ± 10 nm, which falls within the range of 24.99% to 25.03% compared to 24–26% shown in Figure 6.

[0086] Figure 8 shows another exemplary embodiment of system 800 configured to output spectrally matched and equivalent intensity radiation 801. As shown in Figure 8, system 800 is configured for multi-output spectrally matched and equivalent intensity radiation. System 800 may be similar and / or identical to system 700 in one or more aspects, and as a result, similar or equivalent components share similar or equivalent characteristics. For example, system 800 includes a first splitter 802 configured to receive input radiation 803 from radiation source 805 and split it into a first transmissive portion 810 (where T represents transmissive) and a reflective portion 812 (where R represents reflective), respectively. System 800 includes a second splitter 804 configured to receive the first transmission portion 810 and the reflection portion 812 respectively, and further split them into a second transmission portion and reflection portions 814, 816, 818, 820, 822, and 824 (see various T and R). In this example, the second splitter comprises three 1x2 optical splitters.

[0087] System 800 comprises one or more combiners 806 configured to combine second transmission and reflection portions 814-824 to produce different outputs 830, 832, 834, and 836 (four again in this example) which are mixed transmission and reflection portions. For example, following various T and R through different branching paths of System 800, output 830 comprises T*R. Output 832 comprises (T*T*T)+(R*R*T). Output 834 comprises (T*T*R)+(R*R*R). Output 836 comprises R*T. The mixed transmission and reflection portions (T and R) are configured such that outputs 830-836 from System 800 combine to form spectrally matched radiation of equivalent intensity.

[0088] In some embodiments, different outputs 830-836, which have a mixture of transparent and reflective portions, have the same number of transparent and reflective portions overall. For example, if we count the total number of T and the total number of R in outputs 830-836, we find that they are the same. However, different outputs 830-836 have different mixtures (combinations) of transparent and reflective portions.

[0089] In some embodiments, system 800 (and / or any other embodiments of the system described herein) may comprise optical fibers 850 configured to provide an optical path 852 for optically coupling a first splitter 802, a second splitter 804, and one or more combiners 806. In some embodiments, the optical path 852 may be directly coupled to the corresponding splitters, combiners, and / or other components (e.g., without air or lens space in between). Each optical path may comprise, for example, a waveguide and / or other structure. In some embodiments, system 800 comprises a spatial optical component 854 configured to provide the optical path 852. In this example, the optical path 852 may not be directly coupled to any other component of system 800. In some embodiments, the optical paths 852 have the same path length and the intensity of the radiation 801 is spectrally matched.

[0090] In some embodiments, system 800 (and / or any other embodiments of the systems described herein) may include one or more isolators 880 (two shown in this example) configured to receive input radiation 803 from radiation source 805 and reduce back reflections by ensuring that photons propagate in only one direction. System 800 may also include one or more variable optical attenuators 882 (again two shown in this example), ND filters, and / or other components configured to reduce the power level of input radiation 803 before it is supplied to the first splitter 802.

[0091] Figure 9 illustrates yet another exemplary embodiment of system 900 configured to output spectrally matched and equivalent intensity radiation. As shown in Figure 9, system 900 is configured for multi-output spectrally matched and equivalent intensity radiation. System 900 may be similar and / or identical to system 700 and / or system 800 in one or more aspects, and as a result, similar or equivalent components share similar or equivalent characteristics. For example, system 900 includes a first splitter 902 configured to receive input radiation 903 from radiation source 905 and split it into a first transmission portion 910 and a reflection portion 912, respectively. System 900 includes a second splitter 904 configured to receive the first transmission portion 910 and the reflection portion 912, respectively, and further split them into a second transmission portion and reflection portions 914-952. In this example, the second splitter comprises an instance of the same (or similar) product, such as a 1x2 or 2x2 fiber coupler. In some embodiments, the second splitter 904 may comprise up to 10 or more 1x2 and / or 2x2 optical splitters.

[0092] System 900 comprises one or more combiners 906 configured to combine second transmission and reflection portions 914-952 to produce different outputs 960, 962, 964, 966, 968, 970, 972, and 974 (eight in this example) with mixed transmission and reflection portions. The mixed transmission and reflection portions are configured such that the outputs 960-974 from System 900 together form spectrally matched radiation of equivalent intensity. Again, System 900 (and / or any other embodiment of the system described herein) may comprise optical fibers, spatial optical components, and / or other components (all unindicated in Figure 9) configured to provide an optical path (unindicated in Figure 9 for space reasons) for optically coupling a first splitter 902, a second splitter 904, and one or more combiners 906.

[0093] System 900 (and / or any other embodiment of the system described herein) may also include one or more isolators 980 (two shown in this example) configured to receive input radiation 903 from radiation source 905, one or more variable optical attenuators 982 (again two shown in this example) configured to reduce the power level of input radiation 903 before it is supplied to the first splitter 902, an ND filter, and / or other components, etc. Note that one or more isolators 980, radiation 903, radiation source 905, and / or variable optical attenuators 982 may be similar to and / or identical to the corresponding components in Figure 8 (i.e., one or more isolators 880, radiation 803, radiation source 805, and / or variable optical attenuators 882). The different numbering in Figure 9 is simply to indicate that any of these components (and / or any other components described herein) may be used interchangeably in the multiple embodiments described.

[0094] Tests conducted using one or more of the systems described above (e.g., systems 700, 800, and 900) with four independent detectors (each shown in Figure 3, similar to and / or identical to detector 4 described above) where the incident power varied between 100 μW and 1 nW (this is merely an example range and should not be considered limiting) demonstrated excellent stability across all output channel combinations (approximately 100 ppm (parts per million) over 4 hours). Intensity = Power / Area (Watts / Area). Power = Energy (W).

[0095] Figure 10 shows equation 1000 which defines this stability. Equation 1000 defines the stability (i.e., Ch1 / Ch2) of one channel (Ch) or output (e.g., as described in relation to Figures 7-9 above) relative to another channel. This is analogous to the power percentage output of each channel (Y-axis of each graph) shown, for example, in Figure 6 or Figure 7. As shown in Figure 10, in equation 1000, the term representing the range of the maximum minus minimum ratio of the two channels (this term gives the maximum difference of the ratio of Ch1 / Ch2) is multiplied by 1e6 / 2 (converted to ppm, where / 2 is for + / -, and ultimately becomes ppm). The entire product is then divided by twice the mean of the ratio (the midpoint of the ratio of Ch1 / Ch2).

[0096] Figure 11 illustrates another exemplary embodiment of System 1100 configured to output spectrally matched and equivalent intensity radiation 1101 (e.g., that can be used for calibration and / or other purposes as described herein). As shown in Figure 11, System 1100 is configured for multiple outputs of spectrally matched and equivalent intensity radiation. System 1100 comprises a radiation source 1102 (e.g., which may be similar to and / or identical to one or more other radiation sources described herein), an integrating sphere 1104, and / or other components. Radiation source 1102 is configured to produce radiation 1103. The integrating sphere 1104 is configured to receive radiation 1103 from radiation source 1102 and flatten the intensity profile of radiation 1103. The integrating sphere 1104 is configured such that there is sufficient random scattering around the circumference of the sphere and that at a given output port of the sphere, each unit of the integrated area receives the same radiance / flux. In some embodiments, the filter 1110 is configured to filter the infrared (IR) portion of the radiation 1103 from the radiation source 1102 in order to reduce or eliminate thermal heating of the system 1100 and / or for other purposes. In some embodiments, the filter 1110 is configured to filter the radiation 1103 to provide the radiation 1103 of a specific spectrum to the integrating sphere 1104.

[0097] In some embodiments, the radiation source 1102 comprises a white light source, for example, 500–900 nm. In some embodiments, the integrating sphere 1104 facilitates a further expansion of the wavelength, for example, to 400–2200 nm (Note: This wavelength range is a limitation of the optical fiber itself, not the division mechanism of the integrating sphere). One or more outputs 1106 comprises multiple output ports 1107, each output port 1107 comprising a 200 μm multimode fiber and / or other components. In some embodiments, the multiple output ports 1107 comprises up to eight or more output ports 1107 (however, only three are shown as an example in Figure 11). In some embodiments, each multimode fiber has an numerical aperture equal to 0.22 and / or other characteristics. In some embodiments, the radiation source 1102 comprises an attenuator 1120 configured to be tuned to achieve different powers at the output ports 1107 of the multimode fiber. In some embodiments, a photonic crystal fiber is configured to propagate radiation 1103 from the radiation source 1102 to the integrating sphere 1104.

[0098] In some embodiments, the integrating sphere 1104 includes one or more baffles 1130 inside the integrating sphere 1104. The one or more baffles 1130 are configured, for example, to prevent a direct path of light from the input to the integrating sphere 1104 to one or more outputs 1106 (or output ports 1107).

[0099] Figure 12 shows a method 1200 for outputting spectrally matched and equivalent intensity radiation. In some embodiments, one or more steps of method 1200 may be implemented in, for example, systems 700, 800, and / or 900 illustrated in Figures 7, 8, and 9, respectively, system 10 illustrated in Figure 3, a computer system (e.g., illustrated in Figure 13 and described above), and / or other systems. In some embodiments, method 1200 comprises the steps of generating input radiation (step 1202), receiving input radiation and splitting it into a first transmission portion and a reflection portion (step 1204), receiving each of the first transmission portion and the reflection portion and further splitting them into a second transmission portion and a reflection portion (step 1206), combining the second transmission portion and the reflection portion to obtain a different output with a mixture of transmission and reflection portions (step 1208), calibrating a detector (step 1210), and / or other steps. It should be noted again that calibrating the detector (step 1210) is one example of an application for spectrally matched and equivalent intensity radiation. Other applications are also envisioned, for example, that can reinforce and / or replace the calibration in step 1210.

[0100] The steps of Method 1200 are illustrative. In some embodiments, Method 1200 may be performed with one or more additional steps not described and / or without one or more of the described steps. For example, in some embodiments, Method 1200 may include an additional step relating to determining the adjustment of a measuring detector. Furthermore, the steps of Method 1200 are shown in Figure 12, and the order described herein is not limiting.

[0101] In some embodiments, one or more parts of Method 1200 may be implemented and / or controlled by one or more processing units (e.g., digital processors, analog processors, digital circuits designed to process information, analog circuits designed to process information, state machines, and / or other mechanisms for electronically processing information). One or more processing units may include one or more devices that perform some or all of the steps of Method 1200 in response to instructions electronically stored in an electronic storage medium. One or more processing units may include one or more devices configured by hardware, firmware, and / or software to be specifically designed to perform one or more steps of Method 1200 (see, for example, the description relating to Figure 13 below).

[0102] In step 1202, input radiation is generated. The radiation may have a target wavelength and / or wavelength range, target intensity, and / or other properties. The target wavelength and / or wavelength range, target intensity, etc., may be input and / or selected by the user, determined by the system (e.g., system 10 shown in Figure 3) based on previous measurements, and / or determined in other ways. In some embodiments, the radiation includes light and / or other radiation. In some embodiments, light includes visible light, infrared light, near-infrared light, and / or other light. In some embodiments, the radiation may be any radiation suitable for interferometry. In some embodiments, the wavelength of the input radiation is between approximately 400 nm and approximately 1600 nm (or multiple wavelengths). For example, the input radiation may be visible light. In some embodiments, the input radiation is generated by a single light source configured to generate radiation along a first axis. In some embodiments, step 1202 is performed by a radiation source similar to and / or the same as light source 2 shown in Figure 3.

[0103] In some embodiments, step 1202 includes receiving the input radiation from the radiation source using one or more isolators to reduce back reflections by ensuring that photons propagate in only one direction. Step 1202 may also include reducing the power level of the input radiation using one or more variable optical attenuators and / or ND filters before the input radiation is supplied to the first splitter.

[0104] In step 1204, the input radiation is received (for example, from a radiation source, optionally via one or more isolators, variable optical attenuators, and / or ND filters) and split into a first transmitted portion and a first reflected portion (or channel) using a first splitter. In some embodiments, the input radiation is split into, for example, two or more portions. In some embodiments, step 1204 is performed by splitters identical or similar to the splitters 702, 802, and / or 902 described above and shown in Figures 7, 8, and 9, respectively. For example, in some embodiments, the first splitter comprises a 1×2 optical splitter.

[0105] In step 1206, the first transmitted portion and the reflective portion are each received and further divided into a second transmitted portion and a reflective portion using a second splitter. In some embodiments, the second splitter is similar to and / or identical to the splitters 704, 804, and / or 904 described above and shown in Figures 7, 8, and 9, respectively. For example, in some embodiments, the second splitter comprises each 1×2 optical splitter. In some embodiments, the second splitter comprises two 1×2 optical splitters. In some embodiments, the second splitter comprises three 1×2 optical splitters. In some embodiments, the second splitter comprises up to 10 or more 1×2 optical splitters.

[0106] In step 1208, the second transmission and reflection portions are coupled to different outputs containing a mixture of transmission and reflection portions using one or more combiners. The mixed transmission and reflection portions are configured such that each output together forms spectrally matched radiation of equivalent intensity. In some embodiments, the different outputs with mixed transmission and reflection portions comprise an equal number of transmission and reflection portions as a whole. In some embodiments, the different outputs comprise different mixtures (combinations) of transmission and reflection portions. In some embodiments, step 1208 is performed by one or more combiners identical or similar to combiners 706, 806, and / or 906 described above and shown in Figures 7, 8, and 9, respectively. For example, in some embodiments, one of the one or more combiners comprises a 2×2 optical coupler.

[0107] In some embodiments, the splitter and combiner described above comprises multiple instances of the same (or similar) product, such as a 1x2 or 2x2 fiber coupler.

[0108] In some embodiments, steps 1202, 1204, and / or 1206 include providing optical paths by optical fibers for optically coupling a first splitter, a second splitter, and one or more combiners. In some embodiments, the optical paths may be provided by spatial optical components, for example, having the same path length and being spectrally matched.

[0109] In some embodiments, instead of and / or in addition to steps 1204-1208, method 1200 comprises receiving and planarizing radiation from a radiation source using an integrating sphere so that one or more outputs from the integrating sphere have mixed transmitted and reflected portions configured to combine to form spectrally matched radiation of equivalent intensity (see, for example, Figure 11 and system 1100 described above). This may include filtering the infrared (IR) portion of the radiation from the radiation source using filters to reduce or eliminate thermal heating of the system, tuning attenuators to achieve different powers at the output (e.g., a port) (e.g., a multimode fiber), filtering the radiation using spectral filters to provide a specific spectrum of radiation to the integrating sphere, and / or other steps. In some embodiments, the integrating sphere comprises one or more baffles inside the integrating sphere configured to prevent a direct path of light from the input to the integrating sphere to one or more outputs. In this embodiment, radiation can be propagated from the radiation source to the integrating sphere using, for example, a photonic crystal fiber.

[0110] In step 1210, the detector (e.g., detector 4 shown in Figure 3) is calibrated using spectrally matched and equivalent intensity radiation. This detector may be associated with, for example, semiconductor measurement. In some embodiments, the detector comprises a multi-channel circuit board using one or more photodetectors configured to convert intensity channel optical signals into electrical signals.

[0111] In some embodiments, alignment and / or overlay and / or other measurements may be determined in step 1210. Alignment and / or overlay may be determined based on reflected and diffracted radiation and / or other information from a diffraction grating target. For example, in some embodiments, step 1210 includes illuminating (and / or irradiating) one or more targets (e.g., target 30 shown in Figure 3) in a patterned substrate with radiation. The radiation may be generated by a radiation source (e.g., radiation source 2 shown in Figure 3 above). In some embodiments, the radiation may be directed to multiple targets, a single target, a sub-part of a target (e.g., a part smaller than the whole), and / or in other ways to the substrate. In some embodiments, the radiation may be directed to the target in a time-varying manner. For example, the radiation may be raster-scanned over the target (e.g., by moving the target under the radiation) so that different parts of the target are irradiated at different times. As another example, the characteristics of the radiation (e.g., wavelength, intensity, etc.) may be varied. This may create a time-varying data envelope or window for analysis via a calibrated detector. Data envelopes facilitate the analysis of individual sub-parts of a target, comparisons of parts of a target with other parts and / or other targets (e.g., other layers), and / or other analyses.

[0112] In some embodiments, step 1210 includes generating a measurement signal based on reflected radiation detected from a diffraction grating target using a calibrated detector, as described above. The measurement signal is generated by a calibrated detector (such as detector 4 in Figure 3 and / or other sensors) based on radiation received by the sensor. The measurement signal includes measurement information about the target. For example, the measurement signal may be an alignment and / or overlay signal and / or other measurement signal, which includes alignment and / or overlay measurement information. The measurement information (e.g., alignment values, overlay values ​​and / or other information) can be determined using the principles of interferometry and / or other principles.

[0113] The measurement signal includes an electronic signal representing and / or corresponding to radiation reflected from a target. The measurement signal may indicate, for example, a measured value associated with a diffraction grating target, and / or other information. Generating the measurement signal involves sensing reflected radiation and converting the sensed reflected radiation into an electronic signal. In some embodiments, generating the measurement signal involves sensing different regions and / or different shapes of a target, and / or different portions of reflected radiation from multiple targets, and combining the different portions of reflected radiation to form a measurement signal. This includes generating and / or analyzing one or more images of a target using the radiation described herein. This sensing and conversion may be performed by the detector 4 shown in Figure 3 (e.g., calibrated as part of step 1110) and / or the processor PRO, and / or similar and / or the same components, and / or other components.

[0114] In some embodiments, Method 1200 includes determining adjustments to the semiconductor device manufacturing process. In some embodiments, Method 1200 includes determining one or more semiconductor device manufacturing process parameters. One or more semiconductor device manufacturing process parameters can be determined based on one or more detected phase and / or amplitude variations, overlay and / or alignment values ​​indicated by the measurement signal, and / or other similar systems, and / or other information. One or more parameters include radiation parameters (radiation used for measurement), overlay values, alignment values, measurement inspection positions on layers of the semiconductor device structure, trajectory of the radiation beam across the target, and / or other parameters. In some embodiments, process parameters can be broadly interpreted to include stage position, mask design, measurement target design, semiconductor device design, radiation intensity (used for resist exposure, etc.), radiation incidence angle (used for resist exposure, etc.), radiation wavelength (used for resist exposure, etc.), pupil size and / or shape, resist material, and / or other parameters.

[0115] In some embodiments, Method 1200 includes determining process adjustments based on one or more determined semiconductor device manufacturing process parameters, adjusting semiconductor device manufacturing equipment based on the determined adjustments, and / or other steps. For example, if a determined measurement is not within process tolerance, the out-of-tolerance measurement may be caused by one or more manufacturing processes in which process parameters have drifted and / or otherwise been modified, and as a result, the process may no longer be producing acceptable devices (e.g., the measurement may exceed an tolerance threshold). Based on the measurement determination, one or more new or adjusted process parameters may be determined. The new or adjusted process parameters may be configured so that the manufacturing process again produces acceptable devices.

[0116] For example, a new or adjusted process parameter may adjust a previously unacceptable measurement to an acceptable range. The new or adjusted process parameter may be compared to an existing parameter for a particular process. If there is a difference, that difference may be used, for example, to determine the adjustment of the apparatus used to manufacture the device (for example, parameter "x" should be increased / decreased / changed to match a new or adjusted version of parameter "x" determined as part of method 1200). In some embodiments, method 1200 may include electronically adjusting the apparatus (for example, based on the determined process parameter). Electronically adjusting the apparatus may include, for example, sending electronic signals and / or other communications to the apparatus that result in changes to the apparatus. Electronic adjustment may include, for example, changing the settings of the apparatus and / or other adjustments.

[0117] Figure 13 shows an example of a computer system CS that may be used for and / or to control one or more operations described herein. The computer system CS includes a bus BS or other communication mechanism for communicating information and a processor PRO (or multiple processors similar to and / or the same as the processor PRO shown in Figure 3) connected to the bus BS for processing information. The computer system CS also includes main memory MM, such as random access memory (RAM) or other dynamic storage device connected to the bus BS for storing information and instructions executed by the processor PRO. The main memory MM can also be used to store temporary variables or other intermediate information during the execution of instructions by the processor PRO. The computer system CS also includes read-only memory (ROM) or other static storage device connected to the bus BS for storing static information and instructions of the processor PRO. A storage device SD, such as a magnetic disk or optical disk, is provided and connected to the bus BS for storing information and instructions.

[0118] The computer system CS can be connected via the bus BS to a display DS, such as a flat panel or touch panel display or a cathode ray tube (CRT), to display information to the computer user. Input devices ID, including alphanumeric keys and other keys, are connected to the bus BS to transmit information and command selections to the processor PRO. Another type of user input device is a cursor control CC, such as a mouse, trackball, or cursor arrow keys, which transmits directional information and command selections to the processor PRO and controls the movement of the cursor on the display DS. This input device typically has two degrees of freedom on two axes, a first axis (e.g., x) and a second axis (e.g., y), allowing the device to specify a position in a plane. Touch panel (screen) displays can also be used as input devices.

[0119] In some embodiments, all or part of one or more steps described herein may be executed by a computer system CS in response to a processor PRO executing one or more sequences of one or more instructions contained in main memory MM. Such instructions may be read into main memory MM from another computer-readable medium, such as a storage device SD. By executing the sequence of instructions contained in main memory MM, the processor PRO executes the process steps described herein. One or more processors in a multiprocessing configuration may also be used to execute the sequence of instructions contained in main memory MM. In some embodiments, hardwired circuitry may be used instead of or in combination with software instructions. Therefore, the description herein is not limited to any particular combination of hardware circuitry and software.

[0120] As used herein, the terms “computer-readable medium” or “machine-readable medium” refer to any medium involved in providing instructions to the processor PRO for execution. Such mediums can take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks such as storage devices SD. Volatile media include dynamic memory such as main memory MM. Transmission media include coaxial cables, copper wires, and optical fibers, including wires that make up a bus BS. Transmission media can also take the form of sound waves or light waves generated during radio frequency (RF) and infrared (IR) data communications. Computer-readable media are non-temporary and include, for example, floppy disks, flexible disks, hard disks, magnetic tapes, and other magnetic media, CD-ROMs, DVDs, and other optical media, punch cards, paper tapes, and other physical media with hole patterns, RAM, PROMs, EPROMs, FLASH-EPROMs, and other memory chips or cartridges. Instructions may be recorded on non-temporary computer-readable media. When executed by a computer, these instructions can implement any of the operations described herein. Temporary computer-readable media include, for example, carrier waves and other propagating electromagnetic signals.

[0121] Various forms of computer-readable media may be involved in transporting one or more sequences of one or more instructions to the processor PRO for execution. For example, instructions may initially be held on a magnetic disk on a remote computer. The remote computer can load instructions into dynamic memory and transmit them over a network. A communication interface CI connected to the bus BS can receive signaled data and place it on the bus BS. The bus BS transports the data to the main memory MM, from which the processor PRO retrieves and executes the instructions. Instructions received by the main memory MM can optionally be stored on the storage device SD before or after execution by the processor PRO.

[0122] A communication interface (CI) provides bidirectional data communication connectivity to a network link (NDL) connected to a local network (LAN). For example, a communication interface (CI) could be an Integrated Services Digital Network (ISDN) card or modem providing data communication connectivity to a corresponding type of telephone line. Another example is a local area network (LAN) card providing data communication connectivity to a compatible LAN. Wireless links can also be implemented. In such implementations, the communication interface (CI) sends and receives electrical, electromagnetic, or optical signals carrying digital data streams representing various types of information.

[0123] A network data link (NDL) typically provides data communication to other data devices over one or more networks. For example, a network data link (NDL) can connect to a host computer (HC) via a local network (LAN). This includes data communication services provided over the World Wide Packet Data Communication Network, now commonly referred to as the "Internet" (INT). A local network (LAN) (Internet) can use electrical, electromagnetic, or optical signals to carry digital data streams. Signals transmitted over various networks to and from a computer system (CS), and signals via network data links (NDL) and communication interfaces (CI), are exemplary forms of carrier waves for transmitting information.

[0124] A computer system CS can send messages and receive data, including program code, via a network, a network data link (NDL), and a communication interface (CI). In the example of the internet, a host computer (HC) may send requested code for an application program via the internet (INT), network data link (NDL), local network (LAN), and communication interface (CI). One of the downloaded applications may, for example, provide all or part of the methods described herein. The received code may be executed by the processor (PRO) upon receipt and / or stored in a storage device (SD) or other non-volatile storage for later execution. In this way, the computer system CS may obtain application code in carrier form.

[0125] Various embodiments of the System and Method are disclosed in the following numbered list of items. Further features, characteristics, and exemplary technical solutions of the Disclosure are described below in terms of any combination of items that may be optionally claimed. 1. A system configured to emit spectrally matched and equivalent intensity radiation, A first splitter configured to receive an input radiation and split it into a first transmitted portion and a first reflected portion, A second splitter configured to receive each of the first transmission portion and reflection portion and further divide them into a second transmission portion and reflection portion, The system comprises one or more combiners configured to combine the second transparent and reflective portions to produce different outputs having mixed transparent and reflective portions, A system in which the aforementioned mixed transmission and reflection portions are configured such that the outputs from the system combine to form spectrally matched radiation of equivalent intensity. 2. The system according to item 1, further comprising an optical fiber configured to provide an optical path for optically coupling the first splitter, the second splitter, and the one or more combiners. 3. The system according to any of the preceding sections, further comprising a spatial optical component configured to provide an optical path for optically coupling the first splitter, the second splitter, and the one or more combiners. 4. The system according to any of the preceding items, wherein the optical paths have the same optical path length and are spectrally matched. 5. The system according to any one of items 1 to 4, wherein the different outputs having mixed transmissive and reflective portions comprise an equal number of transmissive and reflective portions in total. 6. The system described in any of the preceding sections, wherein different outputs comprise different mixtures of transmission and reflection portions. 7. The system according to any of the preceding items, wherein one of the one or more combiners comprises a 2x2 optical coupler. 8. The system according to any of the preceding items, wherein the first splitter comprises a 1x2 optical splitter. 9. The system according to any of the preceding items, wherein each of the second splitters comprises a 1x2 optical splitter. 10. The system according to any of the preceding items, wherein the second splitter comprises two 1x2 optical splitters. 11. The system described in any of the preceding sections, wherein the second splitter comprises three 1x2 optical splitters. 12. The system according to any of the preceding items, wherein the second splitter comprises 10 1x2 optical splitters. 13. The system according to any of the preceding paragraphs, further comprising a radiation source configured to generate the input radiation. 14. The system according to any of the preceding clauses, further comprising one or more isolators configured to receive the input radiation from the radiation source and reduce back reflections by ensuring that photons propagate in only one direction. 15. The system according to any of the preceding items, further comprising one or more variable optical attenuators and / or ND filters configured to reduce the power level of the input radiation before the input radiation is provided to the first splitter. 16. The system according to any of the preceding items, wherein the input radiation has a wavelength between approximately 400 nm and approximately 1600 nm and comprises visible light or infrared light. 17. The system described in any of the preceding sections, wherein the spectrally matched and equivalent intensity radiation output is configured to be used to calibrate the detector. 18. The system according to any of the preceding items, comprising a multichannel circuit board using one or more photodetectors configured to convert intensity channel optical signals into electrical signals. 19. The detector is part of any of the preceding sections, and the system is associated with semiconductor measurement. 20. The system described in any of the preceding sections, wherein the spectrally matched and equivalent intensity radiation output is configured for lithography, alignment measurements, and / or overlay measurements related to semiconductor manufacturing processes. 21. A method for outputting spectrally matched and equivalent intensity radiation, A first splitter is used to receive the input radiation and divide it into a first transmitted portion and a reflected portion. A step of receiving the first transmission portion and reflection portion respectively using a second splitter, and further dividing them into a second transmission portion and reflection portion, The process includes a step of combining the second transparent portion and reflective portion using one or more combiners to obtain a different output having a mixture of transparent and reflective portions, A method wherein the mixed transmission and reflection portions are configured such that their outputs combine to form spectrally matched and equivalent intensity radiation. 22. The method of claim 21, further comprising the step of providing an optical path by optical fiber for optically coupling the first splitter, the second splitter, and the one or more combiners. 23. The method according to any of the preceding items, further comprising the step of providing an optical path for optically coupling the first splitter, the second splitter, and the one or more combiners by a spatial optical component. 24. The method according to any of the preceding items, wherein the optical paths have the same optical path length and are spectrally matched. 25. The method according to any of the preceding items, wherein the different outputs having mixed transmissive and reflective portions comprise an equal number of transmissive and reflective portions in total. 26. The method according to any of the preceding items, wherein different outputs comprise different mixtures of transmitted and reflected portions. 27. The method according to any of the preceding items, wherein one of the one or more combiners comprises a 2x2 optical coupler. 28. The method according to any of the preceding items, wherein the first splitter comprises a 1x2 optical splitter. 29. The method according to any of the preceding items, wherein the second splitter comprises a 1x2 optical splitter. 30. The method according to any of the preceding items, wherein the second splitter comprises two 1x2 optical splitters. 31. The method according to any of the preceding items, wherein the second splitter comprises three 1x2 optical splitters. 32. The method according to any of the preceding items, wherein the second splitter comprises 10 1x2 optical splitters. 33. The method according to any of the preceding items, further comprising the step of generating the input radiation using a radiation source. 34. The method according to any of the preceding items, further comprising the step of using one or more isolators to receive the input radiation from the radiation source and to reduce back reflections by ensuring that photons propagate in only one direction. 35. The method according to any of the preceding items, further comprising the step of reducing the power level of the input radiation using one or more variable optical attenuators and / or ND filters before the input radiation is supplied to the first splitter. 36. The method according to any of the preceding items, wherein the input radiation has a wavelength between approximately 400 nm and approximately 1600 nm and comprises visible light or infrared light. 37. The method according to any of the preceding items, further comprising the step of calibrating a detector with spectrally matched and equivalent intensity radiation that is output. 38. The method according to any of the preceding items, wherein the detector comprises a multichannel circuit board using one or more photodetectors configured to convert intensity channel optical signals into electrical signals. 39. The method according to any of the preceding items, wherein the detector is associated with semiconductor measurement. 40. The method according to any of the preceding items, further comprising the step of performing lithography, alignment measurements, and / or overlay measurements related to a semiconductor manufacturing process using the spectrally matched and equivalent intensity radiation output. 41. A system configured to emit spectrally matched and equivalent intensity radiation, A radiation source configured to generate radiation, The system comprises an integrating sphere configured to receive radiation from the radiation source and flatten the intensity profile of the radiation, A system having mixed transmission and reflection portions, configured such that one or more outputs from the integrating sphere combine to form spectrally matched and equivalent intensity radiation. 42. The system according to item 41, further comprising a filter configured to filter the infrared (IR) portion of the radiation from the radiation source in order to reduce or eliminate thermal heating of the system. 43. The system according to any of the preceding items, wherein the radiation source comprises a white light source with a wavelength of 500 to 900 nm. 44. The system described in any of the preceding items, wherein one or more outputs have multiple output ports, and each output port has a 200 μm multimode fiber. 45. The system described in any of the preceding items, wherein the plurality of output ports comprises eight output ports. 46. ​​The system described in any of the preceding items, wherein each multimode fiber has a numerical aperture equal to 0.22. 47. The system according to any of the preceding clauses, wherein the radiation source comprises an attenuator configured to be adjusted to achieve different powers at the output port of the multimode fiber. 48. The system according to any of the preceding clauses, wherein the radiation source comprises a spectral filter configured to filter the radiation in order to provide a specific spectrum of the radiation to the integrating sphere. 49. The system according to any of the preceding clauses, wherein the integrating sphere comprises one or more baffles inside it, and the one or more baffles are configured to prevent a path of direct light from the input to the integrating sphere to the one or more outputs. 50. The system according to any of the preceding items, further comprising a photonic crystal fiber configured to propagate the radiation from the radiation source to the integrating sphere. 51. A method for outputting spectrally matched and equivalent intensity radiation, The process of generating radiation using a radiation source, The process includes receiving the radiation from the radiation source using an integrating sphere and flattening it, A method having mixed transmission and reflection portions, wherein one or more outputs from the integrating sphere are configured to combine to form spectrally matched and equivalent intensity radiation. 52. The method according to item 51, further comprising the step of filtering the infrared (IR) portion of the radiation from the radiation source using a filter in order to reduce or eliminate thermal heating of the system. 53. The method according to any of the preceding items, wherein the radiation source comprises a white light source with a wavelength of 500 to 900 nm. 54. The method according to any of the preceding items, wherein the one or more outputs have multiple output ports, and each output port has a 200 μm multimode fiber. 55. The method according to any of the preceding items, wherein the plurality of output ports comprises eight output ports. 56. The method according to any of the preceding items, wherein each multimode fiber has a numerical aperture equal to 0.22. 57. The method according to any of the preceding items, wherein the radiation source comprises an attenuator configured to be adjusted to achieve different powers at the output port of the multimode fiber. 58. The method according to any of the preceding items, wherein the radiation source comprises a spectral filter configured to filter the radiation to provide a specific spectrum of the radiation to the integrating sphere. 59. The method according to any of the preceding items, wherein the integrating sphere comprises one or more baffles inside it, and the one or more baffles are configured to prevent a path of direct light from the input to the integrating sphere to the one or more outputs. 60. The method according to any of the preceding items, further comprising the step of propagating the radiation from the radiation source to the integrating sphere using a photonic crystal fiber.

[0126] The concepts disclosed herein are associated with any common imaging and / or measurement system for imaging sub-wavelength features and are particularly useful for emerging imaging and / or measurement technologies that can generate and / or measure increasingly shorter wavelengths. Emerging technologies already in use include EUV (extreme ultraviolet), DUV lithography which can generate a wavelength of 193 nm using ArF lasers, and DUV lithography which can generate a wavelength of 157 nm using fluorine lasers. Furthermore, EUV lithography can generate wavelengths in the range of 20–5 nm by using a synchrotron or by irradiating material (either solid or plasma) with high-energy electrons to generate photons in this range.

[0127] The concepts disclosed herein can be used for imaging and / or measurement on substrates such as silicon wafers, but it should be understood that the disclosed concepts can be used in any type of lithography imaging and / or measurement system, including those used for imaging and / or measurement on substrates other than silicon wafers. Furthermore, combinations and subcombinations of the disclosed elements may constitute individual embodiments.

[0128] The above description is illustrative, not limiting. Therefore, it will be apparent to those skilled in the art that modifications can be made as described below without departing from the claims.

Claims

1. A system configured to emit spectrally matched and equivalent intensity radiation, A first splitter configured to receive an input radiation and divide it into a first transmitted portion and a first reflected portion, A second splitter configured to receive each of the first transmission portion and reflection portion and further divide them into a second transmission portion and reflection portion, The system comprises one or more combiners configured to combine the second transparent and reflective portions to produce different outputs having mixed transparent and reflective portions, A system in which the aforementioned mixed transmission and reflection portions are configured such that the outputs from the system combine to form spectrally matched and equivalent intensity radiation.

2. The system according to claim 1, further comprising an optical fiber configured to provide an optical path for optically coupling the first splitter, the second splitter, and the one or more combiners.

3. The system according to claim 1, further comprising a spatial optical component configured to provide an optical path for optically coupling the first splitter, the second splitter, and the one or more combiners.

4. The system according to claim 2 or 3, wherein the optical paths have the same optical path length and are spectrally matched.

5. The system according to any one of claims 1 to 4, wherein the different outputs having the mixed transmissive and reflective portions have an equal number of transmissive and reflective portions as a whole.

6. The system according to claim 5, wherein different outputs comprise different mixtures of a transmittance portion and a reflectance portion.

7. The system according to any one of claims 1 to 6, wherein one of the one or more combiners comprises a 2x2 optical coupler.

8. The system according to any one of claims 1 to 7, wherein the first splitter comprises a 1x2 optical splitter.

9. The system according to any one of claims 1 to 8, wherein each of the second splitters comprises a 1x2 optical splitter.

10. The system according to claim 9, wherein the second splitter comprises two 1x2 optical splitters.

11. The system according to claim 9, wherein the second splitter comprises three 1x2 optical splitters.

12. The system according to claim 9, wherein the second splitter comprises 10 1x2 optical splitters.

13. The system according to any one of claims 1 to 12, further comprising a radiation source configured to generate the aforementioned input radiation.

14. The system according to claim 13, further comprising one or more isolators configured to receive the input radiation from the radiation source and reduce back reflections by ensuring that photons propagate in only one direction.

15. The system according to claim 13 or 14, further comprising one or more variable optical attenuators and / or ND filters configured to reduce the power level of the input radiation before the input radiation is provided to the first splitter.

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