Method for on-interest region processing for reticle particle detection

Abstract

An inspection system includes a radiation source that generates a beam of radiation and illuminates a first surface of an object, defining a region of the first surface of the object. The radiation source also illuminates a second surface of the object, defining a region of the second surface, where the second surface is at a different depth level within the object than the first surface. The inspection system can also include a detector that defines a field of view (FOV) of the first surface that includes the region of the first surface and receives radiation scattered from the region of the first surface and the region of the second surface. The inspection system can also include a processor that discards image data that is not received from the region of the first surface and constructs a composite image that includes the image data from throughout the region of the first surface.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Application 62 / 964,924, filed January 23, 2020, and U.S. Application 63 / 036,744, filed June 9, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the detection of contaminants on the photolithographic pattern forming apparatus in photolithography equipment and systems. Background Technology

[0004] A photolithography apparatus is a machine that applies a desired pattern onto a substrate (typically a target portion of the substrate). Photolithography apparatuses can be used, for example, in the fabrication of integrated circuits (ICs) or other devices designed to function. In this context, a patterning apparatus (which may also be called a mask or photomask) can be used to generate a circuit pattern to be formed on a single layer of a device designed to function. This pattern can then be transferred onto target portions (e.g., comprising a portion of a die, one or more dies) on a substrate (e.g., a silicon wafer). Typically, the transfer of the pattern is performed by imaging the pattern onto a layer of radiation-sensitive material (resist) disposed on the substrate. Typically, a single substrate will contain a grid of adjacent target portions patterned sequentially. Known photolithography apparatuses include so-called steppers and so-called scanners. In a stepper, each target portion is irradiated by exposing the entire pattern onto the target portion at once. In a scanner, each target portion is irradiated by scanning the pattern with a radiation beam in a given direction (the “scanning” direction) while simultaneously scanning the substrate parallel to or counter-parallel to this scanning direction. The pattern can also be transferred from the patterning apparatus to the substrate by imprinting the pattern onto the substrate.

[0005] Fabricating devices (such as semiconductor devices) typically involves processing a substrate (e.g., a semiconductor wafer) using multiple fabrication processes to form various features and typically multiple layers of the device. These layers and / or features are typically fabricated and / or processed using processes such as deposition, photolithography, etching, chemical mechanical polishing, and ion implantation. Multiple devices can be fabricated on multiple dies on a substrate and then separated into multiple individual devices. This device fabrication process can be considered a patterning process. A patterning process involves a patterning transfer step, such as optical and / or nanoimprint lithography using a photolithography apparatus, to provide a pattern on the substrate, and typically, but optionally, involves one or more associated patterning processing steps, such as resist development by a developing apparatus, baking the substrate using a baking tool, etching the pattern by an etching apparatus, etc. Additionally, one or more metrology processes are included in the patterning process.

[0006] Measurement procedures are used at various steps during the patterning process to monitor and / or control the process. For example, measurement procedures are used to measure one or more properties of the substrate, such as the relative location (e.g., registration, overlap, alignment, etc.) or dimensions (e.g., linewidth, critical dimension (CD), thickness, etc.) of features formed on the substrate during the patterning process, such that the performance of the patterning process can be determined, for example, based on the one or more properties. If the one or more properties are unacceptable (e.g., outside a predetermined range), one or more variables of the patterning process can be designed or modified, for example, based on the measurements of the one or more properties, so that the substrate manufactured by the patterning process has acceptable properties.

[0007] With advancements in photolithography and other patterning techniques, the size of functional elements has continued to shrink, while the number of functional elements (such as transistors) per device has steadily increased over the past few decades. Simultaneously, the requirements for accuracy, precision, in areas such as overlap and critical dimensions, have become increasingly stringent. Errors (such as overlap errors, CD errors, etc.) will inevitably arise during the patterning process. For example, imaging errors may occur due to optical aberrations, heating of the patterning apparatus, errors in the patterning apparatus, and / or substrate heating, and can be characterized by, for example, overlap, CD, etc. Alternatively, these errors may be introduced in other parts of the patterning process (such as etching, developing, baking, etc.), and similarly can be characterized by, for example, overlap, CD, etc. These errors may cause problems with the functional operation of the device, including device malfunction, contamination, or one or more electrical problems with the functional device. Thus, these errors may also contribute to increased costs due to inefficient processing, waste, and processing delays.

[0008] One such error that may arise is contaminants on the surface of the photolithographic patterning apparatus. Such contaminants may include particles present on the surface of the photolithographic patterning apparatus that may affect the etching itself and / or subsequent or subsequent inaccuracies in the patterning process, which may lead to damaged and / or malfunctioning circuitry.

[0009] Another error can be due to false positive detections of particles. During the inspection operation, the detector may receive light reflected away from the pattern. This reflection produces false positive detections that indicate the possible presence of particles. Furthermore, such signals may interfere with other optical signals received from particles at the rear of the photolithographic pattern forming apparatus. Therefore, such interference can lead to false positive detections, where the system might determine that a particle is present where it is not. Summary of the Invention

[0010] Therefore, it is desirable to be able to characterize one or more of these errors and take measures to design, modify, control, etc., the patterning process to reduce or minimize one or more of these errors. Furthermore, it is necessary to determine the level / degree of contamination in the patterning apparatus, including the size and location of the contaminants, and to determine whether the device is accepted because it is within a predetermined tolerance or rejected because it is contaminated beyond the predetermined tolerance.

[0011] In some embodiments, inspection systems and methods for minimizing false alarm detection in photolithography inspection systems are described. According to some embodiments, an inspection system is disclosed including a radiation source that generates a radiation beam. In some aspects, the radiation source irradiates a first surface of an object, a first parameter of the beam defining a region of the first surface of the object. Additionally, the radiation source also irradiates a second surface of the object, a second parameter of the beam defining a region of the second surface, wherein the second surface is located within the object at a different depth level than the first surface. The inspection system also includes a detector that defines a field of view (FOV) of the first surface including the region of the first surface and receives radiation scattered from the region of the first surface and the region of the second surface. According to some aspects, the inspection system may also include a processing circuitry system that discards image data not received from the region of the first surface and constructs a composite image, the composite image including the image data from the entire region covering the first surface.

[0012] In some embodiments, the system includes an illumination system, an aperture stop, an optical system, and a detector. The illumination system is configured to transmit an illumination beam along an illumination path. The aperture stop is configured to select a portion of the illumination beam. The optical system is configured to transmit the selected portion of the illumination beam toward a mask and transmit a signal beam scattered from the mask. The detector is configured to detect the signal beam. The illumination system, the aperture stop, the optical system, and the detector are optically coaxial.

[0013] In some embodiments, the aperture stop includes an apodization aperture stop. In some embodiments, the apodization aperture stop includes a quarter-disc aperture stop or a crescent-shaped aperture stop. In some embodiments, in bright-field mode, the aperture stop includes an apodization quarter-disc aperture stop configured to transmit the central portion of the illumination beam and provide an angle-insensitive off-axis illumination beam toward the mask. In some embodiments, in dark-field mode, the aperture stop includes an apodization crescent-shaped aperture stop configured to block the central portion of the illumination beam and provide an angle-sensitive off-axis illumination beam toward the mask. In some embodiments, the numerical aperture of the focusing lens of the optical system is larger than the numerical aperture of the converging lens of the optical system to increase the intensity of the signal beam.

[0014] In some embodiments, the aperture stop includes an electro-optical aperture stop module configured to control the transmission of the illumination beam through the aperture stop. In some embodiments, the electro-optical aperture stop module controls the transmission of the illumination beam in three degrees of freedom. In some embodiments, these three degrees of freedom include radial range, angular range, and intensity.

[0015] In some embodiments, the aperture stop includes an optomechanical aperture stop module configured to control the transmission of the illumination beam through the aperture stop. In some embodiments, the optomechanical aperture stop module includes a plurality of aperture stop masks.

[0016] In some embodiments, the illumination system includes an electro-optical illumination module configured to electronically control the illumination beam. In some embodiments, the electro-optical illumination module includes a digital micromirror device (DMD), a liquid crystal modulator (LCM), a spatial light modulator (SLM), and / or combinations thereof. In some embodiments, the electro-optical illumination module controls the numerical aperture of the illumination beam.

[0017] In some embodiments, a first adjustment to the numerical aperture of the illumination beam and a second adjustment to the aperture stop provide multiple illumination angles for the mask. In some embodiments, the system further includes a controller coupled to the illumination system, the aperture stop, and / or the detector. In some embodiments, the controller is configured to provide real-time feedback for image acquisition of the signal beam.

[0018] In some embodiments, the optical system includes a linear polarizer, a polarization beam splitter, and a quarter-wave plate. In some embodiments, the optical system is configured to block stray radiation from the signal beam. In some embodiments, the optical system includes a focusing lens, a beam splitter, and a converging lens. In some embodiments, the numerical aperture of the focusing lens is larger than the numerical aperture of the converging lens to increase the intensity of the signal beam.

[0019] In some embodiments, the illumination beam includes a structured light pattern. In some embodiments, the illumination beam includes multiple narrow spectral bands.

[0020] In some embodiments, the system includes an illumination system, an aperture stop, an optical system, and a detector. The illumination system is configured to transmit an illumination beam along an illumination path, and the illumination beam includes a structured light pattern. The aperture stop is configured to select a portion of the illumination beam, and the aperture stop includes an apodization aperture stop. The optical system is configured to transmit the selected portion of the illumination beam toward a target and transmit a signal beam scattered from the target. The detector is configured to detect the signal beam.

[0021] In some embodiments, the structured light pattern includes amplitude modulation (AM). In some embodiments, the AM includes a spatial frequency of less than 50 cycles / mm. In some embodiments, the AM includes three patterns configured to identify the virtual light contribution of the target based on image characteristics of each region of interest, including particle signal, particle depth, and / or the target.

[0022] In some embodiments, the structured light pattern includes frequency modulation (FM). In some embodiments, the FM includes a spatial frequency of less than 50 cycles / mm. In some embodiments, the FM includes three patterns configured to identify the virtual light contribution of the target based on the Fourier transform characteristics of each region of interest, including particle signal, particle depth, and / or the virtual light contribution of the target.

[0023] In some embodiments, the illumination system, the aperture stop, the optical system, and the detector are aligned along the optical axis.

[0024] In some embodiments, the apparatus includes an illumination system, a projection system, and an inspection system. The illumination system is configured to illuminate a pattern forming apparatus. The projection system is configured to project an image of the pattern forming apparatus onto a substrate. The inspection system is configured to detect particles on the pattern forming apparatus. The inspection system includes a second illumination system, an aperture stop, an optical system, and a detector. The second illumination system is configured to transmit an illumination beam along an illumination path. The aperture stop is configured to select a portion of the illumination beam. The optical system is configured to transmit the selected portion of the illumination beam toward the pattern forming apparatus and transmit a signal beam scattered from the pattern forming apparatus. The detector is configured to detect the signal beam. The second illumination system, the illumination system, the aperture stop, the optical system, and the detector are aligned along an optical axis.

[0025] In some embodiments, in bright-field mode, the aperture stop includes an apodized quarter-disc aperture stop configured to transmit a central portion of the illumination beam and provide an angle-insensitive off-axis illumination beam toward the pattern forming apparatus. In some embodiments, in dark-field mode, the aperture stop includes an apodized crescent-shaped aperture stop configured to block a central portion of the illumination beam and provide an angle-sensitive off-axis illumination beam toward the pattern forming apparatus. In some embodiments, the apparatus further includes a second inspection system arranged opposite to the inspection system. In some embodiments, the apparatus further includes a second inspection system arranged adjacent to the inspection system.

[0026] Further features and advantages of this disclosure, as well as the structure and operation of various embodiments of this disclosure, are described in detail below with reference to the accompanying drawings. It should be noted that this disclosure is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Further embodiments will be apparent to those skilled in the art based on the teachings contained herein. Attached Figure Description

[0027] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and enable those skilled in the art to make and use the present disclosure.

[0028] Figure 1A A schematic diagram of a reflective lithography apparatus according to an exemplary embodiment is shown.

[0029] Figure 1B A schematic diagram of a transmission lithography apparatus according to an exemplary embodiment is shown.

[0030] Figure 2 A detailed schematic diagram of a reflective lithography apparatus according to an exemplary embodiment is shown.

[0031] Figure 3 A schematic diagram of a photolithography unit according to an exemplary embodiment is shown.

[0032] Figure 4 A schematic diagram of a measurement system according to an exemplary embodiment is shown.

[0033] Figure 5 This illustrates signal interference occurring at the detector, according to an exemplary embodiment, between the signal reflected from the particle and the signal reflected from the diffraction pattern.

[0034] Figure 6 This is an illustration of an illumination method for the region of interest at a certain moment or during each illumination, according to an exemplary embodiment.

[0035] Figure 7 The figure illustrates the sequence of operations for reconstructing a synthetic image based on subsequently acquired images of the region of interest, according to an exemplary embodiment.

[0036] Figure 8 The figure illustrates a schematic diagram of a data acquisition and preprocessing pipeline according to an exemplary embodiment.

[0037] Figures 9A to 9C The figure shows a schematic cross-section of an illustration of an illumination and observation system according to an exemplary embodiment in the region of interest.

[0038] Figure 10 The figure illustrates an example shape of the region of interest for irradiating a non-uniform surface of a film, according to an exemplary embodiment.

[0039] Figure 11A The figure illustrates an optical-mechanical schematic diagram of a system capable of achieving high-resolution imaging of the entire photolithographic pattern forming apparatus using multiple regions of interest, according to an exemplary embodiment.

[0040] Figure 11B The figure illustrates a flowchart of an inspection method according to an exemplary embodiment.

[0041] Figure 12 The figure shows an optical-mechanical schematic diagram of a particle detection system according to an exemplary embodiment.

[0042] Figure 13 The figure illustrates a grid covering the entire surface of a photolithographic pattern forming apparatus according to an exemplary embodiment.

[0043] Figure 14 The figure illustrates radiation operations in different regions within the illuminated camera field of view according to an exemplary embodiment.

[0044] Figure 15 The figure shows a schematic diagram of the optical and mechanical setup of a measurement system according to an exemplary embodiment.

[0045] Figure 16 The figure illustrates an example sequence of Gray code patterns, i.e., grey code patterns, according to an exemplary embodiment, which are projected to calibrate the horizontal and vertical coordinates of an observation illumination system.

[0046] Figure 17 The figure illustrates the temporal intensity distribution obtained in pixels according to an exemplary embodiment.

[0047] Figure 18 The figure illustrates the system configuration of an observation-irradiation system according to an exemplary embodiment.

[0048] Figure 19 The figure illustrates an exemplary embodiment. Figure 18 The spectral bands of the observation and illumination system.

[0049] Figure 20 The figure illustrates the configuration of an irradiation-detection system according to an exemplary embodiment.

[0050] Figure 21 The figure illustrates the configuration of an irradiation-detection system according to an exemplary embodiment.

[0051] Figure 22 The figure illustrates the configuration of an irradiation-detection system according to an exemplary embodiment.

[0052] Figure 23 The figure illustrates an example emission spectrum of a light source incorporated into an illumination system according to an exemplary embodiment.

[0053] Figure 24 The figure illustrates the diffraction properties of a patterned portion of a photolithographic pattern forming apparatus according to an exemplary embodiment, wherein electromagnetic radiation incident on the photolithographic pattern forming apparatus can be redirected to a detection system.

[0054] Figure 25 The figure illustrates intensity amplitude data between detected polarized and unpolarized reflections according to an exemplary embodiment.

[0055] Figure 26 This is a schematic cross-sectional view of a coaxial inspection system according to an exemplary embodiment.

[0056] Figure 27 This is according to an exemplary embodiment. Figure 26 A schematic perspective view of the coaxial inspection system shown in the figure.

[0057] Figure 28 This is according to an exemplary embodiment. Figure 27The graph shows the modulation transfer function (MTF) distribution of the coaxial inspection system.

[0058] Figure 29 This is according to an exemplary embodiment. Figure 26 A schematic perspective view of the coaxial inspection system shown in the figure.

[0059] Figure 30 This is according to an exemplary embodiment. Figure 29 The graph shows the MTF distribution of the coaxial inspection system.

[0060] Figure 31 This is a schematic cross-sectional view of an alternative coaxial inspection system with a polarization optics system according to an exemplary embodiment.

[0061] Figure 32 This is a schematic cross-sectional view of a region of interest (ROI) inspection system according to an exemplary embodiment.

[0062] Figures 33A to 33C This is according to an exemplary embodiment. Figure 32 The diagram shows a schematic perspective view of the ROI inspection system and image acquisition for each ROI.

[0063] Figure 34 This is a schematic cross-sectional view of an AM inspection system according to an exemplary embodiment.

[0064] Figure 35 This is a schematic cross-sectional view of an FM inspection system according to an exemplary embodiment.

[0065] Figure 36 This is a schematic cross-sectional view of an inspection array system according to an exemplary embodiment.

[0066] The features and advantages of this disclosure will become more apparent from the following detailed description, when taken in conjunction with the accompanying drawings, in which the same reference numerals identify corresponding elements throughout the document. In the drawings, the same reference numerals generally indicate the same, functionally similar, and / or structurally similar elements. Additionally, generally, the leftmost numeral of the reference numerals identifies the drawing in which said reference numeral first appears. Unless otherwise indicated, the drawings provided throughout this disclosure should not be construed as tolerancing drawings. Detailed Implementation

[0067] This specification discloses one or more embodiments incorporating features of this disclosure. The disclosed embodiments are merely illustrative of this disclosure. The scope of this disclosure is not limited to the disclosed embodiments. This disclosure is defined by the appended claims.

[0068] The described embodiments and the references to "an embodiment," "embodiment," "exemplary embodiment," etc., used in the specification indicate that the described embodiments may include specific features, structures, or characteristics, but each embodiment may not necessarily include the specific features, structures, or characteristics stated herein. Furthermore, such phrases do not necessarily refer to the same embodiment. Additionally, when a specific feature, structure, or characteristic is described in connection with an embodiment, it should be understood that, whether explicitly described or not, implementing such a feature, structure, or characteristic in combination with other embodiments is within the knowledge of those skilled in the art.

[0069] For ease of description, spatial relative terms such as “below,” “under,” “lower,” “above,” “on,” “higher,” etc., are used herein to readily describe the relationship between one element or feature and another, as illustrated in the accompanying drawings. These spatial relative terms are intended to cover different orientations of the device other than those depicted in the figures during use or operation. The device may be otherwise oriented (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein may be interpreted accordingly.

[0070] As used herein, the term "approximately" indicates the value of a given quantity that may vary based on a particular technique. Based on the particular technique, the term "approximately" may indicate the value of a given quantity that varies, for example, within 10% to 30% above or below the value (e.g., ±10%, ±20%, or ±30% of the value).

[0071] Embodiments of this disclosure may be implemented using hardware, firmware, software, or any combination thereof. Embodiments of this disclosure may also be implemented as instructions stored on a machine-readable medium that can be read and executed by one or more processors. A machine-readable medium may include any means for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM); random access memory (RAM); disk storage media; optical storage media; flash storage devices; electrical, optical, acoustic, or other forms of propagation signals (e.g., carrier waves, infrared signals, digital signals, etc.). Additionally, in this document, firmware, software, routines, and / or instructions may be described as performing certain actions. However, it should be understood that such descriptions are merely for convenience, and these actions are actually produced by a computing device, processor, controller, or other means of executing firmware, software, routines, non-transitory computer-readable instructions, etc.

[0072] However, it is helpful to present example environments in which embodiments of this disclosure may be implemented before describing such embodiments in more detail.

[0073] Exemplary lithography system

[0074] Figure 1A and Figure 1B These are schematic diagrams of lithography apparatus 100 and lithography apparatus 100' according to some embodiments. In some embodiments, lithography apparatus 100 and lithography apparatus 100' each include the following components: an irradiation system (irradiator) IL configured to modulate a radiation beam B (e.g., deep ultraviolet or extreme ultraviolet (EUV) radiation); a support structure (e.g., a mask stage) MT configured to support a patterning apparatus (e.g., a mask, a stencil, or a dynamic patterning apparatus) MA and connected to a first positioner PM configured to accurately position the patterning apparatus MA; and a substrate stage (e.g., a wafer stage) WT configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioner PW configured to accurately position the substrate W. Other configurations of the irradiator may be implemented to improve irradiation and design compactness, as will be further described herein.

[0075] Lithography apparatuses 100 and 100' also have a projection system PS configured to project a pattern, imparted by a radiation beam B by a patterning apparatus MA, onto a target portion (e.g., comprising one or more dies) C of a substrate W. In lithography apparatus 100, the patterning apparatus MA and the projection system PS are reflective. In lithography apparatus 100', the patterning apparatus MA and the projection system PS are transmissive.

[0076] The irradiation system IL may include various types of optical components, such as refractive, reflective, reflective-refractive, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for guiding, shaping, or controlling the radiation beam B.

[0077] The support structure MT holds the patterning apparatus MA in a manner that depends on the orientation of the patterning apparatus MA relative to a reference frame, the design of at least one of the lithography apparatuses 100 and 100', and other conditions such as whether the patterning apparatus MA is held in a vacuum environment. The support structure MT can hold the patterning apparatus MA using mechanical, vacuum, electrostatic, or other clamping techniques. The support structure MT can be a frame or a stage, and for example, it can be fixed or movable as needed. By using sensors, the support structure MT can ensure that the patterning apparatus MA is positioned, for example, relative to the projection system PS.

[0078] The term "patterning apparatus" MA should be interpreted broadly as any apparatus capable of imparting a pattern to the radiation beam B in the cross-section of the radiation beam B to generate a pattern in a target portion C of the substrate W. The pattern imparted to the radiation beam B may correspond to a specific functional layer of a device created in the target portion C to form an integrated circuit.

[0079] The pattern forming apparatus MA can be a transmissive type (such as in...). Figure 1B (as in a lithography device 100') or reflective (as in...) Figure 1A (As in the photolithography apparatus 100). Examples of pattern forming apparatus MA include a mask, a mask, a programmable mirror array, and a programmable LCD panel. Masks are well known in photolithography and include mask types such as binary mask types, alternating phase-shift mask types, attenuation phase-shift mask types, and various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect the incident radiation beam in different directions. The tilted mirrors impart a pattern to the radiation beam B reflected by the matrix of small mirrors.

[0080] As used herein, the term "projection system" PS can encompass any type of projection system, including refractive, reflective, reflective-refractive, magnetic, electromagnetic, and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation used, or for other factors such as the use of an immersion liquid on a substrate W or the use of a vacuum. A vacuum environment can be used for EUV or electron beam radiation because other gases may absorb excessive radiation or electrons. A vacuum environment may therefore be provided throughout the beam path by means of vacuum walls and a vacuum pump.

[0081] The lithography apparatus 100 and / or lithography apparatus 100' can be of the type having two (dual-platform) or more substrate stages WT (and / or two or more mask stages). In such a "multi-platform" machine, additional substrate stages WT can be used in parallel, or one or more other substrate stages WT can be used for exposure while preparatory steps are performed on one or more stages. In some cases, the additional stage may not be a substrate stage WT.

[0082] refer to Figure 1A and Figure 1B The irradiator IL receives a radiation beam from the radiation source SO. When the source SO is an excimer laser, the source SO and the lithography apparatus 100, 100' can be separate physical entities. In this case, the source SO is not considered to be part of the lithography apparatus 100 or 100', and the radiation beam is delivered by means of a beam delivery system BD (in which, for example, a suitable directional mirror and / or beam expander) Figure 1B(In the middle) the beam is transferred from the source SO to the irradiator IL. In other cases, the source SO may be a component of the lithography apparatus 100, 100' – for example, when the source SO is a mercury lamp. The source SO, the irradiator IL, and the beam transfer system BD, which may be provided if necessary, can be collectively referred to as the radiation system.

[0083] The irradiator IL may include an adjuster AD for adjusting the angular intensity distribution of the radiation beam (in... Figure 1B (In the middle). Typically, at least the outer radial range and / or inner radial range (often referred to as "σ-outer" and "σ-inner", respectively) of the intensity distribution in the pupil plane of the irradiator can be adjusted. Furthermore, the irradiator IL may include various other components (in... Figure 1B (In the middle), such as integrator IN and concentrator CO. Irradiator IL can be used to adjust the radiation beam B to have the desired uniformity and intensity distribution in its cross-section.

[0084] refer to Figure 1A The radiation beam B is incident on and patterned by the patterning apparatus (e.g., a mask) MA, which is held on the support structure (e.g., a mask stage) MT. In the lithography apparatus 100, the radiation beam B is reflected from the patterning apparatus (e.g., the mask) MA. After being reflected from the patterning apparatus (e.g., the mask) MA, the radiation beam B is passed through the projection system PS, which focuses the radiation beam B onto the target portion C of the substrate W. The substrate stage WT can be accurately moved (e.g., to position different target portions C in the path of the radiation beam B) by means of a second positioner PW and a position sensor IF2 (e.g., an interferometer device, a linear encoder, or a capacitive sensor). Similarly, the first positioner PM and another position sensor IF1 can be used to accurately position the patterning apparatus (e.g., the mask) MA relative to the path of the radiation beam B. The pattern forming apparatus (e.g., mask) MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2.

[0085] refer to Figure 1BThe radiation beam B is incident on and patterned by the patterning apparatus (e.g., a mask MA), which is held on the support structure (e.g., a mask stage MT). Having passed through the mask MA, the radiation beam B is transmitted through the projection system PS, which focuses the beam onto the target portion C of the substrate W. The projection system has a pupil PPU conjugate to the illumination system pupil IPU. The radiated portion originates from the intensity distribution at the illumination system pupil IPU and passes through the mask pattern unaffected by diffraction at the mask pattern, producing an image of the intensity distribution at the illumination system pupil IPU.

[0086] With the aid of a second positioner PW and a position sensor IF (e.g., an interferometer device, a linear encoder, or a capacitive sensor), the substrate stage WT can be moved precisely (e.g., to position different target portions C in the path of the radiation beam B). Similarly, (e.g., after mechanical acquisition from a mask library or during scanning) the first positioner PM and another position sensor (not in use) can be moved. Figure 1B (As shown in the figure) is used to accurately position the mask MA relative to the path of the radiation beam B.

[0087] In some embodiments, the movement of the mask stage MT can be achieved by means of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning) forming part of the first positioner PM. Similarly, the movement of the substrate stage WT can be achieved by using a long-stroke module and a short-stroke module forming part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask stage MT may be connected only to the short-stroke actuator, or it may be fixed. The mask MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the substrate alignment marks (as illustrated) occupy dedicated target portions, they can be located in the space between multiple target portions (referred to as scribing alignment marks). Similarly, when more than one die is disposed on the mask MA, the mask alignment marks can be located between these dies.

[0088] The mask stage MT and patterning apparatus MA can be located within a vacuum chamber, where an in-vacuum robot IVR can be used to move the patterning apparatus (such as a mask) into and out of the vacuum chamber. Alternatively, when the mask stage MT and patterning apparatus MA are outside the vacuum chamber, an out-of-vacuum robot can be used for various transport operations similar to the in-vacuum robot IVR. Both the in-vacuum and out-of-vacuum robots need to be calibrated to smoothly transfer any payload (e.g., a mask) onto a fixed kinematic support at the transfer station.

[0089] The lithography apparatus 100' may include a patterning apparatus transfer system. An example patterning apparatus transfer system may be a patterning apparatus exchange device (V), including, for example, an in-vacuum robot (IVR), a mask stage (MT), a first positioner (PM), and other similar components for transferring and positioning the patterning apparatus. The patterning apparatus exchange device V may be configured to transfer the patterning apparatus, which carries a container, between a processing tool (e.g., the lithography apparatus 100').

[0090] The photolithography equipment 100 and 100' can be used in at least one of the following modes:

[0091] 1. In step mode, while keeping the support structure (e.g., mask stage) MT and the substrate stage WT substantially stationary, the entire pattern imparted to the radiation beam B is projected onto the target portion C in one pass (i.e., single static exposure). The substrate stage WT is then moved along the X and / or Y directions, allowing exposure of different target portions C.

[0092] 2. In scanning mode, while simultaneously scanning the support structure (e.g., mask stage) MT and the substrate stage WT, the entire pattern of the radiation beam B is projected onto the target portion C in a single exposure (i.e., a single dynamic exposure). The velocity and orientation of the substrate stage WT relative to the support structure (e.g., mask stage) MT can be determined by the magnification (reduction) and image inversion characteristics of the projection system PS.

[0093] 3. In another mode, while the support structure (e.g., mask stage) MT of the programmable patterning apparatus is kept substantially fixed and the substrate stage WT is moved or scanned, a pattern imparted to the radiation beam B is projected onto the target portion C. A pulsed radiation source SO can be used, and the programmable patterning apparatus can be updated as needed after each movement of the substrate stage WT or between consecutive radiation pulses during scanning. This mode of operation can be readily applied to maskless lithography employing programmable patterning apparatuses such as programmable mirror arrays.

[0094] Alternatively, combinations and / or variations of the usage patterns described above, or entirely different usage patterns, can be used.

[0095] In some embodiments, the lithography apparatus 100 includes an extreme ultraviolet (EUV) source configured to generate an EUV radiation beam for EUV lithography. Typically, the EUV source is configured in a radiation system, and a corresponding irradiation system is configured to modulate the EUV radiation beam from the EUV source.

[0096] Figure 2The lithography apparatus 100 is shown in more detail, including the source collector device SO, the irradiation system IL, and the projection system PS. The source collector device SO is constructed and arranged such that a vacuum environment can be maintained within the enclosure structure 220 of the source collector device SO. The plasma 210 emitting EUV radiation can be formed by a discharge-generated plasma source. EUV radiation can be generated by a gas or vapor, such as xenon, lithium vapor, or tin vapor, wherein a very hot plasma 210 is generated to emit radiation in the EUV range of the electromagnetic spectrum. For example, the very hot plasma 210 is generated by a discharge that causes at least partial ionization of the plasma. For efficient radiation generation, Xe, Li, Sn vapor, or any other suitable gas or vapor with a partial pressure of 10 Pa may be required. In some embodiments, an excited tin (Sn) plasma is provided to generate EUV radiation.

[0097] Radiation emitted by thermal plasma 210 is transferred from source chamber 211 to collector chamber 212 via an optional gas barrier or contaminant trap 230, i.e., a contaminant trap (in some cases, also referred to as a contaminant barrier or foil trap), positioned in or behind an opening in source chamber 211. The contaminant trap 230 may include a channel structure. The contaminant trap 230 may also include a gas barrier, or a combination of a gas barrier and a channel structure. As is known in the art, the contaminant trap 230 or contaminant barrier further indicated herein includes at least a channel structure.

[0098] Source chamber 211 may include a radiation collector CO, which may be a so-called grazing incidence collector. The radiation collector CO has an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation passing through the collector CO may be reflected off a grating spectral filter 240 to be focused at a virtual source point IF. This virtual source point IF is often referred to as an intermediate focus, and the source collector device is arranged such that the intermediate focus IF is located at or near an opening 219 in the enclosure structure 220. The virtual source point IF is an image of the plasma 210 emitting radiation. The grating spectral filter 240 is specifically used to suppress infrared (IR) radiation.

[0099] Subsequently, radiation traverses an illumination system IL, which may include a faceted field mirror assembly 222 and a faceted pupil mirror assembly 224. The faceted field mirror assembly 222 and the faceted pupil mirror assembly 224 are arranged to provide a desired angular distribution of the radiation beam 221 at the patterning apparatus MA, and desired uniformity of radiation intensity at the patterning apparatus MA. As the radiation beam 221 is reflected at the patterning apparatus MA, held by the support structure MT, a patterned beam 226 is formed, and the patterned beam 226 is imaged by the projection system PS via reflective elements 228 and 229 onto a substrate W held by a wafer platform or substrate stage WT.

[0100] The irradiation optical unit IL and projection system PS can typically contain more elements than are shown. The grating spectral filter 240 may be optional, depending on the type of lithography apparatus. Additionally, more mirrors than are shown in the figure, for example, in the projection system PS, there may be additional mirrors besides those shown. Figure 2 In addition to the reflective element shown, there are 1 to 6 additional reflective elements.

[0101] Collector optics CO (e.g.) Figure 2 The image shown is depicted as a nested collector with grazing incidence reflectors 253, 254, and 255, and is only an example of a collector (or collector mirror). The grazing incidence reflectors 253, 254, and 255 are arranged symmetrically about the optical axis O, and this type of collector optics CO is preferably used in conjunction with a plasma source generated by discharge (often referred to as a DPP source).

[0102] Exemplary photolithography unit

[0103] Figure 3A schematic diagram of a lithography unit 300, sometimes also referred to as a lithography cell or lithography cluster, is shown. A lithography apparatus 100 or 100' may form part of the lithography unit 300. The lithography unit 300 may also include equipment for performing pre-exposure and post-exposure processes on a substrate. Conventionally, this equipment includes: a spin coater SC for depositing a resist layer, a developer DE for developing the exposed resist, a chill plate CH, and a baking plate BK. A substrate transport device, or robot RO, picks up substrates from input port I / O1 and output port I / O2, moves the substrates between different process devices, and transports them to the feed stage LB of the lithography apparatus. These devices are generally collectively referred to as a track or coating and developing system and are controlled by a track control unit or coating and developing system control unit TCU, which is itself controlled by a management control system SCS, which also controls the lithography apparatus via a lithography control unit LACU. Thus, different devices can be operated to maximize throughput and processing efficiency.

[0104] Exemplary Measurement System

[0105] Figure 4 A schematic diagram of a measurement system 400, which may be implemented as part of a lithography apparatus 100 or 100' according to some embodiments, is shown. In some embodiments, the measurement system 400 may be configured to measure the height and height variation on the surface of a substrate W. In some embodiments, the measurement system 400 may be configured to detect the position of alignment marks on the substrate and use the detected position of the alignment marks to align the substrate relative to patterning apparatus or other components of the lithography apparatus 100'.

[0106] In some embodiments, the measurement system 400 may include a radiation source 402, a projection grating 404, a detection grating 412, and a detector 414. The radiation source 402 may be configured to provide a narrow-band electromagnetic radiation beam having one or more passbands. In some examples, the one or more passbands may be within a spectrum with wavelengths between about 500 nm and about 900 nm. In another example, the one or more passbands may be discrete narrow passbands within a spectrum with wavelengths between about 500 nm and about 900 nm. In yet another example, the radiation source 402 produces light within the ultraviolet (UV) spectrum with wavelengths between about 225 nm and 400 nm. The radiation source 402 may also be configured to provide one or more passbands with a substantially constant center wavelength (CWL) value over a long period of time (e.g., over the lifetime of the radiation source 402). As discussed above, in current measurement systems, this configuration of the radiation source 402 can help prevent the actual CWL value from shifting from the desired CWL value. Furthermore, as a result, the use of a constant CWL value can improve the long-term stability and accuracy of the measurement system (e.g., measurement system 400) compared to the current measurement system.

[0107] The projection grating 404 may be configured to receive one or more beams generated from the radiation source 402 and to provide a projected image onto the surface of the substrate 408. An imaging optics device 406 may be included between the projection grating 404 and the substrate 408, and may include one or more lenses, mirrors, gratings, etc. In some embodiments, the imaging optics device 406 is configured to focus the image projected from the projection grating 404 onto the surface of the substrate 408.

[0108] In some embodiments, the projection grating 404 is imaged onto the surface of the substrate 408 at an angle θ relative to the surface normal. The image is reflected from the substrate surface and re-imaged on the detection grating 412. The detection grating 412 may be the same as the projection grating 404. An imaging optics 410 may be included between the substrate 408 and the substrate detection grating 412, and may include one or more lenses, mirrors, gratings, etc. In some embodiments, the imaging optics 410 is configured to focus the image reflected from the surface of the substrate 408 onto the detection grating 412. Due to the oblique incidence, when the image projected by the projection grating 404 is received by the detection grating 412, a height change (Zw) in the surface of the substrate 408 will cause the image to be shifted by a distance (s), which is given by the following equation (1):

[0109] (1)

[0110] In some embodiments, a shifted image of a projection grating 404 is partially transmitted by a detection grating 412, and the transmission intensity is a periodic function of the image shift. This shifted image is received and measured by a detector 414. The detector 414 may include a photodiode or an array of photodiodes. Other examples of the detector 414 include a CCD array. In some embodiments, the detector 414 may be designed to measure wafer height variations as low as 1 nm based on the received image. In some aspects, the system can operate without the detection grating 412. In other aspects, the detection grating 412 and the projection grating 404 may have spatial frequencies spanning from 0 to infinity (0 spatial frequency = cover plate).

[0111] Exemplary embodiments of particle inspection systems

[0112] Figure 5 This illustration shows the signal interference between the signal reflected from the particle and the signal reflected from the diffraction pattern at the detector, according to some embodiments. Photolithography inspection systems are used to locate and determine the size of particles located on a photolithography patterning apparatus. Due to the optical properties of the photolithography patterning apparatus, the coating, and the pattern of the photolithography patterning apparatus, combined with requirements for quality, repeatability, and detection probability, particle detection systems need to meet stringent technical requirements. Among those requirements, two key parameters to be addressed are the accuracy and precision of particle size measurement, and the achievement of a low false alarm detection rate. Several approaches have been considered in the industry to improve the accuracy and precision of particle size measurement; however, such approaches (e.g., parallax-based optical systems and intensity-based image analysis systems) may not provide sufficient attenuation of the false alarm rate.

[0113] In some aspects, there may be little control over how the irradiation system can control how the irradiation light penetrates the photolithography patterning apparatus and the film-patterning chamber. For example, as Figure 5As illustrated, the photolithographic pattern forming apparatus or mask 502 receives flood illumination 504 for inspection purposes, to check for the presence of particles 506 on the surface of the photolithographic pattern forming apparatus. Light entering the photolithographic pattern forming apparatus or mask 502 also reaches the diffraction pattern 508 on the front side of the photolithographic pattern forming apparatus and is reflected back through the imaging system receiving cone region 510 and enters the imaging system 512. Therefore, the detector 514 within the imaging system 512 can receive an image of the particles 506 (indicating contaminants) and / or an image 516 generated by the diffraction pattern 508. In some systems, the large angle between the illumination optical axis and the observation optical axis makes it highly possible that the illumination beam illuminating the diffraction pattern, and the light diffracted from the diffraction pattern after reflection from the back surface of the photolithography, is ultimately redirected into the imaging system 512 and detected as having contaminants (false alarm). Given the nature and spatial constraints of the inspection system, a fixed illumination scheme can be used, and the system can operate within a certain wavelength range where the surface under investigation for particle presence is opaque or has a transmittance low enough to attenuate the diffraction pattern signal to the background level, thereby minimizing the probability of false alarms. Therefore, in one aspect, Figure 5 The diagram illustrates particles 506 that can be located on the glass side of mask 502, and diffraction structures (patterns) 508 that can be located on the front side of mask 502.

[0114] In some embodiments, data collection and analysis can reduce the probability of false alarm detection. Therefore, as will be further described herein, embodiments of this disclosure resolve / can eliminate interference caused by unwanted illumination of the diffraction pattern and subsequent reflections of the pattern received at the imaging system. Some embodiments include: illuminating multiple regions of interest (ROIs) within a photolithographic patterning apparatus, processing ROI images for only one side of the photolithographic patterning apparatus, and stitching the multiple ROI images into a single composite image.

[0115] Figure 6The figure illustrates an illumination method according to some embodiments, illuminating a region of interest at a specific time or each time. In this example, a flexible spatiotemporal illumination system is used, enabling selective illumination of any region (e.g., ROI) within the field of view (FOV) of the detection system. Such an illumination system can be constructed using, for example, an optical system with an intermediate image plane. To spatially alternate the amplitude of light in the image plane, a light modulation element can be placed in the intermediate image plane. Examples of feasible light modulation elements for achieving this include liquid crystal display (LCD) modules, digital micromirror device (DMD) modules, patterned glass plates, movable apertures or aperture gates, etc. Therefore, the light modulation element can be externally controlled or a statically interchangeable element utilizing the absorption and / or reflection properties of passive / active components.

[0116] exist Figure 6 The diagram illustrates an example illumination method. For example, a portion of the field of view (FOV) of the detection system is illuminated at any given time to minimize the illuminated area of ​​the target. This can reduce the probability of false detections. In one aspect, to image the entire FOV of the detection system, the illumination system illuminates a series of images of a small sub-region (referred to as the region of interest (ROI)) covering the FOV. Thus, the imaging system within the inspection system (e.g., imaging system 512) can acquire multiple images with the partially illuminated FOV and later electronically combine these multiple images into the final image. This combination can also be referred to as stitching. For example, in... Figure 6 In this system, the imaging system may have a field of view (FOV) 602, and four subsequently acquired images 604, 606, 608, and 610 (marked in gray) having partially illuminated regions of interest (ROIs) are acquired and combined into a composite image of the entire FOV 612. In some embodiments, the ROI portion of each image may be extracted and combined into a stitched full-field image 612 covering the entire FOV of the detection system.

[0117] In some embodiments, the use of a DMD device or an LCD device allows for electronic control of the ROI, including control of the ROI's position and size. Furthermore, the ROI can have any shape, and its position does not necessarily have to follow a specific pattern. Figure 6The pattern depicted is from left to right. Furthermore, the sizes and shapes shown herein are merely illustrations of one exemplary implementation of the ROI. It is understood that ROIs can take different sizes and shapes, and subsequent ROIs can have different shapes. Additionally, ROIs can partially overlap and have irregular shapes. Moreover, although the composite image 612 is described as covering the entire FOV of the detection system, it is understood that multiple portions of the FOV can be covered, and the stitched composite can cover a portion of the FOV.

[0118] Figure 7 The diagram illustrates the sequence of operations for reconstructing a synthetic image based on subsequently acquired images of the region of interest, according to some embodiments. Figure 7 In this process, illumination spots 702a, 702b, and 702c are illuminated and processed as regions of interest (ROIs). Each illuminated image FOV 704 includes a ROI 706 and the remaining FOVs. In one aspect, since only the ROIs are needed, the remaining data relating to other parts of the FOV 708 can be discarded. Thus, collection of each illuminated ROI 1-n (which is subsequently stitched together to form a composite image 710) is permitted. In some aspects, discarding data from non-ROI regions (pixels) can provide additional benefits, such as maximizing data bandwidth by efficiently using the data bus to transmit only information related to the ROI pixels.

[0119] The location of the ROI can be controlled electronically. A camera with a large field of view can be positioned such that multiple ROIs are located within its FOV. In one aspect, during image acquisition, multiple full-field images with ROIs in multiple different locations are acquired. Post-processing can be performed to extract data related to the ROI or to block data related to the remaining FOV. Once the composite images 710 are stitched together, the composite images are ready to be processed for particle detection.

[0120] In some embodiments, while this method may require capturing multiple images (n images to be stitched together to produce a composite image), it can provide high accuracy in detecting contaminants, as will be further described herein. To compensate for any processing delays caused by capturing additional images, a high-speed image sensor can be employed. Furthermore, the process can employ a field-programmable gate array (FPGA) (which can act as a "gatekeeper") to prevent data unrelated to the ROI being processed. Thus, the FPGA can store pixel data within a designated ROI, and all other data can be discarded (or not written to memory). Moreover, such a process can be performed in real time, and the CPU can subsequently process only the complete (stitched) image as soon as the image sensor can read the image data.

[0121] Figure 8 The figure illustrates a schematic diagram of a data acquisition preprocessing pipeline according to some embodiments. Imaging device 802 can collect image data relating to the entire field of view (FOV) of the imaging device (or detector device within the imaging system). FPGA 804 can be pre-programmed to process or collect pixel data relating to a region of interest. This can be a specific region of interest or a series of regions of interest covering part or all of the FOV. As previously noted, FPGA 804 can be programmed to select ROI data for processing, or to process more efficiently, only to reject or discard pixel data that does not relate to the ROI in question / under consideration. After collecting the necessary pixel data for a predetermined number of ROIs, FPGA 804 can stitch together the composite image 710.

[0122] Figures 9A to 9C The figure shows a schematic diagram of an illumination and observation system according to some embodiments in a cross-section of an illustration of the region of interest (ROI). Figure 9A The figure illustrates a simplified diagram of the illumination and observation system. In Figure 9, an illumination beam 908 is incident at an angle β onto a photolithographic pattern forming apparatus 902 (e.g., a photomask). A detector (such as a camera) may have a field of view 920 that receives light reflected off the surfaces of the photolithographic pattern forming apparatus 902. Such reflections may include reflections 922 exiting from a first surface (e.g., a glass surface or rear surface 910), where contaminants / particles may be detected, and another reflection 924 exiting from a second surface 930 (e.g., a front surface, where pattern 904 may be detected). As a result, the detector may receive multiple reflections, including interference stray light (e.g., another reflection 924). This can lead to false alarms, where the detector may determine the presence of particles when no particles are present, or in the case of erroneously detecting multiple particles.

[0123] Therefore, it is desirable to divide the detector's field of view (FOV) into multiple regions of interest (ROIs) 926 and to individually illuminate each ROI with the illumination beam 908. By refining / segmenting the FOV into different ROIs and illuminating each ROI individually, reflections departing from other surfaces of the photolithographic patterning apparatus (e.g., the second surface 930 where pattern 904 is located) can be avoided. For example, this implementation avoids illumination of a portion 928 (which would typically be illuminated under direct illumination). By doing so, the detector will not receive stray light from the segment 928 at the ROI. Instead, potential interference reflections can be directed toward other parts of the FOV located outside the ROI. The detector can then be programmed to handle reflections only corresponding to the ROI, as will be described separately herein.

[0124] As noted herein, irradiating the entire photolithographic patterning apparatus can be problematic because light reflected from the pattern on the front side of the apparatus may be observed by the imaging system detector and cause false alarms. Stray light may be considered as all unwanted light entering the detection system. Because light from the diffraction pattern (e.g., pattern 904) is unwanted, it can be classified as stray light. This stray light can be converted into a false alarm indication of the presence of particles / contaminants on the surface of the photolithographic patterning apparatus.

[0125] In some respects, despite advances in particle detection tools for determining particle location and size, these tools may not provide sufficient advancement in reducing false alarms. Remedial measures can be taken, including using different wavelengths or signal amplitudes to reduce the effect or influence of stray light signals (e.g., reflected signals from diffraction patterns on the front side of the photolithographic patterning apparatus). According to some embodiments, for single-band or frequency band illumination systems, the lateral position of light reflected from the pattern (as observed by a camera) can be controlled by the properties of the diffraction pattern (e.g., diffraction order exit angle), wavelength, and incident angle of the incident radiation. Because diffraction effects are wavelength-sensitive, “stray light” and light scattered / diffracted by particles can be distinguished by analyzing the acquired images using illumination with different spectral components. In images acquired using different spectral bands, the particle position can be constant, and the position of “stray light” can exhibit wavelength dependence from the detector’s perspective.

[0126] In some embodiments, it is desirable to eliminate any interference signals generated by the illuminated diffraction grating. This can be accomplished by identifying regions of interest (ROIs) that are illuminated individually and sequentially. The images of the ROIs are then processed and stitched together to construct a composite image of all the ROIs together.

[0127] In one aspect, the ROI illumination can be used to illuminate a desired area on a first side (e.g., the rear side) of the photolithographic patterning apparatus while simultaneously eliminating interference signals generated by illumination reflections from the opposite side (e.g., the front side) of the photolithographic patterning apparatus. This allows the imaging apparatus to process light reflected solely from the ROI (at the illuminated rear side) without interference from any reflected light originating from the front side.

[0128] In some embodiments, an illumination diagram that leads to a reduced false alarm detection rate may be provided in the system, which is composed of an imaging system constructed from a pixelated image detector combined with a telecentric imaging system, or composed of an optical engine coupled to a DMD module and then a telecentric projection system.

[0129] As will be further described herein, bilateral inspection can also be implemented to increase throughput and speed up inspection time. Therefore, embodiment 940 illustrates bilateral inspection, in which the rear side and the surface film side 942 can be inspected. Similar to the detection of contaminants on the rear surface 910, the detection of the surface film side 942 can generate stray light in the same manner, where stray light may be reflected away from the particles 944 and may also be reflected away from the pattern 904. Therefore, in embodiment 940, the detector's field of view 920 and the configuration of the region of interest 926 can be similarly applied.

[0130] Figure 9B The figure illustrates a general schematic diagram of ray propagation according to some embodiments, wherein only one ROI is simultaneously illuminated and observed by the imaging system.

[0131] In some embodiments, a collimated illumination beam is incident on the rear surface of a photomask at an angle β. In one embodiment, the photolithographic patterning apparatus 902 may have a pattern 904 on one side (e.g., the front side) and one or more particles on the opposite side (e.g., the rear side). The photolithographic patterning apparatus 902 may receive the illumination beam 908 at an angle β. Imaging optics (not shown) (such as imaging system 512) may be positioned perpendicular to the rear surface (e.g., rear surface 910). Imaging system 512 may collect light from region 914 (wherein the region of interest (ROI) is identified). In this way, two separate / separate regions are illuminated on two opposite sides of the photolithographic patterning apparatus. For example, here, region 914 is illuminated on the rear side of the photolithographic patterning apparatus 902, while region 916 is illuminated on the front side of the photolithographic patterning apparatus 902. This ensures that region 918 is not illuminated. Using lateral illumination at an angle β allows illumination of region 916 while avoiding illumination of region 918, thus reducing / eliminating interference from any light scattered / reflected from region 918. In other words, interference is reduced by not illuminating the front side of the photolithography patterning apparatus 902, as this eliminates any light reflected from the front side of the mask at region 918 of interest. Effectively, the camera collects light from the unilluminated region (labeled 918) on the front side of the mask while simultaneously illuminating region 916 on the front side of the photolithography patterning apparatus 902.

[0132] In some embodiments, to minimize the false alarm detection rate, the observation and illumination system angles (β) and the width of the illuminated region 914 can be set such that regions 916 and 918 are mutually exclusive. In one aspect, for a fixed region size W, increasing β results in a larger interval between regions 916 and 918. For a small projection angle β, the width of the observed region w must be adjusted to ensure an interval between regions 918 and 916. Alternatively, reducing the numerical aperture (NA) of both systems can reduce the size of regions 918 and 916, but at the cost of reduced resolution of the imaging system.

[0133] In one aspect, FPGA 804 can discard pixel data from region 912, and allow composite images consisting only of images captured within the ROI at region 914 to be stitched together. In another aspect, the mask depth (d) can indirectly control the width of region 918, since the width of region 916 changes very slowly with increasing (d). Therefore, in one aspect, the mask depth can be taken into account when determining the size of the ROI. For example, the thickness of the mask (for back-side or front-side inspection—the distance from the mask to the pattern—can define the width of the ROI (e.g., region 914) by the illumination angle and the numerical aperture of the projection / observation optics).

[0134] The current illustration of the system is only one exemplary embodiment, and those skilled in the art will understand that other modifications / configurations may be possible. In one example, assuming the use of a spectrally sensitive detector and illumination system capable of simultaneously illuminating any selected ROI in multiple separate spectral channels, the imaging system 512 can simultaneously acquire data from multiple ROIs. This helps increase the throughput of the system without causing any delay.

[0135] Furthermore, the shape of ROI 1002 does not need to follow a specific predetermined shape, such as in... Figure 10 As discussed separately, the shape, location, and overlay of the ROI can be varied within FOV 1004 and can, for example, depend on the shape of the target object. For example, in the case of an ROI shape in a deep ultraviolet (DUV) film, where the film shape has the highest gradient, the ROI shape can be part of an ellipse, due to the limited depth of field (DOF) of the imaging system, and the requirement for illumination and observation of mutually exclusive areas on the film and mask from the imaging system's perspective.

[0136] In one embodiment, the shape gradient of the film can be controlled by the thickness, mass, and tension of the film. During manufacturing, the film can be pre-tensioned and can have a surface sag not exceeding a certain value specified by the manufacturer (e.g., 0.5 mm, but other values ​​are also possible). To obtain information about the size of the particles (e.g., particle 906), the imaging system may be required to have sufficient resolution to detect the size information. However, increasing the resolution of the imaging system may increase the system's NA (numerical aperture), and this may reduce the system's depth of focus (DOF = ... Therefore, a system with single-micrometer-level resolution will have a DOF of approximately a few micrometers. Considering that the shape of the film may be a three-dimensional composite curve that intersects additionally with the planar surface of the detector passing through the imaging system, the sharply imaged portion of the film (within the DOF) can be formed not within... Figures 9A to 9CThe shape of the rectangle depicted. One such example could be a curved shape as depicted in 1002.

[0137] Figure 9C The diagram illustrates, according to some embodiments, Figure 9B An enlarged view of box 950 depicts the main rays (dotted lines) and edge rays (continuous) of the illumination system 952 and the observation system 954. As described herein, the purpose of this disclosure is to illuminate a region on a first surface (e.g., a rear surface) of a photolithographic pattern forming apparatus that is different from the irradiated region on a second surface (e.g., a front surface). By not irradiating the front surface at the same location as where the rear surface is irradiated, stray light reflected from the pattern found on the front surface can be reduced or eliminated. According to one aspect, to avoid overlap between the illumination and observation systems, the edge rays of each system need not intersect on the front side of the mask, thereby creating two mutually exclusive regions 916 and 918, respectively.

[0138] Figure 11A The figure illustrates an optical-mechanical schematic diagram of a system, according to some embodiments, capable of achieving high-resolution imaging of the entire photolithographic pattern forming apparatus using multiple regions of interest.

[0139] As the size of printed features continues to decrease, there is a need to detect particles with dimensions at the single-micrometer level. To provide appropriate particle size determination independent of the particle's scattering and reflection properties, the following imaging methods can be employed. Sufficient photodetectors (NAs) are required to achieve the desired resolution in an object-space imaging system. Most commercially available detectors follow the shape factor standard of camera detectors. In one aspect, the detector can be 24x36 mm in size and has a small-format film frame, which, combined with the measured resolution of tens of megapixels, results in a single photosensitive area ranging from 1.5 μm to 10 μm in size. Because camera pixels are typically larger than the smallest particle to be detected, systems with a magnification greater than 1x can be used. This (combined with the typical size of the detector) means that the FOV of a typical imaging system is several times smaller than the size of a photolithographic patterning apparatus, i.e., a fraction of the size of the photolithographic patterning apparatus. Scanning or stepping systems can be used to image the entire mask / film. Therefore, the imaging system described below is proposed as a combination of the following two: the SUB-FIELD-OF-VIEW illumination strategy, i.e., the sub-field of view illumination strategy (ROI + stitching); and the illumination strategy that minimizes the false alarm rate.

[0140] Combining XYZ relative scanning between the mask / film and the irradiation and observation system allows for the inspection of the entire surface of the mask / film. Figure 11A An exemplary embodiment of such a system is schematically depicted below. Figure 11A The figure illustrates the operation of this proposed imaging system.

[0141] In one aspect, the relative XYZ positions between the lithographic patterning apparatus, the illumination and imaging system are controlled by mechanical actuators. For example, the lithographic patterning apparatus 1102 can be placed on an XYZ platform 1104, and the illumination and observation systems 1106 and 1108 are respectively fixed. The FOV of the imaging system covers a small area of ​​the lithographic patterning apparatus 1102 and is schematically depicted as 1110 in FIG. 11. Within each FOV, multiple ROI images can be acquired. Each ROI image can have a small area 1111 illuminated by the illumination system. Multiple ROIs can be combined using the methods described above to form a composite or stitched image of the FOV. In one aspect, a mask is actuated and the image acquisition process is repeated. The combined FOV can be used to detect particles.

[0142] In some examples, the entire lithographic patterning apparatus or only several parts thereof can be scanned. Furthermore, ROIs and FOVs can be stacked or mutually exclusive, depending on the specific application requirements. In some respects, mutually exclusive ROIs and FOVs contribute to increased productivity (e.g., reduced measurement time equals higher throughput). Additionally, stacked ROIs and FOVs can be used to improve stitching, as observed particles in both datasets can be used to compensate for system defects such as vibration-related image shift, platform accuracy, degree, etc. In one respect, the combined ROI does not necessarily need to cover the entire FOV. Given the detector size and the magnification of the optical system, the size of the FOV can be calculated. For example, if DX and DY are the width and height of the FOV, respectively. Given the mask width w... reticle and height h reticle In this case, multiple FOVs in the x-direction can be calculated as follows:

[0143] )

[0144] Where: INT is the rounding operation towards positive infinity, and similarly,

[0145] )

[0146] Where: INT is the rounding operation towards positive infinity, i.e., the rounding operation.

[0147] In one aspect, the system uses ROI irradiation to illuminate different areas on the front and rear sides of the photolithographic patterning apparatus, which can reduce the false alarm detection rate. This can help reduce delays during the inspection process by searching for locations where contaminants that may not be present or are incorrectly identified. In another aspect, irradiation is performed using an arbitrarily selected irradiance level, and high dynamic range (HDR) data is acquired using a camera and / or projector. In yet another aspect, the flexibility associated with the stitching algorithm involving shape selection of the overlay area (specifically, ROI) allows for individually controllable shapes, and the overlay area can be controlled by the ability to electronically control the position of the irradiated area.

[0148] Figure 11B The figure illustrates an inspection method 1100 according to some embodiments. It should be understood that the operations illustrated in method 1100 are not exhaustive, and other operations may be performed before, after, or between any of the illustrated operations. In various embodiments of this disclosure, the operations of method 1000 may be performed in different orders and / or may be varied, or the operations of method 1000 may be performed using means different from those described as examples.

[0149] Operation 1112 includes using a radiation source (e.g., a radiation source) to generate a radiation beam to irradiate a first surface of an object, wherein a first parameter of the beam defines a region of the first surface of the object. In this regard, the first region may be region 914 located behind the photolithographic pattern forming apparatus 902.

[0150] Operation 1114 includes irradiating a second surface of the object, a second parameter of the beam defining a region of the second surface, wherein the second surface is located at a different depth level within the object than the first surface. In this respect, the second region may be region 916 located on the front side of the photolithographic pattern forming apparatus 902. In one example, the system may include a camera and at least one illumination unit for measuring particles located on the surface of the mask. Therefore, as described herein, stray light reflected from patterns on different surfaces of the mask can be acquired by the detector, and thus false alarms may occur. According to embodiments of this disclosure, such stray light is processed such that it does not interfere with light reflected from particles found on the surface of the mask.

[0151] Operation 1116 includes defining the field of view (FOV) of the detector. This field of view may be field of view 602, which the detector can capture at any given moment when imaging the photolithographic pattern forming apparatus (e.g., an object). Furthermore, this FOV captured by the detector may belong to the rear side of the object and includes, for example, the region 914.

[0152] Operation 1118 includes receiving radiation from the first region of the first surface at the detector. This could be receiving scattered light from particles or contaminants detected at the rear side of the photolithography pattern forming apparatus 902.

[0153] Operation 1120 includes using a processing circuitry system (e.g., CPU 806) to discard image data not received from areas not originating from the first surface. In this regard, as described herein, to minimize or eliminate false alarms or interference from reflections from objects not originating at the rear surface of the photolithographic patterning apparatus (and specifically, at the illuminated ROI), the operation may discard any other received data not identified as part of the ROI image data. For example, in FIG. 9, areas 914 and 916 are illuminated, while area 918 is not. Therefore, the detector can receive radiation from areas 914 and 916. However, based on this operation, radiation received from area 916 will be blocked. For example, FPGA 804 can receive coordinate data of the illuminated ROI and can act as a gatekeeper / gatekeeper by processing data from those coordinates or blocking any other data not originating from those coordinates.

[0154] Operation 1122 includes constructing a composite image comprising image data from an entire region of the first surface. In this way, using each processed ROI, processor 804 can stitch together all image data for each corresponding ROI and produce a composite image comprising all processed ROI data. This ROI illumination technique, as described herein, allows for the extraction of data from the rear surface of the photolithographic patterning apparatus while simultaneously eliminating interference signals from multiple patterns and other objects placed on the front surface of the photolithographic patterning apparatus. Furthermore, according to some aspects, the stitched image as a whole can now be free of such interference and depict a more accurate representation of contaminants / particles found on the rear surface of the photolithographic patterning apparatus.

[0155] In some embodiments, there may be an irradiation operation of a second region on the first surface of the object using the radiation source; and the reception of radiation scattered at the second region on the first surface at the detector.

[0156] In some embodiments, there may be processing operations of the image data received from the second area of ​​the first surface using the processing circuitry system; and discarding image data received from any other area within the FOV.

[0157] In some embodiments, the processing circuitry may be used to construct a composite image, which includes image data from a first region on the first surface and image data from a second region on the first surface. The Region of Interest (ROI) may be sequentially illuminated (i.e., two or more regions of the first surface are illuminated), the two or more regions covering the Field of View (FOV).

[0158] In some embodiments, there may be an operation to construct a synthetic image corresponding to the FOV.

[0159] In some embodiments, there may be a determination operation based on the synthesized image to determine whether a particle is located within the FOV at the first surface of the object.

[0160] Region 918 can be described as a third region of the second surface, the third region being defined as having a region corresponding to a portion of the first region that is not illuminated when observed from the detector while the first region is illuminated. Here, the third region may be adjacent to the second region, and the third region and the second region do not overlap.

[0161] In some embodiments, the width of the illumination beam 908 may be defined by two illumination cones (covering areas), each cone comprising two edge rays and one main ray; and the width of the ROI, region 914, may be defined by two observation cones, each cone comprising two edge rays and one main ray. For example, in FIG9, the main ray of the illumination cone and the main ray of the observation cone may intersect at the first surface of the object, and the edge rays of the illumination cone and the edge rays of the observation cone may not intersect at the second surface of the object.

[0162] Figure 12 The figure illustrates an optomechanical schematic of a particle detection system 1200 according to some embodiments. In one aspect, these systems employ a high-resolution imaging system positioned perpendicular to the surface of a photolithographic pattern forming apparatus / coating to inspect for contaminants, as described herein. In one aspect, the physical constraints of the image detector and imaging optics can generate a field of view (FOV) for the system (which is a mask / coating or an observation-illumination system), actuated to enable image acquisition at any selected location. The target (mask / coating) area covered by the imaging system can be referred to as the FOV, and a series of FOVs distributed across the target object will be sequential images, i.e., consecutive images. It is desirable that the area illuminated by the projector is equivalent to the area imaged by the camera's field of view (FOV). A minimum area can define the system's FOV if one is smaller than the other.

[0163] In some embodiments, system 1200 includes an imaging system 1202, which includes an image detector 1204 and an imaging lens 1206. Imaging system 1202 also includes an optical axis 1208 perpendicular to the mask / coating surface 1210. System 1200 may also include an illumination system 1212, which includes a light engine 1214 and a projection lens 1216. System 1200 illustrates different regions covered by different systems and their intersections. For example, in some aspects, system 1200 defines a region 1218 on the mask / coating surface 1210 illuminated by illumination system 1212. In some aspects, system 1200 also defines a region 1220 covered by imaging lens 1206 and including a region 1222 that serves as the field of view (FOV) of image detector 1204. As will be understood from various embodiments of this disclosure, the FOV may be adjustable and may include one or more regions of interest (ROIs).

[0164] Figure 13 The diagram illustrates a grid of rectangular field of view 1300 covering the entire surface of a photolithographic patterning apparatus 1302 according to some embodiments. In one aspect, the shape of the FOV or the ROI within the FOV can depend on various factors and may not always be uniform across the entire photolithographic patterning apparatus. Therefore, the organization, shape, total number, and coverage area of ​​the FOVs can depend on the configuration and application, and can differ between photomasks and thin films. In some aspects, the rectangular field of view 1300 can be divided into M x N FOVs 1304. Each FOV 1304 can be divided into several ROIs that can be individually irradiated. The ROIs can also be irradiated sequentially, such as... Figure 14 The other illustration is shown in the image.

[0165] Figure 14 The figure illustrates radiation operation 1400 within the camera field of view (FOV) of different regions irradiated on the photolithographic patterning apparatus 1402 according to some embodiments. In some embodiments, to provide conditions for minimizing false alarm detection rates, a series of N images can be recorded in each FOV. Figure 14In the example provided, a series of eight images were recorded between timest0 and t7. Here, the eight sub-aperture areas of interest (ROIs) (i.e., ROI1 to ROI8) are stitched together to form a composite image that depicts the entire field of view (FOV X, Y 1404). As previously noted, the ROIs need not be rectangular nor need to cover the entire FOV. According to some embodiments, the radiation operation 1400 may begin by irradiating the first ROI 1406 within the FOV 1404 at an initial timet0, followed by irradiating the second ROI 1408 at timet1, then the third ROI 1410 at timet2, then ROI 1412 at timet3, then ROI 1414 at timet4, then ROI 1416 at timet5, and finally ROI 1420 at timet7.

[0166] In some embodiments, during measurement, the imaging system iteratively acquires ROI images for each FOV. The organization, size, and orientation of the ROI and FOV are configurable and depend on optomechanical configuration parameters such as lens field coverage, detector size, magnification, angle between the illumination and observation systems, mask material, illumination wavelength, etc.

[0167] like Figure 15 As illustrated in the diagram, from a system performance perspective, minimizing the false alarm rate is crucial in some embodiments. For example, adjustments can be made to the angle between the optical axes of the illumination and observation systems, as well as the orientation and region optimization of multiple individual ROIs. In some embodiments, due to the geometric relationships between the illumination, mask, and observation modules, a common area between the illumination and observation subsystems can be imaged. To minimize the area illuminated by the projection subsystem, the transformation between the local coordinates of the illumination system 1504 and the local coordinates of the imaging detector 1506 can be determined to precisely adjust the size, location, and orientation of the area illuminated by the illumination system on the photolithographic pattern forming apparatus 1502. This can be accomplished, for example, by finding a transformation T that associates the local coordinates (x', y', z') of the illumination system with the local coordinates (x, y, z) of the image detector.

[0168] The parameters of transformation T can depend on the position and orientation of the system components. In some embodiments, manual adjustments can be performed on the area irradiated by the irradiation system. However, in other embodiments, an operator-independent method is employed to provide repeatable and objectively measurable results.

[0169] Figure 16The figure illustrates a proposed calibration method 1600 according to some embodiments, used to calibrate patterns 1602 and 1604 of an observation-illumination system using a sequence of projected Gray code patterns. In some embodiments, an automated calibration process is used to identify the relationship between the local coordinates of the observation and illumination systems. In some embodiments, the illumination system illuminates the measured surface using a series of patterns designed to produce a unique temporal intensity distribution in each photosensitive element (e.g., pixel 1606 and pixel 1608) of the image detector. By analyzing the intensity distribution acquired by each pixel, corresponding points in the illumination module can be identified. Thus, by analyzing the intensity acquired by the camera photosensitive elements, the calculation of the transformation matrix can be possible, which associates the local coordinate system of the camera with the local coordinate system of the illumination module.

[0170] exist Figure 16 In the example illustrated, a computer-controlled illumination system capable of generating numerous patterns can be configured. In some aspects, the illumination system can be constructed from a controllable special light modulator (SLM), a digital micromirror device (DMD), or by depositing patterns directly onto a substrate. In each of the considered embodiments, the illumination system illuminates the surface using any selected pattern, such as pattern 1602 and pattern 1604.

[0171] According to some embodiments, in Figure 16 In this model, shadow pixels depict unlit pixels and non-shadow pixels depict lit pixels. By analyzing the temporal distribution of intensity (in pixels), it is possible to decode many pixels encoded as dark (light off = 0 bit) and bright (light on = 1 bit). In some cases, to encode 8 bits, it would be necessary to acquire 8 images.

[0172] Figure 17 The figure shows the temporal intensity distribution collected during calibration method 1600. Figure 17 The example decoded sequences are shown as pixel 1606 (1*t0+0*t1+0*t2+0*t3+1*t4 = 1*1+0*2+0*4+0*8+1*16 = 17) and pixel 1608 (1*t0+0*t1+0*t2+1*t3+0*t4 = 1*1+0*2+0*4+1*8+0*16 = 9). This is effective because each pixel of the projection system can have its own unique code number, and thus, by detecting these code numbers, the coordinates x and y of the projector in the image captured by the camera can be calculated. Therefore, this method allows for the identification of x coordinates in a set of n images and the identification of y coordinates in another sequence having a pattern perpendicular to the first sequence (e.g., horizontal and vertical orientation).

[0173] In one example, the projected pattern can be constructed such that it produces a unique temporal pattern in pixels 1606 and 1608 and allows for a unique identifier for the horizontal axis. To perform vertical calibration, a set of Gray codes is projected and recorded in the image sequence acquired at t0 to t4. In some embodiments, the following patterns can be projected: Gray codes, binary codes, scanned “pixels,” scan lines, regular one-dimensional or two-dimensional periodic patterns, sufficiently long random patterns, intensity-coded patterns (such as one-dimensional intensity ramps), frequency-modulated patterns, spectral modulation patterns (in the case of spectrally sensitive projectors), and so on.

[0174] In some embodiments, a pattern can be used to achieve the objectives described above. For example, a two-dimensional sinusoidal pattern can be projected by the illumination system. Such a pattern will have a unique phase distribution in the x and y directions, and thus will allow for explicit calculation of the parameters of the transformation T between the camera and the projector. Analysis of such a pattern can be performed in the Fourier domain, where spatial spectral operations are applied, and the phase distributions of the two sinusoidal distributions can be reconstructed, thus allowing for correlation between the local coordinate systems of the camera and the projector. In one embodiment, a multiple-image method for calibration is preferred from the perspective of data analysis and overall reliability, and is further described herein below.

[0175] Calibration can be performed between the imaging system and the projection system. In some embodiments, calibration can result in the elimination of human input during the process of identifying the correspondence between the coordinates of the illumination and observation subsystems. This allows the system to be self-sufficient, more reliable, and calibrated at a faster speed. Objective, quantitative calibration of the illuminated area can be achieved to match the field of view of the imaging detector. Furthermore, the proposed method can be used to minimize the illuminated area (which in turn reduces the false alarm detection rate) and automate diagnostic procedures to remotely and periodically check the system status.

[0176] Figure 18 The figure illustrates a system configuration of an imaging system 1800 according to some embodiments. The system configuration and the associated method of the observation-illumination system may rely on independent, parallel acquisition of images for particle identification purposes.

[0177] Reducing the size of the printed pattern often imposes stringent cleanliness requirements on the lithography machine and the lithographic patterning apparatus. In some embodiments, optical methods for identifying contaminants are used due to the non-contact nature of light-based measurements. In one aspect, the resolution of the optical system is related to the wavelength and numerical aperture by the Abbe formula (i.e., d = λ / 2NA); where d is the resolution, λ is the wavelength, and NA is the numerical aperture of the system, and NA = nsinα.

[0178] In some embodiments, to construct a system capable of detecting particles as small as micrometers, an observation and illumination system with an appropriate numerical aperture is designed. Increasing the resolution of the imaging system may result in a decrease in the field of view due to physical limitations of photodetectors and cost-related factors (large NAs and large FOV lenses may be uneconomical for particle identification purposes). Depending on the spectral range, sensitivity, and specific system requirements, particle detection devices can be constructed using a single photosensitive element (scanning system), a pixelated charge-coupled device (CCD), or a complementary metal-oxide-semiconductor (CMOS) detector (imaging system).

[0179] In some embodiments, observation systems with large NAs can be used from the perspective of accuracy and repeatability in particle identification and size determination. In some embodiments, throughput requirements tend to favor optical systems with smaller NAs (which typically offer larger field coverage and therefore typically shorter measurement times). To meet these conflicting requirements of shorter inspection times under strict size determination constraints, doubling the number of illumination-detection systems can be a viable alternative. Because there is a linear relationship between measurement time and the number of illumination-observation systems used, using two or more imaging systems allows the measurement time to be reduced by a factor of two, i.e., by half.

[0180] In one embodiment, a pattern printed on a photolithographic patterning apparatus under adverse conditions may produce an image of a real object and light source, which can often be difficult to distinguish from particles and may contribute to an increased false alarm detection rate. The probability of false alarm detection may increase due to the multiplication of the illumination-detection subsystem, as light propagates within the mask, mask substrate, surface film, or the gap between the mask and surface film. The figure below illustrates an exemplary solution capable of simultaneously imaging the surface of the photolithographic patterning apparatus without increasing the risk of false alarm detection.

[0181] Figure 18The figure illustrates a system configuration of an observation-illumination system with simultaneous illumination and measurement according to some embodiments. In one aspect, spectrally separated imaging systems 1802 and 1804 can be used to optically isolate them, and the use of at least two systems operating in parallel allows for approximately simultaneous measurements without altering the error rate associated with false alarms.

[0182] In some embodiments, Figure 18 The figure illustrates an imaging system 1800 operating using two imaging systems. Imaging systems 1802 and 1804 are coupled to two illumination systems 1806 and 1808, respectively. Imaging systems 1802 and 1804 may have their optical axes perpendicular to the surface of the photolithographic pattern forming apparatus 1810, and image portions of the photolithographic pattern forming apparatus 1810 on their respective detectors. The illumination systems paired with the imaging systems illuminate the imaging area of ​​the photolithographic pattern forming apparatus 1810 and may provide conditions suitable for particle identification. Imaging system 1800 may employ spectral filters (not shown) with mutually exclusive passbands, which are incorporated into the optical system, i.e., the optical train, of the two imaging systems and work in conjunction with the emission spectrum of the illumination units.

[0183] exist Figure 19 Example transmission characteristics of the filters incorporated into imaging systems 1802 and 1804, and the corresponding emission spectra of the illumination units are provided. As illustrated, the emission bands of each system are located at different wavelengths (λ). In one aspect, the transmission spectra of the filters in the optical arrays incorporated into imaging systems 1802 and 1804 are configured such that they filter only the corresponding emission wavelengths. Because the two systems can operate in different spectral ranges, their operation is independent for the angle of view for detection of electromagnetic radiation. In some embodiments, because the light emitted by illumination system 1806 cannot be detected by imaging system 1804 and vice versa, the false alarm rate is related to the optomechanical configuration and specific properties of the individual illumination-observation system sets. In some aspects, to further minimize this error, the ROI illumination and stitching method described herein can be implemented.

[0184] According to some aspects, in order to capture the emission spectrum 1906 of the illumination system 1806, a transmission filter 1902 can be applied at the imaging system 1802. Similarly, in order to capture the emission spectrum 1908 of the illumination system 1808, a transmission filter 1904 can be applied at the imaging system 1804.

[0185] In some embodiments, the illumination system may employ a narrowband light source (such as an LED diode or a laser) or a broadband light source coupled with a narrowband / bandpass filter to illuminate the surface using electromagnetic radiation within the desired spectral range. The illumination system may employ the quantum efficiency of narrowband, long / short pass filters, or detectors to spectrally isolate any combination of multiple systems operating in parallel. Employing a filter with a FWHM (full width at half maximum) that matches the emission characteristics of the light source can be beneficial for signal-to-noise ratio (SNR) processing. In some aspects, if the filter is used with spectral transmission characteristics that match the diode emission (e.g., the filter transmission is wider than the diode emission), the light emitted by the diode can pass through, and the detected signal and S / N ratio are high. Alternatively, the bandpass filter may have a passband that only partially overlaps with the diode emission band, and therefore only a small portion of the light emitted by the diode can reach the object surface. Consequently, the signal will have a reduced S / N ratio distribution, i.e., a lower SNR distribution.

[0186] In some embodiments, Figure 18 and Figure 19 The implementation illustrated in the figure allows for independent, parallel data acquisition using multiple illumination-observation systems. In some aspects, the imaging systems can be optically isolated using the proposed spectrally separated illumination-observation strategy. In some embodiments, such optical isolation provides: (1) unobstructed data acquisition using multiple systems operating in parallel; (2) elimination of crosstalk between illumination-observation systems; (3) the false alarm rate is limited within the respective system and does not change with the number of parallel-operating systems; and (4) the multiple parallel-operating systems can share a field of view (FOV) and can simultaneously acquire different types of information, for example, using an observation system separated into two channels by a beam splitter, where the illumination system can illuminate objects from two directions using mutually separated spectral channels. This allows for the acquisition of data that will contribute to the depiction of differences between images and particles, due to the achromatic nature of scattering and the wavelength and direction dependence of diffraction phenomena. This is in Figure 20 and Figure 21 Another illustration is shown in the image.

[0187] Figure 20The figure illustrates an example of an imaging system constructed according to some embodiments, using a pair of panchromatic sensitive image detectors 2002 and 2004 separated by a dichroic beam splitter 2006 that receives radiation passing through an imaging lens 2008. The system 2000 may also include an illumination source 2010 illuminating region 2012 at a first wavelength λ1 and an illumination source 2014 illuminating region 2016 at a second wavelength λ2. According to some aspects, the imaging lens 2008 reads an image corresponding to the image region 2018. As previously noted, the illumination and detection can be performed relative to a photolithographic pattern forming apparatus 2020. The configuration of the system 2000 can reduce the number of devices used and the space occupied by the detection sensors.

[0188] exist Figure 21 In the middle, the system 2100 is composed of and Figure 20 The illumination settings of system 2000 are the same as those of system 2100. However, system 2100 may include a spectrally sensitive (color) detector 2102. According to some aspects, detector 2102 may be configured to detect a range of colors within a chromatogram and be able to distinguish between illumination from illumination sources 2010 and 2014.

[0189] Figure 22 The diagram illustrates the configuration of an irradiation-detection system according to some embodiments. The schematic diagram of the inspection system 2200 can be configured to perform simultaneous measurements on both sides of the photolithographic pattern forming apparatus. According to some embodiments, two systems operating in parallel on each side of the test object are depicted (e.g., systems 2202 and 2204 on one side and systems 2206 and 2208 on the other side), but the number can vary. Therefore, it can be appreciated that any number of measurement systems can be configured to perform measurements on either side.

[0190] Figure 23 The figure illustrates an example emission spectrum of a light source incorporated into an illumination system according to some embodiments. Similar to... Figure 19 , Figure 23 It can be illustrated Figure 22 The light source emission 2302 and their corresponding observation filter 2304. As previously noted, the emission spectrum of the light source can be incorporated into the illumination system.

[0191] While a separate illumination-detection system is described herein, this is merely an example of a possible implementation for addressing the increased throughput of inspection processing (without increasing the number of false alarm detection events). A system can be constructed that uses spectral separation to simultaneously acquire imaging data from different optomechanical configurations. For example, a particle detection system could be constructed using a dichroic beam splitter to achieve simultaneous observation of the field of view by two detectors, and using spectrally separated illumination units to illuminate the sample being measured from two directions. Because the scattering of light by particles can be considered achromatic and independent of the illumination direction, and the appearance of the image produced by the diffraction pattern embedded in the photolithographic pattern forming apparatus has a strong angular and spectral dependence, acquiring two images in mutually separated spectral bands using different illumination directions will significantly reduce the false alarm detection rate and contribute to improving system performance.

[0192] In another embodiment, polarization techniques can be employed to reduce the visibility of the diffraction pattern. This is because using a polarizer reduces the visibility of particles, thus the visibility of the diffraction pattern is observed to decrease at different rates. This also distinguishes the pattern image detected at the detector from the particles and enhances processing for false alarm detection. In other words, while not eliminating all false alarm images together, the polarization technique described herein can have a greater impact on the reflected pattern image than on the reflected particle image, thus making the particle image more prominent at the detector and thereby enhancing processing by allowing the detector to distinguish between the two signals.

[0193] Figure 24 The figure illustrates the diffraction properties of a patterned portion 2402 of a photolithographic patterning apparatus according to some embodiments, wherein electromagnetic radiation 2404 incident on the photolithographic patterning apparatus can be redirected to a detection system. Two boundary cases can be considered: 0% of the incident light will be redirected from the mask pattern to the detection system (e.g., as illustrated in Figure 9); or 100% of the light illuminating the mask pattern will be redirected 2406 to the detection system. In the second case, it is beneficial to help the detector distinguish between the light received from the particle 2408 (contaminant) and the light received from the patterned portion 2402.

[0194] According to some embodiments, the polarization-dependent diffraction efficiency of a mask pattern can be used to distinguish between light reflected from particles and light reflected by the mask pattern. The diffraction efficiency (the amount of light redirected by the diffraction structure along an arbitrarily selected direction) can depend on the incident angle of the incident radiation, the wavelength (λ), the polarization, and the surface profile of the diffraction structure. In some embodiments, the efficiency of such a diffraction grating is utilized in the direction of the receiving cone of the imaging system. The detection system can approximate the diffraction structure as a polarization-sensitive mirror whose reflection depends on the polarization of the incident radiation. For example, as... Figure 25 As illustrated in the diagram, the intensity of the particle reflection image can be reduced when light is polarized (compare particle intensity 2506, curve 2502 vs. 2504). For example, a reduction of up to 2 times can be achieved when a linear polarizer is installed. In other respects, in the case of pattern 2508, the intensity of polarized light can be reduced by up to 15 times after installing a linear polarizer (e.g., curve 2510 vs. 2512).

[0195] In some embodiments, installing a linear polarizer reduces the amount of light incident on the mask by up to two times, or half. Since light scattering by particles can be considered polarization-independent in a first approximation, the visibility of particles is reduced by two times, or half, with the linear polarizer installed. In some aspects, because the efficiency of the diffraction structure depends on polarization, the visibility of the mask pattern can be reduced by at least two times (experimentally measured to be approximately 15 times). In some aspects, for a given geometry of the irradiation system, this reduction can additionally be at least proportional to the square of the intensity transmission coefficient derived from the Fresnel equations. In some embodiments, the performance of arbitrary diffraction structures can be predicted analytically simply by directly solving Maxwell's equations, since no simplified scalar model is available.

[0196] In some embodiments, while light scattering typically performed by particles can be considered polarization-independent, i.e., unrelated to polarization, particles will scatter light in a polarization-dependent manner. Additionally, diffraction patterns can be designed to have diffraction efficiencies independent of the polarization state of the incident light (optimized for λ, incident angle, etc.). Therefore, this can be an additional design consideration for controlling light properties to reduce the probability of false alarms.

[0197] Exemplary coaxial inspection system

[0198] Figures 26 to 31The figure illustrates coaxial inspection systems 2600 and 2600' according to an exemplary embodiment. Coaxial inspection system 2600 can be configured to illuminate and detect particles on a mask and / or film at an adjustable yaw / roll (off-axis) illumination angle in a single cell. Coaxial inspection system 2600 can also be configured to illuminate and detect particles with structured light patterns and operate in bright-field or dark-field mode. Although in Figure 26 The coaxial inspection system 2600 is shown as a standalone device and / or system, but embodiments of this disclosure can be used in other optical systems, such as, but not limited to, lithography devices 100, 100' and / or other optical systems.

[0199] In some embodiments, the coaxial inspection system 2600 may include a polarization optical system. For example, such as Figure 31 As shown, the coaxial inspection systems 2600 and 2600' may include a polarization beam splitter 2630, a linear polarizer 2632, and / or a quarter-wave plate 2634. In some embodiments, the coaxial inspection system 2600 may employ one or more amplitude modulation (AM) and / or frequency modulation (FM) structured optical patterns 2615. For example, as... Figure 34 As shown, the coaxial inspection system 2600 can employ first, second, and third AM structured light patterns 2615a, 2615b, and 2615c.

[0200] like Figure 26 As shown, the coaxial inspection system 2600 may include an illumination system 2610, an optical axis 2612, an aperture stop 2620, a polarization beam splitter 2630, a focusing lens 2640, a converging lens 2650, a detector 2660, and / or a controller 2670. The coaxial inspection system 2600 may be configured to illuminate a mask 2602 and / or a coating 2607 using an illumination beam 2614, and to detect a signal beam 2616 scattered from the mask 2602 and / or the coating 2607 (e.g., from particles). In some embodiments, the illumination system 2610, aperture stop 2620, polarization beam splitter 2630, focusing lens 2640, converging lens 2650, and detector 2660 may be optically coaxial and aligned along the optical axis 2612.

[0201] Mask 2602 includes a rear side 2604 (e.g., unpatterned) and a front side 2606 (e.g., patterned). In some embodiments, mask 2602 may include a mask actuator 2603 (e.g., an XYZ translation platform) configured to provide adjustable translation relative to coaxial inspection system 2600. In some embodiments, all the aforementioned components of coaxial inspection system 2600 may be housed within a single housing 2608, for example, having a housing actuator 2609 configured to provide adjustable translation along optical axis 2612 relative to mask 2602 and / or surface film 2607 for focusing and defocusing the illumination beam 2614 on mask 2602 and / or surface film 2607.

[0202] Illumination system 2610 can be configured to transmit illumination beam 2614 along optical axis 2612. Illumination system 2610 may include electro-optical illumination module 2611, which is configured to electronically control illumination beam 2614. For example, electro-optical illumination module 2611 may control and / or adjust the numerical aperture (NA) of illumination beam 2614 (e.g., NA = n∙sin(θ), where θ is the maximal opening half-angle, and sin(θ) ≈ D / 2f, where D is the entrance pupil diameter and f is the focal length). In some embodiments, electro-optical illumination module 2611 may generate structured light patterns 2615. For example, electro-optical illumination module 2611 may include digital micromirror device (DMD), liquid crystal modulator (LCM), spatial light modulator (SLM), and / or combinations thereof to embed illumination beam 2614 having one or more structured light patterns 2615.

[0203] In some embodiments, the illumination beam 2614 may include one or more structured light patterns 2615. For example, such as Figure 34 and Figure 35 As shown, the illumination beam 2614 may include one or more AM and / or FM structured light patterns 2615a, 2615b, 2615c. In some embodiments, the structured light pattern 2615 may include AM and / or FM with a spatial frequency of less than 50 cycles / mm. For example, as... Figure 28 and Figure 30As shown, AM and / or FM can have a spatial frequency of less than 20 cycles / mm to approximate a non-apoptotic (e.g., 2806, 3006) modulation transfer function (MTF) distribution (e.g., a deviation of less than 6% for a quarter-disc aperture 2622; a deviation of less than 2% for a crescent aperture 2626, etc.). In some embodiments, the illumination beam 2614 may include multiple narrow spectral bands. For example, the illumination beam 2614 may include a blue visible (VIS) spectral band (e.g., about 400 nm to 420 nm), a green VIS spectral band (e.g., about 520 mm to 540 mm), and / or a red VIS spectral band (e.g., about 620 mm to 640 mm).

[0204] Aperture stop 2620 can be configured to select a portion of illumination beam 2614. Aperture stop 2620 may include apodization stops (e.g., radially tapered and / or tapered neutral density filters). In some embodiments, aperture stop 2620 may include multiple apodization stops. For example, as... Figure 27 and Figure 29 As shown, aperture stop 2620 may include apodized quarter-disc aperture stop 2622 and / or apodized crescent aperture stop 2626.

[0205] like Figure 27 As shown, the coaxial inspection system 2600 may include an aperture stop 2620 having an apodized quarter-disc aperture stop 2622 and a quarter-disc mask 2624. The apodized quarter-disc aperture stop 2622 may be configured to transmit a portion of an illumination beam 2614 (e.g., a structured light pattern 2615), and the quarter-disc mask 2624 (e.g., opaque) may be configured to block the illumination beam 2614. In some embodiments, in a bright-field mode (e.g., an unblocked central illumination beam), the apodized quarter-disc aperture stop 2622 may be configured to transmit the central portion of the illumination beam 2614 and provide an angle-insensitive off-axis illumination beam 2614 toward the mask 2602. For example, the apodized quarter-disc aperture stop 2622 may be rotated about an optical axis 2612 (e.g., in 90-degree increments) to provide a bright-field image of the region of interest (ROI) (e.g., a particle) on the mask 2602. In some embodiments, multiple bright field images of the ROI can be captured at different illumination angles (e.g., via an adjustable aperture stop 2620), and the multiple bright field images can then be reconstructed and digitally stitched together.

[0206] Figure 28 It is MTF2802 relative to Figure 27The graph 2800 shows the spatial frequency 2804 of the coaxial inspection system 2600 (e.g., with a quarter-disc aperture 2622). For example, MTF 2802 indicates how the coaxial inspection system 2600 handles different spatial frequencies (e.g., period / mm). For example, MTF 2802 specifies the response to a periodic sinusoidal pattern (e.g., in the case of spatial frequency 2804) transmitted through the apodized quarter-disc aperture 2622, as a function of the pattern's spatial frequency (period) and orientation. Figure 28 The MTF distribution of the non-apoptotic circular aperture 2806 (solid line) shown (e.g., NA = 0.3, at λ = 550 nm) can be compared with the MTF distribution of the apodized quarter-disc aperture 2622 (dashed line) (e.g., NA = 0.1, at λ = 550 nm). For example, at resolutions below 20 cycles / mm (e.g., 50 μm), the response of the apodized quarter-disc aperture 2622 approximates that of the non-apoptotic circular aperture 2806 with a deviation (error) of less than 6%.

[0207] like Figure 29 As shown, the coaxial inspection system 2600 may include an aperture stop 2620 having an apodization crescent aperture stop 2626 and a crescent mask 2628. The apodization crescent aperture stop 2626 may be configured to transmit a portion of an illumination beam 2614 (e.g., a structured light pattern 2615), and the crescent mask 2628 (e.g., opaque) may be configured to block the illumination beam 2614. In some embodiments, in a dark-field mode (e.g., a blocked central illumination beam), the apodization crescent aperture stop 2626 may be configured to block the central portion of the illumination beam 2614 and provide an angle-sensitive off-axis illumination beam 2614 toward the mask 2602. For example, the apodization crescent aperture stop 2626 may be rotated about an optical axis 2612 (e.g., in 90-degree increments) to provide a dark-field image of the ROI (e.g., a particle) on the mask 2602. In some embodiments, multiple dark-field images of the ROI can be captured at different illumination angles (e.g., via an adjusted aperture stop 2620), and the multiple dark-field images can then be reconstructed and digitally stitched together.

[0208] Figure 30 It is relative to MTF 3002 Figure 29A graph 3000 showing the spatial frequency 3004 of the coaxial inspection system 2600 (e.g., with a crescent-shaped aperture 2626) is provided. The MTF 3002 indicates how the coaxial inspection system 2600 handles different spatial frequencies (e.g., period / mm). For example, the MTF 3002 specifies the response to a periodic sinusoidal pattern (e.g., in the case of spatial frequency 3004) transmitted through the apodized crescent-shaped aperture 2626, as a function of the pattern's spatial frequency (period) and orientation. Figure 30 The MTF distribution of the non-apoptotic circular aperture 3006 (solid line) shown in the figure (e.g., NA = 0.3 at λ = 550 nm) can be compared with the MTF distribution of the apophysically aquifer crescent aperture 2626 (dashed line) (e.g., NA = 0.1 at λ = 550 nm). For example, at resolutions below 20 cycles / mm (e.g., 50 μm), the response of the aquifer crescent aperture 2626 approximates that of the non-apoptotic circular aperture 3006 with a deviation (error) of less than 2%.

[0209] In some embodiments, the aperture stop 2620 may include an electro-optical aperture stop module 2621a. The electro-optical aperture stop module 2621a may be configured to control the transmission of the illumination beam 2614 through the aperture stop 2620. For example, the electro-optical aperture stop module 2621a may include one or more apodization apertures (e.g., apodization quarter-disc aperture 2622, apodization crescent aperture 2626, etc.) capable of rotation and / or translation relative to the optical axis 2612. In some embodiments, the electro-optical aperture stop module 2621a may control the transmission of the illumination beam 2614 in three degrees of freedom. For example, the electro-optical aperture stop module 2621a may control the radial range, angular range, and / or intensity of the illumination beam 2614.

[0210] In some embodiments, aperture stop 2620 may include an optomechanical aperture stop module 2621b. The optomechanical aperture stop module 2621b may be configured to control the transmission of the illumination beam 2614 through aperture stop 2620. For example, the optomechanical aperture stop module 2621b may include multiple aperture stop masks (e.g., apodized quarter-disc aperture stop 2622, apodized crescent-shaped aperture stop 2626, etc.). In some embodiments, the multiple aperture stop masks may be used for different applications and / or measurements (e.g., sequential measurements) of mask plate 2602.

[0211] In some embodiments, adjustments to the illumination beam 2614 and / or the aperture stop 2620 can provide multiple illumination angles to the mask 2602. For example, a first adjustment to the NA of the illumination beam 2614 (e.g., via the electro-optical illumination module 2611) and a second adjustment to the NA of the aperture stop 2620 (e.g., via the electro-optical aperture stop module 2621a) can adjust the yaw (off-axis) illumination angle of the illumination beam 2614 onto the mask 2602.

[0212] In some embodiments, the coaxial inspection system 2600 can operate in a bright field mode. For example, as... Figure 27 As shown, the apodized quarter-disc aperture 2622 can be configured to transmit the central portion of the illumination beam 2614 and provide an angle-insensitive (e.g., angle-free range) off-axis illumination beam 2614 toward the mask 2602. In some embodiments, the coaxial inspection system 2600 is capable of operating in dark field mode. For example, as... Figure 29 As shown, the apodized crescent-shaped aperture 2626 can be configured to block the central portion of the irradiation beam 2614 and provide an angle-sensitive (e.g., having an angular range) off-axis irradiation beam 2614 toward the mask 2602.

[0213] Polarizing beam splitter 2630, focusing lens 2640, and converging lens 2650 can be configured to transmit a selected portion of illumination beam 2614 toward mask 2602 and / or surface 2607 (e.g., via aperture stop 2620) and transmit signal beam 2616 scattered from mask 2602 and / or surface 2607 (e.g., from particles). In some embodiments, polarizing beam splitter 2630, focusing lens 2640, and converging lens 2650 can form an optical system. In some embodiments, polarizing beam splitter 2630 can be a polarizing beam splitter, for example, such as... Figure 31 As shown in the figure. In some embodiments, the focusing lens 2640 and the converging lens 2650 can (e.g., in dark field mode) increase the intensity of the signal beam 2616. For example, the NA of the focusing lens 2640 can be greater than the NA of the converging lens 2650.

[0214] Detector 2660 can be configured to detect signal beam 2616. For example, as Figure 26 As shown, the converging lens 2650 can focus the signal beam 2616 onto the detector 2660. The detector 2660 can be a charge-coupled device (CCD), complementary metal-oxide-semiconductor (CMOS), photodetector, photodiode, and / or any other optoelectronic device capable of detecting the signal beam 2616. The controller 2670 can be configured to provide real-time feedback for image acquisition of the signal beam 2616. For example, as... Figure 26As shown, the controller 2670 can be coupled to the irradiation system 2610, the aperture stop 2620, and / or the detector 2660, for example, to receive the signal beam 2616 and provide control signals to the irradiation system 2610, the aperture stop 2620, and / or the detector 2660 in real time (e.g., less than about 0.1 seconds).

[0215] Figure 31 This is a schematic cross-sectional view of a coaxial inspection system 2600 according to an exemplary embodiment. Figures 26 to 30 The embodiment of the coaxial inspection system 2600 shown is as follows: Figure 31 The embodiment of the coaxial inspection system 2600' shown in the figure can be similar. Similar reference numerals are used to indicate 26 to... Figure 30 Similar features to the embodiment of the coaxial inspection system 2600 shown in the figure, and Figure 31 Similar features to an embodiment of the coaxial inspection system 2600' shown in the figure. Figures 26 to 30 The embodiment of the coaxial inspection system 2600 shown in the figure is similar to... Figure 31 One difference between the embodiment of the coaxial inspection system 2600' shown is that the coaxial inspection system 2600' includes components for polarization optical systems (rather than for...). Figures 26 to 30 The coaxial inspection system 2600 shown in the figure has an unpolarized optical system (e.g., a polarizing beam splitter 2630), a linear polarizer 2632, and a quarter-wave plate 2634.

[0216] like Figure 31An exemplary aspect of the coaxial inspection system 2600' shown is a polarizing beam splitter 2630, a linear polarizer 2632, and a quarter-wave plate 2634 configured to polarize the illumination beam 2614 and block stray light from the detector 2660 by optically isolating (e.g., from particles scattered on the mask 2602) the signal beam 2616. For example, the linear polarizer 2632 can linearly polarize the illumination beam 2614 (e.g., vertically), the polarizing beam splitter 2630 can transmit the linearly polarized illumination beam 2614 (e.g., vertically), the quarter-wave plate 2634 can circularly polarize the linearly polarized illumination beam 2614 (e.g., clockwise), and the circularly polarized illumination beam 2614 (e.g., clockwise) can use a polarization opposite to the original polarization (e.g., counterclockwise) to scatter particles away from the mask 2602 (e.g., the signal beam 2616) and deflect particles. Reflected away from mask 2602, quarter-wave plate 2634 allows unpolarized scattered signal beam 2616 to pass through and converts reflected circularly polarized illumination beam 2614 (e.g., counterclockwise) into linearly polarized reflected illumination beam 2614 (e.g., horizontally), and polarization beam splitter 2630 can transmit unpolarized scattered signal beam 2616 and reject (reflect) linearly polarized reflected illumination beam 2614 (e.g., horizontally) for optical isolation of signal beam 2616 to detector 2660.

[0217] Exemplary Region of Interest (ROI) Inspection System

[0218] Figures 32 to 33C The figure illustrates a ROI inspection system 3200 according to an exemplary embodiment. The ROI inspection system 3200 can be configured to detect ROIs that do not exhibit direct reflection from the illumination pattern on the back side 3204, front side 3206, and / or surface film 3207 of the mask. Although in Figure 32 The ROI inspection system 3200 shown is illustrated as a standalone device and / or system; however, embodiments of this disclosure can be used with other optical systems, such as, but not limited to, lithography devices 100, 100' and / or other optical systems. In some embodiments, the ROI inspection system 3200 may include one or more coaxial inspection systems 2600, 2600'. For example, as... Figure 32 As shown, the ROI inspection system 3200 may include a first (rear) coaxial inspection system 2600, 2600' with a rear detector FOV 3220, and a second (front) coaxial inspection system 2600, 2600' with a front detector FOV 3240.

[0219] like Figure 32As shown, the ROI inspection system 3200 may include a first (rear) coaxial inspection system 2600 with a rear-side detector FOV 3220 and / or a second (front) coaxial inspection system 2600 with a front-side detector FOV 3240 to inspect the mask 3202 and / or the film 3027. For example, the first (rear) coaxial inspection system 2600 may be configured to inspect rear-side particles 3212 on the rear side 3204 of the mask using a first irradiation beam 3210 at the first rear-side ROI 3222. The first irradiation beam 3210 may irradiate the rear-side particles 3212 at the first rear-side ROI 3222 and transmit through the rear side 3204 of the mask to the irradiated pattern 3214, away from the unirradiated pattern 3216, and be reflected back to the rear-side detector FOV 3220 as a direct reflection 3218 (e.g., perpendicular to the rear side 3204 of the mask). Similarly, for example, the second (front-side) coaxial inspection system 2600 can be configured to inspect front-side particles 3232 on the surface film 3207 and / or the front side of the mask 3206 using a second irradiation beam 3230 at the first front-side ROI 3242. The second irradiation beam 3230 can irradiate the front-side particles 3232 at the first front-side ROI 3242 and transmit through the surface film 3207 to the front side of the mask 3206 and the irradiated pattern 3234, far away from the unirradiated pattern 3236, and be reflected back to the front-side detector FOV 3240 as (e.g., perpendicular to the front side of the mask 3206 and the surface film 3207) direct reflection 3238.

[0220] In some embodiments, the rear-side detector FOV 3220 may include one or more ROIs. For example, as Figure 32 As shown, the rear-side detector FOV 3220 may include a first rear-side ROI 3222, a second rear-side ROI 3224, and / or a third rear-side ROI 3226. In some embodiments, the front-side detector FOV 3240 may include one or more ROIs. For example, as... Figure 32 As shown, the front-side detector FOV 3240 may include a first front-side ROI 3242, a second front-side ROI 3224, and / or a third front-side ROI 3246. In some embodiments, the ROI inspection system 3200 may sequentially detect the rear-side detector FOV 3220 and / or the front-side detector FOV 3240. For example, as Figures 33A to 33C As shown, the ROI inspection system 3200 can sequentially inspect and detect the first rear ROI 3222, the second rear ROI 3224, and the third rear ROI 3226, which are respectively used as the first rear image 3310, the second rear image 3320, and the third rear image 3330.

[0221] like Figure 33AAs shown, the ROI inspection system 3200 may include a rear-side coaxial inspection system 2600, which illuminates a first rear-side ROI 3222 in a rear-side detector FOV 3220 to detect a first rear-side image 3310. Figure 33B As shown, the ROI inspection system 3200 may include a rear-side coaxial inspection system 2600, which illuminates a second rear-side ROI 3224 in a rear-side detector FOV 3220 to detect a second rear-side image 3320. Figure 33C As shown, the ROI inspection system 3200 may include a rear-side coaxial inspection system 2600, which illuminates a third rear-side ROI 3226 in a rear-side detector FOV 3220 to detect a third rear-side image 3330. In some embodiments, the first rear-side image 3310, the second rear-side image 3320, and the third rear-side image 3330 may subsequently be reconstructed and stitched together in a digital representation.

[0222] Exemplary AM Inspection System

[0223] Figure 34 The figure illustrates an AM inspection system 3400 according to an exemplary embodiment. The AM inspection system 3400 can be configured to depict stray light that distinguishes from light scattered by particles and to enhance the detection of the signal beam 2616. The AM inspection system 3400 can also be configured to project one or more structured light patterns to detect particle signal, particle depth, and / or ghostlight contribution. Although in Figure 34 The AM inspection system 3400 is shown as a standalone device and / or system, but embodiments of this disclosure can be used with other optical systems, such as, but not limited to, lithography equipment 100, 100', and / or other optical systems. In some embodiments, the AM inspection system 3400 may include one or more coaxial inspection systems 2600, 2600'.

[0224] like Figure 34 As shown, the AM inspection system 3400 may include a coaxial inspection system 2600 having a structured light pattern 2615 to investigate a mask 2602 at different depths (focal planes). In some embodiments, the structured light pattern 2615 may include an AM. For example, the AM may include a spatial frequency (e.g., a resolution of 50 μm) of less than 50 cycles / mm (e.g., less than 20 cycles / mm), such that the response of the aperture stop 2620 can approximate a non-apoptotic circular aperture stop. In some embodiments, the structured light pattern 2615 may include multiple AM ​​patterns. For example, as... Figure 34As shown, the structured light pattern 2615 may include a first AM structured light pattern 2615a (e.g., by I1(x,y) = I DC (x,y) + I A (x,y)cos[ϕ(x,y) + δ1] gives the sinusoidal pattern), the second AM structured light pattern 2615b (e.g., given by I2(x,y) = I DC (x,y) + I A (x,y)cos[ϕ(x,y) + δ2] gives the sinusoidal pattern) and / or the third AM structured light pattern 2615c (e.g., given by I3(x,y) = I DC (x,y) + I A (x,y)cos[ϕ(x,y) + δ3] gives the sine pattern.

[0225] In some embodiments, the AM inspection system 3400 may include three patterns configured to identify particle signal, particle depth, and / or virtual light contributions based on ROI-based image characteristics. For example, as Figure 34 The AM inspection system 3400, shown in the figure, having first, second, and third AM structured light patterns 2615a, 2615b, and 2615c, can respectively investigate the first focal plane 2604a, second focal plane 2604b, and third focal plane 2604c of the back side 2604 of the mask, and respectively detect the first back-side AM image 3402, second back-side AM image 3404, and third back-side AM image 3406 to determine the particle signal (e.g., I). A (x,y)), the particle depth (e.g., ϕ(x,y)), and the virtual light contribution (e.g., I DC (x,y)), because I1(x,y), I2(x,y) and I3(x,y) as well as δ1, δ2 and δ3 are known.

[0226] Exemplary Frequency (FM) Inspection System

[0227] Figure 35 The figure illustrates an FM inspection system 3500 according to an exemplary embodiment. The FM inspection system 3500 can be configured to depict stray light from light scattered by particles and enhance detection of the signal beam 2616. The FM inspection system 3500 can also be configured to project one or more structured light patterns to detect particle signals, particle depth, and / or virtual light contributions. Although in Figure 35The FM inspection system 3500 is shown as a standalone device and / or system, but embodiments of this disclosure can be used with other optical systems, such as, but not limited to, lithography equipment 100, 100', and / or other optical systems. In some embodiments, the FM inspection system 3500 may include one or more coaxial inspection systems 2600, 2600'.

[0228] like Figure 35 As shown, the FM inspection system 3500 may include a coaxial inspection system 2600 with a structured light pattern 2615 to investigate masks 2602 and / or films 2607 at different ROIs. In some embodiments, the structured light pattern 2615 may include FM. For example, FM may include a spatial frequency (e.g., a resolution of 50 μm) of less than 50 cycles / mm (e.g., less than 20 cycles / mm), such that the response of the aperture stop 2620 can approximate a non-apoptotic circular aperture stop. In some embodiments, the structured light pattern 2615 may include multiple FM patterns. For example, as Figure 35 As shown, the structured light pattern 2615 may include a first FM structured light pattern 2615a (e.g., derived from I1(x,y; t) = I DC (x,y) + I A (x,y)cos[2πf(x,y)t + δ1(x,y)] gives the sinusoidal pattern), the second FM structured light pattern 2615b (e.g., given by I2(x,y; t) = I DC (x,y) + I A (x,y)cos[2πf(x,y)t + δ2(x,y)] gives the sinusoidal pattern) and / or the third FM structured light pattern 2615c (e.g., given by I3(x,y; t) = I DC (x,y) + I A (x,y)cos[2πf(x,y)t + δ3(x,y)] gives the sine pattern.

[0229] In some embodiments, the FM inspection system 3500 may include three patterns configured to identify particle signals, particle depth, and / or virtual light contributions based on Fourier transform characteristics. For example, as Figure 35 The FM inspection system 3500, shown in the figure, having first, second, and third FM structured light patterns 2615a, 2615b, and 2615c, can respectively investigate the first ROI (e.g., A) of the film 2607. 1 ), second ROI (e.g., B) 1 ) and third ROI (e.g., C 1), and respectively detect the first front-side FM curve 3502, the second front-side FM curve 3504, and the third front-side FM curve 3506 to eliminate the first virtual reflection 3510 and the second virtual reflection 3520, and determine the particle signal (e.g., I A (x,y)), the particle depth (e.g., f(x,y)), and the virtual light contribution (e.g., I DC (x,y)), because I1(x,y; t), I2(x,y; t) and I3(x,y; t) and δ1(x,y), δ2(x,y) and δ3(x,y) are known.

[0230] Exemplary inspection array system

[0231] Figure 36 The figure illustrates an inspection array system 3600 according to an exemplary embodiment. The inspection array system 3600 can be configured to provide simultaneous measurement of multiple ROIs on the rear side 2604 of the mask, the front side 2606 of the mask, and / or the surface film 2607. Although in Figure 36 The inspection array system 3600 is shown as a separate device and / or system, but embodiments of this disclosure can be used in other optical systems, such as, but not limited to, lithography devices 100, 100', and / or other optical systems.

[0232] like Figure 36 As shown, the inspection array system 3600 may include one or more coaxial inspection systems 2600, 2600'. For example, as Figure 36 As shown, the inspection array system 3600 may include a first (rear) coaxial inspection system 2600, 2600' adjacent to the second (rear) coaxial inspection systems 2600, 2600', and a first (front) coaxial inspection system 2600, 2600' adjacent to the second (front) coaxial inspection systems 2600, 2600', wherein the first and second (rear) coaxial inspection systems 2600, 2600' are opposite to the first and second (front) coaxial inspection systems 2600, 2600'. In some embodiments, measurement results from the array of coaxial inspection systems 2600, 2600' can be acquired simultaneously. For example, the measurements can be performed simultaneously in real time. In some embodiments, measurement results from the array of coaxial inspection systems 2600, 2600' can be acquired sequentially. For example, the measurement results can then be reconstructed and stitched together in a digital representation.

[0233] Other aspects of the invention are set forth in the following numbered aspects.

[0234] 1. An inspection system, comprising:

[0235] A radiation source, the radiation source being configured to generate a radiation beam and being configured to:

[0236] The beam irradiates a first surface of an object, wherein a first parameter of the beam defines a region of the first surface of the object.

[0237] The second surface of the object is irradiated, and a second parameter of the beam defines a region of the second surface, wherein the second surface is located at a different depth level within the object than the first surface;

[0238] The detector is configured to:

[0239] The field of view (FOV) defining the area of ​​the first surface including the first surface, and

[0240] Receive radiation scattered from the region of the first surface and the region of the second surface; and

[0241] Processing circuitry system, the processing circuitry system being configured to:

[0242] Discard image data that was not received from the area of ​​the first surface, and

[0243] Construct a synthetic image, the synthetic image comprising image data from the entire region covering the first surface.

[0244] 2. The inspection system according to aspect 1, wherein the area of ​​the first surface and the area of ​​the second surface do not overlap within the FOV.

[0245] 3. The inspection system according to aspect 1, wherein:

[0246] The radiation source is also configured to generate a second radiation beam and irradiate the first surface of the object, the second beam defining another area of ​​the first surface located within the FOV;

[0247] The detector is also configured to receive radiation scattered from the other region of the first surface and at least one other region of the second surface, wherein the other region of the first surface and the at least one other region of the second surface do not overlap in the field of view (FOV); and

[0248] The processing circuit system is also configured to:

[0249] Discard image data that was not received from the other area of ​​the first surface, and

[0250] The synthesized image is constructed to include image data from the entire region covering the first surface and from the entire other region covering the first surface.

[0251] 4. The inspection system according to aspect 3, wherein the processing circuitry is further configured to determine whether a particle is located within the FOV based on the synthesized image.

[0252] 5. The inspection system according to aspect 3, wherein the shape of the region of the first surface is independent of the shape of the other region of the first surface.

[0253] 6. The inspection system according to aspect 1, wherein the shape of the region of the second surface corresponds to the shape of the region of the first surface.

[0254] 7. The inspection system according to aspect 1, wherein:

[0255] The second surface includes another region located below the region of the first surface, having a size corresponding to the region of the first surface, and

[0256] When the area of ​​the first surface is irradiated, the other area of ​​the second surface is not irradiated.

[0257] 8. The inspection system according to aspect 1, wherein:

[0258] The width of the beam is defined by a first illumination cone and a second illumination cone, the first and second illumination cones comprising two marginal rays and one main ray.

[0259] The width of the region on the first surface is defined by a first observation light cone and a second observation light cone, the first and second observation light cones comprising two edge rays and a main ray.

[0260] The principal ray of the irradiating light cone and the principal ray of the observing light cone intersect at the first surface of the object, and

[0261] The edge rays of the irradiating light cone and the edge rays of the observing light cone do not intersect at the second surface of the object.

[0262] 9. The inspection system according to aspect 1 further includes an optical modulation element configured to determine the position and coordinates of the region of the first surface within the FOV.

[0263] 10. The inspection system according to aspect 1, wherein the region of the second surface includes a diffraction pattern.

[0264] 11. An inspection method, comprising:

[0265] A first surface of an object is irradiated using a radiation source that generates a radiation beam, wherein a first parameter of the beam defines a region of the first surface of the object.

[0266] The second surface of the object is irradiated, and a second parameter of the beam defines a region of the second surface, wherein the second surface is located at a different depth level within the object than the first surface;

[0267] The field of view (FOV) of the region including the first surface is defined by the first surface.

[0268] Receive radiation scattered from the region of the first surface and the region of the second surface;

[0269] Discard image data that was not received from the area of ​​the first surface; and

[0270] Construct a synthetic image, the synthetic image comprising image data from the entire region covering the first surface.

[0271] 12. The inspection method according to aspect 11, wherein the area of ​​the first surface and the area of ​​the second surface do not overlap within the FOV.

[0272] 13. The inspection method according to aspect 11 further includes:

[0273] The first surface of the object is irradiated with a second radiation beam, the second beam defining another area of ​​the first surface located within the field of view (FOV);

[0274] Receive radiation scattered from the other region of the first surface and at least one other region of the second surface, wherein the other region of the first surface and the at least one other region of the second surface do not overlap in the field of view (FOV);

[0275] Discard image data that was not received from the other area of ​​the first surface;

[0276] The synthesized image is constructed to include image data from the entire region covering the first surface and from the entire other region covering the first surface.

[0277] 14. The inspection method according to aspect 13 further includes: determining whether a particle is located within the FOV based on the synthesized image.

[0278] 15. The inspection method according to aspect 13, wherein the shape of the region of the first surface is independent of the shape of the other region of the first surface.

[0279] 16. The inspection method according to aspect 11, wherein the shape of the region of the second surface corresponds to the shape of the region of the first surface.

[0280] 17. The inspection method according to aspect 11, wherein:

[0281] The second surface includes another region located below the region of the first surface, having a size corresponding to the region of the first surface, and

[0282] The method further includes:

[0283] When the area of ​​the first surface is irradiated, the other area of ​​the second surface is not irradiated.

[0284] 18. The inspection method according to aspect 11 further includes:

[0285] The width of the beam is defined by a first irradiation cone and a second irradiation cone, the first irradiation cone and the second irradiation cone comprising two edge rays and one main ray;

[0286] The width of the region on the first surface is defined by a first observation light cone and a second observation light cone, the first and second observation light cones comprising two edge rays and a main ray, wherein:

[0287] The principal ray of the irradiating light cone and the principal ray of the observing light cone intersect at the first surface of the object, and

[0288] The edge rays of the irradiating light cone and the edge rays of the observing light cone do not intersect at the second surface of the object.

[0289] 19. The inspection method according to aspect 1 further includes: using an optical modulation element to select the position and coordinates of the region of the first surface within the FOV.

[0290] 20. A photolithography apparatus, comprising:

[0291] Inspection system, the inspection system comprising:

[0292] A radiation source, the radiation source being configured to generate a radiation beam and being configured to:

[0293] The beam irradiates a first surface of an object, wherein a first parameter of the beam defines a region of the first surface of the object.

[0294] The second surface of the object is irradiated, and a second parameter of the beam defines a region of the second surface, wherein the second surface is located at a different depth level within the object than the first surface;

[0295] The detector is configured to:

[0296] The field of view (FOV) defining the area of ​​the first surface including the first surface, and

[0297] Receive radiation scattered from the region of the first surface and the region of the second surface; and

[0298] Processing circuitry system, the processing circuitry system being configured to:

[0299] Discard image data that was not received from the area of ​​the first surface, and

[0300] Construct a synthetic image, the synthetic image comprising image data from the entire region covering the first surface.

[0301] 21. A system comprising:

[0302] An irradiation system configured to transmit an irradiation beam along an irradiation path;

[0303] An aperture stop, the aperture stop being configured to select a portion of the illumination beam;

[0304] An optical system configured to transmit a selected portion of the illumination beam toward a mask and to transmit a signal beam scattered from the mask; and

[0305] Detector, the detector being configured to detect the signal beam,

[0306] The illumination system, the aperture stop, the optical system, and the detector are optically coaxial.

[0307] 22. The system according to aspect 21, wherein the aperture stop includes an apodization aperture stop.

[0308] 23. The system according to aspect 22, wherein the apogeometry aperture includes a quarter-disc aperture or a crescent-shaped aperture.

[0309] 24. The system according to aspect 21, wherein, in bright field mode, the aperture stop includes an apodized quarter-disc aperture stop configured to transmit a central portion of the illumination beam and provide an angle-insensitive off-axis illumination beam toward the mask.

[0310] 25. The system according to aspect 21, wherein, in dark field mode, the aperture stop includes an apodized crescent-shaped aperture stop configured to block a central portion of the illumination beam and provide an angle-sensitive off-axis illumination beam toward the mask.

[0311] 26. The system according to aspect 25, wherein the numerical aperture of the focusing lens of the optical system is larger than the numerical aperture of the converging lens of the optical system in order to increase the intensity of the signal beam.

[0312] 27. The system according to aspect 21, wherein the aperture stop includes an electro-optical aperture stop module configured to control the transmission of the illumination beam through the aperture stop.

[0313] 28. The system according to aspect 27, wherein the electro-optic aperture module controls the transmission of the illumination beam in three degrees of freedom.

[0314] 29. The system according to aspect 28, wherein the three degrees of freedom include radial range, angular range, and intensity.

[0315] 30. The system according to aspect 21, wherein the aperture stop includes an optomechanical aperture stop module configured to control the transmission of the illumination beam through the aperture stop.

[0316] 31. The system according to aspect 30, wherein the optomechanical aperture module includes a plurality of aperture masks.

[0317] 32. The system according to aspect 21, wherein the irradiation system includes an electro-optical irradiation module configured to electronically control the irradiation beam.

[0318] 33. The system according to aspect 32, wherein the electro-optical illumination module includes a digital micromirror device (DMD), a liquid crystal modulator (LCM), a spatial light modulator (SLM), and / or some combination thereof.

[0319] 34. The system according to aspect 32, wherein the electro-optical irradiation module controls the numerical aperture of the irradiation beam.

[0320] 35. The system according to aspect 21, wherein a first adjustment to the numerical aperture of the irradiation beam and a second adjustment to the aperture stop provide multiple irradiation angles for the mask.

[0321] 36. The system according to aspect 21 further includes a controller coupled to the irradiation system, the aperture stop, and / or the detector, the controller being configured to provide real-time feedback on image acquisition of the signal beam.

[0322] 37. The system according to aspect 21, wherein:

[0323] The optical system includes a linear polarizer, a polarization beam splitter, and a quarter-wave plate.

[0324] The optical system is configured to block stray radiation from the signal beam.

[0325] 38. The system according to aspect 21, wherein the optical system includes a focusing lens, a beam splitter, and a converging lens.

[0326] 39. The system according to aspect 38, wherein the numerical aperture of the focusing lens is larger than the numerical aperture of the converging lens in order to increase the intensity of the signal beam.

[0327] 40. The system according to aspect 21, wherein the illumination beam comprises a structured light pattern.

[0328] 41. The system according to aspect 21, wherein the irradiation beam comprises a plurality of narrow spectral bands.

[0329] 42. A system comprising:

[0330] An illumination system configured to transmit an illumination beam along an illumination path, wherein the illumination beam includes a structured light pattern.

[0331] An aperture stop, the aperture stop being configured to select a portion of the illumination beam, wherein the aperture stop includes an apodization aperture stop;

[0332] An optical system configured to transmit a selected portion of the illumination beam toward a target and to transmit a signal beam scattered from the target; and

[0333] A detector configured to detect the signal beam.

[0334] 43. The system according to aspect 42, wherein the structured light pattern includes amplitude modulation (AM).

[0335] 44. The system according to aspect 43, wherein the AM includes a spatial frequency of less than 50 cycles / mm.

[0336] 45. The system according to aspect 43, wherein the AM comprises three patterns configured to identify the particle signal, particle depth, and / or the virtual light contribution of the target based on image characteristics of each region of interest.

[0337] 46. ​​The system according to aspect 42, wherein the structured light pattern includes frequency modulation (FM).

[0338] 47. The system according to aspect 46, wherein the FM comprises a spatial frequency of less than 50 cycles / mm.

[0339] 48. The system according to aspect 46, wherein the FM comprises three patterns configured to identify the particle signal, particle depth, and / or the virtual light contribution of the target based on the Fourier transform characteristics of each region of interest.

[0340] 49. The system according to aspect 42, wherein the illumination system, the aperture stop, the optical system, and the detector are aligned along the optical axis.

[0341] 50. An apparatus comprising:

[0342] An irradiation system configured as an irradiation pattern forming apparatus;

[0343] A projection system configured to project an image of the pattern forming apparatus onto a substrate; and

[0344] An inspection system for detecting particles on the pattern forming apparatus, the inspection system comprising:

[0345] A second irradiation system, configured to transmit an irradiation beam along an irradiation path;

[0346] An aperture stop, the aperture stop being configured to select a portion of the illumination beam;

[0347] An optical system configured to transmit the selected portion of the illumination beam toward the pattern forming apparatus and to transmit a signal beam scattered from the pattern forming apparatus; and

[0348] Detector, the detector being configured to detect the signal beam,

[0349] The second illumination system, the aperture stop, the optical system, and the detector are aligned along the optical axis.

[0350] 51. The apparatus according to aspect 50, wherein, in bright field mode, the aperture stop includes an apodized quarter-disc aperture stop configured to transmit a central portion of the irradiation beam and provide an angle-insensitive off-axis irradiation beam toward the pattern forming apparatus.

[0351] 52. The apparatus according to aspect 50, wherein, in dark field mode, the aperture stop includes an apodized crescent-shaped aperture stop configured to block a central portion of the irradiation beam and provide an angle-sensitive off-axis irradiation beam toward the pattern forming apparatus.

[0352] 53. The apparatus according to aspect 50 further includes a second inspection system arranged opposite to the inspection system.

[0353] 54. The apparatus according to aspect 50 further includes a second inspection system arranged adjacent to the inspection system.

[0354] While the use of lithography equipment in IC manufacturing may be specifically mentioned herein, it should be understood that the lithography equipment described herein may have other applications, such as manufacturing integrated optical systems, guiding and detecting patterns for magnetic domain memory, flat panel displays, LCDs, thin-film magnetic heads, etc. Those skilled in the art will understand that in the context of such alternative applications, any terms “wafer” or “die” used herein may be considered synonymous with the more general terms “substrate” or “target portion,” respectively. Substrates mentioned herein may be processed before or after exposure, for example in a track unit or coating and developing system unit (a tool typically used to apply a resist layer to a substrate and develop the exposed resist), a measurement unit, and / or an inspection unit. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Furthermore, the substrate may be processed more than once, for example for producing multilayer ICs, such that the term “substrate” used herein may also refer to a substrate that already contains multiple processed layers.

[0355] While the use of embodiments of this disclosure in the context of optical lithography has been specifically mentioned above, it will be understood that this disclosure can be used in other applications, such as imprint lithography, and is not limited to optical lithography where circumstances permit. In imprint lithography, the morphology in the patterning apparatus defines a pattern formed on a substrate. The morphology of the patterning apparatus can be imprinted into a resist layer supplied to the substrate, whereby the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist is cured, the patterning apparatus is removed from the resist, thereby leaving a pattern therein.

[0356] It should be understood that the wording or terminology used herein is for descriptive rather than restrictive purposes, and that the terminology or terminology used herein shall be interpreted by those skilled in the art in accordance with the teachings herein.

[0357] In the embodiments described herein, the terms "lens" and "lens element" may refer to any one or a combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components, where the context permits.

[0358] Additionally, the terms “radiation” and “beam” and “light” used herein can encompass all types of electromagnetic radiation, such as ultraviolet (UV) radiation (e.g., wavelengths λ of 365 nm, 355 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and extreme ultraviolet (EUV or soft X-ray) radiation (e.g., wavelengths in the range of 5 nm to 20 nm, such as, for example, 13.5 nm), or hard X-rays operating at wavelengths less than 5 nm, as well as particle beams (such as ion beams or electron beams). Generally, radiation with wavelengths between approximately 400 nm and approximately 700 nm is considered visible light radiation; radiation with wavelengths between approximately 780 nm and 3000 nm (or greater) is considered IR radiation. UV refers to radiation with wavelengths between approximately 100 nm and 400 nm. In photolithography, the term “UV” also applies to wavelengths that can be produced by a mercury discharge lamp: G line 436 nm; H line 405 nm; and / or I line 365 nm. Vacuum UV or VUV (i.e., UV absorbed by a gas) refers to radiation with a wavelength of approximately 100-200 nm. Deep UV (DUV) generally refers to radiation with a wavelength range from 126 nm to 428 nm, and in some embodiments, excimer lasers can generate DUV radiation used within lithography equipment. It should be understood that radiation with wavelengths in, for example, the 5-20 nm range refers to radiation having at least partially within a wavelength band of the 5-20 nm range.

[0359] As used herein, the term "substrate" can describe the material on which the various material layers are added. In some embodiments, the substrate itself may be patterned, and the material added on top of it may also be patterned, or may remain unpatterned.

[0360] While specific references may be made herein to the use of devices and / or systems according to this disclosure in the manufacture of ICs, it should be clearly understood that such devices and / or systems may have many other possible applications. For example, such devices and / or systems may be used to manufacture integrated optical systems, guide and detect patterns for magnetic domain memories, LCD panels, thin-film magnetic heads, etc. Those skilled in the art will understand that in the context of such alternative applications, any use of the terms "patterning apparatus," "mask," "wafer," or "die" should be replaced by the more general terms "mask," "substrate," and "target portion," respectively.

[0361] While specific embodiments of this disclosure have been described above, it will be understood that this disclosure can be practiced in ways other than those described. The description is not intended to limit this disclosure.

[0362] It will be understood that the Detailed Description section, rather than the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may illustrate one or more exemplary embodiments of this disclosure as contemplated by the inventors, but not all exemplary embodiments, and are therefore not intended to limit this disclosure and the appended claims in any way.

[0363] The present disclosure has been described above with the aid of functional building blocks that illustrate the implementation of the specified functions and their interrelationships. For ease of description, the boundaries of these functional building blocks have been arbitrarily defined herein. Alternative boundaries can be defined as long as the specified functions and their relationships are properly performed.

[0364] The foregoing description of the specific embodiments so fully reveals the general nature of this disclosure that, without departing from the overall concept of this disclosure and without excessive experimentation, others can readily modify and / or adapt various applications of these specific embodiments by applying knowledge within the scope of the art. Therefore, based on the teachings and guidance set forth herein, such adaptations and modifications are intended to fall within the meaning and scope of equivalents of the disclosed embodiments.

[0365] The breadth and scope of this disclosure should not be limited by any of the exemplary embodiments described above, but should be defined only by the appended claims and their equivalents.

Claims

1. An inspection system, comprising: A radiation source, the radiation source being configured to generate a radiation beam and being configured to: The beam irradiates a first surface of an object, wherein a first parameter of the beam defines a region of the first surface of the object. The second surface of the object is irradiated, and a second parameter of the beam defines a region of the second surface, wherein the second surface is located at a different depth level within the object than the first surface; The detector is configured to: The field of view defining the area of ​​the first surface, and Receive radiation scattered from the region of the first surface and the region of the second surface; as well as Processing circuitry system, the processing circuitry system being configured to: Discard image data that was not received from the area of ​​the first surface, and Construct a synthetic image, the synthetic image comprising image data from the entire region covering the first surface.

2. The inspection system according to claim 1, wherein, The regions of the first surface and the regions of the second surface do not overlap within the field of view.

3. The inspection system according to claim 1, wherein: The radiation source is also configured to generate a second radiation beam and irradiate the first surface of the object, the second radiation beam defining another area of ​​the first surface within the field of view; The detector is also configured to receive radiation scattered from the other region of the first surface and at least one other region of the second surface, wherein the other region of the first surface and the at least one other region of the second surface do not overlap in the field of view; and The processing circuit system is also configured to: Discard image data that was not received from the other area of ​​the first surface, and The synthesized image is constructed to include image data from the entire region covering the first surface and from the entire other region covering the first surface.

4. The inspection system according to claim 3, wherein, The processing circuitry is also configured to determine whether a particle is located within the field of view based on the synthesized image.

5. The inspection system according to claim 3, wherein, The shape of the region on the first surface is independent of the shape of the other region on the first surface.

6. The inspection system according to claim 1, wherein, The shape of the region on the second surface corresponds to the shape of the region on the first surface.

7. The inspection system according to claim 1, wherein: The second surface includes another region located below the region of the first surface, having a size corresponding to the region of the first surface, and When the area of ​​the first surface is irradiated, the other area of ​​the second surface is not irradiated.

8. The inspection system according to claim 1, wherein: The width of the beam is defined by a first illumination cone and a second illumination cone, the first and second illumination cones comprising two marginal rays and one main ray. The width of the region on the first surface is defined by a first observation light cone and a second observation light cone, the first and second observation light cones comprising two edge rays and a main ray. The principal ray of the irradiating light cone and the principal ray of the observing light cone intersect at the first surface of the object, and The edge rays of the irradiating light cone and the edge rays of the observing light cone do not intersect at the second surface of the object.

9. The inspection system of claim 1 further includes an optical modulation element configured to determine the position and coordinates of the region of the first surface within the field of view.

10. The inspection system according to claim 1, wherein, The region on the second surface includes a diffraction pattern.

11. An inspection method, comprising: A first surface of an object is irradiated using a radiation source that generates a radiation beam, wherein a first parameter of the beam defines a region of the first surface of the object. The second surface of the object is irradiated, and a second parameter of the beam defines a region of the second surface, wherein the second surface is located at a different depth level within the object than the first surface; The field of view that defines the area of ​​the first surface; Receive radiation scattered from the region of the first surface and the region of the second surface; Discard image data that was not received from the area of ​​the first surface; as well as Construct a synthetic image, the synthetic image comprising image data from the entire region covering the first surface.

12. The inspection method according to claim 11, wherein, The regions of the first surface and the regions of the second surface do not overlap within the field of view.

13. The inspection method according to claim 11, further comprising: The first surface of the object is irradiated with a second radiation beam, the second radiation beam defining another area of ​​the first surface located within the field of view; Receive radiation scattered from the other region of the first surface and at least one other region of the second surface, wherein the other region of the first surface and the at least one other region of the second surface do not overlap in the field of view; Discard image data that was not received from the other area of ​​the first surface; The synthesized image is constructed to include image data from the entire region covering the first surface and from the entire other region covering the first surface.

14. The inspection method according to claim 13, further comprising: The location of the particle within the field of view is determined based on the synthesized image.

15. The inspection method according to claim 13, wherein, The shape of the region on the first surface is independent of the shape of the other region on the first surface.

16. The inspection method according to claim 11, wherein, The shape of the region on the second surface corresponds to the shape of the region on the first surface.

17. The inspection method according to claim 11, wherein: The second surface includes another region located below the region of the first surface, having a size corresponding to the region of the first surface, and The method further includes: When the area of ​​the first surface is irradiated, the other area of ​​the second surface is not irradiated.

18. The inspection method according to claim 11, further comprising: The width of the beam is defined by a first irradiation cone and a second irradiation cone, the first irradiation cone and the second irradiation cone comprising two edge rays and one main ray; The width of the region on the first surface is defined by a first observation light cone and a second observation light cone, the first and second observation light cones comprising two edge rays and a main ray, wherein: The principal ray of the irradiating light cone and the principal ray of the observing light cone intersect at the first surface of the object, and The edge rays of the irradiating light cone and the edge rays of the observing light cone do not intersect at the second surface of the object.

19. The inspection method according to claim 11, further comprising: A light modulation element is used to select the position and coordinates of the region of the first surface within the field of view.

20. A photolithography apparatus, comprising: Inspection system, the inspection system comprising: A radiation source, the radiation source being configured to generate a radiation beam and being configured to: The beam irradiates a first surface of an object, wherein a first parameter of the beam defines a region of the first surface of the object. The second surface of the object is irradiated, and a second parameter of the beam defines a region of the second surface, wherein the second surface is located at a different depth level within the object than the first surface; The detector is configured to: The field of view defining the area of ​​the first surface, and Receive radiation scattered from the region of the first surface and the region of the second surface; and Processing circuitry system, the processing circuitry system being configured to: Discard image data that was not received from the area of ​​the first surface, and Construct a synthetic image, the synthetic image comprising image data from the entire region covering the first surface.

Images