System and method for inspecting parts of a lithographic apparatus - Patents.com

Abstract

The described system comprises an inspection system and associated software. The inspection system comprises a body configured to be inserted into a lithographic apparatus, engaged by a tool handler of the lithographic apparatus, and used to inspect a portion of the lithographic apparatus. A camera is coupled to the body and configured to acquire images of the portion of the lithographic apparatus as the tool handler positions the body. The software is configured to receive the images and assist in semi-automated or automated inspection of the portion of the lithographic apparatus based on the one or more images. Compared to conventional approaches, the described system requires little inspection time, produces consistent image resolution and image sharpness, does not require opening or otherwise disassembling the lithographic apparatus, reduces impact and potential contamination of the microenvironment of the lithographic apparatus, and has other advantages.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority to U.S. Application No. 63 / 301,511, filed January 21, 2022, which is incorporated by reference in its entirety.

[0002] [Technical field] The present disclosure relates generally to systems and methods for inspecting parts of a lithographic apparatus. [Background technology]

[0003] Lithographic (e.g. projection) apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device (e.g. mask) may contain or provide a pattern corresponding to an individual layer of the IC (the "design layout"), which can be transferred onto a target portion (e.g. comprising one or more dies) on a substrate (e.g. a silicon wafer) that is coated with a layer of radiation-sensitive material ("resist"), such as by irradiating the target portion through the patterning device. Typically, a single substrate will contain several adjacent target portions, and the pattern is transferred successively by the lithographic projection apparatus, one target portion at a time. In one type of lithographic projection apparatus, the pattern of the entire patterning device is transferred onto one target portion in one go. Such an apparatus is commonly referred to as a stepper. Other apparatus, commonly referred to as step-and-scan apparatus, simultaneously move the substrate parallel or anti-parallel to a predetermined reference direction (the "scan" direction) while the projection beam scans over the patterning device in this reference direction. Different portions of the pattern on the patterning device are sequentially transferred to one target portion. Typically, a lithographic projection apparatus will have a demagnification ratio M (e.g. 4), so that the speed F at which the substrate moves will be 1 / M times the speed at which the projection beam scans the patterning device. Further information on the lithographic apparatus described herein can be taken from, for example, US 6,046,792, which is incorporated herein by reference. Summary of the Invention

[0004] An inspection system and associated software are described. The inspection system comprises a body configured to be inserted into a lithographic apparatus, engaged by a tool handler of the lithographic apparatus, and used to inspect a portion of the lithographic apparatus. A camera is coupled to the body and configured to acquire images of the portion of the lithographic apparatus as the tool handler positions the body. Software is configured to receive the images and assist in semi-automated or automated inspection of the portion of the lithographic apparatus based on the one or more images. Compared to conventional approaches, the described system requires little inspection time, produces consistent image resolution and image sharpness, does not require opening or otherwise disassembling the lithographic apparatus, reduces impact on the microenvironment of the lithographic apparatus, reduces potential contamination during inspection, and has other advantages.

[0005] According to an embodiment, there is provided a system for inspecting a portion of a lithographic apparatus, the system comprising a body configured to be inserted into the lithographic apparatus and engaged by a tool handler of the lithographic apparatus and positioned by the tool handler to inspect the portion of the lithographic apparatus, the system comprising one or more image acquisition devices coupled to the body, the one or more image acquisition devices configured to acquire one or more images of the portion of the lithographic apparatus in response to the tool handler positioning the body.

[0006] In some embodiments, the body has a similar or identical shape to a reticle that is to be engaged and positioned by the tool handler. In some embodiments, the body is rectangular. The tool handler comprises a reticle handler and a turret gripper. The reticle handler is configured to move the body from a load port of the lithographic apparatus to the turret gripper, the turret gripper configured to grip the body at one or more edges and / or surfaces of the body, move the body to a position adjacent to a portion of the lithographic apparatus, and adjust the position of the body.

[0007] In some embodiments, the portion of the lithographic apparatus comprises one or more membrane surfaces of the lithographic apparatus, hi some embodiments, the portion of the lithographic apparatus comprises a chuck membrane associated with a reticle stage reticle clamp.

[0008] In some embodiments, the one or more image capture devices comprise one or more optical cameras. In some embodiments, the system comprises one or more light sources associated with the one or more image capture devices and coupled to the body. The one or more light sources are configured to illuminate a portion of the lithographic apparatus imaged by the one or more image capture devices. In some embodiments, the one or more light sources comprise one or more light emitting diodes (LEDs).

[0009] In some embodiments, the system includes electronics coupled to the body configured to receive and store one or more images from the one or more image capture devices and / or wirelessly communicate information to and from the one or more image capture devices.

[0010] In some embodiments, the system includes a power supply coupled to the body, the power supply configured to provide power to the one or more image capture devices, the one or more light sources, and / or associated electronics.

[0011] In some embodiments, the body comprises one or more identification features, which may comprise one or more of a label, a bar code, and an alignment mark.

[0012] In some embodiments, the system comprises one or more processors configured with machine readable instructions to receive one or more images from the one or more image acquisition devices, facilitate semi-automated or automated inspection of portions of the lithographic apparatus based on the one or more images, and communicate data to one or more external computing devices.

[0013] In some embodiments, the one or more processors are configured to facilitate semi-automated inspection. Facilitating the semi-automated inspection comprises displaying one or more images to a user using a user interface and receiving input and / or selection of control commands from the user via the user interface. The control commands comprise instructions to move the body and the one or more image acquisition devices based on a region of interest of the portion of the lithographic apparatus, instructions to adjust a focus of the one or more image acquisition devices, instructions to adjust illumination from one or more light sources associated with the one or more image acquisition devices, and / or instructions to acquire an updated image using the adjusted focus and / or illumination. The one or more processors are configured to display the updated image to the user using the user interface, such that the user can determine the presence of contamination in the region of interest based on the updated image. In some embodiments, displaying the one or more images and / or the updated image to the user comprises a live stream.

[0014] In some embodiments, the one or more processors are configured to facilitate automated inspection comprising determining a region of interest of a portion of the lithographic apparatus based on the one or more images, controlling the tool handler to move the body and the one or more image acquisition devices based on the region of interest, adjusting a focus of the one or more image acquisition devices based on the one or more images, adjusting illumination from one or more light sources associated with the one or more image acquisition devices based on the one or more images, causing the one or more image acquisition devices to acquire updated images using the adjusted focus and / or illumination, and / or determining a presence of contamination in the region of interest based on the updated images.

[0015] In some embodiments, the one or more processors are configured to facilitate automated inspection based on a trained machine learning algorithm configured to receive one or more images as input and output corresponding control commands related to determining an area of ​​interest, controlling the tool handler to move the body and the one or more image capture devices, adjusting focus, adjusting lighting, causing the one or more image capture devices to capture updated images, and / or determining the presence of contamination.

[0016] In some embodiments, the trained machine learning algorithm is trained based on previously acquired images of portions of the lithographic apparatus with or without contamination. The previously acquired images are labeled with an area of ​​interest, the location of the body and / or imaging device relative to the area of ​​interest, imaging device focus, illumination, and / or an indication of whether contamination is present. The performance of the lithographic apparatus is related to the contamination identified in the images, and correlations between the lithographic apparatus performance data and the image inspection data are used to configure the machine learning algorithm.

[0017] In some embodiments, the trained machine learning algorithm comprises a neural network having an input layer, an output layer, and one or more hidden layers.

[0018] In some embodiments, the lithographic apparatus is configured for deep ultraviolet (DUV) radiation or extreme ultraviolet (EUV) radiation.

[0019] According to another embodiment, a computer program product is provided comprising a non-transitory computer readable medium having instructions recorded thereon. The instructions, when executed by one or more processors of a computer, cause an operation comprising receiving one or more images from one or more image acquisition devices included in an inspection system for inspecting a portion of a lithographic apparatus. The system comprises a body configured to be inserted into the lithographic apparatus and engaged by a tool handler of the lithographic apparatus and positioned by the tool handler to inspect the portion of the lithographic apparatus. The system comprises one or more image acquisition devices. The one or more image acquisition devices are coupled to the body. The one or more image acquisition devices are configured to acquire one or more images of the portion of the lithographic apparatus in response to the tool handler positioning the body. The operation further comprises facilitating inspection of the portion of the lithographic apparatus based on the one or more images. In some embodiments, the one or more processors are configured to facilitate automatic or semi-automatic inspection.

[0020] According to another embodiment, there is provided a method of inspecting a portion of a lithographic apparatus. The method comprises receiving a body for insertion into the lithographic apparatus. The body is configured to be engaged by a tool handler of the lithographic apparatus and positioned by the tool handler to inspect the portion of the lithographic apparatus. The method comprises acquiring one or more images of the portion of the lithographic apparatus using one or more image acquisition devices coupled to the body. The one or more image acquisition devices are configured to acquire one or more images of the portion of the lithographic apparatus in response to the tool handler positioning the body. In some embodiments, the method comprises receiving one or more images from the one or more image acquisition devices using one or more processors, facilitating a semi-automated or automated inspection of the portion of the lithographic apparatus based on the one or more images using the one or more processors, and communicating data to one or more external computing devices using the one or more processors. [Brief description of the drawings]

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments and, together with the description, explain these embodiments. Embodiments of the invention are described, by way of example only, with reference to the following accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts:

[0022] [Figure 1] 1 depicts a schematic diagram of a lithographic apparatus according to an embodiment;

[0023] [Diagram 2] FIG. 2 illustrates a schematic diagram of an embodiment of a lithographic cell or cluster according to an embodiment.

[0024] [Figure 3A] FIG. 1 illustrates a schematic diagram of a lithographic apparatus including a reticle handler turret gripper, a reticle stage reticle clamp, and / or other components according to an embodiment.

[0025] [Figure 3B] FIG. 3B illustrates an enlarged view of a portion of the lithographic apparatus shown in FIG. 3A according to an embodiment.

[0026] [Figure 4] FIG. 1 is a schematic diagram illustrating an inspection system according to an embodiment.

[0027] [Diagram 5] FIG. 1 is a diagram illustrating an inspection flow according to an embodiment.

[0028] [Figure 6] FIG. 2 is a schematic diagram of a reticle handler turret gripper gripping an inspection system according to an embodiment;

[0029] [Figure 7] 2 is a side view diagram that illustrates a schematic of a foot of a reticle handler turret gripper gripping an inspection system according to one embodiment. FIG.

[0030] [Figure 8] 1A-1C are schematic top views of a reticle stage, reticle clamps, and / or associated membranes according to one embodiment;

[0031] [Figure 9] 2 illustrates a turret gripper and turret gripper feet as viewed through (upward) an inspection system according to one embodiment. FIG.

[0032] [Figure 10] 1 illustrates a method for inspecting a part of a lithographic apparatus according to an embodiment;

[0033] [Figure 11] FIG. 1 is a block diagram illustrating an example of a computer system according to an embodiment.

[0034] [Figure 12] FIG. 2 depicts a schematic diagram of a lithographic projection apparatus similar to that of FIG. 1 according to an embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] In general, a mask or reticle may be a transparent block of material covered with a pattern defined by a different opaque material. Various masks are fed into the lithography apparatus and used to form layers of a semiconductor device. The pattern defined in a particular mask or reticle corresponds to the features to be fabricated in one or more layers of a semiconductor device. Often, multiple masks or reticles are fed into the lithography apparatus automatically during manufacturing and used to form corresponding layers of the semiconductor device. Clamps (e.g., reticle stage reticle clamps) in the lithography apparatus are used to secure the mask or reticle during processing. The membranes associated with these clamps require periodic inspection. For example, inspection may be required if the membrane is suspected to be contaminated or damaged. Inspection may also be required as part of normal routine maintenance. Typically, inspection requires the shutdown of the lithography apparatus and the manufacturing process. A temporary structure with a camera is attached to the lithography apparatus and the inspection is performed manually by a technician. This testing typically takes several hours to complete, exposes the environment within the lithographic apparatus to ambient conditions, may introduce contaminants into the system, and / or has other drawbacks.

[0036] In contrast, the disclosed system and method provides an inspection system configured to be used to in-situ inspect a membrane associated with a reticle stage clamp of a lithographic apparatus while the lithographic apparatus continues to operate. The clamp comprises a number of components configured to support and provide a connection to a chuck body. The membrane is the portion of the clamp that contacts the reticle. The inspection system is configured to be automatically inserted into and handled by the lithographic apparatus, similar to how any other mask or reticle is automatically inserted into and handled by the lithographic apparatus. Inspecting a lithographic apparatus using the disclosed inspection system saves hours of downtime associated with conventional inspection methods. Furthermore, the disclosed system is configured to avoid exposing the environment inside the lithographic apparatus to ambient conditions and avoid contamination of the membrane and / or other parts of the lithographic apparatus (e.g., reticle handler robot gripper) by contamination from manual membrane inspection tools or introduced by a user performing manual inspection / maintenance.

[0037] Although specific reference is made herein to the manufacture of integrated circuits (ICs), it should be understood that the description herein has many other possible applications. For example, it may be used in the manufacture of integrated optical systems, induction and detection patterns for magnetic domain memories, liquid crystal display panels, thin film magnetic heads, and the like. Those skilled in the art will appreciate that in the context of such alternative applications, the terms "reticle," "wafer," or "die" herein should be considered interchangeable with the more general terms "mask," "substrate," and "target portion," respectively. Furthermore, the terms "reticle" or "mask" herein may be considered synonymous with the more general term "patterning device."

[0038] First, before transferring a pattern from a patterning device, such as a mask, to the substrate, the substrate may undergo various procedures such as priming, resist coating, and a soft bake. After exposure, the substrate may undergo other procedures ("post-exposure procedures") such as a post-exposure bake (PEB), development, a hard bake, measurement and / or other inspection of the transferred pattern. This sequence of procedures is used as the basis for creating an individual layer of a device, such as an IC. The substrate may then undergo various processes such as etching, ion implantation (doping), metallization, oxidation, chemical-mechanical polishing, and the like, all to finish off the individual layers of the device. If the device requires multiple layers, the entire procedure, or a variant thereof, is repeated for each layer. Eventually, there will be a device on each target portion on the substrate. These devices are then separated from one another by techniques such as dicing or sawing, allowing the individual devices to be mounted on carriers or connected to pins.

[0039] The manufacture of devices, such as semiconductor devices, typically involves processing a substrate (e.g., a semiconductor wafer) using a number of manufacturing processes to form various features and layers of the device. Such layers and features are typically manufactured and processed using deposition, lithography, etching, chemical mechanical polishing, ion implantation, and / or other processes. Multiple devices may be manufactured on multiple dies on a substrate and then separated into individual devices. This device manufacturing process may be considered a patterning process. A patterning process includes a patterning step, such as optical lithography and / or nanoimprint lithography, using a patterning device in a lithography apparatus to transfer a pattern on the patterning device to a substrate, and typically, but optionally, includes one or more associated pattern processing steps, such as developing a resist in a developer, baking the substrate using a bake tool, and etching with the pattern using an etcher. A patterning process typically includes one or more metrology processes.

[0040] Lithography is a process in the manufacture of devices such as integrated circuits, in which patterns formed on a substrate define the functional elements of devices such as microprocessors and memory chips. Similar lithographic techniques are also used in the formation of flat panel displays, microelectromechanical systems (MEMS), and other devices.

[0041] As semiconductor manufacturing processes improve, the dimensions of functional elements are continually reduced while the number of functional elements, such as transistors, per device has steadily increased for decades, following a trend commonly referred to as "Moore's Law. " At the current state of technology, the layers of a device are fabricated using lithographic projection apparatus that projects a design layout onto a substrate using illumination from a deep ultraviolet illumination source, creating individual functional elements with dimensions significantly below 100 nm, i.e., less than half the wavelength of the radiation from the illumination source (e.g., a 193 nm illumination source).

[0042] This process, in which features with dimensions smaller than the classical resolution limit of the lithographic projection apparatus are printed, is commonly known as low k1 lithography, following the resolution formula CD=k1×λ / NA, where λ is the wavelength of the radiation used (currently most often 248 nm or 193 nm), NA is the numerical aperture of the projection optics of the lithographic projection apparatus, CD is the "critical dimension", the smallest feature size that will typically be printed, and k1 is an empirical resolution factor. In general, the smaller k1 is, the more difficult it is to reproduce a pattern on a substrate that resembles the shape and dimensions planned by the designer to achieve a particular electrical function and performance. To overcome these difficulties, sophisticated fine-tuning steps are applied to the lithographic projection apparatus, the design layout, or the patterning device. These include, for example, but are not limited to, optimization of NA and optical coherence settings, customized illumination schemes, the use of phase-shifting patterning devices, optical proximity correction (OPC, also known as "optical and process correction") in the design layout, or other methods commonly defined as "resolution enhancement techniques" (RET).

[0043] The term "projection optics" as used herein should be broadly interpreted to encompass various types of optics including, for example, refractive optics, reflective optics, apertures, catadioptric optics. The term "projection optics" may include components that operate according to any of these design types to collectively or individually direct, shape or control a projection beam of radiation. The term "projection optics" may include any optical element in a lithographic projection apparatus, regardless of where the optical element is located on the optical path of the lithographic projection apparatus. The projection optics may include optical elements for shaping, conditioning and / or projecting radiation from a radiation source before the radiation passes through a patterning device and / or may include optical elements for shaping, conditioning and / or projecting radiation after the radiation has passed through a patterning device. The projection optics generally does not include a radiation source and a patterning device.

[0044] 1 illustrates diagrammatically an embodiment of a lithographic apparatus LA included in and / or associated with a system and / or method of the present disclosure. The apparatus comprises an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV, DUV or EUV radiation), a support structure (e.g. mask table) MT constructed to support a patterning device (e.g. mask) MA and connected to a first positioner PM configured to accurately position the patterning device according to certain parameters, a substrate table (e.g. wafer table) WT (e.g. WTa, WTb or both) configured to hold a substrate (e.g. resist coated wafer) W and coupled to a second positioner PW configured to accurately position the substrate according to certain parameters, and a projection system (e.g. refractive projection lens system) PS configured to project a pattern imparted by the patterning device MA to the radiation beam B onto a target portion C (e.g. comprising one or more dies, often referred to as a field) of the substrate W. The projection system is supported on a reference frame (RF). As depicted, the apparatus is of a transmissive type (e.g. employing a transmissive mask) Alternatively, the apparatus may be of a reflective type (e.g. employing a programmable mirror array of a type as described above, or employing a reflective mask).

[0045] The illuminator IL receives a beam of radiation from the radiation source SO. The source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In such cases the source is not considered to be a part of the lithographic apparatus and the radiation beam is passed from the source SO to the illuminator IL with the aid of a beam delivery system BD, for example comprising suitable directing mirrors and / or beam expanders. In other cases the source may be an integral part of the apparatus, for example when the source is a mercury lamp. The source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system.

[0046] The illuminator IL may modify the intensity distribution of the beam. The illuminator may be configured to limit the radial extent of the radiation beam such that the intensity distribution is non-zero within an annular region in a pupil plane of the illuminator IL. Additionally or alternatively, the illuminator IL may be operable to limit the distribution of the beam in the pupil plane such that the intensity distribution is non-zero within a number of equally spaced sectors in the pupil plane. The intensity distribution of the radiation beam in the pupil plane of the illuminator IL may be referred to as an illumination mode.

[0047] The illuminator IL may comprise an adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam. Typically, at least the outer and / or inner radial extent (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in a pupil plane of the illuminator may be adjusted. The illuminator IL may be operable to change the angular distribution of the beam. For example, the illuminator may be operable to change the number and angular extent of non-zero sectors of the intensity distribution in the pupil plane. By adjusting the intensity distribution of the beam in the pupil plane of the illuminator, different illumination modes may be realized. For example, by limiting the radial and angular extent of the intensity distribution in the pupil plane of the illuminator IL, the intensity distribution may have a multipole distribution, e.g. a dipole, quadrupole or hexapole distribution. A desired illumination mode may be obtained, for example, by inserting an optical system providing that illumination mode into the illuminator IL or by using a spatial light modulator.

[0048] The illuminator IL may be operable to change the polarization of the beam using the adjuster AD or may be operable to adjust the polarization. The polarization state of the radiation beam across a pupil plane of the illuminator IL may be referred to as the polarization mode. The use of different polarization modes may enable the realization of higher contrast in the image formed on the substrate W. The radiation beam may be unpolarized. Instead, the illuminator may be configured to linearly polarize the radiation beam. The polarization direction of the radiation beam may vary across the pupil plane of the illuminator IL. The polarization direction of the radiation may be different in different regions of the pupil plane of the illuminator IL. The polarization state of the radiation may be selected depending on the illumination mode. In the case of a multipole illumination mode, the polarization of each pole of the radiation beam may be approximately orthogonal to the position vector of that pole in the pupil plane of the illuminator IL. For example, in the case of a dipole illumination mode, the radiation may be linearly polarized in a direction substantially orthogonal to the bisector of two opposite sectors of a dipole. The radiation beam may be polarized in one of two different orthogonal directions, which may be referred to as the X and Y polarization states. In the case of a quadrupole illumination mode, the radiation in each pole sector may be linearly polarized in a direction substantially orthogonal to the bisector of that sector. This polarization mode may be referred to as XY polarization. Similarly, in the case of a hexapole illumination mode, the radiation in each pole sector may be linearly polarized in a direction substantially orthogonal to the bisector of that sector. This polarization mode may be referred to as TE polarization.

[0049] The illuminator IL will generally comprise various other components, such as an integrator IN and a condenser CO. The illumination system may include various types of optical elements, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical elements, or any combination thereof, for directing, shaping or controlling radiation. Thus, the illuminator provides a conditioned radiation beam B having a desired uniformity and a desired intensity distribution in its cross-section.

[0050] The support structure MT supports the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as whether or not the patterning device is held in a vacuum environment. The support structure may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device. The support structure may be for example a frame or a table, which may be fixed or movable as required. The support structure may ensure that the patterning device is at a desired position, for example with respect to the projection system.

[0051] The term "patterning device" as used herein should be broadly interpreted as referring to any device that can be used to impart a pattern to a target portion of a substrate. In an embodiment, the patterning device is any device that can be used to impart a radiation beam with a pattern in its cross-section to generate a pattern in the target portion of the substrate. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so-called assist features. Generally, the pattern imparted to the radiation beam will correspond to a particular functional layer of a device to be created in the target portion of the device, such as an integrated circuit.

[0052] A patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as 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 so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern to the radiation beam, which is reflected by the mirror matrix.

[0053] The term "projection system" as used herein should be interpreted broadly as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, appropriate for the exposure radiation used or other factors, such as the use of an immersion liquid or the use of a vacuum. The term "projection lens" as used herein may be considered as synonymous with the more general term "projection system".

[0054] The projection system PS has an optical transfer function that may not be uniform, which may affect the pattern imaged onto the substrate W. For unpolarized radiation, such effects can be described fairly well by two scalar maps that describe the transmission (apodization) and relative phase (aberration) of the radiation leaving the projection system PS as a function of position in its pupil plane. These scalar maps may be called the transmission map and the relative phase map, and may be expressed as linear combinations of a complete set of basis functions. A convenient set are the Zernike polynomials, which form a set of orthogonal polynomials defined on the unit circle. Determining each scalar map may involve determining the coefficients of such an expansion. As the Zernike polynomials are orthogonal on the unit circle, the Zernike coefficients can be determined by calculating the dot product of the scalar map to be measured with each Zernike polynomial in turn, and dividing this by the square of the norm of that Zernike polynomial.

[0055] The transmission map and the relative phase map are field and system dependent; that is, in general, each projection system PS will have a different Zernike expansion for each field point (i.e. for each spatial location in its image plane). The relative phase in the pupil plane of the projection system PS may be determined, for example, by projecting radiation from a point source in the object plane of the projection system PS (i.e. the plane of the patterning device MA) through the projection system PS and measuring the wavefront (i.e. the locus of points with the same phase) using a shearing interferometer. A shearing interferometer has the advantage that it is a common-path interferometer and therefore does not require a secondary reference beam to measure the wavefront. The shearing interferometer may comprise a diffraction grating, for example a two-dimensional grid, in the image plane of the projection system (i.e. the substrate table WTa or WTb) and a detector arranged to detect an interference pattern in a plane conjugate to the pupil plane of the projection system PS. The interference pattern is related to the derivative of the phase of the radiation with respect to the coordinate in the pupil plane in the shear direction. The detector may comprise an array of sensing elements, for example a charge-coupled device (CCD).

[0056] Since the projection system PS of the lithographic apparatus may not generate visible fringes, the accuracy of the wavefront determination can be increased using phase stepping techniques, for example by moving a diffraction grating. The stepping may be performed in the plane of the diffraction grating or in a direction orthogonal to the scan direction of the measurement. The step range may be one period of the grating and at least three (uniformly distributed) phase steps may be used. Thus, for example, three scan measurements may be performed in the y direction, each at a different position in the x direction. This stepping of the diffraction grating effectively converts the phase change into an intensity change, allowing the determination of the phase information. The grating may be stepped in a direction perpendicular to the diffraction grating (z direction) in order to calibrate the detector.

[0057] The diffraction grating may be scanned sequentially in two orthogonal directions, which may coincide with the axes (x and y) of the coordinate system of the projection system PS or may be at an angle, such as 45 degrees, to these axes. The scan may be performed over an integer multiple of the grating period, for example over one period of the grating. The scan averages the phase change in one direction and allows the reconstruction of the phase change in the other direction. This allows the wavefront to be determined as a function of both directions.

[0058] The transmission (apodization) in the pupil plane of the projection system PS may be determined by projecting radiation through the projection system PS, for example from a point source in the object plane of the projection system PS (i.e. in the plane of the patterning device MA), and measuring the intensity of the radiation in a plane conjugate to the pupil plane of the projection system PS using a detector. The same detector may be used as is used to measure the wavefront and determine the aberrations.

[0059] The projection system PS may comprise a number of optical elements (e.g., lenses) and may further comprise an adjustment mechanism configured to adjust one or more optical elements to correct aberrations (phase changes across the pupil plane across the field). To achieve this, the adjustment mechanism may be operable to manipulate one or more optical elements (e.g., lenses) in the projection system PS in one or more different ways. The projection system may have a coordinate system whose optical axis extends in the z-direction. The adjustment mechanism may be operable to perform any combination of displacing one or more optical elements, tilting one or more optical elements, and / or deforming one or more optical elements. The displacement of the optical elements may be in any direction (x, y, z, or a combination thereof). The tilting of the optical elements is typically performed by rotating them out of a plane perpendicular to the optical axis about an axis in the x and / or y directions, although for non-rotationally symmetric aspheric optical elements, a rotation about the z-axis may be used. The deformation of the optical elements may include low-frequency shapes (e.g., astigmatism) and / or high-frequency shapes (e.g., freeform aspheric surfaces). The deformation of the optical element may be performed, for example, by exerting a force on one or more sides of the optical element using one or more actuators and / or by heating one or more selected areas of the optical element using one or more heating elements. In general, it may not be possible to adjust the projection system PS to correct for apodization (transmittance variation across the pupil plane). A transmittance map of the projection system PS may be used when designing a patterning device (e.g., mask) MA for the lithographic apparatus LA. Using computational lithography techniques, the patterning device MA may be designed to at least partially correct for the apodization.

[0060] The lithographic apparatus may be of a type having two or more stages (dual stage, or e.g. two or more substrate tables WTa, WTb, two or more patterning device tables, substrate table WTa and a substrate-free table WTb below the projection system, e.g. dedicated to assisting in measurement and / or cleaning etc.). Such a "multi-stage" machine may use additional tables in parallel, or may use one or more other tables for exposure whilst preparatory steps are performed on one or more tables. For example alignment measurements using alignment sensors AS and / or level (height, tilt etc.) measurements using level sensors LS may be performed.

[0061] The lithographic apparatus may be of a type in which at least a part of the substrate is covered by a liquid having a relatively high refractive index, e.g. water, so as to fill a space between the projection system and the substrate. Immersion liquids may also be applied to other spaces in the lithographic apparatus, for example between the patterning device and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. The term "immersion" as used herein does not imply that a structure such as the substrate has to be submerged in liquid, but simply that a liquid is located between the projection system and the substrate during exposure.

[0062] During operation of the lithographic apparatus, a radiation beam is conditioned and provided by an illumination system IL. The radiation beam B is incident on a patterning device (e.g. mask) MA, which is held on a support structure (e.g. mask table) MT, and is patterned by the patterning device. After passing the patterning device MA, the radiation beam B passes through a projection system PS which focuses the beam onto a target portion C of a substrate W. With the aid of a second positioner PW and a position sensor IF (e.g. an interferometer device, a linear encoder, a 2D encoder, or a capacitive sensor), the substrate table WT can be precisely moved, e.g. to position different target portions C in the path of the radiation beam B. Similarly, the first positioner PM and another position sensor (not explicitly shown in FIG. 1 ) can precisely position the patterning device MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library or during a scan. In general, movement of the support structure MT may be realised with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate table WT may be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner) the support structure MT may be connected to a short-stroke actuator only, or may be fixed. The patterning device MA and the substrate W may be aligned using the patterning device alignment marks M1, M2 and substrate alignment marks P1, P2. The substrate alignment marks as illustrated occupy dedicated target portions, but may also be located in spaces between the target portions (these are referred to as scribe-line alignment marks). Similarly, in situations in which the patterning device MA is provided with more than one die, the patterning device alignment marks may be located between the dies.

[0063] The depicted apparatus may be used in at least one of the following modes: 1. In step mode, the support structure MT and the substrate table WT are kept essentially stationary and a pattern imparted to the radiation beam is projected onto the target portion C in one go (i.e. a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that another target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure. 2. In scan mode, the support structure MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam is projected onto the target portion C (i.e. a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure MT may be determined by the (de-)magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width of the target portion in a single dynamic exposure (non-scanning direction), whereas the length of the scanning motion determines the height of the target portion (scanning direction). 3. In another mode, the support structure MT is kept essentially stationary holding the programmable patterning device and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam is projected onto the target portion C. In this mode, a pulsed radiation source is typically employed and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan. This mode of operation is readily applicable to maskless lithography using a programmable patterning device such as a programmable mirror array of the type referred to above. Combinations and variations of the above modes or entirely different modes may also be employed.

[0064] The substrate may be processed, before or after exposure, for example in a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) or a metrology tool or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Additionally, a substrate may be processed multiple times, for example to produce a multi-layer IC, and thus the term substrate as used herein may refer to a substrate that already includes multiple processed layers.

[0065] As used herein, the terms "radiation" and "beam" encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., having a wavelength of 365, 248, 193, 157, or 126 nm), extreme ultraviolet (EUV) radiation (e.g., having a wavelength in the range of 5 to 20 nm), and particle beams such as ion beams and electron beams.

[0066] Various patterns on or provided by a patterning device may have different process windows, i.e., a space of processing variables within which patterns will be produced within specifications. Examples of pattern specifications related to potential systematic defects include checks for necking, line pullback, thinning, critical dimension (CD), edge placement, overlap, resist top loss, resist undercut, and / or bridging. The process window of a pattern on a patterning device or on a region thereof may be obtained by merging (e.g., overlapping) the process windows of each individual pattern. The boundary of the process window of a group of patterns comprises the boundaries of the process windows of several of the individual patterns. In other words, these individual patterns limit the process window of the group of patterns. These patterns may be referred to as "hot spots" or "process window limiting patterns (PWLPs)" and are used interchangeably herein. When controlling parts of the patterning process, it is possible and economical to focus on hot spots. If the hot spots are free of defects, it is highly likely that other patterns are free of defects as well.

[0067] As shown in FIG. 2, the lithographic apparatus LA may form part of a lithographic cell LC, also called a lithocell or cluster, which also includes apparatus for performing pre-exposure and post-exposure processes on the substrate. Typically, these include one or more spin coaters SC for depositing one or more resist layers, one or more developers for developing the exposed resist, one or more chill plates CH, and / or one or more bake plates BK. A substrate handler, or robot RO, picks up one or more substrates from the input / output ports I / O1, I / O2, moves them between the different process apparatus, and delivers them to a loading bay LB of the lithographic apparatus. Collectively, these apparatuses, often called a track, are under the control of a track control unit TCU, which is itself controlled by a supervisory control system SCS, which also controls the lithographic apparatus via a lithographic control unit LACU. Thus, the various apparatuses can be operated to maximize throughput and processing efficiency.

[0068] To ensure that a substrate exposed by a lithographic apparatus is accurately and consistently exposed and / or to monitor a portion of a patterning process (e.g., a device manufacturing process) that includes at least one pattern transfer step (e.g., an optical lithography step), it is desirable to inspect a substrate or other object to measure or determine one or more properties, such as alignment, overlay (e.g., between structures of a higher layer or between structures of the same layer that are provided separately on the same layer, e.g., by a double patterning process), linewidth, critical dimension (CD), focus offset, material properties, etc. For example, contamination on a reticle clamping membrane (e.g., as described herein) may adversely affect overlay because clamping a reticle over such contamination will distort the reticle. Thus, a manufacturing facility in which the lithocell LC is located typically also includes a metrology system that measures some or all of a substrate W (FIG. 1) that has been processed in the lithocell, or other objects in the lithocell. The metrology system may be part of the lithographic apparatus LA, such as an alignment sensor AS (FIG. 1).

[0069] The one or more measurement parameters may include, for example, alignment, overlay between successive layers formed in or on the patterned substrate, critical dimension (CD) (e.g., critical linewidth) of features formed in or on the patterned substrate, focus or focus error of the optical lithography process, dose or dose error of the optical lithography process, optical aberrations of the optical lithography process, etc. The measurements may be performed on targets on the product substrate itself and / or on dedicated metrology targets provided on the substrate. Measurements may be performed after resist development and before etch, after etch, after deposition, and / or at other times.

[0070] There are various techniques for measuring structures formed in a patterning process, including the use of scanning electron microscopes, image-based metrology tools, and / or various specialized tools. As mentioned above, a fast, non-invasive type of specialized metrology tool is one in which a beam of radiation is directed at a target on the surface of a substrate and properties of the scattered (diffracted / reflected) beam are measured. By evaluating one or more properties of the radiation scattered by the substrate, one or more properties of the substrate can be determined. This may be referred to as diffraction-based metrology. One application of this diffraction-based metrology is the measurement of the asymmetry of features in a target. This can be used, for example, as a measure of overlay, although other applications are known. For example, the asymmetry can be measured by comparing opposite parts of the diffraction spectrum (e.g., comparing the −1st and +1st orders of the diffraction spectrum of a periodic grating). This can be performed as described above and, for example, in U.S. Patent Application Publication No. 2006-066855, which is incorporated herein by reference in its entirety. Another application of diffraction-based metrology is the measurement of feature width (CD) in a target.

[0071] Thus, in a device manufacturing process (e.g., a patterning process, a lithography process, etc.), various types of measurements may be made on a substrate or other object during or after the process. The measurements may determine whether a particular substrate is defective, may establish an adjustment of the process or an apparatus used in the process (e.g., the alignment of two layers on a substrate, or the alignment of a patterning device relative to a substrate), may measure the performance of the process and the apparatus, or may be for other purposes. Examples of measurements include optical imaging (e.g., optical microscopes), non-imaging optical measurements (e.g., diffraction-based measurements such as ASML Yield Star metrology tool, ASML SMASH metrology system), mechanical measurements (e.g., stylus-based profiling, atomic force microscope (AFM)), and / or non-optical imaging (e.g., scanning electron microscope (SEM)). The SMASH (SMart Alignment Sensor Hybrid) system, as described in U.S. Pat. No. 6,961,116, the entire contents of which are incorporated herein by reference, employs a self-referencing interferometer that generates two overlapping, relatively rotated images of an alignment marker, detects the intensity in the pupil plane where interference of the Fourier transforms of the images occurs, and extracts position information from the phase difference between the diffraction orders of the two images, which appears as an intensity change in the interfered orders.

[0072] The metrology results may be provided directly or indirectly to the supervisory control system SCS. If an error is detected, adjustments may be made to the exposure of subsequent substrates (particularly if inspection can be performed immediately and one or more other substrates of the batch have not yet been exposed) and / or to subsequent exposures of the exposed substrate. Also, already exposed substrates may be stripped and reworked to improve yield, or may be discarded, thereby avoiding further processing on substrates that are known to be defective. If only some target portions of a substrate are defective, further exposures may be performed only on those target portions that meet specification.

[0073] Within a metrology system, a metrology apparatus is used to determine one or more properties of the substrate, and in particular how one or more properties vary for different substrates or different layers of the same substrate. As mentioned above, the metrology apparatus may be integrated into the lithographic apparatus LA or lithocell LC, or may be a stand-alone device.

[0074] To enable metrology, one or more targets can be provided on the substrate. In some embodiments, the targets are specially designed and may comprise periodic structures. In some embodiments, the targets are part of a device pattern, e.g., the periodic structure of a device pattern. In some embodiments, the device pattern is a periodic structure of a memory device, e.g., structures such as bipolar transistors (BPTs), bit line contacts (BLCs), etc.

[0075] In some embodiments, a target on a substrate may include one or more 1D periodic structures (e.g., gratings) that are printed such that after development, periodic structure features are formed of hard resist lines. In some embodiments, a target may include one or more 2D periodic structures (e.g., gratings) that are printed such that after development, one or more periodic structures are formed of hard resist pillars or vias in the resist. The bars, pillars, or vias may be etched into the substrate (e.g., one or more layers on the substrate).

[0076] In an embodiment, one of the parameters of interest in the patterning process is overlay. Overlay can be measured using dark-field scatterometry, where the zeroth order of diffraction (corresponding to specular reflection) is blocked and only higher diffraction orders are processed. Examples of dark-field metrology can be found in PCT Patent Application Publications WO2009 / 078708 and WO2009 / 106279, which are incorporated by reference in their entirety. Further developments of this technology are described in US Patent Application Publications US2011-0027704, US2011-0043791, and US2012-0242970, which are incorporated by reference in their entirety. Diffraction-based overlay, using dark-field detection of diffraction orders, allows overlay measurements on smaller targets. These targets may be smaller than the illumination spot and surrounded by the structure of the device product on the substrate. In an embodiment, multiple targets can be measured in one radiation capture.

[0077] As lithography nodes continue to shrink, increasingly complex wafer designs may be implemented. Various tools and / or techniques may be used by designers to ensure that the complex designs are accurately transferred to the physical wafer. These tools and techniques may include mask optimization, source mask optimization (SMO), OPC, design for control, and / or other tools and / or techniques. For example, a source mask optimization process is described in U.S. Pat. No. 9,588,438, entitled "Optimization Flow for Source, Mask, and Projection Optics," which is incorporated by reference in its entirety.

[0078] The systems and / or methods of the present disclosure may be used as stand-alone tools and / or techniques, or may be used in combination with other semiconductor manufacturing processes, and may be used to assist in the accurate transfer of complex designs onto physical wafers.

[0079] As mentioned above, the system of the present disclosure comprises an inspection system configured to be used to inspect a portion of a lithographic apparatus in situ while the lithographic apparatus continues to operate. For example, the inspection system may simply replace a typical reticle that is inserted into the lithographic apparatus. The lithographic apparatus does not need to make any special adjustments to the inspection system during operation, since the lithographic apparatus only needs to move the inspection system through the typical movements and / or positions of the replaced reticle. In some embodiments, the portion of the lithographic apparatus to be inspected comprises a membrane associated with a reticle stage reticle clamp, and / or other portions of the lithographic apparatus. The inspection system is configured to be inserted into the lithographic apparatus and automatically processed (e.g., moved, rotated, etc.) by the lithographic apparatus in the same way that any other mask or reticle is inserted into the lithographic apparatus and automatically processed by the lithographic apparatus.

[0080] Inspecting a lithographic apparatus with the disclosed inspection system saves hours of downtime associated with conventional inspection methods. Additionally, the disclosed system is configured to avoid exposing the environment inside the lithographic apparatus to the ambient environment, avoid contaminating other parts of the lithographic apparatus (e.g., reticle handler robot grippers) with material removed from the membrane, and / or have other advantages.

[0081] In some embodiments, the systems of the present disclosure include an inspection system, one or more processors included in a computing system, and / or other components. As a non-limiting example, FIGS. 3A and 3B show (a part of) a lithographic apparatus 300 (e.g., similar or identical to the lithographic apparatus shown in FIG. 1). FIG. 3A shows an inspection system 302 and various components of the lithographic apparatus 300, including tool handlers 306, 307, 308, a reticle stage 310, a reticle clamp 312 (only one side is visible in FIG. 3A), and / or other components. In some embodiments, the lithographic apparatus 300 is configured for deep ultraviolet (DUV) lithography. In some embodiments, a similar apparatus may be configured for extreme ultraviolet (EUV) lithography. In some embodiments, the inspection system 302 comprises a body, one or more image acquisition devices, one or more light sources, electronics, a power source, one or more identification features, one or more processors and / or computing systems as described above, and / or other components. These components are described in turn below.

[0082] In some embodiments, tool handlers 306, 307, 308 include reticle handler turret gripper 306, reticle handler robot gripper 307 (having associated clamps 308, etc. for gripping a reticle), and / or other components. Reticle handler robot gripper 307 may, for example, move a reticle from pod 320 (e.g., after a user places the reticle in pod 320). Reticle handler turret gripper 306 may, for example, move a reticle from reticle handler robot gripper 307 to reticle clamp 312. Lithographic apparatus 300 may include various other mechanical components 322 (translation mechanisms, lifting mechanisms, rotation mechanisms, motors, power generation and transmission components, structural components, etc.) configured to assist in movement and control of inspection system 302 through lithographic apparatus 300.

[0083] The inspection system 302 is configured to be used to in-situ inspect a membrane associated with a clamp 312 of the lithographic apparatus 300 (e.g., a membrane of the clamp in contact with the underside of a reticle) while the lithographic apparatus 300 continues to operate. The inspection system 302 is configured to be inserted into the lithographic apparatus 300 and automatically processed by the lithographic apparatus 300 in the same manner as any other mask or reticle 316 would be automatically inserted into the lithographic apparatus 300 and processed by the lithographic apparatus 300. For example, the inspection system 302 is sized and shaped to be inserted into the lithographic apparatus 300 at a typical insertion point 318 using a typical insertion method in the same manner as any other reticle 316 would be inserted into the apparatus 300.

[0084] Figure 3B is an expanded view of a portion of apparatus 300. Figure 3B shows inspection system 302, reticle handler turret gripper 306, reticle stage 310, reticle stage reticle clamp 312 (only one side is visible in Figure 3B), machine components 322, reticle handler robot gripper 307, and / or other components. As shown in Figure 3B, reticle handler turret gripper 306 is configured to move inspection system 302 from reticle handler robot gripper 307 to reticle clamp 312 so that inspection system 302 can be used to inspect a membrane associated with clamp 312 in situ. Moving inspection system 302 may comprise moving the inspection system horizontally, vertically, and / or other directions toward or away from membrane and clamp 312. The reticle handler turret gripper 306 and / or the reticle handler robot gripper 307 may include various motors, translation devices, rotational components, clamps, clips, power supplies, power transmission components, vacuum mechanisms, and / or other components that assist in moving the inspection system 302.

[0085] FIG. 4 illustrates an example embodiment of an inspection system 302 (FIGS. 3A and 3B). FIG. 4 illustrates a bottom view 401 and a side view 403 of the inspection system 302. As illustrated in FIG. 4, the inspection system 302 includes a body 402, one or more image capture devices 404, one or more light sources 406, electronics 408, a power source 410, one or more identification features 412, and / or other components. The various components of the inspection system 302 illustrated in FIG. 4 may be coupled in any arrangement and with any coupling components that enable the inspection system 302 to function as described herein. For example, the various components of the inspection system 302 may be coupled together with clamps, clips, adhesives, screws, nuts, collars, and / or other coupling mechanisms. In some embodiments, the inspection system 302 includes and / or is configured to communicate with one or more processors and / or computing systems, as described below (see FIG. 11).

[0086] The body 402 is configured to be inserted into a lithographic apparatus, engaged by a tool handler (described above) of the lithographic apparatus, and positioned by the tool handler to inspect a portion of the lithographic apparatus. In some embodiments, the portion of the lithographic apparatus comprises a chuck membrane associated with a reticle stage reticle clamp (described above). The body 402 has a rectangular shape. As described above, the tool handler comprises a reticle handler and a turret gripper (see the discussion of Figures 3A and 3B above). The reticle handler is configured to move the body 402 from a load port of the lithographic apparatus to the turret gripper, which is configured to grip the body 402 at one or more edges and / or other surfaces of the body 402, move the body 402 to a position adjacent to the portion of the lithographic apparatus, and adjust the position of the body 402.

[0087] The body 402 typically has a shape similar or identical to a reticle that is engaged and positioned by a tool handler. For simplicity and ease of the following description, FIG. 4 illustrates the body 402 as a single block of material formed from an opaque material and having a rectangular parallelepiped shape. This is not intended to be limiting. In some embodiments, one or more portions of the body 402 may be formed from a transparent or nearly transparent material, such as extra-low thermal expansion quartz (SFS), a transparent material, such as glass, an opaque material, such as a metal, polymer, ceramic, and / or other material. The body 402 may be manufactured using any number of materials, so long as the external dimensions and mass comply with, for example, SEMI Standard P1 for Hard Surface Photomask Substrates.

[0088] One or more image capture devices 404 are coupled to the body 402. The image capture devices 404 are configured to capture one or more images of a portion (e.g., a membrane) of a lithographic apparatus (e.g., the lithographic apparatus 300 shown in FIGS. 3A and 3B) when the body 402 is positioned by a tool handler. The one or more image capture devices 404 are configured to capture one or more images having a particular focus, zoom level, and / or other characteristics. In some embodiments, the one or more image capture devices comprise one or more optical cameras. The one or more cameras may be, for example, compact with high magnification, high resolution, and / or other characteristics.

[0089] In FIG. 4, four image capture devices 404 are shown. This is not intended to be limiting. The number, location, and / or orientation of the image capture devices 404 may be varied based on the resolution requirements, the field of view of the individual image capture devices 404, and / or other factors. In some embodiments, the image capture devices 404 may be coupled to the body 402 at different locations (and / or different orientations) such that the image capture devices acquire different, overlapping images of different portions of a film of a lithographic apparatus (e.g., the lithographic apparatus 300 shown in FIGS. 3A and 3B). For example, the individual image capture devices 404 may be positioned at different locations on the body 402 relative to each other, relative to one or more light sources 406, and / or relative to other components. The different locations may cause the individual image capture devices 404 to acquire images of different portions of a film surface (or films) of the lithographic apparatus.

[0090] The one or more light sources 406 are configured to illuminate a portion of the lithographic apparatus (e.g., a film) imaged by the image capture device 404. An individual light source 406 may be associated with one or more individual image capture devices 404. For example, as shown in FIG. 4, one light source 406 and one image capture device 404 are disposed proximate to one another on the body 402. The light sources 406 are coupled to the body 402 at a location proximate to the image capture devices 404 such that each light source 406 provides light or illumination to an area imaged by the corresponding image capture device 404. However, other configurations are contemplated. In some embodiments, the light sources 406 may be configured to provide illumination such that one or more identification features 412 are visible before, during, and / or after inspection.

[0091] In some embodiments, the light sources 406 each comprise a light emitting diode (LED). In some embodiments, the light sources 406 comprise an illumination guide and / or other components configured to direct illumination from the LEDs towards a film of the lithographic apparatus. For example, the illumination guide may include one or more cavities disposed near the light sources 406. The light sources 406 may include various channels, reflective surfaces, and the like configured to direct light for imaging. In some embodiments, instead of and / or in addition to LEDs, the light sources 406 may comprise one or more mirrors and / or other reflective surfaces configured to direct ambient light from the surrounding atmosphere towards one or more films to be imaged. In some embodiments, illumination may be provided by "glow in the dark" paint or other similar products such as vials of tritium and / or other materials.

[0092] The body 402 includes a power source 410 of electrical energy, such as a battery, and / or other power source for the image capture device 404 and / or the light source 406, includes wiring connecting the power source 410 to other components of the system 302, and / or includes other components that configure the inspection system 302 to function as described herein. The power source 410 is shown in FIG. 4 at or near the center of the body 402, but is not limited thereto. The power source 410 may be located anywhere that enables the inspection system 302 to function as described herein.

[0093] The electronics 408 are coupled to the body 402, the image capture device 404, the light source 406, the power source 410, and / or other components. In some embodiments, the electronics 408 is configured to receive and store one or more images from the one or more image capture devices 404. For example, the electronics 408 may comprise an electronic storage medium that electronically stores information. The electronic storage medium may comprise one or both of system storage that is integral with the inspection system 302 (i.e., substantially non-removable) and / or removable storage that is removably connectable to the inspection system 302, for example, via a port (e.g., USB port, FireWire port, etc.) or drive (e.g., disk drive, etc.). The electronics 408 may comprise one or more of an optically readable storage medium (e.g., optical disk, etc.), a magnetically readable storage medium (e.g., magnetic tape, magnetic hard drive, floppy drive, etc.), a charge-based storage medium (e.g., EPROM, RAM, etc.), a solid-state storage medium (e.g., flash drive, etc.), and / or other electronically readable storage medium. The electronics 408 may store information, such as one or more images received from the image capture device 404, and / or other information that enables the inspection system 302 (FIGS. 3A, 3B) to function properly.

[0094] In some embodiments, the electronics 408 includes a transmitter and / or other components configured to wirelessly communicate information to and from one or more image capture devices 404. The information may be, for example, one or more images and / or may include one or more images and / or other information. This communication may be performed with or without first storing the one or more images, as described above. This communication may be performed with an external computing system (e.g., including one or more processors described herein and in connection with FIG. 11 ) and / or other devices. In some embodiments, the communication may be performed in real-time or near real-time. In some embodiments, this may comprise, for example, a live stream. In some embodiments, the electronics 408 may be configured to communicate some information in real-time or near real-time, while storing other information in electronic storage for later transfer to the external computing system.

[0095] In some embodiments, the body 402 comprises one or more identification features 412. The one or more identification features 412 comprise one or more of a label 413, a bar code 415, an alignment mark 417, and / or other identification features. The body 402 is configured such that the identification features 412 are visible to a user and / or a lithographic apparatus (e.g., the lithographic apparatus 300 shown in FIGS. 3A-3B ) such that the body 402 can be properly identified, loaded into, received by, and positioned for inspection by the lithographic apparatus 300.

[0096] In some embodiments, the inspection system 302 includes and / or is configured to communicate with one or more processors and / or computing systems (see processors 1104 and 1105 shown in FIG. 11). In some embodiments, the one or more processors and / or computing systems may be included in, for example, the lithographic apparatus 300 (FIGS. 3A, 3B) and / or may control software running on the lithographic apparatus 300. The one or more processors are configured with machine-readable instructions. The one or more processors are configured to receive one or more images from the one or more image acquisition devices, communicate data (in real-time or near real-time) between the electronics 408 and one or more external computing devices (which may include, for example, one or more processors), facilitate semi-automated or automated inspection of portions of the lithographic apparatus based on the one or more images, and / or perform other operations. The communication may be wireless, for example, as described below (in conjunction with FIG. 11).

[0097] In some embodiments, the one or more processors are configured to facilitate semi-automated inspection. Facilitating the semi-automated inspection comprises displaying one or more images to a user in real-time or near real-time using a user interface (e.g., see 1112-1116 described below in connection with FIG. 11). Facilitating the semi-automated inspection comprises receiving input and / or selection of control commands from a user via the user interface. These control commands may be received in real-time or near real-time as the one or more images are displayed to the user. In some embodiments, the control commands comprise, for example, live adjustments.

[0098] The control commands may comprise instructions to move the body 402 and the one or more image acquisition devices 404 based on a region of interest of the portion of the lithographic apparatus (e.g., 300 shown in FIG. 3A, FIG. 3B). The region of interest of the portion of the lithographic apparatus may be, for example, a particular area of ​​a film that appears contaminated in an image or is typically contaminated (e.g., determined based on a previous inspection) and / or other regions of interest. The control commands may comprise instructions to adjust focus, zoom, or other properties of the one or more image acquisition devices 404. For example, the image acquisition devices 404 may have electronically controllable focus settings, zoom settings, and the like. The control commands may comprise instructions to adjust illumination from one or more light sources 406 associated with the one or more image acquisition devices 404. For example, the light sources 406 may have electronically controllable brightness, wavelength (color), and / or other properties. As another example, the image acquisition devices 404 may have electronically controllable contrast settings. The control commands may comprise, for example, instructions to acquire an updated image using adjusted zoom, focus, and / or lighting, and / or other control commands. Facilitating the semi-automated inspection comprises displaying the updated image to a user with a user interface and enabling the user to determine the presence of contamination within the region of interest (e.g., the membrane or a particular portion of the membrane) based on the updated image.

[0099] In some embodiments, one or more images may be electronically stitched together (e.g., in real-time, near real-time, and / or at other times). The stitching may be performed by a user via a user interface, automatically by one or more processors, and / or otherwise. The stitching may be configured such that the stitched image includes a full (or near-full) view of the membrane surface over the distance that one or more image capture devices 404 move across the membrane. In some embodiments, images from individual image capture devices 404 may be electronically stitched together such that the stitched image includes a view of one or more target portions of the membrane (e.g., less than the entire membrane).

[0100] As a non-limiting example, Figure 5 illustrates one possible example of a semi-automated inspection flow 500. The flow 500 includes placing (502) the inspection system 302 (Figure 4) into a load port (insertion point 318 shown in Figure 3A) of the lithography apparatus 300 (Figures 3A, 3B), where a tool handler (such as 306, 307, 308 shown in Figure 3A) picks up (504), transports (506) the system 302, and lowers (508) the inspection system 302 into position for film inspection. One or more processors (see Figure 11) help the user control (510) the height and / or other position of the body 402 relative to the film (by controlling the tool handler). The one or more processors provide (512) a remote live stream of images of the film and stitch (514) two or more images for the user to view. The one or more processors help the user control (516) the zoom, focus, brightness, and / or other image set points (by controlling the image capture device 404 and / or the light source 406) and record (518) the image. Once imaging is complete, the inspection system 302 is returned (520) to the load port for removal from the lithographic apparatus 300.

[0101] Returning to FIG. 4, in some embodiments, the one or more processors are configured to assist in automated inspection. The automated inspection may be performed in real-time or near real-time as the one or more images are acquired. The automated inspection may comprise, for example, live adjustments. Assisting the automated inspection comprises automatically determining a region of interest of the portion of the lithographic apparatus based on the one or more images. The region of interest of the portion of the lithographic apparatus may be, for example, a particular predefined area of ​​the film that appears contaminated in the image or is typically contaminated (e.g., determined based on a previous inspection) and / or other regions of interest. Assisting the automated inspection comprises controlling a tool handler (FIG. 3A) to move the body 402 and the one or more image acquisition devices 404 based on the region of interest and / or other information. Assisting the automated inspection comprises adjusting a zoom and / or focus of the one or more image acquisition devices 404 based on the one or more images and / or other information, and adjusting illumination from one or more light sources 406 associated with the one or more image acquisition devices 404 based on the one or more images and / or other information. Facilitating the automated inspection may include causing one or more image capture devices 404 to capture updated images using adjusted focus and / or lighting, determining the presence of contamination in the region of interest based on the updated images, and / or other steps.

[0102] In some embodiments, the one or more processors are configured to support an automated (or semi-automated) inspection based on a trained machine learning algorithm. The trained machine learning algorithm is configured to receive one or more images and / or other information as input and output corresponding control commands. The corresponding control commands relate to determining an area of ​​interest, controlling a tool handler (FIG. 3A) to move the body 402 and one or more image acquisition devices 404, adjusting zoom and / or focus, adjusting lighting, causing the one or more image acquisition devices 404 to acquire updated images, determining the presence of contamination, and / or other commands. The trained machine learning algorithm is trained based on previously acquired images of a portion of the lithographic apparatus (e.g., the lithographic apparatus 300 shown in FIGS. 3A and 3B) with or without contamination, and / or other information. The previously acquired images are labeled with the area of ​​interest, the location of the body and / or imaging device relative to the area of ​​interest, the zoom and / or focus of the imaging device, lighting levels, an indication of whether contamination is present, and other labels. The performance of the lithographic apparatus is related to the contamination identified in the image, and correlation between the lithographic apparatus performance data and the image inspection data is used, for example, to label the images and / or to configure machine learning algorithms.

[0103] In some embodiments, the machine learning algorithm may be and / or include mathematical formulas, algorithms, plots, charts, networks (e.g., neural networks), and / or other tools and machine learning components. For example, the machine learning algorithm may be and / or include one or more neural networks having an input layer, an output layer, and one or more intermediate or hidden layers. In some embodiments, the one or more neural networks may be and / or include deep neural networks (e.g., neural networks having one or more intermediate or hidden layers between an input layer and an output layer).

[0104] As an example, one or more neural networks may be based on a large collection of neural units (or artificial neurons). One or more neural networks may roughly mimic the way biological brains work (e.g., via large clusters of biological neurons connected by axons). Each neural unit of a neural network may be connected to many other neural units of the neural network. Such connections can affect or inhibit the activation state of the connected neural units. In some embodiments, each individual neural unit may have a summing function that combines all its input values ​​together. In some embodiments, each connection (or the neural unit itself) may have a threshold function that prevents a signal from propagating to other neural units unless it exceeds a threshold. These neural network systems may be self-learning and trained rather than explicitly programmed, and may perform significantly better in certain areas of problem solving compared to traditional computer programs. In some embodiments, one or more neural networks may include multiple layers (e.g., layers in which signal paths pass from front to back layers). In some embodiments, backpropagation may be utilized by the neural network, where a prior stimulus is used to reset the weights of a "forward" neural unit. In some embodiments, stimuli and inhibitions for one or more neural networks may flow more freely, and connections may interact in more chaotic and complex ways. In some embodiments, intermediate layers of one or more neural networks include one or more convolutional layers, one or more recurrent layers, and / or other layers.

[0105] One or more neural networks may be trained (i.e., their parameters are determined) using a set of training information. The training information may include a set of training samples. Each sample may be a pair comprising an input object (usually a vector, which may be called a feature vector) and a desired output value (also called a supervisory signal). This may include labeled input images (with or without contamination) and corresponding control commands. A training algorithm adjusts the operation of the neural network by analyzing the training information and adjusting the parameters of the neural network (e.g., weights of one or more layers) based on the training information. For example, {(x1,y1),(x2,y2),…,(x N ,y N )}, and x i is the i-th feature vector, and y i If x is its supervisory signal, the training algorithm searches a neural network g: X → Y, where X is the input space and Y is the output space. A feature vector is an n-dimensional vector of numerical features that represent some object (such as a simulated aerial image, a wafer design, a paperclip, etc.). The vector space associated with these vectors is often called the feature space. After training, the neural network may be used to perform predictions with new samples.

[0106] In some embodiments, the trained machine learning algorithm comprises a neural network with an input layer, an output layer, and one or more hidden layers. In some embodiments, the trained machine learning algorithm comprises a convolutional neural network. A convolutional neural network is an artificial neural network that features one or more convolutional layers. A convolutional layer extracts features from an input image. Convolution preserves relationships between pixels by learning image features using small rectangles of input data. The input layer may go to a convolution block before being output to a convolution output block.

[0107] In some embodiments, the trained machine learning algorithm may implement an inverse residual structure where the input and output of the residual block are thin bottleneck layers. The residual layer may feed into the next layer and directly into one or more downstream layers. The bottleneck layer is a layer with a reduced number of neural units compared to the previous layer. The trained machine learning algorithm may use the bottleneck layer to obtain a dimensionality-reduced representation of the input image. An example of this uses an autoencoder with a bottleneck layer for nonlinear dimensionality reduction. The machine learning algorithm may also remove nonlinearities in the narrow layers to maintain expressiveness. In some embodiments, the design of the machine learning algorithm may be guided by a computational complexity metric (e.g., the number of floating-point operations). In some embodiments, instead of significantly increasing the dimensionality of the feature map at the neural unit that performs downsampling, the machine learning algorithm may increase the dimensionality of the feature map at all units to include as many locations as possible. In some embodiments, the machine learning algorithm may reduce the depth of the residual layer downstream and increase its width.

[0108] 6-9 show further illustrations of the inspection system 302 along with the lithographic apparatus 300. FIG. 6 shows the reticle handler turret gripper 306 gripping the inspection system 302. The engagement surfaces 601 are configured to grip the inspection system 302 in a position and orientation corresponding to the gripping feet 600 of the gripper 306. In this example, the surfaces 601 maintain a constant distance from each other corresponding to the distance between the feet 600. The surfaces 601 are also maintained perpendicular to the feet 600 to facilitate gripping by the feet 600. FIG. 7 shows a side view of the feet 600 of the reticle handler turret gripper 306 gripping the inspection system 302.

[0109] FIG. 8 shows top views 850, 860, and 870 of the reticle stage 310, reticle clamp 312, and associated membrane 852. In some embodiments, membrane 852 may be the target surface to be inspected, for example, by inspection system 302. Typically, membrane 852 contacts the bottom of the reticle and is the area where a barcode (and / or other identification data) is printed. The printing is applied with chrome, MoSi, or other material. When the reticle is clamped via vacuum and subsequently scanned (e.g., for identification purposes), the high contact pressure can initiate molecular-level bonding between the reticle material and the material of clamp 312 and / or membrane 852. When separated, a small portion of the reticle material is pulled off and remains on the surface of membrane 852, necessitating inspection. In practice, the reticle handler turret gripper 306 (not shown in FIG. 8) will lower the inspection system 302 (e.g., the size of a reticle) close to the clamps 312 and / or associated membrane 852 (e.g., into the page). Diagram 860 is an enlarged view of a portion of diagram 850. Diagrams 850 and 860 show the size 854 of a typical reticle held by the clamps 312. Diagram 870 shows the approximate size 872 of an area that may be inspected using the inspection system 302 (e.g., by moving the inspection system 302 around as described above). Size 872 is large enough to include the membrane 852 for inspection.

[0110] 9 shows a view 900 of the turret gripper 306 and feet 600 looking (upward) through the inspection system 302 (e.g., when the body 402 is formed from a transparent material). FIG. 9 also shows close-up views 902 and 904 of the feet 600 positioned relative to the identification feature 412 (by way of example). In some embodiments, the feet 600 of the turret gripper 306 may mate and seal with a continuous surface of the body 402 when the inspection system 302 (e.g., having a reticle shape) is vacuumed to lift and / or move.

[0111] FIG. 10 illustrates a method 1001 for inspecting a portion of a lithographic apparatus. Method 1001 may be performed, for example, using an inspection system. In some embodiments, the inspection system comprises a body, one or more image acquisition devices, one or more light sources, electronics, a power source, one or more identification features, and / or other components. In some embodiments, the inspection system includes and / or is configured to communicate with one or more processors and / or computing systems, as described below (see FIG. 11 ). The steps of method 1001 illustrated below are for illustrative purposes. In some embodiments, method 1001 may be performed with one or more additional steps not described and / or without one or more steps described. Furthermore, the order of steps of the method illustrated in FIG. 10 and described below is not intended to be limiting.

[0112] In some embodiments, one or more portions of method 1001 may be implemented and / or controlled by one or more processing devices (e.g., a digital processor, an analog processor, a digital circuit designed for processing information, an analog circuit designed for processing information, a state machine, and / or other mechanisms for electronically processing information, as described below with respect to FIG. 11). The one or more processing devices may include one or more devices that perform some or all of the steps of method 1001 in response to instructions that are electronically stored on an electronic storage medium. The one or more processing devices may include one or more devices that are configured to be specifically designed through hardware, firmware, and / or software to perform one or more steps of method 1001 (e.g., see description below with respect to FIG. 11). For example, the one or more processing devices may execute software (e.g., ASML TwinScan) that is configured to execute an inspection program that causes one or more steps described herein to be performed.

[0113] At step 1002, the inspection system is inserted into and received by the lithographic apparatus. In some embodiments, the lithographic apparatus is configured for DUV or EUV radiation. In some embodiments, the inspection system comprises a body that is the same size and shape as a reticle. The body typically has a similar or identical shape to a reticle that is engaged and positioned by a tool handler. In some embodiments, the body comprises one or more identification features. In some embodiments, the one or more identification features comprise one or more of a label, a bar code, and an alignment mark. In some embodiments, step 1002 is performed by a tool handler (e.g., the reticle handler robot gripper 307 shown in FIGS. 3A and 3B and described herein) and / or other components of the lithographic apparatus.

[0114] In some embodiments, operation 1002 comprises engaging the inspection system with a second part of a tool handler of the lithographic apparatus and moving it to or near one or more membranes of the lithographic apparatus for inspection. The one or more membranes may be or may include, for example, a chuck membrane associated with a reticle stage reticle clamp. In some embodiments, the second part of the tool handler may be a reticle handler turret gripper and / or other components. The turret gripper is configured to grip the body at one or more surfaces and / or edges of the body, move the body to a position adjacent to the membrane of the lithographic apparatus, and adjust the position of the body (e.g., to obtain a clear image). In some embodiments, the reticle handler turret gripper is the same as or similar to turret gripper 306 (shown in FIGS. 3A and 3B and described herein).

[0115] At step 1004, the one or more films are illuminated. Step 1004 comprises illuminating a film of a lithographic device imaged by the one or more image capture devices using one or more light sources associated with the one or more image capture devices and coupled to the body. In some embodiments, the one or more light sources comprise one or more light emitting diodes (LEDs). In some embodiments, step 1004 is performed by one or more light sources as described above (e.g., light source 406 shown in FIG. 4 and described herein).

[0116] At step 1006, the inspection system is used to acquire one or more images of the film. Step 1006 includes acquiring one or more images of a portion of the lithographic apparatus using one or more image acquisition devices coupled to the body. The one or more image acquisition devices are configured to acquire one or more images of a portion of the lithographic apparatus when the body is positioned by the tool handler. In some embodiments, the one or more image acquisition devices comprise one or more optical cameras. In some embodiments, step 1006 is performed by one or more image acquisition devices as described above (e.g., image acquisition device 404 shown in FIG. 4 and described herein). In some embodiments, step 1006 comprises receiving and storing one or more images from the one or more image acquisition devices using electronics coupled to the body (e.g., electronics 408 shown in FIG. 4) and / or wirelessly communicating information to and from the one or more image acquisition devices using the electronics. In some embodiments, the one or more image acquisition devices, one or more light sources, and / or associated electronics are powered by a power source coupled to the body (e.g., power source 410 shown in FIG. 4).

[0117] At step 1008, an inspection is performed based on the images and / or other information. In some embodiments, step 1008 is performed by one or more processors described herein (e.g., processors 1104, 1105 shown in FIG. 11 , electronics 408 shown in FIG. 4 , and / or other components. Step 1008 comprises receiving one or more images from one or more image acquisition devices and facilitating semi-automated or automated inspection of the film in the lithographic apparatus based on the one or more images.

[0118] In some embodiments, facilitating the semi-automated inspection comprises displaying one or more images to a user using a user interface and receiving input and / or selection of control commands from a user via the user interface. The control commands comprise instructions to move the body and one or more image acquisition devices based on a region of interest of the film of the lithographic apparatus, instructions to adjust the zoom and / or focus of the one or more image acquisition devices, instructions to adjust illumination from one or more light sources associated with the one or more image acquisition devices, and / or instructions to acquire an updated image using the adjusted zoom, focus, and / or illumination. In some embodiments, operation 1008 comprises displaying the updated image to a user using a user interface and enabling the user to determine the presence of contamination in the region of interest based on the updated image. In some embodiments, displaying the one or more images and / or the updated image to a user comprises a live stream.

[0119] In some embodiments, facilitating the automated inspection comprises determining a region of interest of the film of the lithographic apparatus based on the one or more images, controlling a tool handler to move the body and the one or more image acquisition devices based on the region of interest, adjusting a zoom and / or focus of the one or more image acquisition devices based on the one or more images, adjusting illumination from one or more light sources associated with the one or more image acquisition devices based on the one or more images, causing the one or more image acquisition devices to acquire updated images using the adjusted zoom, focus, and / or illumination, determining a presence of contamination in the region of interest based on the updated images, and / or other steps. In some embodiments, the one or more processors are configured to assist the automated inspection based on the trained machine learning algorithm.

[0120] In some embodiments, the trained machine learning algorithm comprises a neural network having an input layer, an output layer, and one or more hidden layers. The trained machine learning algorithm is configured to receive one or more images as input and output corresponding control commands. The corresponding control commands relate to determining an area of ​​interest, controlling a tool handler to move the body and one or more image capture devices, adjusting zoom and / or focus, adjusting lighting, causing one or more image capture devices to capture updated images, determining the presence of contamination, and / or other processes. The trained machine learning algorithm is trained based on previously acquired images of parts of the lithographic apparatus with or without contamination, and / or other information. The previously acquired images may be labeled with the area of ​​interest, the location of the body and / or image capture device relative to the area of ​​interest, focus of the image capture device, lighting, an indication of whether contamination is present, and / or other information. The performance of the lithographic apparatus is related to the contamination identified in the images, and correlations between the performance data of the lithographic apparatus and the image inspection data are also used to configure the machine learning algorithm.

[0121] 11 is a block diagram illustrating a computer system 1100 that can assist in implementing a method, flow, or system disclosed herein. The computer system 1100 includes a bus 1102 or other communication mechanism for communicating information and a processor 1104 (or multiple processors 1104 and 1105) coupled to the bus 1102 for processing information. The computer system 1100 also includes a main memory 1106, such as a random access memory (RAM) or other dynamic storage device, coupled to the bus 1102 for storing information and instructions executed by the processor 1104. The main memory 1106 may be used to store temporary variables or other intermediate information during execution of instructions to be executed by the processor 1104. The computer system 1100 further includes a read only memory (ROM) 1108 or other static storage device coupled to the bus 1102 for storing static information and instructions for the processor 1104. A storage device 1110, such as a magnetic disk or optical disk, is provided and coupled to the bus 1102 for storing information and instructions.

[0122] The computer system 1100 may be coupled via a bus 1102 to a display 1112, such as a cathode ray tube (CRT) or flat panel or touch panel display, for displaying information to a computer user. An input device 1114, including alphanumeric and other keys, is coupled to the bus 1102 for communicating information and selecting commands with the processor 1104. Another type of user input device is a cursor control 1116, such as a mouse, trackball, cursor direction keys, etc., for communicating information and selecting commands with the processor 1104 and for controlling cursor movement on the display 1112. This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), allowing the device to determine a position in a plane. A touch panel (screen) display may also be used as an input device.

[0123] According to one embodiment, portions of one or more of the flows and / or methods described herein may be performed by computer system 1100 in response to processor 1104 executing one or more sequences of one or more instructions contained in main memory 1106. Such instructions may be read into main memory 1106 from another computer-readable medium, such as storage device 1110. Execution of the sequences of instructions contained in main memory 1106 causes processor 1104 to perform the flows and / or process steps described herein. One or more processors in a multi-processing configuration may be used to execute the sequences of instructions contained in main memory 1106. In alternative embodiments, hardwired circuitry may be used in place of or in combination with software instructions. Thus, the description set forth herein is not limited to any specific combination of hardware circuitry and software.

[0124] The terms "computer-readable medium" or "machine-readable medium" as used herein refer to any medium that participates in providing instructions to the processor 1104 for execution. Such media may take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as the storage device 1110. Volatile media include dynamic memory, such as the main memory 1106. Transmission media include coaxial cables, copper wire, and optical fibers, including the wires that comprise the bus 1102. Transmission media can also take the form of acoustic or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, a hard disk, a magnetic tape, any other magnetic medium, a CD-ROM, a DVD, any other optical medium, punch cards, paper tape, other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described below, or any other medium from which a computer can read.

[0125] Various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to the processor 1104 for execution. For example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into a dynamic memory and send the instructions over a telephone line using a modem. A modem local to the computer system 1100 can receive the data on the telephone line and use an infrared transmitter to convert the data to an infrared signal. An infrared detector coupled to the bus 1102 can receive the data carried in the infrared signal and place the data on the bus 1102. The bus 1102 carries the data to the main memory 1106, from which the processor 1104 retrieves and executes the instructions. The instructions received by the main memory 1106 may optionally be stored on a storage device 1110 before or after execution by the processor 1104.

[0126] The computer system 1100 may also include a communication interface 1118 coupled to the bus 1102. The communication interface 1118 provides a two-way data communication connection to a network link 1120 that is connected to a local network 1122. For example, the communication interface 1118 may be an Integrated Services Digital Network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, the communication interface 1118 may be a LAN card to provide a data communication connection to a compatible local area network (LAN). A wireless link may also be implemented. In any such implementation, the communication interface 1118 sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

[0127] The network link 1120 typically provides data communication through one or more networks to other data devices. For example, the network link 1120 may provide a connection through a local network 1122 to a host computer 1124 or to data equipment operated by an Internet Service Provider (ISP) 1126. The ISP 1126 provides data communication services through a world wide packet data communication network now commonly referred to as the "Internet" 1128. Both the local network 1122 and the Internet 1128 use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on the network link 1120 and through the communication interface 1118, which carry the digital data to and from the computer system 1100, are exemplary forms of carrier waves transporting the information.

[0128] The computer system 1100 can send messages and receive data, including program code, through the network, network link 1120 and communication interface 1118. In the Internet example, a server 1130 may transmit a requested code for an application program through the Internet 1128, the ISP 1126, the local network 1122 and communication interface 1118. One such downloaded application may, for example, provide all or a portion of the methods described herein. The received code may be executed by the processor 1104 upon receipt, and / or stored in the storage device 1110, or other non-volatile storage for later execution. In this manner, the computer system 1100 may obtain the application code in the form of a carrier wave.

[0129] FIG. 12 shows a schematic diagram of an exemplary lithographic projection apparatus LA, which is similar and / or identical to the apparatus shown in FIG. 1, FIG. 3A and / or FIG. 3B and can be used in combination with the techniques described herein. The apparatus LA may generally represent a DUV apparatus, for example with a twin scan setup (this example is not intended to be limiting). The apparatus comprises an illumination system IL configured to condition a beam B of radiation. In this example, the illumination system also comprises a radiation source SO. The apparatus comprises a first object table (e.g. patterning device table) MT comprising a patterning device holder for holding a patterning device MA (e.g. a reticle). This is connected to a first positioning device for accurately positioning the patterning device with respect to the item PS. The apparatus comprises a second object table (substrate table) WT comprising a substrate holder for holding a substrate W (e.g. a resist-coated silicon wafer). This is connected to a second positioning device for accurately positioning the substrate with respect to the item PS. The apparatus comprises a projection system ("lens") PS (eg a refractive, reflective or catadioptric system) that images an irradiated portion of the patterning device MA onto a target portion C (eg comprising one or more dies) of the substrate W.

[0130] As depicted, the apparatus LA is of a transmissive type (i.e. has a transmissive patterning device), but in general it may be of a reflective type, for example (having a reflective patterning device). The apparatus may employ other types of patterning device than a conventional mask, and may include, by way of example, a programmable mirror array or an LCD matrix.

[0131] A radiation source SO (e.g. a mercury lamp or excimer laser, LPP (Laser Produced Plasma) EUV source) generates a beam of radiation. This beam is fed into an illumination system (illuminator) IL, for example after passing conditioning means, such as a beam expander, or directly. The illuminator IL may comprise conditioning means for setting the outer and / or inner radial extent (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution of the beam. Furthermore, the illuminator IL will typically comprise various other components, such as an integrator and a condenser. In this way, the beam B incident on the patterning device MA has a desired uniformity and intensity distribution in its cross-section.

[0132] It should be noted with regard to Figure 12 that the source SO may be within the housing of the lithographic projection apparatus (for example when the source SO is a mercury lamp), but it may also be remote from the lithographic projection apparatus and the radiation beam that it generates may be directed into the apparatus (for example with the aid of suitable directing mirrors). The latter scenario is typical when the source SO is an excimer laser (for example based on a KrF, ArF or F2 laser).

[0133] The beam B then traverses the patterning device MA, which is held on a patterning device table MT. Having passed the patterning device MA, the beam B passes through a lens PL, which focuses the beam B onto a target portion C of the substrate W. With the aid of the second positioning device (and the interferometric measurement means), the substrate table WT can be precisely moved, e.g. to position a different target portion C in the path of the beam. Similarly, the first positioning means can be used to precisely position the patterning device MA with respect to the path of the beam B, e.g. after mechanical retrieval of the patterning device MA from a patterning device library or during a scan. Typically, movements of the object table MT, WT are realised with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which are not explicitly shown. However, in the case of a stepper (as opposed to a step-and-scan tool) the patterning device table MT may be connected to a short-stroke actuator only or may be fixed.

[0134] As mentioned above, the LA can be used in two different modes. In step mode, the patterning device table MT is kept essentially stationary and the entire patterning device image is projected onto the target portion C in one go (i.e. in one "flash"). The substrate table WT is then moved in the x and / or y direction so that a different target portion C can be exposed with the beam. In scan mode, essentially the same scenario applies, with the difference that a particular target portion C is not exposed in one "flash". Instead, the patterning device table MT is movable in a particular direction (the so-called "scan direction", e.g. the y direction) with a speed v, and the projection beam B is scanned over the patterning device image. Simultaneously, the substrate table WT is simultaneously moved in the same or opposite direction with a speed V = Mv, where M is the magnification of the lens PL (typically M = 1 / 4 or 1 / 5). In this way, a relatively large target portion C can be exposed, without sacrificing resolution.

[0135] Various embodiments of the systems and methods of the present disclosure are disclosed in the following numbered paragraph listing. (Item 1) A system for inspecting a part of a lithographic apparatus, comprising: a body configured to be inserted into the lithographic apparatus, engaged by a tool handler of the lithographic apparatus, and positioned by the tool handler to inspect the part of the lithographic apparatus; and one or more image acquisition devices coupled to the body and configured to acquire one or more images of the part of the lithographic apparatus when the body is positioned by the tool handler. (Item 2) The system described in item 1, wherein the body has a shape similar or identical to a reticle that is engaged and positioned by the tool handler. (Item 3) A system described in any of the above items, wherein the portion of the lithographic apparatus comprises one or more film surfaces of the lithographic apparatus. (Item 4) A system described in any of the above items, wherein the portion of the lithographic apparatus comprises a chuck membrane associated with a reticle stage reticle clamp. (Item 5) A system described in any of the above items, wherein the body has a rectangular shape, the tool handler comprises a reticle handler and a turret gripper, the reticle handler configured to move the body from a load port of the lithographic apparatus to the turret gripper, and the turret gripper configured to grasp the body by one or more edges of the body, move the body to a position adjacent to the portion of the lithographic apparatus, and adjust the position of the body. (Item 6) A system described in any of the above items, wherein the one or more image acquisition devices comprise one or more optical cameras. (Item 7) A system described in any of the above items, further comprising one or more light sources associated with the one or more image acquisition devices and coupled to the body, the one or more light sources configured to illuminate the portion of the lithographic apparatus that is imaged by the one or more image acquisition devices. (Item 8) A system described in any of the above items, wherein the one or more light sources comprise one or more light emitting diodes (LEDs). (Item 9) A system described in any of the above items, further comprising electronic equipment coupled to the main body, the electronic equipment configured to receive and store the one or more images from the one or more image acquisition devices, and / or configured to wirelessly communicate information between the one or more image acquisition devices. (Item 10) A system described in any of the above items, further comprising a power source coupled to the main body, the power source configured to supply power to the one or more image capture devices, the one or more light sources, and / or associated electronics. (Item 11) A system described in any of the above items, wherein the body is provided with one or more identification features. (Item 12) The system described in any of the above items, wherein the one or more identification features comprise one or more of a label, a barcode, and an alignment mark. (Item 13) A system described in any of the above items, further comprising one or more processors, the one or more processors configured with machine-readable instructions to receive the one or more images from the one or more image acquisition devices, assist in semi-automatic or automatic inspection of the portion of the lithographic apparatus based on the one or more images, and communicate data to one or more external computing devices. (Item 14) The system described in any of the above items, wherein the one or more processors are configured to support semi-automatic inspection, and supporting semi-automatic inspection comprises displaying the one or more images to a user using a user interface, and receiving input and / or selection of control commands from the user via the user interface, the control commands comprising instructions for moving the body and the one or more image acquisition devices based on a region of interest of the portion of the lithographic apparatus, instructions for adjusting the focus of the one or more image acquisition devices, instructions for adjusting illumination from the one or more light sources associated with the one or more image acquisition devices, and / or instructions for acquiring an updated image using the adjusted focus and / or illumination, and displaying the updated image to the user using the user interface and enabling the user to determine the presence of contamination in the region of interest based on the updated image. (Item 15) A system described in any of the above items, wherein displaying the one or more images and / or the updated image to a user comprises a live stream. (Item 16) The system described in any of the above items, wherein the one or more processors are configured to assist in automated inspection, and assisting in automated inspection comprises determining a region of interest of the portion of the lithographic apparatus based on the one or more images, controlling the tool handler to move the body and the one or more image acquisition devices based on the region of interest, adjusting focus of the one or more image acquisition devices based on the one or more images, adjusting illumination from one or more light sources associated with the one or more image acquisition devices based on the one or more images, causing the one or more image acquisition devices to acquire updated images using the adjusted focus and / or illumination, and / or determining the presence of contamination in the region of interest based on the updated images. (Item 17) The system described in any of the above items, wherein the one or more processors are configured to assist the automated inspection based on a trained machine learning algorithm, the trained machine learning algorithm configured to receive the one or more images as input and output corresponding control commands, the corresponding control commands related to determining the area of ​​interest, controlling the tool handler to move the body and the one or more image acquisition devices, adjusting the focus, adjusting the lighting, causing the one or more image acquisition devices to acquire updated images, and / or determining the presence of contamination. (Item 18) A system described in any of the above items, wherein the trained machine learning algorithm is trained based on previously acquired images of the part of the lithographic apparatus with or without contamination, the previously acquired images being labeled with an area of ​​interest, the position of the body and / or imaging device relative to the area of ​​interest, the focus of the imaging device, the lighting, and / or an indication of whether contamination is present, the performance of the lithographic apparatus being related to the contamination identified in the images, and correlation between the lithographic apparatus performance data and image inspection data being used to configure the machine learning algorithm. (Item 19) A system described in any of the above items, wherein the trained machine learning algorithm comprises a neural network having an input layer, an output layer, and one or more hidden layers. (Item 20) A system described in any of the above items, wherein the lithographic apparatus is configured for deep ultraviolet (DUV) radiation or extreme ultraviolet (EUV) radiation. (Item 21) A computer program product comprising a non-transitory computer-readable medium having instructions recorded thereon, the instructions, when executed by one or more processors of a computer, causing an operation comprising receiving one or more images from one or more image acquisition devices included in an inspection system for inspecting a portion of a lithographic apparatus, the inspection system comprising a body configured to be inserted into the lithographic apparatus and engaged by a tool handler of the lithographic apparatus and positioned by the tool handler to inspect the portion of the lithographic apparatus, and one or more image acquisition devices coupled to the body and configured to acquire one or more images of the portion of the lithographic apparatus when the body is positioned by the tool handler, and causing an operation comprising assisting inspection of the portion of the lithographic apparatus based on the one or more images. (Item 22) The medium described in Item 21, wherein the one or more processors are configured to support semi-automatic inspection, and supporting semi-automatic inspection comprises displaying the one or more images to a user using a user interface, and receiving input and / or selection of control commands from the user via the user interface, the control commands comprising instructions for moving the body and the one or more image acquisition devices based on a region of interest of the portion of the lithographic apparatus, instructions for adjusting focus of the one or more image acquisition devices, instructions for adjusting illumination from one or more light sources associated with the one or more image acquisition devices, and / or instructions for acquiring an updated image using the adjusted focus and / or illumination, and displaying the updated image to a user using the user interface and enabling the user to determine the presence of contamination in the region of interest based on the updated image. (Item 23) The medium described in any of the above items, wherein displaying the one or more images and / or the updated image to a user comprises a live stream. (Item 24) The medium described in any of the above items, wherein the one or more processors are configured to assist in automated inspection, where assisting in automated inspection comprises determining a region of interest of the portion of the lithographic apparatus based on the one or more images, controlling the tool handler to move the body and the one or more image acquisition devices based on the region of interest, adjusting focus of the one or more image acquisition devices based on the one or more images, adjusting illumination from one or more light sources associated with the one or more image acquisition devices based on the one or more images, causing the one or more image acquisition devices to acquire updated images using the adjusted focus and / or illumination, and / or determining the presence of contamination in the region of interest based on the updated images. (Item 25) The media described in any of the above items, wherein the one or more processors are configured to assist in automated inspection based on a trained machine learning algorithm, the trained machine learning algorithm configured to receive the one or more images as input and output corresponding control commands, the corresponding control commands related to determining an area of ​​interest, controlling the tool handler to move the body and the one or more image acquisition devices, adjusting the focus, adjusting the lighting, causing the one or more image acquisition devices to acquire updated images, and / or determining the presence of the contamination. (Item 26) A medium described in any of the above items, wherein the trained machine learning algorithm is trained based on previously acquired images of the portion of the lithographic apparatus with or without contamination, and the previously acquired images are labeled with an area of ​​interest, the location of the body and / or imaging device relative to the area of ​​interest, the focus of the imaging device, the lighting, and / or an indication of whether contamination is present. (Item 27) The medium described in any of the above items, wherein the body has a shape similar or identical to a reticle that is engaged and positioned by the tool handler. (Item 28) The medium described in any of the above items, wherein the portion of the lithographic apparatus comprises one or more chuck membrane surfaces associated with a reticle stage clamp of the lithographic apparatus. (Item 29) The medium described in any of the above items, wherein the tool handler comprises a reticle handler and a turret gripper, the reticle handler configured to move the body from a load port of the lithographic apparatus to the turret gripper, and the turret gripper configured to move the body to a position adjacent to the portion of the lithographic apparatus and adjust the position of the body. (Item 30) The medium described in any of the above items, wherein the inspection system further comprises one or more light sources associated with the one or more image acquisition devices and coupled to the body, the one or more light sources configured to illuminate the portion of the lithographic apparatus imaged by the one or more image acquisition devices, the inspection system further comprises electronics coupled to the body, the electronics configured to receive and store the one or more images from the one or more image acquisition devices, and / or configured to wirelessly communicate information between the one or more image acquisition devices, the inspection system further comprises a power source coupled to the body, the power source configured to provide power to the one or more image acquisition devices, the one or more light sources, and / or the electronics, and / or the inspection system further comprises one or more identification features, the one or more identification features comprising one or both of a barcode and an alignment mark. (Item 31) A method for inspecting a part of a lithographic apparatus, the method comprising receiving a body to be inserted into the lithographic apparatus, the body configured to be engaged by a tool handler of the lithographic apparatus and positioned by the tool handler to inspect the part of the lithographic apparatus, the method comprising acquiring one or more images of the part of the lithographic apparatus using the one or more image acquisition devices coupled to the body, the one or more image acquisition devices configured to acquire one or more images of the part of the lithographic apparatus when the body is positioned by the tool handler. (Item 32) The method of item 31, wherein the body has a shape similar or identical to a reticle that is engaged and positioned by the tool handler. (Item 33) A method according to any of the above items, wherein the portion of the lithographic apparatus comprises one or more film surfaces of the lithographic apparatus. (Item 34) A method according to any of the above items, wherein the portion of the lithographic apparatus comprises a chuck membrane associated with a reticle stage reticle clamp. (Item 35) A method according to any of the above items, wherein the body has a rectangular shape, the tool handler comprises a reticle handler and a turret gripper, the reticle handler configured to move the body from a load port of the lithographic apparatus to the turret gripper, and the turret gripper configured to grasp the body by one or more edges of the body, move the body to a position adjacent to the portion of the lithographic apparatus, and adjust the position of the body. (Item 36) A method according to any of the above items, wherein the one or more image capture devices comprise one or more optical cameras. (Item 37) A method according to any of the above items, further comprising illuminating the portion of the lithographic apparatus imaged by the one or more image acquisition devices using one or more light sources associated with the one or more image acquisition devices and coupled to the body. (Item 38) The method of any of the above items, wherein the one or more light sources comprise one or more light emitting diodes (LEDs). (Item 39) A method according to any of the above items, further comprising receiving and storing the one or more images from the one or more image capture devices using electronics coupled to the main body, and / or wirelessly communicating information between the one or more image capture devices using the electronics. (Item 40) A method according to any of the above items, further comprising powering the one or more image capture devices, the one or more light sources, and / or associated electronics using a power source coupled to the main body. (Item 41) A method according to any of the above items, wherein the body is provided with one or more identification features. (Item 42) A method according to any of the above items, wherein the one or more identification features comprise one or more of a label, a bar code, and an alignment mark. (Item 43) A method according to any of the above items, further comprising: receiving, using one or more processors, the one or more images from the one or more image acquisition devices; using the one or more processors to support semi-automatic or automatic inspection of the portion of the lithographic apparatus based on the one or more images; and using the one or more processors to communicate data to one or more external computing devices. (Item 44) A method according to any of the above items, wherein the one or more processors are configured to support semi-automatic inspection, wherein supporting semi-automatic inspection comprises displaying the one or more images to a user using a user interface, and receiving input and / or selection of control commands from the user via the user interface, the control commands comprising instructions for moving the body and the one or more image acquisition devices based on a region of interest of the portion of the lithographic apparatus, instructions for adjusting the focus of the one or more image acquisition devices, instructions for adjusting illumination from the one or more light sources associated with the one or more image acquisition devices, and / or instructions for acquiring an updated image using the adjusted focus and / or illumination, and displaying the updated image to the user using the user interface and enabling the user to determine the presence of contamination in the region of interest based on the updated image. (Item 45) A method according to any of the above items, wherein displaying the one or more images and / or the updated image to a user comprises a live stream. (Item 46) A method according to any of the above items, wherein the one or more processors are configured to assist in automated inspection, and assisting in automated inspection comprises determining a region of interest of the portion of the lithographic apparatus based on the one or more images, controlling the tool handler to move the body and the one or more image acquisition devices based on the region of interest, adjusting a focus of the one or more image acquisition devices based on the one or more images, adjusting illumination from one or more light sources associated with the one or more image acquisition devices based on the one or more images, causing the one or more image acquisition devices to acquire updated images using the adjusted focus and / or illumination, and / or determining the presence of contamination in the region of interest based on the updated images. (Item 47) A method according to any of the above items, wherein the one or more processors are configured to assist the automated inspection based on a trained machine learning algorithm, the trained machine learning algorithm configured to receive the one or more images as input and output corresponding control commands, the corresponding control commands related to determining the area of ​​interest, controlling the tool handler to move the body and the one or more image acquisition devices, adjusting the focus, adjusting the lighting, causing the one or more image acquisition devices to acquire updated images, and / or determining the presence of contamination. (Item 48) A method according to any of the above items, wherein the trained machine learning algorithm is trained based on previously acquired images of the part of the lithographic apparatus with or without contamination, the previously acquired images being labelled with an area of ​​interest, the position of the body and / or imaging device relative to the area of ​​interest, the focus of the imaging device, the lighting, and / or an indication of whether contamination is present, the performance of the lithographic apparatus being related to the contamination identified in the images, and correlation between the lithographic apparatus performance data and image inspection data being used to configure the machine learning algorithm. (Item 49) A method according to any of the above items, wherein the trained machine learning algorithm comprises a neural network having an input layer, an output layer, and one or more hidden layers. (Item 50) A method according to any of the above items, wherein the lithographic apparatus is configured for deep ultraviolet (DUV) radiation or extreme ultraviolet (EUV) radiation.

[0136] The concepts disclosed herein may be associated with any general imaging system that images features smaller than a wavelength, and may be particularly useful for new imaging technologies capable of producing ever-shorter wavelengths. New technologies already in use include EUV (extreme ultraviolet), DUV lithography that can produce wavelengths of 193 nm using ArF lasers, and even DUV lithography that can produce wavelengths of 157 nm using fluorine lasers. EUV lithography can also produce wavelengths in this range by using a synchrotron or by bombarding a material (either a solid or a plasma) with high energy electrons to produce photons in the range of 20-5 nm.

[0137] Although the concepts disclosed herein may be used in wafer fabrication on substrates such as silicon wafers, it will be understood that the disclosed concepts may be used in any type of fabrication system, such as systems used for fabrication on substrates other than silicon wafers. Additionally, combinations and subcombinations of the disclosed elements may constitute separate embodiments. For example, an inspection system and associated software may constitute separate embodiments and / or their functionality may be used together in the same embodiment.

[0138] The above description is intended to be illustrative and not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made as described without departing from the scope of the claims set forth below.

Claims

1. 1. A system for inspecting a part of a lithographic apparatus, comprising: a body configured to be inserted into the lithographic apparatus, engaged by a tool handler of the lithographic apparatus, and positioned by the tool handler to inspect the portion of the lithographic apparatus; one or more image capture devices coupled to the body and configured to capture one or more images of the portion of the lithographic apparatus in response to the tool handler positioning the body.

2. the lithographic apparatus is configured for deep ultraviolet (DUV) radiation or extreme ultraviolet (EUV) radiation; the body has a shape similar or identical to a reticle that is engaged and positioned by the tool handler; the body comprises one or more identification features comprising one or more of a label, a bar code, and an alignment mark; the portion of the lithographic apparatus comprises one or more membrane surfaces of the lithographic apparatus, or a chuck membrane associated with a reticle stage reticle clamp; The system of claim 1 , wherein the one or more image capture devices comprise one or more optical cameras.

3. The body has a rectangular shape, the tool handler comprises a reticle handler and a turret gripper; the reticle handler is configured to move the body from a load port of the lithographic apparatus to the turret gripper; The system of claim 1 , wherein the turret gripper is configured to grip the body by one or more edges of the body, move the body to a position adjacent the portion of the lithographic apparatus, and adjust a position of the body.

4. the system further comprising one or more light sources associated with the one or more image capture devices and coupled to the body, the one or more light sources configured to illuminate the portion of the lithographic apparatus imaged by the one or more image capture devices; the system further comprising electronics coupled to the body, the electronics configured to receive and store the one or more images from the one or more image capture devices and / or to wirelessly communicate information to and from the one or more image capture devices; The system further comprises a power source coupled to the body, the power source configured to provide power to the one or more image capture devices, the one or more light sources, and / or associated electronics; The system of claim 1 , wherein the one or more light sources comprise one or more light emitting diodes (LEDs).

5. and one or more processors, the one or more processors being configured with machine-readable instructions to: receiving the one or more images from the one or more image capture devices; supporting semi-automated or automated inspection of the portion of the lithographic apparatus based on the one or more images; The system of claim 1 configured to communicate data to one or more external computing devices.

6. The one or more processors are configured to support semi-automated inspection, and supporting semi-automated inspection includes: displaying the one or more images to a user using a user interface, wherein causing the one or more images and / or updated images to be displayed to the user comprises a live stream; receiving input and / or selection of control commands from the user via the user interface, the control commands comprising instructions to move the body and the one or more image capture devices based on a region of interest of the portion of the lithographic apparatus, instructions to adjust focus of the one or more image capture devices, instructions to adjust illumination from the one or more light sources associated with the one or more image capture devices, and / or instructions to capture an updated image using the adjusted focus and / or illumination; 6. The system of claim 5, further comprising displaying the updated image to the user using the user interface to enable the user to determine the presence of contamination in the region of interest based on the updated image.

7. The one or more processors are configured to support automated testing, where supporting automated testing includes: determining a region of interest of the portion of the lithographic apparatus based on the one or more images; controlling the tool handler to move the body and the one or more image capture devices based on the region of interest; adjusting a focus of the one or more image capture devices based on the one or more images; adjusting illumination from one or more light sources associated with the one or more image capture devices based on the one or more images; causing the one or more image capture devices to capture updated images using the adjusted focus and / or illumination; and / or The system of claim 5 , further comprising: determining a presence of contamination in the region of interest based on the updated image.

8. the one or more processors are configured to assist in the automated inspection based on a trained machine learning algorithm, the trained machine learning algorithm configured to receive the one or more images as input and to output corresponding control commands, the corresponding control commands related to determining the region of interest, controlling the tool handler to move the body and the one or more image capture devices, adjusting the focus, adjusting the lighting, causing the one or more image capture devices to capture updated images, and / or determining the presence of the contamination; 8. The system of claim 7, wherein the trained machine learning algorithm comprises a neural network having an input layer, an output layer, and one or more hidden layers.

9. the trained machine learning algorithm is trained based on previously acquired images of the portion of the lithographic apparatus with or without contamination, the previously acquired images being labeled with an area of ​​interest, a location of the body and / or an imaging device relative to the area of ​​interest, imaging device focus, illumination, and / or an indication of whether contamination is present; performance of the lithographic apparatus being related to the contamination identified in the images; and correlations between the lithographic apparatus performance data and image inspection data being used to configure the machine learning algorithm; 10. The system of claim 8, wherein the trained machine learning algorithm comprises a neural network having an input layer, an output layer, and one or more hidden layers.

10. 1. A computer program product comprising a non-transitory computer-readable medium having instructions recorded thereon, the instructions, when executed by one or more processors of a computer, causing an operation comprising receiving one or more images from one or more image acquisition devices included in an inspection system for inspecting a portion of a lithographic apparatus, the inspection system comprising: a body configured to be inserted into the lithographic apparatus, engaged by a tool handler of the lithographic apparatus and positioned by the tool handler to inspect the portion of the lithographic apparatus; and one or more image acquisition devices coupled to the body and configured to acquire one or more images of the portion of the lithographic apparatus in response to the tool handler positioning the body; 36. A computer program product, the computer program product causing operations comprising facilitating inspection of the portion of the lithographic apparatus based on the one or more images.

11. The one or more processors are configured to support semi-automated inspection, and supporting semi-automated inspection includes: displaying the one or more images to a user using a user interface, wherein displaying the one or more images and / or updated images to the user comprises a live stream; receiving input and / or selection of control commands from the user via the user interface, the control commands comprising instructions to move the body and the one or more image capture devices based on a region of interest of the portion of the lithographic apparatus, instructions to adjust focus of the one or more image capture devices, instructions to adjust illumination from one or more light sources associated with the one or more image capture devices, and / or instructions to capture an updated image using the adjusted focus and / or illumination; 11. The computer program product of claim 10, further comprising: displaying the updated image to the user using the user interface to enable the user to determine the presence of contamination in the region of interest based on the updated image.

12. The one or more processors are configured to support automated testing, where supporting automated testing includes: determining a region of interest of the portion of the lithographic apparatus based on the one or more images; controlling the tool handler to move the body and the one or more image capture devices based on the region of interest; adjusting a focus of the one or more image capture devices based on the one or more images; adjusting illumination from one or more light sources associated with the one or more image capture devices based on the one or more images; causing the one or more image capture devices to capture updated images using the adjusted focus and / or illumination; and / or 11. The computer program product of claim 10, further comprising: determining a presence of contamination in the region of interest based on the updated image.

13. 13. The computer program product of claim 12, wherein the one or more processors are configured to assist in the automated inspection based on a trained machine learning algorithm, the trained machine learning algorithm configured to receive the one or more images as input and to output corresponding control commands, the corresponding control commands related to determining the region of interest, controlling a tool handler to move the body and the one or more image capture devices, adjusting the focus, adjusting the lighting, causing the one or more image capture devices to capture updated images, and / or determining the presence of the contamination.

14. 14. The computer program product of claim 13, wherein the trained machine learning algorithm is trained based on previously acquired images of the portion of the lithographic apparatus with or without contamination, the previously acquired images being labeled with an area of ​​interest, a location of the body and / or an imaging device relative to the area of ​​interest, imaging device focus, lighting, and / or an indication of whether contamination is present.

15. 1. A method for inspecting a part of a lithographic apparatus, comprising the steps of: receiving a body configured to be inserted into the lithographic apparatus, engaged by a tool handler of the lithographic apparatus, and positioned by the tool handler to inspect the portion of the lithographic apparatus; acquiring one or more images of the portion of the lithographic apparatus using one or more image acquisition devices coupled to the body and configured to acquire one or more images of the portion of the lithographic apparatus in response to the tool handler positioning the body.

Images