Modular conditioning apparatus

Abstract

A modular conditioning apparatus may include a core having a first surface polished to optical contact quality. The modular conditioning apparatus may include a conditioning sheet having a grinding surface and a second surface opposite the grinding surface. The second surface is polished to the optical contact quality for optically contacting the first surface such that that the conditioning sheet is removably bonded to the core.

Description

MODULAR CONDITIONING APPARATUSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63 / 742,585 which was filed on 07 January 2025, and which is incorporated herein in its entirety by reference.TECHNICAL FIELD

[0002] The description herein relates generally to conditioning of a support structure for a substrate such as used in the manufacturing of semiconductor devices. More particularly, the disclosure includes apparatuses and methods for improved support structure conditioning devices.BACKGROUND

[0003] A lithographic projection apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device (e.g., a mask) may contain or provide a pattern corresponding to an individual layer of the IC (“design layout”), and this pattern can be transferred onto a target portion (e.g. comprising one or more dies) on a substrate (e.g., silicon wafer) that has been coated with a layer of radiation-sensitive material (“resist”), by methods such as irradiating the target portion through the pattern on the patterning device. In general, a single substrate contains a plurality of adjacent target portions to which the pattern is transferred successively by the lithographic projection apparatus, one target portion at a time. In one type of lithographic projection apparatuses, the pattern on the entire patterning device is transferred onto one target portion in one go; such an apparatus may also be referred to as a stepper. In an alternative apparatus, a step-and-scan apparatus can cause a projection beam to scan over the patterning device in a given reference direction (the “scanning” direction) while synchronously moving the substrate parallel or anti-parallel to this reference direction. Different portions of the pattern on the patterning device are transferred to one target portion progressively. Since, in general, the lithographic projection apparatus will have a reduction ratio M (e.g., 4), the speed F at which the substrate is moved will be 1 / M times that at which the projection beam scans the patterning device. More information with regard to lithographic devices can be found in, for example, U.S. Patent No. 6,046,792, the contents of which are incorporated herein by reference.

[0004] Prior to transferring the pattern from the patterning device to the substrate, the substrate may undergo various procedures, such as priming, resist coating and a soft bake. After exposure, the substrate may be subjected to other procedures (“post-exposure procedures”), such as a post-exposure bake (PEB), development, a hard bake and measurement / inspection of the transferred pattern. This array of procedures is used as a basis to make an individual layer of a device, e.g., an IC. The substrate may then undergo various processes such as etching, ion-implantation (doping), metallization, oxidation, chemo-mechanical polishing, etc., all intended to finish the individual layer of the device. If several layers are required in the device, then the whole procedure, or a variant thereof, is repeated foreach layer. Eventually, a device will be present in each target portion on the substrate. These devices are then separated from one another by a technique such as dicing or sawing, whence the individual devices can be mounted on a carrier, connected to pins, etc.

[0005] Thus, manufacturing devices, such as semiconductor devices, typically involves processing a substrate (e.g., a semiconductor wafer) using a number of fabrication processes to form various features and multiple layers of the devices. Such layers and features are typically manufactured and processed using, e.g., deposition, lithography, etch, chemical-mechanical polishing, and ion implantation. Multiple devices may be fabricated on a plurality of dies on a substrate and then separated into individual devices. This device manufacturing process may be considered a patterning process. A patterning process involves a patterning step, such as optical and / or nanoimprint lithography using a patterning device in a lithographic apparatus, to transfer a pattern on the patterning device to a substrate and typically, but optionally, involves one or more related pattern processing steps, such as resist development by a development apparatus, baking of the substrate using a bake tool, etching using the pattern using an etch apparatus, etc.

[0006] As noted, lithography is a central step in the manufacturing of device such as ICs, where patterns formed on substrates define functional elements of the devices, such as microprocessors, memory chips, etc. Similar lithographic techniques are also used in the formation of flat panel displays, micro-electro mechanical systems (MEMS), and other devices.SUMMARY

[0007] In some aspects, the techniques described herein relate to a modular conditioning apparatus including: a core having a first surface polished to optical contact quality; and a conditioning sheet having a grinding surface and a second surface opposite the grinding surface, the second surface polished to the optical contact quality for optically contacting the first surface such that that the conditioning sheet is removably bonded to the core.

[0008] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the grinding surface is elevated over a central surface of the conditioning sheet.

[0009] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the grinding surface is an annular surface.

[0010] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the second surface is not flat prior to optically contacting the first surface.

[0011] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the second surface is flat after optically contacting the first surface.

[0012] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the core includes SiSiC.

[0013] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the conditioning sheet includes SiSiC or SiC.

[0014] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the first surface and the second surface are the same material.

[0015] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the grinding surface includes a diamond film coating.

[0016] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the core and the conditioning sheet have coefficients of thermal expansion within 10% of each other.

[0017] In some aspects, the techniques described herein relate to a modular conditioning apparatus, wherein the optical contact quality includes a smoothness of less than 1 nm peak-to-valley.

[0018] In some aspects, the techniques described herein relate to a method including: polishing a first side of a core of a modular conditioning apparatus to an optical contact quality; polishing a second side of a conditioning sheet to the optical contact quality; forming a grinding surface on the conditioning sheet; and optically contacting the second side of the conditioning sheet to the first side of the core.

[0019] In some aspects, the techniques described herein relate to a method, further including removing a worn conditioning sheet from the core by separating at a prior optical contact between the worn conditioning sheet and the core.

[0020] In some aspects, the techniques described herein relate to a method, further including depositing a coating on the conditioning sheet to form the grinding surface.

[0021] In some aspects, the techniques described herein relate to a method, further including baking the conditioning sheet as part of depositing the coating.

[0022] In some aspects, the techniques described herein relate to a method, wherein a temperature used for the baking is at least 600 degrees Celsius.

[0023] In some aspects, the techniques described herein relate to a semiconductor device manufacturing method including: conditioning a support surface for a substrate with a modular conditioning apparatus, the conditioning causing the support surface to have a prescribed flatness; receiving the substrate on the support surface, the substrate having a photoresist layer; directing EUV or DUV radiation from a radiation source to transfer a pattern from a mask onto the photoresist layer; and removing a portion of the photoresist layer to form the pattern over the substrate.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations.

[0025] Figure 1 illustrates a block diagram of various subsystems of a lithographic projection apparatus, according to an embodiment.

[0026] Figure 2 illustrates an exemplary flow chart for simulating lithography in a lithographic projection apparatus, according to an embodiment.

[0027] Figure 3 is a simplified top view of a wafer resting upon a burl surface of a wafer table, according to an embodiment.

[0028] Figure 4 illustrates an example of a conditioning apparatus used to condition a wafer table, according to an embodiment.

[0029] Figure 5A illustrates a bottom view of a modular conditioning apparatus, according to an embodiment.

[0030] Figure 5B illustrates a side view of the modular conditioning apparatus as being formed by joining a conditioning sheet to a core, according to an embodiment.

[0031] Figure 5C shows the removably bonded core and conditioning sheet, according to an embodiment.

[0032] Figure 6A shows a modular conditioning apparatus with a conditioning sheet that is not flat prior to being bound to a core, according to an embodiment.

[0033] Figure 6B shows the conditioning sheet after being bound to the core, according to an embodiment.

[0034] Figure 7 depicts a method of manufacturing a modular conditioning apparatus, according to an embodiment.DETAILED DESCRIPTION

[0035] Although specific reference may be made in this text to the manufacture of ICs, it should be explicitly understood that the description herein has many other possible applications. For example, it may be employed in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid-crystal display panels, thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “reticle”, “wafer” or “die” in this text should be considered as interchangeable with the more general terms “mask”, “substrate” and “target portion”, respectively.

[0036] In the present document, the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation, including deep ultraviolet (DUV) radiation (e.g., with a wavelength of 365, 248, 193, 157 or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., with a wavelength in the range of about 5-100 nm).

[0037] The patterning device can comprise, or can form, one or more design layouts. The design layout can be generated utilizing computer-aided design (CAD) programs, this process often being referred to as electronic design automation (EDA). Most CAD programs follow a set of predetermined design rules in order to create functional design layouts / patterning devices. These rules are set by processing and design limitations. For example, design rules define the space tolerance between devices (such as gates, capacitors, etc.) or interconnect lines, so as to ensure that the devices or lines do not interact with one another in an undesirable way. One or more of the design rule limitations may be referred to as “critical dimension” (CD). A critical dimension of a device can be defined as the smallest width of aline or hole or the smallest space between two lines or two holes. Thus, the CD determines the overall size and density of the designed device. Of course, one of the goals in device fabrication is to faithfully reproduce the original design intent on the substrate (via the patterning device).

[0038] The term “mask” or “patterning device” as employed in this text may be broadly interpreted as referring to a generic patterning device that can be used to endow an incoming radiation beam with a patterned cross-section, corresponding to a pattern that is to be created in a target portion of the substrate; the term “light valve” can also be used in this context. Besides the classic mask (transmissive or reflective; binary, phase-shifting, hybrid, etc.), examples of other such patterning devices include a programmable mirror array and a programmable LCD array.

[0039] An example of a programmable mirror array can be a matrix-addressable surface having a viscoelastic control layer and a reflective surface. The basic principle behind such an apparatus is that (for example) addressed areas of the reflective surface reflect incident radiation as diffracted radiation, whereas unaddressed areas reflect incident radiation as undiffracted radiation. Using an appropriate filter, the said undiffracted radiation can be filtered out of the reflected beam, leaving only the diffracted radiation behind; in this manner, the beam becomes patterned according to the addressing pattern of the matrix-addressable surface. The required matrix addressing can be performed using suitable electronic methods.

[0040] An example of a programmable LCD array is given in U.S. Patent No. 5,229,872, the contents of which are incorporated herein by reference.

[0041] Figure 1 illustrates a block diagram of various subsystems of a lithographic projection apparatus 10A, according to an embodiment. Major components are a radiation source 12A, which may be a deep ultraviolet excimer laser source or other type of source including an extreme ultraviolet (EUV) source (as discussed above, the lithographic projection apparatus itself need not have the radiation source), illumination optics which, e.g., define the partial coherence (denoted as sigma) and which may include optics 14A, 16Aa, and 16Ab that shape radiation from the source 12A; a patterning device 18A; and transmission optics 16Ac that project an image of the patterning device pattern onto a substrate plane 22A. An adjustable filter or aperture 20A at the pupil plane of the projection optics may restrict the range of beam angles that impinge on the substrate plane 22A, where the largest possible angle defines the numerical aperture of the projection optics NA= n sin(0max), wherein n is the refractive index of the media between the substrate and the last element of the projection optics, and ©max is the largest angle of the beam exiting from the projection optics that can still impinge on the substrate plane 22A.

[0042] In a lithographic projection apparatus, a source provides illumination (i.e., radiation) to a patterning device and projection optics direct and shape the illumination, via the patterning device, onto a substrate. The projection optics may include at least some of the components 14A, 16Aa, 16Ab, and 16Ac. An aerial image (Al) is the radiation intensity distribution at substrate level. A resist model can be used to calculate the resist image from the aerial image, an example of which can be found in U.S. Patent Application Publication No. 2009-0157630, the contents of which are hereby incorporated hereinby reference. The resist model is related only to properties of the resist layer (e.g., effects of chemical processes which occur during exposure, post-exposure bake (PEB) and development). Optical properties of the lithographic projection apparatus (e.g., properties of the illumination, the patterning device and the projection optics) dictate the aerial image and can be defined in an optical model. Since the patterning device used in the lithographic projection apparatus can be changed, it is desirable to separate the optical properties of the patterning device from the optical properties of the rest of the lithographic projection apparatus including at least the source and the projection optics. Details of techniques and models used to transform a design layout into various lithographic images (e.g., an aerial image, a resist image, etc.), apply OPC using those techniques and models and evaluate performance (e.g., in terms of process window) are described in U.S. Patent Application Publication Nos. 2008-0301620, 2007-0050749, 2007-0031745, 2008-0309897, 2010-0162197, and 2010-0180251, the contents of each are hereby incorporated by reference.

[0043] One aspect of understanding a lithographic process is understanding the interaction of the radiation and the patterning device. The electromagnetic field of the radiation after the radiation passes the patterning device may be determined from the electromagnetic field of the radiation before the radiation reaches the patterning device and a function that characterizes the interaction. This function may be referred to as the mask transmission function (which can be used to describe the interaction by a transmissive patterning device and / or a reflective patterning device).

[0044] The mask transmission function may have a variety of different forms. One form is binary. A binary mask transmission function has either of two values (e.g., zero and a positive constant) at any given location on the patterning device. A mask transmission function in the binary form may be referred to as a binary mask. Another form is continuous. Namely, the modulus of the transmittance (or reflectance) of the patterning device is a continuous function of the location on the patterning device. The phase of the transmittance (or reflectance) may also be a continuous function of the location on the patterning device. A mask transmission function in the continuous form may be referred to as a continuous tone mask or a continuous transmission mask (CTM). For example, the CTM may be represented as a pixelated image, where each pixel may be assigned a value between 0 and 1 (e.g., 0.1, 0.2, 0.3, etc.) instead of binary value of either 0 or 1. In an embodiment, CTM may be a pixelated gray scale image, where each pixel having values (e.g., within a range [-255, 255], normalized values within a range [0, 1] or [-1, 1] or other appropriate ranges).

[0045] The thin-mask approximation, also called the Kirchhoff boundary condition, is widely used to simplify the determination of the interaction of the radiation and the patterning device. The thin-mask approximation assumes that the thickness of the structures on the patterning device is very small compared with the wavelength and that the widths of the structures on the mask are very large compared with the wavelength. Therefore, the thin-mask approximation assumes the electromagnetic field after the patterning device is the multiplication of the incident electromagnetic field with the mask transmission function. However, as lithographic processes use radiation of shorter and shorterwavelengths, and the structures on the patterning device become smaller and smaller, the assumption of the thin-mask approximation can break down. For example, interaction of the radiation with the structures (e.g., edges between the top surface and a sidewall) because of their finite thicknesses (“mask 3D effect” or “M3D”) may become significant. Encompassing this scattering in the mask transmission function may enable the mask transmission function to better capture the interaction of the radiation with the patterning device. A mask transmission function under the thin-mask approximation may be referred to as a thin-mask transmission function. A mask transmission function encompassing M3D may be referred to as a M3D mask transmission function.

[0046] According to an embodiment of the present disclosure, one or more images may be generated. The images includes various types of signal that may be characterized by pixel values or intensity values of each pixel. Depending on the relative values of the pixel within the image, the signal may be referred as, for example, a weak signal or a strong signal, as may be understood by a person of ordinary skill in the art. The term “strong” and “weak” are relative terms based on intensity values of pixels within an image and specific values of intensity may not limit scope of the present disclosure. In an embodiment, the strong and weak signal may be identified based on a selected threshold value. In an embodiment, the threshold value may be fixed (e.g., a midpoint of a highest intensity and a lowest intensity of pixel within the image). In an embodiment, a strong signal may refer to a signal with values greater than or equal to an average signal value across the image and a weak signal may refer to signal with values less than the average signal value. In an embodiment, the relative intensity value may be based on percentage. For example, the weak signal may be signal having intensity less than 50% of the highest intensity of the pixel (e.g., pixels corresponding to target pattern may be considered pixels with highest intensity) within the image. Furthermore, each pixel within an image may be considered as a variable. In an embodiment, derivatives or partial derivatives may be determined with respect to each pixel within the image and the values of each pixel may be determined or modified according to a cost function based evaluation and / or gradient based computation of the cost function. For example, a CTM image may include pixels, where each pixel is a variable that can take any real value.

[0047] Figure 2 illustrates an exemplary flow chart for simulating lithography in a lithographic projection apparatus, according to an embodiment. Source model 31 represents optical characteristics (including radiation intensity distribution and / or phase distribution) of the source. Projection optics model 32 represents optical characteristics (including changes to the radiation intensity distribution and / or the phase distribution caused by the projection optics) of the projection optics. Design layout model 35 represents optical characteristics of a design layout (including changes to the radiation intensity distribution and / or the phase distribution caused by a design layout), which is the representation of an arrangement of features on or formed by a patterning device. Aerial image 36 can be simulated from design layout model 35, projection optics model 32, and design layout model 35. Resist image 38 can be simulated from aerial image 36 using resist model 37. Simulation of lithography can, for example, predict contours and CDs in the resist image.

[0048] More specifically, it is noted that source model 31 can represent the optical characteristics of the source that include, but not limited to, numerical aperture settings, illumination sigma (o) settings as well as any particular illumination shape (e.g., off-axis radiation sources such as annular, quadrupole, dipole, etc.). Projection optics model 32 can represent the optical characteristics of the projection optics, including aberration, distortion, one or more refractive indexes, one or more physical sizes, one or more physical dimensions, etc. Design layout model 35 can represent one or more physical properties of a physical patterning device, as described, for example, in U.S. Patent No. 7,587,704, the contents of which are incorporated herein by reference. The objective of the simulation is to accurately predict, for example, edge placement, aerial image intensity slope and / or CD, which can then be compared against an intended design. The intended design is generally defined as a pre-OPC design layout which can be provided in a standardized digital file format such as GDSII or OASIS or other file format.

[0049] From this design layout, one or more portions may be identified, which are referred to as “clips.” In an embodiment, a set of clips is extracted, which represents the complicated patterns in the design layout (typically about 50 to 1000 clips, although any number of clips may be used). These patterns or clips represent small portions (i.e., circuits, cells or patterns) of the design and more specifically, the clips typically represent small portions for which particular attention and / or verification is needed. In other words, clips may be the portions of the design layout, or may be similar or have a similar behavior of portions of the design layout, where one or more critical features are identified either by experience (including clips provided by a customer), by trial and error, or by running a full-chip simulation. Clips may contain one or more test patterns or gauge patterns.

[0050] An initial larger set of clips may be provided a priori by a customer based on one or more known critical feature areas in a design layout which require particular image optimization. Alternatively, in another embodiment, an initial larger set of clips may be extracted from the entire design layout by using an automated (such as machine vision) or manual algorithm that identifies the one or more critical feature areas.

[0051] In a lithographic projection apparatus, as an example, a cost function may be expressed aswhere (z1;z2, ••• , zN) are N design variables or values thereof. fp(z-[,z2, -" ,zN) can be a function of the design variables (z1;z2, • • • , zw) such as a difference between an actual value and an intended value of a characteristic for a set of values of the design variables of (z1;z2, ••• , zN). wpis a weight constant associated with / p(z1,z2, --- ,zN). For example, the characteristic may be a position of an edge of a pattern, measured at a given point on the edge. Different fp(z1;z2, • • • , zw) may have different weight wp. For example, if a particular edge has a narrow range of permitted positions, the weight wpfor the fp(z^, z2, ••• ,zN) representing the difference between the actual position and the intended position ofthe edge may be given a higher value. fp(z1,z2, ---,zN') can also be a function of an interlayer characteristic, which is in turn a function of the design variables (z1;z2, '" >ZN) ■ Of course, CF(z1,z2, --- ,zw) is not limited to the form in Eq. 1. CF(z1,z2, --- ,zw) can be in any other suitable form.

[0052] The cost function may represent any one or more suitable characteristics of the lithographic projection apparatus, lithographic process or the substrate, for instance, focus, CD, image shift, image distortion, image rotation, stochastic variation, throughput, local CD variation, process window, an interlayer characteristic, or a combination thereof. In one embodiment, the design variables (z1,z2, --- ,zw) comprise one or more selected from dose, global bias of the patterning device, and / or shape of illumination. Since it is the resist image that often dictates the pattern on a substrate, the cost function may include a function that represents one or more characteristics of the resist image. For example, fp(z1;z2, • • • , zw) can be simply a distance between a point in the resist image to an intended position of that point (i.e., edge placement error FPFp(z1,z2, ••• , zN). The design variables can include any adjustable parameter such as an adjustable parameter of the source, the patterning device, the projection optics, dose, focus, etc.

[0053] The lithographic apparatus may include components collectively called a “wavefront manipulator” that can be used to adjust the shape of a wavefront and intensity distribution and / or phase shift of a radiation beam. In an embodiment, the lithographic apparatus can adjust a wavefront and intensity distribution at any location along an optical path of the lithographic projection apparatus, such as before the patterning device, near a pupil plane, near an image plane, and / or near a focal plane. The wavefront manipulator can be used to correct or compensate for certain distortions of the wavefront and intensity distribution and / or phase shift caused by, for example, the source, the patterning device, temperature variation in the lithographic projection apparatus, thermal expansion of components of the lithographic projection apparatus, etc. Adjusting the wavefront and intensity distribution and / or phase shift can change values of the characteristics represented by the cost function. Such changes can be simulated from a model or actually measured. The design variables can include parameters of the wavefront manipulator.

[0054] The design variables may have constraints, which can be expressed as (z1;z2, ■■■ ,zN') G Z, where Z is a set of possible values of the design variables. One possible constraint on the design variables may be imposed by a desired throughput of the lithographic projection apparatus. Without such a constraint imposed by the desired throughput, the optimization may yield a set of values of the design variables that are unrealistic. For example, if the dose is a design variable, without such a constraint, the optimization may yield a dose value that makes the throughput economically impossible. However, the usefulness of constraints should not be interpreted as a necessity. For example, the throughput may be affected by the pupil fill ratio. For some illumination designs, a low pupil fill ratio may discard radiation, leading to lower throughput. Throughput may also be affected by the resistchemistry. Slower resist (e.g., a resist that requires higher amount of radiation to be properly exposed) leads to lower throughput.

[0055] Figure 3 illustrates a simplified top view of a substrate 310 resting upon a burl surface 340 of a wafer table 320, according to an embodiment. When the above processes for manufacturing an integrated circuit or other devices by a lithographic process are used, the substrate receiving the printing (which can be a wafer) can be supported by what the present disclosure refers to herein as a “wafer table” (regardless of whether it is a wafer or other structure that is being supported).

[0056] An example wafer table 320 is shown with a number of burls 330 that combine to form burl surface 340. An example substrate 310 can optionally rest upon burl surfaces 340, also shown in a side view by the expanded inset. Burls 330 can provide some nominal separation (and reduction of contact surface area) between substrate 310 and wafer table 320. For example, by supporting substrate 310 on burl surface 340 (which can be made up of any number of burls 330 having some separation between them), sticking due to van der Waals forces can be reduced as well as the avoidance of vacuums, air pockets, etc.

[0057] The embodiments described herein generally refer to apparatuses for conditioning a surface of a wafer table that can be utilized for supporting a substrate, such as a wafer. In various embodiments, the wafer table may or may not contain burls or other surface features for conditioning with the disclosed conditioning apparatuses.

[0058] Figure 4 illustrates an example of a conditioning apparatus used to condition a wafer table, according to an embodiment. Conditioning apparatus 410, which can include the later-described modular conditioning apparatus of the present disclosure, can have a grinding surface 420 that can be utilized to condition the surface of wafer table 320. Conditioning, as used herein, can include smoothing, roughening, texturing, polishing, etc. This can include conditioning the burl surfaces 340 of burls 330, if present on wafer table 320. The double arrow shown in Figure 4 represents relative movement of conditioning apparatus 410 to wafer table 320. In various embodiments, wafer table 320 can be fixed and conditioning apparatus 410 can move, conditioning apparatus 410 can be fixed and wafer table 320 can move, or conditioning apparatus 410 and wafer table 320 can both move, but with some differential in motion to allow the conditioning. In some embodiments, wafer table 320 can be scanned (e.g., in linear directions, such as in a raster motion) underneath a rotating conditioning apparatus 410.

[0059] Figure 5A illustrates a bottom view of a modular conditioning apparatus, according to an embodiment. As shown by the bottom view of Figure 5 A (looking at the grinding surface), modular conditioning apparatus 510 can be circular in shape to form a generally cylindrical object, though other shapes are possible such as rectangular, an irregular shape, etc. Modular conditioning apparatus 510 can have a grinding surface, which can be the active surface that makes contact with the wafer table to be conditioned.

[0060] Figure 5B illustrates a side view of modular conditioning apparatus 510 as being formed by joining conditioning sheet 520 to core 530, according to an embodiment. Modular conditioning apparatus 510 can include two parts, core 530, and conditioning sheet 520 that can be used to condition an object such as a wafer table. In some embodiments, conditioning sheet 520 can be much thinner than core 530, for example, 0.5 mm thick as compared to a 1-2 cm thick core 530. Core 530 and conditioning sheet 520 are advantageously designed to be separable such that conditioning sheet 520 can be removed and replaced when desired. This replaceability of conditioning sheet 520 provides several technical advantages that will be apparent from the present disclosure. As shown in Figure 5B, modular conditioning apparatus 510 can include core 530 having first surface 532 designed for removably affixing to conditioning sheet. In some embodiments, first surface 532 can be polished to optical contact quality (described further herein). Figure 5B also illustrates that modular conditioning apparatus 510 can include conditioning sheet 520 having grinding surface 540, which in some embodiments may only be a portion of the available surface area of conditioning sheet 520, such as an outer periphery. In some embodiments, grinding surface 540 can be provided by chemical vapor deposition (CVD) of a diamond film coating. Conditioning sheet 520 can include second surface 522 opposite grinding surface 540 designed for removably affixing to core 530, as shown by the arrow between conditioning sheet 520 and core 530. In some embodiments, second surface 522 can be polished to optical contact quality for optically contacting first surface 532 such that that conditioning sheet 520 is removably bonded to core 530.

[0061] In some embodiments, the surface(s) being of optical contact quality can include them having a smoothness of less than 1 nm peak-to-valley (PV), less than 0.5 nm PV, etc. In some embodiments, due to the optical contact strength being proportional to the smoothness but conditioning sheet 520 still intended as being removable, the smoothness may include 0.1 nm PV.

[0062] Figure 5C shows the removably bonded core 530 and conditioning sheet 520, according to an embodiment. The optical contact forms a strong but removable bond that can be broken by, for example, pushing a thin tool between core 530 and conditioning sheet 520, using an adhesive on the exposed surface(s) to allow pulling them apart, using grasping tools to pull them apart, etc.

[0063] Grinding surface 540 is depicted in Figures 5B and 5C as optionally elevated over a central surface 524 of conditioning sheet 520. As shown in the depicted example, grinding surface 540 can be an annular surface, but in general can correspond to the outer periphery of conditioning sheet 520 and / or elevated portion 526. Conditioning sheet 520 can also be of the same shape as core 530 such that conditioning sheet 520 can reach the outer dimension of core 530. As one example of how modular conditioning apparatus 510 may be constructed, conditioning sheet 520 can be made oversized relative to core 530. This oversized conditioning sheet can then be optically contacted to core 530. A laser or other cutter can be utilized to remove the outer oversized portion, leaving conditioning sheet 520 with the same or similar radius as core 530. The same laser, or other ablative tool, can then be utilized to remove material from the internal region of conditioning sheet 520 to form elevated portion 526.

[0064] Figure 6 A shows modular conditioning apparatus 610 with conditioning sheet 620 that is not flat prior to being bound to core 630, according to an embodiment. The process of adding a coating to grinding surface 640 may often be done at high temperatures, which may deform or warp conditioning sheet 620. For example, the CVD of a diamond film coating may be deposited at approximately 850°C. The warping that these temperatures can cause is depicted in Figure 6A (greatly exaggerated for illustrative purposes). As such, in some embodiments, second surface 622 may not be flat prior to optically contacting first surface 632.

[0065] Figure 6B shows conditioning sheet 620 after being bound to core 630, according to an embodiment. Due to the strength of the optical contact bond, second surface 622 can be flat after optically contacting first surface 632. This imparting of the first surface flatness (which is retained because core 630 is not subject to high temperature conditions) can propagate through to the grinding surface 640, thus also improving its flatness and making it more suitable for conditioning.

[0066] In various embodiments, core can include SiSiC and conditioning sheet can include SiSiC or SiC. In some embodiments, first surface and second surface can be the same material (e.g., either of the above materials or another material altogether). Other materials that can be used for the core and / or conditioning sheet can include SiC, SiSiC, boron carbide, boron nitride, aluminum oxide, fused silica, etc. To improve the retention of the bond during use, which due to friction or other conditions can involve large temperature changes, core and conditioning sheet can have similar coefficients of thermal expansion (e.g., within 10%, 5%, etc., of each other).

[0067] Figure 7 depicts a method of manufacturing a modular conditioning apparatus, according to an embodiment. Method 700 can include, at 710, polishing a first side of a core of a modular conditioning apparatus to an optical contact quality. At 720, a second side of a conditioning sheet can be polished to the optical contact quality. In some embodiments, a coating can be added to the contacting surfaces via methods such as physical vapor deposition, chemical vapor deposition, atomic layer deposition, etc. Such a coating can increase the strength and ease of optical contact creation. At 730, a grinding surface can be formed on the conditioning sheet. This can include, for example, depositing a coating on the conditioning sheet to form the grinding surface. Some methods can also include baking the conditioning sheet as part of depositing the coating, and in some cases the temperature used for the baking can be at least 600 degrees Celsius. However, in some alternatives, lower-temperature baking methods can be utilized. At 740, second side of the conditioning sheet can be optically contacted to the first side of the core. In various embodiments, the order in which the above steps are done can be changed and so the order is not an essential feature. For example, the grinding surface can be formed on the conditioning sheet either before or after polishing second side of the conditioning sheet.

[0068] Once manufactured, some methods can include the previously-described replacement of the removable conditioning sheet. This can include, for example, removing a worn conditioning sheet from the core by separating at a prior optical contact between the worn conditioning sheet and the core.

[0069] Example embodiments of the present technology are set out in the following numbered clauses:1. A modular conditioning apparatus comprising:a core having a first surface polished to optical contact quality; anda conditioning sheet having a grinding surface and a second surface opposite the grinding surface, the second surface polished to the optical contact quality for optically contacting the first surface such that that the conditioning sheet is removably bonded to the core.2. The modular conditioning apparatus of clause 1, wherein the grinding surface is elevated over a central surface of the conditioning sheet.3. The modular conditioning apparatus of clause 2, wherein the grinding surface is an annular surface.4. The modular conditioning apparatus of clause 1 , wherein the second surface is not flat prior to optically contacting the first surface.5. The modular conditioning apparatus of clause 3, wherein the second surface is flat after optically contacting the first surface.6. The modular conditioning apparatus of clause 1 , wherein the core comprises SiSiC.7. The modular conditioning apparatus of clause 1, wherein the conditioning sheet comprises SiSiC or SiC.8. The modular conditioning apparatus of clause 1 , wherein the first surface and the second surface are the same material.9. The modular conditioning apparatus of clause 1, wherein the grinding surface comprises a diamond film coating.10. The modular conditioning apparatus of clause 1, wherein the core and the conditioning sheet have coefficients of thermal expansion within 10% of each other.11. The modular conditioning apparatus of clause 1 , wherein the optical contact quality comprises a smoothness of less than 1 nm peak-to-valley.12. A method comprising:polishing a first side of a core of a modular conditioning apparatus to an optical contact quality; polishing a second side of a conditioning sheet to the optical contact quality;forming a grinding surface on the conditioning sheet; andoptically contacting the second side of the conditioning sheet to the first side of the core. 13. The method of clause 10, further comprising removing a worn conditioning sheet from the core by separating at a prior optical contact between the worn conditioning sheet and the core.14. The method of clause 10, further comprising depositing a coating on the conditioning sheet to form the grinding surface.15. The method of clause 12, further comprising baking the conditioning sheet as part of depositing the coating.16. The method of clause 13, wherein a temperature used for the baking is at least 600 degrees Celsius.17. A semiconductor device manufacturing method comprising:conditioning a support surface for a substrate with a modular conditioning apparatus, the conditioning causing the support surface to have a prescribed flatness;receiving the substrate on the support surface, the substrate having a photoresist layer; directing EUV or DUV radiation from a radiation source to transfer a pattern from a mask onto the photoresist layer; andremoving a portion of the photoresist layer to form the pattern over the substrate.

[0070] The lithographic apparatus and radiation source along with embodiments of the modular conditioning apparatus described herein can be used in a method for manufacturing a semiconductor device. A semiconductor device manufacturing method comprises conditioning a support surface for a substrate with a modular conditioning apparatus, the conditioning causing the support surface to have a prescribed flatness. The method can also include receiving the substrate, which can have a photoresist layer. The method further comprises directing an EUV or DUV radiation from a radiation source to transfer a pattern from a mask onto the photoresist layer. This can be achieved by a patterning device which is configured to form a patterned radiation beam, imparting the patterned radiation beam onto the photoresist layer. The method for manufacturing a semiconductor device further comprises the step of removing a portion of the photoresist layer to form the pattern over the substrate.

[0071] The substrate may be made of silicon or other semiconductor materials. Alternatively or additionally, the substrate may include other semiconductor materials such as germanium (Ge) or carbon (C). In some embodiments, the semiconductor substrate is made of a compound semiconductor such as III-V compound semiconductors, II- V compound semiconductors, and / or any suitable integration of Group IV materials. In some embodiments, the substrate may be a silicon-on-insulator (SOI) or a germanium-on-insulator (GOI) substrate.

[0072] The semiconductor device made from the substrate may have various device elements. Examples of semiconductor device elements that are formed over the substrate include transistors (e.g., planar or non-planar metal oxide semiconductor field effect transistors (MOSFET), bipolar junction transistors (BJT), high-voltage transistors, high-frequency transistors, etc.), diodes, CMOS image sensors, passive devices, and / or other applicable elements. Various processes may be performed to form the semiconductor device elements, such as deposition, etching, implantation, epitaxial growth, polishing, thermal treatment, and / or other suitable processes. In some embodiments, the substrate is coated with a photoresist layer sensitive to the EUV light.

[0073] The combinations and sub-combinations of the elements disclosed herein constitute separate embodiments and are provided as examples only. Also, the descriptions above are intended to be illustrative, 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 out below.

Claims

CLAIMS1. A modular conditioning apparatus comprising:a core having a first surface polished to optical contact quality; anda conditioning sheet having a grinding surface and a second surface opposite the grinding surface, the second surface polished to the optical contact quality for optically contacting the first surface such that that the conditioning sheet is removably bonded to the core.

2. The modular conditioning apparatus of claim 1, wherein:the grinding surface is elevated over a central surface of the conditioning sheet; and the grinding surface is an annular surface.

3. The modular conditioning apparatus of claim 1, wherein:the second surface is not flat prior to optically contacting the first surface; andthe second surface is flat after optically contacting the first surface.

4. The modular conditioning apparatus of claim 1 , wherein the core comprises SiSiC.

5. The modular conditioning apparatus of claim 1, wherein the conditioning sheet comprises SiSiC or SiC.

6. The modular conditioning apparatus of claim 1 , wherein the first surface and the second surface are the same material.

7. The modular conditioning apparatus of claim 1, wherein the grinding surface comprises a diamond film coating.

8. The modular conditioning apparatus of claim 1, wherein the core and the conditioning sheet have coefficients of thermal expansion within 10% of each other.

9. The modular conditioning apparatus of claim 1, wherein the optical contact quality comprises a smoothness of less than 1 nm peak-to-valley.

10. A method comprising:polishing a first side of a core of a modular conditioning apparatus to an optical contact quality;polishing a second side of a conditioning sheet to the optical contact quality;forming a grinding surface on the conditioning sheet; andoptically contacting the second side of the conditioning sheet to the first side of the core.

11. The method of claim 10, further comprising removing a worn conditioning sheet from the core by separating at a prior optical contact between the worn conditioning sheet and the core.

12. The method of claim 10, further comprising depositing a coating on the conditioning sheet to form the grinding surface.

13. The method of claim 12, further comprising baking the conditioning sheet as part of depositing the coating.

14. The method of claim 13, wherein a temperature used for the baking is at least 600 degrees Celsius.

15. A semiconductor device manufacturing method comprising:conditioning a support surface for a substrate with a modular conditioning apparatus, the conditioning causing the support surface to have a prescribed flatness;receiving the substrate on the support surface, the substrate having a photoresist layer; directing EUV or DUV radiation from a radiation source to transfer a pattern from a mask onto the photoresist layer; andremoving a portion of the photoresist layer to form the pattern over the substrate.

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