CN116762161A

CN116762161A - Vacuum tab bond fixture for substrate table and compliant burl application

Info

Publication number: CN116762161A
Application number: CN202180088313.5A
Authority: CN
Inventors: A·阿里汉; T·尤特迪杰克; J·B·C·恩格伦; D·卡米涅茨基; B·L·W·M·范德文; T·波伊兹; L·M·勒瓦希尔; J·V·奥弗坎普; J·A·C·M·皮南伯格; K·范伯克尔; G·J·迪圭多; A·C·小索希; I·西格尔; B·A·G·罗曼斯; M·B·I·哈贝茨
Original assignee: ASML Holding NV
Current assignee: ASML Holding NV
Priority date: 2020-12-29
Filing date: 2021-12-02
Publication date: 2023-09-15

Abstract

Systems, apparatuses, and methods for manufacturing a substrate table are provided. An example method may include: a vacuum plate is formed that includes a plurality of vacuum connections and a plurality of recesses configured to receive a plurality of burls disposed on a core for supporting an object such as a wafer. Alternatively, at least one nub may be surrounded in part or in whole by a groove. The example method may further include: the core is mounted to an electrostatic sheet using a vacuum sheet, the electrostatic sheet comprising a plurality of apertures configured to receive a plurality of nubs. Optionally, the example method may include: the core is mounted to the electrostatic sheet using a vacuum sheet such that the plurality of recesses of the vacuum sheet are aligned with the plurality of burls of the core and the plurality of apertures of the electrostatic sheet.

Description

Vacuum tab bond fixture for substrate table and compliant burl application

Cross Reference to Related Applications

The present application claims priority from (1) U.S. provisional patent application No. 63/131,527, which was filed on even 29 th 12, 2020, and (2) U.S. provisional patent application No. 63/272,504, which was filed on even 27, 10, 2021, both of which are incorporated herein by reference in their entireties.

Technical Field

The present disclosure relates to a substrate table and a method for forming burls and nanostructures on a surface of a substrate table.

Background

A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. Lithographic apparatus can be used, for example, in the manufacture of Integrated Circuits (ICs). In this example, a patterning device (which is referred to interchangeably as a mask or a reticle) may be used to generate a circuit pattern to be formed on each layer of the IC being formed, and this pattern may be transferred to a target portion (e.g. comprising part of one or several dies) on a substrate (e.g. a silicon wafer). The transfer pattern is typically imaged onto a layer of radiation-sensitive material (e.g., resist) disposed on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time; and so-called scanners in which each target portion is irradiated by scanning the pattern by a radiation beam in a given direction (the "scanning" direction) while synchronously scanning the target portion in a direction parallel to the scanning direction or in a direction parallel to and opposite to the scanning direction. The pattern may also be transferred from the patterning device to the substrate by imprinting the pattern onto the substrate.

With the continued progress of semiconductor manufacturing processes, the size of circuit elements has been reduced continuously for decades, and the number of functional elements such as transistors per device has been steadily increasing, following a trend commonly referred to as moore's law. To keep pace with moore's law, the semiconductor industry is pursuing technologies that enable smaller and smaller features to be produced. To project a pattern onto a substrate, a lithographic apparatus may use electromagnetic radiation. The wavelength of the radiation determines the minimum size of features that can be patterned on the substrate. Typical wavelengths currently used in Deep Ultraviolet (DUV) radiation systems are 365nm (i-line), 248nm and 193nm; and a typical wavelength used in an Extreme Ultraviolet (EUV) radiation system is 13.5nm. EUV radiation, e.g., electromagnetic radiation having a wavelength of about 50 nanometers (nm) or less and including light having a wavelength of about 13.5nm (also sometimes referred to as soft x-rays), may be used in or with lithographic apparatus to produce very small features in or on a substrate (e.g., a silicon wafer). Lithographic apparatus using EUV radiation having a wavelength in the range of 4nm to 20nm (e.g., 6.7nm or 13.5 nm) may be used to form smaller features on a substrate than lithographic apparatus using radiation, for example, 193 nm.

It may be desirable to specify and maintain frictional properties (e.g., friction, hardness, wear) on the surface of the substrate table. In some examples, the wafer chuck may be disposed on a surface of the substrate table. The wafer chuck may be, for example, a vacuum chuck for a DUV radiation system or an electrostatic chuck for an EUV radiation system. Due to the accuracy requirements of the lithographic process and the metrology process, the substrate table or the wafer holder attached thereto has surface level tolerances that are difficult to meet. Wafers (e.g., semiconductor substrates) that are relatively thin (e.g., <1.0 millimeters (mm) thick) compared to the width of their surface area (e.g., >100.0mm wide) are particularly sensitive to substrate table non-uniformities. Additionally, the ultra-smooth surfaces of the contacts may adhere together, which can be problematic when the substrate must be detached from the substrate table. To reduce the smoothness of the surface interfacing with the wafer, the surface of the substrate table or wafer holder may comprise protrusions formed by patterning and etching the substrate. However, the prior art fails to control the bonding location to sub-micron (micrometer) tolerances over and over a substrate area of 300mm diameter.

Disclosure of Invention

The present disclosure describes various aspects of systems, apparatus, and methods for manufacturing and using a substrate table with burls configured to support a substrate in a DUV or EUV radiation system. For example, the substrate table may comprise a core and an electrostatic plate for an EUV radiation system.

In some aspects, the present disclosure provides for using a vacuum sheet bonding fixture to mount a core to an electrostatic sheet. In some aspects, the vacuum plate may include a mounting structure, such as a "ring" around each aperture of the electrostatic plate. For example, the vacuum sheet may be configured such that it may hold an electrostatic sheet having apertures, and the vacuum sheet may contain apertures aligned with the apertures of the electrostatic sheet. The vacuum sheet may also be configured to receive a core having nubs thereon that fit into the holes such that the depth of the holes defines the distance between the top of the electrostatic sheet and the top of the nubs.

In some aspects, the present disclosure also provides for providing "flexible burls" applications on substrate tables (e.g., DUV wafer tables including cores with flexible burls, EUV wafer tables including electrostatic sheets mounted to cores with burls) using lateral stiffness and vacuum accumulation tuning. In some aspects, the term "flexible burls" as used herein refers to burls that are partially or fully surrounded by grooves.

In some aspects, the present disclosure describes a substrate table. The substrate table may comprise a core comprising a plurality of burls for supporting an object such as a wafer (e.g. burls may be provided on a top side of the core facing the wafer). The core may also include a plurality of grooves. Each of the plurality of burls may be surrounded by a respective groove of the plurality of grooves. In some aspects, at least a portion of the core may be formed of siliconized silicon carbide (SiSiC) or silicon carbide (SiC). In some aspects, at least a portion of the plurality of burls may be formed of SiSiC, siC, diamond-like carbon (DLC), aluminum nitride (AlN), silicon nitride (SiN), or chromium nitride (CrN).

In some aspects, in a plurality of burlsMay have a stiffness of less than about 10 meganewtons per meter (10 in scientific notation) ⁷ Nm ^-1 The method comprises the steps of carrying out a first treatment on the surface of the Or 1e 7N/m). In some aspects, the plurality of burls can include at least one burl having a first taper angle toward a top of the burl and a second taper angle toward a bottom of the burl. In some aspects, the plurality of burls may include (i) a first burl surrounded by the first groove and disposed in a first region (e.g., a central region) of the core; and (ii) a second burl surrounded by a second groove and disposed in a second region (e.g., a peripheral region) of the core. In these aspects, the depth of the first groove may be less than the depth of the second groove, the length of the second burls may be greater than the length of the first burls, the stiffness of the second burls may be less than the stiffness of the first burls, or a combination thereof.

In some aspects, the core may also be configured to be connected (e.g., using a vacuum plate) to an electrostatic plate that includes a plurality of apertures configured to receive the plurality of burls of the core such that the plurality of burls of the core are aligned with the plurality of apertures of the electrostatic plate.

In some aspects, this disclosure describes an apparatus. The apparatus may include a vacuum plate including a plurality of vacuum connections and a plurality of recesses configured to receive the plurality of burls of the core. In some aspects, at least a portion of the vacuum sheet may be formed from fused silica. In some aspects, the stiffness of the vacuum panel may be less than the stiffness of the core.

In some aspects, the vacuum plate may be configured to mount the core to an electrostatic plate comprising a plurality of apertures configured to receive a plurality of nubs of the core. In some aspects, the plurality of recesses of the vacuum plate may be configured to align with a plurality of apertures of the electrostatic plate. In some aspects, the stiffness of the vacuum sheet may be less than the stiffness of the core, and optionally greater than the stiffness of the electrostatic sheet.

In some aspects, the vacuum sheet may be configured to: the electrostatic sheet is vacuum clamped to the vacuum sheet in response to applying vacuum to the plurality of vacuum connections of the vacuum sheet. In some aspects, the vacuum sheet may include an electrode layer having one or more electrodes. In some aspects, the vacuum sheet may be configured to: the electrostatic sheet is electrostatically clamped to the vacuum sheet in response to applying one or more voltages to one or more of the one or more electrodes in the electrode layer of the vacuum sheet. In some aspects, at least a portion of the electrode layer of the vacuum sheet may be formed of copper (Cu) or chromium.

In some aspects, the vacuum sheet may include a coating on at least a portion of a side of the vacuum sheet facing the electrostatic sheet (e.g., at least in an area where the vacuum sheet touches the electrostatic sheet when the electrostatic sheet is clamped to the vacuum sheet). In some aspects, the properties of the coating may be configured such that strong or substantially permanent adhesion, e.g., optical contact, between the vacuum sheet and the electrostatic sheet is substantially prevented. In some aspects, at least a portion of the coating may be formed of CrN or DLC.

In some aspects, a method of manufacturing a device is described. The method may include: a vacuum panel is formed that includes a plurality of vacuum connections and a plurality of recesses configured to receive the plurality of burls of the core. In some aspects, the method may further comprise: the electrostatic sheet is mounted to the core using a vacuum sheet such that a plurality of recesses of the vacuum sheet are aligned with a plurality of apertures of the electrostatic sheet and a plurality of burls of the core.

In some aspects, the method may further comprise: a core is formed that includes a plurality of burls for supporting an object such as a wafer (e.g., burls may be provided on a top side of the core facing the wafer). In some aspects, the method may include: a groove is formed around at least one of the plurality of burls. In some aspects, the method may further comprise: an electrostatic sheet is formed that includes a plurality of apertures configured to receive a plurality of nubs.

Other features and the structure and operation of various aspects are described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the particular aspects described herein. Such aspects are presented herein for illustrative purposes only. Other aspects will be apparent to those skilled in the relevant art based on the teachings contained herein.

Drawings

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the various aspects of the invention and to enable one or more persons skilled in the relevant art to make and use the various aspects of the disclosure.

FIG. 1A is a schematic illustration of an example reflective lithographic apparatus according to some aspects of the present disclosure;

FIG. 1B is a schematic illustration of an example transmissive lithographic apparatus according to some aspects of the present disclosure;

FIG. 2 is a more detailed schematic illustration of the reflective lithographic apparatus shown in FIG. 1A, according to some aspects of the present disclosure;

FIG. 3 is a schematic illustration of a lithographic cell according to some aspects of the present disclosure;

FIG. 4 is a schematic illustration of an example substrate table according to some aspects of the disclosure.

FIG. 5 is a schematic illustration of a portion of an example EUV substrate table according to some aspects of the present disclosure.

6A, 6B and 6C are cross-sectional illustrations of a portion of an example EUV substrate table according to some aspects of the present disclosure.

FIG. 7 is a cross-sectional illustration of an area of an example EUV substrate table manufacturing system, according to some aspects of the present disclosure.

FIG. 8 is a cross-sectional illustration of an area of another example EUV substrate table manufacturing system, according to some aspects of the present disclosure.

Fig. 9A, 9B, 9C, 9D, 9E, 9F, and 9G are cross-sectional illustrations of example burls surrounded by example grooves in accordance with some aspects of the invention.

Fig. 10A and 10B are example graphs illustrating example in-plane deformation increments of example substrates as a function of radius of example arcuate and umbrella-shaped substrates, respectively, in accordance with some aspects of the present disclosure.

11A and 11B are plan and cross-sectional illustrations of an example substrate table surface including example burls surrounded by example grooves, according to some aspects of the disclosure.

Fig. 12 is an example method of manufacturing a device or portion thereof according to some aspects of the present disclosure.

Fig. 13A and 13B are cross-sectional illustrations of regions of an example EUV substrate table fabrication system according to some aspects of the present disclosure.

FIG. 14 is a cross-sectional illustration of an area of another example EUV substrate table manufacturing system, according to some aspects of the present disclosure.

Fig. 15A, 15B, and 15C are cross-sectional illustrations of example compliant layer surfaces including example nubs surrounded by example grooves, in accordance with some aspects of the present disclosure.

Fig. 16A and 16B are plan and cross-sectional illustrations of example compliant layer surfaces including example burls surrounded by example grooves, in accordance with some aspects of the present disclosure.

Fig. 17 is an example method of manufacturing an apparatus, or portion thereof, according to some aspects of the present disclosure.

Features and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements, unless otherwise indicated. Additionally, in general, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears. The drawings provided throughout this disclosure should not be construed as being drawn to scale unless otherwise indicated.

Detailed Description

The present specification discloses one or more embodiments that incorporate the features of the present disclosure. One or more of the disclosed embodiments merely describe the present disclosure. The scope of the present disclosure is not limited to one or more of the disclosed embodiments. The breadth and scope of the present disclosure are defined by the appended claims and their equivalents.

References in the specification to "one embodiment," "an example embodiment," etc., indicate that the embodiment or embodiments described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

Spatially relative terms may be used herein such as "under … …," "under … …," "under … …," "over … …," "over … …," "over … …," and the like, for convenience in describing the relationship of one element or feature to one or more other elements or features as illustrated. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The term "about" as used herein indicates a given amount of value that may vary based on a particular technology. The term "about" may refer to a given amount of a value that varies, for example, within 10% to 30% of the value (e.g., ±10%, ±20% or ±30% of the value) based on a particular technology.

SUMMARY

In one example, a substrate to be exposed by a lithographic apparatus may be supported by a substrate holder (e.g., a structure that directly supports the substrate), which in turn may be supported by a substrate table (e.g., a structure configured to support the substrate holder and provide an upper surface surrounding the substrate holder, such as a mirror block, stage, or table). In one example, the substrate holder may be a flat rigid disk corresponding in size and shape to the substrate, although it may have a different size or shape. In some aspects, the substrate holder can have an array of protrusions protruding from at least one surface (e.g., top surface, bottom surface, or both), referred to as nubs or nubs. There may be an array of protrusions on two opposite sides of the substrate holder. In this case, when the substrate holder is placed on the substrate table, the body of the substrate holder may be held a small distance above the substrate table, while the ends of the burls on one side of the substrate holder are located on the surface of the substrate table. Similarly, the substrate may be spaced from the body of the substrate holder when the substrate rests on top of the burls on opposite sides of the substrate holder. An example purpose of such an arrangement may be to help prevent particles (e.g. contaminating particles such as dust particles) that may be present on the substrate table or substrate holder from deforming the substrate holder or substrate. Since the total surface area of the burls may be only a small fraction of the total surface of the substrate or substrate holder, particles may be located between burls and thus the presence of particles may be substantially unaffected. In some aspects, the substrate holder and the substrate may be accommodated within a recess in the substrate table such that an upper surface of the substrate may be substantially coplanar with an upper surface of the substrate table.

Due to the high acceleration experienced by the substrate in high throughput lithographic apparatus, it may not be sufficient to allow the substrate to simply rest on the burls of the substrate holder; instead, the substrate may be clamped in place. Two methods of clamping the substrate in place include, but are not limited to, vacuum clamping and electrostatic clamping. In vacuum clamping, the space between the substrate holder and the substrate, and optionally the substrate table and the substrate holder, is partially evacuated so that the substrate is held in place by the higher pressure of the gas or liquid above the substrate. However, vacuum clamping may not be used in cases where the beam path and/or environment near the substrate or substrate holder is maintained at low or very low pressure, such as in EUV radiation lithography. In this case, it is impossible to generate a sufficiently large pressure difference across the substrate (or substrate holder) to clamp the substrate (substrate holder). Electrostatic clamping may be used. In electrostatic clamping, a potential difference is established between the substrate or an electrode plated on a lower surface thereof and an electrode provided on or in the substrate table and/or the substrate holder. The two electrodes behave as large capacitors and can generate a considerable clamping force at a reasonable potential difference. The electrostatic configuration may be such that a single electrode pair (one electrode on the substrate table and one electrode on the substrate) clamps the substrate table, the substrate holder and the substrate together. In one arrangement, one or more electrodes may be provided on or in the substrate holder such that the substrate holder is clamped to the substrate table and the substrate is clamped to the substrate holder alone.

However, there is a need for DUV and EUV substrate holders, which may include one or more vacuum clamps or electrostatic clamps, respectively, for clamping a substrate holder (e.g., a patterning device (e.g., a mask) holder or a wafer holder) to a substrate table (e.g., a patterning device table or a wafer table), clamping a substrate (e.g., a mask or a wafer) to a substrate holder, or both.

Vacuum sheet bonding fixing device

In one example, the example bonding fixture for the example substrate table may control the epoxy bonding position to sub-micron tolerances over an area greater than or equal to 300mm only when the component is substantially nano-flat. As a result, the non-nano-flatness of the components and their stiffness may be an obstacle that in some examples cannot be overcome and ultimately determine the lower limit of tolerance for the position of the two bonded portions. Further, geometrically complex components can be very difficult to make flat, and in some cases nano-flatness may not be possible. In other words, there is a need for a technique and design for bonding components together that is more tightly toleranced than its shape flatness.

In contrast, some aspects of the present disclosure may provide a vacuum sheet fixture configured to utilize vacuum to conform to the non-flatness of another stiffer component (e.g., a core). Other aspects of the present disclosure may provide a vacuum sheet clamp configured to utilize vacuum to maintain a more flexible component (e.g., an electrostatic sheet) in a quasi-flexible state, thereby enabling the component to conform to the non-flatness of a harder component. In some aspects, the desired gap may be prefabricated into the disclosed vacuum sheet fixture. In some aspects, the vacuum sheet fixture may have a specific offset preformed into it to align the components during bonding. The tolerances that can be achieved in the bonding may depend on vacuum sheet fixture manufacturing tolerances. Thus, in some aspects, achieving tighter and tighter tolerances becomes a matter of time and effort. The vacuum sheet fixture may use a flexibility that is not as stiff as the stiffer component and optionally stiffer than the more flexible component. Additionally or alternatively, desired tolerances may be achieved using a deformable tool in which a load is applied. For example, a compliant or deformable layer (e.g., polydimethylsiloxane (PDMS) or a soft low durometer polymer such as 20A durometer silicone) may be added to the vacuum sheet fixture and used to fine tune the gap by varying the clamping weight.

In some aspects, the present disclosure provides for manufacturing a substrate table comprising a vacuum sheet fixture. In some aspects, the present disclosure provides forming a core (e.g., a SiSiC or SiC core) that includes a plurality of burls for supporting an object. For example, the burls may be provided on the top side of the core facing the object, which may be a wafer or any other suitable object. In some aspects, such as where at least one burl is a flexible burl, the present invention provides for forming a groove around at least one burl of the plurality of burls. In some aspects, the present disclosure provides for forming a vacuum panel comprising a plurality of vacuum connections and a plurality of recesses configured to receive a plurality of nubs. In some aspects, the invention provides for mounting the vacuum plate to the core such that the plurality of recesses of the vacuum plate are aligned with the plurality of burls of the core. In some aspects, such as where the substrate table is to be used in an EUV radiation system, the present invention provides forming an electrostatic sheet comprising a plurality of apertures (e.g., holes) configured to receive a plurality of burls. In some aspects, the present disclosure provides for mounting a vacuum plate to an electrostatic plate and a core such that a plurality of recesses of the vacuum plate are aligned with a plurality of apertures of the electrostatic plate and a plurality of burls of the core.

The systems, apparatuses, methods, and computer program products disclosed herein have many exemplary aspects. For example, aspects of the present disclosure provide techniques to achieve sub-micron bonding tolerances. Due to the techniques described in this disclosure, the bonding position can be controlled to quarter micron tolerances over 300mm areas and larger.

Flexible burls for DUV radiation systems

In one example, the substrate may be held by a substrate table during exposure in a DUV radiation system. The substrate may rest on burls protruding from the surface of the substrate table. In one example, the burls can include about 30000 burls, wherein each burl has a height of between about 100 microns and about 200 microns, and each burl has a top diameter of between about 100 microns and about 500 microns. A vacuum may be created in the volume between the burls such that the substrate is urged toward the substrate table by a pressure differential above and below the substrate.

Loading the substrate onto the substrate table may be a dynamic process in which the interaction between the substrate and burls is complex, as well as time dependent gas pressure between the substrate and the substrate table due to locally varying distances (e.g., volume changes) between the substrate and the substrate table. During the loading process, the wafer may deform in-plane (e.g., in the horizontal direction), which may create a "wafer loading grid" (WLG) after loading. As used herein, WLG refers to residual in-plane deformation or stress, which depends on the initial shape of the substrate (e.g., 200 micron umbrella warpage, 200 micron bow warpage) and interactions with burls (e.g., friction and stiffness) during and after loading. WLG may produce overlay errors because at least a portion of WLG may not be reproducible and therefore may not be fully corrected; the spatial frequency may be too high to be measured by a limited number of marks per substrate and the scanner may not have sufficient correction capability.

In one example, DUV systems may have WLG problems in cases where the magnitude and spatial frequency of WLG fingerprints are difficult to correct or when subjected to WLG drift. In some cases, WLG may depend on total burl stiffness. The total burl stiffness can be a range of stiffness: substrate shear force plus substrate/burl contact stiffness plus burl geometry. For some substrate table burls geometries, the contact stiffness may be less than other stiffnesses, so that the total burl stiffness may be dominated. Further, the overall burl stiffness may be sensitive to variations in contact stiffness (e.g., due to different wafer backside, burl contamination, different burl roughness wear).

For example, in a DUV radiation system, aspects of the present disclosure may provide tuning of SiSiC planar height (or SiC planar height) between flexible burls to obtain good vacuum pressure build-up over time.

As used herein, the term "flexible burls" refers to burls surrounded by a partial or complete groove. In some aspects, the flexible burls may include hard burls (e.g., DLC burls with or without conductive burls tops) surrounded partially or entirely by grooves. In some aspects, the depth of the groove surrounding the flexible burls can be modified (e.g., increased, decreased, widened, narrowed) to achieve a desired lateral burl stiffness and vacuum volume. In some aspects, the flexible burls disclosed herein can include any combination of the features, structures, and techniques described below: european patent application No. 20163373 entitled "Object Holder, tool and Method of Manufacturing an Object Holder" filed on month 3 and 16 of 2020 and european patent application No. 20179524 entitled "Object Holder, electrostatic Sheet and Method for Making an Electrostatic Sheet", filed on month 6 and 11 of 2020, the entire contents of both of which are incorporated herein by reference.

In some aspects, the invention provides a technique for fabricating flexible burls on one or more substrate table surfaces by forming (e.g., using Deep Reactive Ion Etching (DRIE), laser ablation, powder blasting, chemical etching, or another suitable technique) a trench around each burl, which reduces burl lateral stiffness and adds a vacuum volume to the volume between the substrate and the substrate table. In some aspects, the present disclosure provides a technique for optimizing burl geometry to better distribute stress in burls (e.g., by defining two or more different cone angles). In some aspects, the present invention provides a technique for varying the groove depth and stiffness (e.g., center-to-edge gradient (e.g., center stiff, edge compliant); localized per-burl optimization) of each burl across the core surface.

In some aspects, the invention provides for fabricating a substrate table that includes flexible burls for use in a DUV radiation system. In some aspects, the present invention provides for forming a core that includes a plurality of burls for supporting an object such as a wafer (e.g., burls may be provided on a top side of the core facing the wafer). The core may also include a plurality of grooves. Each of the plurality of burls may be surrounded by a respective groove of the plurality of grooves. In some aspects, such as where the substrate table is to be used in an EUV radiation system, the core may be configured to be connected to an electrostatic sheet comprising a plurality of apertures configured to receive the plurality of burls of the core such that the plurality of burls of the core are aligned with the plurality of apertures of the electrostatic sheet. In some aspects, the core may be configured to be connected to the electrostatic sheet using a vacuum sheet comprising a plurality of recesses configured to receive the plurality of burls of the core such that the plurality of burls of the core are further aligned with the plurality of recesses of the vacuum sheet.

The systems, apparatuses, methods, and computer program products disclosed herein have many exemplary aspects. For example, aspects of the present disclosure reduce lateral burl stiffness. Accordingly, aspects of the present disclosure provide: expanding in-plane wafer deformations and making them more correctable; reducing the impact of contact stiffness variation on overall stiffness, thus reducing sensitivity to burl wear and wafer backside variation; and reduced thermal slip, thereby enabling higher thermal doses, lower coefficients of static friction, or both.

In another example, aspects of the present disclosure provide for optimizing the behavior of vacuum pressure transients, also known as "vacuum volume adaptation," during wafer loading (e.g., when the distance between the substrate and the substrate table is locally changing) by: decoupling or partially decoupling the distance between the burls tops and the lowered planar height (e.g., the surface on which the burls are disposed) from the total volume between the substrate and the substrate table without changing the general above-surface geometry of the flexible burls (e.g., the height of the burls tops, pattern, and contact area).

Before these aspects are described in greater detail, however, it is instructive to present an example environment in which aspects of the invention may be implemented.

Example lithography System

FIGS. 1A and 1B are schematic illustrations of a lithographic apparatus 100 and a lithographic apparatus 100', respectively, in which aspects of the present disclosure may be implemented. As shown in fig. 1A and 1B, the lithographic apparatus 100 and 100 'are illustrated from a viewpoint (e.g., a side view) perpendicular to the XZ plane (e.g., the X axis points to the right, the Z axis points upward, and the Y axis points away from the viewer's page), while the patterning device MA and the substrate W are presented from an additional viewpoint (e.g., a top view) perpendicular to the XY plane (e.g., the X axis points to the right, the Y axis points upward, and the Z axis points out of the page toward the viewer).

In some aspects, lithographic apparatus 100 and lithographic apparatus 100' include one or both of the following structures: an illumination system IL (e.g., an illuminator) configured to condition a radiation beam B (e.g., a DUV radiation beam or an EUV radiation beam); a support structure MT (e.g. a mask table) configured to support a patterning device MA (e.g. a mask, reticle or dynamic patterning device) and connected to a first positioner PM configured to accurately position the patterning device MA; and a substrate holder, such as a substrate table WT (e.g. a wafer table), configured to hold a substrate W (e.g. a resist coated wafer) and connected to a second positioner PW configured to accurately position the substrate W. The lithographic apparatus 100 and 100' also have a projection system PS (e.g., a refractive projection lens system) configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g., a portion including one or more dies) of the substrate W. In lithographic apparatus 100, patterning device MA and projection system PS are reflective. In lithographic apparatus 100', patterning device MA and projection system PS are transmissive.

In some aspects, in operation, the illumination system IL may receive a radiation beam from a radiation source SO (e.g., via a beam delivery system BD shown in fig. 1B). The illumination system IL may include various types of optical structures, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic and other types of optical components, or any combination thereof, for directing, shaping, or controlling radiation. In some aspects, the illumination system IL may be configured to condition the radiation beam B to have a desired spatial intensity distribution and angular intensity distribution in its cross-section at the plane of the patterning device MA.

In some aspects, the support structure MT may hold the patterning device MA in a manner that depends on the orientation of the patterning device MA with respect to a reference frame, the design of at least one of the lithographic devices 100 and 100', and other conditions, such as for example whether or not the patterning device MA is held in a vacuum environment. The support structure MT may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device MA. The support structure MT may be, for example, a frame or a table, which may be fixed or movable as required. By using a sensor, the support structure MT may ensure that the patterning device MA is at a desired position, for example with respect to the projection system PS.

The term "patterning device" should be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section such as to create a pattern in a target portion C of the substrate W. The pattern imparted to the radiation beam B may correspond to a particular functional layer in a device being created in the target portion C to create an integrated circuit.

In some aspects, patterning device MA may be a transmissive patterning device (as in lithographic device 100' of fig. 1B) or a reflective patterning device (as in lithographic device 100 of fig. 1A). Patterning device MA may include various structures, such as a reticle, a mask, a programmable mirror array, a programmable LCD panel, other suitable structures, or a combination thereof. Masks include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. In one example, the programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so that an incoming radiation beam is reflected in different directions. Tilting the mirrors can impart a pattern in a radiation beam B which is reflected by a matrix of small mirrors.

The term "projection system" PS should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, anamorphic, electromagnetic, electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, and/or for other factors such as the use of an immersion liquid (e.g. over a substrate W), or the use of a vacuum. Since other gases may absorb too much radiation or electrons, a vacuum environment may be used for EUV or electron beam radiation. Thus, a vacuum environment can be provided to the entire beam path by means of the vacuum wall and the vacuum pump. In addition, in some aspects, any use of the term "projection lens" herein may be interpreted as synonymous with the more general term "projection system".

In some aspects, the lithographic apparatus 100 and/or the lithographic apparatus 100' may be of a type having two (dual stage) or more substrate tables or two or more mask tables. In such "multiple stage" machines the additional substrate tables WT may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other substrate tables WT are being used for exposure. In one example, a preparation step of a subsequent exposure of the substrate W may be performed on the substrate W located on one of the substrate tables WT, while another substrate W located on another of the substrate tables WT is being used to expose a pattern on that other substrate W. In some examples, the additional table may not be the substrate table WT.

In some aspects, the lithographic apparatus 100 and/or the lithographic apparatus 100' may comprise a measurement stage in addition to the substrate table WT. The measurement stage may be arranged to hold the sensor. The sensor may be arranged to measure a property of the projection system PS, a property of the radiation beam B, or both. In some aspects, the measurement stage can hold a plurality of sensors. In some aspects, the measurement stage may move under the projection system PS when the substrate table WT is remote from the projection system PS.

In some aspects, the lithographic apparatus 100 and/or the lithographic apparatus 100' may also be of a type wherein at least a portion of the substrate may be covered by a liquid of relatively high refractive index (e.g. water) so as to fill a space between the projection system PS and the substrate W. Immersion liquids may also be applied to other spaces in the lithographic apparatus, for example, between patterning device MA and projection system PS. Immersion techniques are used to increase the numerical aperture of projection systems. The term "immersion" as used herein does not mean that a structure, such as a substrate, must be submerged in liquid, but rather only means that liquid is located between the projection system and the substrate during exposure. Various immersion techniques are described in U.S. Pat. No. 6,952,253 entitled "LITHOGRPHIC APPARATUS AND DEVICE MANUFACTURING METHOD" issued at 10/4/2005, the entire contents of which are incorporated herein by reference.

Referring to fig. 1A and 1B, the illumination system IL receives a radiation beam from a radiation source SO. For example, when the source SO is an excimer laser, the source SO and the lithographic apparatus 100 or 100' may be separate physical entities. In such cases, the source SO is not considered to form part of the lithographic apparatus 100 or 100' and the radiation beam is passed from the source SO to the illumination system IL with the aid of a beam delivery system BD comprising, for example, suitable directing mirrors and/or a beam expander (e.g. as shown in FIG. 1B). In other cases, the source SO may be an integral part of the lithographic apparatus 100 or 100', for example when the source SO 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.

In some aspects, the illumination system IL may include an adjuster AD for adjusting the angular intensity distribution of the radiation beam. In general, at least an outer radial extent and/or an inner radial extent (commonly referred to as σ -outer and σ -inner, respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. IN addition, the illumination system IL may include various other components, such as an integrator IN and a radiation collector CO (e.g., a collector or collector optics). In some aspects, the illumination system IL may be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross-section.

Referring to fig. 1A, in operation, a radiation beam B may be incident on a patterning device MA (e.g., a mask, a reticle, a programmable mirror array, a programmable LCD panel, any other suitable structure, or a combination thereof), which may be held on a support structure MT (e.g., a mask table), and may be patterned by a pattern (e.g., a design layout) present on the patterning device MA. In the lithographic apparatus 100, the radiation beam B may be reflected from the patterning device MA. After having traversed the patterning device MA (e.g., after being reflected from the patterning device MA), the radiation beam B may pass through a projection system PS, which may focus the radiation beam B onto a target portion C of the substrate W or onto a sensor arranged at the stage.

In some aspects, the substrate table WT may be moved accurately (e.g. so as to position different target portions C in the path of the radiation beam B) by means of the second positioner PW and position sensor IFD2 (e.g. an interferometric device, linear encoder or capacitive sensor). Likewise, the first positioner PM and another position sensor IFD1 can be used to accurately position the patterning device MA with respect to the path of the radiation beam B.

In some aspects, the patterning device MA and the substrate W may be aligned using the mask alignment marks M1 and M2 and the substrate alignment marks P1 and P2. Although fig. 1A and 1B illustrate that the substrate alignment marks P1 and P2 occupy dedicated target portions, the substrate alignment marks P1 and P2 may be located in a space between the target portions. When the substrate alignment marks P1 and P2 are located between the target portions C, they are referred to as scribe-lane alignment marks. The substrate alignment marks P1 and P2 may also be arranged as intra-die marks in the target portion C area. These on-die marks may also be used as metrology marks, for example, for overlay measurements.

In some aspects, for purposes of illustration and not limitation, one or more of the figures herein may utilize a Cartesian coordinate system. The cartesian coordinate system includes three axes: an X axis, a Y axis and a Z axis. Each of the three axes is orthogonal to the other two axes (e.g., the X axis is orthogonal to the Y axis and the Z axis, the Y axis is orthogonal to the X axis and the Z axis, and the Z axis is orthogonal to the X axis and the Y axis). The rotation about the X-axis is called Rx rotation. The rotation about the Y-axis is referred to as Ry rotation. The rotation about the Z axis is referred to as Rz rotation. In some aspects, the X-axis and the Y-axis define a horizontal plane, while the Z-axis is in a vertical direction. In some aspects, the orientation of the cartesian coordinate system may be different, e.g., such that the Z-axis has a component along the horizontal plane. In some aspects, another coordinate system, such as a cylindrical coordinate system, may be used.

Referring to fig. 1B, a radiation beam B is incident on, and patterned by, a patterning device MA held on a support structure MT. After having traversed the patterning device MA, the radiation beam B passes through the projection system PS, which focuses the radiation beam onto a target portion C of the substrate W. In some aspects, the projection system may have a pupil that is conjugate to the illumination system pupil. In some aspects, portions of the radiation emanate from the intensity distribution at the illumination system pupil and traverse the mask pattern without being affected by diffraction at the mask pattern, and an image of the intensity distribution at the illumination system pupil is produced.

The projection system PS projects an image MP 'of the mask pattern MP onto a resist layer coated on the substrate W, wherein the image MP' is formed by a diffracted beam generated from the mask pattern MP by radiation from the intensity distribution. For example, the mask pattern MP may include an array of lines and spaces. Diffraction of radiation at the array and other than zero order diffraction generates a diverted diffracted beam having a change of direction along a direction perpendicular to the line. The reflected light (e.g., the zero-order diffracted beam) traverses the pattern in the propagation direction without any change. The zero-order diffracted beam traverses an upper lens or upper lens group of the projection system PS upstream of the pupil conjugate of the projection system PS to reach the pupil conjugate. The portion of the intensity distribution that lies in the plane of the pupil conjugate and that is associated with the zero-order diffracted beam is an image of the intensity distribution in the illumination system pupil of the illumination system IL. In some aspects, the aperture device is disposed at or substantially at a plane including the pupil conjugate of the projection system PS.

The projection system PS is arranged to capture not only the zero order diffracted beam, but also the first order diffracted beam or the first and higher order diffracted beams (not shown) by means of a lens or a lens group. In some aspects, dipole illumination for imaging a line pattern extending in a direction perpendicular to the line may be used to take advantage of the resolution enhancement effect of dipole illumination. For example, the first order diffracted beams interfere with the corresponding zero order diffracted beams at the level of the substrate W, while producing an image of the mask pattern MP with the highest possible resolution and process window (e.g., available depth of focus combined with allowable exposure dose bias). In some aspects, astigmatic aberration can be reduced by providing an emitter (not shown) in opposite quadrants of the illumination system pupil. Furthermore, in some aspects, astigmatic aberration can be reduced by blocking the zero order beam in a pupil conjugate of the projection system PS associated with the radiation poles in opposite quadrants. This is described in more detail in U.S. patent No. 7,511,799, entitled "LITHOGRAPHIC PROJECTION APPARATUS AND ADEVICE MANUFACTURING METHOD," issued 3/31/2009, the entire contents of which are incorporated herein by reference.

In some aspects, the substrate table WT may be moved accurately, e.g. with the aid of a second positioner PW and position measurement system PMS (e.g. comprising a position sensor, such as an interferometric device, linear encoder or capacitive sensor), e.g. so as to position different target portions C in a focused and aligned position in the path of the radiation beam B. Also, the first positioner PM and another position sensor (e.g. an interferometric device, linear encoder, or capacitive sensor) (which is not shown in FIG. 1B) can be used to accurately 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). Mask alignment marks M1 and M2 and substrate alignment marks P1 and P2 may be used to align patterning device MA and substrate W.

In general, the mobile support structure MT may be realized with the aid of a long-stroke positioner (coarse positioning) and a short-stroke positioner (fine positioning), which form part of the first positioner PM. Also, moving the substrate table WT may be realized using a long-stroke positioner and a short-stroke positioner, 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 mask alignment marks M1, M2 and the substrate alignment marks P1, P2. Although the substrate alignment marks (as illustrated) occupy dedicated target portions, they may be located in spaces between target portions (e.g., scribe-lane alignment marks). Also, in cases where more than one die is provided on patterning device MA, mask alignment marks M1 and M2 may be located between the dies.

The support structure MT and the patterning device MA can be located in a vacuum chamber V, in which an in-vacuum robot can be used to move a patterning device, such as a mask, into and out of the vacuum chamber. Alternatively, when the support structure MT and patterning device MA are located outside of a vacuum chamber, the vacuum external robot may be used in various transport operations, similar to an internal vacuum robot. In some examples, both the in-vacuum and out-of-vacuum robots need to be calibrated for smooth transfer of any payload (e.g., mask) to the stationary kinematic mount of the transfer station.

In some aspects, the lithographic apparatus 100 and 100' 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, while an entire pattern imparted to the radiation beam B is projected onto a target portion C at one time (e.g. a single static exposure). The substrate table WT is then offset in the X-direction and/or the Y-direction so that different target portions C can be exposed.

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

3. In another mode, the support structure MT is kept essentially stationary to hold a programmable patterning device MA, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C. The pulsed radiation source SO may be used and the programmable patterning device updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device MA, such as a programmable mirror array.

In some aspects, lithographic apparatus 100 and 100' may employ combinations and/or variations on the above described modes of use or entirely different modes of use.

In some aspects, as shown in FIG. 1A, a lithographic apparatus 100 includes an EUV source configured to generate an EUV radiation beam for EUV lithography. In general, the EUV source may be configured in a radiation source SO and the corresponding illumination system IL is configured to condition an EUV radiation beam B of the EUV source.

FIG. 2 depicts the lithographic apparatus 100 in more detail, the lithographic apparatus 100 comprising a radiation source SO (e.g., a source collector apparatus), an illumination system IL, and a projection system PS. As shown in FIG. 2, lithographic apparatus 100 is illustrated from a viewpoint (e.g., a side view) perpendicular to an XZ plane (e.g., with the X-axis pointing to the right and the Z-axis pointing upwards).

The radiation source SO is constructed and arranged such that a vacuum environment can be maintained within the enclosure 220. The radiation source SO comprises a source chamber 211 and a collector chamber 212, and is configured to generate and transmit EUV radiation. EUV radiation may be generated from a gas or vapor (e.g., xenon (Xe) gas, lithium (Li) vapor, or tin (Sn) vapor), wherein the EUV radiation-emitting plasma 210 is generated to emit radiation in the EUV range of the electromagnetic spectrum. The EUV radiation emitting plasma 210, which is at least partially ionized, may be generated by, for example, an electrical discharge or a laser beam. Partial pressures of, for example, about 10.0 pascals (Pa) of Xe gas, li vapor, sn vapor, or any other suitable gas or vapor may be used to efficiently generate radiation. In some aspects, a plasma of excited tin is provided to generate EUV radiation.

Radiation emitted by the EUV radiation emitting plasma 210 is transferred from the source chamber 211 to the collector chamber 212 via an optional gas barrier or contaminant trap 230 (also referred to as a contaminant barrier or foil trap in some cases), which gas barrier or contaminant trap 230 is positioned in or behind an opening in the source chamber 211. The contaminant trap 230 may include a channel structure. The contaminant trap 230 may also include a gas barrier or a combination of a gas barrier and a channel structure. The contaminant trap 230, also indicated herein, includes at least a channel structure.

The collector chamber 211 may include a radiation collector CO (e.g., a concentrator or collector optics), which may be a so-called grazing incidence collector. The radiation collector CO has an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation traversing the radiation collector CO may be reflected by the grating spectral filter 240 to be focused in the virtual source point IF. The virtual source point IF is often referred to as an intermediate focus and the source collector means is arranged such that the virtual source point IF is located at or near an opening 221 in the enclosure 220. The virtual source point IF is an image of the EUV radiation emitting plasma 210. The grating spectral filter 240 is particularly useful for suppressing Infrared (IR) radiation.

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

There may typically be more elements in the illumination system IL and the projection system PS than are shown. Alternatively, depending on the type of lithographic apparatus, there may be a grating spectral filter 240. Further, there may be more mirrors than those shown in fig. 2. For example, there may be 1 to 6 more reflective elements in the projection system PS than those shown in fig. 2.

The radiation collector CO as illustrated in fig. 2 is depicted as a nested collector with grazing incidence reflectors 253, 254 and 255, as just an example of a collector (or collector mirror). The grazing incidence reflectors 253, 254 and 255 are arranged axially symmetrically about the optical axis O and a radiation collector CO of this type is preferably used in combination with a discharge-generating plasma (DPP) source.

Example lithography Unit

FIG. 3 illustrates a lithography unit 300, sometimes referred to as a lithography unit or cluster. As shown in fig. 3, the lithography unit 300 is illustrated from a viewpoint (e.g., top view) perpendicular to the XY plane (e.g., with the X-axis pointing to the right and the Y-axis pointing upwards).

The lithographic apparatus 100 or 100' may form part of a lithographic cell 300. The lithography unit 300 may also include one or more devices to perform pre-exposure and post-exposure processes on the substrate. For example, these devices may include a spin coater SC for depositing a resist layer, a developer DE for developing the exposed resist, a chill plate CH, and a bake plate BK. The substrate handler RO (e.g., a robotic arm) picks up substrates from the input/output ports I/O1 and I/O2, moves them between different processing devices, and transfers them to the load station LB of the lithographic apparatus 100 or 100'. These devices, often collectively referred to as tracks, are under the control of a track control unit TCU, which itself is controlled by a supervisory control system SCS, which also controls the lithographic apparatus via a lithographic control unit LACU. Thus, different devices may be operated to maximize throughput and processing efficiency.

Example substrate stage

Fig. 4 shows a schematic illustration of an example substrate stage 400 in accordance with some aspects of the present disclosure. In some aspects, the example substrate stage 400 may include a substrate table 402, a support block 404, one or more sensor structures 406, any other suitable component, or any combination thereof. In some aspects, the substrate table 402 may include a chuck (e.g., wafer chuck, reticle chuck, electrostatic chuck) that holds the substrate 408. In some aspects, each of the one or more sensor structures 406 may include a Transmission Image Sensor (TIS) plate. The TIS plate is a sensor unit that includes one or more sensors and/or marks for use in a TIS sensing system for accurately positioning the wafer with respect to the position of a projection system (e.g., projection system PS described with reference to fig. 1A, 1B, and 2) and a mask (e.g., patterning device MA described with reference to fig. 1A, 1B, and 2) of a lithographic apparatus (e.g., lithographic apparatus 100 and lithographic apparatus 100' described with reference to fig. 1A, 1B, and 2). Although a TIS plate is shown herein for purposes of illustration, aspects herein are not limited to any particular sensor. The substrate table 402 is disposed on a support block 404. One or more sensor structures 406 are disposed on the support block 404.

In some aspects, when the example substrate stage 400 supports the substrate 408, the substrate 408 may be disposed on the substrate stage 402.

The terms "flat," "flatness," and the like may be used herein to describe structures that relate to the general plane of a surface. For example, a curved surface or a non-horizontal surface may be a surface that does not conform to a flat plane. The protrusions and recesses on the surface can also be characterized as deviating from a "flat" plane.

The terms "smooth", "roughness" and the like may be used herein to refer to localized variations, microscopic deviations, granularity or texture of a surface. For example, the term "surface roughness" may refer to the microscopic deviation of a surface profile from an average line or plane. Deviations are typically measured (in length) as amplitude parameters such as Root Mean Square (RMS) or arithmetic mean deviation (Ra) (e.g., 1nm RMS).

In some aspects, the surface of the substrate table mentioned above (e.g. substrate table WT in fig. 1A and 1B, substrate table 402 in fig. 4) may be planar or with burls. When the surface of the substrate table is flat, any particles or contaminants adhering between the substrate table and the wafer may cause the contaminants to strike the wafer, causing lithographic errors in its vicinity. Thus, the contaminants reduce device yield and increase production costs.

Providing burls on the substrate table helps to reduce the undesirable effects of a flat substrate table. When the wafer is clamped to the substrate table with burls, empty space is obtained in the area where the wafer does not contact the substrate table. The empty space serves as a pocket for contaminants to prevent printing errors. Another advantage is that contaminants located on the burls are more likely to be crushed due to the increased load caused by the burls. Breaking up the contaminants also helps to mitigate strike-through errors. In some aspects, the combined surface area of the burls may be approximately 1% to 5% of the surface area of the substrate table. As used herein, the surface area of a burl refers to the surface that is in contact with the wafer (e.g., does not include a sidewall); the surface area of the substrate table refers to the span of the surface of the substrate table in which burls are present (e.g., not including the side or back of the substrate table). When the wafer is clamped to a substrate table with burls, the load is increased 100 times compared to a flat substrate table, which is sufficient to crush most contaminants. Although the examples herein use a substrate table, the examples are not intended to be limiting. For example, aspects of the disclosure may be implemented on reticle stages of a variety of clamping structures (e.g., electrostatic clamps, clamping films) and a variety of lithography systems (e.g., DUV, EUV).

In some aspects, the burl-to-wafer interface governs the functional performance of the substrate table. When the surface of the substrate table is smooth, adhesion may be created between the smooth surface of the substrate table and the smooth surface of the wafer. The phenomenon in which two smooth surfaces in contact adhere together is called cling. The close fit may cause problems (e.g., overlay problems) in device fabrication due to high friction and planar stresses in the wafer (it is optimal to have the wafer slide easily during alignment).

Example substrate stage

Fig. 5 is a schematic illustration of portions of an example EUV substrate table 500, according to some aspects of the present disclosure. It should be appreciated that the illustrated portion of the example EUV substrate table 500 may be used outside of EUV applications. For example, the illustrated portion of the example EUV substrate table 500 may be used in DUV applications, and in some aspects, the electrostatic sheet 530 may be omitted or otherwise not included.

As shown in fig. 5, an example EUV substrate table 500 may include a core 510 and an electrostatic sheet 530. In some aspects, the electrostatic sheet 530 may be mounted to the core 510 using a vacuum sheet 520.

Fig. 6A, 6B, and 6C are cross-sectional illustrations of portions of an example EUV substrate stage 600 according to some aspects of the present disclosure. It should be appreciated that the illustrated portion of the example EUV substrate table 600 may be used outside of EUV applications. For example, the illustrated portion of the example EUV substrate stage 600 may be used in DUV applications, and in some aspects, the electrostatic sheet 630 may be omitted or otherwise not included.

As shown in fig. 6A, an example EUV substrate stage 600 may include a core 610 and an electrostatic sheet 630. In some aspects, the electrostatic sheet 630 may be mounted to the core 610 using a vacuum sheet 620.

In some aspects, the core 610 may include a plurality of burls 612 (e.g., glass burls, hard burls, flexible burls, or any other suitable burls). In some aspects, the plurality of burls 612 may be configured to support an object such as a wafer (e.g., the plurality of burls 612 may be disposed on a top side of the core 610 facing the wafer). In some aspects, the difference in the respective heights of each of the plurality of burls 612 may result in the core 610 having a non-flatness as shown by burl top height differences 614 and 616. In some aspects, the vacuum tab 620 may include a plurality of vacuum connections (not shown) and a plurality of recesses 622 configured to receive the plurality of nubs 612. In some aspects, the plurality of recesses 622 may have a recess depth 624 of between about 8.00 microns +/-0.25 microns and about 20.00 microns +/-0.25 microns. In some aspects, the electrostatic plate 630 may include a plurality of apertures 632 configured to receive the plurality of burls 612. In some aspects, the electrostatic plate 630 may be configured to be connected to the vacuum plate 620 such that the plurality of apertures 632 are aligned with the plurality of recesses 622.

In some aspects, at least a portion of core 610 may be formed of SiSiC or SiC. In some aspects, at least a portion of the plurality of nubs 612 can be formed of SiSiC, siC, DLC, alN, siN or CrN. In some aspects, at least a portion of the vacuum sheet 620 may be formed of fused silica. In some aspects, at least a portion of the electrostatic sheet 630 may be formed from borosilicate glass. In some aspects, at least another portion of the electrostatic sheet 630 may be formed of a conductive material. In some aspects, the electrostatic sheet 630 may include one or more electrodes sandwiched between two or more dielectric layers (such as two glass wafers). In some aspects, the stiffness of the core 610 may be greater than the stiffness of the vacuum sheet 620, and the stiffness of the vacuum sheet 620 may be greater than the stiffness of the electrostatic sheet 630. For example, the electrostatic sheet 630, the vacuum sheet 620, or both may have flexibility sufficient to conform to the non-flatness of the core 610.

In some aspects, the plurality of recesses 622 may be formed by patterning and etching the vacuum plate 620 based on a pattern (e.g., number, spacing, location, etc.) of the plurality of burls 612, a pattern of the plurality of apertures 632, or a pattern of both. Additionally or alternatively, in some aspects, the plurality of recesses 622 can be formed by depositing a metal layer (e.g., cu, crN) on the vacuum plate 620 and then patterning and etching the deposited metal layer based on the pattern of the plurality of burls 612, the pattern of the plurality of apertures 632, or both. In some aspects, the plurality of apertures 632 may be formed by patterning and etching the electrostatic sheet 630 based on the pattern of the plurality of burls 612, the pattern of the plurality of recesses 622, or both. In some aspects, the plurality of apertures 632 may be formed by drilling the electrostatic sheet 630 based on the pattern of the plurality of burls 612, the pattern of the plurality of recesses 622, or both.

In some aspects, as indicated by arrow 692, the vacuum plate 620 may be configured to vacuum clamp the electrostatic plate 630 to the vacuum plate 620 in response to applying vacuum to the plurality of vacuum connections of the vacuum plate 620. Additionally or alternatively, in some aspects, the vacuum plate 620 may include an electrode layer (e.g., cu or CrN) containing one or more electrodes, and the vacuum plate 620 may be configured to electrostatically clamp the electrostatic plate 630 to the vacuum plate 620 in response to applying one or more voltages to one or more of the one or more electrodes of the electrode layer of the vacuum plate 620. In one example, when the electrode of the electrostatic plate 630 is not grounded, the example EUV substrate stage 500 may include two electrodes for electrostatically clamping the electrostatic plate 630 to the vacuum plate 620, one electrode at a negative potential and the other electrode at a positive potential. In another example, the example EUV substrate table 500 may include one electrode for electrostatically clamping the electrostatic plate 630 to the vacuum plate 620 when the electrode of the electrostatic plate 630 is grounded.

In some aspects, the vacuum plate 620 may include a coating disposed on at least a portion of a surface of the vacuum plate 620 facing the electrostatic plate 630 (e.g., at least in an area where the vacuum plate 620 and the electrostatic plate 630 touch when the electrostatic plate 630 is clamped to the vacuum plate 620). In some aspects, the properties of the coating may be configured to substantially prevent optical contact or other strong or substantially permanent adhesion between the vacuum sheet 620 and the electrostatic sheet 630. In some aspects, at least a portion of the coating may be formed of CrN or DLC.

In some aspects, as indicated by arrow 694, the vacuum plate 620 may be configured to vacuum clamp the core 610 to the electrostatic plate 630 and the vacuum plate 620 in response to applying vacuum to the plurality of vacuum connections of the vacuum plate 620. Additionally or alternatively, in some aspects, the electrostatic sheet 630 may be configured to be bonded to the core 610 using an adhesive (e.g., one or more glue sites).

As shown in fig. 6B, the vacuum plate 620 is connected to the electrostatic plate 630 such that the plurality of apertures 632 are aligned with the plurality of recesses 622. In some aspects, the vacuum plate 620 may be partially or entirely connected to the electrostatic plate 630 through a plurality of connection regions 623, and the connection regions 623 may include a plurality of vacuum chambers.

As shown in fig. 6C, the electrostatic sheet 630 and the vacuum sheet 620 are connected to the core 610 such that the vacuum sheet 620 and the electrostatic sheet 630 conform to the non-flatness of the core 610. In some aspects, once the manufacturing process is complete, the vacuum sheet 720 may be removed from the core 610 and the electrostatic sheet 630.

Fig. 7 is a cross-sectional view of a portion of an example EUV substrate table fabrication system 700, according to some aspects of the present disclosure. It should be appreciated that the example EUV substrate table manufacturing system 700 may be used in applications other than EUV. In some aspects, an example EUV substrate table 701 may include a core 710, a vacuum sheet 720, and an electrostatic sheet 730. In some aspects, the core 710 may be mounted to the electrostatic sheet 730 using a vacuum sheet 720. In some aspects, an example EUV substrate stage 701 may be placed on a compliant layer 740 disposed on stage 750. In some aspects, the example EUV substrate table 701 may be placed under a plurality of weights 780 (e.g., steel plates placed on the core 710; or in some aspects, electromechanical forces) configured to maintain the core 710 pressed into the compliant layer 740. In some aspects, once the fabrication process is complete, the plurality of weights 780 may be removed from the example EUV substrate stage 701, and the example EUV substrate stage 701 may be removed from the vacuum sheet 720 and the compliant layer 740.

In some aspects, the core 710 may include a plurality of burls 712 (e.g., glass burls, hard burls, flexible burls, or any other suitable burls), the plurality of burls 712 configured to connect with the vacuum panel 720. In some aspects, the plurality of burls 712 can be configured to support an object such as a wafer (e.g., the plurality of burls 712 can be disposed on a top side of the core 710 and configured to face the wafer during operation of the lithographic apparatus). In some aspects, the core 710 may further include a plurality of burls 713 (e.g., glass burls, hard burls, flexible burls, or any other suitable burls), the plurality of burls 713 configured to support a substrate (e.g., a weighted substrate). In some aspects, the vacuum plate 720 may include a plurality of vacuum connections 723 and a plurality of recesses configured to receive the plurality of burls 712 (e.g., formed by etching the annular ring 721 to a depth of between about 8.00 microns +/-0.25 microns and about 20.00 microns +/-0.25 microns at each burl location). In some aspects, the plurality of recesses may have a recess depth of between about 8.00 microns +/-0.25 microns and about 20.00 microns +/-0.25 microns. In some aspects, the electrostatic patch 730 may include a plurality of apertures configured to receive the plurality of nubs 712. In some aspects, the electrostatic sheet 730 may be configured to be connected to the vacuum sheet 720 such that a plurality of apertures of the electrostatic sheet 730 are aligned with a plurality of recesses of the vacuum sheet 720.

In some aspects, at least a portion of core 710 may be formed of SiSiC or SiC. In some aspects, at least a portion of the plurality of nubs 712 can be formed from SiSiC, siC, DLC, alN, siN or CrN. In some aspects, at least a portion of the plurality of nubs 713 may be formed of SiSiC, siC, DLC, alN, siN or CrN. In some aspects, at least a portion of the vacuum sheet 720 may be formed of fused silica. In some aspects, at least a portion of the electrostatic sheet 730 may be formed from borosilicate glass. In some aspects, at least another portion of the electrostatic patch 730 may be formed of a conductive material. In some aspects, the electrostatic sheet 730 may include one or more electrodes sandwiched between two or more dielectric layers (such as two glass wafers). In some aspects, compliant layer 740 can be or include a flexible support structure formed from: PDMS; soft low durometer polymers, such as 20A durometer silicones; any other suitable material; or any combination thereof.

In some aspects, the stiffness of the core 710 may be greater than the stiffness of the vacuum sheet 720, and the stiffness of the vacuum sheet 720 may be greater than the stiffness of the electrostatic sheet 730. For example, the electrostatic sheet 730, the vacuum sheet 720, or both may have sufficient flexibility to conform to the non-flatness of the core 710.

In some aspects, compliant layer 740 and mesa 750 may include one or more apertures (e.g., holes) for an alignment system (e.g., vision alignment system 760a, vision alignment system 760 b) to view (e.g., image, capture) alignment marks 725a disposed on core 710 and alignment marks 725b disposed on electrostatic patch 730.

In some aspects, the plurality of recesses of the vacuum plate 720 may be formed by patterning and etching the vacuum plate 720 based on a pattern (e.g., number, pitch, location, etc.) of the plurality of burls 712, a pattern of the plurality of apertures of the electrostatic plate 730, or a pattern of both. Additionally or alternatively, in some aspects, the plurality of recesses of the vacuum plate 720 may be formed by depositing a metal layer (e.g., cu, crN) on the vacuum plate 720 and then patterning and etching the deposited metal layer based on the pattern of the plurality of burls 712, the pattern of the plurality of apertures of the electrostatic plate 730, or both.

In some aspects, the plurality of apertures of the electrostatic sheet 730 may be formed by patterning and etching the electrostatic sheet 730 based on the pattern of the plurality of nubs 712, the pattern of the plurality of recesses of the vacuum sheet 720, or both. In some aspects, the plurality of apertures of the electrostatic sheet 730 may be formed by drilling the electrostatic sheet 730 based on the pattern of the plurality of nubs 712, the pattern of the plurality of recesses of the vacuum sheet 720, or both.

In some aspects, the electrostatic patch 730 may be configured to be bonded to the core 710 using a plurality of adhesive structures 734 (e.g., a plurality of glue sites applied to the electrostatic patch 730).

In some aspects, the vacuum sheet 720 may be configured to: in response to applying vacuum to the plurality of vacuum connections 723 of the vacuum plate 720, the electrostatic plate 730, the core 710, or both are vacuum clamped to the vacuum plate 720. Additionally or alternatively, in some aspects, the vacuum sheet 720 may include an electrode layer (e.g., cu or CrN), and the vacuum sheet 720 may be configured to: in response to applying a voltage to the electrode layer of the vacuum plate 720, the electrostatic plate 730, the core 710, or both are electrostatically clamped to the vacuum plate 720. In some aspects, the electrostatic sheet 730 and the vacuum sheet 720 may be connected to the core 710 such that the vacuum sheet 720 and the electrostatic sheet 730 conform to the non-flatness of the core 710.

In some aspects, the vacuum plate 720 may be connected to the electrostatic plate 730 and the core 710 such that the plurality of apertures of the electrostatic plate 730 and the plurality of nubs 712 of the core 710 are aligned with the plurality of recesses of the vacuum plate 720. In some aspects, the vacuum plate 720, the electrostatic plate 730, or both may include a plurality of electronic pin holes configured to receive a plurality of electronic pins 770. In some aspects, the vacuum plate 720 may also be connected to the electrostatic plate 730 and the core 710 such that a subset of the plurality of electronic pin holes are aligned with the plurality of electronic pins 770.

Fig. 8 is a cross-sectional illustration of a portion of another example EUV substrate table fabrication system 800 in accordance with some aspects of the present disclosure. It should be appreciated that the example EUV substrate table manufacturing system 800 may be used in applications other than EUV. In some aspects, an example EUV substrate stage 801 may include a core 810, an electrostatic sheet 830. In some aspects, the core 810 may be mounted to the electrostatic sheet 830 using a metal layer 820, the metal layer 820 being formed on a compliant layer 740, the compliant layer 740 being formed on a substrate 851. In some aspects, the example EUV substrate stage 801 may be placed under a plurality of weights 880 (e.g., steel plates placed on the core 710; or in some aspects, electromechanical forces) configured to maintain the core 810 pressed into the compliant layer 840. In some aspects, the force applied by the plurality of weights 880 may be adjusted to modify the height of the metal layer 820. In some aspects, once the fabrication process is complete, the plurality of weights 880 may be removed from the example EUV substrate stage 801.

In some aspects, the core 810 can include a plurality of burls 812 (e.g., glass burls, hard burls, flexible burls, or any other suitable burls) configured to connect with the compliant layer 840. In some aspects, the plurality of burls 812 can be configured to support an object such as a wafer (e.g., the plurality of burls 812 can be disposed on a top side of the core 810 and configured to face the wafer during operation of the lithographic apparatus). In some aspects, the core 810 may further include a plurality of burls 813 (e.g., glass burls, hard burls, flexible burls, or any other suitable burls) configured to support a substrate (e.g., a weighted substrate).

In some aspects, the substrate 851 may include a plurality of vacuum connections 823 (e.g., formed by patterning and etching or any other suitable technique or combination of techniques). In some aspects, the compliant layer 840 can include a plurality of vacuum connections (e.g., formed by patterning and etching or any other suitable technique or combination of techniques) configured to align with the plurality of vacuum connections 823 of the substrate 851.

In some aspects, the metal layer 820 may include a plurality of apertures (e.g., formed by patterning the metal layer 820 to form a plurality of annular metal rings, wherein each annular metal ring surrounds a respective burl and has a height of between about 8.00 microns +/-0.25 microns and about 20.00 microns +/-0.25 microns) configured to receive the plurality of burls 812. In some aspects, the plurality of apertures of the metal layer 820 may be formed by depositing a metal layer (e.g., cu, crN) on the compliant layer 840 and then patterning and etching the deposited metal layer based on the pattern (e.g., number, pitch, location, etc.) of the plurality of burls 812, the pattern of the plurality of apertures of the electrostatic sheet 830, or both.

In some aspects, the electrostatic sheet 830 may include a plurality of apertures configured to receive the plurality of burls 812. In some aspects, the electrostatic sheet 830 may be configured to be connected to the metal layer 820 such that a plurality of apertures of the electrostatic sheet 830 are aligned with a plurality of apertures of the metal layer 820. In some aspects, the plurality of apertures of the electrostatic sheet 830 may be formed by patterning and etching the electrostatic sheet 830 based on the pattern of the plurality of burls 812, the pattern of the plurality of apertures of the metal layer 820, or both. In some aspects, the plurality of apertures of the electrostatic sheet 830 may be formed by drilling the electrostatic sheet 830 based on the pattern of the plurality of burls 812, the pattern of the plurality of apertures of the metal layer 820, or both.

In some aspects, at least a portion of core 810 may be formed of SiSiC. In some aspects, at least a portion of the plurality of burls 812 can be formed of DLC, alN, siN or CrN. In some aspects, at least a portion of the plurality of burls 813 may be formed of DLC, alN, siN or CrN. In some aspects, at least a portion of the metal layer 820 may be formed of Cu or CrN. In some aspects, at least a portion of the electrostatic sheet 830 may be formed from borosilicate glass. In some aspects, at least another portion of the electrostatic sheet 830 may be formed of a conductive material. In some aspects, the electrostatic sheet 830 may include one or more electrodes sandwiched between two or more dielectric layers (such as two glass wafers). In some aspects, compliant layer 840 can be or include a flexible support structure formed from: PDMS; soft low durometer polymers, such as durometer 20A silicone; any other suitable material; or any combination thereof. In some aspects, at least a portion of the substrate 851 can be formed of fused silica. In some aspects, the substrate 851 can be any suitable substrate, such as a glass wafer.

In some aspects, the stiffness of the core 810 may be greater than the stiffness of the electrostatic sheet 830. In some aspects, the stiffness of the core 810 may be greater than the stiffness of the compliant layer 840. For example, the electrostatic sheet 830, compliant layer 840, or both may have sufficient flexibility to conform to the non-flatness of the core 810. In some aspects, the electrostatic sheet 830 may be configured to be bonded to the core 810 using a plurality of adhesive structures 834 (e.g., a plurality of glue sites applied to the electrostatic sheet 830).

In some aspects, the substrate 851 may be configured to: in response to applying vacuum to the plurality of vacuum connections 823 of the substrate 851, the electrostatic sheet 830, the core 810, or both are vacuum clamped to the metal layer 820, the compliant layer 840, and the substrate 851. Additionally or alternatively, in some aspects, the metal layer 820 may be configured to: in response to applying a voltage to the metal layer 820, the electrostatic sheet 830, the core 810, or both are electrostatically clamped to the metal layer 820, the compliant layer 840, and the substrate 851. In some aspects, the electrostatic sheet 830, the metal layer 820, the compliant layer 840, and the substrate 851 may be connected to the core 810 such that the compliant layer 840 and the electrostatic sheet 830 conform to the non-planarity of the core 810.

In some aspects, the metal layer 820 and the compliant layer 840 may be connected to the electrostatic sheet 830 and the core 810 such that the plurality of apertures of the electrostatic sheet 830 and the plurality of burls 812 of the core 810 are aligned with the plurality of apertures of the metal layer 820. In some aspects, the electrostatic sheet 830, compliant layer 840, substrate 851, or a combination thereof, may include a plurality of electronic pin holes configured to receive a plurality of electronic pins 870. In some aspects, the metal layer 820 and the compliant layer 840 may also be connected to the electrostatic sheet 830 and the core 810 such that a subset of the plurality of electronic pin holes are aligned with the plurality of electronic pins 870.

Exemplary nubs surrounded by grooves

Fig. 9A, 9B, 9C, 9D, 9E, 9F, and 9G are cross-sectional illustrations of an example burl (referred to herein as a "flexible burl") surrounded by an example groove, in accordance with some aspects of the present disclosure. In some aspects, the example flexible burls shown in fig. 9A, 9B, 9C, 9D, 9E, 9F, and 9G may be incorporated into any of the example substrate tables disclosed herein, such as onto a top surface, a bottom surface, or both of the example cores.

As shown in fig. 9A, in some aspects, an example flexible burls 900 can include burls 902, the burls 902 being surrounded by grooves 904 formed in a core 906. In some aspects, the trench 904 may be formed around the burls 902, for example, using Deep Reactive Ion Etching (DRIE), laser ablation, powder blasting, chemical etching, or another suitable technique. In one placeIn some aspects, the trench 904 may be etched directly into the core 906, into one or more layers disposed on the core 906, or a combination thereof. In some aspects, one or more portions of the burls 902 may be formed of SiSiC, siC, DLC, alN, siN or CrN. In some aspects, the burls 902 can have a top diameter of about 100 microns to about 500 microns. For example, burls 902 may have a top diameter of about 210 microns. In some aspects, the nubs 902 can have less than about 10 ⁷ Nm ^-1 Is a part of the stiffness of the steel sheet.

As shown in fig. 9B, in some aspects, an example flexible burls 920 may include burls 922, the burls 922 surrounded by grooves 924 formed in a core 926. In some aspects, the top of the nub 922 may be disposed at about height level a, the non-nub surface of the core 926 may be disposed at about height level B, and the bottom of the groove 924 may be disposed at about height level C. In some aspects, nubs 922 may have a profile f (z) as a function of height z, which profile f (z) may be optimized for stiffness and robustness while meeting requirements for nub top contact area and volume footprint. In some aspects, the profile f (z) may increase the burl width toward the bottom of burl 922 (e.g., height level C) and decrease the burl width toward the top of burl 922 (e.g., height level a). In one illustrative and non-limiting example, the nub 922 may have a first taper angle α toward the top of the nub 922 ₁ And a second taper angle alpha toward the bottom of the nub 922 ₂ Wherein the first taper angle alpha ₁ With a second cone angle alpha ₂ Different. In some aspects, one or more portions of the nub 922 may have a profile f (z) that includes one or more discrete steps (e.g., rather than a continuous taper angle).

In some aspects, the substrate-to-substrate table distance a-B may range from about 10.0 microns to greater than 1.0 mm. In some aspects, the length of nubs 922 (e.g., distances a-C) may range from about 10.0 microns to greater than 1.0mm (e.g., from about 100 microns to about 2.5 mm). In some aspects, the depth of the trench 944 (e.g., distance B-C) may be in the range from about 50.0 microns to greater than 1.0mm (e.g., from about 100 microns to about 2.5 mm). In one illustrative and non-limiting example, the substrate-to-substrate table distance A-B may be about 10 microns, the height of the nubs 922 (e.g., distance A-C) may be about 100 microns, and the depth of the grooves 924 (e.g., distance B-C) may be about 90 microns.

As shown in fig. 9C, in some aspects, an example flexible nub 940 may include a nub 942, the nub 942 being surrounded by a groove 944 formed in the core 946. In some aspects, the depth, width, shape, or combination thereof of the groove 944 can be tailored to generate a desired lateral burl stiffness and vacuum volume. For example, fig. 9C shows a representative, not-to-scale illustration of the design freedom of the vacuum volume (i.e., white area) between the substrate at level a and the substrate table at level B, without changing the stiffness of the burls 942. In some aspects, different substrate-to-substrate table distances a-B (e.g., from about 10.0 microns to greater than 1.0 microns) may be obtained while maintaining the vacuum volume substantially the same. For example, the first substrate to substrate table distance A-B ₁ May provide a distance A-B from the second substrate to the substrate table ₂ Substantially the same vacuum volume, wherein the trough 944 is at a level of B ₁ The width when associated is greater than the width of the channel 944 at the height level B ₂ Width at time of association.

Fig. 10A is an example graph 1000 showing an example in-plane deformation delta (in nanometers (nm)) of a substrate as a function of radius (in millimeters (mm)) and stiffness (σ, in N/m) for an example 300mm diameter wafer having an arcuate deformation of 200 microns. Fig. 10B is an example graph 1020 showing example in-plane deformation increments of a substrate with different coefficients of friction and stiffness as a function of radius for another example 300mm diameter wafer with 200 micron umbrella deformation.

Referring now to fig. 9D, 9E, 9F, and 9G, in some aspects, to achieve a laterally compliant burl with high vertical stiffness (e.g., a ratio between vertical stiffness and lateral stiffness of 1000 x), an elongated rod shape may be used instead of a cone. However, in some aspects, such an elongate rod may not be able to withstand external forces exerted on the burls. In some aspects, the "end of travel" (e.g., the portion of the core that forms the outer annulus of the groove surrounding the burls) may be used to prevent the burls from bending too far, resulting in burls breaking. In some aspects, the end of travel may be used to stabilize the laterally compliant nubs against external forces (e.g., polishing, cleaning, handling, etc.).

In some aspects, the gap between the burls and the end of travel of the core may be selected such that the burls do not touch the end of travel during wafer loading. In some aspects, the maximum displacement may occur during loading of the umbrella-shaped wafer. In some aspects, the displacement on the last burl may be approximately 0.5 μm per 100 μm warp. As a result, the gap between the burls and the end of travel may be at least a few microns. In some aspects, the maximum deflection of the elongate rod may be determined as shown in equation 1 below:

where σ represents the yield stress and E represents the Young's modulus. For an elongated rod, the vertical stiffness C can be defined for a cantilever beam using Euler-Bernoulli beam theory _z And lateral stiffness C _lat As shown in the following equation 2:

from this example of equation 2, it follows that the dimensions of the elongated rod can be freely chosen as long as the ratio L/d is approximately equal to 13.7.

As shown in FIG. 9D, in some aspects, a perspective view of a portion of an example substrate table 960 may include a burl 962 (e.g., 15 burls), the burl 962 being surrounded by a groove 964 formed in a core 966. In some aspects, the length L of each of the nubs 962 may be about 1500 μm, the diameter d of each of the nubs 962 may be about 110 μm, and the gap between each of the nubs 962 and each end of travel 965 of the core 966 may be about 9 μm. In some aspects, each nub may have a vertical stiffness of about 7e5N/m and a lateral stiffness of about 7e2N/m, resulting in a vertical stiffness to lateral stiffness ratio of about 1000:1. In some aspects, the combined lateral stiffness of nubs 962 may be about 1e4N/m and the combined vertical stiffness may be about 1e7N/m.

As shown in fig. 9E, in some aspects, an example flexible nub 970 may include a nub 972, the nub 972 being surrounded by a groove 974 (e.g., a deep, narrow groove) formed in the core 976. In some aspects, the length L (e.g., distance a-C) of the nubs 972 may be about 1500 μm, the diameter d of each of the nubs 972 may be about 110 μm, and the gap between the nubs 972 and the end of travel 975 of the core 976 may be about 9 μm. In some aspects, the vertical stiffness of the nub 972 may be about 7e5N/m and the lateral stiffness may be about 7e2N/m, resulting in a ratio of vertical stiffness to lateral stiffness of about 1000:1.

As shown in fig. 9F, in some aspects, an example flexible nub 980 may include a nub 982, the nub 982 being formed by a groove 984 (e.g., surface B) formed in the core 986 ₂ Shallow and narrow trenches nearby followed by deep and wide trenches). In some aspects, the gap between the nub 982 and the end of travel 985 of the core 986 may be about 9 μm near the top of the nub 982 (e.g., from distance B ₂ -B ₁ Corresponding to) and may be wider near the middle and bottom of nub 982 (e.g., from distance B) ₁ -C corresponds).

As shown in fig. 9G, in some aspects, an example flexible burls 990 may include burls 992, the burls 992 being surrounded by filaments 994 (e.g., nonlinear elastic filaments) formed in a core 996. In some aspects, the example flexible nubs 990 may be formed by: (i) creating a wide groove around the burl 992 with low tolerance; and (ii) filling the trench with an elastic filament. In some aspects, the filaments 994 may have a low stiffness during the first micrometer stroke. When the nubs are bent, the filaments 994 may become compressed, which may increase the stiffness of the filaments 994. In some aspects, the filaments 994 may have a nonlinear elasticity sufficient to prevent the nubs 992 from breaking.

In some aspects, fig. 10A and 10B illustrate one-dimensional (1D) simulation results of dynamically loading a wafer onto an example EUV wafer chuck. The plotted in-plane deformations may be increments of zero coefficient of friction (e.g., cof=0) and show that WLG has a lower spatial frequency for more flexible burls (e.g., σ=1e6n/m) and an amplitude similar to more rigid burls (e.g., σ=1e7n/m). As a result, WLG of a more flexible burls can be better corrected than a more rigid burls. In some aspects, the results also show less dependence on CoF.

11A and 11B are plan and cross-sectional illustrations of an example substrate table surface including example burls surrounded by example grooves, according to some aspects of the disclosure. FIG. 11A depicts a plan view (e.g., top view) of a portion of an example substrate table 1100. FIG. 11B shows a cross section through a portion of an example substrate table 1100 from the center to the edge (e.g., 0.ltoreq.r.ltoreq.150 mm) of a core 1110.

As shown in FIGS. 11A and 11B, an example substrate table 1100 may include a plurality of flexible burls formed in or on a core 1110 (e.g., a top surface or a bottom surface of a core having a diameter of about 300 mm). The plurality of flexible burls may include, for example, 30000 flexible burls. In some aspects, each flexible burl may be about 175 microns high and have a top diameter of about 210 microns. In some aspects, the pitch between the flexible burls can be about 1.5mm.

In some aspects, the height difference between the surface of the core 1110 and the top of each of the plurality of burls (e.g., the substrate-to-substrate table distance a-B) may be substantially constant across the core 1110, while the height difference between the bottom of each of the plurality of grooves and the top of each of the plurality of burls may vary across the core 1110. For example, the trench depth B-C may increase as the distance r increases from the center of the core 1110. Thus, in some aspects, the length and stiffness of each of the plurality of burls may vary across the core 1110 without altering the height of the top of the plurality of burls above the surface of the core 1110. For example, as distance r increases from the center of core 1110, burl length a-C may increase and burl stiffness may decrease. In other words, the burls disposed in the peripheral region of the core 1110 may have a greater length and a lower stiffness than the burls disposed in the central region of the core 1110. In some aspects, the burls disposed near the periphery of the core 1110 may have a lower stiffness such that less force may be used to displace the burls to more easily follow the expanding surface of the substrate due to thermal loading.

In some aspects, the plurality of flexible burls can include a first subset of flexible burls surrounded by a first subset of grooves, such as burls 1102 surrounded by grooves 1104, in a first region I (e.g., a central region). In some aspects, the plurality of flexible knuckles can include a second subset of knuckles surrounded by a second subset of grooves, such as knuckles 1122 surrounded by grooves 1124, in a second region II (e.g., a middle region). In some aspects, the plurality of flexible nubs may include a third subset of nubs surrounded by a third subset of grooves, such as nubs 1142 surrounded by grooves 1144, in a third region III (e.g., a peripheral region).

In some aspects, the depth of each trench in the first subset of trenches in the first region I may be less than the depth of each trench in the second subset of trenches in the second region II. In some aspects, the depth of each trench in the second subset of trenches in the second region II may be less than the depth of each trench in the third subset of trenches in the third region III. For example, the depth 1105 (e.g., distance B-C) of the trench 1104 in the first region I ₁ ) Possibly less than the depth 1125 of the trench 1124 in the second region II (e.g., distance B-C ₂ ) And the depth 1125 of the trench 1124 in the second region II may be less than the depth 1145 of the trench 1144 in the third region III (e.g., distance B-C ₃ )。

In some aspects, each burl in the first subset of burls in the first region I may be longer than each burl in the second subset of burls in the second region IIThe length of the burls. In some aspects, the length of each burl in the second subset of burls in the second region II may be greater than the length of each burl in the third subset of burls in the third region III. For example, the length 1103 of the burls 1102 in the first region I (e.g., distance A-C ₁ ) May be greater than the length 1123 of the burls 1122 in the second region II (e.g., distance A-C ₂ ) And the length 1123 of the burls 1122 in the second region II may be greater than the length 1143 of the burls 1142 in the third region III (e.g., distances A-C ₃ )。

In some aspects, the stiffness of each burl in the first subset of burls in the first region I may be greater than the stiffness of each burl in the second subset of burls in the second region II. In some aspects, the stiffness of each burl in the second subset of burls in the second region II may be greater than the stiffness of each burl in the third subset of burls in the third region III. For example, the stiffness of the burls 1102 in the first region I may be greater than the stiffness of the burls 1122 in the second region II, and the stiffness of the burls 1122 in the second region II may be greater than the stiffness of the burls 1142 in the third region III.

Example manufacturing Process of device

Fig. 12 is an example method 1200 of manufacturing a device according to some aspects of the present disclosure or portions thereof. The operations described with reference to the example method 1200 may be performed by or in accordance with any of the systems, devices, components, techniques described herein, or combinations thereof, such as the systems, devices, components, techniques described with reference to fig. 1-11 above and fig. 13-17 below.

At operation 1202, the method may include: a core (e.g., cores 510, 610, 710, 810, 906, 1110) is formed. In some aspects, forming the core may include: at least a portion of the core is formed from SiSiC or SiC. In some aspects, forming the core may include: a plurality of burls are formed on the surface of the core. In some aspects, the plurality of burls may be configured to support an object, such as a wafer. For example, a plurality of burls may be formed on a top side of the core and configured to face during operation of the lithographic apparatusToward the wafer. In some aspects, forming the plurality of burls may include: at least a portion of the plurality of burls is formed from DLC, alN, siN or CrN. In some aspects, forming the plurality of burls may include: forming at least one burl of the plurality of burls to have a diameter of less than about 10 ⁷ Nm ^-1 Is a part of the stiffness of the steel sheet. In some aspects, forming the plurality of burls may include: forming a first burl in a central region of the core; forming a second burl in a peripheral region of the core; forming a first groove surrounding the first burl; and forming a second groove surrounding the second burl, wherein the second burl has a length greater than a length of the first burl, wherein a depth of the first groove is less than a depth of the second groove, and wherein a stiffness of the second burl is less than a stiffness of the first burl. In some aspects, forming the core may include: a groove is formed around at least one of the plurality of burls. In some aspects, forming the core may include: a core is formed having a stiffness greater than the stiffness of the vacuum panel and optionally greater than the stiffness of the electrostatic panel. In some aspects, the core may be configured to be connected to the vacuum plate and the electrostatic plate such that the plurality of burls of the core are aligned with the plurality of recesses of the vacuum plate and the plurality of apertures of the electrostatic plate. In some aspects, forming the core may be accomplished using suitable mechanical methods or other methods, and include: the core is formed according to any one or combination of aspects described above with reference to fig. 1-11 and below with reference to fig. 13-17.

At operation 1204, the method may include: vacuum sheets (e.g., vacuum sheets 520, 620, 720; a combined structure of metal layer 820, compliant layer 840, and substrate 851) are formed. In some aspects, forming the vacuum sheet may include: at least a portion of the vacuum panel is formed from fused silica. In some aspects, forming the vacuum sheet may include: a plurality of vacuum connection portions are formed in the vacuum sheet. In some aspects, forming the vacuum sheet may include: a plurality of recesses are formed in a surface of the vacuum sheet, the plurality of recesses configured to receive the plurality of burls of the core. In some aspects, forming the vacuum sheet may include: an electrode layer including one or more electrodes is formed on a surface of the vacuum sheet. In some aspects, forming the electrode layer of the vacuum sheet may include: at least a part of the electrode layer of the vacuum sheet is formed of Cu or CrN. In some aspects, forming the vacuum sheet may include: a vacuum sheet is formed having a stiffness less than the stiffness of the core and optionally greater than the stiffness of the electrostatic sheet. In some aspects, the vacuum plate may be configured to connect the core to the electrostatic plate such that the plurality of recesses of the vacuum plate are aligned with the plurality of burls of the core and the plurality of apertures of the electrostatic plate. In some aspects, the vacuum sheet may be configured to: the electrostatic sheet is vacuum clamped to the vacuum sheet in response to applying vacuum to the plurality of vacuum connections of the vacuum sheet. In some aspects, where the vacuum sheet includes an electrode layer, the vacuum sheet may be configured to: the electrostatic sheet is electrostatically clamped to the vacuum sheet in response to applying a voltage to the electrode layer of the vacuum sheet. In some aspects, forming the vacuum panel may be accomplished using suitable mechanical or other methods, and includes: the vacuum sheet is formed according to any one or a combination of aspects described above with reference to fig. 1 to 11 and below with reference to fig. 13 to 17.

At operation 1206, the method may include: electrostatic sheets (e.g., electrostatic sheets 530, 630, 730, 830) are formed. In some aspects, forming the electrostatic sheet may include: at least a first portion of the electrostatic sheet is formed from a conductive material (e.g., one or more electrodes) and at least a second portion of the electrostatic sheet is formed from a dielectric material. For example, forming the electrostatic sheet may include: an electrostatic sheet is formed comprising one or more electrodes sandwiched between two or more dielectric layers. In some aspects, forming the electrostatic sheet may include: a plurality of apertures are formed in the electrostatic sheet, the plurality of apertures configured to receive the plurality of burls of the core. In some aspects, forming the electrostatic sheet may include: an electrostatic sheet is formed that is less rigid than the core and less rigid than the vacuum sheet. In some aspects, the electrostatic sheet may be configured to be connected to the core using a vacuum sheet such that a plurality of apertures of the electrostatic sheet are aligned with a plurality of burls of the core and a plurality of recesses of the vacuum sheet. In some aspects, forming the electrostatic sheet may be accomplished using suitable mechanical or other methods, and includes: the electrostatic patch is formed according to any one or combination of aspects described above with reference to fig. 1-11 and below with reference to fig. 13-17.

At operation 1208, the method may include: the electrostatic sheet is mounted to a vacuum sheet. In some aspects, mounting the electrostatic sheet to the vacuum sheet may include: vacuum is applied to the plurality of vacuum connections of the vacuum plate to vacuum clamp the electrostatic plate to the vacuum plate. In some aspects, where the vacuum plate includes an electrode layer, mounting the electrostatic plate to the vacuum plate may include: a voltage is applied to the electrode layer of the vacuum plate to electrostatically clamp the electrostatic plate to the vacuum plate. In some aspects, mounting the electrostatic sheet to the vacuum sheet may be accomplished using suitable mechanical methods or other methods, and include: the electrostatic sheet is mounted to the vacuum sheet according to any one or combination of aspects described above with reference to fig. 1-11 and below with reference to fig. 13-17.

At operation 1210, the method may include: the electrostatic sheet is mounted to the core using a vacuum sheet. In some aspects, mounting the electrostatic sheet to the core may include: vacuum is applied to the plurality of vacuum connections of the vacuum plate to vacuum clamp the core to the electrostatic plate. In some aspects, where the vacuum sheet includes an electrode layer, mounting the electrostatic sheet to the core may include: a voltage is applied to the electrode layer of the vacuum plate to electrostatically clamp the core to the electrostatic plate. In some aspects, mounting the electrostatic sheet to the core may include: an adhesive material is applied to one or more portions of the core, the electrostatic sheet, or a combination thereof to attach the core to the electrostatic sheet. In some aspects, mounting the electrostatic sheet to the core may be accomplished using suitable mechanical or other methods, and includes: the vacuum sheet is used to mount the electrostatic sheet to the core according to any one or a combination of aspects described above with reference to fig. 1-11 and below with reference to fig. 13-17.

Example vacuum Assembly

Systems, apparatus, and methods are provided for manufacturing a substrate table using a vacuum assembly that includes a vacuum plate, a compliant layer having burls, and a manifold. An example method may include: a compliant layer is formed having a burl configured to support a vacuum plate, a first vacuum connection, and a first atmospheric pressure connection. Alternatively, each nub may be partially or fully surrounded by a groove. The example method may further include: a manifold is formed having a second vacuum connection configured to align with the first vacuum connection and a second atmospheric connection configured to align with the first atmospheric connection. The example method may further include: a compliant layer is mounted to the manifold and a vacuum sheet is mounted to the compliant layer. Optionally, the example method may further include: a vacuum assembly is used to mount the core of the substrate table to the electrostatic sheet.

As described herein, the present disclosure describes various aspects of systems, apparatus, and methods for manufacturing and using a substrate table having a core and an elastomer sheet for an EUV radiation system. In some aspects, the elastomeric sheet may be mounted to the core using a vacuum assembly comprising a vacuum sheet, a compliant layer, and a manifold, wherein the compliant layer comprises nubs for supporting the vacuum sheet.

In some aspects, the present disclosure describes a system. The system may include a vacuum assembly including a compliant layer. The compliant layer may include a plurality of nubs configured to support the vacuum sheet. The compliant layer may also include a plurality of vacuum connections.

In some aspects, at least a portion of the plurality of nubs may be formed from an elastomeric material. In some aspects, at least one burl of the plurality of burls may have a stiffness of less than about 10 meganewtons per meter (10 ⁷ Nm ^-1 ). In some aspects, the plurality of burls may include a first burl having a first taper angle toward a top of the first burl and a second taper angle toward a bottom of the first burl.

In some aspects, the plurality of burls can include a first burl subset disposed in a first region of the compliant layer and a second burl subset disposed in a second region of the compliant layer, and a first burl pitch of the plurality of first burls can be less than a second burl pitch of the second burl subset. In some aspects, the plurality of burls may be a plurality of first burls, and the first pattern of the plurality of first burls may correspond to a second pattern of a plurality of second burls disposed on a core configured to be attached to a vacuum sheet.

In some aspects, the plurality of vacuum connections may be a plurality of first vacuum connections, and the vacuum assembly may further include a manifold including a plurality of second vacuum connections configured to align with the plurality of first vacuum connections. In some aspects, the compliant layer may further include a first atmospheric pressure connection, and the manifold may further include a second atmospheric pressure connection configured to align with the first atmospheric pressure connection.

In some aspects, the compliant layer may further include a plurality of grooves, and each of the plurality of burls may be surrounded by a respective groove of the plurality of grooves. In some aspects, the plurality of burls may include: a first burl disposed in a first region of the compliant layer, and a second burl disposed in a second region of the compliant layer, and the first length of the first burl may be less than the second length of the second burl. In some aspects, the plurality of grooves may include a first groove surrounding the first burl and a second groove surrounding the second burl, and the first depth of the first groove may be less than the second depth of the second groove. In some aspects, the first stiffness of the first burl may be less than the second stiffness of the second burl.

In some aspects, the disclosure describes an apparatus, such as a vacuum assembly. The apparatus may include a compliant layer including a plurality of nubs configured to support a vacuum plate, a plurality of first vacuum connections, and a first atmospheric pressure connection. The apparatus may also include a manifold configured to be mounted to the compliant layer and including a plurality of second vacuum connections configured to align with the plurality of first vacuum connections, and a second atmospheric pressure connection configured to align with the first atmospheric pressure connection. In some aspects, the device may further comprise a vacuum panel.

In some aspects, at least a portion of the plurality of nubs may be formed from an elastomeric material. In some aspects, the plurality of burls may include a first burl subset disposed in a first region of the compliant layer and a second burl subset disposed in a second region of the compliant layer, and the first burl spacing of the plurality of first burls may be less than the second burl spacing of the second burl subset. In some aspects, the plurality of burls may be a plurality of first burls, and the first pattern of the plurality of first burls may correspond to a second pattern of a plurality of second burls disposed on a core configured to contact the vacuum panel.

In some aspects, the plurality of burls may include a first burl having a first taper angle toward a top of the first burl and a second taper angle toward a bottom of the first burl. In some aspects, the compliant layer may further include a plurality of grooves, and each of the plurality of burls may be surrounded by a respective groove of the plurality of grooves.

In some aspects, a method of manufacturing a vacuum assembly is described. The method may include: a compliant layer is formed that includes a plurality of burls configured to support a vacuum sheet, a plurality of first vacuum connections, and a first atmospheric pressure connection. In some aspects, at least one nub may be surrounded by a groove. The method may further comprise: a manifold is formed that includes a plurality of second vacuum connections configured to align with the plurality of first vacuum connections, and a second atmospheric pressure connection configured to align with the first atmospheric pressure connection. The method may further comprise: the compliant layer is mounted to the manifold. In some aspects, the method may further comprise: a vacuum patch is mounted to the compliant layer.

In some aspects, loading the vacuum sheet to the compliant layer may be a dynamic process when manufacturing the example substrate table, where the interaction between the vacuum sheet and the burls of the compliant layer is complex, as well as time-dependent gas pressure between the vacuum sheet and the compliant layer due to locally varying distances (e.g., volume changes) between the vacuum sheet and the compliant layer. Aspects of the present disclosure provide for optimizing the behavior of vacuum pressure transients during substrate table fabrication (e.g., when the distance between the vacuum plate and compliant layer is locally changing) by: the distance between the burls top and the lowered planar height (e.g., the surface on which the burls are disposed) is decoupled or partially decoupled from the total volume between the vacuum sheet and the compliant layer without altering the overall above-surface geometry of the flexible burls (e.g., the height of the burls top, the pattern, and the contact area). By increasing the volume under the surface of the compliant layer, the time to build the vacuum increases, creating a slower ramp of clamping force and less lateral loading (e.g., bending) in the vacuum sheet. Without the flexible burls, increasing the volume may increase the distance between the burls top and the lowered planar height, making it more difficult to grip the warped vacuum panel (e.g., making the initial distance to begin forming the vacuum larger). Due to the techniques described in this disclosure, the compliant layer may become more compliant, for example, by decoupling the volume from the distance between the burls top and the reduced planar height using flexible burls, such that forces applied during manufacturing may cause the vacuum sheet to more fully conform to the substrate table while reducing lateral loading in the vacuum sheet.

In some aspects, the compliant layer of the vacuum assembly may have patterned structures (e.g., burl patterns) that provide fine tuning of stiffness in different functional areas of the core. In some aspects, the compliant layer burl pattern can be tuned to minimize lateral loading (e.g., bending) in the vacuum panel. In some aspects, the compliant layer burl pattern can be formed by laser ablation. In some aspects, the compliant layer may serve as a vacuum feedthrough between the manifold and the vacuum plate. In some aspects, the internode space may be open to the atmosphere.

In some aspects, burls on the top surface of the elastomeric compliant layer may be manufactured using a subtractive manufacturing process such as laser ablation.

In one example, creating a three-dimensional (3D) structure (such as burls on a surface of a compliant layer of a vacuum assembly) with an elastomeric material may include: the material is injection molded or compression molded into a cavity having the desired geometry. However, machining errors in the mold result in errors in the final part geometry. For example, a part with a flat bottom and a burl structure on top requires a mold with a flat bottom hole drilled via a Computer Numerical Control (CNC) machine. The contour tolerance of the bottom surface of the hole defining the burl top plane is determined by how the CNC machine can reproducibly drill into a particular location in the Z-axis. Further, molding techniques are sensitive to the ability of the material to flow into the features of the mold and therefore can only be used to make a limited number of geometries.

In another example, creating a 3D structure with an elastomeric material may include: 3D prints certain types of rubber. However, 3D printing has very limited material choices, which greatly limit the design freedom of the rubber part.

In yet another example, creating a 3D structure with an elastomeric material may include grinding, which requires that the material have a very strong hardness and be submerged by liquid nitrogen during processing. However, the rubber material used for some example compliant layers may be too soft to be ground.

In contrast, the present disclosure discloses techniques for optimizing the flatness and parallelism of elastomeric materials through subtractive manufacturing processes such as laser ablation. Such subtractive manufacturing techniques may optimize the manufacturing process for blanks of elastomeric material while enabling the reverse removal of material to form sharp, complex features with high precision. Further, such subtractive manufacturing techniques may utilize materials other than that which may flow through an injection mold or be ground, and the materials are not limited to just the geometries that may be manufactured via compression or injection molding or grinding. Still further, such subtractive manufacturing techniques may cut compliant layers from sheets of elastomeric material that have been manufactured in a manner that optimizes flatness and parallelism.

The systems, apparatuses, methods, and computer program products disclosed herein have many exemplary aspects. For example, aspects of the present disclosure provide subtractive manufacturing techniques, such as laser ablation techniques, for manufacturing compliant layers that do not require a mold and thus do not impose a parasitic tooling cost or mold manufacturing lead time when manufacturing the component. Because of the techniques described in this disclosure, the design iterative feedback loop is greatly shortened and becomes cheaper.

Fig. 13A and 13B are cross-sectional illustrations of portions of an example EUV substrate table manufacturing system 1300 according to some aspects of the present disclosure. It should be appreciated that the example EUV substrate table manufacturing system 1300 may be used in applications other than EUV.

As shown in fig. 13A, in some aspects, an example EUV substrate table fabrication system 1300 may include an example EUV substrate table 1301, the example EUV substrate table 1301 including a core 1310 and an electrostatic sheet 1330. In some aspects, the example EUV substrate table manufacturing system 1300 may also include a vacuum assembly 1302, the vacuum assembly 1302 including a vacuum plate 1320, a compliant layer 1340, and a manifold 1351.

In some aspects, the core 1310 may be mounted to the electrostatic sheet 1330 using the vacuum assembly 1302. In some aspects, an example EUV substrate table 1301 may be placed on the vacuum assembly 1302, and a weight 1380 (e.g., a steel plate placed on the core 1310; or in some aspects, electromechanical) may be placed on the example EUV substrate table 1301 to maintain the core 1310 pressed into the compliant layer 1340 while applying a vacuum clamping force to the vacuum sheet 1320 via the vacuum connection 1323. In some aspects, once the manufacturing process is complete, the weight 1380 may be removed from the example EUV substrate table 1301 and the example EUV substrate table 1301 may be removed from the vacuum assembly 1302.

In some aspects, the core 1310 may include a burl 1312 (e.g., a glass burl, a rigid burl, a flexible burl, or any other suitable burl) configured to connect with a vacuum tab 1320. In some aspects, the burls 1312 can be configured to support an object such as a wafer (e.g., the burls 1312 can be disposed on a top side of the core 1310 and configured to face the wafer during operation of the lithographic apparatus). In some aspects, the core 1310 may also include a burl 1313 (e.g., a glass burl, a hard burl, a flexible burl, or any other suitable burl) configured to support a substrate (e.g., a weighted substrate). In some aspects, the vacuum plate 1320, compliant layer 1340, and manifold 1351 can include a vacuum connection 1323. In some aspects, compliant layer 1340 and manifold 1351 can include one or more atmospheric pressure connections 1371, which one or more atmospheric pressure connections 1371 are configured to vent the internode space between nodes 1372 to the atmosphere. In some aspects, the vacuum tab 1320 may also include a recess configured to receive the burls 1312 (e.g., formed by etching the annular ring 1321 to a depth of between about 14.00 microns +/-0.25 microns and about 20.00 microns +/-0.25 microns at each burl location). In some aspects, the recess depth of the recess may be between about 14.00 microns +/-0.25 microns and about 20.00 microns +/-0.25 microns. In some aspects, the electrostatic plate 1330 may include a plurality of apertures configured to receive the burls 1312. In some aspects, the electrostatic plate 1330 may be configured to be connected to the vacuum plate 1320 such that the aperture of the electrostatic plate 1330 is aligned with the recess of the vacuum plate 1320.

In some aspects, at least a portion of core 1310 may be formed of SiSiC or SiC. In some aspects, at least a portion of the burls 1312 can be formed of SiSiC, siC, DLC, alN, siN or CrN. In some aspects, at least a portion of the nubs 1313 can be formed of SiSiC, siC, DLC, alN, siN or CrN. In some aspects, at least a portion of the vacuum sheet 1320 may be formed of fused silica. In some aspects, at least a portion of the electrostatic sheet 1330 may be formed from borosilicate glass. In some aspects, at least another portion of the electrostatic sheet 1330 may be formed of a conductive material. In some aspects, the electrostatic sheet 1330 can include one or more electrodes sandwiched between two or more dielectric layers (such as two glass wafers). In some aspects, compliant layer 1340 may be or include a flexible support structure formed from an elastomeric material such as: silicone (e.g., a 20A durometer silicone or another soft, low durometer polymer), PDMS (e.g., formed using a 25:1 elastomer matrix to elastomer curative mixing ratio), a fluoroelastomer material (e.g., a fluorinated hydrocarbon rubber), any other suitable material, or any combination thereof.

In some aspects, the vacuum tab 1320 may include an upper portion of the vacuum connection 1323. In some aspects, the compliant layer 1340 can include nubs 1372 configured to support the vacuum plate 1320, intermediate portions of the vacuum connections 1323, and upper portions of the one or more atmospheric pressure connections 1371. In some aspects, the manifold 1351 can include a lower portion of the vacuum connection 1323 and a lower portion of one or more atmospheric pressure connections 1371. In some aspects, the middle portion of the vacuum connection 1323 included in the compliant layer 1340 can be aligned (e.g., aligned) with the upper and lower portions of the vacuum connection 1323 included in the vacuum sheet 1320 and manifold 1351, respectively. In some aspects, an upper portion of one or more atmospheric pressure connections 1371 included in compliant layer 1340 may be aligned with a lower portion of one or more atmospheric pressure connections 1371 included in manifold 1351.

In some aspects, the stiffness of the core 1310 may be greater than the stiffness of the vacuum sheet 1320, and the stiffness of the vacuum sheet 1320 may be greater than the stiffness of the electrostatic sheet 1330 and the stiffness of the compliant layer 1340. For example, the compliant layer 1340, the electrostatic sheet 1330, and the vacuum sheet 1320 may have flexibility sufficient to conform to the non-flatness of the core 1310. In some aspects, the pattern of nubs 1372 of the compliant layer 1340 can be tuned to minimize lateral loading (e.g., bending) in the vacuum sheet 1320.

In some aspects, compliant layer 1340, manifold 1351, and stage 1350 can include one or more apertures (e.g., holes) for viewing by an alignment system (e.g., visual alignment system 1360a, visual alignment system 1360 b) to view (e.g., image, capture) alignment marks 1325a disposed on core 1310 and alignment marks 1325b disposed on electrostatic patch 1330.

In some aspects, the recesses of the vacuum plate 1320 may be formed by patterning and etching the vacuum plate 1320 based on the pattern (e.g., number, pitch, location, etc.) of the burls 1312, the pattern of the apertures of the electrostatic plate 1330, or both. Additionally or alternatively, in some aspects, the recesses of the vacuum plate 1320 may be formed by depositing a metal layer (e.g., cu, crN) on the vacuum plate 1320 and then patterning and etching the deposited metal layer based on the pattern of the burls 1312, the pattern of the apertures of the electrostatic plate 1330, or both.

In some aspects, the aperture of the electrostatic plate 1330 may be formed by patterning and etching the electrostatic plate 1330 based on the pattern of burls 1312, the pattern of recesses of the vacuum plate 1320, or both. In some aspects, the aperture of the electrostatic sheet 1330 may be formed by drilling the electrostatic sheet 1330 based on the pattern of the burls 1312, the pattern of the recesses of the vacuum sheet 1320, or both.

In some aspects, the electrostatic sheet 1330 may be configured to be bonded to the core 1310 using an adhesive structure 1334 (e.g., a glue spot applied to the electrostatic sheet 1330).

In some aspects, the vacuum plate 1320 may be configured to: in response to applying vacuum to the vacuum plate 1320, compliant layer 1340, and vacuum connection 1323 of manifold 1351, the electrostatic plate 1330, core 1310, or both are vacuum clamped to the vacuum plate 1320. Additionally or alternatively, in some aspects, the vacuum sheet 1320 may include an electrode layer (e.g., cu or CrN), and the vacuum sheet 1320 may be configured to: in response to applying a voltage to the electrode layer of the vacuum plate 1320, the electrostatic plate 1330, the core 1310, or both are electrostatically clamped to the vacuum plate 1320. In some aspects, the electrostatic sheet 1330 and the vacuum sheet 1320 may be connected to the core 1310 such that the vacuum sheet 1320 and the electrostatic sheet 1330 conform to the non-flatness of the core 1310.

In some aspects, the vacuum plate 1320 may be connected to the electrostatic plate 1330 and the core 1310 such that the aperture of the electrostatic plate 1330 and the burls 1312 of the core 1310 are aligned with the recesses of the vacuum plate 1320. In some aspects, the vacuum plate 1320, the electrostatic plate 1330, or both, may include an electrical pin aperture configured to receive an electrical pin 1370. In some aspects, a vacuum plate 1320 may also be connected to the electrostatic plate 1330 and the core 1310 such that a subset of the electronic pin holes are aligned with the electronic pins 1370.

Fig. 13B illustrates some exemplary features of the compliant layer 1340. As shown in fig. 13B, the compliant layer 1340 may include burls 1372, the burls 1372 being formed on the compliant layer 1340. In some aspects, the processThe nubs 1372 may be configured to support the vacuum plate 1320. For example, nubs 1372 may be formed on the top side of compliant layer 1340 and configured to face the bottom side of the vacuum sheet. In some aspects, nubs 1372 may be formed from an elastomeric material such as: silicone, PDMS, a fluoroelastomer material, any other suitable material, or any combination thereof. In some aspects, burls 1372 may be formed by laser ablation (or using another suitable subtractive manufacturing process) of the top surface of compliant layer 1340. In some aspects, the nub 1372 may have a stiffness of less than about 10 ⁷ Nm ^-1 . In some aspects, nubs 1372 can be formed according to a pattern corresponding to nubs 1312 disposed on core 1310.

In some aspects, the first subset 1372a of nubs 1372 may have a first inter-nub spacing in the central region VI of the compliant layer 1340, the second subset 1372b of nubs 1372 may have a second inter-nub spacing in the near-middle region VII of the compliant layer 1340, the third subset 1372c of nubs 1372 may have a third inter-nub spacing in the far-middle region VIII of the compliant layer 1340, and the fourth subset 1372d of nubs 1372 (alternatively, without nubs) may have a fourth inter-nub spacing in the peripheral region IX of the compliant layer 1340, wherein "first inter-nub spacing < second inter-nub spacing < third inter-nub spacing < fourth inter-nub spacing" is denser near the center of the compliant layer 1340 and sparser near the periphery of the compliant layer 1340. Alternatively, in some aspects, the compliant layer 1340 may have very few or no burls in the peripheral region 1X.

In some aspects, one or more of the nubs 1372 may be flexible nubs, tapered nubs, or both, as described herein. In some aspects, the internode space between the nubs 1372 may be vented to atmosphere through one or more atmospheric pressure connections 1371.

Fig. 14 is a cross-sectional illustration of a portion of another example EUV substrate table fabrication system 1400 in accordance with some aspects of the present disclosure. It should be appreciated that the example EUV substrate table manufacturing system 1400 may be used in applications other than EUV.

In some aspects, the example EUV substrate stage manufacturing system 1400 may include an example EUV substrate stage 1401, the example EUV substrate stage 1401 including a core 1410 and an electrostatic sheet 1430. In some aspects, the example EUV substrate table manufacturing system 1400 may further include a vacuum assembly 1402, the vacuum assembly 1402 including a metal layer 1420, the metal layer 1420 formed on a compliant layer 1440, the compliant layer 1440 mounted on a manifold 1451.

In some aspects, the core 1410 may be mounted to the electrostatic sheet 1430 using the vacuum assembly 1402. In some aspects, an example EUV substrate stage 1401 may be placed on the vacuum assembly 1402, and a weight 1480 (e.g., a steel plate placed on the core 1410; or in some aspects, electromechanical) may be placed on the example EUV substrate stage 1401 to maintain the core 1410 pressed into the compliant layer 1440 while applying a vacuum clamping force to the metal layer 1420 via the vacuum connection 1423. In some aspects, the force applied by the weight 1480 may be adjusted to modify the height of the metal layer 1420. In some aspects, once the manufacturing process is complete, the weight 1480 may be removed from the example EUV substrate stage 1401 and the example EUV substrate stage 1401 may be removed from the vacuum assembly 1402.

In some aspects, the core 1410 may include a burl 1412 (e.g., a glass burl, a rigid burl, a flexible burl, or any other suitable burl) configured to connect with the compliant layer 1440. In some aspects, the burls 1412 may be configured to support an object, such as a wafer (e.g., the burls 1412 may be disposed on a top side of the core 1410 and configured to face the wafer during operation of the lithographic apparatus). In some aspects, the core 1410 may further include a burl 1413 (e.g., a glass burl, a hard burl, a flexible burl, or any other suitable burl), the burl 1413 configured to support a substrate (e.g., a weighted substrate).

In some aspects, the manifold 1451 may include a lower portion of a vacuum connection 1423 (e.g., formed by patterning and etching or any other suitable technique or combination of techniques). In some aspects, the compliant layer 1440 can include an upper portion of the vacuum connection 1423 (e.g., formed by patterning and etching or any other suitable technique or combination of techniques) that is configured to align with a lower portion of the vacuum connection 1423 of the manifold 1451.

In some aspects, the metal layer 1420 may include apertures (e.g., formed by patterning the metal layer 1420 to form annular metal rings, wherein each annular metal ring surrounds a respective burl and has a height of between about 14.00 microns +/-0.25 microns and about 20.00 microns +/-0.25 microns) configured to receive the burls 1412. In some aspects, the apertures of the metal layer 1420 may be formed by depositing a metal layer (e.g., cu, crN) on the compliant layer 1440 and then patterning and etching the deposited metal layer based on the pattern of the burls 1412 (e.g., number, pitch, location, etc.), the pattern of apertures of the electrostatic sheets 1430, or both.

In some aspects, the electrostatic sheet 1430 may include an aperture configured to receive the burls 1412. In some aspects, the electrostatic sheet 1430 may be configured to be connected to the metal layer 1420 such that the aperture of the electrostatic sheet 1430 is aligned with the aperture of the metal layer 1420. In some aspects, the apertures of the electrostatic sheet 1430 may be formed by patterning and etching the electrostatic sheet 1430 based on the pattern of the burls 1412, the pattern of the apertures of the metal layer 1420, or both. In some aspects, the apertures of the electrostatic sheet 1430 may be formed by drilling the electrostatic sheet 1430 based on the pattern of burls 1412, the pattern of apertures of the metal layer 1420, or both.

In some aspects, at least a portion of the core 1410 may be formed of SiSiC. In some aspects, at least a portion of the burls 1412 may be formed from DLC, alN, siN or CrN. In some aspects, at least a portion of the nubs 1413 can be formed of DLC, alN, siN or CrN. In some aspects, at least a portion of the metal layer 1420 may be formed of Cu or CrN. In some aspects, at least a portion of the electrostatic sheet 1430 may be formed from borosilicate glass. In some aspects, at least another portion of the electrostatic sheet 1430 may be formed of a conductive material. In some aspects, the electrostatic sheet 1430 may include one or more electrodes sandwiched between two or more dielectric layers (such as two glass wafers). In some aspects, compliant layer 1440 can be or include a flexible support structure formed from an elastomeric material such as: silicone, PDMS, a fluoroelastomer material, any other suitable material, or any combination thereof. In some aspects, at least a portion of the manifold 1451 may be formed of fused silica. In some aspects, the manifold 1451 may be any suitable substrate, such as a glass wafer.

In some aspects, the stiffness of the core 1410 may be greater than the stiffness of the electrostatic sheet 1430. In some aspects, the stiffness of the core 1410 may be greater than the stiffness of the compliant layer 1440. For example, the electrostatic sheet 1430, the compliant layer 1440, or both may have sufficient flexibility to conform to the non-flatness of the core 1410. In some aspects, the electrostatic sheet 1430 may be configured to be bonded to the core 1410 using an adhesive structure 1434 (e.g., a glue spot applied to the electrostatic sheet 1430).

In some aspects, the manifold 1451 may be configured to: in response to applying vacuum to the vacuum connection 1423 of the manifold 1451, the electrostatic sheet 1430, the core 1410, or both are vacuum clamped to the metal layer 1420, the compliant layer 1440, and the manifold 1451. Additionally or alternatively, in some aspects, the metal layer 1420 may be configured to: in response to applying a voltage to the metal layer 1420, the electrostatic sheet 1430, the core 1410, or both are electrostatically clamped to the metal layer 1420, the compliant layer 1440, and the manifold 1451. In some aspects, the electrostatic sheet 1430, the metal layer 1420, the compliant layer 1440, and the manifold 1451 may be connected to the core 1410 such that the compliant layer 1440 and the electrostatic sheet 1430 conform to the non-planarity of the core 1410.

In some aspects, the metal layer 1420 and compliant layer 1440 may be connected to the electrostatic sheet 1430 and the core 1410 such that the aperture of the electrostatic sheet 1430 and the burls 1412 of the core 1410 are aligned with the aperture of the metal layer 1420. In some aspects, the electrostatic sheet 1430, compliant layer 1440, manifold 1451, or a combination thereof, may include electronic pin holes configured to receive the electronic pins 1470. In some aspects, the metal layer 1420 and compliant layer 1440 may also be connected to the electrostatic sheet 1430 and the core 1410 such that a subset of the electronic pin holes are aligned with the electronic pins 1470.

Fig. 15A, 15B, and 15C are cross-sectional illustrations of an example burls (referred to herein as "flexible burls") surrounded by example grooves, according to some aspects of the invention. In some aspects, the example flexible burls shown in fig. 15A, 15B, and 15C may be incorporated into any of the example substrate tables disclosed herein, such as on a top surface of the example compliant layer.

As shown in fig. 15A, in some aspects, an example flexible burls 1500 can include burls 1502, the burls 1502 surrounded by grooves 1504 formed in a compliant layer 1506. In some aspects, the grooves 1504 may be formed around the burls 1502 using, for example, deep Reactive Ion Etching (DRIE), laser ablation, powder blasting, chemical etching, or another suitable technique. In some aspects, trenches 1504 may be etched directly into compliant layer 1506, into one or more layers disposed on compliant layer 1506, or a combination thereof. In some aspects, one or more portions of the burls 1502 may be formed from an elastomeric material such as: silicone (e.g., a 20A durometer silicone or another soft, low durometer polymer), PDMS (e.g., formed using a 25:1 elastomer matrix to elastomer curative mixing ratio), a fluoroelastomer material (e.g., a fluorinated hydrocarbon rubber), any other suitable material, or any combination thereof. In some aspects, the top diameter of the burls 1502 may be about 100 microns to about 500 microns. For example, the top diameter of the burls 1502 may be about 210 microns. In some aspects, the burls 1502 may have a stiffness of less than about 10 ⁷ Nm ^-1 。

As shown in fig. 15B, in some aspects, an example flexible burls 1520 can include burls 1522, the burls 1522 being surrounded by grooves 1524 formed in the compliant layer 1526. In some aspects, the top of the burls 1522 may be disposed at about a height level a, the non-burl surface of the compliant layer 1526 may be disposed at about a height level B, and the bottom of the trench 1524 may be disposed at about a height of waterAt level C. In some aspects, the burls 1522 may have a profile f (z) as a function of height z that may be optimized for stiffness and robustness while meeting requirements for burl top contact area and volumetric footprint. In some aspects, the profile f (z) can increase the burl width toward the bottom of burl 1522 (e.g., height level C) and decrease the burl width toward the top of burl 1522 (e.g., height level a). In one illustrative and non-limiting example, the burl 1522 may have a first taper angle α toward the top of the burl 1522 ₁ And a second taper angle alpha toward the bottom of the boss 1522 ₂ Wherein the first taper angle alpha ₁ With a second cone angle alpha ₂ Different. In some aspects, one or more portions of the nub 1522 may have a profile f (z) that includes one or more discrete steps (e.g., rather than a continuous taper angle).

In some aspects, the distance a-B of the vacuum sheet to the compliant layer may range from about 10.0 microns to greater than 1.0mm. In some aspects, the length of the nubs 1522 (e.g., the distance a-C) may range from about 10.0 microns to greater than 1.0mm (e.g., from about 100 microns to about 2.5 mm). In some aspects, the depth of the grooves 1544 (e.g., distance B-C) may range from about 50.0 microns to greater than 1.0mm (e.g., from about 100 microns to about 2.5 mm). In one illustrative and non-limiting example, the vacuum pad to compliant layer distance a-B may be about 10 microns, the height of the nubs 1522 (e.g., distance a-C) may be about 100 microns, and the depth of the grooves 1524 (e.g., distance B-C) may be about 150 microns.

As shown in fig. 15C, in some aspects, an example flexible burls 1540 can include burls 1542, the burls 1542 being surrounded by grooves 1544 formed in a compliant layer 1546. In some aspects, the depth, width, shape, or a combination thereof of the grooves 1544 may be tailored to generate a desired lateral burl stiffness and vacuum volume. For example, fig. 15C shows a representative, not-to-scale illustration of the design freedom of the vacuum volume (i.e., white area) between the substrate at level a and the substrate table at level B, without changing the stiffness of the burls 1542. In some aspects Different vacuum sheet-to-compliant layer distances a-B (e.g., from about 10.0 microns to greater than 1.0 microns) can be obtained while maintaining the vacuum volume substantially the same. For example, the distance A-B of the first vacuum sheet to the compliant layer ₁ May provide a distance a-B from the second vacuum sheet to the compliant layer ₂ Substantially the same vacuum volume, with the trenches 1544 at the same level as the height level B ₁ The width when associated is greater than the width of trench 1544 at height level B ₂ Width at time of association.

FIGS. 16A and 16B are plan and cross-sectional illustrations of an example substrate table surface including example burls surrounded by example grooves, according to some aspects of the disclosure. Fig. 16A illustrates a plan view (e.g., top view) of a portion of an exemplary vacuum assembly 1600. FIG. 16B shows a cross-section from the center to the edge (e.g., 0.ltoreq.r.ltoreq.150 mm) of compliant layer 1610 through a portion of an exemplary vacuum assembly 1600.

As shown in fig. 16A and 16B, the example vacuum assembly 1600 may include flexible burls formed in or on a compliant layer 1610 (e.g., a top surface or a bottom surface of a compliant layer such as the compliant layer 1340 described with reference to fig. 13A and 13B). The flexible burls may include, for example, 30000 flexible burls. In some aspects, each flexible burl may be about 175 microns high and have a top diameter of about 210 microns. In some aspects, the pitch between the flexible burls can be about 1.5mm.

In some aspects, the difference in height between the surface of the compliant layer 1610 and the top of each of the burls (e.g., the vacuum sheet-to-compliant layer distance a-B) may be substantially constant across the compliant layer 1610, while the difference in height between the bottom of each of the grooves and the top of each of the burls may vary across the compliant layer 1610. For example, the trench depth B-C may increase as the distance r increases from the center of the compliant layer 1610. Thus, in some aspects, the length and stiffness of each burl can vary across the compliant layer 1610 without altering the height of the burl top above the compliant layer 1610 surface. For example, as the distance r increases from the center of the compliant layer 1610, the burl length a-C may increase and the burl stiffness may decrease. In other words, the burls disposed in the peripheral region of the compliant layer 1610 may have a greater length and a lower stiffness than the burls disposed in the central region of the compliant layer 1610. In some aspects, the burls disposed near the perimeter of the compliant layer 1610 may have a lower stiffness so that they may be displaced with less force to more easily follow the expanding surface of the substrate due to thermal loading.

In some aspects, the flexible burls can include a first flexible burl subset surrounded by a first groove subset, such as burl 1602 surrounded by groove 1604, in the central region XI. In some aspects, the flexible nubs may include a second subset of nubs surrounded by a second subset of grooves, such as nubs 1622 surrounded by grooves 1624, in intermediate region XII. In some aspects, the flexible burls may include a third burl subset surrounded by a third groove subset, such as burl 1642 surrounded by groove 1644, in peripheral region XIII.

In some aspects, the depth of each trench in the first subset of trenches in the central region XI may be less than the depth of each trench in the second subset of trenches in the intermediate region XII. In some aspects, the depth of each trench in the second subset of trenches in intermediate region XII may be less than the depth of each trench in the third subset of trenches in peripheral region XIII. For example, the depth 1605 (e.g., distance B-C) of the trench 1604 in the central region XI ₁ ) Possibly less than the depth 1625 (e.g., distance B-C) of the trench 1624 in the intermediate region XII ₂ ) And the depth 1625 of the trench 1624 in the middle region XII may be less than the depth 1645 of the trench 1644 in the peripheral region XIII (e.g., distance B-C ₃ )。

In some aspects, the length of each burl in the first subset of burls in the central region XI may be greater than the length of each burl in the second subset of burls in the intermediate region XII. In some aspects, the length of each burl in the second subset of burls in intermediate region XII may be greater than the length of each burl in the third subset of burls in peripheral region XIII. For example in the central region XILength 1603 of burls 1602 (e.g., distance a-C ₁ ) May be greater than the length 1623 of the nub 1622 in the intermediate region XII (e.g., distance a-C ₂ ) And the length 1623 of the nub 1622 in the intermediate region XII may be greater than the length 1643 of the nub 1642 in the peripheral region XIII (e.g., distance a-C ₃ )。

In some aspects, the stiffness of each burl in the first subset of burls in the central region XI may be greater than the stiffness of each burl in the second subset of burls in the intermediate region XII. In some aspects, each burl in the second subset of burls in intermediate region XII may have a hardness that is greater than the hardness of each burl in the third subset of burls in peripheral region XIII. For example, the stiffness of the burls 1602 in the central region XI may be greater than the stiffness of the burls 1622 in the intermediate region XII, and the stiffness of the burls 1622 in the intermediate region XII may be greater than the stiffness of the burls 1642 in the peripheral region XIII.

Example procedure for manufacturing an apparatus

Fig. 17 is an example method 1700 of manufacturing a device, or portion thereof, in accordance with some aspects of the present disclosure. The operations described with reference to the example method 1700 may be performed by or in accordance with any of the systems, devices, components, techniques, or combinations thereof described herein, such as the systems, devices, components, techniques, or combinations thereof described above with reference to fig. 1-16.

At operation 1702, the method may include: forming cores (e.g., cores 1310, 1410). In some aspects, forming the core may be accomplished using suitable mechanical methods or other methods, and include: the core is formed according to any one or combination of aspects described above with reference to fig. 1-16.

In some aspects, forming the core may include: at least a portion of the core is formed from SiSiC or SiC. In some aspects, forming the core may include: burls (e.g., burls 1312, 1313, 1412, 1413, 1500, 1502, 1520, 1522, 1540, 1542, 1602, 1622, 1642) are formed on a surface of the core. In some aspects, the burls may be configured to support a substrate such as a wafer An object. For example, burls may be formed on a top side of the core and configured to face the wafer during operation of the lithographic apparatus. In some aspects, forming the burls may include: at least a portion of the burls are formed from DLC, alN, siN or CrN. In some aspects, forming the burls may include: forming a hardness of less than about 10 ⁷ Nm ^-1 Is provided.

In some aspects, forming the core may include: grooves (e.g., grooves 1504, 1524, 1544, 1604, 1624, 1644) are formed around at least one burl. In some aspects, forming the burls may include: forming a first burl in a central region of the core (e.g., central region XI shown in fig. 16A and 16B); forming a second burl in a peripheral region of the core (e.g., intermediate region XIII shown in fig. 16A and 16B); forming a first groove surrounding the first burl; and forming a second groove surrounding the second burl, wherein the second burl has a length greater than a length of the first burl, wherein a depth of the first groove is less than a depth of the second groove, and wherein a stiffness of the second burl is less than a stiffness of the first burl. In some aspects, forming the core may include: a core is formed having a stiffness greater than the stiffness of the vacuum panel and optionally greater than the stiffness of the electrostatic panel. In some aspects, the core may be configured to be connected to the vacuum plate and the electrostatic plate such that the nubs of the core align with the recesses of the vacuum plate and the apertures of the electrostatic plate.

At operation 1704, the method may include: a vacuum assembly (e.g., vacuum assemblies 1302, 1402) is formed that includes a vacuum plate (e.g., vacuum plate 1320; or metal layer 1420), a compliant layer (e.g., compliant layers 1340, 1440, 1506, 1526, 1546, 1610), and a manifold (e.g., manifolds 1351, 1451). In some aspects, forming the vacuum assembly may be accomplished using suitable mechanical methods or other methods, and include: the vacuum assembly is formed according to any one or combination of aspects described above with reference to fig. 1-16.

In some aspects, forming the vacuum sheet of the vacuum assembly may include: at least a portion of the vacuum panel is formed from fused silica. In some aspects, forming the vacuum sheet may include: a vacuum connection is formed in the vacuum sheet. In some aspects, forming the vacuum sheet may include: a recess is formed in a surface of the vacuum plate, the recess configured to receive a burl of the core. In some aspects, forming the vacuum sheet may include: an electrode layer is formed on a surface of the vacuum sheet, the electrode layer including one or more electrodes. In some aspects, forming the electrode layer of the vacuum sheet may include: at least a part of the electrode layer of the vacuum sheet is formed of Cu or CrN. In some aspects, forming the vacuum sheet may include: a vacuum sheet is formed having a stiffness less than the stiffness of the core and optionally greater than the stiffness of the electrostatic sheet. In some aspects, the vacuum plate may be configured to connect the core to the electrostatic plate such that the recess of the vacuum plate is aligned with the nub of the core and the aperture of the electrostatic plate. In some aspects, the vacuum sheet may be configured to: the electrostatic sheet is vacuum clamped to the vacuum sheet in response to applying vacuum to the vacuum connections of the vacuum sheet. In some aspects, where the vacuum sheet includes an electrode layer, the vacuum sheet may be configured to: the electrostatic sheet is electrostatically clamped to the vacuum sheet in response to applying a voltage to the electrode layer of the vacuum sheet.

In some aspects, forming the compliant layer of the vacuum assembly may include: forming a compliant layer formed from an elastomeric material such as: silicone, PDMS, a fluoroelastomer material, any other suitable material, or any combination thereof. In some aspects, forming the compliant layer may include: burls (e.g., burls 1372, 1500, 1502, 1520, 1522, 1540, 1542, 1602, 1622, 1642) are formed on a surface of the compliant layer. In some aspects, the nubs can be configured to support the vacuum plate. For example, the nubs can be formed on the top side of the compliant layer and configured to face the bottom side of the vacuum sheet. In some aspects, forming the burls may include: forming at least a portion of a burl formed of an elastomeric material such as: silicone, PDMS, a fluoroelastomer material, any other suitable material, or any combination thereof. In some aspects, forming the burls may include: by the top of the compliant layerThe portion surface is laser ablated to form at least a portion of the burls. In some aspects, forming the burls may include: forming a hardness of less than about 10 ⁷ Nm ^-1 Is provided. In some aspects, forming the burls may include: the burls are formed according to a pattern corresponding to burls (e.g., burls 1312) provided on the core. In some aspects, forming the burls may include: forming a first subset of burls in a first region of the compliant layer (e.g., central region VI shown in fig. 13B; central region XI shown in fig. 16A and 16B), the first subset of burls having a first inter-burl spacing; a second subset of burls is formed in a second region of the compliant layer (e.g., peripheral region IX shown in fig. 13B; peripheral region XIII shown in fig. 16A and 16B) having a second inter-burl spacing, wherein a first burl spacing of the plurality of first burls is less than a second burl spacing of the second subset of burls (e.g., burls are denser in the central region and sparser in the peripheral region).

In some aspects, forming the compliant layer may include: grooves (e.g., grooves 1504, 1524, 1544, 1604, 1624, 1644) are formed (e.g., by laser ablation) around at least one burl. In some aspects, forming the burls may include: forming at least one burl having a first taper angle toward the top of the burl (e.g., a first taper angle alpha toward the top of burl 1522) ₁ ) And a second taper angle toward the bottom of the burl (e.g., a second taper angle alpha toward the bottom of burl 1522 ₂ ). In some aspects, forming the burls may include: forming a first burl in a central region of the compliant layer (e.g., central region VI shown in fig. 13B; central region XI shown in fig. 16A and 16B); forming a second burl in a peripheral region of the compliant layer (e.g., peripheral region IX shown in FIG. 13B; peripheral region XIII shown in FIGS. 16A and 16B); forming a first groove around the first burl; and forming a second groove around the second burl, wherein the second burl has a length greater than a length of the first burl, wherein a depth of the first groove is less than a depth of the second groove, and wherein a stiffness of the second burl is less than a stiffness of the first burl.

In some aspects, forming the compliant layer may further comprise: a plurality of first vacuum connections (e.g., upper portions of vacuum connections 1323, 1423) are formed (e.g., by laser ablation) through the compliant layer. In some aspects, forming the compliant layer may further comprise: a first atmospheric pressure connection (e.g., an upper portion of one or more atmospheric pressure connections 1371) is formed through the compliant layer (e.g., by laser ablation).

In some aspects, forming a manifold of a vacuum assembly may include: a manifold is formed from any suitable material, such as one or more of the materials disclosed herein. In some aspects, forming the manifold may further comprise: a plurality of second vacuum connections (e.g., lower portions of vacuum connections 1323, 1423) are formed through the manifold (e.g., by laser ablation). In some aspects, forming the manifold may further comprise: a second atmospheric pressure connection (e.g., a lower portion of one or more atmospheric pressure connections 1371) is formed through the manifold (e.g., by laser ablation).

At operation 1706, the method may include: electrostatic patches (e.g., electrostatic patches 1330, 1430) are formed. In some aspects, forming the electrostatic sheet may include: at least a first portion of the electrostatic sheet is formed from a conductive material (e.g., one or more electrodes) and at least a second portion of the electrostatic sheet is formed from a dielectric material. For example, forming the electrostatic sheet may include: an electrostatic sheet is formed that includes one or more electrodes sandwiched between two or more dielectric layers. In some aspects, forming the electrostatic sheet may include: an aperture is formed in the electrostatic sheet, the aperture configured to receive a burl of the core. In some aspects, forming the electrostatic sheet may include: an electrostatic sheet is formed having a stiffness less than the stiffness of the core and less than the stiffness of the vacuum sheet and the stiffness of the compliant layer. In some aspects, the electrostatic sheet may be configured to be connected to the core using a vacuum assembly such that the aperture of the electrostatic sheet is aligned with the burls of the core and the recesses of the vacuum sheet. In some aspects, forming the electrostatic sheet may be accomplished using suitable mechanical methods or other methods, and include: the electrostatic patch is formed according to any one or combination of aspects described above with reference to fig. 1-16.

At operation 1708, the method may include: the electrostatic sheet is mounted to a vacuum sheet of a vacuum assembly. In some aspects, mounting the electrostatic sheet to the vacuum sheet may include: a vacuum is applied to the vacuum connection of the vacuum assembly to vacuum clamp the electrostatic sheet to the vacuum sheet. In some aspects, where the vacuum plate includes an electrode layer, mounting the electrostatic plate to the vacuum plate may include: a voltage is applied to the electrode layer of the vacuum plate to electrostatically clamp the electrostatic plate to the vacuum plate. In some aspects, mounting the electrostatic sheet to the vacuum sheet may be accomplished using suitable mechanical methods or other methods, and include: the electrostatic sheet is mounted to the vacuum sheet according to any one or combination of aspects described above with reference to fig. 1-16.

At operation 1710, the method may include: the electrostatic sheet was mounted to the core using a vacuum assembly. In some aspects, mounting the electrostatic sheet to the core may include: a vacuum is applied to the vacuum connection of the vacuum assembly to vacuum clamp the core to the electrostatic sheet. In some aspects, where the vacuum sheet of the vacuum assembly includes an electrode layer, mounting the electrostatic sheet to the core may include: a voltage is applied to the electrode layer of the vacuum plate to electrostatically clamp the core to the electrostatic plate. In some aspects, mounting the electrostatic sheet to the core may include: an adhesive material is applied to one or more portions of the core, the electrostatic sheet, or a combination thereof to attach the core to the electrostatic sheet. In some aspects, mounting the electrostatic sheet to the core may be accomplished using suitable mechanical or other methods, and includes: a vacuum assembly is used to mount an electrostatic sheet to a core according to any one or combination of aspects described above with reference to fig. 1-16.

These embodiments may also be described using the following clauses.

1. A substrate table, comprising:

a core, comprising:

a plurality of nubs for supporting an object; and

a plurality of the grooves are formed in the substrate,

wherein each burl of the plurality of burls is surrounded by a respective groove of the plurality of grooves.

2. The substrate table of clause 1, wherein at least a portion of the core is formed of siliconized silicon carbide (SiSiC) or silicon carbide (SiC).

3. The substrate table of clause 1, wherein at least a portion of the plurality of burls is formed of diamond-like carbon (DLC), aluminum nitride (AlN), silicon nitride (SiN), or chromium nitride (CrN).

4. The substrate table of clause 1, wherein at least one burl of the plurality of burls has a stiffness of less than about 10 meganewtons per meter (10 ⁷ Nm ^-1 )。

5. The substrate table according to clause 1, wherein

The plurality of burls includes:

a first burl disposed in a first region of the core; and

a second burl disposed in a second region of the core; and

the second burls have a length that is greater than a length of the first burls.

6. The substrate table according to clause 5, wherein

The plurality of grooves includes:

a first groove surrounding the first burl; and

A second groove surrounding the second burl; and

wherein the depth of the first trench is less than the depth of the second trench.

7. A substrate table according to clause 5, wherein

The second burls have a stiffness less than the stiffness of the first burls.

8. The substrate table of clause 1, wherein

The plurality of burls includes a first burl; and

the first burl has:

a first taper angle toward a top of the first burl; and

and a second taper angle towards the bottom of the first burl.

9. The substrate table of clause 1, wherein the core is further configured to be connected to an electrostatic sheet comprising a plurality of apertures configured to receive the plurality of burls of the core such that the plurality of burls of the core are aligned with the plurality of apertures of the electrostatic sheet.

10. An apparatus, comprising:

a vacuum panel, comprising:

a plurality of vacuum connection parts; and

a plurality of recesses configured to receive the plurality of nubs of the core.

11. The apparatus of clause 10, wherein at least a portion of the vacuum sheet is formed of fused silica.

12. The apparatus of clause 10, wherein the stiffness of the vacuum panel is less than the stiffness of the core.

13. The apparatus according to clause 10, wherein the vacuum sheet is configured to:

mounting the core to an electrostatic sheet, the electrostatic sheet comprising a plurality of apertures configured to receive the plurality of nubs of the core,

wherein the plurality of recesses of the vacuum plate are configured to align with the plurality of apertures of the electrostatic plate.

14. The apparatus of clause 13, wherein the vacuum sheet is configured to: the electrostatic sheet is vacuum clamped to the vacuum sheet in response to applying vacuum to the plurality of vacuum connections of the vacuum sheet.

15. The apparatus of clause 13, wherein

The stiffness of the vacuum sheet is less than the stiffness of the core;

the stiffness of the vacuum sheet is greater than the stiffness of the electrostatic sheet.

16. The apparatus of clause 13, wherein

The vacuum sheet includes an electrode layer including one or more electrodes; and

the vacuum sheet is configured to: the electrostatic sheet is electrostatically clamped to the vacuum sheet in response to one or more voltages applied to one or more of the one or more electrodes in the electrode layer of the vacuum sheet.

17. The apparatus of clause 13, wherein the vacuum sheet comprises a coating disposed on at least a portion of a surface of the vacuum sheet facing the electrostatic sheet.

18. A method of manufacturing a device, comprising:

forming a vacuum sheet, the vacuum sheet comprising:

a plurality of vacuum connection parts; and

a plurality of recesses configured to receive a plurality of nubs of the core; and

the core is mounted to an electrostatic plate using the vacuum plate,

wherein the electrostatic sheet comprises a plurality of apertures configured to receive the plurality of burls.

19. The method of clause 18, further comprising:

the core is mounted to the electrostatic sheet using the vacuum sheet such that the plurality of apertures of the electrostatic sheet are aligned with the plurality of recesses and the plurality of cores of the vacuum sheet.

20. The method according to clause 18, wherein

The plurality of burls configured to support an object; and

at least one of the plurality of burls of the core is surrounded by a groove.

21. A system, comprising:

a vacuum assembly comprising a compliant layer, wherein the compliant layer comprises:

a plurality of nubs configured to support a vacuum plate; and

a plurality of vacuum connections.

22. The system of clause 21, wherein at least a portion of the plurality of burls are formed of an elastomeric material.

23. The system of clause 21, wherein the plurality of burls are to Less than about 10 meganewtons per meter (10) ⁷ Nm ^-1 )。

24. The system according to clause 21, wherein

The plurality of burls includes:

a first subset of nubs disposed in a first region of the compliant layer; and

a second subset of nubs disposed in a second region of the compliant layer; and

wherein a first inter-node spacing of the first subset of nodes is less than a second inter-node spacing of the second subset of nodes.

25. The system of clause 21, wherein

The plurality of burls is a plurality of first burls; and

the first pattern of the first plurality of burls corresponds to the second pattern of the second plurality of burls disposed on a core configured to be attached to the vacuum panel.

26. The system of clause 21, wherein

The plurality of vacuum connection parts are a plurality of first vacuum connection parts;

the vacuum assembly further comprises a manifold;

the manifold includes a plurality of second vacuum connections; and

the plurality of second vacuum connections are configured to align with the plurality of first vacuum connections.

27. The system according to clause 26, wherein

The compliant layer further includes a first atmospheric pressure connection;

the manifold further includes a second atmospheric pressure connection; and

The second atmospheric pressure connection is configured to align with the first atmospheric pressure connection.

28. The system of clause 21, wherein

The plurality of burls includes a first burl; and

the first burl has:

a first taper angle toward a top of the first burl; and

and a second taper angle towards the bottom of the first burl.

29. The system of clause 21, wherein

The compliant layer further includes a plurality of trenches; and

each burl of the plurality of burls is surrounded by a respective groove of the plurality of grooves.

30. The system of clause 29, wherein

The plurality of burls includes:

a first burl disposed in a first region of the compliant layer; and

a second burl disposed in a second region of the compliant layer; and

the first length of the first burl is less than the second length of the second burl.

31. The system of clause 30, wherein

The plurality of grooves includes:

a first groove surrounding the first burl; and

a second groove surrounding the second burl; and

the first depth of the first trench is less than the second depth of the second trench.

32. The system of clause 30, wherein

The first stiffness of the first burl is less than the second stiffness of the second burl.

33. An apparatus, comprising:

a compliant layer, comprising:

a plurality of nubs configured to support the vacuum plate,

a plurality of first vacuum connection parts, and

a first atmospheric pressure connection; and

a manifold configured to mount to the compliant layer and comprising:

a plurality of second vacuum connections configured to align with the plurality of first vacuum connections, and

a second atmospheric pressure connection configured to align with the first atmospheric pressure connection.

34. The device of clause 33, wherein at least a portion of the plurality of burls is formed of an elastomeric material.

35. The apparatus of clause 33, wherein

The plurality of burls includes:

a first subset of nubs disposed in a first region of the compliant layer; and

a second subset of nubs disposed in a second region of the compliant layer; and

36. The apparatus of clause 33, wherein

The plurality of burls is a plurality of first burls; and

37. The apparatus of clause 33, wherein

The plurality of burls includes a first burl;

the first burl has:

a first taper angle toward a top of the first burl; and

and a second taper angle towards the bottom of the first burl.

38. The apparatus according to clause 33, wherein

The compliant layer further includes a plurality of trenches; and

39. A method of manufacturing a vacuum assembly, comprising:

forming a compliant layer, the compliant layer comprising:

a plurality of nubs configured to support the vacuum plate,

a plurality of first vacuum connection parts, and

a first atmospheric pressure connection;

forming a manifold, the manifold comprising:

a second atmospheric pressure connection configured to align with the first atmospheric pressure connection; and

the compliant layer is mounted to the manifold.

40. The method of clause 39, wherein at least one burl of the plurality of burls is surrounded by a groove.

Conclusion(s)

Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other possible applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. Those skilled in the art will appreciate that any use of the terms "wafer" or "die" herein may be considered synonymous with the more general terms "substrate" or "target portion", respectively, in the context of such alternative applications. The substrate indicated herein may be processed, for example, in a track unit (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) or a metrology or inspection unit, either before or after exposure. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed, for example, more than once, for example, to produce a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by one or more persons of ordinary skill in the relevant art in light of the teachings herein.

The term "substrate" as used herein describes a material to which a layer of material is added. In some aspects, the substrate itself may be patterned, and the material added on top thereof may also be patterned, or the material may remain unpatterned.

Examples disclosed herein are illustrative of embodiments of the disclosure and are not limiting. Other suitable modifications and adaptations of the various conditions and parameters normally encountered in the art and which may be apparent to one or more persons skilled in the relevant art are within the spirit and scope of the invention.

While specific aspects of the invention have been described above, it will be appreciated that aspects may be practiced otherwise than as described. This description is not intended to limit embodiments of the present disclosure.

It should be appreciated that the detailed description section is not intended to be illustrative of the background, summary and abstract sections. Summary and summary of the inventionone or more, but not all, example embodiments as contemplated by one or more inventors may be set forth, and thus are not intended to limit the present embodiments and the appended claims in any way.

Some aspects of the present disclosure have been described above with the aid of functional building blocks illustrating the implementation of specific functions and relationships thereof. For ease of description, the boundaries of these functional building blocks are defined herein in any fashion. Alternate boundaries may be defined so long as the specified functions and relationships thereof are appropriately performed.

The foregoing description of the specific aspects of the present disclosure will so fully reveal the general nature of these aspects that others can, by applying knowledge of one skilled in the art, readily modify and/or adapt for various applications such specific aspects without undue experimentation, without departing from the general concept of the present disclosure. Accordingly, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed aspects, based on the teaching and guidance presented herein.

The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary aspects or embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. A substrate table, comprising:

a core, comprising:

a plurality of nubs for supporting an object; and

a plurality of the grooves are formed in the substrate,

2. A substrate table according to claim 1, wherein

At least a portion of the core is formed of siliconized silicon carbide (SiSiC) or silicon carbide (SiC);

at least a portion of the plurality of burls is formed of diamond-like carbon (DLC), aluminum nitride (AlN), silicon nitride (SiN), or chromium nitride (CrN); and/or

At least one of the plurality of burls has a stiffness of less than about 10 meganewtons per meter (10 ⁷ Nm ^-1 )。

3. A substrate table according to claim 1, wherein

The plurality of burls includes:

a first burl disposed in a first region of the core; and

a second burl disposed in a second region of the core, wherein a length of the second burl is greater than a length of the first burl, and wherein a stiffness of the second burl is less than a stiffness of the first burl;

the plurality of grooves includes:

a first groove surrounding the first burl; and

and a second groove surrounding the second burl, wherein the depth of the first groove is smaller than the depth of the second groove.

4. A substrate table according to claim 1, wherein

The plurality of burls includes a first burl;

The first burl has:

a first taper angle toward a top of the first burl; and

a second taper angle toward the bottom of the first burl; and/or

The core is also configured to be connected to an electrostatic sheet that includes a plurality of apertures configured to receive the plurality of burls of the core such that the plurality of burls of the core are aligned with the plurality of apertures of the electrostatic sheet.

5. An apparatus, comprising:

a vacuum panel, comprising:

a plurality of vacuum connection parts; and

6. The apparatus of claim 5, wherein at least a portion of the vacuum sheet is formed of fused quartz, and/or wherein the vacuum sheet has a stiffness that is less than a stiffness of the core.

7. The apparatus of claim 5, wherein the vacuum sheet is configured to:

mounting the core to an electrostatic sheet, the electrostatic sheet comprising a plurality of apertures configured to receive the plurality of burls of the core,

8. The apparatus of claim 7, wherein the vacuum sheet is configured to: the electrostatic sheet is vacuum clamped to the vacuum sheet in response to applying vacuum to the plurality of vacuum connections of the vacuum sheet.

9. The apparatus of claim 7, wherein

The stiffness of the vacuum sheet is less than the stiffness of the core;

the stiffness of the vacuum sheet is greater than the stiffness of the electrostatic sheet, and/or

The vacuum plate includes a coating disposed on at least a portion of a surface of the vacuum plate facing the electrostatic plate.

10. The apparatus of claim 7, wherein

11. A system, comprising:

a plurality of nubs configured to support a vacuum plate; and

a plurality of vacuum connections.

12. The system of claim 11, wherein

The plurality of burls includes:

a first subset of nubs disposed in a first region of the compliant layer; and

a second subset of burls disposed in a second region of the compliant layer, wherein a first inter-bump spacing of the first subset of burls is less than a second inter-bump spacing of the second subset of burls.

13. The system of claim 11, wherein

The plurality of burls is a plurality of first burls; and

14. The system of claim 11, wherein

the vacuum assembly further comprises a manifold;

the manifold includes a plurality of second vacuum connections; and

15. The system of claim 14, wherein

The compliant layer further includes a first atmospheric pressure connection;

the manifold further includes a second atmospheric pressure connection; and