Heater assemblies, substrate supports, and lithography equipment

Abstract

The heater assembly is a heater assembly used on a generally cylindrical substrate support, comprising a first heater portion configured to be fixed to the circumferential surface of the substrate support, and a second heater portion configured to be fixed to the circumferential surface of the substrate support, wherein the first end of the first heater portion and the second end of the second heater portion are configured to overlap in the axial direction of the substrate support when fixed to the circumferential surface.

Description

Technical Field

[0001] Cross - reference to related applications

[0001] This application claims the priority of European Patent No. 23177493.6 filed on June 6, 2023, the entire content of which is incorporated herein by reference.

[0002]

[0002] The present invention relates to a heater assembly for a substrate support configured to support a substrate, a substrate support having the heater assembly, a lithographic apparatus including the substrate support, a method of supporting a substrate, and a method of manufacturing a device including the method of supporting a substrate.

Background Art

[0003]

[0003] A lithographic apparatus is a machine configured to apply a desired pattern to a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus can project, for example, using a projection system, a pattern of a patterning device (e.g., a mask) (often referred to as a “design layout” or “design”) onto a layer of radiation - sensitive material (resist) provided on a substrate (e.g., a wafer). Known lithographic apparatuses include so - called steppers, in which each target portion is irradiated by exposing the entire pattern once to the target portion, and so - called scanners, in which each target portion is irradiated by scanning the pattern in a direction with a radiation beam while synchronously scanning the substrate parallel or antiparallel to a given direction (the “scan” direction).

[0004]

[0004] As semiconductor manufacturing processes continue to advance, the dimensions of circuit elements have continuously decreased, while the number of functional elements such as transistors per device has steadily increased over decades, following a trend commonly known as Moore's Law. To keep up with Moore's Law, the semiconductor industry is pursuing technologies that enable the creation of increasingly smaller features. To project patterns onto a substrate, lithography equipment can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the feature that can be patterned on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm.

[0005]

[0005] Further improvement in the resolution of smaller features can be achieved by providing an immersion fluid with a relatively high refractive index, such as water, on the substrate during exposure. Since exposure radiation has shorter wavelengths in a fluid than in a gas, the effect of the immersion fluid is that it enables imaging of smaller features. The effect of the immersion fluid can also be thought of as increasing the effective numerical aperture (NA) and depth of field of the system.

[0006]

[0006] The immersion fluid can be confined to a local area between the projection system of the lithography apparatus and the substrate by the fluid handling structure.

[0007]

[0007] In a lithography apparatus, it is desirable to control the temperature of one or more parts of the lithography apparatus. For example, it is desirable to keep the temperature of a part substantially constant even when a thermal load (e.g., heating and / or cooling) is applied to that part. Such thermal loads may be due to the supply and / or removal of fluid in an immersion lithography apparatus. For example, gas removal may cause undesirable evaporation of the liquid adjacent to the gas removal. This may result in localized cooling. Localized cooling is undesirable because it can cause thermal contraction of adjacent parts and lead to errors. Localized cooling may occur, for example, in the interior or adjacent parts of a fluid confinement structure, substrate support, etc.

[0008]

[0008] Therefore, it has been proposed to provide a heater assembly fixed to the periphery of the substrate support in order to compensate for the heat load (e.g., cooling) caused by the evaporation of the immersion fluid extracted through the extraction channel adjacent to the edge of the substrate support. [Overview of the project]

[0009]

[0009] Further improvements are desired in the configuration for controlling the temperature of the substrate support. For example, it is desirable to provide an improved heater assembly, a substrate support having such a heater assembly, a lithography apparatus having such a substrate support, and a method for manufacturing such a heat transfer assembly.

[0010]

[0010] According to a first aspect of the present invention, a heater assembly used on a generally cylindrical substrate support, A first heater unit configured to be fixed to the circumferential surface of the substrate support, It comprises a second heater section configured to be fixed to the circumferential surface of the substrate support, A heater assembly is provided in which the first end of the first heater section and the second end of the second heater section are configured to overlap in the axial direction of the substrate support when fixed to the circumferential surface.

[0011]

[0011] According to a second aspect of the present invention, a substrate support configured to support a substrate is provided, comprising a heater assembly according to the first aspect.

[0012]

[0012] According to a third aspect of the present invention, a lithography apparatus is provided that includes a substrate support according to the second aspect.

[0013]

[0013] According to a fourth aspect of the present invention, a method for supporting a substrate is provided, which includes the use of a substrate support according to the second aspect.

[0014]

[0014] A fifth aspect of the present invention provides a method for performing lithography, comprising projecting a radiation beam onto a substrate during an exposure operation, wherein the substrate is supported by a substrate support according to the second aspect.

[0015]

[0015] Further embodiments, features and advantages of the present invention, as well as the structure and operation of various embodiments, features and advantages of the present invention will be described in detail below with reference to the accompanying drawings. [Brief explanation of the drawing]

[0016]

[0016] Next, embodiments of the present invention will be described as merely examples with reference to the attached schematic diagrams. In the drawings, corresponding reference symbols indicate corresponding parts.

[0017] [Figure 1] This provides a general overview of a lithography system. [Figure 2] A cross-sectional view of a substrate support not related to the present invention is shown. [Figure 3] A schematic diagram of a substrate support with a heater assembly is shown inverted. [Figure 4] A magnified and schematic view of a portion of the substrate support in Figure 3 is shown. [Figure 5] A schematic diagram of a portion of the heater assembly according to the first embodiment is shown. [Figure 6]Schematically shows a part of a heater assembly according to a second embodiment. [Figure 7] Schematically shows a part of a heater assembly according to a third embodiment. [Figure 8] Schematically shows a part of a heater assembly according to a fourth embodiment. [Figure 9] Schematically shows a part of a heater assembly according to a fifth embodiment. [Figure 10] Schematically shows a part of a heater assembly according to a sixth embodiment.

[0018] The features shown in the drawings are not necessarily to scale, and the sizes and / or configurations shown are not limiting. It will be understood that the drawings may include optional features that may not be essential to the invention. Also, not all features of the device are shown in each drawing, and in some cases only a part of the components relevant to the description of a particular feature may be shown.

Embodiments for Carrying Out the Invention

[0019]

[0017] In this document, the terms "radiation" and "beam" are used to encompass all types of electromagnetic radiation including ultraviolet light (having wavelengths such as 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm).

[0020]

[0018] The terms "reticle", "mask", or "patterning device" as used herein can be construed broadly to refer to a general-purpose patterning device that can be used to provide a patterned cross-section to an incoming radiation beam corresponding to a pattern created on a target portion of a substrate. The term "light valve" can also be used in this context. Examples of such patterning devices other than classical masks (transmission or reflection masks, binary masks, phase-shift masks, hybrid masks, etc.) include programmable mirror arrays and programmable LCD arrays.

[0021]

[0019] Figure 1 schematically depicts a lithographic apparatus. The lithographic apparatus includes an illumination system (also referred to as an illuminator) IL configured to condition a radiation beam B (e.g., UV radiation or DUV radiation), a mask support (e.g., a mask table) MT constructed to support a patterning device (e.g., a mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA in accordance with certain parameters, a substrate support (e.g., a substrate table) WT constructed to hold a substrate (e.g., a resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate support WT in accordance with certain parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., including one or more dies) of the substrate W.

[0022]

[0020] During operation, the illumination system IL receives the radiation beam B from a radiation source SO, e.g., via a beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for directing, shaping, and / or controlling the radiation. The illuminator IL may be used to condition the radiation beam B such that its cross-section has a desired spatial and angular intensity distribution in the plane of the patterning device MA.

[0023]

[0021] As used herein, the term “projection system” PS should be interpreted broadly to encompass various types of projection systems, including refractive optical systems, reflective optical systems, reflective-refractory optical systems, anamorphic optical systems, magneto-optical systems, electromagnetic optical systems, and / or electrostatic optical systems, or any combination thereof, as appropriate in accordance with the exposure radiation used and / or other factors such as the use of immersion liquid or vacuum. Where the term “projection lens” is used herein, it can be considered synonymous with the more general term “projection system” PS.

[0024]

[0022] The lithography apparatus is of a type in which at least a portion of the substrate W is covered with an immersion liquid having a relatively high refractive index, such as water, so as to fill the immersion space between the projection system PS and the substrate W, and this is also called immersion lithography. Further information on immersion technology is described in U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0025]

[0023] The lithography apparatus may be of a type that has two or more substrate support WTs (also called a “dual-stage”). In such a “multi-stage” machine, the substrate support WTs may be used in parallel, and / or, while a substrate W on one substrate support WT is being used to expose a pattern onto that substrate W, a preparation step for subsequent exposure of the substrate W may be performed on a substrate W located on another substrate support WT.

[0026]

[0024] In addition to the substrate support WT, the lithography apparatus may include a measurement stage (not shown). The measurement stage is positioned to hold sensors and / or cleaning devices. Sensors may be positioned to measure the characteristics of the projection system PS or the characteristics of the radiated beam B. The measurement stage may hold multiple sensors. Cleaning devices may be positioned to clean parts of the lithography apparatus, such as a part of the projection system PS or a part of the system that provides the immersion fluid. The measurement stage may move below the projection system PS when the substrate support WT is away from the projection system PS.

[0027]

[0025] During operation, the radiating beam B is incident on a patterning device MA, such as a mask held on a mask support MT, and a pattern is formed by the pattern (design layout) present on the patterning device MA. The radiating beam B, having crossed the mask MA, passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. Using a second positioner PW and a position measuring system IF, the substrate support WT can be precisely moved to position various target portions C at focused and aligned positions within the path of the radiating beam B. Similarly, a first positioner PM and optionally another position sensor (not explicitly shown in Figure 1) may be used to precisely position the patterning device MA relative to the path of the radiating beam B. The patterning device MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. The illustrated substrate alignment marks P1, P2 occupy dedicated target portions, but may be located in the space between target portions. When substrate alignment marks P1 and P2 are located between target portions C, they are called scribe line alignment marks.

[0028]

[0026] To clarify the present invention, the Cartesian coordinate system is used. The Cartesian coordinate system has three axes, namely the x-axis, y-axis, and z-axis. Each of the three axes is orthogonal to the other two axes. A rotation about the x-axis is called an Rx rotation. A rotation about the y-axis is called a Ry rotation. A rotation about the z-axis is called an Rz rotation. The x-axis and y-axis define the horizontal plane, while the z-axis is perpendicular. The Cartesian coordinate system is used only for clarification and not to limit the present invention. Alternatively, another coordinate system, such as a cylindrical coordinate system, may be used to clarify the present invention. The orientation of the Cartesian coordinate system may be different, for example, such that the z-axis has a component along the horizontal plane.

[0029]

[0027] Immersion technology has been introduced into lithography systems to enable improved resolution of smaller features. In an immersion lithography apparatus, a liquid layer of immersion fluid having a relatively high refractive index is interposed in the immersion space between the apparatus's projection system PS (the patterned beam is projected through the projection system PS toward the substrate W) and the substrate W. The immersion fluid covers at least the portion of the substrate W below the final element of the projection system PS. Thus, at least the portion of the substrate W that is exposed is immersed in the immersion fluid.

[0030]

[0028] In commercial immersion lithography, the immersion fluid is water. Typically, the water is highly purified distilled water, such as ultrapure water (UPW), which is commonly used in semiconductor manufacturing plants. In immersion systems, UPW is often purified and may undergo additional processing steps before being supplied to the immersion space as the immersion fluid. In addition to water, other liquids with a high refractive index, such as hydrocarbons including fluorinated hydrocarbons, and / or aqueous solutions, can be used as the immersion fluid. It is also conceivable that other fluids other than liquids may be used in immersion lithography.

[0031]

[0029] In this specification, local immersion refers to a situation in which, during use, the immersion fluid is confined to an immersion space between the final element and the surface facing the final element. This opposing surface is the surface of the substrate W, or the surface of a support stage (or substrate support WT) that is coplanar with the surface of the substrate W. (Note that, in the following text, when referring to the surface of the substrate W, unless otherwise specified, the surface of the substrate support WT is also referred to, and vice versa.) A fluid handling structure IH located between the projection system PS and the substrate support WT is used to confine the immersion fluid to the immersion space. The immersion space, filled with the immersion fluid, is smaller than the top surface of the substrate W when viewed from above, and the immersion space remains substantially stationary relative to the projection system PS while the substrate W and substrate support WT move below.

[0032]

[0030] Other immersion systems are also envisioned, such as non-confined immersion systems (so-called "all-wet" immersion systems) and tank immersion systems. In non-confined immersion systems, the immersion liquid covers more than the surface beneath the final element. The liquid outside the immersion space exists as a thin liquid film. The liquid can cover the entire surface of the substrate W, or even the substrate W and the substrate support WT that is coplanar with the substrate W. In tank-type systems, the substrate W is completely immersed in a tank of immersion liquid.

[0033]

[0031] A fluid handling structure IH is a structure that supplies immersion fluid to an immersion space, removes immersion fluid from the immersion space, and thereby confines immersion fluid in the immersion space. It includes features that are part of a fluid supply system. The configuration disclosed in PCT Patent Application Publication WO99 / 49504 is an early fluid handling structure that includes a pipe that supplies or retrieves immersion fluid from the immersion space and operates in accordance with the relative motion of the stage below the projection system PS. In more recent designs, the fluid handling structure extends along at least a portion of the boundary of the immersion space between the final element of the projection system PS and the substrate support WT or substrate W so as to partially define the immersion space.

[0034]

[0032] The fluid handling structure IH may have a variety of functions. Each function may be derived from a corresponding feature that enables the fluid handling structure IH to achieve that function. The fluid handling structure IH may be referred to by several different terms, each referring to a single function, such as barrier members, sealing members, fluid supply systems, fluid removal systems, and liquid containment structures.

[0035]

[0033] The immersion liquid may be used as an immersion fluid. In that case, the fluid handling structure IH may be a liquid handling system. When referring to features defined in this paragraph in accordance with the preceding description, it can be understood that these features include features defined in relation to liquids.

[0036]

[0034] The lithography apparatus has a projection system PS. During exposure of the substrate W, the projection system PS projects a beam of patterned radiation onto the substrate W. To reach the substrate W, the path of the radiation beam B passes from the projection system PS through an immersion liquid confined by a fluid handling structure IH between the projection system PS and the substrate W. The projection system PS has a lens element at the end of the beam path, which is in contact with the immersion liquid. This lens element in contact with the immersion liquid may be referred to as the "final lens element" or "final element". The final element is at least partially surrounded by the fluid handling structure IH. The fluid handling structure IH can confine the immersion liquid below and on the opposite surface of the final element.

[0037]

[0035] As shown in Figure 1, the lithography apparatus includes a controller 50. The controller 50 is configured to control the substrate table WT.

[0038]

[0036] Figure 2 shows a part of a known lithography apparatus not relating to the present invention. The configuration shown in Figure 2 and described below can be applied to the lithography apparatus described above and shown in Figure 1. Figure 2 is a cross-sectional view of the substrate support 20 and the substrate W. The material of the substrate support 20 is not particularly limited, and any suitable material known in the art can be used. The substrate support 20 may preferably be formed from silicon-impregnated silicon carbide (SiSiC). Alternatively, the substrate support 20 may be formed from Zerodur™ (lithium aluminosilicate glass ceramic), cordierite, silicon carbide (SiC), or diamond SiSiC. The substrate support 20 is generally cylindrical, for example, a planar disc shape having a plane that is generally perpendicular to the cylindrical axis. The substrate support 2 is typically 200 mm, 300 mm, or 450 mm in diameter and may have a thickness of about 2 to 10 mm.

[0039]

[0037] In one embodiment, the substrate support 20 includes one or more control channels 61 of a thermal controller. A gap 5 exists between the edge of the substrate W and the edge of the substrate support 20. When the edge of the substrate W is imaged, or at other times such as when the substrate W first moves under the projection system PS (as described above), the immersion space filled with liquid by the fluid handling structure IH (for example) will pass at least partially over the gap 5 between the edge of the substrate W and the edge of the substrate support 20. This may cause liquid from the immersion space to enter the gap 5.

[0040]

[0038] The substrate W is held by a support body 21 (e.g., a pimple or purl table) having one or more purls 41 (i.e., protrusions from the surface). The support body 21 is an example of an object holder. Another example of an object holder is a mask holder. The negative pressure applied between the substrate W and the substrate support 20 helps to ensure that the substrate W is held firmly in place. However, if immersion liquid enters between the substrate W and the support body 21, it may cause difficulties, especially when unloading the substrate W.

[0041]

[0039] To deal with the immersion liquid entering the gap 5, at least one drain 10, 12 is provided on the edge of the substrate W to remove the immersion liquid entering the gap 5. In the example in Figure 2, two drains 10, 12 are shown, but there may be only one drain or more than two drains. In one embodiment, each of the drains 10, 12 is annular so as to surround the entire circumference of the substrate W.

[0042]

[0040] The primary function of the first drain 10 (located radially outward from the edge of the substrate W / support body 21) is to help prevent bubbles from entering the immersion space where the liquid of the fluid handling structure IH is present. Such bubbles can adversely affect imaging of the substrate W. The first drain 10 is present to help prevent gas in the gap 5 from escaping into the immersion space of the fluid handling structure IH. If gas escapes into the immersion space, bubbles may be formed floating in the immersion space. Such bubbles, if in the path of the projection beam, can cause imaging errors. The first drain 10 is configured to remove gas from the gap 5 between the edge of the substrate W and the edge of the recess in the substrate support 20 on which the substrate W is installed. The edge of the recess in the substrate support 20 may be optionally defined by a covering 101 separate from the support body 21 of the substrate support 20. In the x / y plane, the covering 101 may be molded as a ring and surround the outer edge of the substrate W. The first drain 10 primarily extracts gas and a very small amount of immersion liquid.

[0043]

[0041] The second drain 12 (located radially inward from the edge of the substrate W / support body 21) is provided to help prevent liquid advancing from the gap 5 under the substrate W from hindering the efficient release of the substrate W from the substrate table WT after imaging. Providing the second drain 12 reduces or eliminates problems that may arise due to liquid advancing under the substrate W.

[0044]

[0042] As shown in Figure 2, the lithography apparatus includes a first extraction channel 102 for passing a two-phase flow. The first extraction channel 102 may be formed within the support body 21 or in a component separate from the support body 21. The first and second drains 10 and 12 are each provided with their respective openings 107 and 117 and their respective extraction channels 102 and 113. The extraction channels 102 and 113 are in fluid communication with their respective openings 107 and 117 through their respective passages 103 and 114.

[0045]

[0043] As shown in Figure 2, the covering 101 has an upper surface. The upper surface extends circumferentially around the substrate W on the support body 321. When the lithography apparatus is in use, the substrate support 20 moves relative to the fluid handling structure IH. During this relative movement, the fluid handling structure IH passes through the gap 5 between the covering 101 and the substrate W. In one embodiment, the relative movement is caused by the substrate support 20 moving under the fluid handling structure IH. In an alternative embodiment, the relative movement is caused by the fluid handling structure IH moving on top of the substrate support 20. In a further alternative embodiment, the relative movement is provided by both the movement of the substrate support 20 under the fluid handling structure IH and the movement of the fluid handling structure IH on top of the substrate support 20. In the following description, movement of the fluid handling structure IH is used to mean the relative movement of the substrate support 20 with respect to the fluid handling structure IH.

[0046]

[0044] Known designs of the covering 101 have a circular opening in plan view for receiving the substrate W. The opening has a fixed diameter. The diameter of the opening is designed to be larger than the diameter of the substrate W in all reasonably foreseeable situations. If the diameter of the opening is too small, the covering 101 may not be usable for the substrate W in all situations. The minimum allowable diameter of the opening depends on the diameter of the substrate W that the covering 101 is designed to surround and the required tolerances. Required tolerances include the manufacturing tolerance of the substrate W, the manufacturing tolerance of the opening of the covering 101, and variations in the diameter of the substrate W and the diameter of the opening of the covering 101 during use.

[0047]

[0045] The gap 5 between the covering 101 and the substrate W is created by an opening having a diameter larger than the diameter of the substrate W. In some places, the gap 5 may be about 200 μm. When the fluid handling structure IH passes through the gap 5, at least some of the immersion liquid flows through the gap 5. The flow of immersion liquid through the gap 5 increases the thermal load on the substrate W and the substrate support 20.

[0048]

[0046] As described above, thermal load can adversely affect the temperature stability of parts of the lithography apparatus. Such thermal load is undesirable because it can lead to thermal expansion or contraction of parts (e.g., substrate support 20, WT, or fluid handling structure IH), which can result in errors (e.g., overlay errors). Cooling load may occur due to undesirable evaporation of liquids. Such evaporation can occur, for example, by gas removal through the fluid handling structure IH, or by gas removal through the gap between the substrate W and the substrate support 20. Therefore, a heater assembly may be provided to control the temperature of parts of the lithography apparatus.

[0049]

[0047] Figure 3 shows a known heater assembly 500 configured to heat a substrate support 20. The heater assembly 500 includes a printed circuit board 502 and a plurality of heater units 504. The printed circuit board 502 and the plurality of heater units 504 are configured to be mounted on the substrate support 20. The plurality of heater units 504 are separate from the printed circuit board 502 and are electrically connected. In other words, the plurality of heater units 504 are not integrally formed with the printed circuit board 502. Figure 3 shows six heater units 504, but three of the heater units 504 are labeled. The heater units 504 may be provided in any number, such as three, four, eight, nine, or twelve.

[0050]

[0048] As shown in Figure 3, the substrate support 20 includes an upper opposing surface 508 and a lower opposing surface 510. In one embodiment, the upper opposing surface 508 is in the form of a substrate support region constructed and positioned on the substrate support 20 to support a substrate W (shown in Figure 1). The lower opposing surface 510 is constructed and positioned to engage with the inner surface 512 of the printed circuit board 502. In other words, the printed circuit board 502 is mounted on the lower opposing surface 510 of the substrate support 20, which is opposite to the upper opposing surface 508, i.e., the substrate support region. Thus, in practice, the heating assembly and substrate support 20 in Figure 3 are typically often used in the opposite orientation to that shown.

[0051]

[0049] As shown in Figure 3, the substrate support 20 may typically include a plurality of through holes 548 that allow pins (not shown) to pass through them in order to separate the substrate W from the substrate support area of ​​the substrate support 20, and / or allow negative pressure to be applied to the substrate W supported on the substrate support area during use to hold the substrate W in that area.

[0052]

[0050] The printed circuit board 502 may be a flexible printed circuit board. The printed circuit board 502 may include a plurality of mounting members 516 constructed and arranged to attach the inner surface 512 (shown in Figure 3) of the printed circuit board 502 to the lower opposing surface 510 of the board support 20. In the illustrated example, the plurality of mounting members 516 may include 18 mounting members 516 that are distributed substantially evenly along the printed circuit board 502. However, the number of mounting members 516 that are substantially distributed along the printed circuit board 502 is variable.

[0053]

[0051] The printed circuit board 502 may have multiple temperature sensors (not shown), such as PTC sensors or NTC sensors, for measuring the local temperature of the board support 20 and calculating the desired heating amount for each heater section 504. It is desirable to have multiple (for example, two, three, or more) temperature sensors for each heater section 504. The temperature sensors are conveniently placed on the mounting member 516.

[0054]

[0052] Although not shown, the mounting member 516 may include a mounting portion constructed and positioned to engage with an engaging member (not shown) located on the lower opposing surface 510 (shown in Figure 3) of the board support 20 in order to mount the printed circuit board 502 to the board support 20.

[0055]

[0053] The printed circuit board 502 may include a plurality of notched regions 524 constructed and positioned to engage with a plurality of protruding members 526 located on the lower opposing surface 510 of the board support 20 in order to align and mount the printed circuit board 502 to the board support 20. The plurality of notched regions 524 may include two notched regions 524, and the plurality of protruding members 526 may include two protruding members 526. However, the number of notched regions 524 that are generally aligned to the printed circuit board 502 may differ from the number of protruding members 526 that are generally aligned to the board support 20. The notched regions 524 may be generally semicircular in shape, and the protruding members 526 may be generally circular in shape. However, it should be understood that this is only an example of different types of shapes, configurations, and / or constructions of the protruding members 526 and notched regions 524 that can be provided.

[0056]

[0054] The printed circuit board 502 may include power terminals 544 that are constructed and arranged to supply power to the printed circuit board 502 and a plurality of heater units 504. In one embodiment, the power terminals 544 are connected to the annular portion 534 of the printed circuit board 502 using a flexible (or bendable) extension member 546.

[0057]

[0055] The heater assembly 500 may include six heater sections 504 that are positioned to substantially extend around the edge 514 of the substrate support area. However, the number of heater sections 504 that are positioned to substantially extend around the edge 514 of the substrate support area may vary. Each of the heater sections 504 may have an arc-shaped configuration. Each heater section 504 may include a heating resistor (not shown) that is constructed and positioned to generate heat, and the amount of heat generated by the heater section 504 is based on the amount of power supplied to the heating resistor. In one embodiment, the heater section 504 may be a cooling device that is constructed and positioned to cause cooling, such as a Peltier element. Thus, the heater section 504 may be described more generally as a heat transfer element, and the heater assembly may be described as a heat transfer assembly.

[0058]

[0056] Figure 4 is an enlarged view of a portion of a heater assembly similar to the heater assembly 500 in Figure 3. As shown in Figure 4, the connection of heat to the heater section 504 is provided by a small tab 547 connected to an annular section 534 of a printed circuit board 502 via a low-profile socket (not shown). Figure 4 also shows a meandering conductor 550 that forms a heating element that generates heat under the control of a controller.

[0059]

[0057] As is clear from Figure 4, the opposing ends 509 of adjacent heater sections 504a and 504b are generally parallel to the axis A of the cylindrical substrate support 20 (shown in Figure 3) (i.e., perpendicular to the support plane of the substrate W defined by the bar 41 of the substrate support 20) and separated by a small gap. Since each heater section 504 of the heater assembly 500 is individually controlled according to the heating load required to maintain each region of the substrate support 20 at the temperature set point, the amount of heat generated between adjacent heater sections 504 may differ. In extreme cases, one heater section 504 may be at maximum heat output while the adjacent heater section 504 is off. The difference in the amount of heat applied to the substrate support 20 by adjacent heater sections 504 creates a thermal gradient near the gap between adjacent heater sections 504. The gap may be about 1 to 2 mm. Despite the high thermal conductivity of the substrate support 20, a thermal gradient large enough to cause strain and / or stress may occur in the substrate support 20 and the substrate W held by the substrate support 20. Such stress and strain can lead to imaging errors such as overlay. A temperature gradient of about one-tenth of a Kelvin per millimeter may be sufficient to cause errors. It is desirable to reduce or eliminate such errors.

[0060]

[0058] Figure 5 schematically shows two heater sections 560a and 560b according to one embodiment of the present invention. Each of the heater sections 560a and 560b includes a main section 561 that extends along the cylindrical surface of the substrate support 20 when the heater section 560a and 560b are attached to the substrate support 20. Each end of the main section 561 is provided with projections 562 and 563 whose width in the direction parallel to the axial direction of the substrate support is smaller than the width of the main section 561 in the same direction. The first projection 562 of the projections 562 and 563 is provided on the upper side of the first end of the main section 561, and the second projection 563 of the projections 562 and 563 is provided on the lower side of the second end of the main section 561. The first projection 562 and the second projection 563 are complementary to each other.

[0061]

[0059] When the heater sections 560a and 560b are attached to the substrate support 20, the first projection 562 and the second projection 563 overlap the substrate support 20 in the axial direction. Preferably, the axial widths of the first and second projections 562 and 563 are equal. Preferably, the sum of the axial widths of the first and second projections 562 and 563 is substantially equal to the width of the main section 561, and a small gap is provided to accommodate installation tolerances and ensure electrical isolation of the first and second heater sections 562 and 563. Preferably, the intensity of the heating applied per unit area by the heater sections 560a and 560b is substantially uniform across the entire area of ​​the heater sections 560a and 560b.

[0062]

[0060] In the structure shown in Figure 5, when the first and second heater sections 560a and 560b are operating with different heat values, there is no abrupt transition between regions receiving different heat values, and an intermediate region is created that receives an average heat value, which we will refer to here as the overlapping region. For example, when the first heater section 560a is at maximum heat value and the second heater section 560b is at zero heat value, the overlapping region 564 receives half the heat value. This configuration reduces the temperature gradient within the substrate support 20, and reduces the strain and stress on the substrate W held by the substrate support 20.

[0063]

[0061] Figure 6 shows another embodiment that differs from the arrangement in Figure 5, except for the arrangement which reduces the temperature gradient within the substrate support 20 and, consequently, reduces the strain and stress on the substrate W held by the substrate support 20. Specifically, the embodiment shown in Figure 6 has heater sections 570c and 570b, each having protrusions 572, 573, and 574 in different arrangements at the ends of the main section 571 of the heater section 570a and 570b. In the arrangement of Figure 6, one end of each heater section 570a and 570b has a centrally located protrusion 572 that protrudes from the main section 571. The other end of the heater section 570a and 570b has two protrusions 573 and 574 located at the upper and lower ends of the end side of the main section 571. The first protrusion 572 is complementary to the second and third protrusions 573 and 574. Therefore, when the heater sections 570a and 570b are fixed to the circumferential surface of the substrate support 20, the first projection 572 of the heater section 570a fits between the second and third projections 573 and 574 of the second heater section 570b. The arrangement in Figure 6 has the same effect as the arrangement in Figure 5, namely, when the heater sections 570a and 570b are subjected to different amounts of heating, the overlapping region 576 applies an intermediate amount of heating, thereby reducing the circumferential heat gradient. The arrangement in Figure 6 also has the additional advantage of reducing the axial heat gradient.

[0064]

[0062] It should be understood that various other shapes can be applied to the ends of the heater sections in order to create an axial overlap between adjacent heater sections. Some further examples are shown in Figures 7 to 10, but it is of course possible to devise further arrangements based on the teachings described herein.

[0065]

[0063] Figure 7 shows an arrangement in which the ends of adjacent heater sections 580a and 580b are alternately arranged with complementary triangular protrusions 581 and 582. This arrangement has the advantage that the amount of heating in the overlapping region does not change in steps, but rather changes gradually in the circumferential direction, thus further reducing the heat gradient.

[0066]

[0064] Figure 8 shows an arrangement in which the ends of adjacent heater sections 590a and 590b have complementary curved edges 591 and 592. One end of each intersection has a convex curved edge 591, and the other end has a concave curved edge 592 with a complementary shape. Similar to the arrangement in Figure 7, the arrangement in Figure 8 can provide a more gradual transition in the amount of heating.

[0067]

[0065] Figure 9 shows an arrangement in which each heater section 595 has a parallelogram shape and its edge 596 is attached to the cylindrical surface, inclined with respect to the axial direction of the substrate support. The parallelogram shape can be considered as a rectangular main region and two triangular protrusions. Similar to the arrangements in Figures 7 and 8, this can provide a gentler transition in the amount of heating as it passes through the overlapping zone.

[0068]

[0066] Naturally, the above examples may be combined as desired, so it should be understood that temperature transitions between adjacent heater sections that provide different amounts of heat can be smoothed out by any method according to manufacturing convenience.

[0069]

[0067] Figure 10 shows that a similar effect can be obtained by alternating meandering heating wires 600a, 600b which are attached to a common heater substrate or directly to a substrate support. The currents I1, I2 flowing through the heating wires 600a, 600b are each individually controllable. In one embodiment, the main portion of each heater section includes a meandering heating wire connected to a long vertical wire and a short horizontal wire extending from the top to the bottom of the heater section. In the overlapping zone, each heater section has a plurality of horizontal extensions or fingers arranged alternately (or intersecting) with the extensions of adjacent heater sections. The overlapping portion can be thought of as resembling two interlocking combs. The portions of the meandering heating wires 600a, 600b that are arranged alternately with the meandering heating wires 600a, 600b of adjacent heater sections can be considered as protrusions. In such an arrangement, the thickness of the heating wires 600a and 600b in the overlapping areas (and therefore the resistance per unit length) may be adjusted to prevent overheating of the overlapping areas. Alternatively, if there are many meanders in the heating wires 600a and 600b of each heater section, only a portion of these meanders may be arranged alternately with adjacent heater sections. Other arrangements such as Greek key patterns or intersecting spiral patterns are also possible.

[0070]

[0068] It should be understood that the size of the overlapping region may depend, for example, on the number of heaters provided around the substrate support 20. If there are many heaters, the difference in the amount of heat applied by adjacent heaters is likely to be small, so it may be sufficient to make the overlapping region small. However, overall, the total circumferential length of the overlapping region is about 10% to 600%, preferably about 20% to 50%, of the circumference of the substrate support 20.

[0071]

[0069] To simplify manufacturing and assembly, it is desirable that all heater sections be identical. This means that one end of each heater section should be complementary to the other end of the heater section. In some arrangements, it is desirable that the heater sections have 180-degree rotational symmetry.

[0072]

[0070] The present invention may also provide a lithography apparatus. The lithography apparatus described above may have any or all of the other features or components. For example, the lithography apparatus may optionally include at least one of the following: a radiation source SO, an illumination system IL, a projection system PS, a substrate support WT, etc.

[0073]

[0071] Specifically, the lithography apparatus may include a projection system PS configured to project the radiation beam B toward a region of the surface of the substrate W. The lithography apparatus may further include the substrate supports 300, 400, 500 described in any of the above embodiments and modifications.

[0074]

[0072] Embodiments include the following numbered clauses: 1. A heater assembly used on a generally cylindrical substrate support, A first heater unit configured to be fixed to the circumferential surface of the substrate support, It comprises a second heater section configured to be fixed to the circumferential surface of the substrate support, A heater assembly in which the first end of the first heater section and the second end of the second heater section are configured to overlap in the axial direction of the substrate support when fixed to the circumferential surface. 2. The first heater section has a first main section, and the first end section has a first projection that is smaller in the axial direction than the first main section, and The second heater section has a second main section, and the second end section has a second projection that is smaller in the axial direction than the second main section. The heater assembly according to Clause 1, wherein the first and second projections are configured to be adjacent in the axial direction when fixed to the circumferential surface. 3. The heater assembly according to Clause 2, wherein the first and second projections have equal width in the axial direction. 4. The heater assembly according to Clause 2, wherein the second end further comprises a third projection having a smaller axial width than the second main portion, and the first, second, and third projections are configured such that, when fixed to a circumferential surface, the first projection is located axially between the second and third projections. 5. The heater assembly according to Clause 4, wherein the axial width of the first projection is substantially equal to the sum of the axial widths of the second and third projections. 6. The heater assembly according to any one of the clauses 1 to 5, wherein the edges of the first and second ends are inclined at an acute angle with respect to the axial direction. 7. A heater assembly as described in Clause 6, wherein the acute angle is in the range of 20° to 70°, preferably in the range of 30° to 60°. 8. A heater assembly according to any one of the clauses 1 to 7, wherein the edges of the first and second ends are curved. 9. The heater assembly according to any one of the clauses 1 to 8, wherein each of the first and second heater sections comprises a meandering heating wire. 10. The heater assembly according to Clause 9, wherein a portion of the meandering heating wire of the first heater section is arranged alternately with a portion of the meandering heating wire of the second heater section. 11. The heater assembly according to Clause 9 or 10, wherein the meandering heating wire has a heating rate per unit length that varies along its length. 12. The heater assembly according to any one of the clauses 1 to 11, wherein the first heater section has a second end corresponding to the shape of the second end of the second heater section, and the second heater section has a first end corresponding to the shape of the first end of the first heater section. 13. A heater assembly according to any one of the clauses 1 to 12, comprising four, preferably eight, heater sections. 14. A heater assembly according to any of clauses 1 to 13, wherein the number of heater units is less than 16, preferably less than 12. 15. A heater assembly as described in any of clauses 1 to 14, wherein the heater section is independently controllable. 16. A heater assembly described in any of clauses 1 to 15, wherein the heater section is substantially identical. 17. A substrate support configured to support a substrate, comprising a generally cylindrical body and a heater assembly as described in any of clauses 1 to 16, wherein the first and second heater portions are fixed to the circumferential surface of the substrate support. 18. A substrate support according to Clause 16, wherein the main body is formed from silicon-impregnated silicon carbide (SiSiC), lithium aluminosilicate glass ceramic, Zerodur, cordierite, silicon carbide (SiC), or diamond SiSiC. 19. A lithography apparatus comprising a substrate support as described in Clause 17 or 18. 20. The lithography apparatus according to Clause 19, further comprising a control system arranged to independently control the thermal output of the heater section. 21. A method for performing lithography, The exposure operation includes projecting a radiation beam onto the substrate, The substrate is supported by the substrate support described in Clause 17 or 18, method.

[0075]

[0073] Although this text specifically refers to the use of lithography equipment in the manufacture of ICs, it should be understood that lithography equipment described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, and the like.

[0076]

[0074] Although embodiments of the present invention are referred to in the context of lithography apparatus in this text, embodiments of the present invention may be used in other apparatuses. Embodiments of the present invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus for measuring or processing objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatuses may generally be referred to as lithography tools.

[0077]

[0075] Although the above has specifically referred to the use of embodiments of the present invention in the context of photolithography, it will be understood that the present invention is not limited to photolithography where permitted in the context.

[0078]

[0076] Where permitted by context, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored in a machine-readable medium that can be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM), random access memory (RAM), magnetic storage media, optical storage media, flash memory devices, propagating signals of electrical, optical, acoustic or other forms (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Firmware, software, routines, and instructions may also be described herein as performing specific actions. However, it should be understood that such descriptions are merely for convenience, and that such actions actually result from a computing device, processor, controller, or other device that executes the firmware, software, routines, instructions, etc., and that in execution, actuators or other devices may interact with the material world.

[0079]

[0077] Although specific embodiments of the present invention have been described above, it will be understood that the present invention can be implemented in ways other than those described. The above description is for illustrative purposes only and is not limiting. Accordingly, it will be apparent to those skilled in the art that modifications to the described invention can be made without departing from the following claims.

Claims

1. A heater assembly used on a generally cylindrical substrate support, A first heater unit configured to be fixed to the circumferential surface of the substrate support, It comprises a second heater portion configured to be fixed to the circumferential surface of the substrate support, A heater assembly in which the first end of the first heater portion and the second end of the second heater portion are configured to overlap in the axial direction of the substrate support when fixed to the circumferential surface.

2. The first heater portion has a first main portion, and the first end portion has a first projection that is smaller in width in the axial direction than the first main portion. The second heater portion has a second main portion, and the second end portion has a second projection that is smaller in width in the axial direction than the second main portion. The heater assembly according to claim 1, wherein the first and second protrusions are configured to be adjacent in the axial direction when fixed to the circumferential surface.

3. The first and second projections have equal width in the axial direction, or the second end further comprises a third projection having a smaller width in the axial direction than the second main portion. The first, second, and third protrusions are configured such that, when fixed to the circumferential surface, the first protrusion is located between the second and third protrusions in the axial direction. Preferably, the heater assembly according to claim 2, wherein the width of the first projection in the axial direction is substantially equal to the sum of the widths of the second and third projections in the axial direction.

4. The edges of the first and second ends are inclined at an acute angle with respect to the axial direction, and / or The edges of the first and second ends are curved and / or The heater assembly according to any one of claims 1 to 3, wherein each of the first and second heater sections is provided with a meandering heating wire.

5. The acute angle is in the range of 20° to 70°, preferably in the range of 30° to 60°, and / or A portion of the meandering heating wire of the first heater section is arranged alternately with a portion of the meandering heating wire of the second heater section, and / or The heater assembly according to claim 4, wherein the meandering heating wire has a heating amount per unit length that varies along its length.

6. The first heater section has a second end corresponding to the shape of the second end of the second heater section, The heater assembly according to any one of claims 1 to 5, wherein the second heater portion has a first end corresponding to the shape of the first end of the first heater portion.

7. It comprises four, preferably eight, heater units, and / or The heater assembly according to any one of claims 1 to 6, wherein the number of heater units is less than 16, preferably less than 12.

8. The heater unit is independently controllable and / or The heater assembly according to any one of claims 1 to 7, wherein the heater section is substantially the same.

9. A substrate support configured to support a substrate, It comprises a generally cylindrical body and a heater assembly according to any one of claims 1 to 8, The first and second heater sections are fixed to the circumferential surface of the substrate support, which is a substrate support.

10. The substrate support according to claim 9, wherein the main body is formed from silicon-impregnated silicon carbide (SiSiC), lithium aluminosilicate glass ceramic, Zerodur, cordierite, silicon carbide (SiC), or diamond SiSiC.

11. A lithography apparatus comprising the substrate support described in claim 9 or 10.

12. The lithography apparatus according to claim 11, further comprising a control system arranged to independently control the heat output of the heater section.

13. A method for performing lithography, The exposure operation includes projecting a radiation beam onto the substrate, The method wherein the substrate is supported by the substrate support described in claim 9 or 10.

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