WO2009032197A1

WO2009032197A1 - Glass-ceramic and glass-ceramic/ceramic composite semiconductor manufacturing article support devices

Info

Publication number: WO2009032197A1
Application number: PCT/US2008/010253
Authority: WO
Inventors: Douglas M. Beall; Michael W. Linder; Marcus R. Serwazi; Lothar Wondraczek
Original assignee: Corning Incorporated
Priority date: 2007-08-31
Filing date: 2008-08-29
Publication date: 2009-03-12
Also published as: TW200932693A

Abstract

Disclosed is an article support or handling material configured to support an article to be placed in a beam path of a radiation beam of a lithographic apparatus. The article support or handling material comprises a glass-ceramic material which exhibits a fracture toughness of greater than 1.5 MPa/m1/2, a thermal expansion of less than 1.0×10-6K-1, a thermal conductivity greater than about 3.5 W/(m.K), an elastic modulus of greater than 120 GPa, a high elastic-to-density ratio in excess of 40 GPa cm³/g, and a thermal stability coefficient ≤ 0.25. In one embodiment this glass-ceramic material is a cordierite glass-ceramic material.

Description

GLASS-CERAMIC AND GLASS-CERAMIC/CERAMIC COMPOSITE SEMICONDUCTOR MANUFACTURING ARTICLE SUPPORT DEVICES

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 1 19(e) of U.S. Provisional Application Serial No. 60/9671 1 1 filed on August 31, 2007.

BACKGROUND

Field of the Disclosure

[0001] The present invention relates to a lithographic apparatus comprising an article support configured to support an article to be placed in a beam path of radiation of the lithographic apparatus. More particularly, the invention relates to a glass-ceramic and layered glass-ceramic/ceramic article support structures.

Technical Background

[0002] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning structure, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation- sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known 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 through a radiation beam in a given direction (the "scanning"-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning structure to the substrate by imprinting the pattern onto the substrate. [0003] In the lithographic apparatus as hereabove specified, an article to be placed in the radiation beam is held to an article support, for example, by a clamping electrode, by vacuum suction or otherwise. Electrostatic clamping may be used for example when a substrate is processed in vacuum conditions. This type of processing occurs for instance when the type of irradiation used for photolithographic processes is in the (soft) x-ray region, also referred to as the extreme ultraviolet (EUV) region.

[0004] Currently, article supports are typically made from a variety of rigid materials, including for instance materials such as ULE® glass, Zerodur glass-ceramic, Cordierite ceramic or Sapphire crystalline material, as well as rigid ceramic and crystalline materials. These materials are chosen among others for good mechanical stability and heat conductivity and reduced thermal expansion properties.

[0005] Typically, for these materials, a number of mechanical and material properties are considered important, and where typically one material has a better mechanical stability, it may have relatively less favorable thermal expansion properties compared to another material. In particular, the cordierite ceramic, Zerodur glass-ceramic and ULE® glass materials, have good thermal characteristics in that they have a coefficient of thermal expansion (CTE) of practically zero. This makes these materials attractive for use as substrate table materials, since (local) heating of these materials does not give rise to significant distortions, which can result in a deteriorated focus and/or overlay of the images projected on a target portion of a substrate. However, the wear characteristics of these materials are such that the economic lifetime of article support made from those materials is significantly limited in comparison with other materials that are known, such as SiSiC or SiC, but which possess less favorable thermal expansion characteristics.

[0006] Hence, there is need for a handling material and, particularly an article support material that combines the best of these characteristics in one material. Stated differently, the semiconductor market requires a handling/support material which is very stable, stiff, wear resistant, and exhibits a low coefficient of thermal expansion and a high thermal conductivity.

SUMMARY

[0008] One aspect of the invention described herein is an article support or handling material configured to support an article to be placed in a beam path of a radiation beam of a iitnograpnic apparaτus. i ne aπicie suppoπ or nanαnng material comprises a giass-ceramic material which exhibits a fracture toughness greater than 1.5 MPa/m^1/2, a thermal expansion of less than 1.Ox 10^"6K^'1, a thermal conductivity greater than about 3.5 W/(m K), an elastic modulus of greater than 120 GPa, a high elastic-to-density ratio in excess of 40 GPa g/cm³ and a thermal stability coefficient < 0.25. In one embodiment this glass-ceramic material is a cordierite glass-ceramic material.

[0009] Another aspect of the invention provides for an article support which is comprised of a layered configuration. The top layer is comprised of glass-ceramic material layer wherein the material exhibits a fracture toughness greater than 1.5 MPa/m^1/2 , a coefficient of thermal expansion of less than 1.0^χ l 0^'6K^"1, a thermal conductivity greater than about 3.5 W/(m-K), an elastic modulus of greater than 120 GPa and a high elastic-to-density ratio in excess of 40 GPa-g/cm³ and a thermal stability coefficient < 0.25. The middle layer is comprised of a honeycomb ceramic material while the bottom layer comprises a glass- ceramic material layer. In one embodiment this bottom glass-ceramic layer is exhibits the same or similar properties as that exhibited by the top layer and thus is comprised of the same cordierite glass-ceramic material.

[0010] In the context of this application, the "article" may be any of a substrate (e.g., a wafer), a patterning structure (e.g., a reticle or mask), or any other article (e.g., optical element) that is held in the radiation path of a radiation system, and more specifically may be a substrate to be processed in manufacturing devices employing lithographic projection techniques and/or a lithographic projection mask or mask blank for use in a lithographic projection apparatus, a mask handling apparatus such as mask inspection or cleaning apparatus, or a mask manufacturing apparatus

[0011] Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. [0012] It is to be understood that both the foregoing general description and the following detailed description present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description, serve to explain the principles and operations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 depicts a lithographic apparatus according to an embodiment of the invention; and,

[0014] FIG. 2 schematically illustrates an alternative design of an article support according to an embodiment of the invention; and,

[0015] FIG. 3 schematically illustrates one embodiment of the honeycomb layer portion of the alternative design article support; and

[0016] FIG. 4 schematically illustrates a second embodiment of the honeycomb layer portion of the alternative design article support.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 schematically depicts a lithographic apparatus which incorporates the article support invention described herein.

[0018] The lithographic apparatus comprises the following features: (1) an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV radiation or EUV radiation); (2) a support structure (e.g. a mask table) MT constructed to support a patterning structure (e.g. a mask) MA and connected to a first positioner/stage PM configured to accurately position the patterning structure in accordance with certain parameters; (3) a substrate table (e.g. a wafer table) WT constructed to hold a substrate (e.g. a resist-coated wafer) W and connected to a second positioner/stage PW configured to accurately position the substrate in accordance with certain parameters; and, (4) a projection system (e.g. a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by patterning structure MA onto a target portion C (e.g. comprising one or more dies) of the substrate W.

[0019] The illumination system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping, or controlling radiation. [0020] The support structure holds the patterning structure in a manner that depends on the orientation of the patterning structure, the design of the lithographic apparatus, and other conditions, such as tor example whether or not the patterning structure is heiα in a vacuum environment. The support structure can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning structure. The support structure may be a frame or a table, for example, which may be fixed or movable as required. The support structure may ensure that the patterning structure is at a desired position, for example with respect to the projection system. Any use of the terms "reticle" or "mask" herein may be considered synonymous with the more general term "patterning structure."

[0021] The term "patterning structure" used herein should be broadly interpreted as referring to any device that can be used to impart a radiation beam with a pattern in its cross- section such as to create a pattern in a target portion of the substrate. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so called assist features. Generally, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit.

[0022] The patterning structure may be transmissive or reflective. Examples of patterning structures include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in a radiation beam which is reflected by the mirror matrix. [0023] The term "projection system" used herein should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered as synonymous with the more general term "projection system". [0024] As here depicted, the apparatus is of a reflective type (e.g. employing a reflective mask). Alternatively, the apparatus may be of a transmissive type (e.g. employing a transmissive mask). 008/010253

[0025] The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and/or two or more support structures). In such "multiple stage" machines the additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposure. [0026] The lithographic apparatus may also be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g. water, so as to fill a space between the projection system and the substrate. An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. The term "immersion" as used herein does not 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. [0027] Referring to FIG. 1, the illuminator DL receives a radiation beam from a radiation source SO. The source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In such cases, the source is not considered to form part of the lithographic apparatus and the radiation beam is passed from the source SO to the illuminator IL with the aid of a beam delivery system BD comprising, for example, suitable directing mirrors and/or a beam expander. In other cases the source may be an integral part of the lithographic apparatus, for example when the source is 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.

[0028] The illuminator IL may comprise an adjuster AD for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer and/or inner radial extent (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. In addition, the illuminator IL may comprise various other components, such as an integrator IN and a condenser CO. The illuminator may be used to condition the radiation beam, to have a desired uniformity and intensity distribution in its cross-section.

[0029] The radiation beam B is incident on the patterning structure (e.g., mask) MA, which is held on the support structure (e.g., mask table) MT, and is patterned by the patterning structure. Having traversed the patterning structure MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner/stage PW and position sensor IF2 (e.g. an interferometric device, linear encoder or capacitive sensor), the substrate table WT can be moved accurately, e.g. so as to position different target portions C in the path of the radiation beam B. Similarly, the first positioner/stage PM and another position sensor IFl can be used to accurately position the patterning structure MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library, or during a scan. In general, movement of the support structure MT may be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner/stage PM. Similarly, movement of the substrate table WT may be realized using a long-stroke module and a short-stroke module, which form part of the second positioner/stage 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. Patterning structure MA and substrate W may be aligned using patterning structure alignment marks Ml, M2 and substrate alignment marks Pl, P2. Although the substrate alignment marks as illustrated occupy dedicated target portions, they may be located in spaces between target portions (these are known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the patterning structure MA, the patterning structure alignment marks may be located between the dies.

[0030] Designing article supports such as substrate/wafer tables, mask supports and positioner/stages (mentioned above) in a lithographic system can be a very critical process. In the following description, the embodiments will be referred to as substrate/wafer tables, mask supports or and positioner/stages, although it should be understood that these embodiments may also be referred to or considered as the more general indication of "article support". Specifically, in the context of an embodiment of this invention, the article supports may form any support configured to hold an article in a beam of radiation, be it a substrate, a mask or a fiducial reticle.

[0031] Conventional material options for article supports or substrate/wafer tables are numerous, each of which exhibiting a number of shortcomings which make their use in these applications less than desirable. One conventional material option utilized is the use of materials having very low coefficients of thermal expansion coupled with abrasion-resistant coatings on the surface on the side which is exposed to the silicon wafer or mask. Although an improvement over non-coated materials, these laminate/coated materials still do not exhibit the sufficient wear resistance that is desired by the semiconductor industry. Specifically, these laminated abrasion-resistant coated materials still do not exhibit a sufficiently high wear resistance to withstand the wear caused by the hard silicon wafers placed thereon and the pressure typically placed on the article supports in the standard lithography process, particularly due to the localized pressure which may result due to particle contamination. As such, the lifetimes laminated abrasion-resistant coated materials is far less than that desired in the lithography industry.

[0032] Another conventional material option involves the use of much harder materials, for example silicon-infiltrated silicon carbide (Si:SiC), exhibiting high initial elastic modulus. The shortcoming associated with these high modulus materials is the high coefficients of thermal expansion they exhibit is problematic; complicated on line monitoring and alignment of the wafer is required to actively compensate dimensional changes. One additional conventional material option involves foamed materials, particularly SiC. However, such foams are usually difficult to produce in large sizes, are expensive to produce and they possess undesirably large coefficients of thermal expansion. Although they may meet the criterion of mechanical stiffness and high elastic modulus-to-density ratio, respectively, their thermal properties, particularly conductivity and expansion, are unacceptable. Furthermore, foamed materials are particularly susceptible to particle contamination when utilized as semiconductor support materials.

[0033] In order to address the shortcomings of the aforementioned material options, the inventors have designed an improved article support configured to support an article to be placed in a beam path of a radiation beam of a lithographic apparatus. The article support, in its most general form, comprises a glass-ceramic material which possesses the following desirable attributes: (1) fracture toughness greater than 1.5 MPa/m^l/2 (2) a coefficient of thermal expansion of less than 1.OxIC⁶K^'1; (3) a thermal conductivity greater than about 3.5 W/(m-K); (4) an elastic modulus of greater than 120 GPa; and (5) a high elastic modulus-to- density ratio in excess of 40 GPa-g/cm³; and, (6) a thermal stability coefficient of < 0.25. [0034] Any glass-ceramic which exhibits the aforementioned desirable properties will be suitable for use as the article support material. In one embodiment, a glass-ceramic material exhibiting cordierite (2 MgO.2Al₂θ3.5SiO₂) as the predominate crystalline phase, is the glass- ceramic material utilized. [0035] Desirably, the glass-ceramic support material is essentially non-porous which leads to increased wear resistance and fracture toughness, however the support should not be so dense that the glass-ceramic material, does not exhibit the requisite/aforementioned modulus to density ratio requirement. That said, the skilled artisan will recognize that if the glass-ceramic material is non-porous/dense that characteristic must be balanced by a high enough elastic modulus so as to achieve the requisite modulus to density ratio requirement in excess of 40 GPa g/cm³.

[0036] Regarding the thermal stability coefficient (TSC) of less than or equal to 0.25, it is measure of the desired relationship between the coefficient of thermal expansion (CTE) and the thermal conductivity (TC) and is defined by the following formula:

TSC= CTE / log (10) [TC ^• Im-K / W]

This TSC relationship takes into account that a that a low CTE is most desirable for the glass- ceramic support material for a material, while a high thermal conductivity, though important is less critical, thus the thermal conductivity portion of the ratio includes the LOGlO modifier. By way of example, SiC and Si₃ N₄ exhibit undesirably high thermal stability coefficients of 0.1 and 2.1 respectively.

[0037] Referring to FIG. 2 illustrated therein is another embodiment of the article support structure 10 which comprises a layered or laminate structure which includes a top glass- ceramic material layer 12, a middle layer 16 comprising a honeycomb ceramic material, and a bottom layer 16 comprised of a glass-ceramic, ceramic or crystalline material. In one embodiment, the top layer is comprised of the aforementioned glass-ceramic material that exhibits the aforementioned desirable properties. In one particular embodiment the glass- ceramic material top layer comprises a glass-ceramic material exhibiting cordierite (2MgO.2Al₂O₃.5SiO₂) as the predominate crystalline phase. As in the previous non-layered embodiment this cordierite glass-ceramic material exhibits a fracture toughness greater than 1.5 MPa/m^1/2, a coefficient of thermal expansion of less than 1.OxIC⁶K^"1, a thermal conductivity greater than about 3.5 W/(m.K), an elastic modulus of greater than 120 GPa, a high elastic-to-density ratio in excess of 40 GPa g/cm³ and a thermal stability coefficient of less than or equal to 0.25. There is no limitation on the thickness of this top cordierite glass ceramic layer, however if the layer is too thick, the weight of the overall layered structure is unacceptable; that said, it is recommended that this top glass-ceramic layer exhibit a thickness of 5 mm or less. [0038] Preferably, the bottom layer exhibits the same or similar properties as that exhibited by the top layer and thus is comprised of the same cordierite glass-ceramic material. It is contemplated however that materials other than cordierite glass ceramics can be utilized for this bottom layer including, for example, the following thermally conductive, stiff and abrasion resistant glass-ceramic, ceramic or crystalline materials such as sintered cordierite, silicon carbide, silicon nitride, aluminum nitride, aluminum titanate, boron nitride. [0039] It should be noted that in this layered configuration/embodiment the inner or middle ceramic honeycomb layer functions to give the article support the requisite stiffness, while the top glass-ceramic comprised of the cordierite glass ceramics functions to enable heat transfer from the article (either the wafer or the mask) which ensures thermal stability of the wafer/mask and enables precise positioning and handling during the semiconductor manufacturing operation. Additionally, the top cordierite glass ceramic layer has the following functions: 1) it provides a seal for the open channels in the honeycomb substrate layer; 2) it provide a homogeneous surface of very high quality, which enables the precision machining and micro- to nanostructuring of that surface, which in turn leads to , and 3) improved mechanical resistance of the table.

[0040] Referring specifically to the inner honeycomb layer portion 14 (Fig. 2) of the layered article support embodiment, it is contemplated that this honeycomb substrate can be comprised of either extruded aluminum titanate and/or cordierite ceramic materials; see US Pat. No. 5258150 for a suitable cordierite material and US Pat. No. 7001861 for a suitable aluminum titanate material. Commercially available materials suitable for this use include the following materials manufactured by the assignee of the current invention: Celcor^®, Duratrap^®AT, Duratrap^®CO or Duratrap^® RC. In a preferred embodiment the top plate is comprised a glass-ceramic material exhibiting cordierite as the predominate crystalline phase glass ceramic and the honeycomb substrate middle layer is comprised of cordierite ceramics; the use of two cordierite materials ensures that less problems with incompatibility of the materials.

[0041] This honeycomb substrate layer can be comprised of a single extruded honeycomb substrate as illustrated in Fig. 3. Referring to Fig. 4, illustrated is an alternative embodiment of the honeycomb substrate layer 14 comprising of a plurality of extruded honeycomb segments 20 affixed together as illustrated in For ease of manufacturing, a the single piece honeycomb substrate layer is preferred, however for larger sizes, an assembly of a plurality of segments may be necessary. Depending on the desired geometry of the article support, segments of different shapes can be utilized; triangular segments (see Fig. 4), hexagonal segments (not shown), quadratic segments (not shown) or a combination of those segment shapes (not shown) are possible.

[0042] Referring again to Fig. 2, the layered article support 10 embodiment further includes a bonding layer 18 which functions to bond together the upper cordierite glass ceramic 12 and the bottom glass-ceramic layer 16 to the inner honeycomb substrate layer 14. In one embodiment this bonding layer comprises a layer of an inorganic glass frit which exhibits a sintering temperature not higher than 900 ⁰C; additionally it is preferable that the thickness of this inorganic frit glass layer is not greater than 150 μm. Bonding between the respective layers is accomplished by stacking the layers adjacent each other heat treating the layered structure at a temperature equal to or above the sintering temperature of the bonding frit. One other desirable feature of the frit is that the frit should exhibit a coefficient of thermal expansion that does not significantly differ from that of the parts to be bonded (i.e. +/- 10^"6K^'1). Two acceptable low-expansion frit which can be utilized in this embodiment includes the following; (1) a crystallizing frit that comprises β-eucryptite as the major crystalline species, and, (2) a frit charged with β-eucryptite particles; i.e., a glass frit (glass powder or crushed glass) which has been mixed with ceramic particles resulting in a reduced CTE frit.

[0043] In a second embodiment the bonding layer comprises a metal-alcoxide coating, e.g. a silane coating that is capable of both mechanically and chemically bonding to both the honeycomb structure and the upper and lower glass-ceramic layers. Bonding is again achieved by stacking the layers with the bonding material interposed between the respective layers and subjecting the layered structure to a thermal treatment, preferably to a temperature where organic compounds are burnt out and the metal-alcoxide coating (or bond) transforms into an inorganic layer.

[0044] In a third embodiment, the bonding layer is comprised of a metallic material. One suitable choice for this metallic bond layer includes the use one or more layers comprised of an aluminum-containing alloy. As for the previous bonding layers, bonding is achieved by stacking the layers with the metallic bonding material interposed between the respective layers and subjecting the layered structure to a thermal treatment at a temperature not higher

U than 700 ⁰C so as to oxidize metallic layer such that it forms a hermetic bond with the ceramic and glass-ceramic materials. However, one consideration in utilizing a metallic bond layer is that it is critical to utilize a metallic bond utilized which will not cause contamination of the wafer and/or mask.

[0045] One final bonding layer embodiment involves the use of an organic or hybrid bonding layer including, but not limited to epoxy or adhesive; particularly one that is vacuum and UV-stable can be used.

[0046] The heat treating of the bonding layers, regardless of which of the aforementioned bonding layer alternatives, can be performed by complete heating, for example, in a furnace. However, due to low thermal expansion of the bonding layer localized heating, e.g. heating with a laser beam, may be utilized to accomplish the desired bonding between the bonding layer and the respective top and bottom glass-ceramic layers.

[0047] In order to enhance the bonding of the bonding layer to the bottom or top glass- ceramic layer, all or at least a portion of the honeycomb layer structure channels on either side can be closed/plugged with a cement paste; particular materials which can be used are well known to the skilled in the art. This closing or plugging of channels on either side are likely to the contact area with the top plate (or bottom plate) and thus improve bonding. In addition, heat transfer in the honeycomb structure can be optimized/enhanced through the use of the cement paste.

[0048] Referring again to the inner honeycomb substrate layer, it is preferred that the ceramic honeycomb substrate, regardless of whether cordierite or aluminum titanate is utilized, be preconditioned prior to assembly with/bonding to the bottom and top glass- ceramic layers to form the layered article support embodiment. One means for preconditioning involves the full wetting of the honeycomb substrate with a suitable silane solution and subsequent heat treatment; the result is the production of a layer rich in silicon oxide that will cover both inner and outer surface of the honeycomb. Benefits of this preconditioning and formation of the silicon oxide layer include: (a) an increase in the mechanical stability of the honeycomb due to a covering of the surface defects with the SiO₂- rich layer; and, (b) increased performance of the bond, depending on the particular type of silane solution utilized; (c) a reduction, and in some cases the prevention, of the formation of prevent that individual ceramic particles (from the honeycomb) thereby avoiding the contamination the wafer or mask and, the processing chambers; and (4) increase in the performance or operation of the article support/handling tool in vacuum conditions due to the covering of surface defects, porosity or other cavities with the silicon oxide layer, and the resultant minimization of micro-condensation.

[0049] One final embodiment of the cordierite glass-ceramic article support structure (not show) contemplated by the inventors involves a top glass-ceramic material layer and bonded thereto a bottom layer 16 comprised of a glass-ceramic, ceramic or crystalline material. In this final embodiment, the top layer is comprised of the aforementioned glass-ceramic material that exhibits the aforementioned desirable properties. In one particular embodiment the glass-ceramic material top layer comprises a glass-ceramic material exhibiting cordierite (2MgO.2 Al₂O₃.5SiO₂) as the predominate crystalline phase. As in the previous non-layered and honeycomb embodiment this cordierite glass-ceramic material exhibits a fracture toughness greater than 1.5 MPa/m^1/2, a coefficient of thermal expansion of less than 1.0x10^" ⁶K^"1, a thermal conductivity greater than about 3.5 W/(m.K), an elastic modulus of greater than 120 GPa, a high elastic-to-density ratio in excess of 40 GPa-g/cm³ and a thermal stability coefficient of less than or equal to 0.25. There is no limitation on the thickness of this top cordierite glass ceramic layer, however, as before if the layer is too thick, the weight of the overall layered structure is unacceptable; that said, it is recommended that this top glass- ceramic layer exhibit a thickness of 5 mm or less.

[0050] Both embodiments of the present invention, the simple cordierite glass-ceramic article support embodiment and the layered article support embodiment provide a number of advantages over the conventional support materials, including the following: (1) when compared to conventionally used glass ceramics, such as Zerodur (Schott) or ClearCeram (Ohara), the present article support embodiments are capable of achieving higher thermal conductivity, which in turn enable mores stable temperatures during wafer processing (particularly during immersion lithography) which in turn enables higher resolution during the patterning process. Higher elastic modulus and higher stiffness are also achieved enabling higher geometric stability when moving and, particularly, accelerating at high speeds, again in turn enabling higher geometric precision and a higher overlay stability, or for a given precision requirement, a higher achievable acceleration and thus higher throughput; (2) when compared to conventional cordierite ceramic materials, particularly those derived from sintering a precursor powder, the instant article support embodiments, because of their essentially non-porous characteristics, exhibit a lower density (higher elastic modulus-to- density ratio), a higher thermal conductivity, are capable of exhibiting significantly improved surface quality and are easier to finish;

[0051] In short, the benefits of the either the simple cordierite glass-ceramic article support embodiment and the layered article support embodiment achieves the following (1) a handling tool/article support that enables ultra-high precision positioning of wafers, optical masks, or other components in semiconductor patterning machines; (2) geometrical stability under mechanical and thermal load with minimal requirements for active control; (3) minimization of the contamination of the process chamber coupled with minimization of the resultant abrasion of the particles of top glass-ceramic surface layer, both of which lead to maximization of the lifetime of the article support or tools.

[0052] Referring specifically to the layered or sandwich embodiment, an additional advantage when compared to conventional article supports designs/materials is that this layered structure which incorporates an inner honeycomb material enables the manufacture of much lighter components, which in turn results in higher processing speeds, less vibration and, effectively, higher lithographic resolution.

[0053] Again referring specifically the layered or sandwich embodiment one final advantage of this layered configuration is that it enables flexibility of design and optimization and/or varying of material/ support characteristics; i.e., it enables product designers/engineers more design flexibility in that the key properties/functionality reside in the different portions of the layered configuration . For instance if the particular application required a highly wear resistible top plate with only moderate thermal conductivity, this could be achieved through the use of a thin top plate, while the honeycomb middle layer would be designed so as to allows efficient heat transfer. Alternatively, if the application required a highly conductive top plate, a thicker top plate which itself ensure would ensure quicker heat transfer could be utilized, while a thinner cordierite ceramic middle layer would still provide the necessary stiffness.

[0054] One final advantage contemplated for this layered support embodiment of this design is the ease of manufacturing when compared to manufacturing of article supports comprising bulk glass ceramics such as Zerodur^®. Typically, these conventional bulk glass ceramic article supports require the inclusion of machined-in cooling channels. As such, this necessitates the use of article supports exhibiting a relatively large initial thickness; e.g. the use of (thick) glassy and glass ceramic bodies exceeding 15 mm in thickness. Glass-ceramic 53 structures exhibiting a thickness this large are relatively difficult to manufacture for a number of reasons: (1) compositional homogeneity is difficult to achieve throughout the body; (2) relatively long cooling times are required (sometimes up to several months) so as to alleviate thermal stresses and to achieve thermal homogeneity; (3) excessive long crystallization times due to the same thermal homogeneity and thermal stresses issues; and, (4) in order to achieve these large thickness difficult processing techniques such as casting (vs. conventional rolling) are required. That being said, it follows that production of article supports incorporating comparably thin glass ceramic sheet (e.g. <5 mm) in the layered configuration are preferable and/or desired. Conventional rolling (or roll-pressing) production techniques may be used, reduced crystallization times (with much less risk of fracture due to thermal stresses) are achieved with much less risk of fracture due to thermal stresses. In short, energy consumption during processing, manufacturing costs, processing time and processing defects are all likely to be reduced for the inventive layered article support embodiment. [0055] 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 applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms "wafer" or "die" herein may be considered as synonymous with the more general terms "substrate" or "target portion", respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and/or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

[0056] Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention may be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography. In imprint lithography a topography in a patterning structure defines the pattern created on a substrate. The topography of the patterning structure may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning structure is moved out of the resist leaving a pattern in it after the resist is cured.

[0057] The terms "radiation" and "beam" used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g. having a wavelength of or about 365, 355, 248, 193, 157 or 126 nm) and extreme ultra-violet (EUV) radiation (e.g. having a wavelength in the range of 5-20 nm), as well as particle beams, such as ion beams or electron beams.

[0058] The term "lens", where the context allows, may refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic and electrostatic optical components.

[0059] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g. semiconductor memory, magnetic or optical disk) having such a computer program stored therein.

[0060] The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims

What is claimed is:

1. An article support configured to support an article to be placed in a beam path of a radiation beam of a lithographic apparatus, the article support comprising a glass-ceramic material which exhibits a fracture toughness of greater than 1.5 MPa/ m^1/2, a coefficient of thermal expansion of less than 1.Ox 10 ^"6K^"1 , a thermal conductivity greater than about 3.5 W/(m-K), an elastic modulus of greater than 120 GPa, a high elastic modulus-to-density ratio in excess of 40 GPa-g/cm³ and a thermal stability coefficient < 0.25.

2. The article support according to claim 1, wherein the glass-ceramic material is essentially non-porous.

3. The article support according to claim 1 wherein the glass-ceramic material is a glass- ceramic exhibiting cordierite as the predominate crystalline phase.

4. The article support according to claim 1 wherein article support includes a top layer comprised of the glass-ceramic material, a middle layer comprising a honeycomb ceramic material, and a bottom layer comprised of a thermally conductive, stiff and abrasion resistant glass-ceramic, ceramic or crystalline material.

5. The article support according to claim 4 wherein the bottom layer is comprised of a material selected from the group consisting of cordierite glass-ceramic, sintered cordierite, silicon carbide, silicon nitride, aluminum nitride, aluminum titanate, boron nitride.

6. The article support according to claim 1 wherein the bottom layer is comprised of the same glass-ceramic material as the top layer.

7. The article support according to claim 4, wherein the honeycomb ceramic material comprises either cordierite or aluminum titanate.

8. The article support according to claim 7 wherein the honeycomb material layer is comprised of a single extruded piece.

9. The article support according to claim 7 wherein the honeycomb material is comprised of plurality of segments affixed together.

10. The article support of claim 4, wherein the top and bottom glass-ceramic material layers are bonded to the middle honeycomb ceramic material layer via a bonding layer.

1 1. The article support of claim 10 wherein the bonding layer is comprised of material selected from the group consisting of a low temperature inorganic glass frit, a silane material, a metallic layer or a vacuum, UV stable organic material.

12. An article support configured to support an article to be placed in a beam path of a radiation beam of a lithographic apparatus, the article support comprising a stiff, thermally conductive top glass-ceramic material layer exhibiting a high fracture toughness, a low coefficient of thermal expansion and a low thermal stability coefficient, and a middle layer comprising a honeycomb ceramic material, and a bottom layer comprising either a glass- ceramic, ceramic or crystalline material.

13. The article support of claim 12 where the top glass-ceramic layer comprised a glass - ceramic which exhibits a fracture toughness of greater than 1.5 MPa/m^1/2, a coefficient of thermal expansion of less than LOxIO^-6K^'1, a thermal conductivity greater than about 3.5 W/(m-K) an elastic modulus of greater than 120 GPa, a high elastic modulus-to-density ratio in excess of 40 GPa-g/cm³ and a thermal stability coefficient < 0.25.

14. The article support of claim 13 wherein the glass-ceramic material is a glass-ceramic which exhibits cordierite as the predominate crystalline phase.

15. The article support according to claim 12, wherein the honeycomb ceramic material comprises either cordierite or aluminum titanate.

16. The article support according to claim 12 wherein the honeycomb material layer is comprised of a single extruded piece.

17. The article support according to claim 12 wherein the honeycomb material is comprised of plurality of segments affixed together.

18. The article support of claim 12, wherein the top and the bottom material layers are bonded to the middle honeycomb ceramic material via a bonding layer.

19. The article support of claim 18 wherein the bonding layer is comprised of material selected from the group consisting of a low temperature inorganic glass frit, a silane material, a metallic layer or a vacuum, UV stable organic material.