Method for optimizing a characteristic curve in a solid substrate precursor

Abstract

The present invention relates to a method for optimizing a property profile in a solid substrate precursor. In particular, the present invention relates to a method for preparing a substrate precursor comprising a TiO2-SiO2 hybrid glass having a mass of more than 100 kg.

Description

Background Technology

[0001] The present invention relates to a method for preparing a substrate precursor containing a TiO2-SiO2 mixed glass with a mass greater than 50 kg, particularly greater than 100 kg.

[0002] Existing technology

[0003] EP2960219A1 describes the generation of highly integrated structures with linewidths less than 50 nm using microlithography projection equipment in EUV lithography. Typically, working radiation from the spectral range between 10 nm and 121 nm is used, which is referred to as the EUV range (extreme ultraviolet light, also known as "soft X-ray radiation").

[0004] The projection device is equipped with a mirror element, which is essentially composed of synthetic high-silica quartz glass doped with titanium dioxide (hereinafter also referred to as "TiO2-SiO2 hybrid glass" or "TiO2-SiO2 glass"), and incorporates a reflective layer system. The TiO2-SiO2 hybrid glass is characterized by an extremely low coefficient of thermal expansion (hereinafter also referred to as "CTE"). CTE is a glass property that depends on the glass's thermal history and several other parameters, but primarily on the titanium dioxide concentration.

[0005] The substrate precursor of TiO2-SiO2 mixed glass is mechanically processed to form a mirror substrate, and then mirrored to form a mirror element.

[0006] The increasing demands for linewidth have led to higher requirements for TiO2-SiO2 hybrid glasses. To achieve smaller linewidths, EUV source power is often increased. This increase in EUV power primarily results in higher throughput for the stepper and also leads to greater heating of the mirror. Therefore, a more uniform and sharper mirror is needed, as imaging errors otherwise increase with source power.

[0007] Furthermore, a smaller structural width itself necessitates better imaging characteristics. In this case, numerical aperture is particularly important. The optical aperture angle of a mirror objective is directly related to optical resolution. A higher numerical aperture (i.e., a higher beam angle) allows for better resolution. However, this requires a larger mirror substrate.

[0008] Due to production-related reasons, TiO2-SiO2 hybrid glasses include a microlayer structure. JP2006240979A describes a method for reducing this layer structure. It has been found that, unfavorably, in the production of substrate precursors with a desired mass greater than 100 kg, in addition to the micro-production-related layer structure, macro-production-related titanium profiles also appear. These production-related titanium profiles affect the quality of the final substrate precursor and cannot be eliminated by known methods.

[0009] Technical goals

[0010] Generally speaking, the object of this invention is to at least partially overcome the disadvantages arising from the prior art. Another object of this invention is to provide a substrate precursor in which the influence of macroscopic production-related titanium profiles is reduced. A further object of this invention is to provide a substrate precursor in which the influence of macroscopic production-related characteristic profiles is reduced. A further object of this invention is to provide a substrate precursor with a mass greater than 50 kg, particularly greater than 100 kg, through which high numerical apertures are achieved.

[0011] Preferred embodiments of the present invention

[0012] The features of the independent claim contribute to at least partially satisfying at least one of the foregoing objectives. The dependent claims provide preferred embodiments that contribute to at least partially satisfying at least one of these objectives.

[0013] |1.| A method for preparing a substrate precursor (900) containing a TiO2-SiO2 mixed glass with a mass greater than 50 kg, comprising the following steps:

[0014] • Introduce silica raw materials and titanium dioxide raw materials (1000) into the flame (225),

[0015] • Prepare a glass body (300) with a titanium dioxide content of 3% to a maximum of 10% by weight (1100), said glass body (300) comprising:

[0016] • Macroscopic production-related titanium curves (410, 410', 410”, 410”'), and

[0017] • Microscopic production-related layer structure,

[0018] • The glass body is divided (1200) into multiple rod-shaped glass body portions (400, 400', 400”, 400”').

[0019] • Spatial measurement (1300) of the titanium curve (410, 410', 410”, 410”') in each of the vitreous portions (400, 400', 400”'),

[0020] • Connect the glass portions (400, 400', 400”, 400”') of (1500) to form an elongated first glass component (600).

[0021] • The first homogenization treatment (1600) of the first glass component (600),

[0022] • Push the first glass components (600) together (1700) to create a spherical glass system (700).

[0023] • Rotate (1800) the glass system (700) by more than 70 degrees.

[0024] • Stretch (1900) the glass system (700) to form an elongated second glass component (800),

[0025] • The second homogenization process (2000) of the second glass component (800) produces a substrate precursor that is substantially free of layer structures.

[0026] Its features are,

[0027] The measurement process includes the following steps:

[0028] • The desired spatial titanium distribution (420) in the substrate precursor is determined in advance (1400).

[0029] • Provides a model for titanium allocation (430) in the substrate precursor (1420), the model depending on

[0030] The arrangement of the plurality of glass portions (400, 400', 400”, 400”') in the first glass component (600) relative to each other.

[0031] • The spatial titanium curves (410, 410', 410”, 410”') in each of the glass portions (400, 400', 400”'), and

[0032] • The effects of the pushing together (1700) and the rotating (1800) steps on the spatial titanium curve (410, 410', 410”, 410”') in the glass body portion.

[0033] • The optimal arrangement of the glass portions (400, 400', 400”, 400”') relative to each other is calculated using the model (1450) to minimize the difference between the titanium distribution (430) and the titanium distribution (420).

[0034] • Position (1470) the vitreous portion (400, 400', 400”, 400”') such that, in the step of connection (1500), the vitreous portion (400, 400', 400”') is positioned such that, during the connection step (1500), the vitreous portion (400, 400’, 400”') is positioned such that, during the connection step (1500), the vitreous portion (400, 400’, 400”') is positioned such that, during the connection step (1500), the vitreous portion (400, 400” ...

[0035] The 400”, 400”’) are connected according to the calculated optimal arrangement.

[0036] |2.|The method according to embodiment 1 is characterized in that the substrate precursor has a greater than

[0037] 100kg, especially more than 200kg, especially more than 300kg.

[0038] |3.| The method according to at least one of embodiments 1 or 2, characterized in that, the

[0039] The method includes the following steps:

[0040] • Prepare a second glassy body with a titanium dioxide content of 3% to a maximum of 10% by weight.

[0041] The second vitreous body comprises:

[0042] • The second macroscopic production-related titanium curve, and

[0043] • The second microscopic layer structure related to production.

[0044] • Divide the second glass body into multiple rod-shaped glass body segments.

[0045] |4.| The method according to at least one of the foregoing embodiments is characterized in that at least

[0046] Three, particularly at least five, particularly at least eight glass portions are connected to form the first glass component.

[0047] |5.| The method according to at least one of the foregoing embodiments, characterized in that it is based on titanium

[0048] The maximum value of the distribution (420), the difference between the titanium distribution (430) and the titanium distribution (420) is less than 1.5%, particularly less than 1.0%, particularly less than 0.5%.

[0049] |6.| The method according to at least one of the foregoing embodiments, characterized in that, the

[0050] The vitreous humor includes at least one of the following characteristic curves:

[0051] • Macroscopic production-related OH curves

[0052] • Macro-level production-related CTE curves

[0053] • Macroscopic production-related fluorine curves

[0054] • Macro-level production-related bubble curves

[0055] • Macro-level production-related ODC curves

[0056] • Macroscopic Ti3+ curves related to production

[0057] • Macroscopic production-related metal impurity curves.

[0058] |7.| The method according to embodiment 6 is characterized in that, in the measurement step,

[0059] At least one of the characteristic curves is measured in each of the glassy portions.

[0060] |8.| The method according to embodiment 7 is characterized in that the measurement step includes using

[0061] Next steps:

[0062] • Predetermine the desired spatial characteristic distribution in the substrate precursor.

[0063] • Provide a model for the property allocation in the substrate precursor, the model depending on

[0064] • The arrangement of the plurality of glass portions in the first glass component relative to each other,

[0065] • The spatial characteristic curve of each glass segment in the glass segment, and

[0066] • The effect of the pushing and rotating steps on the spatial characteristic curve in the vitreous portion.

[0067] • The optimal possible arrangement of the vitreous portions relative to each other is calculated using the model, such that the sum and difference are minimized, the sum and difference including

[0068] The difference between titanium allocation and titanium distribution, and

[0069] • The second difference between the characteristic assignment and the characteristic distribution,

[0070] • Position the glass portion such that, during the connection step, the glass portion is connected according to the calculated best possible arrangement.

[0071] |9.|The method according to embodiment 8 is characterized in that the sum of the maximum value of the titanium distribution (420) and the maximum value of the characteristic distribution is less than 1.5%, particularly less than 1.0%, particularly less than 0.5%.

[0072] |10.| The method according to at least one of the foregoing embodiments is characterized in that the step of preparing the glass body includes at least the following steps:

[0073] • A porous soot body is produced, wherein the macroscopic production-related titanium profile extends substantially along the longitudinal axis, and the microscopic process-related layer structure extends substantially along the growth axis.

[0074] • Vitrify the soot to produce a cylindrical glass body.

[0075] |11.|The method according to at least one of the foregoing embodiments, characterized in that the first glass component is heated prior to the step of pushing them together.

[0076] |12.|The method according to at least one of the foregoing embodiments, characterized in that the connection occurs at the relevant contact surface of the glass portion.

[0077] In this specification, the range specification also includes values ​​designated as limits. Therefore, the specification "within the range of X to Y" relative to the type of variable A means that A can assume values ​​X, Y, and values ​​between X and Y. Therefore, the range "at most Y" defined on one side of the type of variable A means as the value Y and less than Y.

[0078] Some of the characteristics described are related to the term "substantially". The term "substantially" should be understood to mean that, under actual conditions and manufacturing techniques, the precise mathematical interpretation of terms such as "overlapping", "perpendicular", "diameter", or "parallelism" may never be given precisely, but can only be applied within certain manufacturing-related error tolerances. In particular, the term "substantially" can mean a variation of + / -5% in a relevant value. Specifically, "substantially parallel axes" includes angles between each other from -5 degrees to 5 degrees, and "substantially equal volumes" includes a deviation of at most 5% by volume. "A device substantially composed of quartz glass" includes, for example, a quartz glass content of ≥95% by weight to ≤100% by weight. Furthermore, "substantially right-angled" includes angles from 85 degrees to 95 degrees. Detailed Implementation

[0079] This invention relates to a method for preparing a substrate precursor containing a TiO2-SiO2 mixed glass with a mass greater than 50 kg, the method comprising the following steps:

[0080] • Introduce silica and titanium dioxide raw materials into the flame.

[0081] • Prepare a glassy substance with a titanium dioxide content of 3% to a maximum of 10% by weight, the glassy substance comprising:

[0082] ο Macroscopic production-related titanium curves, and

[0083] ο Microscopic production-related layer structure,

[0084] • Divide the vitreous body into multiple rod-shaped vitreous segments.

[0085] • Spatial measurement of the titanium profile in each glass segment of the vitreous body.

[0086] • Connect the glass portions to form an elongated first glass component.

[0087] • First homogenization treatment of the first glass component

[0088] • Push the first glass components together to create a spherical glass system.

[0089] • The rotating glass system can rotate more than 70 degrees.

[0090] • A stretching glass system is used to form an elongated second glass component.

[0091] • A second homogenization process is performed on the second glass component to produce a substrate precursor that is substantially free of layer structures.

[0092] To overcome the aforementioned drawbacks of the prior art, according to the present invention, the measurement steps include the following steps:

[0093] • Predetermine the desired spatial titanium distribution in the substrate precursor.

[0094] • Provide a model for titanium allocation in the substrate precursor, which depends on

[0095] The arrangement of multiple glass sections in the first glass component relative to each other.

[0096] The spatial titanium curve in each glass segment of the vitreous body, and

[0097] The effects of pushing together and rotating together on the spatial titanium curve in the glass body section.

[0098] • The optimal arrangement of the glass components relative to each other is calculated using a model to minimize the difference between the titanium distribution and the titanium allocation.

[0099] • Position the glass portion so that, during the connection step, the glass portion is connected according to the calculated optimal arrangement.

[0100] The scope of the method relates to optimizing the spatial distribution of titanium dioxide, particularly titanium dioxide and at least one other property, in a substrate precursor. For linguistic reasons, the terms "titanium" and "titanium dioxide" are used synonymously below. In fact, this invention and specification do not refer to the element titanium, but rather to its oxide form, titanium dioxide. Furthermore, the following words and suffixes are used to describe the spatial distribution of titanium dioxide and / or at least one other physical or chemical property at different stages of the method:

[0101] • In the vitreous body and within its components, the term "curve" refers to...

[0102] • In substrate precursors, the term "frequency"

[0103] In the model, the word "allocation," and

[0104] • In the desired substrate precursor, the term "distribution".

[0105] In this regard, by example, the difference between the titanium curve and the titanium frequency is as follows:

[0106] The first term represents the titanium dioxide content at different points within the vitreous body, and...

[0107] • The second refers to the titanium dioxide content at different points in the bulk space in front of the substrate.

[0108] This method enables the fabrication of substrate precursors weighing greater than 50 kg, particularly greater than 100 kg, which meets the growing demand for EUV mirror devices. In this case, the method includes the following steps:

[0109] Introduction

[0110] In the introductory step, silica raw materials (e.g., SiCl4 or OMCTS vapor) and titanium dioxide raw materials (e.g., TiCl4 or Ti alkoxide vapor) are subjected to flame hydrolysis. During this process, SiO2 and TiO2 particles are formed.

[0111] preparation

[0112] SiO2 and TiO2 particles formed within the flame hydrolysis range can be deposited in two ways. In direct deposition (DQ process), deposition occurs on a mold located below the flame. Typically, temperature conditions are selected to allow this deposition to occur, resulting in a dense TiO2-SiO2 mixed glass. In axial vapor deposition (VAD process), deposition occurs on a support rod in the form of a film of SiO2 and TiO2 particles. Subsequently, in a second step, the particles are vitrified to form a TiO2-SiO2 mixed glass.

[0113] The result of this step is a glassy body with a titanium dioxide content of 3 to 10 wt% TiO2, which includes a microscopic production-related layered structure, also known as a short-wavelength layered structure, which is produced by the layered deposition of SiO2 and TiO2 particles.

[0114] The mass specified here and below always refers to the amount of TiO2 (titanium dioxide), not elemental titanium.

[0115] Due to fluctuations in the mass flow controller (MFC), mechanical inaccuracies in the burner or the burner and deposition system retainer, or randomly and / or deterministically varying thermal boundary conditions during construction, glass bodies with a self-weight greater than 50 kg, particularly greater than 100 kg, particularly greater than 200 kg, include macroscopic production-related titanium profiles in addition to the aforementioned microscopic production-related layer structures. The short-wavelength layer structures have dimensions less than 1 mm, particularly less than 0.5 mm.

[0116] The macroscopic titanium profile (also known as long-wave fluctuation or long-wave titanium profile) has a specific fluctuation length of 0.15 m to 0.75 m, particularly 0.17 m to 0.5 m, wherein the titanium dioxide content fluctuates by a maximum of 0.5 wt%, particularly a maximum of 0.3 wt%, particularly between 0.02 wt% and 0.25 wt%, particularly between 0.05 wt% and 0.2 wt%. In an exemplary vitreous body having a length of one meter and a titanium dioxide content of 10 wt% and a macroscopic production-related fluctuation of + / - 0.5 wt%, the titanium dioxide content can therefore spatially fluctuate between 10.5 wt% and 9.5 wt%, particularly several times.

[0117] segmentation

[0118] The glass produced in the preparation step can have a cylindrical, rod-shaped, or tubular shape. The glass is divided into multiple rod-shaped glass segments along a predefined longitudinal axis.

[0119] Measurement

[0120] In the measurement step, the titanium dioxide content is measured at multiple spatially different points. For example, a separate titanium profile is determined for each glassy portion produced in the segmentation step. For this purpose, the content and / or properties of titanium dioxide are measured along the longitudinal axis of the glassy portion. In this case, the distance between the measurement points is less than 5 cm, and particularly less than 2 cm. The measurement accuracy in determining the titanium dioxide content is 0.005% by weight.

[0121] connect

[0122] Multiple glass components are joined together in a joining step to form an elongated first glass member. In this case, the joining can be carried out, in particular, as an integral bonding process within the scope of a thermal process. The term "thermal process" is understood as a method step in which the temperature of the component is increased by heat input. Examples of thermal processes:

[0123] - Flame-based thermal processes are based on the oxidation of exothermic reactive gases. One example is using hydrogen (also known as "H2") as a fuel gas (flame hydrolysis). It reacts with oxygen (also known as "O2") in the air.

[0124] Flameless heating processes use other heating systems that do not require an open flame. One example is the use of resistors that convert electrical energy into heat.

[0125] First homogenization process

[0126] In the first homogenization process, during crucible-free melting, the short-wavelength microstructure of the first glass component is eliminated in a plane. For this purpose, the first glass component can be clamped in the chuck of a glass lathe and softened in a zoned manner, while the chuck rotates at different speeds or in opposite directions around the axis of rotation. Due to the different rotations of the first glass component on either side of the softening zone, twisting (torsion) occurs in the glass volume, resulting in mechanical mixing. The thermo-mechanically mixed region is also referred to as the "shear zone." The shear zone has a length of 2 cm to 8 cm, which is more than an order of magnitude longer than the length of short-wavelength layer structures with a length of less than 1 mm. The shear zone is displaced along the longitudinal axis of the first glass component and mixed along its length in the process. Thus, the microscopic production-related layer structure is reduced or eliminated in a plane (specifically, the plane of the shear zone).

[0127] When the homogenized TiO2-SiO2 hybrid glass is examined using a voltage detector and interferometer, it is found that the optical layer structure degrees of freedom parallel to the shear zone plane used during homogenization are lower than those observed perpendicular to the shear zone plane. This indicates that the mixing effect used in the shear zone to achieve the layer structure degrees of freedom is less in the direction perpendicular to the rotation axis used during homogenization than the mixing effect observed along the rotation axis.

[0128] Pushing together

[0129] After the first homogenization process, the first glass components are heated and mechanically pushed together. By pushing the two ends together along the longitudinal axis of the first glass components, a spherical glass system is produced.

[0130] Rotation

[0131] The spherical glass system is rotated more than 70 degrees relative to the longitudinal axis of the first glass component. The rotation angle can be particularly between 70 and 110 degrees, and particularly between 80 and 100 degrees.

[0132] stretching

[0133] After rotation, the glass system is heated to allow for longitudinal stretching. This enables the spherical glass system to be reformed into slender, particularly rod-shaped, second glass components.

[0134] Second homogenization process

[0135] To eliminate remaining microscopic production-related layer structures, a second homogenization process is performed on the second glass component. This second homogenization process is similar to the first. For this purpose, the second glass component can be clamped in the chuck of a glass lathe and softened in a zoned manner, while the chuck rotates at different speeds or in opposite directions around the axis of rotation. Due to the different rotations of the second glass component on either side of the softening zone, twisting (torsion) and thus mechanical mixing occur again within the glass volume. The shear zone shifts along a second length of the second glass component, and in this process, the latter is reshaped and mixed along its length. Therefore, microscopic production-related layer structures are reduced or eliminated in a plane (specifically, the plane of the shear zone).

[0136] If TiO2-SiO2 mixed glass that has undergone two homogenization treatments is examined by voltage detector and interferometer, it is found that the micro-production-related layer structure has been substantially removed, especially at least 99% compared to the glass body.

[0137] As a result of the second homogenization process for the second glass component, a substrate precursor that is substantially free of microscopic production-related layer structures was produced.

[0138] In one embodiment, the first glass component and / or the second glass component are clamped in a rotating device with the longitudinal axis horizontally oriented, and retaining elements are possible to minimize the loss of good material to be welded to the ends of the first glass component and / or the second glass component.

[0139] Measurement according to the present invention:

[0140] To overcome the aforementioned drawbacks of the prior art, the measurement procedure is specified to include the following steps:

[0141] • Predetermine the desired spatial titanium distribution in the substrate precursor.

[0142] • Provide a model for titanium allocation in the substrate precursor, which depends on

[0143] The arrangement of multiple glass sections in the first glass component relative to each other.

[0144] The spatial titanium curve in each glass segment of the vitreous body, and

[0145] The effects of pushing together and rotating together on the spatial titanium curve in the glass body section.

[0146] • The optimal arrangement of the glass components relative to each other is calculated using a model to minimize the difference between the titanium distribution and the titanium allocation.

[0147] • Position the glass portion so that, during the connection step, the glass portion is connected according to the calculated optimal arrangement.

[0148] Within the range of calculating the optimal arrangement, the positions of the glass components relative to each other are arranged. For each arrangement, the model calculates the titanium distribution, which is then compared to the titanium distribution via difference formation. Based on this set of differences, the optimal arrangement of the glass components relative to each other can then be determined, in which the difference between the titanium distribution and the titanium distribution, particularly the spatial difference, is minimized.

[0149] Predetermined

[0150] Within a predetermined range of steps, the optimal spatial distribution of titanium dioxide in the SiO2 matrix is ​​determined. This titanium distribution is a target value for the spatial distribution of titanium in the substrate precursor and should be optimally achieved during production.

[0151] Titanium allocation includes the absolute amount of titanium dioxide in the substrate precursor and its spatial distribution. For example, the substrate precursor may have a cubic shape. In this case, the titanium allocation may be parabolic, with the maximum value of the titanium allocation located at the center of the surface of the substrate precursor. Furthermore, different edge regions of the substrate precursor may have the same or different titanium allocations. In another embodiment, the titanium allocation may be flat, i.e., uniformly distributed over the entire substrate precursor.

[0152] supply

[0153] The method according to the invention includes a model of titanium distribution in a substrate precursor. This model calculates the spatial distribution of titanium dioxide in a SiO2 matrix. In this case, the following are used as input parameters for the model:

[0154] A / Arrangement of multiple glass portions relative to each other in the first glass component.

[0155] B / Individual spatial titanium curves in multiple glassy sections, and

[0156] The effects of the push-to-pull and rotation steps on the spatial titanium curve in the glassy section.

[0157] When calculating the spatial distribution of titanium dioxide in the SiO2 matrix based on the aforementioned input parameters, the model can take other aspects into account.

[0158] In the fabrication of the glass body, long-wavelength and short-wavelength fluctuations occur in the amount and / or other properties of titanium in the SiO2 matrix. These two types are affected differently in the method steps according to the method disclosed herein. Using this model, in the joining step, the titanium distribution of various arrangements of the glass body portion can be calculated and compared with target values. Therefore, a large substrate precursor of the desired quality can be achieved, and waste can be reduced.

[0159] The starting point is that both the first and second homogenization treatments only affect changes in the short-wavelength (microscopic) layer structure and / or short-wavelength (microscopic) titanium dioxide content. In contrast, long-wavelength variations in titanium dioxide content remain unaffected by either homogenization treatment. This fact is due to the different length scales of the shear zone and the macroscopic production-related titanium profile. The shear zone has a slender extension of only a few centimeters. Within this shear zone, only the short-wavelength structure located in the plane of the shear zone is compensated.

[0160] The long-wavelength variation of titanium dioxide content is unaffected by the two homogenization treatments. This is because the fluctuation length of the long-wavelength variation of titanium dioxide content and / or properties is at least twice the width of the shear zone.

[0161] The rotation step does not affect the short-wave (micro) layer structure and / or the short-wave (micro) titanium dioxide content. However, the rotation step ensures that the shear zones of the first and second homogenization treatments are arranged substantially perpendicular to each other relative to the longitudinal axis of the first glass component. Therefore, the short-wave fluctuations should be flattened as completely as possible.

[0162] The rotational step affects long-wavelength fluctuations. By pushing the first glass components together in the pushing step, different long-wavelength fluctuations from different glass sections are mixed with each other. The volumetric elements of the removed first glass components are brought into direct contact through this process and can be combined in subsequent steps. Therefore, in particular, the amplification or attenuation of the fluctuation level of long-wavelength fluctuations can be achieved according to the titanium curve and / or characteristic curve. Thus, the amplification or attenuation of the fluctuation level depends on the titanium curve and / or characteristic curve and on the arrangement of the individual glass sections relative to each other.

[0163] Finally, the glassy portions again lie in different planes of the substrate precursor. The number of planes depends on the mass of the substrate precursor and the number and mass of the glassy portions. In one variation,

[0164] For substrate precursors with a mass greater than 50 kg, the number of planes can be between 2 and 5.

[0165] For substrate precursors with a mass greater than 100 kg, the number of planes can be between 3 and 10.

[0166] For substrate precursors with a mass greater than 200 kg, the number of planes can be between 5 and 20.

[0167] • For substrate precursors with a mass greater than 300 kg, the number of planes can be between 10 and 30.

[0168] The exception to the statement that the rotation step affects long-wavelength fluctuations applies to macroscopic quartz glass volumetric elements arranged at the center of an elongated first glass component and specifically having dimensions between 20 cm³ and 100 cm³. Long-wavelength variations in properties, such as the amount of titanium in the SiO₂ matrix, are also observed in this macroscopic volumetric element. The rotation step merely changes the position of this volumetric element in such a way that it is once again located at the center of the spherical glass system. During the subsequent stretching, this volumetric element is again arranged at the center of an elongated second glass component. Thus, the volumetric element, with its long-wavelength fluctuations unaffected by homogenization, is once again centrally located in the second glass component.

[0169] In another embodiment, the second homogenization step is followed by a flow-out into a graphite mold. After the flow-out step, the described quartz glass element is located at the center of the substrate precursor and thus substantially determines its behavior. This is more applicable because a raised groove is typically milled into the substrate precursor, which receives the actual mirror surface, and the volumetric element located directly beneath the groove thus greatly influences the behavior of the mirror surface during use.

[0170] Therefore, the model can consider at least one of the following options in order to search for the optimal option, wherein the following options are minimized and / or optimal:

[0171] D / The titanium dioxide content in the functional region, especially in the central volume element of the substrate precursor, and

[0172] E / Titanium dioxide content in different planes of the substrate precursor.

[0173] The model calculates the spatial distribution of titanium dioxide in the SiO2 matrix of the substrate precursor that may be potentially generated during the method steps, depending on at least three listed input parameters A / to C / . This leads to

[0174] • Different arrangements of multiple glass portions relative to each other in the first glass component, and / or

[0175] • Select multiple glass portions from a large number of glass portions and combine them with the different arrangements of multiple glass portions in the first glass component relative to each other.

[0176] calculate

[0177] The probability of titanium distribution in the substrate precursor, calculated using a model based on the arrangement of the glass portions relative to each other, is compared with the desired titanium distribution in the substrate precursor. Since the titanium distribution represents the desired target value, an arrangement of multiple glass portions with the smallest difference between the titanium distribution and the desired titanium distribution is selected.

[0178] As explained, the titanium curve is determined at points in the spatial measurement step. In one variation, the model determines only a set of points, rather than the complete curve of the titanium distribution. According to the invention, in each case, the difference between each possible arrangement of the glass portion is calculated.

[0179] In one implementation, the difference between the sequences is determined using the root mean square (RMS). The model then examines which of all possible arrangements of the vitreous portions results in the minimum difference, i.e., the smallest difference. The arrangement of the vitreous portions with the smallest difference between the calculated titanium distribution and the titanium allocation is then used in the connection step.

[0180] In one implementation, the difference between the sequences is determined by summing the magnitudes of their differences.

[0181] In one implementation, the difference between the sequences is determined by the arithmetic mean.

[0182] In one implementation, the minimum difference is understood to mean that the difference between the size of the titanium distribution and the size of the titanium distribution is less than 1.5% of the maximum value of the titanium distribution, particularly less than 1.0%, and particularly less than 0.5%. Therefore, the specified size of the difference is a relative value based on the maximum value of the titanium distribution.

[0183] In one embodiment, to determine the difference, at least 75%, particularly more than 85%, particularly at least 90%, of the surface of the substrate precursor is considered.

[0184] In one embodiment, to determine the difference, consideration is given to at least 75%, particularly more than 85%, particularly at least 90%, of the surface of the substrate precursor, which is mirrored in a further step to form a mirror element.

[0185] position

[0186] Subsequently, in the joining step, the desired substrate precursor is achieved by joining the glass portions according to the calculated optimal arrangement.

[0187] One embodiment is characterized by a substrate precursor having a mass greater than 200 kg, particularly greater than 300 kg. Within the scope of the OVD or DQ method, based on the desired titanium dioxide content within 200 kg of TiO2-SiO2 mixed glass, the macroscopic production-related titanium profile can be a spatial variation of at most 0.5% in titanium dioxide content. This spatial variation in titanium dioxide content typically exhibits a continuous curve with fluctuation lengths between 10 cm and 50 cm. In contrast, the shearing zone and the second shearing zone have lengths ranging from 2 cm to 8 cm, wherein the TiO2-SiO2 mixed glass is mixed within the range of two homogenization treatments.

[0188] For substrate precursors with a mass greater than 100 kg, particularly greater than 200 kg, and especially greater than 300 kg, the length of the first glass component is greater than 2 m, particularly greater than 2.8 m. Therefore, several macroscopic production-related fluctuations may occur in the titanium profile, which would have no effect on smaller substrate precursors with a mass less than 30 kg. One embodiment is characterized by the following steps after the second homogenization treatment:

[0189] • The second glass component is reshaped by softening and flowing into a heated mold to form a substrate precursor, the second glass component flowing into the heated mold under force.

[0190] In one embodiment, the outflow step can be specifically used to transform the rod-shaped TiO2-SiO2 mixed glass in the second glass component into a bulk substrate precursor. For this purpose, the mold can have a bulk interior into which the TiO2-SiO2 mixed glass of the second glass component flows out. In particular, the mold can have an interior corresponding to a desired profile and geometry of the desired mirror finish, and the substrate precursor does not require any significant reprocessing (referred to as "near-net shape").

[0191] Within the flow-out step, the second glass component can be placed in a heated mold and can flow out of it under its own weight or under an additional force acting in the axial direction. The same deformation can also be achieved instead of slow flow out of the heated mold, since the second glass component is continuously fed into the heated zone, where the mold arranged in the heated zone softens along its length.

[0192] One implementation method is characterized by comprising the following steps:

[0193] • Prepare a second glassy body with a titanium dioxide content of 3% to a maximum of 10% by weight, the second glassy body comprising:

[0194] • The second macroscopic production-related titanium curve, and

[0195] • The second microscopic layer structure related to production.

[0196] • Divide the vitreous body into multiple rod-shaped vitreous parts.

[0197] To prepare a substrate precursor with a mass greater than 100 kg, especially greater than 200 kg, and especially greater than 300 kg, it may be necessary to prepare not only a first glass body but also a second glass body.

[0198] In this case, the first and second glass bodies have different macroscopic production-related titanium profiles. After the preparation steps, the first glass body is divided into multiple rod-shaped glass body segments, and the second glass body is also divided into multiple rod-shaped glass body segments.

[0199] In one embodiment, all the plurality of rod-shaped glass portions produced by the first glass body and all the plurality of rod-shaped glass portions produced by the second glass body are joined together to form a first glass component.

[0200] In one implementation, the multiple vitreous portions are generated by the sum of the following:

[0201] • Multiple rod-shaped glass segments generated from the first glass body, and

[0202] • Multiple rod-shaped vitreous portions generated by the second vitreous body,

[0203] The plurality of glass portions are larger than the plurality of rod-shaped glass portions required to produce the first glass component. In this case, the desired plurality of glass portions are selected from the plurality of available glass portions within the scope of the calculation steps, such that the difference between the titanium allocation and the titanium distribution is minimized.

[0204] In one implementation scheme

[0205] Specifically, the multiplicity of the vitreous portion is 1.1 to 2 times that of multiple vitreous portions.

[0206] Specifically, the number of glass portions is at least twenty, and the number of glass portions joined together to form the first glass component is at most fifteen.

[0207] • The number of glass portions is at least fifteen, and the number of glass portions joined together to form the first glass component is at most ten.

[0208] The disclosed method allows for the selection of options to overcome the aforementioned drawbacks of the prior art.

[0209] One embodiment is characterized in that at least three, particularly at least five, particularly at least eight glass portions are connected to form a first glass component.

[0210] For substrate precursors with a mass greater than 100 kg, multiple glass sections connected to each other are required. Due to the spatial variation in titanium dioxide content, with a fluctuating length between 10 cm and 50 cm, the method according to the invention is particularly suitable for combinations of more than three, especially more than five, and especially more than eight glass sections, in order to produce substrate precursors that meet the stringent requirements of EUV microlithography.

[0211] One implementation is characterized in that, based on the maximum value of the titanium distribution, the difference between the titanium allocation and the titanium distribution is less than 1.5%, particularly less than 1.0%, and particularly less than 0.5%.

[0212] Within the scope of the measurement steps, the minimum difference between the titanium distribution and the desired titanium distribution is determined by comparing the model with the expected titanium distribution. Due to the increasing demands on the material properties of the substrate precursor, the absolute value of this difference can be subject to the aforementioned limitations.

[0213] One embodiment is characterized in that the vitreous body includes at least one of the following characteristic curves:

[0214] • Macroscopic production-related OH curves

[0215] • Macro-level production-related CTE curves

[0216] • Macroscopic production-related fluorine curves

[0217] • Macro-level production-related bubble curves

[0218] • Macro-level production-related ODC curves

[0219] • Macroscopic Ti3+ curves related to production

[0220] • Macroscopic production-related metal impurity curves.

[0221] With regard to the OVD or DQ methods, macroscopic production-related variations of the properties listed above may occur. The fluctuation lengths that occur in this case are comparable to those of titanium dioxide, and specifically between 12.5 cm and 50 cm for OH, CTE, and Ti3+, and between 15 cm and 85 cm for fluorine, bubbles, ODC, and metallic impurities.

[0222] One embodiment is characterized in that, in the measurement step, at least one characteristic curve is measured in each of the characteristic curves in the vitreous portion.

[0223] One implementation scheme is characterized in that the measurement steps include the following steps:

[0224] • Predetermine the desired spatial property distribution in the substrate precursor.

[0225] • Provides a model for the property allocation in the substrate precursor, which depends on

[0226] • The arrangement of multiple glass sections in the first glass component relative to each other.

[0227] • Spatial characteristic curves of each vitreous segment, and

[0228] • The effects of pushing and rotating steps on the spatial characteristic curves within the vitreous body.

[0229] • Calculate the optimal possible arrangement of the vitreous parts relative to each other using a model, minimizing the sum and difference, which includes...

[0230] The difference between titanium allocation and titanium distribution, and

[0231] The difference between characteristic assignment and characteristic distribution.

[0232] • Position the glass portion so that, during the connection step, the glass portion is connected according to the calculated best possible arrangement.

[0233] In parallel with the step of pre-determining the titanium distribution, in this variation, at least one desired spatial characteristic distribution in the substrate precursor is pre-determined. Therefore, in addition to the titanium distribution, at least one characteristic distribution represents a second target value that is optimally achieved and / or sought in the substrate precursor.

[0234] In one variation, the sum and difference can be calculated from the sum of the following items:

[0235] The magnitude of the difference between titanium allocation and titanium distribution, and

[0236] • The magnitude of the difference between characteristic assignment and characteristic distribution.

[0237] Similar to the titanium curve, the characteristic curve is also measured at points. The model then calculates the value of the characteristic in the substrate precursor (characteristic assignment) from a set of characteristic values ​​in each case. Therefore, for each possible arrangement of the glass portion, the model can calculate the difference between the characteristic assignment and the characteristic distribution from that set of values.

[0238] Based on this, for each possible arrangement of the vitreous portion, the model can determine two independent differences, namely...

[0239] The difference between titanium allocation and titanium distribution, and

[0240] • The difference between characteristic assignment and characteristic distribution.

[0241] In one implementation, each of the two differences is determined by the root mean square (RMS). In another implementation, each of the two differences is determined by the arithmetic mean.

[0242] The model then forms a sum and difference for each possible permutation. In this case, the two differences to be considered can be added to each other in different ways.

[0243] Therefore, the sum and difference can be calculated as follows:

[0244] • The sum of the two differences to be considered, or

[0245] • The arithmetic or geometric mean of the two differences to be considered, or

[0246] • The weighted average of the two differences to be considered.

[0247] In one variant, when determining the sum and difference, the model can weight the following differently:

[0248] The difference between titanium allocation and titanium distribution, and

[0249] The difference between characteristic assignment and characteristic distribution

[0250] For example, when looking for the minimum of the sum and difference, the difference between the titanium allocation and the titanium distribution can be considered two or three times, because the amount of titanium dioxide significantly affects the CTE and therefore must be taken into special consideration for the intended use.

[0251] In one implementation, the minimum sum and difference are understood to mean

[0252] • Based on the maximum value of titanium distribution, the difference between the titanium allocation and the titanium distribution on the substrate precursor surface of more than 75%, particularly more than 85%, particularly more than 90%, is less than 1.5%, particularly less than 1.0%, particularly less than 0.5%, and

[0253] • Based on the maximum value of the characteristic distribution, the difference between the characteristic distribution and the characteristic distribution on more than 75%, particularly more than 85%, particularly more than 90% of the substrate precursor surface is less than 1.5%, particularly less than 1.0%, particularly less than 0.5%.

[0254] In one implementation, the minimum sum and difference are understood to mean

[0255] • The difference between the titanium distribution and the titanium allocation on at least 75%, particularly at least 85%, particularly at least 90% of the substrate precursor surface is less than 1.5%, particularly less than 1.0%, particularly less than 0.5% of the maximum value of the titanium distribution, and this surface is mirrored in a further step to form a mirror element, and

[0256] • The difference between the characteristic assignment and characteristic distribution on more than 75%, particularly more than 85%, particularly more than 90% of the substrate precursor surface is less than 1.5%, particularly less than 1.0%, particularly less than 0.5% of the maximum value of the characteristic distribution, and the surface is mirrored in a further step to form a mirror element.

[0257] The model used in this variant is functionally dependent on

[0258] • The arrangement of multiple glass sections in the first glass component relative to each other.

[0259] • The spatial titanium curve and spatial property curve for each glass segment within the glassy body, and

[0260] • The effects of pushing together and rotating together on the spatial titanium curve and spatial characteristic curve in the glassy part.

[0261] Therefore, aspects related to titanium dioxide and at least one other property (e.g., ODC, Ti3+, etc.) are considered in the calculation of the optimal arrangement of the glass portion.

[0262] Based on the solution space of possible arrangements of the vitreous portions relative to each other, the optimal possible arrangement of the vitreous portions is determined by permutation. In this case, the objective is to minimize the sum and difference, which includes...

[0263] The difference between titanium allocation and titanium distribution, and

[0264] • The second difference between at least one characteristic assignment and at least one characteristic distribution.

[0265] Subsequently, the vitreous body is positioned so that, during the connection step, the vitreous body is connected according to the calculated optimal possible arrangement.

[0266] One implementation is characterized in that the sum of the differences is less than 1.5% of the sum of the maximum value of the titanium distribution and the maximum value of the property distribution, particularly less than 1.0%, and particularly less than 0.5%.

[0267] A feature of an implementation plan is that

[0268] The difference between titanium allocation and titanium distribution is less than 1.5% of the maximum value of titanium distribution, especially less than 1.0%, and especially less than 0.5%.

[0269] • The second difference between at least one characteristic assignment and at least one characteristic distribution is less than 1.5% of the maximum value of the relevant characteristic distribution, especially less than 1.0%, especially less than 0.5%.

[0270] This implementation is particularly well-suited for meeting the high requirements of EUV substrate precursors. Substrate precursors with a difference and a second difference higher than the listed values ​​are generally not suitable for producing mirror substrates with a deviation of less than 3 nm from the predicted line edge.

[0271] A feature of an implementation plan is that

[0272] The difference between titanium allocation and titanium distribution is between 0.15% and 1% of the maximum value of titanium distribution.

[0273] and

[0274] Second worst

[0275] The value of Ti3+ distribution is less than 5.0% of the maximum value of Ti3+ distribution, especially less than 2.0%, and...

[0276] The value of OH distribution is less than 2.0% of the maximum value of OH distribution, especially less than 1.0%, and especially less than 0.5%.

[0277] This implementation is particularly suitable for producing a substrate precursor from which a mirror substrate with a deviation of less than 3 nm from the edge of the predicted line can be generated.

[0278] One embodiment is characterized in that the step of preparing the vitreous body includes at least the following steps:

[0279] • The formation of porous soot bodies, with macroscopic production-related titanium curves extending along the longitudinal axis.

[0280] Furthermore, the layered structure related to the microscopic process extends along the growth axis.

[0281] • Vitrify the soot to produce a cylindrical glass body.

[0282] In one embodiment of the present invention, the step of generating porous soot includes the following method steps:

[0283] • Provide liquid SiO2 feedstock containing more than 60% by weight of polyalkylsiloxane D4.

[0284] • Evaporate the liquid SiO2 raw material into gaseous SiO2 raw material vapor.

[0285] • Evaporate the liquid TiO2 raw material into gaseous TiO2 raw material vapor.

[0286] • Convert SiO2 and TiO2 feed vapors into SiO2 and TiO2 particles.

[0287] • SiO2 and TiO2 particles are deposited on the deposition surface to form a porous soot body.

[0288] Octamethylcyclotetrasiloxane (also referred to herein as D4) forms the major component during the preparation of the soot. The preparation of the soot according to the aforementioned steps reduces the thickness of the macroscopic production-related titanium dioxide profiles and / or characteristic profiles.

[0289] One embodiment is characterized by heating the first glass component prior to the step of pushing them together. Heating causes the first glass component to become at least partially viscous, which facilitates mechanical deformation. Heating can be performed using either a flame-based or flameless thermal process.

[0290] One implementation is characterized in that the connection occurs at the relevant contact surfaces of the glass portion.

[0291] The features disclosed in the specification may be necessary for different embodiments of the claimed invention (individually and in any combination of each other).

[0292] The values ​​specified for the difference, sum difference, and second difference are relative values, which relate to the relevant distribution, i.e., the relevant quantities sought in the substrate precursor.

[0293] In this document, embodiments that disclose two or more features, each having a preferred range or alternative, should be understood to include all possible combinations of these features.

[0294] In this specification, the range specification also includes values ​​designated as limits. Therefore, the specification "within the range of X to Y" relative to the type of variable A means that A can assume values ​​X, Y, and values ​​between X and Y. Therefore, the range "at most Y" defined on one side of the type of variable A means as the value Y and less than Y.

[0295] The invention is further illustrated below by way of example and with reference to the accompanying drawings. The invention is not limited to the drawings.

[0296] Attached Figure

[0297] It is shown that:

[0298] Figure 1 The formation of soot bodies,

[0299] Figure 2 Vitrify the soot into a glassy substance.

[0300] Figure 3 vitreous body

[0301] Figure 4 The vitreous portion resulting from the splitting of the vitreous body.

[0302] Figure 5Representation of two-dimensional, macroscopic, production-related titanium curves in the vitreous portion.

[0303] Figure 6 The arrangement of the two vitreous parts,

[0304] Figure 7a Substrate precursor,

[0305] Figure 7b Representation of titanium curves for multiple glassy portions compared to the desired titanium distribution.

[0306] Figure 8 Additional illustrations of titanium profiles for multiple glassy portions compared to the desired titanium distribution.

[0307] Figure 9 First homogenization process,

[0308] Figure 10 The first glass components are pushed together.

[0309] Figure 11 Second homogenization process, and

[0310] Figure 12 Representation of the method according to the present invention. Attached Figure Description

[0311] Figure 1 An apparatus 100 for preparing titanium-doped SiO2 soot 200 is shown. A plurality of flame hydrolysis burners 220 arranged in a row are arranged along a carrier tube 210 made of alumina.

[0312] Silica and titanium dioxide raw materials are fed into the reaction zone of the flame hydrolysis burner 220 in gaseous form, where they are decomposed through oxidation and / or hydrolysis and / or pyrolysis. In the reaction zone, SiO2 and TiO2 particles are formed, both deposited in layers on the carrier tube 210, thereby forming SiO2-TiO2 soot body 200. The SiO2-TiO2 particles themselves exist as agglomerates or aggregates of primary SiO2 particles with particle sizes in the nanometer range. In particular, due to its layered structure, the soot body 200 may include a microlayered structure.

[0313] In particular, when preparing a cylindrical soot body 200 with a large volume of 1100, in order to prepare a substrate precursor 900 with a mass greater than 50 kg, especially greater than 100 kg, especially greater than 200 kg, a flame hydrolysis burner 220 can be mounted on a common burner block, which moves back and forth between two rotation points fixed relative to the longitudinal axis of the carrier tube 210 parallel to the longitudinal axis.

[0314] Such movement of the flame hydrolysis burner 220, mechanical inaccuracies in the raw materials or feed line of the burner 220, or changes in process temperature may also cause spatial fluctuations in the macroscopic production-related physical properties (such as TiO2 content) of the soot 200.

[0315] Figure 2 The vitrification of soot 200 is illustrated. Vitrification is preferably carried out in a processing chamber. Preferably, the vitrification temperature is in the range of 1200°C to 1500°C, more preferably 1250°C to 1350°C. To avoid the formation of bubbles in the subsequent quartz glass, it has proven advantageous that the pressure inside the processing chamber is lower than the pressure outside the processing chamber during vitrification, i.e., vitrification is carried out under reduced pressure. Furthermore, this has the advantage that the material of the processing chamber is not affected by corrosive and aggressive gases and thus suffers reduced abrasion. Therefore, it is preferred that the embodiment in which vitrification is preferably carried out at a pressure of less than 1 mbar. Within the vitrification range, soot 200 can be moved through the vitrification furnace 250 according to the movement arrow 251.

[0316] Due to vitrification, a glass body 300 with a titanium dioxide content of 3% to a maximum of 10% by weight is produced from the soot body 200. The production-related physical property fluctuations that occur in the soot body 200 are transferred to the glass body 300, resulting in the glass body having…

[0317] • Macroscopic production-related titanium curves, and

[0318] • Microscopic production-related layer structure.

[0319] The specified 3% to a maximum of 10% by weight of titanium is related to the amount of TiO2 (titanium dioxide), not the amount of elemental titanium.

[0320] Figure 3 A cylindrical glass body 300 is shown. Dashed lines indicate portions cut from the glass body within the range of the 1200-degree segmentation step. The resulting rod-shaped glass body portion 400 is shown in... Figure 4 In particular, the glass body 300 can be divided into a plurality of rod-shaped glass body portions 400 having a longitudinal axis 440. In particular, the glass body portions 400 can have a circular fan-shaped cross-section.

[0321] Through the first homogenization process 1600 of the first glass component and the second homogenization process 2000 of the second glass component, the microscopic production-related layer structure is greatly reduced, making the glass body portion 400 essentially free of layer structure. However, the two homogenization processes 1600 and 2000 do not allow the substrate precursor 900 to lack a long-wavelength titanium profile, which substantially affects the quality and usability of the substrate precursor 900 in EUV lithography.

[0322] Figure 4 The glassy portion 400 is shown, on which a titanium curve 410 is spatially measured. For this purpose, the titanium dioxide content is measured at multiple measurement points (P1, P2, P3, P4, P5, P6) along the longitudinal axis 420. The distance between these measurement points is less than 5 cm, and particularly less than 2 cm. This point-by-point measurement of the titanium dioxide content provides a clear picture of the ratio within the glassy portion 400. Any fluctuations in the titanium curve occur on a length scale of 0.15 m to 0.75 m.

[0323] Furthermore, due to mechanical influences, further macroscopic production-related changes in the chemical and / or physical properties of the glass 300 can occur within the preparation 1100 of the soot body 200. At least one of these changes, represented as characteristic curve 510, can also be determined in the measurement 1300 step. The following chemical and / or physical properties with macroscopic production-related characteristic curve 510 can be measured individually or in any combination: OH content, CTE, fluorine content, bubble content, ODC content, Ti3+ content, and metal impurity content.

[0324] Characteristic curve 510 can be measured parallel to and similarly to titanium curve 410. For this purpose, physical properties are measured at multiple measurement points (P1, P2, P3, P4, P5, P6) along the longitudinal axis 420. Again, the distance between the measurement points is less than 5 cm, and particularly less than 2 cm.

[0325] Figure 5 The results of measurements 1300 of the titanium curve 410 and characteristic curve 510 in the glass portion 400 are schematically shown. The amounts, expressed as weight percent of titanium dioxide or as ppm of characteristics, are plotted as a function of position along the longitudinal axis 440 of the glass portion 400. For simplicity, in... Figure 4 and Figure 5 The measurement results for only six measurement points (P1, P2, P3, P4, P5, P6) are shown.

[0326] The steps and / or aspects of the spatial measurement 1300 of the titanium curve 410 described below are also applicable to the spatial measurement of at least one characteristic curve 510.

[0327] As can be seen from the figure, the titanium dioxide content is within a predefined range of 3% to 10% by weight. However, for production-related reasons, the titanium dioxide content fluctuates between 5.4% and 6.1% by weight along the longitudinal axis 420 of the glass body portion 400.

[0328] The quantities of the characteristic measured at six measurement points (P1, P2, P3, P4) (OH content in ppm is used as an example here) are also shown as characteristic curve 510. For production-related reasons, this OH content fluctuates between 150 ppm and 175 ppm along the longitudinal axis 420 of the glass body portion 400.

[0329] Figure 6 A connection 1500 is shown for the plurality (in this case, two) rod-shaped glass body portions 400, 400' used to form an elongated first glass component 600.

[0330] For this purpose, the planar contact surfaces 401 of the first glass portion 400 and the planar contact surfaces 401' of the second glass portion 400' can be joined together by twisting and welding. This is a "cold joining method" in which the adjacent areas of at most contact surfaces undergo significant heating.

[0331] Alternatively, connection 1500 may include a joining step in which two glass portions 400, 400' are softened and joined together in a furnace. This is a "thermal joining method" in which the individual glass portions 400, 400' are joined together by welding. As described, titanium dioxide curves and / or characteristic curves are measured at multiple measurement points. For glass portion 400, by example, titanium curve 410 is measured at measurement points P1, P2, P3, P4, P5, P6. For glass portion 400', by example, titanium curve 410' is measured at measurement points P7, P8, P9, P10, P11, P12.

[0332] Therefore, within the scope of this method, at least three, particularly at least five, particularly at least eight glass portions can be connected to each other to form a first glass component 600, which also... Figure 9 As shown in the image.

[0333] like Figure 5 As shown, the titanium curve 410 oscillates along the longitudinal axis of the glass portion 400. However, the titanium curve also oscillates between different glass portions 400, 400'. In the prior art, these macroscopic production-related fluctuations in the individual titanium curves between different glass portions 400, 400' have not been further considered. Instead, for substrate precursors 900 with low mass to date, only a few, particularly only two, glass portions 400, 400' are required, making the fluctuations occurring between the long-wavelength titanium curves 410 in the glass portions 400, 400' negligible. This is no longer possible in the preparation of substrate precursors with masses greater than 50 kg, particularly greater than 100 kg, especially if at least four glass portions must be connected to each other.

[0334] Figure 7a, Figure 7b and Figure 8 The figure illustrates the steps used within the range of measuring 1300, which are designed to overcome the aforementioned drawbacks.

[0335] What needs to be explained is how, with the help of a model, the titanium distribution 430 is calculated in each case by means of the arrangement of the glass portions 400, 400', 400”, 400”' relative to each other, and compared with the desired titanium distribution 420.

[0336] The steps and / or aspects described below for minimizing the difference between titanium allocation and titanium distribution are also applicable to minimizing a second difference between at least one property allocation and at least one property distribution.

[0337] The starting point is a predetermined desired titanium distribution 420 in the 1400 substrate precursor. In one variation, the titanium distribution 420 represents a two-dimensional distribution of the amount of TiO2 in the substrate precursor, particularly along the centerline, especially at the outer surface which will be mirrored later, through the substrate precursor. In this embodiment, the model can calculate the two-dimensional titanium distribution in the substrate precursor from two-dimensionally determined titanium curves and their arrangement relative to each other.

[0338] Figure 7a A substrate precursor 900 is shown. Ideally, this substrate precursor should have a titanium distribution 420, such as... Figure 7b The upper curve is shown in the figure. By way of example, a parabolic titanium distribution with a maximum value at the center of the substrate precursor is found in the range of 4.75 wt% to 5.5 wt% TiO2.

[0339] The desired two-dimensional titanium distribution 420 can be found in the substrate precursor 900 along the centerline 920 on the outer surface 910 for later mirroring. The type and design of the titanium distribution 420 can particularly depend on the type and conditions of use of the EUV mirror later. A titanium distribution having a parabolic (or Gaussian) curve with a maximum value at the center of the substrate precursor is particularly preferred. In particular, the titanium distribution, and therefore the CTE, can be adapted to the distribution of incident EUV radiation.

[0340] To illustrate the procedure, let's assume that... Figure 7b The intermediate substrate precursor 900 is formed by only four glass portions 400, 400', 400'', and 400"'. It is similar to... Figure 6 They are arranged relative to each other in such a way that they form a rod-shaped glass body 300. In this case, the four glass body portions 400, 400', 400'', and 400"' are joined together in the following arrangement to form the first glass component 600:

[0341] • The end of the vitreous portion 400 is connected to the front of the vitreous portion 400' (point E2).

[0342] • The end of the vitreous portion 400' is connected to the front of the vitreous portion 400'' (point E3).

[0343] • The end of the vitreous portion 400'' is connected to the front of the vitreous portion 400”' (point E4).

[0344] Figure 7b The central curve plot shows the titanium curves 410, 410', 410', 410'', and 410'' of four glass segments 400, 400'', 400'', and 410'' generated by at least one glass segment 300. A set of measurements of the amount of TiO2 (in weight %) in each of the four glass segments 400, 400'', 400'', and 400'' are plotted.

[0345] To overcome the aforementioned drawbacks, a model capable of calculating titanium allocation 430 in the substrate precursor 900 is used. In this case, the model uses the following as input parameters:

[0346] • The arrangement of multiple glass portions 400, 400', 400'', 400"' relative to each other in the first glass component 600.

[0347] • The space titanium curves 410, 410', 410”, and 410”’ in each of the vitreous portions 400, 400', 400”’, and

[0348] • Push together at 1700 degrees and rotate at 1800 degrees for the vitreous body part at 400 degrees.

[0349] The effect of spatial titanium curves 410, 410', 410”, 410” in 400', 400'', 400”'.

[0350] Based on this arrangement, the model calculates the titanium allocation 430 in the substrate precursor 900. Titanium allocation 430 in... Figure 7b The curve below is shown.

[0351] like Figure 7bAs shown, the calculated titanium distribution 430 curves do not simply correspond to a linear sequence of the titanium curves 410, 410', 410”, 410”' in the assumed arrangement. Instead, the method steps disclosed herein result in the spatial positions and orientations of the titanium curves 410, 410', 410”, 410”' no longer corresponding to the spatial positions of the glass portions 400, 400', 400'', 400”' in the first glass body 300. Therefore, the spatial orientation of the titanium curves 410, 410', 410”, 410”' changes, necessitating a model to calculate the position and amount of TiO2 in the titanium distribution 430 of the substrate precursor 900.

[0352] Figure 7b The calculated titanium distribution 430 shown has a zigzag curve and therefore deviates significantly from the desired parabolic titanium distribution 420.

[0353] To achieve the optimal arrangement, the possible arrangements of the glass portion are considered. In the model, the effect of all possible arrangements of the glass portion on the titanium distribution 430 is calculated. Figure 8 This is intended to illustrate the point. The starting point is the arrangement of four glass portions 400, 400', 400'', 400"' that deviates from Figure 7, which are joined together to form the first glass component 600 in the following arrangement:

[0354] • The end of the vitreous portion 400'' is connected to the front of the vitreous portion 400”' (point E2).

[0355] • The end of the 400”' vitreous portion is connected to the front of the 400”' vitreous portion (point E3).

[0356] • The end of the vitreous portion 400' is connected to the front of the vitreous portion 400 (point E4).

[0357] The model calculates the titanium distribution 430' in the substrate precursor 900 from titanium curves 410, 410', 410”, and 410”'. Figure 7b Compared to the titanium distribution 430 shown, this titanium distribution 430' is more similar to the desired titanium distribution 420 in both quantity and curve.

[0358] Specifically, the model calculates the corresponding titanium distributions 430, 430' from any possible arrangement of the glass portions 400, 400'', 400"' and compares them with the desired titanium distribution 420. For this purpose, all possible arrangements of the glass portions 400, 400'', 400"' are arranged. Based on this information, the model forms the difference between the titanium distribution and the titanium distribution 420 in each case. The optimal arrangement is one in which the magnitude of the difference between two spatially identical points on the substrate precursor, and in particular the maximum magnitude of the difference, is minimized.

[0359] Subsequently, the glass sections 400, 400', 400'', and 400”' are positioned and connected according to the optimal arrangement.

[0360] Similarly, in addition to the titanium distribution, at least one characteristic distribution can represent a second target value that is optimally achieved and / or sought in the substrate precursor 900. The model used in this variant is functionally dependent on...

[0361] • The arrangement of multiple glass portions 400, 400', 400'', 400"' relative to each other in the first glass component 600.

[0362] • The space titanium curves 410, 410', 410”, 410”' and space property curve 510 in each of the vitreous portions 400, 400', 400”', and 400”', and

[0363] • The effects of pushing together and rotating together on the spatial titanium curves 410, 410, 410”, 410” and spatial characteristic curve 510 in the glass body section at 400, 400', 400'', 400”'.

[0364] Therefore, aspects related to elemental titanium dioxide and at least one other property (e.g., ODC, Ti3+, etc.) are considered in the calculation of the optimal arrangement of the glass portion.

[0365] Based on the solution space of possible arrangements of the glass portions relative to each other, the optimal possible arrangement of glass portions 400, 400', 400'', and 400"' is determined. In this case, the objective is to minimize the sum of differences, which includes...

[0366] The difference between titanium allocation and titanium distribution, and

[0367] • The second difference between at least one characteristic assignment and at least one characteristic distribution.

[0368] Figure 9A first homogenization process 1600 is shown for a first glass component 600, which is produced from glass body portions 400, 400', 400'', 400"'. Both the glass body and the first glass component 600 produced from the glass body portions 400, 400', 400'', 400"' include microscopic, production-related layer structures. To reduce this and / or to enable the fabrication of a substrate precursor 900 that is substantially free of layer structures, two homogenization processes are performed sequentially.

[0369] In the first homogenization process 1600, the first glass component 600 is clamped into a glass lathe 605 equipped with one or more burners 220 and homogenized by a reshaping process as described in EP 673 888A1 in order to completely remove the layer structure.

[0370] The glass lathe 605 has two chucks 610, 610', which can be rotated independently of each other by 650, 650'. A first glass component 600 is clamped between the two chucks 610, 610'. Two retaining elements 620, 620' ensure a better fit between the chucks 610, 610' and the first glass component 600. The first glass component 600 is heated at multiple points by the burner 220 and softened in the process, creating a shear zone 630. This shear zone 630 allows external forces such as torsional, tensile, or compressive forces to be introduced onto the rod-shaped first glass component 600. Within the shear zone 630, regions with different stresses or experiencing different movements are thus created, which is associated with shear effects or expansion and compression effects. To generate this force, the two chucks 610, 610' can be rotated in opposite directions by 650, 650' in each case.

[0371] In the first homogenization process 1600, the microscopic production-related layer structures in the plane of the shear region of the first glass component 600 are effectively reduced. However, the reduction in the microscopic production-related layer structures perpendicular to the plane of the shear region of the first glass component 600 is significantly less.

[0372] In order to eliminate any remaining residue of the layered structure in the second homogenization process 2000, the first glass component 600 must be reshaped. Figure 10The diagram illustrates pushing the first glass components 600 together 1700 to produce a spherical glass system 700. For this purpose, the first glass components 600 are heated and compressed by a burner 220. The pushing together 1700 can occur because the two chucks 610, 610' move toward each other, as indicated by movement arrow 612. The glass system 700 is then rotated 1800 more than 70 degrees. For this purpose, the glass system 700 is removed from the chucks 610, 610' and rotated, as indicated by movement arrow 615. This rotation ensures that, in the second homogenization process 2000, portions of the layer structure that were only slightly compensated or not compensated at all in the first homogenization process 1600 can be effectively reduced. After the glass system 700 has been rotated 1800 more than 70 degrees, the system is again clamped into the chucks 610, 610'. This is followed by a stretching of the glass system 700 1900. This mechanical reshaping of the spherical glass system 700 into an elongated second glass component 800 occurs by heating the glass system 700 using a burner 220 and moving the chucks 610, 610' away from each other, as indicated by the movement arrow 613.

[0373] Figure 11 The second homogenization process 2000 of the second glass component 800 is shown. The second homogenization process 2000 is substantially similar to the first homogenization process 1600. The decisive difference is that, by rotation 1800, the layer structure previously substantially perpendicular to the longitudinal axis of the glass lathe 605 is now positioned in the direction of the longitudinal axis of the glass lathe 605. The second glass component 800 is clamped between two chucks 610, 610' of the glass lathe 605. The second glass component 800 is heated at multiple points by a burner 220 and softened in the process, resulting in a second shear zone 640. This second shear zone 640 allows external forces such as torsional, tensile, or compressive forces to be introduced onto the rod-shaped second glass component 800. Within the second shear zone 640, regions with different stresses or undergoing different movements are thus created, which are associated with shear effects or expansion and compression effects. To generate this force, the two chucks 610, 610' can be rotated 650, 650' in opposite directions in each case.

[0374] In the second homogenization process 2000, the microscopic production-related layer structures are effectively reduced in the direction perpendicular to the longitudinal axis of the first glass component 600 and / or in the direction perpendicular to the longitudinal axis of the second glass component 800. After the first homogenization process 1600 and the second homogenization process 2000, a substrate precursor 900 that is substantially free of layer structures is produced.

[0375] Figure 12 A process is shown for preparing a substrate precursor 900 containing a TiO2-SiO2 mixed glass with a mass greater than 100 kg. It includes the following steps:

[0376] • Introduce silica and titanium dioxide raw materials into the flame at 1000°C.

[0377] • Prepare a glassy body with a titanium dioxide content of 3% to a maximum of 10% by weight, wherein the glassy body has the following characteristics:

[0378] • Macroscopic production-related titanium curves, and

[0379] • Possesses a microscopic, production-related layered structure,

[0380] • Divide the vitreous body into 1200 rod-shaped segments.

[0381] • Spatial measurement of titanium profiles in each of the 1300 glass segments.

[0382] • Connect the 1500 glass sections to form an elongated first glass component.

[0383] • First homogenization treatment of the first glass component 1600,

[0384] • Push the first glass components together at 1700 degrees to create a spherical glass system.

[0385] • Rotate the 1800° glass system more than 70 degrees.

[0386] • Stretch the 1900 glass system to form an elongated second glass component.

[0387] • A second homogenization process 2000 is performed on the second glass component to produce a substrate precursor 900, which is substantially free of layer structures.

[0388] The method is characterized in that the step of measuring 1300 includes the following steps:

[0389] • Predetermine the desired spatial titanium distribution in the 1400 substrate precursor 900.

[0390] • Provides a model for titanium allocation in the 1420 substrate precursor 900, which depends on

[0391] • The arrangement of multiple glass sections in the first glass component relative to each other.

[0392] • The spatial titanium curve in each glass segment of the vitreous body, and

[0393] • The effects of pushing and rotating steps on the spatial titanium curve within the glassy portion.

[0394] • The optimal arrangement of the 1450 glass components relative to each other was calculated using a model to minimize the difference between the titanium distribution and the titanium allocation.

[0395] • Position the 1470 glass portion so that, during the connection step, the glass portion is connected according to the calculated optimal arrangement.

[0396] Figure Labels

[0397] 100 devices

[0398] 200 soot bodies

[0399] 210 Carrier tube

[0400] 220 burner or flame hydrolysis burner

[0401] 225 Flames

[0402] 250 vitrification furnace

[0403] 251 Moving Arrow

[0404] 300 Vitreous

[0405] 400, 400', 400'' Vitreous portion

[0406] 401, 401' contact surfaces

[0407] 410, 400', 400”, 400”' Titanium Curves

[0408] 420 Titanium Distribution

[0409] 430 Titanium Allocation

[0410] 440 Longitudinal axis

[0411] 510 Characteristic Curve

[0412] 600 First Glass Component

[0413] 605 Glass Lathe

[0414] 610, 610' chuck

[0415] 612 Moving Arrow

[0416] 613 Moving Arrow

[0417] 615 Moving Arrow

[0418] 620 and 620' are two holding elements.

[0419] 630 Shearing Zone

[0420] 640 Second shear zone

[0421] 650°, 650° rotation

[0422] 700 Spherical Glass System

[0423] 800 Second Glass Component

[0424] 900 substrate precursor

[0425] 910 Outer Surface

[0426] 920 center line

[0427] 1000 Introduction

[0428] 1100 Preparation

[0429] 1200 split

[0430] 1300 Space Measurement

[0431] 1400 Predetermined

[0432] 1420 provides the model

[0433] 1450 Calculate the optimal layout

[0434] 1470 Positioning the vitreous body portion

[0435] 1500 Connecting glass portion

[0436] 1600 First homogenization treatment

[0437] 1700 pushed together

[0438] 180° Rotating Glass System

[0439] 1900 stretch

[0440] 2000 Second homogenization treatment

Claims

1. A method for preparing a substrate precursor (900) containing a TiO2-SiO2 mixed glass with a mass greater than 50 kg, the method comprising the following steps: • Introduce silica raw materials and titanium dioxide raw materials into the flame (225). • Prepare a glass body (300) with a titanium dioxide content of 3% to a maximum of 10% by weight, said glass body (300) comprising: • Macroscopic production-related titanium curves (410, 410', 410'', 410'''), and • Microscopic production-related layer structure • Divide the glass body into multiple rod-shaped glass body segments (400, 400', 400'', 400'''). • Spatial measurement of the titanium curve (410, 410', 410'', 410'') in each of the glass portions (400, 400', 400'''). • Connect the glass portions (400, 400', 400'', 400''') to form an elongated first glass component (600). • The first homogenization treatment of the first glass component (600), • Push the first glass components (600) together to create a spherical glass system (700). • Rotate the glass system (700) more than 70 degrees. • Stretch the glass system (700) to form an elongated second glass component (800). • A second homogenization treatment of the second glass component (800) to produce a substrate precursor (900), wherein the microscopic production-related layer structures in the substrate precursor (900) are removed by at least 99% compared to the glass body. Its features are, The measurement process includes the following steps: • The desired spatial titanium distribution (420) in the substrate precursor (900) is determined in advance. • Provide a model of titanium allocation (430) in the substrate precursor (900), the model depending on • The arrangement of the plurality of glass portions (400, 400', 400'', 400''') in the first glass component (600) relative to each other, • The spatial titanium curves (410, 410', 410'', 410''') in each of the glassy portions (400, 400', 400'''), and • The effects of the pushing and rotating steps on the spatial titanium curve (410, 410', 410'', 410''') in the glassy portion. • The optimal arrangement of the glass portions (400, 400', 400'', 400''') relative to each other is calculated using the model, such that the difference between the titanium distribution (430) and the titanium distribution (420) is minimized. • Position the glass body portions (400, 400', 400'', 400''') such that, during the connection step, the glass body portions (400, 400', 400'', 400''') are connected according to the calculated optimal arrangement.

2. The method according to claim 1, characterized in that, The substrate precursor (900) has a mass greater than 100 kg.

3. The method according to claim 1 or claim 2, characterized in that, The method includes the following steps: • Prepare a second glassy body having a titanium dioxide content of 3% to a maximum of 10% by weight, the second glassy body comprising: • The second macroscopic production-related titanium curve, and • The second microscopic production-related layer structure • Divide the second glass body into multiple rod-shaped glass body segments.

4. The method according to claim 1 or 2, characterized in that, At least three glass portions are connected to form the first glass component.

5. The method according to claim 1 or 2, characterized in that... Based on the maximum value of the titanium distribution (420), the difference between the titanium allocation (430) and the titanium distribution (420) is less than 1.5%.

6. The method according to claim 1 or 2, characterized in that, The vitreous body includes at least one of the following characteristic curves (510): • Macroscopic production-related OH curves • Macro-level production-related CTE curves • Macroscopic production-related fluorine curves • Macroscopic production-related bubble curves • Macro-level production-related ODC curves • Macroscopic Ti3+ curves related to production. • Macroscopic production-related metal impurity curves.

7. The method according to claim 6, characterized in that, In the measurement step, at least one characteristic curve of the characteristic curve (510) is measured in each of the glass portions (400, 400', 400'', 400''').

8. The method according to claim 7, characterized in that, The measurement process includes the following steps: • The desired spatial characteristic distribution in the substrate precursor (900) is determined in advance. • Provide a model of the characteristic assignment in the substrate precursor (900), the model depending on • The arrangement of the plurality of glass portions in the first glass component relative to each other, • The spatial characteristic curve (510) of each of the glass segments, and • The effect of the pushing and rotating steps on the spatial characteristic curve in the vitreous portion. • Calculate the optimal possible arrangement of the vitreous portions (400, 400', 400'', 400''') relative to each other using the model, such that the sum and difference are minimized, the sum and difference including The difference between the titanium distribution (430) and the titanium distribution (420), and • The second difference between the characteristic assignment and the characteristic distribution, • Position the glass body portions (400, 400', 400'', 400''') such that, during the connection step, the glass body portions (400, 400', 400'', 400''') are connected according to the calculated best possible arrangement.

9. The method according to claim 8, characterized in that, The sum of the maximum value of the titanium distribution (420) and the maximum value of the characteristic distribution is less than 1.5%.

10. The method according to claim 1 or 2, characterized in that, The step of preparing the glass body includes at least the following steps: • A porous soot body (200) is generated, wherein the macroscopic production-related titanium profile extends along the longitudinal axis, and the microscopic process-related layer structure extends along the growth axis. • Vitrify the soot to produce a cylindrical glass body.

11. The method according to claim 1 or 2, characterized in that, The first glass component (600) is heated before the step of pushing them together.

12. The method according to claim 1 or 2, characterized in that, The connection occurs at the relevant contact surface (401) of the glass portion (400, 400', 400'', 400''').

13. The method according to claim 1, characterized in that, The substrate precursor (900) does not contain a layer structure.

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