Ultra-low expansion coefficient fluorinated quartz glass and preparation method thereof

Abstract

The present invention discloses an ultra-low thermal expansion coefficient fluorinated quartz glass and a preparation method thereof. The preparation method comprises first preparing a TiO2-SiO2 composite material, then fluorinating the obtained TiO2-SiO2 composite material with a fluorine source, pressing the resulting composite material into a dense body, and finally vitrifying and sintering the dense body. The prepared fluorinated quartz glass has an extremely low thermal expansion coefficient of less than 5×10-8 / K and can be used as a mirror substrate in EUV lithography. The preparation method of the present invention can produce extremely high-purity ultra-low thermal expansion coefficient fluorinated quartz glass, wherein the total amount of transition metal impurities in the raw material is controlled within 1 ppm. The transition metal impurity content and purity of the raw material can be increased through purification.

Description

Technical Field

[0001] The present invention belongs to the technical field of quartz glass, and in particular relates to an ultra-low expansion coefficient fluorinated quartz glass and a preparation method thereof. Background Art

[0002] The coefficient of expansion of glass is an important term in physics. It refers to the ratio of the change in length of an object due to a change in temperature. It is defined as: compression coefficient × temperature change × original length. This determines whether an object will expand or contract according to the coefficient of expansion when the temperature changes.

[0003] There are two types of glass expansion coefficients: linear expansion coefficient and volumetric expansion coefficient. The linear expansion coefficient is defined as the rate at which an object's length increases or decreases for every 1°C increase in temperature. The volumetric expansion coefficient is defined as the rate at which an object's volume increases or decreases for every 1°C increase in specific volume.

[0004] The coefficient of expansion of glass has a wide range of applications, significantly impacting the construction and manufacturing of many everyday products. For example, many highly detailed products made of glass require adjusting the coefficient of expansion of the glass according to varying temperatures to ensure product quality and dimensional accuracy.

[0005] Therefore, when manufacturing or using products that require glass, the expansion coefficient of the glass should be effectively managed to avoid problems caused by temperature changes. Only by correctly controlling the expansion coefficient of the glass can the dimensional and quality accuracy of the product be guaranteed.

[0006] In EUV lithography, highly integrated structures with line widths of less than 50 nanometers are produced using microlithographic projection systems. Radiation from the EUV range (extreme ultraviolet light, also known as soft X-ray radiation) with a wavelength of approximately 13 nanometers is used. The projection system is equipped with a mirror element made of Ti-doped quartz glass with a reflective layer system. These materials are characterized by an extremely low linear thermal expansion coefficient, which can be adjusted via the titanium concentration. Typical titanium dioxide concentrations are 6% to 9% by weight.

[0007] In the intended use of such a blank made of synthetic titanium-doped glass with a high silica content as a mirror substrate, its upper side is mirror-like. The maximum (theoretical) reflectivity of such an EUV mirror element is approximately 70%, but at least 30% of the radiant energy is absorbed in the coating or in the near-surface layer of the mirror substrate and converted into heat. This results in an inhomogeneous temperature distribution within the volume of the mirror substrate, with temperature differences of up to 50°C.

[0008] To minimize deformation, it is desirable for the glass of the mirror substrate blank to have a linear thermal expansion coefficient of zero over the entire temperature range of operating temperatures encountered during use. However, in reality, the temperature range within which the linear thermal expansion coefficient is approximately zero is very narrow for Ti-doped quartz glass.

[0009] Patent CN113631522A discloses titanium-containing quartz glass with excellent UV absorption. The quartz glass absorbs ultraviolet light with a wavelength of 250 nm or shorter, preventing the adverse effects of ozone production on the human body. The transmittance of the quartz glass in the near-ultraviolet to visible light range does not decrease due to color development upon UV irradiation, suppressing accumulation of absorption or deformation caused by lamp failure. This is due to structural changes in the quartz glass within the 200-300 nm range upon UV irradiation. Furthermore, even after UV exposure, the transmittance within the intended wavelength range does not decrease. However, the titanium content of this titanium-containing quartz glass is low, resulting in minimal changes in the linear thermal expansion coefficient of the quartz glass.

[0010] Patent CN113568093A relates to a titanium-doped silica optical fiber, its preparation method, and its application. The titanium-doped silica optical fiber comprises, from the inside out, a core, a core cladding, a titanium diffusion layer, and an organic cladding. The core cladding is a silica cladding, and the titanium diffusion layer is a titanium-doped silica cladding. The core cladding and titanium diffusion layer are geometrically concentric with the core. The preparation method comprises: injecting metallic titanium into a silica optical fiber preform using high-energy plasma under vacuum conditions to form a titanium-doped silica cladding; drawing the resulting titanium-doped silica optical fiber preform to produce silica glass fiber yarns; and coating the resulting silica glass fiber yarns with an organic cladding. However, due to the high-energy plasma implantation method for titanium doping, the preparation conditions and requirements are complex, making large-scale production difficult. Furthermore, the uniformity of the doping cannot be effectively achieved.

[0011] CN106430913A is about a method for preparing quartz glass with a low expansion coefficient and quartz glass, which relates to the field of quartz glass preparation. The main purpose is to prepare quartz glass with a low expansion coefficient, and solve the problem that the valence state of titanium ions in low-expansion quartz glass cannot be controlled at present, resulting in unstable optical properties and inability to be applied in aerospace, extreme ultraviolet lithography and other fields. The method comprises: introducing an oxidizing atmosphere into the sintering space to place the sintering space in an oxidizing environment, sintering the titanium-doped silica loose body; cooling the transparent quartz glass obtained after sintering, and obtaining the finished quartz glass. This patent prepares quartz glass with a low expansion coefficient through a vapor deposition process, and its oxidizing environment can prevent Ti from oxidizing. 4+ Xiang Ti 3+ Transformation, but its preparation cost is high, OH - The high content of leads to extremely high absorption loss;

[0012] The titanium concentration is typically set to achieve a zero linear thermal expansion coefficient within the temperature range of 20°C to 45°C. Volumetric regions of the mirror substrate with temperatures above or below the preset zero temperature expand or contract, causing deformation that is detrimental to the mirror's imaging quality despite the TiO2-SiO2 glass's generally low linear thermal expansion coefficient. None of the three aforementioned patents (CN113631522A, CN113568093A, and CN106430913A) specifically address this issue. This phenomenon is primarily related to the glass's fictive temperature. The fictive temperature is a glass property that represents the degree of order in the "frozen" glass network. Higher fictive temperatures in TiO2-SiO2 glass are associated with lower order in the glass structure and greater deviations from the energetically optimal structural arrangement.

[0013] The fictive temperature is influenced by the thermal history of the glass, in particular by the final cooling process. During the final cooling process, the near-surface region of the glass block necessarily has different conditions than the central region, so that different volume regions of the mirror substrate blank already have different fictive temperatures due to their different thermal histories, which in turn are associated with corresponding inhomogeneities in the distribution of the linear thermal expansion coefficient. Summary of the Invention

[0014] In order to solve the above problems existing in the prior art, the present invention provides an ultra-low expansion coefficient fluorinated quartz glass and a preparation method thereof.

[0015] The technical solution adopted in the present invention is:

[0016] A method for preparing ultra-low expansion coefficient fluorinated quartz glass comprises the following steps:

[0017] (1) Preparation of TiO2-SiO2 composite materials:

[0018] Silicon source and titanium source are hydrolyzed under catalyst conditions to form TiO2-SiO2 composite material;

[0019] (2) Fluorinated TiO2-SiO2 composite materials:

[0020] fluorinating the TiO2-SiO2 composite material obtained in step (1) with a fluorine source to form a fluorinated TiO2-SiO2 composite material;

[0021] (3) Formation of ultra-low expansion coefficient fluorinated quartz glass:

[0022] The fluorinated TiO2-SiO2 composite material obtained in step (2) is pressed into a dense green body, and then the dense green body is subjected to a vitrification sintering process to obtain an ultra-low expansion coefficient fluorinated quartz glass.

[0023] The method for preparing the ultra-low expansion coefficient fluorinated quartz glass, in step (1), the silicon source is one or a mixture of silicates and their derivatives, organosilicon compounds, silicon salts containing organic acids, silicon-containing inorganic salts, and silicon dioxide;

[0024] The titanium source is one or a mixture of titanate and its derivatives, organic titanium compounds, titanium salts containing organic acids, inorganic salts containing titanium, and titanium dioxide.

[0025] In the method for preparing ultra-low expansion coefficient fluorinated quartz glass, in step (1), the catalyst is a fluorine-containing acid or salt.

[0026] In the method for preparing ultra-low expansion coefficient fluorinated quartz glass, the catalyst is ammonium bifluoride or hydrofluoric acid.

[0027] The method for preparing the ultra-low expansion coefficient fluorinated quartz glass is characterized in that the content of TiO2 in the TiO2-SiO2 composite material is 5-12wt%;

[0028] The particle size of the TiO2-SiO2 composite material is 10nm-5000nm;

[0029] The morphology of the TiO2-SiO2 composite material is spherical, hemispherical or angular;

[0030] The TiO2-SiO2 composite material is a core-shell structure, a sandwich structure, a yolk-shell structure, or a porous network cross-linked structure.

[0031] In the method for preparing ultra-low expansion coefficient fluorinated quartz glass, in step (2), the fluorine source is a gaseous fluorine source or a liquid fluorine source.

[0032] In the method for preparing the ultra-low expansion coefficient fluorinated quartz glass, the gaseous fluorine source is one or a mixture of sulfur hexafluoride, silicon tetrafluoride, hydrogen fluoride, and nitrogen fluoride;

[0033] The liquid fluorine source is one of ammonium hexafluorosilicate solution, ammonium bifluoride solution, and hydrofluoric acid solution, or a mixture of several of them.

[0034] In the method for preparing the ultra-low expansion coefficient fluorinated quartz glass, the temperature for fluorination of the liquid fluorine source is 20-95°C, and the temperature for fluorination of the gaseous fluorine source is 400-1200°C.

[0035] The fluorine content of the fluorinated TiO2-SiO2 composite material is 100ppm-106ppm.

[0036] The quartz glass prepared by the preparation method, in step (3), the dense green body is vitrified and sintered under the conditions of a temperature of 1450-2250°C and a vacuum degree of 10-1-103Pa.

[0037] The inventors of the present application have discovered through long-term research that, compared with conventional titanium-doped quartz glass, by fluorinating the quartz glass while doping it with titanium, and using a fluorine-containing acid or salt as a catalyst and providing a fluorine source during the material synthesis stage, fluorination can ensure that the titanium-doped quartz glass has a lower fictive temperature and a smaller slope of the linear thermal expansion coefficient-temperature-curve, because fluorine has an effect on structural relaxation, thereby reducing the unevenness in the linear thermal expansion coefficient distribution of the titanium-doped quartz glass. At the same time, fluorine doping can achieve a lower melting temperature, thereby effectively avoiding defects in the quartz glass caused by thermal effects.

[0038] The beneficial effects of the present invention are:

[0039] The present invention provides a method for preparing ultra-low thermal expansion coefficient fluorinated quartz glass. The method comprises first preparing a TiO2-SiO2 composite material, then fluorinating the resulting TiO2-SiO2 composite material with a fluorine source, pressing the resulting composite material into a compact body, and finally sequentially subjecting the compact body to ceramicization and vitrification. The resulting fluorinated quartz glass has an extremely low thermal expansion coefficient of less than 5×10-8 / K and can be used as a mirror substrate in EUV lithography. The preparation method of the present invention can produce extremely high-purity ultra-low thermal expansion coefficient fluorinated quartz glass, with the total amount of transition metal impurities controlled within 1 ppm. The transition metal impurity content and purity of the raw materials can be increased through purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 This is a flow chart of the preparation process of the ultra-low expansion coefficient fluorinated quartz glass according to Example 1 of the present invention;

[0042] Figure 2 This is an SEM image of the TiO2-SiO2 composite material described in Example 1 of the present invention;

[0043] Figure 3 This is a schematic diagram of the core-shell structure of the TiO2-SiO2 composite material described in Example 1 of the present invention;

[0044] Figure 4This is an SEM image of the TiO2-SiO2 composite material described in Example 2 of the present invention;

[0045] Figure 5 Graph showing the linear thermal expansion coefficient test performance of the ultra-low thermal expansion coefficient fluorinated quartz glass according to Examples 1 and 2 of the present invention;

[0046] Figure 6 and Figure 7 They are respectively SEM images of the TiO2-SiO2 composite material described in Example 3 of the present invention at different magnifications;

[0047] Figure 8 It is the ultra-low expansion coefficient fluorinated quartz glass described in Example 3 of the present invention. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0049] The present invention provides a method for preparing ultra-low expansion coefficient fluorinated quartz glass, comprising the following steps:

[0050] (1) Preparation of TiO2-SiO2 composite materials:

[0051] Silicon source and titanium source are hydrolyzed under catalyst conditions to form TiO2-SiO2 composite material;

[0052] (2) Fluorinated TiO2-SiO2 composite materials:

[0053] fluorinating the TiO2-SiO2 composite material obtained in step (1) with a fluorine source to form a fluorinated TiO2-SiO2 composite material;

[0054] (3) Formation of ultra-low expansion coefficient fluorinated quartz glass:

[0055] The fluorinated TiO2-SiO2 composite material obtained in step (2) is pressed into a dense green body, and then the dense green body is subjected to a vitrification sintering process to obtain an ultra-low expansion coefficient fluorinated quartz glass.

[0056] The TiO2-SiO2 composite material is prepared by using silicate and its derivatives, organosilicon compounds, and silicon salts containing organic acids as silicon sources, and titanate and its derivatives, organotitanium compounds, and titanium salts containing organic acids as titanium sources. The silicon source and the titanium source are mixed and then prepared under the catalytic action of acid or base to generate the TiO2-SiO2 composite material. The TiO2-SiO2 composite material can be a non-porous, microporous, or mesoporous composite material.

[0057] The reaction mechanism for preparing TiO2-SiO2 composite materials is to generate TiO2-SiO2 composite materials by hydrolyzing silicon and titanium organic matter, and to control their morphology, particle size and structure by regulating the reaction temperature, feed rate, stirring rate, pH and water consumption.

[0058] When the TiO2-SiO2 composite material is a non-porous composite material, the fluorine source can be selected as a gaseous fluorine source, and the TiO2-SiO2 composite material is treated with a gas or a gas mixture containing one or more gaseous fluorine sources to form a fluorinated TiO2-SiO2 composite material; in this case, the gas or gas mixture may include other carrier gases in addition to the gaseous fluorine source, such as He, Ar, O2 and N2.

[0059] When the TiO2-SiO2 composite material is a microporous or mesoporous composite material, its fluorine source can be selected from a liquid fluorine source and a gaseous fluorine source; when a liquid fluorine source is selected as the fluoride, the microporous or mesoporous TiO2-SiO2 composite material is immersed in the liquid fluorine source to complete the fluorination process, because the pore structure in the porous TiO2-SiO2 composite material can ensure the fluorination of the liquid fluorine source and retain a large amount of fluoride; at the same time, the porous TiO2-SiO2 composite material can also select a gaseous fluorine source.

[0060] The gaseous fluorine source can be sulfur hexafluoride, silicon tetrafluoride, hydrogen fluoride, or nitrogen fluoride; preferably silicon tetrafluoride, because silicon tetrafluoride does not introduce other elements during the fluorination process, thereby ensuring purity during the fluorination process.

[0061] The liquid fluorine source can be ammonium hexafluorosilicate solution, ammonium bifluoride solution, or hydrofluoric acid solution. Preferably, during the fluorination process, after the liquid fluorine source is fluorinated, the composite material is subjected to secondary fluorination with a gaseous fluorine source. The fluorination temperature of the liquid fluorine source is 20-95°C, and the fluorination temperature of the gaseous fluorine source is 400-1200°C.

[0062] Preferably, a certain amount of chlorine is introduced into the fluorination process of the gaseous fluorine source to reduce the OH - The concentration of the gas fluorine source is 0.5-12 hours for fluorination and chlorination, the flow rate of the fluorination gas is 100 sccm-10000 sccm, and the flow rate of the chlorination gas is 100 sccm-10000 sccm.

[0063] The TiO2-SiO2 composite material was heated at a temperature of 1450-2250℃ and a vacuum degree of 10 -1 -10 -3 Pa is vitrified and sintered. The process can be carried out by hydrogen-oxygen flame sintering on a chemical vapor deposition lathe. As an optional implementation method, fluorine source gas and chlorine gas can be introduced during the sintering process. Example 1

[0064] This embodiment provides a method for preparing ultra-low expansion coefficient fluorinated quartz glass. The process flow is as follows: Figure 1 The specific operations are as follows:

[0065] (1) Preparation of TiO2-SiO2 composite materials:

[0066] 40L of ethyl orthosilicate and 10L of tetrabutyl orthotitanate were dissolved in 20L of anhydrous ethanol and hydrolyzed under the catalysis of 10L of 1mol / L ammonium bifluoride to produce TiO2-SiO2 composite material;

[0067] The average particle size of the TiO2-SiO2 composite material is 200 nm, the morphology is spherical, and the structure is a core-shell structure (such as Figure 2 and Figure 3 As shown); the TiO2-SiO2 composite material is a mesoporous composite material with a pore size of 40nm;

[0068] (2) Fluorinated TiO2-SiO2 composite materials:

[0069] The TiO2-SiO2 composite material obtained in step (1) is subjected to fluorination treatment with a fluorine source to form a fluorinated TiO2-SiO2 composite material; specifically, the TiO2-SiO2 composite material is placed in a 0.1 mol / L ammonium bifluoride solution, soaked for 5 hours, and then silicon tetrafluoride gas and chlorine gas are introduced at 600° C. for 4 hours, with the silicon tetrafluoride gas flow rate being 100 sccm and the chlorine gas flow rate being 1000 sccm;

[0070] (3) Formation of ultra-low expansion coefficient fluorinated quartz glass:

[0071] The fluorinated TiO2-SiO2 composite material obtained in step (2) is pressed into a dense green body, and then the dense green body is subjected to a vitrification sintering process to obtain an ultra-low expansion coefficient fluorinated quartz glass;

[0072] Specifically, with the help of the known "chemical vapor deposition technology (CVD)", the hydrogen-oxygen flame temperature is 1950℃ and the vacuum degree is 10 -2 The glass was sintered at Pa, and silicon tetrafluoride and chlorine were introduced at a flow rate of 100 sccm during the sintering process. Example 2

[0073] This embodiment provides a method for preparing ultra-low expansion coefficient fluorinated quartz glass, and the specific operations are as follows:

[0074] (1) Preparation of TiO2-SiO2 composite materials:

[0075] 40L of ethyl orthosilicate and 8L of tetrabutyl orthotitanate were dissolved in 20L of anhydrous ethanol and hydrolyzed under the catalysis of 10L of 1mol / L hydrofluoric acid to produce TiO2-SiO2 composite material;

[0076] The average particle size of the TiO2-SiO2 composite material is 200 nm and the morphology is spherical (such as Figure 4 As shown), the structure is a core-shell structure; the TiO2-SiO2 composite material is a mesoporous composite material with a pore size of 8-10nm;

[0077] (2) Fluorinated TiO2-SiO2 composite materials:

[0078] The TiO2-SiO2 composite material obtained in step (1) is subjected to fluorination treatment with a fluorine source to form a fluorinated TiO2-SiO2 composite material; specifically, the TiO2-SiO2 composite material is placed in a fluorination furnace at a temperature of 800°C, and silicon tetrafluoride gas and chlorine gas are introduced for 3 hours, with the silicon tetrafluoride gas flow rate being 1000 sccm and the chlorine gas flow rate being 1000 sccm;

[0079] (3) Formation of ultra-low expansion coefficient fluorinated quartz glass:

[0080] The fluorinated TiO2-SiO2 composite material obtained in step (2) is pressed into a dense green body, and then the dense green body is subjected to a vitrification sintering process to obtain an ultra-low expansion coefficient fluorinated quartz glass;

[0081] Specifically, with the help of the known "chemical vapor deposition technology (CVD)", the hydrogen-oxygen flame temperature is 2350℃ and the vacuum degree is 10 -2 Pa was used for vitrification sintering, and silicon tetrafluoride and chlorine were introduced at a flow rate of 100 sccm during the sintering process.

[0082] Thermal expansion coefficient test:

[0083] The ultra-low thermal expansion coefficient fluorinated quartz glass provided in Examples 1 and 2 of the present invention was made into a quartz glass product and subjected to thermal expansion coefficient testing. The thermal expansion coefficient test was conducted using the PPMSDynaCool system of Quantum Design Company of the United States. The test results are shown in FIG. Figure 5In the figure, "1" represents the sample made from the quartz glass obtained in Example 1, and "2" represents the sample made from the quartz glass obtained in Example 2. Example 3

[0084] This embodiment provides a method for preparing ultra-low expansion coefficient fluorinated quartz glass, and the specific operations are as follows:

[0085] (1) Preparation of TiO2-SiO2 composite materials:

[0086] 1L of tetrabutyl orthotitanate was dissolved in 5L of anhydrous ethanol and then poured into 1000g of silica solution suspended in ultrapure water. The solution was hydrolyzed under the catalysis of 200ml of 1mol / L hydrofluoric acid to produce a disordered doped structure TiO2-SiO2 composite material.

[0087] The morphology of the TiO2-SiO2 composite material is as follows Figure 6 and Figure 7 As shown, it can be seen that: in the TiO2-SiO2 composite material, TiO2 is loaded on the surface of SiO2;

[0088] (2) Fluorinated TiO2-SiO2 composite materials:

[0089] The TiO2-SiO2 composite material obtained in step (1) is subjected to fluorination treatment with a fluorine source to form a fluorinated TiO2-SiO2 composite material; specifically, the TiO2-SiO2 composite material is placed in a 0.1 mol / L ammonium bifluoride solution, soaked for 5 hours, and then silicon tetrafluoride gas and chlorine gas are introduced at 600° C. for 4 hours, with the silicon tetrafluoride gas flow rate being 10 sccm and the chlorine gas flow rate being 1000 sccm;

[0090] (3) Formation of ultra-low expansion coefficient fluorinated quartz glass:

[0091] The fluorinated TiO2-SiO2 composite material obtained in step (2) is pressed into a dense green body, and then the dense green body is subjected to a vitrification sintering process to obtain an ultra-low expansion coefficient fluorinated quartz glass;

[0092] Specifically, with the help of the known "electric melting process", the dense body of fluorinated quartz glass material is placed in a vacuum graphite furnace at a temperature of 2150℃ and a vacuum degree of 10 -2 Pa is vitrified and sintered to obtain Figure 8 Ultra-low expansion coefficient fluorinated quartz glass shown.

[0093] The ultra-low expansion coefficient fluorinated quartz glass was tested for transition metal content to obtain a transition metal content report as shown in Table 1.

[0094] Table 1 - Reported transition metal content of the ultra-low expansion coefficient fluorinated quartz

[0095]

[0096] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A method for preparing ultra-low expansion coefficient fluorinated quartz glass, characterized in that: The steps include: (1) Preparation of TiO2-SiO2 composite materials: Silicon source and titanium source are hydrolyzed under catalyst conditions to form TiO2-SiO2 composite material; The silicon source is silicate and its derivatives; The titanium source is titanate and its derivatives; The catalyst is ammonium bifluoride or hydrofluoric acid; (2) Fluorinated TiO2-SiO2 composite materials: fluorinating the TiO2-SiO2 composite material obtained in step (1) with a fluorine source to form a fluorinated TiO2-SiO2 composite material; (3) Formation of ultra-low expansion coefficient fluorinated quartz glass: The fluorinated TiO2-SiO2 composite material obtained in step (2) is pressed into a dense green body, and then the dense green body is subjected to a vitrification sintering process to obtain an ultra-low expansion coefficient fluorinated quartz glass; In step (3), the dense green body is heated at a temperature of 1450-2250°C and a vacuum degree of 10 -1 -10 3 Vitrification sintering was carried out under the conditions of Pa.

2. The method for preparing ultra-low expansion coefficient fluorinated quartz glass according to claim 1, characterized in that: The content of TiO2 in the TiO2-SiO2 composite material is 5-12wt%; The particle size of the TiO2-SiO2 composite material is 10nm-5000nm; The morphology of the TiO2-SiO2 composite material is spherical, hemispherical or angular; The TiO2-SiO2 composite material is a core-shell structure, a sandwich structure, a yolk-shell structure, or a porous network cross-linked structure.

3. The method for preparing ultra-low expansion coefficient fluorinated quartz glass according to claim 1, characterized in that: In step (2), the fluorine source is a gaseous fluorine source or a liquid fluorine source.

4. The method for preparing ultra-low expansion coefficient fluorinated quartz glass according to claim 3, characterized in that: The gaseous fluorine source is one or a mixture of sulfur hexafluoride, silicon tetrafluoride, hydrogen fluoride, and nitrogen fluoride; The liquid fluorine source is one of ammonium hexafluorosilicate solution, ammonium bifluoride solution, and hydrofluoric acid solution, or a mixture of several of them.

5. The method for preparing ultra-low expansion coefficient fluorinated quartz glass according to claim 4, characterized in that: The fluorination temperature of the liquid fluorine source is 20-95°C, and the fluorination temperature of the gaseous fluorine source is 400-1200°C.

6. The method for preparing ultra-low expansion coefficient fluorinated quartz glass according to claim 4, characterized in that: The fluorine content of the fluorinated TiO2-SiO2 composite material is 100ppm-106ppm.

7. Quartz glass prepared according to the preparation method according to any one of claims 1 to 6.

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