Low-expansion glass-ceramics, preparation method and application thereof

Abstract

The present invention discloses a low-expansion glass-ceramic, a preparation method, and applications thereof. The low-expansion glass-ceramic comprises the following components by weight: 56-67% SiO2, 18-27% Al2O3, 3.1-7.0% Li2O, 0.1-0.5% MgO, 0.1-0.9% ZnO, 1.0-2.9% P2O5, 1.0-2.9% TiO2, 1.0-2.9% ZrO2, 0.5-4% Gd2O3, 0.6-1.5% SnO2, and 0.1-0.4% CaF2. The low-expansion glass-ceramic prepared by the present invention has excellent properties such as a low thermal expansion coefficient and good visible light transmittance. The low-expansion glass-ceramic prepared by this method can be used in the field of extreme ultraviolet lithography.

Description

Technical Field

[0001] The present invention relates to the field of special glass materials, and in particular to a low-expansion microcrystalline glass and a preparation method thereof. Background Art

[0002] Low-expansion glass-ceramics not only has ultra-low thermal expansion properties, but also has good light transmittance, and can obtain transparent and colorless glass-ceramics. Therefore, it is widely used in reflectors of large astronomical telescopes, high-temperature observation windows, laser gyroscopes, etc. Due to its extremely low thermal expansion coefficient, high thermal shock resistance, excellent chemical stability and mechanical properties, it plays a very important role in civil and military fields.

[0003] Extreme ultraviolet lithography (EUVL) is an advanced lithography technology for microelectronics that uses extreme ultraviolet rays with a wavelength of 10nm-14nm as the exposure light source. It is an advanced lithography technology for manufacturing microprocessor units (MPUs) and dynamic random access memory (DRAM) chips, and has important applications in fields such as semiconductor manufacturing. With the continuous development of semiconductor technology, the requirements for chip manufacturing precision and integration are becoming increasingly higher. Due to the advantages of high precision and high resolution, EUV lithography plays a key role in the manufacture of smaller and more complex chip structures, making EUV lithography gradually become mainstream. In the future, with the rapid development of 5G, artificial intelligence, the Internet of Things and other fields, the demand for high-performance chips will further promote the development of EUV lithography technology.

[0004] In the EUV lithography system, optical components need to have characteristics such as high precision, high stability and low expansion coefficient to ensure the accuracy and quality of lithography. Low expansion glass for EUV lithography is a special glass material designed specifically for EUV lithography technology. It is a key material in the process of manufacturing high-precision and high-integration semiconductor chips. Low expansion glass for EUV lithography is a special glass with an extremely low thermal expansion coefficient. It is mainly used in the semiconductor manufacturing field to manufacture core key components of EUV lithography machines, such as mirrors and lenses. As a key material in EUV lithography machines, the stability and reliability of the performance of low expansion glass for EUV lithography have an important impact on the lithography effect. Therefore, the demand for low expansion glass in the semiconductor manufacturing industry will continue to grow. Low expansion glass for EUV lithography requires the following special requirements:

[0005] (1) Low thermal expansion coefficient: Low expansion glass for extreme ultraviolet lithography has an extremely low thermal expansion coefficient and can maintain stable size and shape in high temperature and large temperature fluctuation environments; its low thermal expansion characteristics ensure the stability and precision of optical components during the lithography process, thereby improving the resolution and yield of lithography.

[0006] (2) High optical performance: Low expansion glass for EUV lithography has excellent optical properties, including high transmittance, low scattering and low absorption, ensuring high imaging quality during EUV lithography.

[0007] (3) Good mechanical properties: Low expansion glass for extreme ultraviolet lithography has high mechanical strength and hardness, and can withstand the high pressure and high temperature during the lithography process.

[0008] (4) High purity: The impurity content in low-expansion glass materials used in EUV lithography is required to be extremely low to reduce the absorption and scattering of EUV light and improve lithography efficiency.

[0009] Traditional glass-ceramics, due to their excellent optical properties and chemical stability, have been widely studied for use in the manufacture of optical components. However, their thermal expansion properties make it difficult to meet the increasingly demanding technical requirements of extreme ultraviolet lithography. Currently, ultra-low expansion glass materials used in lithography systems fall into two main categories: amorphous ultra-low expansion glass and microcrystalline ultra-low expansion transparent glass-ceramics. However, amorphous ultra-low expansion glass struggles to meet the optical processing requirements of extreme ultraviolet lithography. Research on transparent glass-ceramics has long been a hot topic in the field of specialty glass research, but successful developments of ultra-low expansion glass-ceramics are rare. The key challenge lies in selecting the right components, controlling the crystallization temperature, and crystallization time to ensure uniform, fine, nano-sized crystals are formed during heat treatment.

[0010] Therefore, developing an ultra-low expansion glass-ceramics with a low expansion coefficient suitable for extreme ultraviolet lithography applications has important practical significance and application value. Summary of the Invention

[0011] In order to overcome the problems existing in the prior art, the purpose of the present invention is to provide a low-expansion microcrystalline glass and a preparation method thereof, so as to solve the problem that the existing microcrystalline glass has a high thermal expansion coefficient and cannot meet the high-precision requirements of extreme ultraviolet lithography.

[0012] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0013] A low-expansion glass-ceramic, characterized in that it comprises the following oxides in weight percentage (wt.%):

[0014] SiO2 56-67%

[0015] Al2O3 18-27%

[0016] Li2O 3.1-7%

[0017] MgO 0.1-0.5%

[0018] ZnO 0.1-0.9%

[0019] P2O5 1.0-2.9%

[0020] TiO2 1.0-2.9%

[0021] ZrO2 1.0-2.9%

[0022] Gd2O3 0.5-4%

[0023] SnO2 0.6-1.5%

[0024] CaF2 0.1-0.4%.

[0025] Preferably, the following oxides are prepared in the following amounts by weight:

[0026] SiO2 58-66%

[0027] Al2O3 20-25%

[0028] Li2O 3.5-6%

[0029] MgO 0.1-0.5%

[0030] ZnO 0.1-0.9%

[0031] P2O5 1.0-2.9%

[0032] TiO2 1.0-2.9%

[0033] ZrO2 1.0-2.9%

[0034] Gd2O3 0.5-4%

[0035] SnO2 0.6-1.5%

[0036] CaF2 0.1-0.4%.

[0037] The low-expansion glass-ceramics in the present invention is a low-expansion transparent glass-ceramics with β-quartz solid solution as the main crystal phase, which is prepared by strictly controlled crystallization of glass with Li2O, Al2O3 and SiO2 as the main components.

[0038] SiO2 is the main component that forms the glass skeleton structure and plays a major role in the glass framework. The weight percentage (wt.%) of SiO2 is 56-67. A SiO2 content below 55wt.% makes it difficult to obtain a low-expansion transparent glass-ceramic with a β-quartz solid solution as the main crystalline phase, and also reduces the chemical resistance and mechanical strength of the glass-ceramic. When the SiO2 content exceeds 67wt.%, the high-temperature viscosity of the glass increases, causing the glass melting temperature to be too high.

[0039] Al2O3 is an intermediate oxide of glass. 3+ There are two coordination states: located in tetrahedra or octahedra. When there is sufficient oxygen in the glass, aluminum oxide tetrahedra [AlO4] form, forming a continuous network with silicon oxide tetrahedra. When there is insufficient oxygen in the glass, aluminum oxide octahedra [AlO6] form, which are external to the network and located in the cavities of the silicon oxide network. The weight percentage (wt.%) of Al2O3 is 18-27. Al2O3 content below 18wt.% reduces the chemical and thermal stability of the glass. Al2O3 content above 27wt.% significantly increases the melting temperature of the glass, while also raising the nucleation and crystallization temperatures of the glass-ceramics, resulting in coarse and uneven grain size.

[0040] Li2O is a glassy network oxide. + It can fill cavities in the glass structure and maintain electrical neutrality. The weight percentage (wt.%) of Li2O is 3.1-7.0. A Li2O content below 3.1% increases the melt viscosity of the glass; a Li2O content greater than 7.0% increases the expansion coefficient of the glass-ceramic.

[0041] MgO is a network-external oxide in the glass structure. It improves the mechanical properties of glass-ceramics and reduces the crystallization rate, thereby lowering the glass melting and forming temperatures. This slows the hardening of the glass and improves its forming properties. The weight percentage (wt.%) of MgO is 0.1-0.5. MgO content below 0.1% reduces the mechanical properties of glass-ceramics. MgO content above 0.5% can precipitate crystalline phases such as cordierite and spinel, affecting the performance of glass-ceramics.

[0042] As a flux, ZnO can reduce the high-temperature viscosity of glass, thereby lowering the melting temperature. It also reduces the thermal expansion coefficient of glass-ceramics. The weight percentage (wt.%) of ZnO is 0.1-0.9. A ZnO content below 0.1% fails to reduce the high-temperature viscosity of glass. A ZnO content greater than 0.9% can cause the precipitation of crystalline phases such as cordierite and spinel during crystallization, affecting the performance of glass-ceramics.

[0043] P2O5, TiO2, and ZrO2 can affect the phase separation and crystal phase transformation process of glass and are excellent nucleation inducers. Among them, ZrO2 can delay the transformation of β-quartz solid solution to β-spodumene solid solution, increasing the transparency of microcrystalline glass. ZrO2 only has one hexacoordinate state in glass. It is incompatible with the silicon-oxygen network and exists only in the cavities outside the network, making its structure tend to be compact. The weight percentage (wt.%) of ZrO2 is 1.0-2.9. A ZrO2 content of less than 1.0% will increase the crystallization temperature of the glass; a ZrO2 content of more than 2.9% is likely to produce insoluble substances, causing the microcrystalline glass to lose transparency.

[0044] The weight percentage (wt.%) of P2O5 is 1.0-2.9. A P2O5 content below 1.0% can cause excessive growth of β-quartz solid solution grains, resulting in haze, or insufficient crystallization, leading to an excessively high thermal expansion coefficient for the glass-ceramic product. A P2O5 content greater than 2.9% increases volatility and causes severe streaking in the molten glass. P2O5, introduced from aluminum metaphosphate (Al(PO3)3), lowers the melting temperature of ZrO2 and promotes its melting, facilitating phase separation and forming a three-dimensional interconnected structure.

[0045] TiO2 has a relatively high solubility in glass, is easier to melt, and has a higher crystallization rate than ZrO2. TiO2 is an intermediate oxide in glass. 4+ There are two coordination states in the glass structure, [TiO4] and [TiO6]. At high temperature, Ti 4+ TiO2 exists in a tetracoordinated form and participates in the silicon-oxygen network. At low temperatures, it separates from the silicon-oxygen network along with oxides such as MgO and ZnO, forming crystal nuclei and promoting glass crystallization. The weight percentage (wt.%) of TiO2 is 1.0-2.9. A TiO2 content of less than 1.0% can cause excessive grain growth in the glass-ceramics and increase the thermal expansion coefficient. A TiO2 content greater than 2.9% can cause the glass-ceramics to appear yellow and reduce its transmittance.

[0046] Gd2O3 can lower the crystallization temperature of glass-ceramics, shorten the crystallization time, improve the mechanical strength of the glass-ceramics, and make the crystallized grains uniform. The weight percentage (wt.%) of Gd2O3 is 0.5-4. A Gd2O3 content of less than 0.5% will increase the crystallization time; a Gd2O3 content greater than 4.0% will cause the glass-ceramics to grow too large and increase the thermal expansion coefficient.

[0047] SnO2 is primarily used as a glass clarifier, clearing bubbles in molten glass. It also acts as a variable ion to enhance glass crystallization. The weight percentage (wt.%) of SnO2 is 0.6-1.5%. A SnO2 content less than 0.6% will not achieve the desired clarification effect on the molten glass. A SnO2 content greater than 1.5% will increase the thermal expansion coefficient of the glass-ceramic.

[0048] CaF2 can lower the liquidus temperature of glass and improve the glass-forming ability. The weight percentage (wt.%) of CaF2 is 0.1-0.4. When the CaF2 content is less than 0.1%, the chemical resistance of the microcrystalline glass will be reduced; when the CaF2 content is greater than 0.4%, the thermal expansion coefficient of the microcrystalline glass will increase.

[0049] The low-expansion microcrystalline glass of the present invention does not contain any of B2O3, Na2O, K2O, etc., and does not contain B2O3, so as to reduce the occurrence of phase separation of the glass; at the same time, alkali metal oxides Na2O and K2O are not used, so as to reduce the opacity and poor light transmittance of crystallized microcrystalline glass products.

[0050] The low-expansion microcrystalline glass of the present invention does not contain any of the metal oxides harmful to the environment, such as As2O3, Sb2O5, BaO, PbO, Tl2O, CdO, BeO, V2O5, etc. Even if it contains a very small amount, it is brought in by other glass raw materials.

[0051] The present invention also provides a method for preparing the low-expansion glass-ceramics, comprising the following steps:

[0052] (1) Raw material preparation: weigh the raw materials according to the above chemical composition and raw material requirements, add 5% of the total weight of purified water to the weighed raw materials and mix them evenly to obtain a mixed raw material;

[0053] (2) Melting and forming: The mixed raw materials are placed in a glass melting furnace and smelted at a high temperature of 1550-1650°C for 6-10 hours to fully melt the raw materials and mix them evenly to form a uniform glass liquid; during the glass melting process, a stirring device is used to stir the glass liquid at a stirring speed of 20-40 rpm to fully discharge bubbles and impurities in the glass liquid;

[0054] (3) Clarification and homogenization: The stirred molten glass is passed through a platinum channel for clarification and homogenization to obtain a clarified molten glass;

[0055] (4) Blank forming: The clarified glass liquid is cast into a preheated heat-resistant steel mold to form a glass blank of the desired shape;

[0056] (5) Annealing: Place the glass body in an annealing furnace, heat it to 550-600°C at a rate of 1-3°C / min, keep it at that temperature for 2-4 hours, then cool it to below 300°C at a rate of 0.5-1.5°C / hour, and take it out to cool to room temperature;

[0057] (6) Nucleation and crystallization: The glass blank is then placed in a high-precision annealing furnace, and the sample is heated from room temperature to 630-690°C at a heating rate of 1-3°C / hour, kept warm for 3-5 hours for nucleation, and then continued to be heated to 750-810°C and kept warm for 2-6 hours for crystallization. The nucleation and crystallization process is carried out in a reducing atmosphere. The reducing atmosphere is obtained by placing 3-5% of the sample weight of carbon powder next to the sample. After crystallization treatment, the temperature is cooled to room temperature at a cooling rate of 0.1-0.5°C / min. After processing, low-expansion microcrystalline glass is obtained.

[0058] The low-expansion glass-ceramics of the present invention is an ultra-low-expansion transparent glass-ceramics of the Li2O-Al2O3-SiO2 system with a nano-β-quartz solid solution as the main crystal phase. The grain size of the precipitated β-quartz solid solution phase is 30-60nm, which is one-tenth of the visible light wavelength range (380nm-780nm), and the refractive index of the crystal phase is close to that of glass. Therefore, the transmittance is high in the visible light and infrared light range. At the same time, it has ultra-low expansion performance close to zero, excellent three-dimensional overall uniformity, good processing performance, can be polished to extremely high precision, good film coating performance, excellent chemical resistance and stability, and other characteristics.

[0059] The present invention also provides an application of the low-expansion microcrystalline glass prepared according to the above preparation method in optical precision components, astronomy, extreme ultraviolet lithography or microlithography, such as standard parts for precision measurement technology, as mechanical precision parts of ring laser gyroscopes, coil springs for the watchmaking industry, mask holders, wafer stages or reference plates in extreme ultraviolet lithography or as optical components in extreme ultraviolet lithography, used as reflectors and prisms in extreme ultraviolet lithography, and in particular as substrates for extreme ultraviolet mask blanks or extreme ultraviolet reflectors.

[0060] Compared with the prior art, the low-expansion glass-ceramics provided by the present invention has the following significant advantages:

[0061] (1) The low-expansion glass-ceramics of the present invention does not contain any oxides such as B2O3, Na2O, K2O, etc. that are harmful to the photolithography environment and unfavorable for the extreme ultraviolet photolithography coating process, and has excellent electrical insulation and a stable dielectric constant;

[0062] (2) The thermal expansion coefficient of the low-expansion glass-ceramics of the present invention is extremely low, and its thermal expansion coefficient in the temperature range of 0 to 50°C is (0±1.2)×10 －7 / ℃; has good high temperature resistance and thermal shock resistance;

[0063] (3) The low-expansion glass-ceramics of the present invention has a single ultrafine grain structure. After controlled crystallization, β-quartz solid solution crystallites are precipitated throughout the glass, with a grain size of 30-60 nm. Therefore, apart from a small amount of light absorption, the transmittance of a 5 mm thick low-expansion glass-ceramics is greater than 85%.

[0064] (4) The low-expansion glass-ceramics of the present invention has an ultrafine microcrystalline structure and a uniform and dense texture, so it has excellent mechanical properties, a bending strength greater than 120 MPa, and good wear resistance.

[0065] The low-expansion microcrystalline glass of the present invention optimizes its chemical composition and introduces appropriate amounts of oxides such as Gd2O3 and SnO2, thereby effectively reducing the thermal expansion coefficient of the glass while ensuring the good optical properties and chemical stability of the glass. High-quality low-expansion microcrystalline glass can be prepared, and it also performs well in terms of optical transmittance, chemical stability and mechanical strength. It can well meet the strict requirements of extreme ultraviolet lithography for high-precision optical component materials, provides key material support for the further development of extreme ultraviolet lithography technology, and has broad application prospects and significant economic benefits. DETAILED DESCRIPTION

[0066] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention are described in further detail below.

[0067] The present invention will be further described in detail below with reference to specific embodiments, but this is not intended to limit the present invention. The parameters, measurement methods, and instruments for the low-expansion glass-ceramics of the present invention are as follows:

[0068] (1) The thermal expansion coefficient of glass-ceramics is measured using a horizontal dilatometer and expressed as the average linear expansion coefficient using the method specified in GB / T 7962.16-2010;

[0069] (2) The transmittance of the glass-ceramics was tested according to the method specified in GB / T 7962.12-2010. The transmittance of a 5 mm sample of the glass-ceramics of the present invention was the transmittance at 530 nm.

[0070] (3) The bending strength of glass-ceramics shall be tested in accordance with the method specified in GB / T 6569-2006.

[0071] Table 1 below shows the performance of the embodiments of the present invention and the tests.

[0072] Table 1 Chemical composition (wt.%) and properties of glass-ceramics of the examples

[0073]

[0074]

[0075] The following are the raw materials used in the examples and their requirements:

[0076] Quartz sand (high purity, 150 μm sieve material less than 1%, 45 μm sieve material less than 30%, Fe2O3 content less than 0.01 wt.%), alumina (analytical grade, average particle size 50 μm), lithium carbonate (analytical grade, 400 μm sieve material less than 10%, 63 μm sieve material less than 10%), basic magnesium carbonate (analytical grade), zinc oxide (analytical grade), aluminum metaphosphate (analytical grade), titanium oxide (analytical grade), zirconium oxide (analytical grade), gadolinium oxide (analytical grade), tin oxide (analytical grade, average particle size 60 μm sieve material less than 1%), and calcium fluoride (analytical grade).

[0077] Example 1

[0078] The raw materials are selected according to the components of Example 1 in Table 1, and the Fe content in the raw materials is strictly controlled so that the ingredients meet the glass chemical composition of Table 1. The weighed raw materials are added with 5% of the total weight of pure water and mixed evenly to obtain a mixed raw material. The mixed raw material is then placed in a glass melting furnace and smelted at a high temperature of 1600°C for 8 hours to fully melt the raw materials and mix them evenly to form a uniform glass liquid. During the glass melting process, a stirring device is used to stir the glass liquid at a stirring speed of 30 rpm to fully discharge bubbles and impurities in the glass liquid. The stirred glass liquid is then passed through a platinum channel for clarification and homogenization to obtain a clarified glass liquid. The clarified glass liquid is cast into a preheated heat-resistant steel mold to form the desired shaped glass body; the glass body is placed in an annealing furnace, heated to 580°C at a rate of 2°C / min, kept warm for 3 hours, then cooled to below 300°C at a rate of 1.0°C / hour, taken out and cooled to room temperature; the glass body is then placed in a high-precision annealing furnace, the sample is heated from room temperature to 670°C at a heating rate of 2°C / hour, kept warm for 4 hours for nucleation, and then continued to heat to 780°C and kept warm for 4 hours for crystallization, the nucleation and crystallization processes are carried out in a reducing atmosphere, the reducing atmosphere is obtained by placing 4% of the sample weight of carbon powder next to the sample, after crystallization treatment, the temperature is cooled to room temperature at a rate of 0.3°C / min, and low expansion microcrystalline glass is obtained after processing, and its test properties are shown in Table 1.

[0079] Example 2

[0080] The raw materials are selected according to the components of Example 2 in Table 1, and the Fe content in the raw materials is strictly controlled so that the ingredients meet the glass chemical composition of Table 1. The weighed raw materials are added with 5% of the total weight of pure water and mixed evenly to obtain a mixed raw material. The mixed raw material is then placed in a glass melting furnace and smelted at a high temperature of 1650°C for 6 hours to fully melt the raw materials and mix them evenly to form a uniform glass liquid. During the glass melting process, a stirring device is used to stir the glass liquid at a stirring speed of 40 rpm to fully discharge bubbles and impurities in the glass liquid. The stirred glass liquid is then passed through a platinum channel for clarification and homogenization to obtain a clarified glass liquid. The clarified glass liquid is cast into a preheated heat-resistant steel mold to form the desired shaped glass body; the glass body is placed in an annealing furnace, heated to 600°C at a rate of 3°C / min, kept warm for 2 hours, then cooled to below 300°C at a rate of 1.5°C / hour, taken out and cooled to room temperature; the glass body is then placed in a high-precision annealing furnace, and the sample is heated from room temperature to 630°C at a heating rate of 1°C / hour, kept warm for 5 hours for nucleation, and then continued to heat to 750°C and kept warm for 6 hours for crystallization. The nucleation and crystallization processes are carried out in a reducing atmosphere. The reducing atmosphere is obtained by placing 3% of the sample weight of carbon powder next to the sample. After crystallization treatment, the temperature is cooled to room temperature at a cooling rate of 0.1°C / min. After processing, low-expansion microcrystalline glass is obtained, and its test properties are shown in Table 1.

[0081] Example 3

[0082] The raw materials are selected according to the components of Example 3 in Table 1, and the Fe content in the raw materials is strictly controlled so that the ingredients meet the glass chemical composition of Table 1. The weighed raw materials are added with 5% of the total weight of pure water and mixed evenly to obtain a mixed raw material. The mixed raw material is then placed in a glass melting furnace and smelted at a high temperature of 1550°C for 10 hours to fully melt the raw materials and mix them evenly to form a uniform glass liquid. During the glass melting process, the glass liquid is stirred by a stirring device at a stirring speed of 20 rpm to fully discharge bubbles and impurities in the glass liquid. The stirred glass liquid is then passed through a platinum channel for clarification and homogenization to obtain a clarified glass liquid. The clarified glass liquid is cast into a preheated heat-resistant steel mold to form the desired shaped glass body; the glass body is placed in an annealing furnace, heated to 550°C at a rate of 1°C / min, kept warm for 4 hours, then cooled to below 300°C at a rate of 0.5°C / hour, taken out and cooled to room temperature; the glass body is then placed in a high-precision annealing furnace, and the sample is heated from room temperature to 690°C at a heating rate of 3°C / hour, kept warm for 3 hours for nucleation, and then continued to heat to 810°C and kept warm for 2 hours for crystallization. The nucleation and crystallization processes are carried out in a reducing atmosphere. The reducing atmosphere is obtained by placing 5% of the sample weight of carbon powder next to the sample. After crystallization treatment, the temperature is cooled to room temperature at a rate of 0.5°C / min. After processing, low-expansion microcrystalline glass is obtained, and its test properties are shown in Table 1.

[0083] Example 4

[0084] The raw materials were selected according to the components of Example 4 in Table 1, and the Fe content in the raw materials was strictly controlled so that the ingredients met the glass chemical composition in Table 1. The same process system and test conditions as in Example 1 were used, and the basic properties of the samples are shown in Table 1.

[0085] Example 5

[0086] The raw materials were selected according to the components of Example 5 in Table 1, and the Fe content in the raw materials was strictly controlled so that the ingredients met the glass chemical composition in Table 1. The same melting process system and test conditions as in Example 1 were used. The basic properties of the samples are shown in Table 1.

[0087] From the data obtained in the examples, it can be seen that the low-expansion microcrystalline glass of the present invention does not contain any metal oxides or heavy metal oxides that are harmful to the environment, such as As2O3, Sb2O5, BaO, PbO, Tl2O, CdO, BeO, V2O5, etc., and is green and environmentally friendly; and by introducing an appropriate amount of oxides such as Gd2O3 and SnO2, the thermal expansion coefficient of the glass is effectively reduced, while ensuring the good optical properties and chemical stability of the glass. High-quality low-expansion microcrystalline glass can be prepared, and it also performs well in terms of optical transmittance, chemical stability and mechanical strength. It can well meet the strict requirements of extreme ultraviolet lithography for high-precision optical component materials, and provides key material support for the further development of extreme ultraviolet lithography technology. It has broad application prospects and significant economic benefits.

[0088] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art may make any modifications, equivalent substitutions, or improvements to the present invention within the spirit and scope of protection of the present invention, and such modifications or equivalent substitutions are deemed to fall within the scope of protection of the present invention.

Claims

1. A method for preparing low-expansion glass-ceramics, characterized in that: The following steps are involved: (1) Raw material preparation: weigh the raw materials according to the chemical composition and raw material requirements, add 5% of the total weight of purified water to the weighed raw materials and mix them evenly to obtain a mixed raw material; (2) Melting and forming: The mixed raw materials are placed in a glass melting furnace and smelted at a high temperature of 1600°C for 8 hours to fully melt and mix the raw materials to form a uniform glass liquid; during the glass melting process, the glass liquid is stirred by a stirring device at a stirring speed of 30 revolutions per minute to fully discharge bubbles and impurities in the glass liquid; (3) Clarification and homogenization: The stirred molten glass is passed through a platinum channel for clarification and homogenization to obtain a clarified molten glass; (4) Blank forming: The clarified glass liquid is cast into a preheated heat-resistant steel mold to form a glass blank of the desired shape; (5) Annealing: Place the glass body in an annealing furnace, heat it to 580°C at a rate of 2°C / min, keep it at that temperature for 3 hours, then cool it to below 300°C at a rate of 1.0°C / hour, and take it out and cool it to room temperature; (6) Nucleation and crystallization: The glass blank is then placed in a high-precision annealing furnace, and the sample is heated from room temperature to 670°C at a heating rate of 2°C / hour, and kept at this temperature for 4 hours for nucleation. The temperature is then further raised to 780°C and kept at this temperature for 4 hours for crystallization. The nucleation and crystallization processes are carried out in a reducing atmosphere. After the crystallization treatment, the temperature is cooled to room temperature at a cooling rate of 0.3°C / min. After processing, low-expansion micro-ceramics are obtained; The reducing atmosphere is obtained by placing carbon powder of 3-5% of the sample weight next to the sample; After controlled crystallization of the low-expansion glass-ceramics, the grain size is 30-60 nm, and the transmittance of 5 mm thick low-expansion glass-ceramics is greater than 85%; The low-expansion glass-ceramics is prepared from the following oxides in percentage by mass:

2. The method for preparing low-expansion glass-ceramics according to claim 1, wherein: The low-expansion glass-ceramics does not contain any of B2O3, Na2O, and K2O.

3. The method for preparing low-expansion glass-ceramics according to claim 1 or 2, characterized in that: It does not contain any of the metal oxides harmful to the environment, such as As2O3, Sb2O5, BaO, PbO, Tl2O, CdO, BeO, and V2O5.

4. Application of the low-expansion glass-ceramics prepared by the preparation method according to any one of claims 1 to 3 in optical precision components, astronomy, extreme ultraviolet lithography or microlithography.

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