A method for preparing a spherical glass structure

Abstract

The present invention provides a method for preparing a spherical glass structure, by adding a sheet-shaped solid gas release agent sheet into a shallow groove, and utilizing the gas released by the solid gas release agent sheet when heated to drive the glass sheet to be hot-formed, thereby forming a wafer-level spherical glass structure. The method has a simple process flow, is convenient to operate, can be accurately quantified, ensures the consistency of the spherical glass structure, and is particularly suitable for large-scale industrial production. At the same time, the present invention can not only accurately control the quality of the solid gas release agent sheet, flexibly adjust the content of the gas release agent powder therein, and prepare a spherical glass structure of a desired size, but also can obtain a spherical glass structure with a roughness similar to or lower than that of the original polished glass sheet. In addition, the preparation method of the spherical glass structure of the present invention has the advantages of low production cost, high reliability, low environmental pollution, etc., and meets the current strict requirements of large-scale production for high efficiency, low consumption, and environmental protection, as well as the high cleanliness standards of ultra-clean rooms.

Description

Technical Field

[0001] The invention belongs to the technical field of MEMS (micro-electro-mechanical system) manufacturing, and relates to a method for preparing a spherical glass structure. Background Art

[0002] Spherical glass structures have important applications in the fields of MEMS device packaging, microfluidics technology, and as gas chambers for containing alkali vapor in atomic devices. At present, the methods for preparing spherical glass structures mainly include self-expansion method and chemical foaming method. Both methods can form the desired spherical structure without changing the original roughness of the glass sheet. Among them, the self-expansion method refers to directly sealing a certain pressure of gas when the silicon wafer and the glass sheet are bonded, and then using the increased gas pressure when the temperature rises to form the glass sheet into a spherical glass structure. However, this process requires a larger cavity to accommodate a sufficient initial amount of gas, which not only increases the requirements for the thickness of the silicon wafer, but also prolongs the time of deep reactive ion etching, thereby increasing the production cost. In addition, this method requires extremely precise control of the cavity size and gas pressure, which increases the process complexity.

[0003] To this end, a new process method, namely the chemical foaming method, was proposed. The chemical foaming method introduces a high-temperature gas release agent that can generate sufficient gas pressure in a shallow cavity to drive the glass sheet to form the desired spherical structure. At the same time, this gas release agent remains stable during the bonding process between the glass sheet and the silicon wafer, and will not decompose and produce gas. It will not be completely decomposed and release a large amount of gas until it is heated to a temperature close to but lower than the softening point of the glass sheet, thereby driving the glass sheet to form a spherical structure. This method not only reduces the requirements for the thickness of the silicon wafer, but also helps to reduce production costs. However, the chemical foaming method also faces some technical difficulties. The gas release agent is usually in the form of a solid powder, which is difficult to meet the strict cleanliness requirements of the clean room. In addition, how to accurately weigh and evenly add a small amount of gas release agent powder to the silicon cavity is also a key problem restricting its large-scale mass production process.

[0004] Therefore, how to provide a new method for preparing spherical glass structures to overcome the limitations of the existing self-expansion method and chemical foaming method, achieve efficient, precise, and large-scale production in an ultra-clean room environment, while reducing costs and simplifying the process has become an important technical problem that technical personnel in this field need to solve urgently.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for preparing a spherical glass structure, which is used to solve the problems in the prior art such as high production cost and great process complexity caused by the self-expansion method, and difficulty in accurately adding the gas release agent powder in the chemical foaming method, difficulty in meeting the cleanliness requirements of the clean room, and difficulty in large-scale mass production.

[0007] To achieve the above object and other related objects, the present invention provides a method for preparing a spherical glass structure, comprising the following steps:

[0008] Providing a substrate, forming a groove array in the substrate, the groove array comprising a plurality of grooves arranged at intervals, the grooves opening from the top surface of the substrate and extending downward to a preset depth;

[0009] placing a solid gas release agent sheet in each of the grooves;

[0010] Providing a glass sheet, bonding the substrate to the glass sheet under vacuum conditions to achieve sealing of the groove array;

[0011] The bonded substrate is heated to a temperature greater than or equal to the softening point of the glass sheet, and kept warm for a certain period of time, until the gas generated by the thermal decomposition of the solid gas release agent sheet heat-forms the softened portion of the glass sheet corresponding to the groove into a spherical structure, and then cooled to room temperature and annealed;

[0012] The substrate is removed to obtain the desired spherical glass structure.

[0013] Optionally, the formation of the solid gas release agent sheet comprises the following steps:

[0014] mixing a gas releasing agent powder with a viscous solution to obtain a mixture slurry;

[0015] Applying the mixture slurry to the surface of a substrate to form a coating with a preset thickness;

[0016] Drying the coating;

[0017] The coating is cut to obtain the solid gas release agent sheet having a predetermined size.

[0018] Optionally, the method further comprises the step of using a vacuum stirring degassing machine to degas the mixture slurry.

[0019] Optionally, the method further comprises the step of separating the solid gas releasing agent sheet from the substrate by using a punching tool.

[0020] Optionally, the gas release agent powder includes any one of calcium carbonate powder, titanium hydride powder and zirconium hydride powder.

[0021] Optionally, the viscous solution includes any one of a sodium silicate solution and a potassium silicate solution.

[0022] Optionally, the mass volume ratio of the gas release agent powder to the viscous solution is 1 g: (2-5) ml.

[0023] Optionally, the substrate includes any one of aluminum foil and copper foil.

[0024] Optionally, the bonding method between the substrate and the glass sheet includes anodic bonding, the voltage range of the anodic bonding is 700-900V, and the temperature range of the anodic bonding is 300-500°C.

[0025] Optionally, the annealing process comprises the following steps:

[0026] Annealing the glass sheet and the substrate after thermal forming, wherein the annealing temperature ranges from 520 to 560° C. and the insulation time ranges from 20 to 40 minutes;

[0027] After the heat preservation is completed, slowly cooling the glass sheet and the substrate to a temperature below the strain point of the glass sheet at a cooling rate of 0.5 to 1.5° C. / min;

[0028] When the temperature drops below the strain point temperature of the glass sheet, the glass sheet and the substrate are naturally cooled to room temperature.

[0029] Optionally, the surface roughness of the spherical glass structure is not higher than the surface roughness of the glass sheet.

[0030] As described above, the present invention provides a method for preparing a spherical glass structure, which comprises the following steps: providing a substrate, forming a groove array in the substrate, the groove array comprising a plurality of grooves arranged at intervals, the groove opening from the top surface of the substrate and extending downward to a preset depth; placing a solid gas release agent sheet in each of the grooves; providing a glass sheet, bonding the substrate and the glass sheet under vacuum conditions to achieve sealing of the groove array; heating the bonded substrate to a temperature greater than or equal to the softening point of the glass sheet, and keeping the temperature for a certain period of time, until the gas generated by the thermal decomposition of the solid gas release agent sheet heat-forms the softened glass sheet corresponding to the groove into a spherical structure, then cooling to room temperature, and performing annealing treatment; removing the substrate to obtain the desired spherical glass structure. The present invention provides a method for preparing a spherical glass structure, by adding a sheet-shaped solid gas release agent sheet in a shallow groove, using the gas released by the solid gas release agent sheet when heated to drive the glass sheet to be heat-formed, thereby forming a wafer-level spherical glass structure. The method has a simple process flow, is easy to operate, can be accurately quantified, ensures the consistency of the spherical glass structure, and is particularly suitable for large-scale industrial production. At the same time, the present invention can not only accurately control the quality of the solid gas release agent sheet, flexibly adjust the content of the gas release agent powder therein, and prepare a spherical glass structure of a desired size, but also can obtain a spherical glass structure with a roughness similar to or lower than that of the original polished glass sheet. In addition, the preparation method of the spherical glass structure of the present invention has the advantages of low production cost, high reliability, and low environmental pollution, which meets the current strict requirements of large-scale production for high efficiency, low consumption, and environmental protection, as well as the high cleanliness standards of clean rooms. In addition, the method is compatible with existing MEMS processes and can be directly integrated into existing semiconductor manufacturing processes without the need for additional complex equipment or processes, further improving production efficiency and compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Shown is a process flow chart of the method for preparing the spherical glass structure of the present invention.

[0032] Figure 2 It is a schematic diagram showing the cross-sectional structure of a substrate provided in the method for preparing a spherical glass structure of the present invention.

[0033] Figure 3 It is a schematic diagram showing the cross-sectional structure after a groove array is formed in the substrate in the method for preparing the spherical glass structure of the present invention.

[0034] Figure 4 It is a schematic diagram of the cross-sectional structure after a solid gas releasing agent sheet is placed in each of the grooves in the method for preparing the spherical glass structure of the present invention.

[0035] Figure 5 It is a schematic diagram of a top view of the structure after a solid gas release agent sheet is placed in each of the grooves in the method for preparing the spherical glass structure of the present invention.

[0036] Figure 6 It is a schematic diagram of the cross-sectional structure after the substrate and the glass sheet are bonded in the method for preparing the spherical glass structure of the present invention.

[0037] Figure 7 It is a schematic diagram showing the cross-sectional structure of the spherical glass structure preparation method of the present invention after the portion of the bonded glass sheet corresponding to the groove is thermally formed into a spherical structure.

[0038] Figure 8 It is a schematic diagram of the cross-sectional structure of the spherical glass structure obtained after removing the substrate in the method for preparing the spherical glass structure of the present invention.

[0039] Fig. 9 It is a schematic diagram of an atomic force microscope showing the outer surface of a single spherical glass structure in the spherical glass structure prepared by the method for preparing a spherical glass structure of the present invention.

[0040] Component number description

[0041] 101 Substrate

[0042] 102 grooves

[0043] 103 Solid gas release agent sheet

[0044] 104 Glass

[0045] 1041 Spherical Structure

[0046] 105 Spherical Glass Structure

[0047] Steps S1 to S5 DETAILED DESCRIPTION

[0048] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0049] See also Figures 1 to 9It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0050] This embodiment provides a method for preparing a spherical glass structure. Figure 1 , shown as a process flow chart of the method, comprising the following steps:

[0051] S1: providing a substrate, forming a groove array in the substrate, wherein the groove array comprises a plurality of grooves arranged at intervals, and the grooves open from the top surface of the substrate and extend downward to a preset depth;

[0052] S2: placing a solid gas release agent sheet in each of the grooves;

[0053] S3: providing a glass sheet, and bonding the substrate to the glass sheet under vacuum conditions to achieve sealing of the groove array;

[0054] S4: heating the bonded substrate to a temperature greater than or equal to the softening point of the glass sheet, and keeping the temperature for a certain period of time, until the gas generated by the thermal decomposition of the solid gas release agent sheet heat-forms the softened portion of the glass sheet corresponding to the groove into a spherical structure, and then cooling to room temperature and performing annealing treatment;

[0055] S5: removing the substrate to obtain the desired spherical glass structure.

[0056] Combine the following Figure 2-Figure 9 The specific technical scheme of each step of the preparation method of the spherical glass structure of the present invention is described in detail.

[0057] First, see Figure 2-Figure 3 , perform the step S1: provide a substrate 101, form a groove array (not shown) in the substrate 101, the groove array includes a plurality of grooves 102 arranged at intervals, the grooves 102 open from the top surface of the substrate 101 and extend downward to a preset depth.

[0058] like Figure 2 As shown, specifically, the substrate 101 includes but is not limited to wafers of different sizes made of different semiconductor materials such as silicon, germanium, silicon germanium, silicon carbide, silicon on insulator, including but not limited to 2 inches, 6 inches, 8 inches, 12 inches, etc. The thickness of the substrate 101 can also be selected according to actual needs. In this embodiment, the substrate 101 takes a silicon wafer as an example, and its thickness can be selected from a standard thickness, such as 725 microns.

[0059] Specifically, Figure 3 As shown, the groove 102 may be formed by photolithography and etching process, mechanical processing process or other suitable process methods. The etching process includes any one of wet etching process, reactive ion etching process and deep reactive ion etching process.

[0060] As an example, the depth of the groove 102 ranges from 200 to 400 micrometers.

[0061] Specifically, the depth of the groove 102 may be 200 micrometers, 250 micrometers, 300 micrometers, 350 micrometers, 400 micrometers, etc., and any other value within this range.

[0062] As an example, the shape of the groove 102 includes a cylindrical shape.

[0063] As an example, the radius of the cylindrical groove 102 is in the range of 1 to 6 mm, and specifically may include but is not limited to radius values ​​such as 1 mm, 2 mm, 3 mm, 4 mm, 5 mm and 6 mm.

[0064] Please see again Figure 4 and Figure 5 , perform the step S2: placing the solid gas releasing agent sheet 103 in each of the grooves 102 .

[0065] As an example, the formation of the solid gas release agent sheet 103 includes the following steps:

[0066] (1) mixing a gas release agent powder with a viscous solution to obtain a mixture slurry;

[0067] (2) applying the mixture slurry to the surface of a substrate to form a coating having a preset thickness;

[0068] (3) drying the coating;

[0069] (4) Cutting the coating to obtain the solid gas release agent sheet 103 having a preset size.

[0070] As an example, the gas release agent powder includes any one of calcium carbonate powder, titanium hydride powder and zirconium hydride powder.

[0071] As an example, the viscous solution includes any one of a sodium silicate solution and a potassium silicate solution. The viscous solution has strong viscosity, which is conducive to uniform mixing with the gas release agent powder.

[0072] As an example, the mass volume ratio of the gas release agent powder to the viscous solution is 1g:(2-5)ml. The mixing ratio (mass volume ratio) of the gas release agent powder to the viscous solution can be flexibly adjusted according to the dispersion effect of the gas release agent powder in the viscous solution and the expected gas release effect, gas release characteristics, etc.

[0073] In this embodiment, the gas releasing agent powder is calcium carbonate powder, and the viscous solution is sodium silicate solution.

[0074] Specifically, in one example, the accurately weighed calcium carbonate powder and the sodium silicate solution are placed in a clean mortar according to a predetermined mixing ratio and ground and mixed for 10 to 15 minutes to ensure that the calcium carbonate powder is evenly dispersed in the sodium silicate solution, thereby obtaining a uniformly mixed mixture slurry.

[0075] In another example, the accurately weighed calcium carbonate powder and the sodium silicate solution can be added to a clean container according to a predetermined mixing ratio. Subsequently, the container is placed in a vacuum stirring deaerator, and the agitator in the vacuum stirring deaerator is used to stir and mix to obtain a uniformly mixed mixture slurry.

[0076] In other examples, the accurately weighed calcium carbonate powder and the sodium silicate solution may be added to a container, such as a centrifuge tube, according to a predetermined mixing ratio. Subsequently, the centrifuge tube is placed in a centrifuge to obtain a uniformly mixed mixture slurry by using centrifugal force.

[0077] As an example, the method further includes the step of using a vacuum stirring degassing machine to degas the mixture slurry.

[0078] Specifically, in one example, a vacuum stirring and degassing machine can be used to degas the mixture slurry that has been uniformly mixed to ensure that no bubbles remain in the mixture slurry. In another example, the unmixed gas release agent powder and the viscous solution can be directly added to a clean container according to a predetermined mixing ratio, and the container is placed in a vacuum stirring and degassing machine. While stirring and mixing, a vacuum operation is performed to remove bubbles in the mixture slurry. That is, the mixing and degassing steps are completed simultaneously in the vacuum stirring and degassing machine, thereby preparing a uniform and bubble-free mixture slurry.

[0079] As an example, the vacuum degree during the degassing treatment is lower than -95 kPa. Under this condition, a good degassing effect can be obtained.

[0080] As an example, the substrate includes any one of aluminum foil and copper foil. No chemical reaction occurs between the substrate and the mixture slurry. In this embodiment, the substrate is preferably aluminum foil.

[0081] As an example, the method of applying the mixture slurry to the surface of the substrate includes spraying, spin coating, dipping, dripping, blade coating, roller coating or other suitable methods. In this embodiment, the mixture slurry is preferably applied to the surface of the substrate by blade coating.

[0082] Specifically, first, the substrate is fixed on the coating machine. The coating machine is provided with a plurality of vacuum adsorption holes at the position where the substrate is carried, and the substrate is fixed through these vacuum adsorption holes to ensure that the substrate remains stable during the coating process. Afterwards, the mixture slurry is poured on the substrate. At the same time, the push rod of the coating machine drives the scraper to move at a certain speed and angle, and evenly scrapes the mixture slurry, so as to form a uniform coating with a uniform thickness on the surface of the substrate.

[0083] Specifically, the thickness of the coating can be precisely controlled by adjusting the distance between the scraper and the substrate. In this embodiment, the specific thickness of the coating can be selected according to actual needs and is not limited here.

[0084] As an example, the drying process includes any one of heating drying, room temperature drying and freeze drying.

[0085] Specifically, in this embodiment, a slicer or other suitable tools may be used to cut the coating to obtain the solid gas releasing agent sheet 103 of a desired size.

[0086] As an example, the method further includes a step of separating the solid gas releasing agent sheet 103 from the substrate by using a punching tool.

[0087] Specifically, in some embodiments, the coating layer may be cut by a slicer first, and then the solid gas release agent sheet 103 may be separated from the substrate by a punching tool. In other embodiments, the solid gas release agent sheet 103 may be separated from the substrate by a punching tool first, and then the solid gas release agent sheet 103 may be cut into a preset size, which may be selected according to actual needs.

[0088] As an example, the solid gas release agent sheet 103 is in the form of a solid sheet. The solid gas release agent sheet 103 can accurately quantify and precisely control the amount of gas released. At the same time, it is also convenient to adjust and cut according to actual needs to meet different dosage release requirements.

[0089] Please see again Figure 6 , perform the step S3: provide a glass sheet 104, and bond the substrate 101 to the glass sheet 104 under vacuum conditions to achieve sealing of the groove array.

[0090] As an example, the glass sheet 104 includes a borosilicate glass sheet.

[0091] Specifically, the borosilicate glass sheets include Pyrex7740 glass sheets, BF33 glass sheets and other suitable borosilicate glass sheets.

[0092] As an example, before bonding, the process steps of cleaning and polishing the substrate 101 and the glass sheet 104 are also included to ensure that the bonding surface meets the bonding roughness requirement.

[0093] Specifically, deionized water or a chemical cleaning agent may be used to clean the bonding surfaces of the substrate 101 and the glass sheet 104 to remove impurities or contaminants on the surfaces.

[0094] As an example, the polishing includes at least one of mechanical polishing and chemical polishing.

[0095] Specifically, in this embodiment, a polishing liquid and / or a polishing pad may be used to polish the surfaces of the substrate 101 and the glass sheet 104 to reduce surface roughness and meet the surface roughness requirements of the bonding process, thereby optimizing the bonding effect.

[0096] As an example, the bonding method of the substrate 101 and the glass sheet 104 includes any one of anodic bonding, fusion bonding or low-temperature direct bonding. In this embodiment, the bonding method of the substrate 101 and the glass sheet 104 is preferably anodic bonding.

[0097] As an example, the voltage range of the anodic bonding is 700-900 V, and the temperature range of the anodic bonding is 300-500° C. In this embodiment, the voltage of the anodic bonding is preferably 800 V, and the temperature of the anodic bonding is preferably 400° C.

[0098] As an example, the solid gas release agent sheet 103 remains stable and does not decompose during the bonding process between the substrate 101 and the glass sheet 104 .

[0099] As an example, the anodic bonding is performed under a vacuum degree lower than 1 Pa to ensure the bonding quality between the substrate 101 and the glass sheet 104 .

[0100] Specifically, different vacuum conditions such as 0.5Pa, 0.1Pa, 0.05Pa, 0.01Pa, 0.005Pa, and 0.001Pa can be selected to achieve anodic bonding between the substrate 101 and the glass sheet 104, optimize the bonding effect, ensure the stable combination of the substrate 101 and the glass sheet 104, and seal the groove array.

[0101] Please see again Figure 7 , perform step S4: heat the bonded substrate 101 to a temperature greater than or equal to the softening point of the glass sheet 104, and keep it warm for a certain period of time, until the gas generated by the thermal decomposition of the solid gas release agent sheet 103 heat-forms the softened portion of the glass sheet 104 corresponding to the groove 102 into a spherical structure 1041, then cool it to room temperature, and perform annealing treatment.

[0102] Specifically, the softening point temperature of the glass sheet 104 in this embodiment refers to the temperature at which the glass sheet 104 changes from a hard and brittle rigid state to a softer and plastic state. Under this temperature condition, the glass sheet 104 can be heated and formed, such as blowing, pressing or stretching, to form different states. In this embodiment, the glass sheet 104 is a borosilicate glass sheet. The softening point temperature of the borosilicate glass sheet is 830°C.

[0103] As an example, the temperature range for heating the substrate 101 is 830-880°C.

[0104] Specifically, the bonded substrate 101 and the glass sheet 104 are placed in a heating furnace for heating, and the heating temperature is controlled at 830-880°C, for example, the temperature can be 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, etc., and is kept warm for 1-10 minutes. The time can be selected as 1 minute, 2 minutes, 3.5 minutes, 4.8 minutes, 5.6 minutes, 6.7 minutes, 7.5 minutes, 8 minutes, 9.2 minutes, 10 minutes, etc. The specific heating temperature and insulation time can be set according to actual needs, but are not limited to this.

[0105] Specifically, under the high temperature heating condition of 830-880°C, the solid gas release agent sheet 103 is decomposed by heat to release gas, so that the pressure inside the groove 102 is greater than the external pressure. This internal and external pressure difference causes the softened glass sheet 104 corresponding to the groove 102 to bulge outward to form a spherical structure 1041. After the molding is completed, the bonded substrate 101 and the glass sheet 104 are taken out of the heating furnace and quickly cooled to room temperature 25°C to stabilize the molding structure and ensure that the spherical structure 1041 of the glass sheet 104 corresponding to the groove 102 after thermal molding will not change due to temperature drop.

[0106] Specifically, during the process of forming the spherical structure 1041 , the groove 102 and the substrate 101 can withstand the pressure difference between the internal air pressure of the groove 102 and the air pressure in the heating furnace.

[0107] Specifically, in this embodiment, by precisely controlling the mass of the solid gas release agent sheet 103, the size of the groove 102 (including parameters such as the opening radius and the groove depth), and the heating temperature, etc., it is possible to precisely control the key dimensions such as the height and the spherical radius of the spherical structure 1041, thereby obtaining the spherical structure 1041 of a preset size and shape.

[0108] As an example, the annealing process includes the following steps:

[0109] (1) performing annealing treatment on the glass sheet 104 and the substrate 101 after thermal forming, wherein the annealing temperature ranges from 520 to 560° C. and the holding time ranges from 20 to 40 minutes;

[0110] (2) After the heat preservation is completed, the glass sheet 104 and the substrate 101 are slowly cooled to a temperature below the strain point of the glass sheet 104 at a cooling rate of 0.5 to 1.5° C. / min;

[0111] (3) When the temperature drops below the strain point temperature of the glass sheet 104, the glass sheet 104 and the substrate 101 are naturally cooled to room temperature.

[0112] Specifically, the glass sheet 104 and the substrate 101 after the thermoforming are annealed in an inert gas atmosphere (such as nitrogen or argon) to eliminate the thermal stress accumulated by the rapid cooling after the thermoforming. In this embodiment, the glass sheet 104 is annealed in an annealing temperature range of 520 to 560° C., so that the internal stress of the glass sheet 104 can be eliminated within about 10 minutes.

[0113] Specifically, in this embodiment, the holding time at the annealing temperature is preferably 30 minutes to ensure that the thermal stress in the glass sheet 104 is fully eliminated and to prevent cracks or defects from occurring.

[0114] Specifically, the strain point temperature of the glass sheet 104 in this embodiment refers to the temperature at which the glass sheet 104 changes from a rigid state to a state where it can undergo significant deformation. Below the strain point temperature, the glass sheet 104 does not undergo viscous flow.

[0115] Specifically, in one example, the glass sheet 104 is a BF33 glass sheet, and the strain point temperature of the BF33 glass sheet is 518° C. After the heat preservation process is completed, the glass sheet 104 and the substrate 101 are preferably slowly cooled to below 518° C. at a cooling rate of 1° C. / min to avoid stress generated inside the glass sheet 104 due to temperature gradient changes. It should be noted that the strain point temperature of the glass sheet 104 is determined by the specific material and composition of the glass sheet 104. The strain point temperature of the glass sheet 104 of different materials is different, which is not specifically limited here.

[0116] Specifically, when the temperature of the glass sheet 104 and the substrate 101 drops below the strain point temperature of the glass sheet 104 or is much lower than the strain point temperature of the glass sheet 104 , the glass sheet 104 and the substrate 101 can be naturally cooled to room temperature.

[0117] Please see again Figure 8 , perform the step S5: remove the substrate 101 to obtain the desired spherical glass structure 105.

[0118] As an example, the method of removing the substrate 101 includes dry etching, wet etching, mechanical grinding or other suitable methods. In this embodiment, preferably, wet etching is used to remove the substrate 101.

[0119] Specifically, in this embodiment, 25% tetramethylammonium hydroxide solution is used to remove the substrate 101 at a temperature of 80°C.

[0120] As an example, after removing the substrate 101 , the method further includes a step of cleaning the spherical glass structure 105 to remove impurities or chemical residues.

[0121] As an example, the surface roughness of the spherical glass structure 105 is not higher than the surface roughness of the glass sheet 104 .

[0122] Specifically, Fig. 9 FIG. 1 is a schematic diagram of an atomic force microscope showing the outer surface of a single spherical glass structure in the spherical glass structure 105 prepared by the method for preparing a spherical glass structure of the present invention. In this embodiment, a 5 μm×5 μm area is selected on the outer surface of a single spherical glass structure to measure its surface roughness.

[0123] Specifically, in this embodiment, the surface roughness of the glass sheet 104 is not higher than 1 nanometer. In this embodiment, the measured surface roughness of the spherical glass structure 105 is 0.622 nanometers, which is significantly smaller than the surface roughness of the glass sheet 104 .

[0124] In summary, the present invention provides a method for preparing a spherical glass structure, which comprises the following steps: providing a substrate, forming a groove array in the substrate, the groove array comprising a plurality of grooves arranged at intervals, the groove opening from the top surface of the substrate and extending downward to a preset depth; placing a solid gas release agent sheet in each of the grooves; providing a glass sheet, bonding the substrate and the glass sheet under vacuum conditions to achieve sealing of the groove array; heating the bonded substrate to a temperature greater than or equal to the softening point of the glass sheet, and keeping the temperature for a certain period of time, until the gas generated by the thermal decomposition of the solid gas release agent sheet heat-forms the softened glass sheet corresponding to the groove into a spherical structure, then cooling to room temperature, and performing annealing treatment; removing the substrate to obtain the desired spherical glass structure. The present invention provides a method for preparing a spherical glass structure, by adding a sheet-shaped solid gas release agent sheet in a shallow groove, using the gas released by the solid gas release agent sheet when heated to drive the glass sheet to be heat-formed, thereby forming a wafer-level spherical glass structure. The method has a simple process flow, convenient operation, accurate quantification, and ensures the consistency of the spherical glass structure, and is particularly suitable for large-scale industrial production. At the same time, the present invention can not only accurately control the quality of the solid gas release agent sheet, flexibly adjust the content of the gas release agent powder therein, and prepare a spherical glass structure of a desired size, but also can obtain a spherical glass structure with a roughness similar to or lower than that of the original polished glass sheet. In addition, the preparation method of the spherical glass structure of the present invention has the advantages of low production cost, high reliability, and low environmental pollution, which meets the current large-scale production requirements for high efficiency, low consumption, and environmental protection, as well as the high cleanliness standards of clean rooms. In addition, the method is compatible with existing MEMS processes and can be directly integrated into existing semiconductor manufacturing processes without the need for additional complex equipment or processes, further improving production efficiency and compatibility. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0125] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a spherical glass structure, characterized in that: The following steps are involved: Providing a substrate, forming a groove array in the substrate, the groove array comprising a plurality of grooves arranged at intervals, the grooves opening from the top surface of the substrate and extending downward to a preset depth; A solid gas release agent sheet is placed in each of the grooves, and the formation of the solid gas release agent sheet includes the following steps: mixing gas release agent powder with a viscous solution to obtain a mixture slurry; applying the mixture slurry to the surface of a substrate to form a coating with a preset thickness; drying the coating; cutting the coating to obtain the solid gas release agent sheet with a preset size; Providing a glass sheet, bonding the substrate to the glass sheet under vacuum conditions to achieve sealing of the groove array; The bonded substrate is heated to a temperature greater than or equal to the softening point of the glass sheet, and kept warm for a certain period of time, until the gas generated by the thermal decomposition of the solid gas release agent sheet heat-forms the softened portion of the glass sheet corresponding to the groove into a spherical structure, and then cooled to room temperature and annealed; The substrate is removed to obtain the desired spherical glass structure.

2. The method for preparing a spherical glass structure according to claim 1, characterized in that: The method also includes the step of using a vacuum stirring degassing machine to degas the mixture slurry.

3. The method for preparing a spherical glass structure according to claim 1, characterized in that: The method further comprises the step of separating the solid gas release agent sheet from the substrate by using a punching tool.

4. The method for preparing a spherical glass structure according to claim 1, characterized in that: The gas release agent powder includes any one of calcium carbonate powder, titanium hydride powder and zirconium hydride powder.

5. The method for preparing a spherical glass structure according to claim 1, characterized in that: The viscous solution includes any one of a sodium silicate solution and a potassium silicate solution.

6. The method for preparing a spherical glass structure according to claim 1, characterized in that: The mass volume ratio of the gas release agent powder to the viscous solution is 1g:(2-5)ml.

7. The method for preparing a spherical glass structure according to claim 1, characterized in that: The substrate includes any one of aluminum foil and copper foil.

8. The method for preparing a spherical glass structure according to claim 1, characterized in that: The bonding method between the substrate and the glass sheet includes anodic bonding, the voltage range of the anodic bonding is 700-900V, and the temperature range of the anodic bonding is 300-500°C.

9. The method for preparing a spherical glass structure according to claim 1, characterized in that: The annealing process comprises the following steps: Annealing the glass sheet and the substrate after thermal forming, wherein the annealing temperature ranges from 520 to 560° C. and the insulation time ranges from 20 to 40 minutes; After the heat preservation is completed, slowly cooling the glass sheet and the substrate to a temperature below the strain point of the glass sheet at a cooling rate of 0.5 to 1.5° C. / min; When the temperature drops below the strain point temperature of the glass sheet, the glass sheet and the substrate are naturally cooled to room temperature.

10. The method for preparing a spherical glass structure according to claim 1, characterized in that: The surface roughness of the spherical glass structure is no greater than the surface roughness of the glass sheet.

Images