Alkali metal atom gas chamber and its preparation method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-12
- Publication Date
- 2026-08-14
AI Technical Summary
[0101]由以上技术方案可以看出，本公开具有以下有益效果：
Smart Images
Figure CN122562293A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of quantum sensing technology, specifically relating to an alkali metal atom gas chamber and its preparation method. Background Technology
[0002] Atomic gas cells are the core component of quantum sensing technology, playing a decisive role in device performance. Currently, devices based on atomic gas cells, such as atomic clocks, atomic magnetometers, and atomic gyroscopes, leverage the accuracy of atomic spectra to achieve high-precision, high-sensitivity measurements, and are widely used in military defense, aerospace, information and communication, and biomedical fields. Miniaturization of atomic gas cells helps reduce device power consumption, increase device integration, and improve device portability, making it the most effective solution for the increasing complexity of future applications.
[0003] Currently, the preparation processes for atomic gas cells include glass blowing, machining, glass etching, and anodic bonding technology. However, these processes suffer from problems such as high cost, low efficiency, difficulty in shape control, and difficulty in demolding, making them unsuitable for industrial production.
[0004] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide an alkali metal atom gas chamber and its preparation method.
[0005] Public content
[0006] The purpose of this disclosure is to provide an alkali metal atomic gas cell and its preparation method, which can batch prepare atomic gas cells with multiple light transmission directions and controllable size, and solve the problems of high process cost, low efficiency, difficulty in shape control or demolding in existing preparation processes.
[0007] To achieve the above objectives, a specific embodiment of this disclosure provides a method for preparing alkali metal atomic gas chambers. The method includes: providing a mold, the mold including a first surface and a second surface disposed opposite to each other, the mold having a plurality of closed grooves extending from the first surface to the second surface; filling the closed grooves with molten glass using a hot reflow process, causing the molten glass to overflow outside the closed grooves and cover the first surface; obtaining a composite sheet after the molten glass cools, the composite sheet including a nested mold and solid glass; planarizing the surface of the solid glass away from the mold; removing the mold from the composite sheet using an etching process to obtain a glass substrate, the glass substrate having a plurality of atomic gas chamber shells, the shape of the atomic gas chamber shells corresponding to the closed grooves, having cavities formed therein, and one end face of the atomic gas chamber shells not being closed; filling the cavity of the atomic gas chamber shells with alkali metal atoms; providing a silicon wafer, aligning the silicon wafer with the unclosed end face of the atomic gas chamber shells, and performing anodic bonding to achieve sealing of the atomic gas chambers; dicing to obtain multiple independent alkali metal atomic gas chambers.
[0008] In one or more embodiments of this disclosure, the mold includes a silicon-based mold or a high-temperature metal mold.
[0009] In one or more embodiments of this disclosure, the closed groove includes an outer ring sidewall and at least one inner ring sidewall, wherein the cross-sectional shape of the inner ring sidewall along the direction perpendicular to the extension is circular, semi-circular, or polygonal.
[0010] In one or more embodiments of this disclosure, the closed groove includes an outer ring sidewall and two spaced-apart inner ring sidewalls located within the outer ring sidewall. The groove depth between the inner ring sidewalls is less than the depth of the remaining area of the closed groove. The cross-sectional shape of the inner ring sidewalls along the direction perpendicular to the extension is circular, semi-circular, or polygonal, so that the mold forms two spaced-apart columnar structures in the closed groove.
[0011] In one or more embodiments of this disclosure, molten glass is filled into the closed groove using a hot reflow process, causing the molten glass to overflow outside the closed groove. After the molten glass cools, a composite sheet is obtained. The composite sheet includes a nested mold and solid glass. The process includes: providing a glass sheet and placing it on a first surface of the mold; clamping the mold and the glass sheet using a clamping tool; placing the mold and the glass sheet in a heating furnace and heating them at a set temperature and pressure for a preset time to form molten glass that fills the closed groove; turning off the heating furnace and obtaining the composite sheet after the molten glass and the mold cool to room temperature.
[0012] In one or more embodiments of this disclosure, the preparation method further includes: after removing the mold in the composite sheet by an etching process to obtain a glass substrate, annealing the glass substrate to remove stress.
[0013] In one or more embodiments of this disclosure, annealing the glass substrate includes: placing the glass substrate in an annealing furnace and annealing it at a temperature of 500-600°C for 30-45 minutes, and then cooling it to room temperature.
[0014] In one or more embodiments of this disclosure, a mold is provided, comprising: providing a silicon wafer; cleaning and drying the substrate silicon wafer using a standard cleaning process; spin-coating photoresist on the silicon wafer; preparing a photoresist mask using a photolithography process; based on the photoresist mask, preparing closed trenches on the silicon wafer using a deep silicon etching process, and obtaining a columnar structure on the silicon wafer; removing residual photoresist on the silicon wafer; cleaning the silicon wafer using a standard cleaning process to obtain a silicon-based mold.
[0015] In one or more embodiments of this disclosure, removing the mold from the composite sheet to obtain a glass substrate based on an etching process includes: preparing a KOH solution with a mass fraction of 25% to 30% and heating the KOH solution to 70°C; immersing the composite sheet in the KOH solution until the silicon-based mold separates from the glass substrate.
[0016] In one or more embodiments of this disclosure, filling the cavity of the atomic gas chamber shell with alkali metal atoms includes: preparing an alkali metal vapor reflector, the alkali metal vapor reflector having a plurality of through holes; placing an alkali metal evaporation source, the alkali metal vapor reflector and the glass substrate in an evaporation device from bottom to top, and aligning the positions of the through holes with the positions of the cavity; and filling the cavity with alkali metal by a direct alkali metal vapor deposition method.
[0017] In one or more embodiments of this disclosure, the conditions for anodic bonding include: a bonding environment of nitrogen or inert gas atmosphere with a pressure range of 100 to 1520 torr, a bonding temperature of 250 to 400°C, and a bonding voltage of 1000 to 1500 V.
[0018] Another aspect of this disclosure provides an alkali metal atom gas chamber, which includes an atom gas chamber shell and a silicon wafer. One end face of the atom gas chamber shell is not closed and a cavity is formed therein. The silicon wafer is connected to the unclosed end face of the atom gas chamber shell by anodic bonding to form a sealed atom gas chamber, which is filled with alkali metal atoms.
[0019] In one or more embodiments of this disclosure, the atomic gas chamber housing further includes a partition located within the cavity, the partition dividing the atomic gas chamber into two interconnected sub-chambers, the sub-chambers being filled with alkali metal atoms.
[0020] Compared with the prior art, the alkali metal atom gas cell and its preparation method disclosed in this invention have a simple preparation process. The glass substrate with several atom gas cell shells is prepared by using a glass reflow process combined with a mold, which greatly improves the shape accuracy of the atom gas cell. Atom gas cells with multiple light transmission directions and controllable size and diverse shapes can be obtained. This invention can also realize the batch preparation of atom gas cells, which greatly improves the preparation efficiency of atom gas cells. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 This is a flowchart of a method for preparing an alkali metal atom gas chamber according to an embodiment of this disclosure;
[0023] Figure 2 This is a cross-sectional view of a mold according to an embodiment of the present disclosure;
[0024] Figure 3 This is a perspective view of the mold in another embodiment of the present disclosure;
[0025] Figure 4 for Figure 3 Top view of the mold shown;
[0026] Figure 5 for Figure 3 A cross-sectional view of the mold shown;
[0027] Figure 6 This is a schematic cross-sectional view of various closed trenches along the extension direction in one embodiment of the present disclosure;
[0028] Figure 7 This is a top view of the mold in another embodiment of the present disclosure;
[0029] Figure 8 for Figure 7 A cross-sectional view of the mold shown;
[0030] Figure 9 This is a schematic diagram showing the positional relationship between the glass sheet and the mold in another embodiment of this disclosure;
[0031] Figure 10 This is a cross-sectional view of the composite sheet in another embodiment of this disclosure;
[0032] Figure 11 This is a cross-sectional view of a glass substrate according to another embodiment of the present disclosure;
[0033] Figure 12 This is a schematic diagram showing the positional relationship between the alkali metal evaporation source, the alkali metal vapor reflector, and the glass substrate in another embodiment of this disclosure;
[0034] Figure 13 This is a cross-sectional view of a composite wafer according to an embodiment of the present disclosure;
[0035] Figure 14 This is a cross-sectional view of an alkali metal atom gas chamber in one embodiment of this disclosure;
[0036] Figure 15 This is a cross-sectional view of an alkali metal atom gas chamber in yet another embodiment of this disclosure. Detailed Implementation
[0037] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.
[0038] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.
[0039] It should be noted that when an element is described as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. In the embodiments shown in this disclosure, directional representations such as up, down, left, right, front, and back are relative and are used to explain the relative structure and movement of different components in this disclosure. These representations are appropriate when the components are in the positions shown in the figures. However, if the description of the component positions changes, then these representations are considered to change accordingly.
[0040] As mentioned in the background section, traditional glass-blowing and machining methods produce atomic gas cells that are large in size, making it difficult to effectively reduce the size of the gas cells and hindering mass production, resulting in low efficiency and high cost. Currently, alkali metal atomic gas cells based on MEMS technology are widely used in chip atomic clocks, miniature magnetometers, etc. However, the silicon anode bonding used in this method means that the miniaturized atomic gas cell has only one direction of light transmission, limiting the magnetometer to a single-beam pump-probe scheme and restricting device performance. Therefore, fabricating miniaturized atomic gas cells with two or more optical windows is of great significance for improving the performance of atomic magnetometers.
[0041] Existing technologies have enabled the mass production of spherical glass atomic gas cells. However, the multiple reflections of the light beam within these cells generate stray light, reducing the polarization obtained during the optical pumping process and weakening the device's response. A method based on etching a glass substrate to form through-holes and bonding silicon wafers on both sides can fabricate MEMS atomic gas cells that are transparent in two directions, but the glass etching process is costly and inefficient. In 2022, Yu Mingzhi et al. used laser drilling to fabricate cavities on a glass substrate and combined this with anodic bonding technology to achieve the fabrication of atomic gas cells that are transparent in three directions. Cavities were fabricated on a glass substrate using laser-induced etching technology, and then UV-cured adhesives were used to form atomic gas cells that are transparent in three directions. However, the UV-cured adhesives have low strength, making it difficult to guarantee long-term lifespan. Furthermore, existing fabrication processes also suffer from difficulties in shape control and demolding.
[0042] Based on the above understanding, this disclosure provides a method for preparing alkali metal atomic gas cells. The technical idea is to combine glass reflow process and MEMS process to batch prepare atomic gas cells with multiple light transmission directions and controllable size.
[0043] Please refer to Figure 1 As shown, the preparation method provided in this disclosure specifically includes:
[0044] S1 provides molds.
[0045] Please combine Figure 2 As shown, the mold 10 includes a first surface and a second surface arranged opposite to each other, and the mold has a plurality of closed grooves 11 that are spaced apart and extend from the first surface to the second surface.
[0046] Please combine Figures 3-5 In the example shown, the closed groove 11 includes an outer ring sidewall 111 and an inner ring sidewall 112, and the cross-sectional shape of the outer ring sidewall 111 and the inner ring sidewall 112 along the direction perpendicular to the extension is circular. The size of the outer ring sidewall 111 is larger than the size of the inner ring sidewall 112, and the inner ring sidewall 112 is located inside the outer ring sidewall 111.
[0047] It is understandable that the depth of the closed groove 11 is less than the overall thickness of the mold 10. The closed groove 11 is formed between the outer ring sidewall 111 and the inner ring sidewall 112. The cross section of the closed groove 11 along the direction perpendicular to the extension of the closed groove 11 is a ring. Under the action of the inner ring sidewall 112, the mold 10 forms a columnar structure 12.
[0048] Please combine Figure 6As shown, in other alternative embodiments, the cross-sectional shape of the inner ring sidewall 112 along the direction perpendicular to the extension can also be a polygon such as a semicircle, rectangle, regular hexagon, or isosceles trapezoid. Similarly, the cross-section of the closed groove 11 along the direction perpendicular to the extension corresponds to different shapes of rings, and the cross-section of the columnar structure 12 follows the cross-sectional shape of the inner ring sidewall.
[0049] In other alternative embodiments, the closed groove 11 may include an outer ring sidewall 111 and a plurality of inner ring sidewalls 112 located within the outer ring sidewall.
[0050] Please combine Figure 7 and Figure 8 As shown, in an alternative embodiment, the closed groove 11 includes an outer ring sidewall 111 and two spaced-apart inner ring sidewalls (including a first inner ring sidewall 1121 and a second inner ring sidewall 1122) located within the outer ring sidewall 111. The groove depth between the first inner ring sidewall 1121 and the second inner ring sidewall 1122 is less than the depth of the remaining area of the closed groove. The cross-sectional shape of the inner ring sidewall 112 along the direction perpendicular to the extension can be circular, semi-circular, or polygonal, so that the mold forms two spaced-apart columnar structures (including a first columnar structure 121 and a second columnar structure 122) in the closed groove 11. The purpose of this arrangement is to form two connected sub-chambers inside the subsequently produced atomic gas chamber, the shapes of which correspond to the shapes of the first columnar structure 121 and the second columnar structure 122, respectively.
[0051] It is understood that the closed groove 11 is connected between the outer ring sidewall 111 and the inner ring sidewall 112. Similarly, the cross-sectional shapes of the outer ring sidewall 111, the first inner ring sidewall 1121, and the second inner ring sidewall 1122 along the direction perpendicular to the extension can also be polygons such as rectangles, regular hexagons, and isosceles trapezoids, and the cross-sections of the first columnar structure 121 and the second columnar structure 122 follow the cross-sectional shape of the inner ring sidewall. Preferably, the cross-sectional shapes and dimensions of the first inner ring sidewall 1121 and the second inner ring sidewall 1122 along the direction perpendicular to the extension are the same.
[0052] Furthermore, the mold can be a silicon-based mold or a high-temperature metal mold, wherein the material of the high-temperature metal mold can be an iron-based high-temperature alloy, a nickel-based high-temperature alloy, a cobalt-based high-temperature alloy, molybdenum, tungsten, etc.
[0053] When the mold is a silicon-based mold, step S1 specifically includes:
[0054] S101 provides silicon wafers, which are cleaned and dried using a standard cleaning process.
[0055] S102, photoresist is spin-coated onto a silicon wafer, and a patterned photoresist mask is fabricated using a photolithography process. It is understood that the pattern of the photoresist mask corresponds to the shape of the target closed trench.
[0056] S103, based on a photoresist mask, uses deep silicon etching to create closed trenches on a silicon wafer, and obtains the corresponding columnar structure on the silicon wafer.
[0057] S104, remove residual photoresist from the silicon wafer, and clean the silicon wafer using a standard cleaning process to obtain a silicon-based mold.
[0058] When the mold is a high-temperature metal mold, common machining methods can be used to prepare the mold.
[0059] S2, based on the hot reflow process, molten glass is filled into the closed groove 11, so that the molten glass overflows outside the closed groove 11 and covers the first surface. After the molten glass cools, a composite sheet is obtained. The composite sheet includes a nested mold 10 and solid glass.
[0060] Step S2 specifically includes:
[0061] Please refer to Figure 9 As shown, a glass sheet 20 is provided and placed on the first surface of the mold 10. The mold and the glass sheet are clamped by a clamping tool. The glass sheet can be Pyrex glass or BF33 glass.
[0062] The mold 10 and the glass sheet 20 are placed in a heating furnace and heated at a set temperature of 900~1000℃ and a set pressure (1~1.2 atmospheres) for a preset time (about 2~3 hours) to make the glass sheet 20 form molten glass and fully fill the closed groove 11. At the same time, the excess molten glass covers the first surface of the mold 10 and has a certain thickness.
[0063] After the heating furnace is turned off and the molten glass and mold are cooled to room temperature, a composite sheet is obtained.
[0064] S3, planarization treatment of the solid glass surface away from the mold.
[0065] The solid glass is planarized on the side away from mold 10 using a chemical mechanical polishing process, resulting in... Figure 10 The composite sheet shown here includes a mold 10 and a glass substrate 21 nested therewith.
[0066] S4, the mold 10 in the composite sheet is removed by the etching process to obtain the glass substrate 21. The glass substrate 21 has a plurality of atomic gas chamber shells 212. The shape of the atomic gas chamber shells 212 corresponds to the closed groove 11. A cavity 213 is formed inside the cavity, and one end face of the atomic gas chamber shells 212 is not closed.
[0067] Please refer to Figure 11 As shown, the glass substrate 21 includes an integrally formed substrate 211 and a plurality of spaced atomic gas chamber shells 212 that protrude from the surface of the substrate. It can be understood that the sidewalls of the atomic gas chamber shells 212 are closed and just form a cavity with one end open.
[0068] If the cross-sectional shape of the closed groove perpendicular to the extension direction is circular, the atomic gas chamber shell 212 is an open-top cylinder, and the cavity is also cylindrical. If the cross-sectional shape of the closed groove perpendicular to the extension direction is square, the atomic gas chamber shell 212 is an open-faced regular hexahedron, and the cavity is also regular hexahedron. And so on, the shape and dimensions of the atomic gas chamber shell 212 correspond exactly to the shape and dimensions of the closed groove.
[0069] Furthermore, if the mold is a silicon-based mold, the mold 10 in the composite sheet is removed by a wet etching process to obtain a glass substrate 21. For example, a KOH solution with a mass fraction of 25% to 30% is prepared and heated to 70°C. The composite sheet is then immersed in the KOH solution until the silicon-based mold separates from the glass substrate.
[0070] If mold 10 is a high-temperature metal mold, then a metal etching solution is used to remove the mold from the composite sheet to obtain glass substrate 21. It is understood that the use of metal etching solution to remove metal is well known in the prior art, and therefore will not be described in detail here. Any known or unknown metal etching process may be used without restriction.
[0071] S5, alkali metal atoms are filled into the cavity of the atomic gas chamber shell.
[0072] Please combine Figure 12 As shown, step S5 specifically includes:
[0073] An alkali metal vapor reflector 30 is prepared, and the alkali metal vapor reflector has several through holes 31.
[0074] An alkali metal evaporation source 40, an alkali metal vapor reflector 30, and a glass substrate 21 are placed sequentially from bottom to top inside the evaporation device, with the position of the through hole 31 corresponding to the position of the cavity. Alkali metal is then filled into the cavity by a direct alkali metal vapor deposition method. The alkali metal can be rubidium, potassium, or cesium.
[0075] Furthermore, the chamber vacuum level of the evaporation device is better than 10. -3 Pa, water and oxygen content below 1ppm, evaporation temperature set at 80~90 degrees Celsius, evaporation time 10~20 minutes.
[0076] S6 provides a silicon wafer 50, and after aligning the silicon wafer 50 with the unsealed end face of the atomic gas chamber shell, performs anodic bonding to achieve sealing of the atomic gas chamber.
[0077] The conditions for anodic bonding include: a bonding environment of nitrogen or an inert gas atmosphere with a pressure range of 100–1520 torr, a bonding temperature of 250–400°C, and a bonding voltage of 1000–1500 V. The inert gas can be nitrogen, helium, or neon. It is understood that during anodic bonding, nitrogen or an inert gas is introduced into the atomic chamber as a buffer gas.
[0078] Please refer to Figure 13 As shown, after anodic bonding, a composite wafer 100 is obtained. The composite wafer 100 consists of a silicon wafer 50, a glass substrate 21, and alkali metal atoms and buffer gas enclosed between the two. An array of atomic gas cells is arranged at intervals on the composite wafer 100.
[0079] S7, dicing, to obtain multiple independent alkali metal atom gas chambers.
[0080] Please refer to Figure 14 As shown, the entire composite wafer 100 is diced using a single atomic gas cell as a unit to form multiple independent atomic gas cells. The dicing positions are located between the shells of two adjacent atomic gas cells.
[0081] Furthermore, the preparation method in this disclosure also includes: after removing the mold in the composite sheet by an etching process to obtain a glass substrate, annealing the glass substrate to remove stress.
[0082] Specifically, this involves placing the glass substrate in an annealing furnace and annealing it at 500-600°C for 30-45 minutes, then cooling it to room temperature.
[0083] Please refer to Figure 14 As shown, this disclosure also provides an alkali metal atom gas chamber, including an atom gas chamber shell 212 and a silicon wafer 50. One end face of the atom gas chamber shell 212 is not closed and a cavity is formed therein. The silicon wafer 50 is connected to the unclosed end face of the atom gas chamber shell 212 by anodic bonding to form a sealed atom gas chamber. The atom gas chamber is filled with alkali metal atoms and a buffer gas.
[0084] Please refer to Figure 15 As shown, in another alternative embodiment, the atomic gas chamber housing 212 further includes a partition 213 located within its cavity, the partition 213 dividing the atomic gas chamber into two interconnected sub-chambers, the sub-chambers being filled with alkali metal atoms and a buffer gas.
[0085] Combining the above and Figure 7 and Figure 8As shown in the mold shape, when the closed groove 11 includes an outer ring sidewall 111 and two spaced-apart inner ring sidewalls 112 located within the outer ring sidewall, a dual-chamber alkali metal atom gas chamber can be fabricated. The partition 213 is formed by molten glass filling the groove between the two inner ring sidewalls 112. Therefore, the atom gas chamber shell and the partition are integrally formed structures. The atom gas chamber shell has a first end face and sidewalls, and the partition has four sides. The first side of the partition is connected to the first end face of the atom gas chamber shell, the second and third side of the partition are connected to the sidewalls of the atom gas chamber shell, and the fourth side of the partition faces the silicon wafer but is not connected to the silicon wafer, thus dividing the atom gas chamber into two interconnected sub-chambers.
[0086] The present disclosure will be further described below with reference to specific embodiments.
[0087] Example 1:
[0088] The preparation method of the alkali metal atom gas cell in this embodiment is carried out according to the following steps:
[0089] (1) Preparation of silicon-based molds:
[0090] a. Select a silicon wafer with a thickness of 3mm, clean it using the standard cleaning process, and then dry it.
[0091] b. After spin-coating a 20μm thick photoresist onto the silicon wafer, a ring pattern is prepared using photolithography.
[0092] c. Using photoresist as a mask, a ring-shaped groove with a depth of 2mm is prepared on the silicon wafer using a deep silicon etching process, while a columnar structure is obtained in the silicon-based mold.
[0093] d. Remove residual photoresist from the silicon wafer using the organic solvent acetone, then clean the silicon wafer using standard processes to form... Figure 3 The silicon-based mold shown.
[0094] (2) Select a glass sheet with a thickness of 4 mm, place it on the silicon-based mold obtained in step (1), and clamp it with a high-temperature resistant clamping tool. Place the obtained silicon-glass sheet in a heating furnace, set the temperature to 1000℃ and the pressure to 1 atmosphere. After reaching the set temperature and pressure, maintain it for 2 hours, then turn off the heating furnace, cool it to room temperature, and then take out the composite sheet (composed of a silicon-based mold and a glass sheet with a gas chamber as the main structure).
[0095] (3) The side of the cured glass away from the silicon-based mold is flattened by chemical mechanical polishing process.
[0096] (4) Prepare a 25% KOH solution by mass and heat it to 70 degrees Celsius. Then immerse the composite sheet in the solution until the silicon mold separates from the glass sheet with the main structure of the gas chamber, thus obtaining a glass substrate. Anneal the obtained glass substrate in an annealing furnace at 600 degrees Celsius for 30-45 minutes, and then slowly cool it to room temperature.
[0097] (5) A through-hole structure corresponding to the ring pattern in step (1) is prepared on a 300μm silicon wafer using photolithography and etching processes, and used as an alkali metal vapor reflector.
[0098] (6) Alkali metal filling of the atomic gas chamber is achieved using the alkali metal direct vapor deposition method. The alkali metal evaporation source, alkali metal vapor reflector, and glass plate with the main structure of the gas chamber are placed from bottom to top inside the evaporation device. The chamber vacuum degree of the evaporation device is better than 10. -3 Pa, with an oxygen content of less than 1 ppm. This embodiment uses... 87 Rb was used as the alkali metal evaporation source. The evaporation temperature was set to 80-90 degrees Celsius, and the evaporation time was 10 minutes, ultimately resulting in a filled metal. 87 Rb glass substrate.
[0099] (7) Place the alkali metal-filled glass substrate on a 500μm silicon wafer and use an anodic bonding process in a 200 torr nitrogen atmosphere. Control the bonding temperature at 250~400 degrees Celsius, the bonding voltage at 1000~1500V, and set a suitable bonding current. When the loop current drops to less than one-tenth of the peak current, the bonding is completed. 87 Rb atom gas chamber array.
[0100] (8) A single alkali metal atom gas cell is obtained by dicing process.
[0101] As can be seen from the above technical solutions, this disclosure has the following beneficial effects:
[0102] This disclosure combines glass reflow technology and MEMS technology to fabricate atomic gas cells with multiple light transmission directions and controllable dimensions.
[0103] Compared to the method of directly etching through-hole structures on glass substrates, this disclosure utilizes glass reflow technology to easily fabricate glass chambers, avoiding the technical difficulties and high costs of etching glass through-holes. It has the advantages of simple operation and compatibility with MEMS technology.
[0104] By combining MEMS technology and alkali metal direct vapor deposition technology, the mass production of this glass chamber can be achieved, avoiding the generation of unwanted residues and reactants within the chamber. Utilizing the flexibility of MEMS technology, glass atomic gas chambers with different morphologies can be fabricated, not limited to cubes and cylinders, effectively preventing stray light from the laser beam within the gas chamber and improving the signal-to-noise ratio of the device.
[0105] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0106] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing an alkali metal atom gas cell, characterized in that, The preparation method includes: A mold is provided, the mold including a first surface and a second surface disposed opposite to each other, the mold having a plurality of closed grooves extending from the first surface to the second surface; Molten glass is filled into the closed groove using a hot reflow process, causing the molten glass to overflow outside the closed groove and cover the first surface. After the molten glass cools, a composite sheet is obtained, which includes nested molds and solid glass. The surface of the solid glass away from the mold is planarized. The mold in the composite sheet is removed by an etching process to obtain a glass substrate. The glass substrate has a plurality of atomic gas chamber shells. The shape of the atomic gas chamber shells corresponds to the closed grooves. A cavity is formed inside the cavity, and one end face of the atomic gas chamber shell is not closed. Alkali metal atoms are filled into the cavity of the atomic gas chamber shell; A silicon wafer is provided, and after aligning the silicon wafer with the unsealed end face of the atomic gas chamber shell, anodic bonding is performed to achieve sealing of the atomic gas chamber; Slicing is used to obtain multiple independent alkali metal atom gas chambers.
2. The method for preparing the alkali metal atom gas cell according to claim 1, characterized in that, The mold includes a silicon-based mold or a high-temperature metal mold; and / or, The closed groove includes an outer ring sidewall and at least one inner ring sidewall, wherein the cross-sectional shape of the inner ring sidewall perpendicular to the extension direction is circular, semi-circular, or polygonal.
3. The method for preparing the alkali metal atom gas cell according to claim 2, characterized in that, The closed groove includes an outer ring sidewall and two spaced-apart inner ring sidewalls located within the outer ring sidewall. The groove depth between the inner ring sidewalls is less than the depth of the rest of the closed groove. The cross-sectional shape of the inner ring sidewalls along the direction perpendicular to the extension is circular, semi-circular, or polygonal, so that the mold forms two spaced-apart columnar structures in the closed groove.
4. The method for preparing the alkali metal atom gas cell according to claim 1, characterized in that, Molten glass is filled into the closed groove using a hot reflow process, causing the molten glass to overflow outside the closed groove. After the molten glass cools, a composite sheet is obtained. The composite sheet includes nested molds and solid glass, comprising: A glass sheet is provided and placed on the first surface of the mold, and the mold and the glass sheet are clamped by a clamping tool; The mold and the glass sheet are placed in a heating furnace and heated for a preset time at a set temperature and pressure, so that the glass sheet forms molten glass and fills the closed groove; After the heating furnace is turned off and the molten glass and the mold are cooled to room temperature, the composite sheet is obtained.
5. The method for preparing the alkali metal atom gas cell according to claim 1, characterized in that, The preparation method further includes: after removing the mold in the composite sheet by an etching process to obtain a glass substrate, annealing the glass substrate to remove stress.
6. The method for preparing the alkali metal atom gas cell according to claim 5, characterized in that, The glass substrate is subjected to annealing treatment, including: The glass substrate is placed in an annealing furnace and annealed at 500-600°C for 30-45 minutes, and then cooled to room temperature.
7. The method for preparing the alkali metal atom gas cell according to claim 2, characterized in that, Provide molds, including: We provide silicon wafers, and use standard cleaning processes to clean and dry the substrate silicon wafers. Photoresist is spin-coated onto the silicon wafer, and a photoresist mask is prepared by photolithography. Based on the photoresist mask, a closed trench is prepared on the silicon wafer using a deep silicon etching process, and a columnar structure is obtained on the silicon wafer; Remove the residual photoresist from the silicon wafer and clean the silicon wafer using a standard cleaning process to obtain a silicon-based mold.
8. The method for preparing the alkali metal atom gas cell according to claim 2, characterized in that, The glass substrate is obtained by removing the mold from the composite sheet using an etching process, including: Prepare a KOH solution with a mass fraction of 25%~30%, and heat the KOH solution to 70℃; The composite sheet is immersed in KOH solution until the silicon-based mold separates from the glass substrate.
9. The method for preparing the alkali metal atom gas cell according to claim 1, characterized in that, Filling the cavity of the atomic gas chamber shell with alkali metal atoms includes: An alkali metal vapor reflector is prepared, wherein the alkali metal vapor reflector has several through holes; An alkali metal evaporation source, an alkali metal vapor reflector, and a glass substrate are placed sequentially from bottom to top inside an evaporation device, with the position of the through hole corresponding to the position of the cavity. Alkali metal is then filled into the cavity using a direct alkali metal vapor deposition method.
10. The method for preparing an alkali metal atom gas cell according to claim 1, characterized in that, The conditions for anodic bonding include: a bonding environment of nitrogen or inert gas with a pressure range of 100~1520 torr, a bonding temperature of 250~400℃, and a bonding voltage of 1000~1500V.
11. An alkali metal atom gas chamber, prepared according to the preparation method of any one of claims 1 to 10, characterized in that, The alkali metal atom chamber includes an atom chamber shell and a silicon wafer. One end face of the atom chamber shell is not closed and a cavity is formed therein. The silicon wafer is connected to the unclosed end face of the atom chamber shell by anodic bonding to form a sealed atom chamber, which is filled with alkali metal atoms.
12. The alkali metal atom gas chamber according to claim 11, characterized in that, The atomic gas chamber shell also includes a partition located inside the cavity, which divides the atomic gas chamber into two interconnected sub-chambers, which are filled with alkali metal atoms.