Method for manufacturing atomic cell and atomic cell

Abstract

The application discloses a kind of production methods of atomic gas chamber and atomic gas chamber, production method includes: providing glass substrate;Using laser to scan glass substrate surface, form closed modified track on glass substrate;Using wet etching process to etch glass substrate after laser scanning, form through hole in the thickness direction through glass substrate;Glass substrate side is bonded with first silicon wafer;Fill alkali metal atom and inert gas;The other side of glass substrate is bonded with second silicon wafer, form closed alkali metal gas chamber;With single alkali metal gas chamber as unit, obtain independent atomic gas chamber by dicing.The production method of atomic gas chamber and atomic gas chamber of the application, laser is used to scan glass substrate after modification, and through hole preparation is realized by combining wet etching, so that the batch preparation of small atomic gas chamber with two light transmission directions and controllable size is realized.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano manufacturing technology, specifically relating to a method for fabricating an atomic gas chamber and the atomic gas chamber itself. Background Technology

[0002] Atomic gas cells are core components for quantum state preparation and detection, and are widely used in sensors such as quantum frequency standards, magnetic field measurements, and angular velocity measurements. As quantum sensors develop towards portability and array-based designs, the miniaturization and mass production of atomic gas cells have become urgent needs.

[0003] Traditional glass blowing methods result in large-volume gas cells that are difficult to mass-produce. While existing MEMS atomic gas cells have achieved miniaturization, they only have one light-transmitting direction, limiting device design optimization. Patent CN105712282B achieves atomic gas cells with two light-transmitting directions by etching through-holes on a glass substrate and bonding silicon wafers, but its glass etching process is costly and inefficient, making it difficult to meet the needs of mass production.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for manufacturing an atomic gas chamber and an atomic gas chamber that can solve the problems in the prior art.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] A method for fabricating an atomic gas chamber includes:

[0008] A glass substrate is provided, the glass substrate including a first surface and a second surface disposed opposite each other in the thickness direction;

[0009] A laser is used to scan the first surface and / or the second surface to form a closed modification trajectory on the glass substrate;

[0010] The glass substrate after laser scanning is etched using a wet etching process, and the glass material is removed by using the modified trajectory as the etching path to form a through hole that penetrates the glass substrate in the thickness direction.

[0011] The first surface of the glass substrate is bonded to the first silicon wafer;

[0012] Alkali metal atoms and inert gas are introduced into the cavity formed by the through hole and the first silicon wafer;

[0013] The second surface of the glass substrate is bonded to the second silicon wafer to form a sealed alkali metal gas chamber;

[0014] By dividing the gas into individual alkali metal cells, independent atomic cells can be obtained.

[0015] In one or more embodiments of the present invention, in the laser scanning step, the scanning path of the laser on the glass substrate is a closed curve by controlling the movement of the sample stage carrying the glass substrate.

[0016] In one or more embodiments of the present invention, the shape of the figure formed by the closed curve includes a square, a rectangle, or a polygon; and / or,

[0017] The side length of the figure formed by the closed curve is 2mm-10mm.

[0018] In one or more embodiments of the present invention, in the laser scanning step, the laser is a pulsed laser with a wavelength of 1030 nm and a repetition frequency of 500 kHz to 2000 kHz.

[0019] In one or more embodiments of the present invention, the etching solution used in the wet etching process includes an HF solution, wherein the mass percentage concentration of the HF solution is 2.5%-40%.

[0020] In one or more embodiments of the present invention, the bonding is anodic bonding.

[0021] In one or more embodiments of the present invention, the alkali metal atom includes one or more of potassium, rubidium, and cesium; and / or,

[0022] The inert gas includes nitrogen or xenon; and / or,

[0023] The pressure of the inert gas is 100 Torr-1500 Torr.

[0024] In one or more embodiments of the present invention, the thickness of the glass substrate is 0.5 mm to 3 mm; and / or,

[0025] The diameter of the glass substrate is 2 inches to 6 inches.

[0026] In one or more embodiments of the present invention, the through hole is a millimeter-sized through hole.

[0027] An atomic gas chamber is manufactured using the above-described method for manufacturing atomic gas chambers.

[0028] Compared with the prior art, the atomic gas cell fabrication method and atomic gas cell of the present invention utilize laser scanning modification of glass substrate followed by wet etching to achieve through-hole fabrication, thereby realizing the mass production of small atomic gas cells with two light transmission directions and controllable size. This avoids the technical difficulties and high costs of traditional glass through-hole etching, and has the advantages of simple operation and compatibility with MEMS technology.

[0029] The atomic gas cell fabrication method and atomic gas cell of the present invention can flexibly control the planar shape and size of the through hole by adjusting the laser scanning path, and can prepare atomic gas cells with different morphological characteristics. The cavity structure can be optimized according to the actual optical path design, effectively avoiding the generation of reflection and stray light of laser beam on the inner wall of the gas cell, and improving the signal-to-noise ratio of the device.

[0030] The atomic gas chamber fabrication method and atomic gas chamber of the present invention adopt silicon-glass anodic bonding to achieve a fully sealed structure of the gas chamber, which has higher structural strength and better airtightness, can withstand higher operating temperatures and higher inert gas pressures, and helps to operate at higher atomic densities, further improving the sensitivity and stability of quantum sensors.

[0031] The atomic gas cell fabrication method and atomic gas cell of the present invention adopt a process flow of whole wafer-level processing followed by dicing and separation, which can simultaneously prepare hundreds of atomic gas cells on the same wafer, with good product consistency, high production efficiency, and is suitable for large-scale industrial production. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart of the method for fabricating the atomic gas chamber of the present invention;

[0034] Figures 2a-2g This is a flowchart illustrating the process steps of the method for fabricating the atomic gas chamber of the present invention.

[0035] Figure 3 This is a schematic diagram of the laser scanning path (modification trajectory) in the method for fabricating the atomic gas cell according to one embodiment of the present invention. Figure 2b Top view. Detailed Implementation

[0036] 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.

[0037] As mentioned in the background section, the atomic gas cell is currently the simplest device for preparing and detecting quantum states. It stores atomic vapor in a transparent container or a container with a transparent window, forming a closed system. The preparation and detection of quantum states are achieved through the interaction of laser light with the atomic vapor. As a core component of quantum sensors, the atomic gas cell plays a decisive role in device design and performance indicators, and has wide applications in sensors such as quantum frequency standards, electric and magnetic field measurements, and angle and angular velocity measurements. The portability and array requirements of quantum sensors are driving the miniaturization of atomic gas cells.

[0038] Traditional atomic gas cells are fabricated using glass blowing methods, resulting in large cell volumes and difficulties in mass production, which cannot meet application requirements. While MEMS-based atomic gas cells enable the mass production of miniaturized gas cells, they only have one light-transmitting direction, severely limiting device design and performance optimization.

[0039] To address the limitation on the direction of light transmission, researchers have made various attempts. In 2007, EJ Eklund et al. developed a method for fabricating spherical micro atomic gas cells combining glass blowing technology and MEMS technology, achieving mass production of spherical glass atomic gas cells with a diameter of 0.9 mm. However, the beam in the spherical structure needs to be refracted multiple times, which easily generates stray light, reduces the polarization obtained in the optical pumping process, and weakens the device response. Patent CN105712282B discloses a method based on etching a glass substrate to form a through-hole and bonding silicon wafers on both sides to prepare MEMS atomic gas cells that are transparent in two directions. However, its glass etching process is costly and inefficient. In 2022, V. Lucivero et al. fabricated a cavity on a glass substrate using laser direct writing technology and used UV-curable adhesive to form atomic gas cells that are transparent in three directions. However, the UV-curable adhesive limits the operating temperature and inert gas pressure of the gas cell, thus restricting the device performance. In the same year, Yu Mingzhi and others used laser drilling technology to create through-hole structures on glass substrates, and combined with multiple anodic bonding technology, they achieved the preparation of atomic gas chambers that allow light to pass through in three directions.

[0040] To address the problems of high cost and low efficiency in existing glass etching techniques, stray light generation from spherical structures, and limitations on operating temperature and pressure caused by UV-cured adhesives, this invention aims to propose a method for fabricating atomic gas chambers and the atomic gas chamber itself. This method utilizes laser scanning modification of a glass substrate followed by wet etching to fabricate through-holes, thereby enabling the mass production of small atomic gas chambers with two light transmission directions and controllable dimensions. This avoids the technical difficulties and high costs associated with traditional glass through-hole etching, and offers advantages such as simple operation and compatibility with MEMS technology. This invention allows for flexible control of the planar shape and size of the through-holes by adjusting the laser scanning path, enabling the fabrication of atomic gas chambers with different morphological characteristics. The cavity structure can be optimized according to the actual optical path design, effectively avoiding laser beam reflection and stray light generation on the inner wall of the gas chamber, thus improving the device's signal-to-noise ratio.

[0041] like Figure 1 As shown, the method for fabricating the atomic gas chamber of the present invention specifically includes the following steps:

[0042] S1, providing a glass substrate, the glass substrate including a first surface and a second surface disposed opposite to each other in the thickness direction;

[0043] S2, using a laser to scan the first surface and / or the second surface to form a closed modification trajectory on the glass substrate;

[0044] S3 uses a wet etching process to etch the glass substrate after laser scanning, removing the glass material with the modification trajectory as the etching path, forming a through hole that penetrates the glass substrate in the thickness direction;

[0045] S4, bonding the first surface of the glass substrate to the first silicon wafer;

[0046] S5, alkali metal atoms and inert gas are filled into the cavity formed by the through hole and the first silicon wafer;

[0047] S6, the second surface of the glass substrate is bonded to the second silicon wafer to form a closed alkali metal gas chamber;

[0048] S7 is obtained by dividing the gas into individual alkali metal cells to obtain independent atomic cells.

[0049] Before step S2, the process includes polishing, cleaning, and drying the first and second surfaces of the glass substrate for later use. The thickness of the glass substrate is 0.5mm-3mm. The diameter of the glass substrate is 2 inches-6 inches. The glass substrate is preferably a BF33 glass substrate, which is BOROFLOAT® 33 borosilicate float glass manufactured by Schott AG, Germany. The coefficient of thermal expansion of BF33 glass is close to that of monocrystalline silicon, effectively reducing thermal stress and preventing device cracking during bonding. Simultaneously, it has excellent light transmittance, exhibiting high transmittance in the visible and near-ultraviolet bands, and good high-temperature resistance, with a long-term operating temperature up to 450℃, meeting the high-temperature requirements of atomic gas chambers.

[0050] In step S2, the glass substrate is fixed on a triaxial displacement sample stage. By controlling the movement of the triaxial displacement sample stage supporting the glass substrate, the scanning path of the laser on the glass substrate is made into a closed curve. The shape of the pattern formed by the closed curve can be a square, rectangle, or polygon. The side length of the pattern formed by the closed curve is 2mm-10mm. The laser is a pulsed laser with a wavelength of 1030nm and a repetition frequency of 500kHz-2000kHz.

[0051] In step S3, the etching solution used in the wet etching process includes, but is not limited to, HF solution, with a mass percentage concentration of 2.5%-40%. The vias formed on the glass substrate are millimeter-scale vias.

[0052] In steps S4 and S6, the bonding process is preferably anodizing.

[0053] In step S5, the alkali metal atoms include, but are not limited to, one or more of potassium, rubidium, and cesium. The inert gas includes, but is not limited to, nitrogen or xenon. The pressure of the inert gas is 100 Torr-1500 Torr.

[0054] In the above technical solution, an ultrashort pulse laser is used to selectively modify the BF33 borosilicate glass substrate. The modified region exhibits a change in the glass material structure, resulting in a significantly higher etching rate in subsequent wet etching compared to the unmodified region. This enables efficient and low-cost processing of glass through-holes. Subsequently, a three-layer silicon-glass-silicon structure is sealed through two anodic bonding processes, with alkali metal filling and inert gas encapsulation completed during the process. Finally, individual atomic gas chambers are obtained through dicing.

[0055] Figures 2a to 2g The following is a flowchart illustrating the process steps of the method for fabricating the atomic gas chamber of the present invention. The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0056] like Figure 2aAs shown, a glass substrate 10 of a certain thickness is selected, and polished, cleaned, and dried using standard processes. The glass substrate 10 includes a first surface and a second surface that are arranged opposite each other in the thickness direction.

[0057] like Figure 2b As shown, a pulsed laser is used to scan the first and / or second surfaces of the glass substrate 10 to modify the glass substrate 10, forming closed modification tracks 22 on the glass substrate 10. The region 21 enclosed by the modification tracks 22 can be a square with a side length of 2 mm and an array period of 4 mm, as shown. Figure 3 As shown, the region 21 enclosed by the closed modified trajectory 22 is the region where the through hole 23 needs to be formed later.

[0058] It is understood that the region 21 enclosed by the modified trajectory 22 can also be a rectangle or a polygon, and this application does not limit this.

[0059] like Figure 2c As shown, the modified glass substrate 10 is thoroughly etched using an etching solution. The etching rate of the modified trajectory 22 region in the etching solution is much higher than that of the unmodified region. After etching, the glass material in the region 21 enclosed by the modified trajectory 22 is removed to obtain a glass substrate 10 with through holes 23.

[0060] like Figure 2d As shown, the first silicon wafer 30 is placed Figure 2c On the glass substrate 10 obtained in the previous step, the first anodic bonding is performed. The bonding temperature is controlled between 250℃ and 400℃, the bonding voltage is controlled between 1000V and 1500V, and the vacuum degree is 10. -4 Pa. A suitable bonding current is set, and bonding is completed when the loop current drops to less than one-tenth of the peak current, resulting in a glass-silicon bonded structure;

[0061] like Figure 2e As shown, the alkali metal direct vapor deposition method is used to deposit... Figure 2d The through-hole region A of the bonded structure obtained in the step is filled with alkali metal.

[0062] like Figure 2f As shown, Figure 2e The alkali metal-filled bonding structure obtained in the previous step is placed on the second silicon wafer 40 for a second anodic bonding. Bonding is performed in an inert gas atmosphere of 200-1500 Torr, with the bonding temperature controlled between 250°C and 400°C and the bonding voltage controlled between 1000V and 1500V. A suitable bonding current is set, and bonding is completed when the loop current drops to less than one-tenth of the peak current, resulting in a wafer-level atomic gas cell array.

[0063] like Figure 2g As shown, the wafer-level atomic gas cell array is cut and separated by a dicing process to obtain individual atomic gas cells.

[0064] The present invention also provides an atomic gas chamber manufactured using the above-described method for manufacturing atomic gas chambers.

[0065] The atomic gas chamber of this invention adopts a sandwich structure, comprising three layers: a BF33 glass substrate and two silicon wafers. The BF33 glass substrate is the middle layer and has through-holes. The top and bottom layers are silicon wafers. The silicon wafers are anodicly bonded to the glass substrate to form a sealed alkali metal gas chamber. The through-holes in the center of the BF33 glass substrate are millimeter-sized through-holes fabricated using laser-induced etching technology.

[0066] Compared with the prior art, the atomic gas cell fabrication method and atomic gas cell of the present invention utilize laser scanning modification of glass substrate followed by wet etching to achieve through-hole fabrication, thereby realizing the mass production of small atomic gas cells with two light transmission directions and controllable size. This avoids the technical difficulties and high costs of traditional glass through-hole etching, and has the advantages of simple operation and compatibility with MEMS technology.

[0067] The atomic gas cell fabrication method and atomic gas cell of the present invention can flexibly control the planar shape and size of the through hole by adjusting the laser scanning path, and can prepare atomic gas cells with different morphological characteristics. The cavity structure can be optimized according to the actual optical path design, effectively avoiding the generation of reflection and stray light of laser beam on the inner wall of the gas cell, and improving the signal-to-noise ratio of the device.

[0068] The atomic gas chamber fabrication method and atomic gas chamber of the present invention adopt silicon-glass anodic bonding to achieve a fully sealed structure of the gas chamber, which has higher structural strength and better airtightness, can withstand higher operating temperatures and higher inert gas pressures, and helps to operate at higher atomic densities, further improving the sensitivity and stability of quantum sensors.

[0069] The atomic gas cell fabrication method and atomic gas cell of the present invention adopt a process flow of whole wafer-level processing followed by dicing and separation, which can simultaneously prepare hundreds of atomic gas cells on the same wafer, with good product consistency, high production efficiency, and is suitable for large-scale industrial production.

[0070] Example 1:

[0071] Step 1: Select a 4-inch BF33 glass substrate with a thickness of 2mm, clean it using the standard cleaning process, and then dry it.

[0072] Step 2: Modify the glass substrate using a pulsed laser with a center wavelength of 1030 nm, a pulse width of 200 fs, and a repetition frequency of 500 kHz. Control the sample stage to move so that the laser scanning path on the BF33 glass substrate is a square closed curve with a side length of 2 mm and an array period of 4 mm.

[0073] Step 3: Use a 5% HF solution to thoroughly etch the modified glass substrate to remove the glass material in the laser-modified area, resulting in a glass substrate with through holes.

[0074] Step 4: Select a silicon wafer with a thickness of 500μm and place it on the glass substrate with through holes obtained in Step 3 for anodic bonding. The bonding temperature is controlled between 250℃ and 400℃, the bonding voltage between 1000V and 1500V, and the vacuum level is controlled at 10... -4 Pa. Set an appropriate bonding current, and when the loop current drops to less than one-tenth of the peak current, the bonding is considered complete, resulting in a glass-silicon bonded structure.

[0075] Step 5: Use the alkali metal direct vapor deposition method to fill the through-hole region of the bonding structure obtained in Step 4 with alkali metal.

[0076] Step Six: Place the alkali metal-filled bonding structure obtained in Step Five onto another 500 μm thick silicon wafer for a second anodic bonding. Bonding is performed in a 200 Torr nitrogen atmosphere, with the bonding temperature controlled between 250°C and 400°C, and the bonding voltage controlled between 1000V and 1500V. A suitable bonding current is set; bonding is considered complete when the loop current drops to less than one-tenth of the peak current, resulting in a wafer-level composite. 87 Rb atom gas chamber array.

[0077] Step 7: Process the wafer-level wafers obtained in Step 6. 87 The Rb atom gas cell array is cut and separated by a dicing process to obtain individual atom gas cells.

[0078] Example 2:

[0079] The difference between this embodiment and Embodiment 1 is that the thickness of the BF33 glass substrate in step one can be selected from 0.5mm to 3mm, and the diameter can be from 2 inches to 6 inches. Other steps and parameters are the same as in Embodiment 1.

[0080] Example 3:

[0081] The difference between this embodiment and Embodiment 1 or 2 is that the repetition frequency of the pulsed laser in step two can be selected within the range of 500kHz to 2000kHz. Other steps and parameters are the same as in Embodiment 1 or 2.

[0082] Example 4:

[0083] The difference between this embodiment and embodiments 1-3 is that the closed curve formed by the scanning path of the laser on the BF33 glass substrate in step two is not limited to a square, but can also be a rectangle or a regular polygon, with a side length or equivalent size in the range of 2mm to 10mm. Other steps and parameters are the same as in embodiments 1-3.

[0084] Example 5:

[0085] The difference between this embodiment and embodiments 1-4 is that, in step three, depending on the thickness of the glass substrate, an HF solution with a mass fraction of 2.5% to 40% can be used to etch the glass substrate. Other steps and parameters are the same as in embodiments 1-4.

[0086] Example 6:

[0087] The difference between this embodiment and embodiments 1-5 is that the alkali metals in steps five and six are not limited to... 87 Rb can also be replaced by other alkali metal elements such as K (potassium) or Cs (cesium). Other steps and parameters are the same as in Examples 1-5.

[0088] Example 7:

[0089] The difference between this embodiment and Embodiments 1-6 is that the nitrogen filling pressure in step six can be selected from the range of 100 Torr to 1500 Torr. Other steps and parameters are the same as in Embodiments 1-6.

[0090] 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.

[0091] 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 fabricating an atomic gas chamber, characterized in that, include: A glass substrate is provided, the glass substrate including a first surface and a second surface disposed opposite each other in the thickness direction; A laser is used to scan the first surface and / or the second surface to form a closed modification trajectory on the glass substrate; The glass substrate after laser scanning is etched using a wet etching process, and the glass material is removed by using the modified trajectory as the etching path to form a through hole that penetrates the glass substrate in the thickness direction. The first surface of the glass substrate is bonded to the first silicon wafer; Alkali metal atoms and inert gas are introduced into the cavity formed by the through hole and the first silicon wafer; The second surface of the glass substrate is bonded to the second silicon wafer to form a sealed alkali metal gas chamber; By dividing the gas into individual alkali metal cells, independent atomic cells can be obtained.

2. The method for fabricating an atomic gas chamber according to claim 1, characterized in that, In the laser scanning step, the sample stage carrying the glass substrate is moved to make the scanning path of the laser on the glass substrate a closed curve.

3. The method for fabricating the atomic gas chamber according to claim 2, characterized in that, The shape of the figure formed by the closed curve includes a square, a rectangle, or a polygon; and / or, The side length of the figure formed by the closed curve is 2mm-10mm.

4. The method for fabricating an atomic gas chamber according to claim 1, characterized in that, In the laser scanning step, the laser is a pulsed laser with a wavelength of 1030nm and a repetition frequency of 500kHz-2000kHz.

5. The method for fabricating an atomic gas chamber according to claim 1, characterized in that, The wet etching process uses an etching solution including an HF solution, wherein the HF solution has a mass percentage concentration of 2.5%-40%.

6. The method for fabricating an atomic gas chamber according to claim 1, characterized in that, The bonding is anodic bonding.

7. The method for fabricating an atomic gas chamber according to claim 1, characterized in that, The alkali metal atoms include one or more of potassium, rubidium, and cesium; and / or, The inert gas includes nitrogen or xenon; and / or, The pressure of the inert gas is 100 Torr-1500 Torr.

8. The method for fabricating an atomic gas chamber according to claim 1, characterized in that, The thickness of the glass substrate is 0.5mm-3mm; and / or, The diameter of the glass substrate is 2 inches to 6 inches.

9. The method for fabricating an atomic gas chamber according to claim 1, characterized in that, The through hole is a millimeter-sized through hole.

10. An atomic gas chamber, characterized in that, It is manufactured using the method for manufacturing an atomic gas chamber as described in any one of claims 1-9.

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