A miniaturized magnetometer chamber and its preparation method

Abstract

This application discloses a miniaturized magnetometer gas chamber and its fabrication method. The gas chamber includes several sides, which are fabricated by anodic bonding and sealing. A first side and a second side are arranged opposite to each other. Metastable excitation coils are disposed on the first surfaces of both the first and second sides. Metal mirrors are disposed on the second surfaces of both the first and second sides. The second surfaces of both the first and second sides are located inside the gas chamber, which is filled with... 3 He; the dimensions of the air chamber are in millimeters. The embodiments of this application can improve the detection sensitivity and reliability of the magnetometer. This application can be widely applied in the field of magnetic field sensors.

Description

Technical Field

[0001] This application relates to the field of magnetic field sensor technology, and in particular to a miniaturized magnetometer chamber and its preparation method. Background Technology

[0002] Current quantum magnetometers are generally optically pumped atomic magnetometers, which achieve polarization of alkali metal atoms through optical pumping, and then detect the magnetic field by detecting the response of the polarized alkali metal atoms to the magnetic field using probe light. However, alkali metal atoms have low saturated vapor pressure at room temperature, making it difficult to achieve high-sensitivity magnetic field detection. In addition, prolonged high temperatures pose a serious challenge to the gas chamber and the reliability during operation. Summary of the Invention

[0003] The main objective of this application is to propose a miniaturized magnetometer chamber and its preparation method, which aims to improve the detection sensitivity and reliability of the magnetometer.

[0004] To achieve the above objectives, one aspect of this application proposes a miniaturized magnetometer chamber. The chamber includes several sides, which are fabricated by anodic bonding. A first side and a second side are arranged opposite each other. A metastable excitation coil is disposed on the first surface of both the first and second sides. A metal reflector is disposed on the second surface of both the first and second sides. The second surfaces of both the first and second sides are located inside the chamber, which is filled with... 3 He; the dimensions of the air chamber are in millimeters.

[0005] In some embodiments, the materials of the first side and the second side include borosilicate glass wafers.

[0006] In some embodiments, the material of the other sides of the gas chamber besides the first and second sides includes silicon wafers.

[0007] In some embodiments, the material of the metal reflector includes several metal materials with a reflectivity greater than a preset value.

[0008] In some embodiments, a dense film is provided on the surface of the interior of the gas chamber.

[0009] In some embodiments, a protective film is provided on the surface of the metastable excitation coil.

[0010] To achieve the above objectives, another aspect of this application provides a method for preparing a miniaturized magnetometer chamber, comprising: Prepare the first and second side surfaces; Prepare the other sides of the gas chamber besides the first and second sides; The first side, the second side, and the other sides are assembled and filled by anodic bonding. 3 He, forms an air chamber.

[0011] In some embodiments, the first side is prepared by the following method: A first substrate on the first side is obtained and cleaned. Photoresist is coated, patterned, and metastable excitation coils are fabricated on the first surface of the cleaned first substrate. A protective film is prepared on the surface of the metastable excitation coil and then cleaned. Photoresist was coated, patterned, and a metal mirror was fabricated on the second surface of the first substrate after cleaning, followed by cleaning and drying.

[0012] In some embodiments, the sides other than the first and second sides are prepared by the following method: Obtain the second substrate from the other side and clean the second substrate. Coat one side surface of the cleaned second substrate with photoresist, pattern it, and prepare vias. Clean and dry it.

[0013] In some embodiments, the first side, the second side, and other sides are assembled and filled by anodic bonding. 3 He, forming air chambers, includes: The first side, after being cleaned and dried, is bonded to the other sides by anodizing to form a preform. The prefabricated component is assembled with the cleaned and dried second side surface and then filled. 3 He forms a gas chamber through anodic bonding.

[0014] The embodiments of this application include at least the following beneficial effects: This application provides a miniaturized magnetometer gas chamber and its preparation method. The miniaturized magnetometer gas chamber includes several sides, which are prepared by anodic bonding and sealing. A first side and a second side are arranged opposite each other. Metastable excitation coils are provided on the first surfaces of both the first and second sides, and metal mirrors are provided on the second surfaces of both sides. The gas chamber is filled with He (³He), and the size of the gas chamber is in millimeters. The metastable excitation coils and metal mirrors are used to ionize He atoms and perform multiple reflections of light to increase the interaction time between polarized atoms and the laser, thereby improving the detection sensitivity of the magnetometer. Furthermore, this magnetometer uses He as the working atom, which is a gas at room temperature, eliminating the need for additional heating of the gas chamber. This significantly reduces the temperature resistance requirements of the device, thereby improving the reliability of the magnetometer. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the miniaturized magnetometer chamber provided in the embodiments of this application; Figure 2 This is a flowchart of the method for preparing the miniaturized magnetometer chamber provided in the embodiments of this application; Figure 3 This is a flowchart of the fabrication process of the miniaturized magnetometer gas chamber provided in the embodiments of this application.

[0016] The meanings of the markings in the attached diagram are as follows: 1. Metastable excitation coil; 2. Metal mirror; 3. First or second side; 4. Other sides; 5. Photoresist; 6. Silicon dioxide; 7. Electrode plate; 8. Sealing cavity of anode bonding machine; 9. Pressing plate; 10. Insert plate. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0018] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”

[0019] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0021] 3He atoms can be excited to a metastable state by discharge or electron collisions. This metastable state has a long lifetime, and its atomic spin is extremely sensitive to magnetic fields, making it suitable for direct magnetic sensing. Furthermore, this magnetometer employs... 3 He, as the working atom, is a gas at room temperature, eliminating the need for additional heating of the gas chamber, which greatly reduces the device's temperature resistance requirements.

[0022] Currently, magnetometers are developing towards miniaturization and micro-miniaturization. Traditional glass-blown gas cells no longer meet the requirements for miniaturization. The development of MEMS technology has made it possible to miniaturize gas cells. However, miniaturization of the gas cell inevitably means a reduction in the interaction time between light and working atoms, resulting in a lower signal-to-noise ratio, which directly affects the sensitivity of the magnetometer. Furthermore, unlike ordinary gas cells, this gas cell requires a high-frequency electric field to achieve metastable excitation of He atoms, thereby realizing atomic pump polarization. This necessitates the fabrication of metastable excitation coils capable of generating high-frequency electric fields. 3 Metastable excitation of He atoms enables high-precision detection of magnetic fields.

[0023] This application provides a miniaturized magnetometer gas chamber. The gas chamber includes several sides, which are fabricated by anodic bonding and sealing. A first side and a second side are arranged opposite each other. A metastable excitation coil is disposed on the first surface of both the first and second sides. A metal reflector is disposed on the second surface of both the first and second sides. The second surfaces of both the first and second sides are located inside the gas chamber, which is filled with... 3 He; the dimensions of the air chamber are measured in millimeters.

[0024] In some embodiments, the material of the first side and the second side includes borosilicate glass wafers.

[0025] In some embodiments, the material of the other sides of the gas chamber besides the first and second sides includes silicon wafers.

[0026] It should be noted that the other sides of the air chamber besides the first and second sides are determined according to the actual application, and this embodiment does not impose specific limitations. For example, if the air chamber is a cuboid or a cube, in addition to the first and second sides, the air chamber also includes the other four sides around the perimeter.

[0027] like Figure 1 As shown, in a specific embodiment, the gas chamber is mainly fabricated by anodizing other sides (4) (a layer of double-sided polished silicon wafer), the first side, and the second side (3) (two layers of double-sided polished glass wafer). The gas chamber is filled with... 3He is the working gas. Metastable excitation coils (1) and metal mirrors (2) are fabricated on both sides of the glass wafer. During operation, the metastable excitation coils (1) generate a high-frequency electric field. 3 He atoms are excited into a metastable state. Pump light enters the gas cell and passes through the gap between the metal mirror (2) and the side of the gas cell, undergoing multiple reflections to achieve metastable state. 3 The polarization of He atoms, followed by their ejection from the other side of the gas chamber, achieves excitation. 3 Pumping and detection of He atoms. Among them, the metastable excitation coil (1) is prepared on the outer surface of the glass wafer facing the gas chamber. It is a ring-shaped planar coil structure. Its projection range in the plane preferably covers the gas chamber cavity area to ensure the uniformity of metastable excitation distribution in the gas chamber. The metal mirror (2) is prepared on the inner surface of the glass wafer facing the gas chamber. It is a rectangular planar reflective structure and its size needs to be slightly smaller than the cavity size.

[0028] In one specific embodiment, the relevant structural dimensions of the miniaturized magnetometer chamber are as follows: the overall dimensions of the chamber are: length × width × height = 6mm × 6mm × 4mm; the cavity dimensions are: length × width × height = 4mm × 4mm × 3mm; and the dimensions of the metal reflector are: length × width = 3.6mm × 3.6mm.

[0029] In some embodiments, the material of the metal reflector includes several metal materials with a reflectivity greater than a preset value.

[0030] It should be noted that the specific material of the metal reflector is determined based on the actual application, and this embodiment does not impose specific limitations. For example, the material of the metal reflector includes, but is not limited to, metals with good reflectivity such as chromium, gold, and silver.

[0031] In some embodiments, a dense film is provided on the surface of the gas chamber.

[0032] The presence of a dense film on the surface of the gas chamber can reduce permeation and leakage, thereby improving the stability and reliability of the gas chamber. It should be noted that the specific material of the dense film is determined based on the actual application; this embodiment does not impose specific limitations, such as an Al2O3 film.

[0033] In some embodiments, a protective film is provided on the surface of the metastable excitation coil.

[0034] A protective thin film on the surface of the metastable excitation coil can reduce external interference to the metastable excitation coil and improve the reliability of detection. It should be noted that the specific material of the protective thin film is determined according to the actual application; this embodiment does not impose specific limitations, such as SiO2 thin film.

[0035] See Figure 2This application also provides a method for preparing a miniaturized magnetometer chamber, which includes steps S101 to S103.

[0036] Step S101: Prepare the first side surface and the second side surface; Step S102: Prepare the other sides of the air chamber besides the first and second sides; Step S103: Assemble and fill the first side, the second side, and the other sides by anodic bonding. 3 He, forms an air chamber.

[0037] The first and second sides can be the same, and their fabrication methods can be identical. Metastable excitation coils and metal mirrors are fabricated on the two surfaces of the first and second sides, respectively. Other sides in the gas chamber besides the first and second sides can also be the same, and their fabrication methods can be identical.

[0038] In some embodiments, the first side is prepared by the following method: Step S201: Obtain the first substrate on the first side and clean the first substrate. Coat the first surface of the cleaned first substrate with photoresist, pattern it, and prepare a metastable excitation coil. Step S202: Prepare a protective film on the surface of the metastable excitation coil and clean it; Step S203: Coat the second surface of the cleaned first substrate with photoresist, pattern it, and fabricate a metal mirror, then clean and dry it.

[0039] It should be noted that the cleaning standard for the first substrate is determined based on the actual application, and this embodiment does not impose specific limitations. The patterning treatment of the first surface of the first substrate is determined according to the shape of the metastable excitation coil. The metastable excitation coil can be a metal coil, which can be prepared by methods such as magnetron sputtering or chemical vapor deposition. Similarly, the patterning treatment of the second surface of the first substrate is determined according to the shape of the metal mirror. The metal mirror can be a metal thin film, which can be prepared by methods such as magnetron sputtering or chemical vapor deposition.

[0040] In some embodiments, the sides other than the first and second sides are prepared by the following method: Step S301: Obtain the second substrate from the other sides and clean the second substrate. Coat one side of the cleaned second substrate with photoresist, pattern it, and prepare vias. Clean and dry it.

[0041] It should be noted that the cleaning standard for the second substrate is determined based on the actual application, and this embodiment does not impose specific limitations. The patterning treatment of one side surface of the second substrate and the preparation of through holes are determined based on the actual application, and this embodiment does not impose specific limitations.

[0042] In some embodiments, the first side, the second side, and other sides are assembled and filled by anodic bonding. 3 He, forming air chambers, includes: Step S401: The first side, after being cleaned and dried, is bonded to the other sides by anodizing to form a preform; Step S501: Assemble the preform with the cleaned and dried second side and fill it. 3 He forms a gas chamber through anodic bonding.

[0043] The first side, after being cleaned and dried, is bonded to the other sides using anodizing to form a preform. Only one side of the preform may remain. Then, the preform and the cleaned and dried second side are placed in a sealed cavity for assembly. The sealed cavity is first evacuated and then filled with... 3 He forms a gas chamber through anodic bonding under specific temperature and pressure conditions.

[0044] In one specific embodiment, see Figure 3 The fabrication process of the miniaturized magnetometer chamber is as follows: (a) The other side (4) (silicon wafer) is cleaned using the RCA standard cleaning process. After cleaning, Az4620 photoresist (5) is coated on the surface of the other side (4) (silicon wafer) using a spin coating process. (b) Photolithography is performed on the other side (4) (silicon wafer) to pattern the other side (4); (c) Using photoresist (5) as a mask, dry etching is performed on other sides (4) using ICP dry etching process to complete the preparation of through-silicon vias; (d) Use acetone, anhydrous ethanol and deionized water to clean the other sides (4) to remove photoresist. Then, process the silicon wafer with RCA standard cleaning process to remove organic matter, metal and dust particles on the other sides (4) and dry it in a vacuum drying oven for later use. (e) The first and second sides (3) (BF33 glass wafer) are cleaned and Az4620 photoresist (5) is applied to one side of them; (f) Patterning is performed on one side of the glass wafer using photolithography; (g) Using magnetron sputtering, 30 nm chromium and 300 nm gold were sputtered onto the glass surface, and then the excess metal was removed by stripping process to complete the preparation of metastable excitation coil (1). (h) Using PECVD process, a 500nm SiO2 layer (6) is prepared on the sputtered metal surface to protect the metastable excitation coil; (i) The pad area of ​​the metastable excitation coil (1) is patterned by photolithography, and then the SiO2 (6) of the pad area is removed by ICP dry etching process, and then the glass wafer is cleaned. (j) Coat the other side of the glass wafer with photoresist (5); (k) The glass wafer is patterned using photolithography. (l) 20 nm chromium and 200 nm gold were sputtered sequentially on the surface of a glass wafer using magnetron sputtering. (m) The metal in the photoresist area is removed by a stripping process to realize the preparation of the metal mirror (2). Then the glass wafer is cleaned and dried by acetone, anhydrous ethanol and deionized water and then set aside. (n) Place the glass wafer and the silicon wafer in the anodic bonding machine and press them together using the electrode plate (7) to achieve the first anodic bonding (pre-formed part) between silicon and glass under the conditions of 300°C and 1000V voltage. (o) Place the preform in the sealing cavity (8) of the anodic bonding machine, place the insert (10) between the preform and the glass wafer (3) and clamp it with the pressure plate (9), then evacuate the sealing cavity (8) and fill it with about 200 Pa. 3 He gas; (p) Remove the insert (10) and the press (9), move the bonding machine plate (7) to clamp the preform with the glass wafer (3), and seal the gas chamber at 300°C and 1000V. (q) Remove the bonded wafer and dic it to obtain a single gas cell.

[0045] The embodiments of this application include at least the following beneficial effects: This application provides a miniaturized magnetometer gas chamber and its preparation method. The miniaturized magnetometer gas chamber includes several sides, which are prepared by anodic bonding and sealing. The first side and the second side are arranged opposite to each other. Metastable excitation coils are provided on the first surfaces of both the first and second sides, and metal mirrors are provided on the second surfaces of both the first and second sides. The gas chamber is filled with ³He, and the size of the gas chamber is in millimeters. Through the metastable excitation coils and the metal mirrors, the ionization of ³He atoms and multiple reflections of light are used to increase the interaction time between polarized atoms and laser light, thereby improving the detection sensitivity of the magnetometer. In addition, the magnetometer uses ³He as the working atom, which is a gas at room temperature and does not require additional heating of the gas chamber. This greatly reduces the temperature resistance requirements of the device, thereby improving the reliability of the magnetometer.

[0046] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0047] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.

[0048] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0049] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A miniaturized magnetometer chamber, characterized in that, The gas chamber includes several sides, which are fabricated by anodic bonding and sealing. A first side and a second side are arranged opposite each other. A metastable excitation coil is disposed on the first surface of both the first and second sides. A metal reflector is disposed on the second surface of both the first and second sides. The second surfaces of both the first and second sides are located inside the gas chamber, which is filled with... 3 He; the dimensions of the air chamber are in millimeters.

2. The air chamber according to claim 1, characterized in that, The materials of the first side and the second side include borosilicate glass wafers.

3. The air chamber according to claim 1, characterized in that, The material of the other sides of the gas chamber, excluding the first and second sides, includes silicon wafers.

4. The air chamber according to claim 1, characterized in that, The metal reflector is made of several types of metal materials with reflectivity greater than a preset value.

5. The air chamber according to claim 1, characterized in that, A dense film is provided on the surface of the gas chamber.

6. The air chamber according to claim 1, characterized in that, The surface of the metastable excitation coil is provided with a protective film.

7. A method for preparing a miniaturized magnetometer chamber, characterized in that, For preparing the gas chamber according to any one of claims 1-6, comprising: Prepare the first and second side surfaces; Prepare the other sides of the gas chamber besides the first and second sides; The first side, the second side, and the other sides are assembled and filled by anodic bonding. 3 He, forms an air chamber.

8. The preparation method according to claim 7, characterized in that, The first side surface is prepared by the following method: A first substrate on the first side is obtained and cleaned. Photoresist is coated, patterned, and metastable excitation coils are fabricated on the first surface of the cleaned first substrate. A protective film is prepared on the surface of the metastable excitation coil and then cleaned. Photoresist was coated, patterned, and a metal mirror was fabricated on the second surface of the first substrate after cleaning, followed by cleaning and drying.

9. The preparation method according to claim 7, characterized in that, Other than the first and second sides, the other sides are prepared by the following method: Obtain the second substrate from the other side and clean the second substrate. Coat one side surface of the cleaned second substrate with photoresist, pattern it, and prepare vias. Clean and dry it.

10. The preparation method according to claim 7, characterized in that, The first side, the second side, and the other sides are assembled and filled by anodic bonding. 3 He, forming air chambers, includes: The first side, after being cleaned and dried, is bonded to the other sides by anodizing to form a preform. The prefabricated component is assembled with the cleaned and dried second side surface and then filled. 3 He forms a gas chamber through anodic bonding.

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