Metal gas filled cell and its manufacturing method

Abstract

A manufacturing method according to the present invention comprises: attaching a first glass plate (11) to a first surface (10p) of a cell body (10) to form a lid on a gas generation part (20) and a droplet port (16); injecting a raw material solution (34a) of a metal gas through the droplet port (16) in a state where the first glass plate (11) is located below the gas generation part (20) in the vertical direction to introduce the raw material solution (34a) into the gas generation part (20); and vaporizing a solvent contained in the raw material solution (34a) to cause deposition of a solid raw material (34b) of the metal gas in the gas generation part (20).

Description

[Technical Field]

[0001] The present invention relates to a metal gas-filled cell and a method for manufacturing the same. [Background technology]

[0002] Research and development into the miniaturization of various atomic sensor devices is underway worldwide, including atomic clocks that can achieve highly accurate time synchronization and atomic magnetometers that measure biomagnetism with high sensitivity. For example, if atomic clocks can be miniaturized using MEMS (Micro Electro Mechanical Systems) processing technology, it will be possible to replace current quartz oscillators with atomic clocks. It is also expected that atomic clocks will be used in a variety of devices, such as smartphones and ultra-small satellites.

[0003] The atomic clock has a gas-filled cell as its main component, which contains an alkali metal gas and a buffer gas sealed in a container. 133 When using Cs, the quantum mechanical interference effect of Cs By using CPT (Coherent Population Trapping) resonance, which is the result of this technique, it is possible to realize atomic clocks that are compact, energy-efficient, and highly accurate. Frequency stability is one of the important indicators of atomic clock performance. Frequency stability is evaluated in terms of short-term stability and long-term stability. Short-term stability is theoretically determined by the product of the Q value of the CPT resonance and the S / N ratio. Long-term stability is evaluated by phenomena such as frequency fluctuations caused by changes over time in both the light intensity of the excitation semiconductor laser, which is the measurement condition for CPT resonance, and the partial pressure of the buffer gas inside the gas-filled cell. Therefore, technology for fabricating gas-filled cells is important to improve the performance of atomic clocks.

[0004] Patent Document 1 describes an example of a conventional gas-filled cell. The alkali metal cell described in Patent Document 1 includes a silicon member having a cell interior, a pair of glass plates attached to both sides of the silicon member, and an alkali metal source disposed inside the cell. The alkali metal source is solid CsN3. Cs vapor and N2 are generated by irradiating the CsN3 with UV light or laser light.

[0005] Patent Document 1 (FIGS. 11 and 12) also discloses a so-called two-chamber gas-filled cell. The two-chamber gas-filled cell has an optical chamber for irradiating alkali metal gas with laser light and a chamber for charging the alkali metal raw material. The two-chamber system has the advantages of being able to easily generate alkali metal gas and not leaving raw material in the optical chamber, and is therefore becoming the mainstream of gas-filled cells. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-38382 Summary of the Invention [Problem to be solved by the invention]

[0007] The Cs vapor generation method using the decomposition reaction of CsN3 is said to be able to generate high-purity Cs vapor. However, it is not easy to efficiently generate Cs vapor from solid CsN3. For example, if CsN3 is heated in a high vacuum and the temperature of CsN3 reaches the melting point of 310°C or higher, CsN3 undergoes a decomposition reaction accompanied by scattering. Even if solid CsN3 is heated at temperatures below ℃, the amount of Cs required to obtain CPT resonance is Therefore, it is usually necessary to generate Cs vapor slowly (e.g., over 24 hours) by UV irradiation.

[0008] An object of the present invention is to provide a technique for generating metal gas more efficiently and in a shorter time while employing a vapor generation method using a chemical reaction. [Means for solving the problem]

[0009] The present invention provides a cell body including a first surface, a second surface, a drip port which is a through-hole extending from the first surface to the second surface, and a gas generator having a plurality of grooves opening in the first surface; a first glass plate attached to the first surface of the cell body; and a cap for the gas generator and the drip port; injecting a metal gas raw material solution into the drip port while the first glass plate is positioned vertically below the gas generator, and introducing the raw material solution into the gas generator; evaporating a solvent contained in the raw material solution to deposit a solid raw material of the metal gas in the gas generating section; laminating a second glass plate to the second surface of the cell body; The present invention provides a method for manufacturing a metal gas-filled cell, comprising:

[0010] In another aspect, the present invention provides a method for producing a composition comprising: a cell body having a first surface, a second surface, a drip port, and a gas generating portion; a first glass plate bonded to the first surface of the cell body; a second glass plate bonded to the second surface of the cell body; an optical chamber provided in at least one selected from the cell body, the first glass plate, and the second glass plate, the optical chamber communicating with the gas generator; a metal gas sealed in the optical chamber; Equipped with the gas generating section has a plurality of grooves that open to the first surface, the drip port includes a through-hole extending from the first surface to the second surface and communicating with the gas generating unit; A metal gas-filled cell is provided.

[0011] In another aspect, the present invention provides a method for producing a composition comprising: a cell body having a first surface, a drip port, and a gas generating portion; a glass plate bonded to the first surface of the cell body; an optical chamber provided in at least one selected from the cell body and the glass plate and communicating with the gas generating unit; a metal gas sealed in the optical chamber; Equipped with the gas generating section has a plurality of grooves that open to the first surface, the drip port is open to the first surface and communicates with the gas generating unit; A metal gas-filled cell is provided. [Effects of the Invention]

[0012] According to the present invention, metal gas can be generated more efficiently and in a shorter time. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a metal gas sealed cell according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional perspective view of the cell body taken along line II-II in FIG. [Figure 3A] FIG. 3A is a partially enlarged view of the gas generating section. [Figure 3B] FIG. 3B is a partially enlarged view showing another example of the groove structure. [Figure 4A] FIG. 4A is a process diagram showing a method for manufacturing a metal gas filled cell. [Figure 4B] FIG. 4B is a process diagram following FIG. 4A. [Figure 4C] FIG. 4C is a process diagram showing a method for manufacturing a metal gas sealed cell according to a modified example. [Figure 5] FIG. 5 is a diagram showing the process sequence when forming a gas generating portion by deep reactive ion etching. [Figure 6A]FIG. 6A is a diagram schematically showing the operation of the gas generating unit when a raw material solution is introduced into the gas generating unit and the cell body is heated. [Figure 6B] FIG. 6B is a diagram schematically showing the operation of the gas generator when a solid raw material is precipitated using a cell body that is not closed by a first glass plate. [Figure 7] FIG. 7 is a plan view of an assembly including a plurality of metal gas-filled cells. [Figure 8] FIG. 8 is a plan view of a metal gas sealed cell according to the first modification. [Figure 9] FIG. 9 is a plan view of a metal gas sealed cell according to the second modification. [Figure 10] FIG. 10 is a plan view of a metal gas sealed cell according to the third modification. [Figure 11A] FIG. 11A is a plan view (top view) of a metal gas sealed cell according to Modification 4. FIG. [Figure 11B] FIG. 11B is a bottom view of the metal gas sealed cell according to the fourth modification. [Figure 11C] FIG. 11C is a cross-sectional view of a metal gas sealed cell according to Modification 4. As shown in FIG. [Figure 12A] FIG. 12A is a plan view (top view) of a metal gas sealed cell according to Modification 5. FIG. [Figure 12B] FIG. 12B is a bottom view of the metal gas sealed cell according to the fifth modification. [Figure 12C] FIG. 12C is a cross-sectional view of a metal gas sealed cell according to Modification 5. As shown in FIG. [Figure 13A] FIG. 13A is a plan view (top view) of a metal gas sealed cell according to Modification 6. FIG. [Figure 13B] FIG. 13B is a bottom view of the metal gas sealed cell according to the sixth modification. [Figure 13C] FIG. 13C is a cross-sectional view of a metal gas sealed cell according to Modification 6. As shown in FIG. [Figure 14] FIG. 14 is a plan view of a metal gas sealed cell according to the seventh modification. [Figure 15] FIG. 15 is a plan view of a metal gas sealed cell according to the eighth modification. [Figure 16]FIG. 16 is a plan view of a metal gas sealed cell according to the ninth modification. [Figure 17] FIG. 17 is a plan view of a metal gas sealed cell according to the tenth modification. [Figure 18] FIG. 18 is a cross-sectional view of a metal gas sealed cell according to the eleventh modification. [Figure 19] FIG. 19 is a cross-sectional view of a metal gas sealed cell according to the twelfth modification. [Figure 20] FIG. 20 is a cross-sectional view of a metal gas sealed cell according to the thirteenth modification. [Figure 21A] FIG. 21A is a cross-sectional view taken along line AA' of a metal gas sealed cell according to Modification 14. FIG. [Figure 21B] FIG. 21B is a plan view (top view) of a metal gas sealed cell according to Modification 14. As shown in FIG. [Figure 22A] FIG. 22A is a cross-sectional view of a cell body according to Modification 15. FIG. [Figure 22B] FIG. 22B is a plan view of a cell body according to Modification 15. FIG. [Figure 23] FIG. 23 is a cross-sectional view of a metal gas sealed cell according to the sixteenth modification. [Figure 24] FIG. 24 is a plan view of a microchannel having an alternative structure. [Figure 25] FIG. 25 is a perspective view of a metal gas sealed cell according to the second embodiment of the present invention. [Figure 26] FIG. 26 is a cross-sectional view of a metal gas sealed cell according to the seventeenth modification. [Figure 27] FIG. 27 is a graph obtained by normalizing and fitting the absorbance graphs at 60°C, 70°C and 80°C. [Figure 28] FIG. 28 is a cross-sectional SEM image of the gas generating portion of the metal gas sealed cell of the example. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings, but is not limited to the following embodiments.

[0015] (First embodiment) Fig. 1 is a perspective view of a metal gas filled cell 100 according to a first embodiment of the present invention. Fig. 2 is a cross-sectional perspective view of a cell body 10 taken along line II-II in Fig. 1. The metal gas filled cell 100 The cell body 10 has a cell body 10, a first glass plate 11, and a second glass plate 12. The cell body 10 has a first surface 10p and a second surface 10q. The first surface 10p and the second surface 10q are surfaces that face each other. The first surface 10p and the second surface 10q may each be a main surface of the cell body 10. The "main surface" means the surface with the largest area. The first glass plate 11 is bonded to the first surface 10p. The second glass plate 12 is bonded to the second surface 10q.

[0016] In this embodiment, the first glass plate 11 and the second glass plate 12 cover the entire first surface 10p and the entire second surface 10q, respectively. However, this is not essential. The first surface 10p may include a portion that is not covered by the first glass plate 11. The second surface 10q may include a portion that is not covered by the second glass plate 12. This also applies to other embodiments and modified examples described below.

[0017] The metal gas filled cell 100 contains a metal gas and a buffer gas. The metal gas typically contains an alkali metal gas such as K, Rb, or Cs. By filling the alkali metal gas, the metal gas filled cell 100 can function as an atomic oscillator by detecting CPT resonance. The buffer gas may be an inert gas. Examples of the inert gas include H2 gas, N2 gas, rare gases, and mixtures thereof. The buffer gas is not required; only the metal gas may be filled.

[0018] The first glass plate 11 and the second glass plate 12 are each thin glass plates that sufficiently transmit light in a predetermined wavelength band. "Light in a predetermined wavelength band" refers to light that is irradiated when the metal gas sealed cell 100 is actually used. For example, when the metal gas is Cs gas, the light in the predetermined wavelength band is light in the Cs absorption wavelength band (Cs-D1 line, 894.6 nm). "Sufficiently transparent" means, for example, that the transmittance of light in the predetermined wavelength band is 90% or more. Glass plates that can be anodically bonded to the cell body 10 can be used as the first glass plate 11 and the second glass plate 12. Examples of glass that can be anodically bonded to silicon include silicate glass, borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass.

[0019] The cell body 10 is made of, for example, silicon. Using MEMS processing technology, multiple metal gas-filled cells 100 can be manufactured from a single silicon wafer. Because silicon is less reactive with alkali metal gas and buffer gas, a silicon cell body 10 can maintain a stable internal atmosphere in the metal gas-filled cell 100 and a constant vapor pressure of the alkali metal gas. Using a high-quality silicon wafer can also improve the performance of the metal gas-filled cell 100. Furthermore, when the cell body 10 is made of silicon, the first glass plate 11 and the second glass plate 12 can be bonded to the cell body 10 by anodic bonding without using any other bonding material. This also contributes to maintaining a stable internal atmosphere in the metal gas-filled cell 100 and a constant vapor pressure of the alkali metal gas. However, the material of the cell body 10 is not particularly limited. The cell body 10 may be made of a metal such as stainless steel or glass, as long as it is a material that can be micro-machined. The shape of the cell body 10 is also not particularly limited. The cell body 10 may have a plate-like shape in a planar view, a cylindrical shape, or a rectangular parallelepiped shape. The cell body 10 having a rectangular parallelepiped shape means that the polyhedron with the smallest volume that surrounds the cell body 10 is a rectangular parallelepiped. The method of joining the first glass plate 11 and the second glass plate 12 to the cell body 10 is not particularly limited. At least one of the first glass plate 11 and the second glass plate 12 may be bonded to the cell body 10 using a bonding material such as an adhesive, glass frit, or a metal material. The method of joining the cell body 10 and the first glass plate 11 may be different from the method of joining the cell body 10 and the second glass plate 12.

[0020] The cell body 10 has an optical chamber 14, a drip port 16, and a gas generator 20. As described below, the optical chamber 14 may be provided in the first glass plate 11 and / or the second glass plate 12. The optical chamber 14 may be provided in at least one selected from the cell body 10, the first glass plate 11, and the second glass plate 12, and may be a portion that communicates with the gas generator 20.

[0021] The optical chamber 14 is a portion filled with metal gas and serves as a light passage for detecting CPT resonance. The optical chamber 14 is open to at least one of the first surface 10p and the second surface 10q. In this embodiment, the optical chamber 14 is a through-hole extending through the cell body 10 from the first surface 10p to the second surface 10q. The cross-sectional area of ​​the through-hole may be constant or may vary along the thickness direction of the cell body 10. The through-hole serving as the optical chamber 14 is located at the center of the cell body 10. However, as described below, a bottomed hole that opens only to the first surface 10p or the second surface 10q can also be used as the optical chamber. The shape of the optical chamber 14 is not particularly limited. The shape of the optical chamber 14 may be circular, elliptical, or polygonal in plan view. The position of the optical chamber 14 is also not particularly limited, and the optical chamber may be located at a position offset from the center of the cell body 10.

[0022] The drip port 16 is a portion for receiving the metal gas raw material solution. The drip port 16 is a through-hole extending from the first surface 10p to the second surface 10q. By providing the drip port 16 as a through-hole, direct introduction of the raw material solution into the gas generation unit 20 can be avoided, thereby preventing contamination of the first surface 10p of the cell body 10 with the raw material solution. This improves the production yield of the metal gas sealed cell 100. The drip port 16 is separated from the optical chamber 14. The drip port 16 is connected to the gas generation unit 20 directly or indirectly via another channel. The shape of the drip port 16 is not particularly limited. The shape of the drip port 16 in a plan view may be polygonal as shown in the figure, circular, or elliptical. The opening area of ​​the drip port 16 on the first surface 10p is smaller than the opening area of ​​the optical chamber 14. This structure contributes to the miniaturization of the metal gas sealed cell 100. However, the sizes of the optical chamber 14 and the drip port 16 are not particularly limited.

[0023] The gas generation unit 20 is a part that generates a solid metal gas precursor from a metal gas precursor solution and generates metal gas from the solid precursor. The gas generation unit 20 may form at least a portion of the path from the drip port 16 to the optical chamber 14. The gas generation unit 20 has a plurality of grooves 22 that open to the first surface 10p. The plurality of grooves 22 are bottomed grooves. In this embodiment, the gas generation unit 20 has a frame shape that surrounds the optical chamber 14 in a plan view. One end and the other end of the gas generation unit 20 face the drip port 16. In other words, the drip port 16 is provided so as to penetrate a portion of the frame-shaped gas generation unit 20.

[0024] The gas generating unit 20 has a plurality of pillars 24 in addition to a plurality of grooves 22. Specifically, the plurality of grooves 22 extend in a lattice pattern in plan view so that the gas generating unit 20 has a plurality of pillars 24. In this embodiment, the plurality of grooves 22 are formed so that the plurality of pillars 24 are arranged in a staggered pattern. Such a microstructure ensures a sufficient surface area for depositing the solid metal gas raw material. The pillars 24 have a rectangular (typically square) shape in plan view. However, the shape of the pillars 24 is not particularly limited. The shape of the pillars 24 may be a prismatic or cylindrical shape.

[0025] FIG. 3A is a partially enlarged view of the gas generating unit 20. As shown in FIG. 3A, the width of each of the plurality of grooves 22 varies periodically along the thickness direction DR of the cell body 10. The thickness direction DR of the cell body 10 is the direction from the first surface 10p toward the second surface 10q. Each of the plurality of grooves 22 has a portion wider than the opening width W of each of the plurality of grooves 22 on the first surface 10p. Specifically, each of the plurality of grooves 22 includes a plurality of first portions 22a and a plurality of second portions 22b. The first portions 22a are portions where the distance between adjacent pillars 24 is long. The second portions 22b are portions where the distance between adjacent pillars 24 is short. The first portions 22a and the second portions 22b are alternately provided from the first surface 10p toward the second surface 10q. The width W2 of the second portion 22b of the groove 22 is equal to, for example, the opening width W of the groove 22 on the first surface 10p. In this embodiment, seven stages of the first portions 22a are provided along the thickness direction DR. However, the number of the first portions 22a and the second portions 22b is not particularly limited.

[0026] When a solid raw material is generated from a raw material solution of metal gas, the solid raw material adheres to the microstructure that constitutes the gas generating section 20 and tends to remain in the gas generating section 20. In addition, the microstructure of the gas generating section 20 makes the chemical reaction caused by heating the solid raw material, such as CsN3, more efficient. The combined effect of preventing the solid raw materials from scattering during thermal decomposition makes it possible to efficiently generate alkali metal gas through a chemical reaction of the solid raw materials even at low temperatures.

[0027] The width W of the groove 22 on the first surface 10p is, for example, not less than 1 μm and not more than 100 μm. The width W1 of the first portion 22a of the groove 22 is, for example, not less than 5 μm and not more than 200 μm. The width W2 of the second portion 22b of the groove 22 is approximately equal to the width W of the groove 22 on the first surface 10p. The width W1 of the first portion 22a and the width W2 of the second portion 22b may gradually narrow from the first surface 10p toward the second surface 10q. The length L of one side of the pillar 24 on the first surface 10p is, for example, not less than 50 μm and not more than 500 μm.

[0028] However, the relationship between the width W of the groove 22 on the first surface 10p, the width W1 of the first portion 22a of the groove 22, and the width W2 of the second portion 22b of the groove 22 is not particularly limited. FIG. 3B is a partially enlarged view showing another example of the structure of the groove 22. As shown in FIG. 3B, the opening of the groove 22 on the first surface 10p may be expanded in advance by etching, and then reactive ion etching, which will be described later, may be performed to form the first portion 22a and the second portion 22b. In this case, the opening width W of the groove 22 on the first surface 10p is wider than the width W1 of the first portion 22a and wider than the width W2 of the second portion 22b. With this structure, a solid source such as CsN3 is allowed to flow through the opening of the groove 22. Even if the particles are deposited on the surface of the cell body 10, they are unlikely to interfere with the bonding between the cell body 10 and the first glass plate 11.

[0029] As shown in FIGS. 1 and 2 , a microchannel 18 is provided between the optical chamber 14 and the gas generator 20, communicating the two. In this embodiment, each of the multiple grooves opening to the first surface 10p serves as a microchannel 18. The width of the microchannel 18 is, for example, narrower than the width W of the grooves 22 in the gas generator 20. This structure helps prevent the solid or liquid metal gas precursor from being introduced into the optical chamber 14. The width of the microchannel 18 is, for example, 1 μm or more and 30 μm or less. The position of the microchannel 18 is not particularly limited. In this embodiment, the microchannel 18 is provided 180 degrees opposite the drip port 16 with respect to the optical chamber 14. Therefore, the solid or liquid metal gas precursor is less likely to be introduced into the optical chamber 14. The microchannel 18 may be formed of only a single groove.

[0030] Next, a method for manufacturing the metal gas sealed cell 100 will be described.

[0031] 4A and 4B are process diagrams showing a method for manufacturing the metal gas filled cell 100. In detail, Fig. 4A shows a method for manufacturing the cell body 10. Fig. 4B shows a method for manufacturing the metal gas filled cell 100 using the cell body 10.

[0032] As shown in step 1 of FIG. 4A, a masking thin film 30 is formed on one surface of the substrate 10y. The thin film 30 may be a metal thin film such as Cr, Al, or Ni, or a silicon oxide film. The thin film 30 may be formed by a vapor-phase method such as evaporation or sputtering. The substrate 10y is, for example, a silicon wafer. Since multiple metal gas-filled cells 100 can be manufactured from a single substrate 10y, the method of this embodiment has excellent productivity. The silicon wafer used as the substrate 10y may be a polycrystalline wafer or a single-crystal wafer. Using a single-crystal wafer can maintain a more stable internal atmosphere of the metal gas-filled cell 100 and a more constant vapor pressure of the alkali metal gas. Because single-crystal wafers do not have grain boundaries, it is easier to form the microstructure of the gas generation section 20 with high dimensional accuracy. The larger the substrate 10y, the easier it is to mass-produce miniaturized metal gas-filled cells 100.

[0033] Next, as shown in step 2, a resist 32 is applied to the surface of the thin film 30, and the resist 32 is patterned using photolithography. The thin film 30 may be omitted and the resist 32 may be formed directly on the substrate 10y.

[0034] Next, as shown in step 3, a portion of the thin film 30 is removed with an etching solution to expose the surface of the substrate 10y.

[0035] Next, as shown in step 4, the optical chamber 14, the drip port 16, and the gas generating section 20 are formed by deep reactive ion etching. In the embodiment, when preparing the cell body 10, the optical chamber 14, the drip port 16, and the gas generator 20 are formed all at once by deep reactive ion etching. This makes it possible to manufacture the cell body 10 with a small number of steps. When the optical chamber 14 is provided on the first glass plate 11 and / or the second glass plate 12, the drip port 16 and the gas generator 20 are formed in step 4. The microchannel 18 is also formed in step 4.

[0036] When the optical chamber 14, the drip port 16, and the gas generation unit 20 are formed at the same time, unevenness is imparted not only to the gas generation unit 20 but also to the inner peripheral surfaces of the optical chamber 14 and the drip port 16. In contrast, according to the following method, although the number of steps increases, unevenness is less likely to occur on the inner peripheral surfaces of the optical chamber 14 and the drip port 16. That is, the gas generation unit 20 is formed by deep reactive ion etching from one surface (first surface) of the substrate 10y. The optical chamber 14 and the drip port 16 are formed by deep reactive ion etching from the other surface (second surface) of the substrate 10y. By simply digging through the substrate 10y, it is possible to form through-holes with flat inner surfaces as the optical chamber 14 and the drip port 16.

[0037] FIG. 5 is a diagram showing the process sequence for forming the gas generating section 20 by deep reactive ion etching. First, etching using sulfur hexafluoride (SF6) and fluorocarbon ( The grooves are formed by repeating this process several times, and then forming a protective film using CF. Next, a thick protective film 36 is formed on the inner surface of the groove using fluorocarbon. Next, the protective film 36 on the bottom surface of the groove is removed using sulfur hexafluoride, and isotropic etching is performed. By repeating these steps several times, the gas generation section 20 having the microstructure described with reference to FIG. 3A can be formed. Alternative gases such as CHF or CFI may be used instead of fluorocarbon.

[0038] As shown in step 5, the thin film 30 and the resist 32 are removed to obtain the cell body 10.

[0039] Next, as shown in step 6 of FIG. 4B , the first glass plate 11 is bonded to the first surface 10p of the cell body 10 to cover the grooves 22 of the gas generation unit 20 and the drip port 16. In this embodiment, the optical chamber 14 also opens to the first surface 10p, so the first glass plate 11 covers the optical chamber 14, the gas generation unit 20, and the drip port 16. The method for bonding the first glass plate 11 and the cell body 10 is anodic bonding. In anodic bonding, the first glass plate 11 and the cell body 10 are overlapped, and a DC voltage is applied between them while they are heated. The heating temperature is, for example, 150°C or higher and 600°C or lower. The applied voltage is, for example, 200V or higher and 1200V or lower.

[0040] The dimensions of the first glass plate 11 in a plan view may match the dimensions of the first surface 10p of the cell body 10. By bonding the first glass plate 11 to the cell body 10, not only the first surface 10p of the cell body 10 in the portion other than the gas generation unit 20 but also the upper surfaces of the multiple pillars 24 of the gas generation unit 20 are joined to the first glass plate 11.

[0041] Next, as shown in step 7, with the first glass plate 11 positioned vertically below the gas generator 20, the metal gas raw material solution 34a is injected into the drip port 16, and the raw material solution 34a is introduced into the gas generator 20. The raw material solution 34a is injected into the drip port 16 from the side of the second surface 10q. Because the first glass plate 11 serves as the bottom of the gas generator 20, the raw material solution 34a does not overflow from the groove 22.

[0042] The raw material solution 34a is a solution containing a metal compound. The metal compound may be CsN3 or the like. Examples of suitable metal compounds include metal azides such as CsCl and metal halides such as CsCl. The metal compounds are typically alkali metal compounds. In this embodiment, alkali metal gas is generated using a chemical reaction of the alkali metal compound. For example, when the alkali metal is Cs, CsN3 The solution is introduced into the gas generating section 20 of the cell body 10 to precipitate solid CsN3. The solvent in the CsN3 solution may be an inorganic solvent such as water, or an organic solvent such as alcohol, acetone, or acetonitrile. When solid CsN3 is heated in a vacuum, the following chemical reaction occurs: Cs and N2 are produced according to the chemical reaction. Alkali metals are produced by thermal decomposition of metal azides. The method simultaneously generates alkali metal gas and N2 gas, which is a buffer gas, without producing any products that affect the performance of the metal gas filled cell 100, such as the gas pressure inside the cell. It has the advantage of being encapsulated in the body 10.

[0043] 2CsN3 → 2Cs+3N2 (1)

[0044] The alkali metal compound is not limited to a metal azide. For example, as shown in the following formula (2), Cs gas can be generated by reacting CsCl with BaN6. However, the alkali metal generation method by thermal decomposition of metal azide has the advantage that it does not produce by-products other than alkali metals and N2, and the by-products do not affect the gas pressure. It has.

[0045] BaN6+2CsCl → 2Cs+BaCl2+3N2...(2)

[0046] Next, in step 8, the solvent contained in the raw material solution 34a is evaporated, and the solid metal gas raw material 34b is precipitated in the gas generator 20. Specifically, the solvent is evaporated by heating the cell body 10. Heating of the cell body 10 can be achieved by placing the cell body 10 on a hot plate or treating the cell body 10 in a heating furnace.

[0047] FIG. 6A is a diagram schematically illustrating the operation of gas generation unit 20 when raw material solution 34a is introduced into gas generation unit 20 and cell body 10 is heated. Arrows in the diagram indicate the flow of raw material solution 34a and the vapor generated from raw material solution 34a. As shown in FIG. 6A, according to the manufacturing method of this embodiment, groove 22 of gas generation unit 20 is closed by first glass plate 11, so raw material solution 34a does not overflow outside gas generation unit 20. Since solid raw material 34b can be produced from almost the entire amount of injected raw material solution 34a, a sufficient amount of solid raw material 34b can be deposited in gas generation unit 20.

[0048] The heating temperature of the cell body 10 when precipitating the solid raw material 34b in the gas generation unit 20 is, for example, 25°C or higher and 315°C or lower. According to this embodiment, even if the cell body 10 is heated to a relatively high temperature and the raw material solution 34a boils, the raw material solution 34a is unlikely to overflow from the gas generation unit 20. The "heating temperature" is the ambient temperature at which the cell body 10 is placed. When a hot plate is used, the heating temperature is the surface temperature of the hot plate. When a heating furnace is used, the heating temperature is the temperature inside the heating furnace.

[0049] FIG. 6B is a schematic diagram illustrating the operation of the gas generator 20 when depositing the solid source material 34b using a cell body 10 that is not enclosed by the first glass plate 11. When the first glass plate 11 is absent and the groove 22 is open to the outside, the source material solution 34a may overflow from the groove 22. Therefore, an excess amount of the source material solution 34a must be injected into the gas generator 20 in advance. Furthermore, the source material solution 34a must be directly injected into the gas generator 20 using a device such as a micropipette. This process is very cumbersome. Furthermore, the solid source material 34b of the metal gas adheres to the surface of the cell body 10. Because the solid source material 34b interferes with anodic bonding between the first glass plate 11 and the cell body 10, the overflowing solid source material 34b from the gas generator 20 must be removed. Naturally, the amount of solid source material 34b deposited in the gas generator 20 is insufficient. The method of this embodiment can avoid these disadvantages.

[0050] Next, in step 9, the second glass plate 12 is bonded to the second surface 10q of the cell body 10. The dimensions of the second glass plate 12 in a plan view may match the dimensions of the second surface 10q of the cell body 10. The method for bonding the second glass plate 12 and the cell body 10 is also anodic bonding. In anodic bonding, the second glass plate 12 and the cell body 10 are overlapped, and a DC voltage is applied between them while they are heated. The heating temperature is, for example, 150°C or higher and 300°C or lower. The applied voltage is, for example, 200V or higher and 1200V or lower. The process of step 9 is performed in a vacuum or in an inert gas atmosphere such as a rare gas or N2 gas. The degree of vacuum is, for example, , 1×10 -3 Pa or more 1×10 -7 Pa or less.

[0051] Finally, in step 10, metal gas is generated from the solid raw material 34b and introduced into the optical chamber 14. Specifically, the cell body 10 is heated to generate the metal gas from the solid raw material 34b. The cell body 10 can be heated by placing the cell body 10 on a hot plate or by treating the cell body 10 in a heating furnace. The heating temperature of the cell body 10 when generating the metal gas is, for example, 250°C or higher and 400°C or lower. Note that instead of heating the cell body 10, the solid raw material 34b may be decomposed by UV irradiation to generate the metal gas, or the solid raw material 34b may be decomposed by laser light irradiation to generate the metal gas.

[0052] When the cell body 10 is heated to generate metal gas, it is desirable to bond the second glass plate 12 to the second surface 10q of the cell body 10 at a temperature lower than the heating temperature when the cell body 10 is heated to generate metal gas. Specifically, it is desirable to bond the second glass plate 12 to the second surface 10q of the cell body 10 at a temperature lower than the decomposition temperature of the solid raw material 34b. Maintaining the temperature of the cell body 10 below the decomposition temperature of the solid raw material 34b when bonding the second glass plate 12 to the second surface 10q prevents gas generation from the solid raw material 34b and prevents an increase in pressure inside the metal gas-filled cell 100. This prevents damage to the metal gas-filled cell 100. In particular, because the pressure difference between the inside and outside of the metal gas-filled cell 100 tends to be large in a vacuum, it is important to prevent gas generation when bonding the second glass plate 12 to the cell body 10. Furthermore, if the temperature is maintained below the decomposition temperature of the solid source material 34b, there is no need to worry about the alkali metal gas or the scattered solid source material 34b contaminating the bonding surface (second surface 10q) of the anodic bonding.

[0053] Through the above steps, the metal gas cell 100 of this embodiment is obtained. A portion of the solid source material 34b remains undecomposed in the gas generator 20. In other words, the metal gas cell 100 has the solid source material 34b of metal gas attached to the gas generator 20. According to this embodiment, no components or materials other than the solid source material 34b are present inside the metal gas cell 100. Therefore, the internal atmosphere of the metal gas cell 100 can be kept stable, and the vapor pressure of the alkali metal gas can be kept constant. Because the solid source material 34b remains in the gas generator 20, if the vapor pressure of the metal gas in the optical chamber 14 decreases due to deterioration over time, the metal gas can be compensated for by reheating the metal gas cell 100.

[0054] Note that step 10 may be performed immediately before using the metal gas sealed cell 100. In other words, it is conceivable that the manufacturer performs steps up to step 9, and the user performs only step 10.

[0055] FIG. 4C is a process diagram showing a manufacturing method of a metal gas sealed cell 100 according to a modified example. The processes up to step 8 in this modified example have been described with reference to FIGS. 4A and 4B. As shown in step 9a in FIG. 4C, in this modified example, the solid raw material 34b is precipitated in the gas generator 20, and then a metal gas is generated from the solid raw material 34b. Specifically, the cell body 10 is heated to generate the metal gas from the solid raw material 34b. At this time, the second glass plate 12 is placed above the second surface 10q of the cell body 10 so that the generated metal gas contacts the surface of the second glass plate 12 and a metal thin film 37 is deposited on the surface of the second glass plate 12. The arrows in step 9a indicate the flow of the generated metal gas. Step 9a is performed in a vacuum or in an inert gas atmosphere such as a rare gas or N2 gas. The degree of vacuum is , e.g., 1 x 10 -3 Pa or more 1×10 -7 Pa or less.

[0056] Next, as shown in step 10a, the cell body 10 and the second glass plate 12 are heated with N2 gas or the like. The container is placed under an atmosphere of an inert gas 38.

[0057] Next, as shown in step 11a, the second glass plate 12 is bonded to the second surface 10q of the cell body 10. This step is as described with reference to step 9 in Fig. 4B.

[0058] Finally, in step 12a, the cell body 10 is heated to the operating temperature of the metal gas cell 100. This causes the metal gas 39 to be supplied to the optical chamber 14 from the thin metal film 37 on the surface of the second glass plate 12. This modification has the advantages of being able to use a desired inert gas, achieve a desired gas ratio, and seal the optical chamber 14 at an optimal gas pressure.

[0059] FIG. 7 is a plan view of an assembly 200 including multiple metal gas cells 100. Multiple metal gas cells 100 can be obtained from a single silicon wafer. The assembly 200 can be separated into individual metal gas cells 100 by cutting along predetermined cutting lines. The assembly 200 shown in FIG. 7 includes metal gas cells with a different design from the metal gas cells 100 described with reference to FIG. 1. In other words, it is possible to fabricate multiple metal gas cells with different designs on a single silicon wafer using MEMS processing technology. Of course, the assembly 200 may include only metal gas cells 100 with a single design. The step of cutting the assembly 200 may be performed before or after step 10 (FIG. 4B) for generating metal gas. The method of this embodiment allows this selection.

[0060] Several modified examples will be described below. Elements common to the embodiment and the modified examples will be given the same reference numerals, and their description may be omitted. The descriptions of the embodiment and the modified examples may be mutually applied unless there is a technical contradiction. The embodiment and the modified examples may be combined with each other unless there is a technical contradiction.

[0061] (Variation) 8 is a plan view of a metal gas filled cell 102 according to Modification 1. In the metal gas filled cell 102, the cell body 10a has three sets of microchannels 18 each including a plurality of grooves. The gas generating unit 20 has a rectangular frame shape in plan view. A drip port 16 is provided on one side of the rectangular frame. Microchannels 18 are provided at three locations around the periphery of the optical chamber 14 so as to connect each of the other three sides to the optical chamber 14.

[0062] FIG. 9 is a plan view of a metal gas filled cell 104 according to Modification 2. In the metal gas filled cell 104, the cell body 10b has two sets of microchannels 18 and a plurality (two) of drip ports 16. The drip ports 16 are arranged at equal angular intervals around the periphery of the optical chamber 14. In FIG. 9, since there are two drip ports 16, the drip ports 16 are provided at positions of 0 degrees and 180 degrees around the optical chamber 14 in a plan view. The microchannels 18 are provided at positions of 90 degrees and 270 degrees. With this structure, the amount of CsN3 aqueous solution injected into each drip port 16 can be reduced. Therefore, the CsN3 aqueous solution is less likely to leak from the dropping port 16 when heated.

[0063] FIG. 10 is a plan view of a metal gas filled cell 106 according to Modification 3. In the metal gas filled cell 106, the gas generating unit 20a of the cell body 10c includes a first region 40 and a second region 41. The arrangement pattern of the pillars 24 in the first region 40 is different from the arrangement pattern of the pillars 24 in the second region 41. In the example shown in FIG. 10, the pillars 24 in the first region 40 are arranged to form a square lattice. In the second region 41, the pillars 24 are arranged in a staggered pattern. The first region 40 and the second region 41 are arranged in this order on the path from the drip port 16 to the optical chamber 14. By devising the arrangement pattern of the pillars 24, it becomes easier for the solid raw material 34b to precipitate from the metal gas raw material solution 34a, and the decomposition reaction of the solid raw material 34b can be facilitated.

[0064] FIG. 11A is a plan view (top view) of a metal gas filled cell 108 according to Modification 4. FIG. 11B is a bottom view of the metal gas filled cell 108 according to Modification 4. FIG. 11C is a cross-sectional view of the metal gas filled cell 108 according to Modification 4. In the metal gas filled cell 108, the cell body 10d has a microchannel 18 that opens to the second surface 10q. The gas generation unit 20 opens to the first surface 10p. The bottom of the microchannel 18 and the bottom of the gas generation unit 20 communicate with each other inside the cell body 10d. In other words, the sum of the depths of the microchannel 18 and the gas generation unit 20 exceeds the thickness of the cell body 10d. This allows the gas generation unit 20 to communicate with the optical chamber 14 through the microchannel 18. For example, the gas generation unit 20 is formed by deep reactive ion etching from the first surface 10p side. The optical chamber 14, the drip port 16, and the microchannel 18 are formed by deep reactive ion etching from the second surface 10q side, thereby obtaining the cell body 10d.

[0065] FIG. 12A is a plan view (top view) of a metal gas filled cell 110 according to Modification 5. FIG. 12B is a bottom view of the metal gas filled cell 110 according to Modification 5. FIG. 12C is a cross-sectional view of the metal gas filled cell 110 according to Modification 5. In the metal gas filled cell 110, the cell body 10e has microchannels 18 that open to both the first surface 10p and the second surface 10q. That is, in this modification, the microchannels 18 are through-holes. When the optical chamber 14, the drip port 16, and the microchannels 18 are through-holes, the cell body 10e is easy to manufacture.

[0066] FIG. 13A is a plan view (top view) of a metal gas filled cell 112 according to Modification 6. FIG. 13B is a bottom view of the metal gas filled cell 112 according to Modification 6. FIG. 13C is a cross-sectional view of the metal gas filled cell 112 according to Modification 6. In the metal gas filled cell 112, the cell body 10f has a microchannel 18 that opens to the first surface 10p. The depth of the microchannel 18 is, for example, 10 μm or less. The microchannel 18 has a width that is sufficiently wider than its depth. In this modification, the microchannel 18 is a wide, shallow groove.

[0067] Thus, the arrangement and shape of the microchannel 18 are not particularly limited as long as it connects the gas generator 20 and the optical chamber 14. The microchannel may be provided in the first glass plate 11, or may be provided in both the cell body and the first glass plate 11.

[0068] 14 is a plan view of a metal gas filled cell 114 according to Modification 7. In the metal gas filled cell 114, the cell body 10g has a joint 44 located between the drip port 16 and the gas generation unit 20 to connect them. The joint 44 includes, for example, a groove opening in the first surface 10p. As shown in the cell body 10g, the drip port 16 and the gas generation unit 20 may be indirectly connected to each other via the joint 44.

[0069] 15 is a plan view of a metal gas filled cell 116 according to Modification 8. In the metal gas filled cell 116, the microchannel 18 of the cell body 10h communicates with the optical chamber 14 and the gas generator 20 via the drip port 16. By appropriately determining the width and depth of the groove serving as the microchannel 18, it is possible to send the metal gas and buffer gas to the optical chamber 14 while preventing the raw material solution 34a from directly entering the optical chamber 14 from the drip port 16.

[0070] 16 is a plan view of a metal gas filled cell 118 according to Modification 9. In the metal gas filled cell 118, the cell body 10i has an additional chamber 48 located between the microchannel 18 and the gas generating unit 20. The additional chamber 48 is, for example, a through-hole, and liquid or solid CsN3 leaking from the gas generating unit 20 passes through the microchannel 18 and enters the optical chamber. The drip port 16 and the gas generator 20 communicate with each other via a joint 44. As in this modification, the optical chamber 14 does not have to be surrounded by the gas generator 20.

[0071] FIG. 17 is a plan view of a metal gas filled cell 120 according to Modification 10. In the metal gas filled cell 120, the cell body 10j has an optical chamber 141 formed of a bottomed hole. A sloped portion 141p that reflects light is provided at the bottom of the bottomed hole serving as the optical chamber 141. The surface of the sloped portion 141p is a mirror surface. Alternatively, a metal film may be provided on the surface of the sloped portion 141p to increase the reflectivity of light. Light passes through the first glass plate 11 to enter the optical chamber 141, is repeatedly reflected by the sloped portion 141p, and passes through the first glass plate 11 again to proceed to the outside of the metal gas filled cell 120.

[0072] FIG. 18 is a cross-sectional view of a metal gas filled cell 122 according to Modification 11. The metal gas filled cell 122 includes a cell body 10k, a first glass plate 51, and a second glass plate 12. The first glass plate 51 has an optical chamber 14. Metal gas is filled in the optical chamber 14. The optical chamber 14 of the first glass plate 51 is connected to the gas generator 20 via a microchannel 18. The depth of the optical chamber 14 is adjusted so that laser light irradiated in an in-plane direction perpendicular to the thickness direction of the metal gas filled cell 122 can pass through the optical chamber 14. The first glass plate 51 may be a glass cube having a shape such as a rectangular parallelepiped or a cylinder.

[0073] When the thickness direction of the metal gas filled cell 122 is defined as the Z direction, the plane parallel to the first surface 10p and the second surface 10q is the XY plane. By irradiating laser light in both the X-axis direction and the Y-axis direction in the XY plane, the metal gas filled cell 122 can also be used as an atomic magnetometer using an optical pumping method.

[0074] 19 is a cross-sectional view of a metal gas filled cell 124 according to Modification 12. The metal gas filled cell 124 also includes a first glass plate 61 having an optical chamber 14. The first glass plate 61 has a dome-shaped protrusion 61a. The dome-shaped protrusion 61a ensures a space that functions as the optical chamber 14.

[0075] 18 and 19, the term "glass plate" in this specification is not necessarily limited to a glass plate that is thinner than the cell body. The glass plate may also have a protrusion or recess for an optical chamber.

[0076] 20 is a cross-sectional view of a metal gas filled cell 126 according to Modification 13. The metal gas filled cell 126 includes a cell body 10m, a first glass plate 11, and a second glass plate 52. The second glass plate 52 has an optical chamber 14.

[0077] As can be seen from Figures 1, 19, and 20, the position of the optical chamber 14 is not particularly limited. The optical chamber 14 may be provided in at least one selected from the cell body, the first glass plate, and the second glass plate. For example, a portion of the optical chamber 14 may be provided in the first glass plate, and the remainder of the optical chamber 14 may be provided in the cell body. However, when the optical chamber 14 is provided in the cell body 10 (Figure 1), it is easy to thin the metal gas sealed cell 100. The effort required to process the glass plates can also be omitted.

[0078] FIG. 21A is a cross-sectional view taken along line AA' of a metal gas filled cell 128 according to Modification 14. FIG. 21B is a plan view (top view) of a metal gas filled cell 128 according to Modification 14. The metal gas filled cell 128 includes a cell body 10n, a first glass plate 11, and a second glass plate 62. The second glass plate 62 has an optical chamber 14. The optical chamber 14 and the drip port 16 overlap in an in-plane direction parallel to the first surface 10p and the second surface 10q. In this modification, the optical chamber 14 and the drip port 16 overlap on the second surface 10q. When the metal gas filled cell 128 is viewed from above, the drip port 16 is located inside the optical chamber 14. No microchannel is provided in the cell body 10n. The drip port 16 also serves as a path from the gas generator 20 to the optical chamber 14. With this structure, it is possible to omit the microchannel.

[0079] The manufacturing method of the metal gas filled cell 128 is as described with reference to Figures 4A and 4B. That is, the first glass plate 11 is bonded to the first surface 10p of the cell body 10n, and the metal gas raw material solution 34a is injected into the drip port 16 to introduce the raw material solution 34a into the gas generator 20. The solvent contained in the raw material solution 34a is evaporated, and the metal gas solid raw material 34b is precipitated in the gas generator 20. The second glass plate 62 is bonded to the second surface 10q of the cell body 10n. The metal gas is generated from the solid raw material 34b, and the metal gas is introduced into the optical chamber 14.

[0080] FIG. 22A is a cross-sectional view of a cell body 10s according to Modification 15. FIG. 22B is a plan view of the cell body 10s according to Modification 15. The cell body 10s does not have a drip port 16 (FIG. 1), and the optical chamber 14 also serves as the drip port. In other words, it is also possible to introduce the metal gas raw material solution 34a into the gas generator 20 through the optical chamber 14. Because the drip port is omitted, the cell body 10s has a simple structure. The arrows in FIG. 22A indicate the flow of the raw material solution 34a.

[0081] 23 is a cross-sectional view of a metal gas filled cell 130 according to Modification 16. The metal gas filled cell 130 includes a cell body 10t, a first glass plate 71, and a second glass plate 12. In this modification, the microchannel 18 is omitted from the cell body 10t, and instead, the microchannel 18 is provided in the first glass plate 71. However, the microchannel 18 may be provided in both the cell body 10t and the first glass plate 71.

[0082] FIG. 24 is a plan view of a microchannel 81 having another structure. In the example shown in FIG. 24, the width of the microchannel 81 is not constant. The microchannel 81 has a first portion 18a and a second portion 18b. The width of the first portion 18a is narrower than the width of the second portion 18b. This structure makes it easier to prevent the metal gas raw material solution 34a from entering the optical chamber 14. The microchannel 81 may have multiple first portions 18a and multiple second portions 18b.

[0083] The depth of the microchannel is arbitrary. That is, the microchannel may have multiple portions with different depths. For example, in the microchannel 81 shown in FIG. 24, the depth of the first portion 18a may be different from the depth of the second portion 18b.

[0084] (Second embodiment) FIG. 25 is a perspective view of a metal gas cell 300 according to a second embodiment of the present invention. The metal gas cell 300 includes a cell body 310 and a glass plate 11. The cell body 310 has a first surface 10p and a second surface 10q. The glass plate 11 is bonded to the first surface 10p. The cell body 310 includes an optical chamber 141, a drip port 316, and a gas generator 20. The cell body 310 does not have a through-hole. The glass plate 11 is bonded only to the first surface 10p. The optical chamber 141 and the drip port 316 are both bottomed holes that open only to the first surface 10p. The structure of the optical chamber 141 is as described with reference to FIG. 17. The drip port 316 is connected to the gas generator 20. The raw material solution 34a can be supplied to the gas generator 20 through the drip port 316. In this embodiment, it can be said that a part of the gas generating section 20 also serves as the drip port 316 .

[0085] The metal gas filled cell 300 can be manufactured, for example, by the following method.

[0086] First, the cell body 310 is fabricated. Except for the absence of a through-hole, the fabrication method for the cell body 310 is the same as that for the cell body 10 described above. Next, a metal gas raw material solution 34a is injected into the drip port 316, and the raw material solution 34a is introduced into the gas generator 20. The raw material solution 34a may be directly introduced into the gas generator 20 using a device such as a micropipette. Next, the solvent contained in the raw material solution 34a is evaporated, and a solid metal gas raw material 34b is precipitated in the gas generator 20. Next, a glass plate 11 is bonded to the first surface 10p of the cell body 310 by anodic bonding. The glass plate 11 is bonded in a vacuum or in an inert gas atmosphere. Finally, a metal gas is generated from the solid raw material 34b, and the metal gas is introduced into the optical chamber 141.

[0087] FIG. 26 is a cross-sectional view of a metal gas filled cell 302 according to Modification 17. The metal gas filled cell 302 includes a cell body 312 and a glass plate 71. The cell body 312 has a gas generation unit 20. The glass plate 71 is provided with an optical chamber 14. The optical chamber 14 and the gas generation unit 20 overlap in an in-plane direction parallel to the first surface 10p, which is the bonding surface between the cell body 312 and the glass plate 71. In this modification, the optical chamber 14 and the gas generation unit 20 overlap at the first surface 10p. The cell body 312 does not have a microchannel or a drip port. According to this modification, the microchannel and the drip port can be omitted. The second glass plate can also be omitted.

[0088] (others) Other acceptable structures are, for example:

[0089] The optical chamber 14 and the gas generating section 20 may be in direct communication without the microchannel 18. The microchannel 18 is not essential.

[0090] The optical chamber 14, the drip port 16, the microchannel 18, and the gas generator 20 may each be formed by a through-hole. In this case, part of the groove 22 constituting the gas generator 20 is replaced with the through-hole. [Example]

[0091] <Example> The metal gas-filled cell described with reference to FIGS. 1 and 2 was manufactured according to the method described with reference to FIGS. 4A and 4B.

[0092] A Cr thin film was formed as an etching mask on a silicon single crystal wafer substrate using an electron beam deposition system (EB1200, Canon Anelva Corporation). Next, a resist (OFPR-800 54cp, Tokyo Ohka Kogyo Co., Ltd.) was applied by spin coating onto the Cr thin film, and a high-speed maskless etching was performed. Exposure using an exposure device (D-light DL-1000GS / KCH, manufactured by Nano System Solutions) The process was carried out. A resist pattern with openings was formed using a developer (SD-1, manufactured by Tokuyama Corporation). Next, the Cr thin film was etched using a Cr etching solution (Esclean S-24, manufactured by Sasaki Chemical Co., Ltd.) to impart the same pattern as the resist to the Cr thin film. The resist was then removed. Deep etching of the substrate was carried out using a deep reactive ion etching system (RIE-800PB-KU, manufactured by Samco Corporation). After reactive ion etching was completed, the substrate was washed and the Cr thin film used as an etching mask was removed. This resulted in a cell body having an optical chamber, a gas generation unit, a drip inlet, and a microchannel.

[0093] Using a wafer bonding device (WAP-100, Bond Tech Co., Ltd.), the first glass was bonded to the first surface of the cell body. The first and second glass plates were bonded together by anodic bonding. A 0.3 mm thick borosilicate glass plate was used as the first glass plate. Anodic bonding was performed at 400°C and an applied voltage of 1 kV. Next, the cell body was held in position so that the first glass plate was positioned on the bottom, and 4.0 μL of CsN3 aqueous solution was added. The CsN3 solution (Sigma-Aldrich) was injected into the drop port of the cell body and allowed to penetrate into the gas generating section. The concentration of CsN3 in the CsN3 solution was 2.0 mg / μL. Next, the cell body was heated to 80°C. The wafer was placed on a hot plate to evaporate the water from the CsN3 solution. Use, 10 -5 A second glass plate was bonded to the second surface of the cell body by anodic bonding under a vacuum of 0.2 Pa. A borosilicate glass plate with a thickness of 0.3 mm was used as the second glass plate. The anodic bonding was carried out at 250°C and an applied voltage of 1 kV. Before bonding, O2 ions and The second surface of the cell body and the surface of the second glass plate were activated by N2 radicals. The set of the first glass plate, the cell body, and the second glass plate was heated to 330 to 340°C to promote the decomposition reaction of CsN3, generating Cs gas and N2 gas. In this way, the metal gas-filled cell of the example was obtained. The metal gas-filled cell of the example had a square shape in plan view and its dimensions were 8 mm x 8 mm x 2.1 mm.

[0094] [Absorption measurement] Using a UV-Vis-NIR spectrophotometer (V-650, manufactured by JASCO Corporation), the Cs D2 line (852. The metal gas-filled cell of the example was irradiated with light of a wavelength around 894.1 nm, and the absorbance was measured. The measurement was performed by gradually heating the metal gas-filled cell from room temperature to 80°C. The results are shown in Figure 27. Note that CPT resonance occurs at the D1 line (894.6 nm), but in this case, it is sufficient to observe the increase in Cs vapor pressure through the absorption phenomenon, so the measurement was performed at the D2 line.

[0095] Figure 27 is a graph obtained by normalizing and fitting the absorbance graphs at 60°C, 70°C, and 80°C. As shown in Figure 27, the peaks become sharper with increasing temperature, confirming an increase in the Cs vapor pressure inside the metal gas-filled cell.

[0096] When Cs is generated, the entire metal gas sealed cell is heated to about 330℃, which is the temperature at which CsN3 is thermally decomposed. is heated, and a sufficient amount of Cs gas is generated. Therefore, from room temperature to about 80°C, the operating temperature of a Cs atomic clock, the vapor pressure of the Cs gas is saturated vapor pressure. As the temperature of the metal gas-filled cell rises from room temperature to 80°C, the saturated vapor pressure increases, and the vapor pressure of the Cs gas also increases, and the absorbance also increases.

[0097] [Cross-sectional SEM observation] In order to confirm the state of the solid CsN3 remaining in the gas generating section of the metal gas sealing cell of the example, To investigate this, the longitudinal cross section of the metal gas-filled cell was observed using a scanning electron microscope (SEM).

[0098] Fig. 28 is a cross-sectional SEM image of the gas generating part of the metal gas filled cell of the example. As shown in Fig. 28, even after the metal gas filled cell is completed, the gas generating part still contains a solid raw material (CsN3 in the example). The solid raw material was mostly present at the bottom of the grooves that made up the gas generation area. At positions close to the openings of the grooves, the solid raw material was thinly attached to the surface of the pillars. In other words, the solid raw material can be roughly divided into two types: (i) the solid raw material was present on the pillars that were adjacent to each other, filling the bottoms of multiple grooves; and (ii) a second remainder covering the surface of the pillar. [Industrial Applicability]

[0099] The metal gas-filled cell of the present invention is useful for atomic clocks, magnetic sensors, inertial sensors, and the like.

Claims

1. a cell body including a first surface, a second surface, a drip port that is a through-hole extending from the first surface to the second surface, and a gas generator having a plurality of grooves that open to the first surface; a first glass plate attached to the first surface of the cell body; and a cap for the gas generator and the drip port; injecting a metal gas raw material solution into the dripping port while the first glass plate is positioned vertically below the gas generator, and introducing the raw material solution into the gas generator; evaporating a solvent contained in the raw material solution to deposit a solid raw material of the metal gas in the gas generating section; laminating a second glass plate to the second surface of the cell body; A method for manufacturing a metal gas-filled cell, comprising:

2. The gas generating unit has a plurality of pillars. The method for manufacturing the metal gas filled cell according to claim 1 .

3. When preparing the cell body, the gas generating section and the drip port are formed at the same time by deep reactive ion etching. The method for manufacturing the metal gas filled cell according to claim 1 or 2.

4. The cell body is made of silicon. A method for manufacturing a metal gas filled cell according to any one of claims 1 to 3.

5. The raw material solution is a solution containing a metal compound. A method for manufacturing the metal gas filled cell according to any one of claims 1 to 4.

6. generating the metal gas from the solid source material and introducing the metal gas into an optical chamber communicating with the gas generator. A method for manufacturing the metal gas filled cell according to any one of claims 1 to 5.

7. The cell body is heated to 250°C or higher and 400°C or lower to generate the metal gas from the solid raw material. The method for manufacturing the metal gas filled cell according to claim 6.

8. the bonding of the second glass plate to the second surface of the cell body is performed at a temperature lower than the heating temperature of the cell body when the metal gas is generated from the solid source material. A method for manufacturing the metal gas filled cell according to any one of claims 1 to 7.

9. the cell body further comprises an optical chamber opening to at least one of the first surface and the second surface. The method for manufacturing the metal gas filled cell according to claim 1 .

10. a cell body having a first surface, a second surface, a drip port, and a gas generating portion; a first glass plate bonded to the first surface of the cell body; a second glass plate bonded to the second surface of the cell body; an optical chamber provided in at least one selected from the cell body, the first glass plate, and the second glass plate, the optical chamber communicating with the gas generator; a metal gas sealed in the optical chamber; Equipped with the gas generating section has a plurality of grooves that open to the first surface, the drip port includes a through-hole extending from the first surface to the second surface and communicating with the gas generating unit; Metal gas-filled cell.

11. the optical chamber is provided in the cell body and is open to at least one of the first surface and the second surface; The metal gas-filled cell of claim 10.

12. a cell body having a first surface, a drip port, and a gas generating portion; a glass plate bonded to the first surface of the cell body; an optical chamber provided in at least one selected from the cell body and the glass plate and communicating with the gas generating unit; a metal gas sealed in the optical chamber; Equipped with the gas generating section has a plurality of grooves that open to the first surface, the drip port is open to the first surface and communicates with the gas generating unit; Metal gas-filled cell.

13. the optical chamber is provided in the cell body and opens to the first surface; 13. The metal gas-filled cell of claim 12.

14. The gas generating unit further includes a solid source of the metal gas attached thereto.

14. The metal gas-filled cell according to any one of claims 10 to 13.

15. the gas generating portion has a plurality of pillars; the solid source material includes a first remainder that is present across the pillars adjacent to each other so as to fill the bottoms of the plurality of grooves, and a second remainder that covers the surfaces of the pillars; 15. The metal gas-filled cell of claim 14.

16. Further comprising a microchannel communicating between the optical chamber and the gas generating unit.

16. The metal gas-filled cell according to any one of claims 10 to 15.

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