JP2015015278A - Gas cell, method of manufacturing gas cell, atomic oscillator, electronic apparatus, and moving body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a gas cell in which transpiration of the sealed metal is suppressed.SOLUTION: A method of manufacturing a gas cell includes: a step for preparing metal, a base substrate having a bottomed hole opened to a first surface and a substrate for sealing; a step for overlapping the sealing substrate on the first substrate so as to enclose the metal in a hole; a first joining step for having a sealing region surrounding an opening and a joining region surrounding the sealing region and heating and joining the base substrate and the sealing substrate in the joining region; and a second joining step for heating and joining the base substrate and the sealing substrate in the sealing region and sealing the hole.

Description

  The present invention relates to a gas cell, a gas cell manufacturing method, an atomic oscillator using the gas cell, an electronic device, and a moving object.

In recent years, with the advancement of digital networks such as mobile communication networks such as mobile phones and television broadcasting networks, high precision and high accuracy as reference clock sources used to generate clock signals for transmission devices and reference frequencies for broadcasting stations, etc. A stable oscillator is indispensable. As such an oscillator, an atomic oscillator having high oscillation frequency accuracy and stability is often used. In addition, with the miniaturization of communication equipment, demands for miniaturization of mounted atomic oscillators have increased, and there has been a demand for miniaturization of the whole including the photoreaction unit (physical package and its drive circuit unit).
In response to the demand for miniaturization, Patent Document 1 discloses an anodic bonding method in which a substrate including a hole provided with a metal and a sealing substrate for sealing the hole are provided in manufacturing a gas cell constituting a physical package. A method of manufacturing a gas cell is disclosed in which a hole provided with a metal is sealed by bonding or the like.

JP 2009-283526 A

  However, in the gas cell manufacturing method described above, the metal evaporates by the heat generated when the substrate provided with the hole provided with the metal and the sealing substrate that seals the hole are bonded, and the hole is sealed in the hole. There is a risk that the amount of metal will decrease. In addition, there is a problem in that the accuracy of the atomic oscillator in which the gas cell is mounted is lowered due to the reduction of the metal enclosed in the gas cell.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
The method of manufacturing a gas cell according to this application example includes a step of preparing a metal, a base substrate having a bottomed hole opened on the first surface, and a sealing substrate, and a sealing substrate so as to confine the metal in the hole. The step of superimposing on the first surface, and the base substrate include a sealing region surrounding the opening and a bonding region surrounding the sealing region, and the base substrate and the sealing substrate are provided in the bonding region. It includes a first bonding step for heat bonding, and a second bonding step for heat-bonding the base substrate and the sealing substrate in the sealing region and sealing the holes.

According to such a method of manufacturing a gas cell, the sealing substrate is overlapped so as to confine the opening of the hole of the base substrate provided with the metal, and the base substrate and the sealing substrate are bonded in the bonding region by the first bonding step. Join. As a result, a gap is generated between the base region and the sealing substrate that are annularly joined so as to surround the sealing region, between the joint region enclosed in the annularly joined portion and the sealing region. Therefore, the transpiration of the metal caused by the heat generated in the second joining step for sealing the hole can be kept in the gap between the base substrate and the sealing substrate included in the annularly joined joint.
Therefore, the manufacturing method of the gas cell mentioned above can manufacture the highly accurate gas cell which suppressed transpiration of the metal enclosed with a hole.

[Application Example 2]
In the gas cell manufacturing method according to the application example described above, it is preferable that the superimposing step includes a step of arranging a metal in the hole.

  According to such a gas cell manufacturing method, by arranging the metal in the hole in the overlapping step, the metal can be disposed immediately before confining the opening of the hole, and the transpiration of the metal can be suppressed.

[Application Example 3]
In the gas cell manufacturing method according to the application example described above, it is preferable that the first joining step performs joining a plurality of times in the joining region.

  According to such a gas cell manufacturing method, the base substrate and the sealing substrate are bonded a plurality of times so as to surround the sealing region in the bonding region. As a result, a plurality of gaps are formed that are included in the joint portion that is joined in an annular shape so as to surround the sealing region. Therefore, since the volume of the gap in which the metal accompanying the heat generated in the second joining process for sealing the hole evaporates is reduced, the metal evaporation can be further suppressed. Therefore, the manufacturing method of the gas cell mentioned above can manufacture the highly accurate gas cell which suppressed the evaporation of the metal further enclosed with a hole.

[Application Example 4]
In the gas cell manufacturing method according to the application example, the first bonding step is characterized in that bonding is performed continuously from the bonding region toward the sealing region.

  According to such a gas cell manufacturing method, the base substrate and the sealing substrate are continuously bonded in the bonding region. By continuously joining the base substrate and the sealing substrate from the joining region toward the sealing region, the gap between the base substrate and the sealing substrate can be reduced. Also, compared to the case of joining a plurality of times, metal transpiration is further extruded to the sealing region by extruding the metal that has been joined so as to surround the sealing region and evaporated in the gap between the joints. Can be suppressed. Therefore, the manufacturing method of the gas cell mentioned above can manufacture the highly accurate gas cell which suppressed the evaporation of the metal further enclosed with a hole.

[Application Example 5]
In the gas cell manufacturing method according to the application example described above, it is preferable that the base substrate includes a plurality of holes and a step of separating each hole after the second bonding step.

  According to such a method for manufacturing a gas cell, by including a step of separating the bonded base substrate and sealing substrate for each hole, a plurality of gas cells can be simultaneously formed in each step of the manufacturing method. . Therefore, the manufacturing method of the gas cell mentioned above can improve production efficiency.

[Application Example 6]
In the gas cell manufacturing method according to the application example described above, it is preferable that the first bonding step cools at least one of the base substrate and the sealing substrate and performs heat bonding.

  According to such a gas cell manufacturing method, the first bonding step is performed while at least one of the base substrate and the sealing substrate is cooled, thereby further suppressing evaporation of the metal sealed in the hole.

[Application Example 7]
In the gas cell manufacturing method according to the application example described above, it is preferable that the second bonding step is performed by performing heat bonding by cooling at least one of the base substrate and the sealing substrate.

  According to such a gas cell manufacturing method, the second bonding step is performed while cooling at least one of the base substrate and the sealing substrate, thereby further suppressing the evaporation of the metal sealed in the hole.

[Application Example 8]
In the gas cell manufacturing method according to the application example described above, it is preferable to use an anodic bonding method for at least one of the first bonding step and the second bonding step.

  According to such a method for manufacturing a gas cell, by using anodic bonding, a covalent bond is generated between the base substrate and the sealing substrate by electrostatic attraction, and strong bonding can be achieved. Therefore, the gas cell manufacturing method described above can manufacture a gas cell in which leakage of the metal to be sealed is suppressed.

[Application Example 9]
In the gas cell manufacturing method according to the application example, the preparing step includes a step of preparing a base substrate by bonding a substrate having a through-hole and a bottom substrate for closing one end of the through-hole. Is preferred.

  According to such a method of manufacturing a gas cell, the step of preparing the base substrate includes the step of closing the hole and closing the hole and joining the bottom substrate serving as the bottom of the hole. The depth of the hole can be determined according to the thickness of the substrate. Therefore, the volume of the hole surrounded by the bottom substrate serving as the bottom of the hole and the sealing substrate serving as the lid of the hole can be easily made uniform. Therefore, the manufacturing method of the gas cell mentioned above can manufacture a highly accurate gas cell because the volume of the hole in which a metal is enclosed becomes uniform.

[Application Example 10]
The gas cell according to this application example includes a base substrate having a bottomed hole that opens on the first surface, a metal provided inside the hole, and a sealing substrate that is bonded to the first surface so as to close the hole. And.

  According to such a gas cell, the sealing substrate and the base substrate provided with the hole provided with the metal are joined, so that the metal is sealed in the hole and the transpiration of the metal is suppressed. A gas cell can be obtained.

[Application Example 11]
An atomic oscillator according to this application example includes a gas cell in which metal atoms are sealed, a light emitting unit that emits light including resonance light in the gas cell, a light detecting unit that detects light transmitted through the gas cell, and a light detecting unit A gas cell having a bottomed hole opening in the first surface, and a base substrate provided with a metal inside the hole, and closing the hole Thus, a sealing substrate bonded to the first surface is provided.

  In such an atomic oscillator, transpiration of a metal sealed in a manufacturing process of a gas cell constituting the atomic oscillator is suppressed. Therefore, the light emitted from the light irradiator can obtain stable resonance light by passing through the gas cell in which the metal atoms are sealed. Therefore, the atomic oscillator described above can obtain a highly accurate oscillation signal.

[Application Example 12]
An electronic apparatus according to this application example includes the above-described atomic oscillator.

  According to such an electronic device, by providing the above-described atomic oscillator, the electronic device can be operated based on a highly accurate oscillation signal. Therefore, the reliability of the electronic device can be increased.

[Application Example 13]
The moving body according to this application example includes the above-described atomic oscillator.

  According to such a moving body, by providing the above-described atomic oscillator, the moving body can be operated based on a highly accurate oscillation signal. Therefore, the reliability of the electronic device can be increased.

Sectional drawing which shows the gas cell which concerns on 1st Embodiment typically. Process drawing explaining the manufacturing method of the gas cell which concerns on 1st Embodiment. Process drawing explaining the manufacturing method of the gas cell which concerns on 1st Embodiment. The top view explaining the joining process in the manufacturing method of the gas cell concerning a 1st embodiment. Process drawing explaining the manufacturing method of the gas cell which concerns on 2nd Embodiment. Process drawing explaining the manufacturing method of the gas cell which concerns on 2nd Embodiment. Process drawing explaining the preparation process of the base substrate which comprises the gas cell which concerns on 1st and 2nd embodiment. The block diagram explaining the structure of the atomic oscillator which concerns on 3rd Embodiment. The figure explaining the energy level of the metal of the atomic oscillator concerning a 3rd embodiment. The graph explaining the electromagnetic induction transparency phenomenon of the atomic oscillator which concerns on 3rd Embodiment. FIG. 3 is a diagram schematically showing a personal computer as an electronic apparatus according to an example. FIG. 3 is a diagram schematically illustrating a mobile phone as an electronic apparatus according to an example. The figure which shows typically the digital still camera as an electronic device which concerns on an Example. The figure which shows typically the motor vehicle as a moving body which concerns on an Example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure shown below, the size and ratio of each component may be described differently from the actual component in order to make each component large enough to be recognized on the drawing. is there.

[First Embodiment]
A gas cell and a method for manufacturing the gas cell according to the first embodiment will be described with reference to FIGS.
FIG. 1 is a cross-sectional view schematically showing a gas cell according to the first embodiment. 2 and 3 are process explanatory diagrams schematically showing each process of the method of manufacturing the gas cell shown in FIG. FIG. 4 is a plan view for explaining a joining step in the gas cell manufacturing method according to the first embodiment.

The gas cell 100 of the present embodiment is a cell in which a hole 180 provided in a cell substrate 120 is provided with a metal 180, and the hole 122 is sealed by a bottom substrate 140 and a sealing substrate 160. It can be used for the physical package 3.
Below, the structure of the gas cell 100 and the manufacturing method of the gas cell 100 are explained in full detail.

[Structure of gas cell 100]
The gas cell 100 of this embodiment includes a base substrate 130 and a sealing substrate 160 on the first surface of the base substrate 130. The base substrate 130 includes a cell substrate 120 and a bottom substrate 140. A hole 122 is provided in the cell substrate 120 as the base substrate 130, and a metal 180 is provided in the hole 122. A bottom substrate 140 serving as a bottom 123 of the hole 122 is bonded to the cell substrate 120 on a second surface 120b opposite to the first surface 120a to which the sealing substrate 160 is bonded.

(Cell board 120)
The cell substrate 120 is provided with holes so as to penetrate the first surface 120a to which the sealing substrate 160 is bonded and the second surface 120b to which the bottom substrate 140 is bonded. The hole constitutes the hole 122 by connecting the sealing substrate 160 and the bottom substrate 140 to the cell substrate 120. The shape of the hole 122 is not particularly limited. For example, the hole 122 has a polygonal shape or a circular shape. In the present embodiment, the hole 122 has a circular shape as an example. The hole 122 is provided with a size of approximately 2 mm in diameter.
The cell substrate 120 can use a silicon substrate, a glass substrate, or the like as the material. The material constituting the cell substrate 120 is not particularly limited. In the present embodiment, the cell substrate 120 is a silicon substrate having a thickness of about 1 mm to 2 mm as an example.

(Bottom substrate 140)
The bottom substrate 140 is bonded to the second surface 120b of the cell substrate 120 described above. The bottom substrate 140 is provided as a bottom portion 123 of a hole provided in the cell substrate 120.
The bottom substrate 140 can be made of a silicon substrate, a glass substrate, or the like. The material constituting the bottom substrate 140 is not particularly limited. In this embodiment, the bottom substrate 140 is a glass substrate having a thickness of about 0.25 mm as an example.

(Sealing substrate 160)
The sealing substrate 160 is bonded to the first surface 120a of the cell substrate 120 described above. The sealing substrate 160 is provided as a lid portion that seals holes provided in the cell substrate 120.
As the material of the sealing substrate 160, a silicon substrate, a glass substrate, or the like can be used. The material constituting the sealing substrate 160 is not particularly limited. In this embodiment, the sealing substrate 160 uses a glass substrate having a thickness of about 0.25 mm as an example.

(Metal 180)
The metal 180 is provided in the hole 122 sealed by the bottom substrate 140 and the sealing substrate 160.
As the metal 180, a metal having a monovalent cation such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), or the like is used. be able to. In the gas cell 100 of the present embodiment, the metal 180 is not particularly limited. In this embodiment, the metal 180 uses cesium (Cs) as an example.
The metal 180 (such as cesium (Cs)) is liquid at room temperature. Therefore, the metal 180 is sealed so as to accumulate at the bottom 123 of the hole 122.

When used in the atomic oscillator 1 described later in the third embodiment, the gas cell 100 of the present embodiment transmits light into the metal 180 (metal atom) vaporized in the hole 122. Therefore, it is preferable that an amount of the metal 180 that does not prevent light transmission is enclosed in the hole 122.
Note that the metal 180 may react with silicon constituting the cell substrate 120 to generate a compound. Therefore, when there are few metals 180 enclosed with the hole 122, there exists a possibility that the metal 180 may lose | disappear by this reaction. Therefore, it is preferable that a sufficient amount of the metal 180 is not enclosed in the hole 122 so as not to prevent light transmission.

[Method for Manufacturing Gas Cell 100]
The manufacturing process of the gas cell 100 described above will be described.
The steps of manufacturing the gas cell 100 include a step of preparing the base substrate 130, a step of stacking (stacking) the base substrate 130 and the sealing substrate 160, and a bonding step of bonding the base substrate 130 and the sealing substrate 160 together. And including. Hereinafter, the manufacturing method of the gas cell 100 is demonstrated in order of a process.

(Base substrate preparation process)
FIG. 2A shows a state in which the cell substrate 120 and the bottom substrate 140 are bonded and the base substrate 130 is prepared. FIG. 2B shows a state in which the metal 180 is placed in the recess 125 provided in the base substrate 130.
The base substrate preparation step is a step of preparing the base substrate 130 in which the cell substrate 120 and the bottom substrate 140 are bonded. The base substrate preparation step is a step of placing a metal 180 such as cesium (Cs) in the recess 125.
In the base substrate preparation step, a base substrate 130 in which the bottom substrate 140 and the cell substrate 120 including the holes 122 are bonded is prepared. Further, the bottom substrate 140 and the cell substrate 120 are bonded to each other, so that a concave portion 125 including a hole 122 and a bottom portion 123 is provided. The recess 125 has an opening on the first surface 120a side to which the sealing substrate 160 is bonded, and a bottom 123 on the second surface 120b side.

Next, in the base substrate preparation step, a metal 180 such as cesium (Cs) is placed in the recess 125. In the base substrate preparation step, the method for placing the metal 180 is not particularly limited. The placement of the metal 180 is preferably performed in a space that has been decompressed using, for example, a dispenser device.
In the following description, the base substrate 130 will be described as including the cell substrate 120 and the bottom substrate 140.

(Sealing substrate lamination process)
FIG. 2C shows a state in which the sealing substrate 160 is superimposed on the base substrate 130 on which the metal 180 is placed.
In the sealing substrate stacking step, the sealing substrate 160 serving as a lid for sealing the metal 180 provided in the recess 125 of the base substrate 130 is applied to the first surface 120 a of the cell substrate 120 constituting the base substrate 130. This is a process of overlapping (stacking). The metal 180 can be confined in the hole 122 by overlaying the sealing substrate 160 on the base substrate 130.
The method for laminating (overlapping) the sealing substrate 160 on the first surface 120a (base substrate 130) of the cell substrate 120 is not particularly limited. It is preferable to perform the sealing substrate lamination process of this embodiment, for example in the pressure-reduced space.

(Joining process)
The bonding process is a process of bonding the base substrate 130 and the sealing substrate 160 together. The joining process includes a first joining process and a second joining process described later.
The base substrate 130 to be bonded to the sealing substrate 160 in the bonding process includes a sealing region 134 set around the hole 122 on the first surface 120a of the cell substrate 120, and the first surface 120a of the cell substrate 120. Thus, a virtual region of the bonding region 132 in contact with the sealing region 134 is set.
The sealing region 134 indicates a region left as the gas cell 100. In addition, the bonding region 132 indicates a region where the base substrate 130 and the sealing substrate 160 are bonded to seal the hole 122 with the sealing substrate 160, and is a portion that is cut out in an individualization process to be described later. Become.

The first bonding step is a step of bonding the sealing substrate 160 and the first surface 120 a of the cell substrate 120 constituting the base substrate 130 in the bonding region 132.
The second bonding step is a step of bonding the sealing substrate 160 and the first surface 120 a of the cell substrate 120 constituting the base substrate 130 in the sealing region 134.

FIG. 2D shows a state in which the sealing substrate 160 is bonded to the first surface 120a of the cell substrate 120 constituting the base substrate 130 by the first bonding step.
In the first bonding step, the cell substrate 120 and the sealing substrate 160 are bonded in the bonding region 132 which is a virtual region set on the first surface 120a.
In the first bonding step, a heat bonding method can be used as the bonding method. In the manufacturing method of the gas cell 100 of the present embodiment, the cell substrate 120 and the sealing substrate 160 are bonded using an anodic bonding method as an example of heat bonding.

In joining the cell substrate 120 and the sealing substrate 160 using the anodic bonding method, first, the base substrate 130 and the sealing substrate 160 to be joined are placed in a reduced-pressure nitrogen atmosphere, and the cell substrate 120 and the sealing substrate 160 are sealed. The joint 152 where the stop substrate 160 is joined and the vicinity thereof are heated (approximately 300 ° C. to 400 ° C.). Further, an electrode is brought into contact with the base substrate 130 and the sealing substrate 160 (bonding portion 152), and a voltage (approximately 800 V) is applied between both the substrates to be bonded.
As a result, the base substrate 130 and the sealing substrate 160 are covalently bonded by electrostatic attraction on the first surface 120a of the cell substrate 120 to be bonded (the interface between the base substrate 130 and the sealing substrate 160), and are firmly attached to each other. To be joined.

More specifically, the sealing substrate 160 (borosilicate glass) contains an alkali metal element (movable element) such as sodium (Na). These movable elements (Na ions) can freely move in the sealing substrate 160. If any of SiO ₂ constituting the sealing substrate 160 has a defect (missing) of an element, it has a charge of SiO − and is electrically neutral while paired with a movable element.
When the sealing substrate 160 having such characteristics is heated and a negative voltage (potential) is applied to the sealing substrate 160 through the electrode under the condition that the movable element is easy to move, the movable element is placed on the side where the electrode is provided. Moving. In the junction 152 which is a bonding surface (first surface 120a) between the sealing substrate 160 and the cell substrate 120 including silicon, a SiO-depletion layer (a layer depleted in Na ions) is formed on the sealing substrate 160 side. ) Is formed. In addition, a layer in which positive charges are collected is formed on the first surface 120 a of the cell substrate 120.
As a result, the electrostatic attractive force is generated at the interface (bonding portion 152) between the first surface 120a of the cell substrate 120 constituting the base substrate 130 and the sealing substrate 160, whereby the covalent bond is generated, and the base substrate 130 (cell The substrate 120) and the sealing substrate 160 are joined.

  In the first bonding step, the sealing substrate 160 and the first surface 120 a of the cell substrate 120 are bonded in an annular shape so as to surround the hole 122. In other words, the cell substrate 120 and the sealing substrate 160 are bonded by the bonding portion 152 so as to surround the sealing region 134.

FIG. 3E shows a state in which the cell substrate 120 and the sealing substrate 160 constituting the base substrate 130 are bonded by the second bonding step, and the hole 122 provided in the cell substrate 120 is sealed by the sealing substrate 160. Show.
In the second bonding step, the cell substrate 120 and the sealing substrate 160 are bonded in the sealing region 134.
In the second bonding step, a heat bonding method can be used as a bonding method between the cell substrate 120 and the sealing substrate 160. In the manufacturing method of the gas cell 100 of the present embodiment, the cell substrate 120 and the sealing substrate 160 are bonded using an anodic bonding method as an example of the heat bonding as in the first bonding step.

  In the second bonding step, the sealing substrate 160 and the first surface 120 a of the cell substrate 120 are bonded in an annular shape so as to surround the hole 122. In other words, the cell substrate 120 and the sealing substrate 160 are bonded by the bonding portion 154 so as to surround the hole 122 in the sealing region 134.

Here, the bonding step is required to bond the base substrate 130 and the sealing substrate 160 so that the metal 180 sealed in the recess 125 (hole 122) does not evaporate. Therefore, the joining process uses a heat joining method that provides a strong joining force. In the heat bonding method, since heat is applied to the base substrate 130 and the sealing substrate 160 that are objects to be bonded, the heat may be transferred to the metal 180 and evaporated.
Therefore, in the method for manufacturing the gas cell 100 of the present invention, the first bonding step is performed in the bonding region 132 that is separated from the hole 122 in which the metal 180 is enclosed, and heat from the bonding is prevented from being transmitted to the metal 180. Further, in the first bonding step, the base substrate 130 and the sealing substrate 160 are bonded in an annular shape so as to surround the sealing region 134 by the bonding portion 152. Accordingly, the sealing region 134 and the bonding region 132 included in the bonding portion 154 that is circularly bonded between the base substrate 130 and the sealing substrate 160 that are bonded in an annular shape so as to surround the sealing region 134. , A gap C is generated. Therefore, the transpiration (steam) of the metal 180 accompanying the heat generated in the second joining step for sealing the hole 122 can be retained in the gap C.

In the first bonding step described above, the base substrate 130 and the sealing substrate 160 are bonded by the bonding portion 152 so as to surround the sealing region 134. In order to suppress the damage of 160, it may be divided and joined.
For example, as shown in FIG. 4 (d11), first, the base substrate 130 and the sealing substrate 160 are joined together at the joining portion 152y along the first direction, and then, as shown in FIG. 4 (d12). The base substrate 130 and the sealing substrate 160 may be joined by the joining portion 152x along a second direction that intersects the first direction.

  In the first bonding step and the second bonding step, heat bonding may be performed while cooling at least one of the base substrate 130 and the sealing substrate 160. Although the cooling method of the base substrate 130 and the sealing substrate 160 is not particularly limited, for example, a metal plate (heat radiator) having a large specific heat is disposed so as to contact the periphery of the joint portions 152 and 154, and the base substrate 130 being joined. And the sealing substrate 160 can be cooled. By cooling the base substrate 130 and the sealing substrate 160, it is possible to suppress the heat accompanying the joining to the metal 180 and to suppress the evaporation of the metal 180.

  In the first bonding step and the second bonding step, an anodic bonding method is used as an example of heat bonding, but the eutectic bonding, glass bonding, glass frit bonding, direct bonding, and resin are not limited to the anodic bonding method. Bonding, adhesive bonding, or the like may be used.

(Individualization process)
Returning to FIG. 3, each step of the method for manufacturing the gas cell 100 will be described.
FIG. 3F shows a state in which the base substrate 130 and the sealing substrate 160 are joined by the joining process described above, and the metal 180 is sealed in the hole 122.
The singulation process is a process of cutting the base substrate 130 and the sealing substrate 160 bonded in the bonding process into individual gas cells 100.
In the separation process, a dicing line DL is set between the bonding portion 154 where the base substrate 130 and the sealing substrate 160 are bonded in the sealing region 134 and the bonding region 132, and along the dicing line DL. The gas cell 100 is singulated.

FIG. 3G shows a state in which the gas cell 100 is singulated by the above-described singulation process.
Each process of the manufacturing method of the gas cell 100 completes a series of manufacturing processes by completing the above-described individualization process.

According to the first embodiment described above, the following effects can be obtained.
According to such a manufacturing method of the gas cell 100, the base substrate 130 and the sealing substrate 160 are first bonded in the bonding region 132 so as to surround the sealing region 134 that seals the hole 122 provided with the metal 180. Bonding is performed according to the process. Thereby, between the base substrate 130 and the sealing substrate 160 that are annularly bonded so as to surround the sealing region 134, the bonding region 132 and the sealing region 134 that are included in the bonding portion 152 that is bonded annularly. A gap C occurs in
Therefore, the transpiration of the metal 180 caused by the heat generated in the second bonding step for sealing the hole 122 can be kept in the gap C between the base substrate 130 and the sealing substrate 160 enclosed in the annularly bonded bonding portion 152. it can. Therefore, the manufacturing method of the gas cell 100 of this embodiment can manufacture the highly accurate gas cell 100 which suppressed the evaporation of the metal 180 enclosed in the hole 122.

[Second Embodiment]
The manufacturing method of the gas cell 100 which concerns on 2nd Embodiment is demonstrated using FIG. 5 and FIG. FIG. 5 and FIG. 6 are diagrams for explaining a joining step among the steps of the method for manufacturing the gas cell 100 according to the second embodiment.

  The method for manufacturing the gas cell 100 according to the second embodiment differs from the method for manufacturing the gas cell 100 described in the first embodiment in the joining process. Since the manufacturing process of the other gas cell 100 and the configuration of the gas cell 100 are the same, the same reference numerals and reference numerals are given to the same configuration, and the description will be partially omitted.

(Joining process)
In the manufacturing process of the gas cell 100 according to the second embodiment, the joining process includes a first joining process and a second joining process.
FIG. 5 shows an example in which the base substrate 130 and the sealing substrate 160 are bonded a plurality of times in the bonding region 132 as an example of the first bonding process. FIG. 6 shows an example in which the base substrate 130 and the sealing substrate 160 are bonded continuously in the bonding region 132 as an example of the first bonding step.

FIG. 5D11 shows a state in which the sealing substrate 160 is bonded to the first surface 120a of the cell substrate 120 constituting the base substrate 130 by the first bonding process.
The first bonding step of the present embodiment is a step of bonding the sealing substrate 160 and the first surface 120a of the cell substrate 120 in the bonding region 132, and the method for manufacturing the gas cell 100 described above in the first embodiment. Is substantially the same.

  In the first bonding step, the sealing substrate 160 and the first surface 120a of the cell substrate 120 are bonded a plurality of times. In the first bonding step of the present embodiment, for example, the sealing substrate 160 and the first surface 120a of the cell substrate 120 are bonded by the bonding portion 152a in the bonding region 132 as the first bonding. Further, as the second bonding, the bonding portion 152 b bonds the sealing substrate 160 and the first surface 120 a of the cell substrate 120 between the previous bonding portion 152 a and the hole 122 in the bonding region 132. Note that the cell substrate 120 and the sealing substrate 160 are bonded to each other by the bonding portions 152 a and 152 b in a ring shape so as to surround the hole 122. In other words, the cell substrate 120 and the sealing substrate 160 are bonded by the bonding portions 152 a and 152 b so as to surround the sealing region 134.

In FIG. 5D12, the sealing substrate 160 and the cell substrate 120 constituting the base substrate 130 are bonded by the second bonding step, and the hole 122 provided in the cell substrate 120 is sealed by the sealing substrate 160. Indicates the state.
The second bonding step is a step of bonding the sealing substrate 160 and the first surface 120a of the cell substrate 120 in the sealing region 134. In the second bonding step, the cell substrate 120 and the sealing substrate 160 are bonded in the sealing region 134.

  In the second bonding step, the sealing substrate 160 and the first surface 120 a of the cell substrate 120 are bonded in an annular shape so as to surround the hole 122. In other words, the cell substrate 120 and the sealing substrate 160 are bonded by the bonding portion 154 so as to surround the hole 122 in the sealing region 134.

  In the first bonding step and the second bonding step of the present embodiment, a heat bonding method can be used as a bonding method between the cell substrate 120 and the sealing substrate 160. In the manufacturing method of the gas cell 100 of this embodiment, the cell substrate 120 and the sealing substrate 160 are joined using the anodic bonding method similarly to 1st Embodiment as the example.

  The first bonding step of the present embodiment described above is not limited to the number of times of bonding, and may be performed n times (integer multiples) three or more times. Moreover, although the 1st joining process of this embodiment mentioned above is performed as multiple times of point joining (joining part 152a, 152b), it is good also as continuous surface joining.

  FIG. 6D21 shows a state in which the sealing substrate 160 and the first surface 120a of the cell substrate 120 constituting the base substrate 130 are surface-bonded by the first bonding step. In the surface bonding between the sealing substrate 160 and the base substrate 130, the portion to be bonded (bonding portion 152r) is heated when the anodic bonding method is used, the electrode is brought into contact with the base substrate 130, and the roller electrode 220 is sealed. A potential is applied to both substrates while pressing against the stationary substrate 160. In the first bonding step, the roller electrode 220 is rotated on the bonding region 132 toward the sealing region 134, so that the sealing substrate 160 and the first surface 120a of the cell substrate 120 are surface-contacted by the bonding portion 152r. Can be combined.

6D22, the sealing substrate 160 and the cell substrate 120 constituting the base substrate 130 are bonded by the second bonding process, and the hole 122 provided in the cell substrate 120 is sealed by the sealing substrate 160. Indicates the state.
Since the second joining step is the same as each joining step described above, description thereof is omitted.

By the way, in the manufacturing method of the gas cell 100, the joining step is required to suppress the evaporation of the metal 180 sealed in the hole 122.
Therefore, in the first bonding process of the present embodiment, the first bonding is performed on the bonding region 132 separated from the hole 122 in which the metal 180 is sealed, and the bonding portion 152a and the sealing region are formed by the first bonding. The second bonding is performed with the 134.
Thereby, the volume of the gap | interval C which the metal 180 evaporates with the heat | fever at the time of sealing the hole 122 at a 2nd joining process can be decreased. Further, in the case of surface bonding using the roller electrode 220, the metal 180 vapor staying in the gap C between the base substrate 130 and the sealing substrate 160 can be bonded while being extruded into the hole 122.

  Since the other manufacturing method and configuration of the gas cell 100 are substantially the same as those in the first embodiment, description thereof is omitted.

According to the second embodiment described above, the following effects can be obtained.
According to such a manufacturing method of the gas cell 100, the base substrate 130 and the sealing substrate 160 are bonded a plurality of times so as to surround the sealing region 134 in the bonding region 132. As a result, a plurality of gaps C included in the joining portions 152a and 152b joined in an annular shape so as to surround the sealing region 134 are formed. Therefore, the volume of the gap C in which the metal 180 that evaporates with the heat generated in the second joining step for sealing the hole 122 can be reduced, so that the evaporation of the metal 180 can be suppressed.
In addition, the base substrate 130 and the sealing substrate 160 are continuously surface-bonded from the bonding region 132 toward the sealing region 134, so that the metal 180 staying in the gap C between the base substrate 130 and the sealing substrate 160. The above can be extruded into the sealing region 134.
Therefore, the above-described method for manufacturing the gas cell 100 can manufacture a highly accurate gas cell in which the evaporation of the metal 180 enclosed in the hole 122 is further suppressed.

In the above-described method for manufacturing the gas cell 100 according to the first embodiment and the second embodiment, the embodiment is described in which the base substrate 130 in which the cell substrate 120 and the bottom substrate 140 are bonded in advance is used in the base substrate preparation process. However, the present invention is not limited to this.
A cell substrate 120 provided with a hole 122 shown in FIG. 7 (a1) and a bottom substrate 140 shown in FIG. 7 (a2) are prepared, and the bottom substrate 140 is placed on the cell substrate 120 as shown in FIG. 7 (a3). The base substrate 130 may be formed and prepared including a step of bonding the substrate.
By including the step of bonding the cell substrate 120 having the hole 122 and the bottom substrate 140 that becomes the bottom 123 of the hole 122, the depth of the hole 122 can be determined according to the thickness of the cell substrate 120. Therefore, the volume of the hole 122 surrounded by the bottom substrate 140 serving as the bottom 123 of the hole 122 and the sealing substrate 160 serving as the lid of the hole 122 can be easily made uniform. Therefore, the manufacturing method of the gas cell 100 mentioned above can manufacture a highly accurate gas cell because the volume of the hole 122 in which the metal 180 is enclosed becomes uniform.

[Third Embodiment]
An atomic oscillator according to a third embodiment will be described with reference to FIGS.
FIG. 8 is a block diagram showing the structure of the atomic oscillator according to the third embodiment. FIG. 9 is a diagram for explaining the energy level of the metal sealed in the gas cell mounted on the atomic oscillator. FIG. 10 is a graph for explaining an electromagnetically induced transparency phenomenon in an atomic oscillator.
The atomic oscillator 1 according to the third embodiment is equipped with the gas cell 100 described above in the first embodiment and the second embodiment. Hereinafter, the atomic oscillator 1 on which the gas cell 100 is mounted will be described.

[Structure of atomic oscillator 1]
An atomic oscillator 1 shown in FIG. 8 is an atomic oscillator using a quantum interference effect.
As shown in FIG. 8, the atomic oscillator 1 includes a first unit 2 (light emitting side unit) provided with a light emitting unit 21, a second electronic component on which a gas cell 100, a light detecting unit 32, and the like are mounted. The second unit 3 (light detection side unit) and the control unit 7 that controls the light emitting unit 21 and the like based on the signal detected by the light detection unit 32.

Here, as shown in FIG. 8, the first unit 2 includes a light emitting portion 21 and a first package 22 (light emitting side package) that houses the light emitting portion 21.
The second unit 3 includes a gas cell 100, a light detection unit 32, a heater 33, a temperature sensor 34, a coil 35, and a second package 36 (light detection side package) that houses these.

The first unit 2 and the second unit 3 are electrically connected to the control unit 7 via wiring (not shown), and are driven and controlled by the control unit 7.
The control unit 7 controls the light emitting unit 21 based on a signal from the temperature control unit 72 that controls the heater provided in the second unit 3, the magnetic field control unit 73 that controls the coil 35, and the light detection unit 32. And an excitation light control unit 71 for performing the above.

[Principle of atomic oscillator 1]
The principle of the atomic oscillator 1 will be briefly described.
In the atomic oscillator 1, the metal 180 sealed in the gas cell 100 is vaporized, and light is transmitted through the metal 180 to operate the atomic oscillator 1. The metal 180 is vaporized by heating with the heater 33.

  As shown in FIG. 9, the metal 180 has an energy level of a three-level system, and has three states of two ground states (ground states α and β) having different energy levels and an excited state. Can take. Here, the ground state α is an energy state lower than the ground state β. When the vaporized metal 180 is irradiated with the first resonance light 1 and the second resonance light having different frequencies on the vaporized metal 180, the frequency ω1 of the first resonance light and the frequency ω2 of the second resonance light are obtained. The light absorptance (light transmittance) of the first resonance light 1 and the second resonance light in the metal 180 changes according to the difference (ω1-ω2).

  When the difference (ω1−ω2) between the frequency ω1 of the first resonant light 1 and the frequency ω2 of the second resonant light coincides with the frequency corresponding to the energy difference between the ground state α and the ground state β, Each excitation from β to the excited state stops. At this time, both the first resonance light 1 and the second resonance light are transmitted without being absorbed by the metal 180. Such a phenomenon is called a CPT phenomenon or an electromagnetically induced transparency (EIT) phenomenon.

  The light emitting unit 21 emits two types of light (first resonance light and second resonance light) having different frequencies as described above toward the gas cell 100. For example, when the light emitting unit 21 fixes the frequency ω1 of the first resonance light and changes the frequency ω2 of the second resonance light, the difference between the frequency ω1 of the first resonance light and the frequency ω2 of the second resonance light. When (ω1-ω2) coincides with the frequency ω0 corresponding to the energy difference between the ground state α and the ground state β, the detection intensity S of the light detection unit 32 increases sharply as shown in FIG. Such a steep signal is detected as an EIT signal. This EIT signal has an eigenvalue determined by the type of metal 180. Therefore, by using such an EIT signal as a reference, a highly accurate atomic oscillator 1 can be realized.

According to the third embodiment described above, the following effects can be obtained.
According to such an atomic oscillator 1, since loss due to evaporation of the metal 180 enclosed in the manufacturing process of the gas cell 100 constituting the atomic oscillator 1 is suppressed, stable resonance light (EIT signal) can be obtained. Can do. Therefore, the atomic oscillator 1 described above can oscillate a highly accurate signal.

(Example)
An example in which the atomic oscillator 1 using the gas cell 100 according to an embodiment of the present invention is applied will be described with reference to FIGS.

[Electronics]
An electronic apparatus to which the atomic oscillator 1 according to an embodiment of the present invention is applied will be described with reference to FIGS.

  FIG. 11 is a perspective view showing an outline of a configuration of a laptop (or mobile) personal computer as an electronic apparatus including the atomic oscillator 1 according to the embodiment of the present invention. In this figure, a laptop personal computer 1100 includes a main body portion 1104 provided with a keyboard 1102 and a display unit 1106 provided with a display portion 1008. The display unit 1106 has a hinge structure portion with respect to the main body portion 1104. It is supported so that rotation is possible. In such a laptop personal computer 1100, an atomic oscillator 1 used as a clock signal for the operation of the laptop personal computer 1100 is mounted. Such an atomic oscillator 1 can obtain stable resonance light because loss due to evaporation of the metal 180 enclosed in the manufacturing process of the gas cell 100 constituting the atomic oscillator 1 is suppressed. Therefore, a highly accurate signal can be oscillated. Therefore, a highly reliable laptop personal computer 1100 can be obtained by mounting the above-described atomic oscillator 1.

  FIG. 12 is a perspective view schematically illustrating a configuration of a mobile phone (including PHS) as an electronic apparatus including the atomic oscillator 1 according to the embodiment of the invention. In this figure, a cellular phone 1200 includes a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206, and a display unit 1208 is disposed between the operation buttons 1202 and the earpiece 1204. In such a cellular phone 1200, an atomic oscillator 1 is mounted as an oscillator of a clock signal that is a reference for communication and operation of the cellular phone 1200. Such an atomic oscillator 1 can obtain stable resonance light because loss due to evaporation of the metal 180 enclosed in the manufacturing process of the gas cell 100 constituting the atomic oscillator 1 is suppressed. Therefore, a highly accurate signal can be oscillated. Therefore, a highly reliable mobile phone 1200 can be obtained by mounting the atomic oscillator 1 described above.

FIG. 12 is a perspective view schematically illustrating a configuration of a digital still camera as an electronic apparatus including the atomic oscillator 1 according to an embodiment of the present invention. In this figure, connection with an external device is also simply shown. Here, an ordinary camera sensitizes a silver halide photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an image sensor such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.
A display unit 1308 is provided on the back of a case (body) 1302 in the digital still camera 1300, and is configured to perform display based on an imaging signal from the CCD. The display unit 1308 displays an object as an electronic image. Functions as a viewfinder. A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side (the back side in the drawing) of the case 1302.
When the photographer confirms the subject image displayed on the display unit 1308 and presses the shutter button 1306, the CCD image pickup signal at that time is transferred and stored in the memory 1310. In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the drawing, a liquid crystal display 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the input / output terminal 1314 for data communication as necessary. Further, the imaging signal stored in the memory 1310 is output to the liquid crystal display 1430 or the personal computer 1440 by a predetermined operation. In such a digital still camera 1300, an atomic oscillator 1 serving as a clock signal for the operation is mounted. Such an atomic oscillator 1 can obtain stable resonance light because loss due to evaporation of the metal 180 enclosed in the manufacturing process of the gas cell 100 constituting the atomic oscillator 1 is suppressed. Therefore, a highly accurate signal can be oscillated. Therefore, a highly reliable digital still camera 1300 can be obtained by mounting the above-described atomic oscillator 1.

  The atomic oscillator 1 according to an embodiment of the present invention includes, for example, an inkjet in addition to the laptop personal computer (mobile personal computer) in FIG. 11, the mobile phone in FIG. 12, and the digital still camera in FIG. Dispenser (eg inkjet printer), TV, video camera, video tape recorder, car navigation device, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone , Crime prevention TV monitor, electronic binoculars, POS terminal, medical equipment (for example, electronic thermometer, blood pressure monitor, blood glucose meter, electrocardiogram measuring device, ultrasonic diagnostic device, electronic endoscope), fish detector, various measuring devices, instruments (Eg, vehicle, aircraft, ship instrumentation), It can be applied to electronic devices such as site simulator.

[Moving object]
FIG. 14 is a perspective view schematically showing an automobile as an example of a moving body. In an automobile 1500, an atomic oscillator 1 that functions as an acceleration sensor is mounted on various control units. For example, as shown in the figure, an automobile 1500 as a moving body includes an electronic control unit (ECU) 1508 that incorporates a sensor that detects the acceleration of the automobile 1500 and controls the output of the engine. 1507. Since the atomic oscillator 1 capable of obtaining a high-accuracy clock signal is mounted on the electronic control unit 1508, the engine output control suitable for the attitude of the vehicle body 1507 is executed with high accuracy, and the consumption of fuel and the like is suppressed. It is possible to obtain an automobile 1500 as a typical mobile body.
In addition, the atomic oscillator 1 can be widely applied to a vehicle body posture control unit, an antilock brake system (ABS), an air bag, and a tire pressure monitoring system (TPMS).
Such an atomic oscillator 1 can obtain stable resonance light because loss due to evaporation of the metal 180 enclosed in the manufacturing process of the gas cell 100 constituting the atomic oscillator 1 is suppressed. Therefore, a highly accurate signal can be oscillated. Therefore, by mounting the above-described atomic oscillator 1, a highly reliable automobile 1500 can be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Atomic oscillator, 100 ... Gas cell, 120 ... Cell board | substrate, 120a ... 1st surface, 120b ... 2nd surface, 122 ... Hole, 123 ... Bottom part, 125 ... Recessed part, 130 ... Base substrate, 132 ... Bonding region, 134 ... Sealing area, 140 ... bottom substrate, 152 ... bonding part, 154 ... bonding part, 160 ... sealing substrate, 180 ... metal, 220 ... roller electrode, 1100 ... laptop personal computer, 1200 ... mobile phone, 1300 ... digital Still camera, 1500 ... car.

Claims (13)

Preparing a metal, a base substrate having a bottomed hole opening in the first surface, and a sealing substrate;
Superimposing the sealing substrate on the first surface so as to confine the metal in the hole;
The base substrate has a sealing region surrounding the opening and a bonding region surrounding the sealing region, and the base substrate and the sealing substrate are heated and bonded in the bonding region. A first joining step;
A gas cell manufacturing method comprising: a second bonding step of heat-bonding the base substrate and the sealing substrate in the sealing region and sealing the hole.   The gas cell manufacturing method according to claim 1, wherein the superimposing step includes a step of arranging the metal in the hole.   The gas cell manufacturing method according to claim 1, wherein the first bonding step performs bonding a plurality of times in the bonding region.   4. The method of manufacturing a gas cell according to claim 1, wherein the first bonding step performs continuous bonding from the bonding region toward the sealing region. 5.   4. The method according to claim 1, wherein the base substrate includes a plurality of the holes, and includes a step of separating each of the holes after the second bonding step. 5. Gas cell manufacturing method.   6. The gas cell manufacturing according to claim 1, wherein in the first bonding step, at least one of the base substrate and the sealing substrate is cooled and the heat bonding is performed. 6. Method.   The gas cell manufacturing according to any one of claims 1 to 6, wherein in the second bonding step, at least one of the base substrate and the sealing substrate is cooled and the heat bonding is performed. Method.   The method for producing a gas cell according to any one of claims 1 to 7, wherein an anodic bonding method is used for at least one of the first bonding step and the second bonding step.   The step of preparing includes a step of preparing the base substrate by bonding a substrate having a through-hole and a bottom substrate for closing one end of the through-hole. The manufacturing method of the gas cell as described in any one of Claims 8. A base substrate having a bottomed hole opening in the first surface, and having a metal inside the hole;
A gas cell comprising: a sealing substrate bonded to the first surface so as to close the hole. A gas cell containing metal atoms,
A light emitting portion for emitting light including resonance light to the gas cell;
A light detection unit for detecting light transmitted through the gas cell;
A control unit that controls the light emitting unit according to a signal from the light detection unit,
The gas cell has a bottomed hole opening in the first surface, and a base substrate provided with metal inside the hole;
An atomic oscillator comprising: a sealing substrate bonded to the first surface so as to close the hole.   An electronic apparatus comprising the atomic oscillator according to claim 11.   A moving body comprising the atomic oscillator according to claim 11.

Images