Inertial force sensor and method for manufacturing inertial force sensor

Abstract

To provide an inertial force sensor equipped with a sensor part air-tightly sealed in a highly evacuated package.SOLUTION: An inertial force sensor includes a package having an opening frame, a sensor part disposed inside the package, and a lid part covering the entire opening frame and joined to the opening frame. A closed space enclosed by the lid part is formed inside the package. The inertial force sensor includes a gas adsorption part disposed in the closed space. The gas adsorption part includes a plurality of pores therein.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present specification relates to an inertial force sensor and a method for manufacturing an inertial force sensor. [Background technology]

[0002] Inertial force sensors that are vacuum-tightly sealed in a package are known. The higher the degree of vacuum, the more likely it is that obstructive factors that attenuate the vibration energy of the inertial force sensor can be reduced, resulting in a more accurate gyro sensor. Related technology is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-129055 Summary of the Invention [Problem to be solved by the invention]

[0004] In some cases, outgassing may occur from components inside the package, or active gas may enter from the outside through the sealed portion of the package, making it difficult to achieve a high vacuum inside the package or to maintain that high vacuum state. [Means for solving the problem]

[0005] The inertial force sensor disclosed in this specification includes a package with an opening frame, a sensor unit disposed inside the package, and a lid that covers the entire opening frame and is joined to the opening frame. A closed space enclosed by the lid is formed inside the package. The inertial force sensor includes a gas adsorption unit disposed in the closed space. The gas adsorption unit has a plurality of pores therein.

[0006] According to the above structure, since the gas adsorption section has a plurality of pores inside, it is possible to increase the surface area per unit volume that can adsorb the active gas. As a result, the adsorption capacity of the active gas can be increased, and it is possible to continue adsorbing the outgassing from the components in the closed space and the active gas that has invaded the closed space for a long period of time. The high vacuum state inside the package can be maintained for a long period of time. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a top view of the gyro sensor 1. [Figure 2] FIG. 2 is a cross-sectional view of the gyro sensor 1. [Figure 3] FIG. 2 is an enlarged cross-sectional view of a gas adsorption section 60. [Figure 4] 3 is a flowchart showing an outline of a manufacturing process for the gyro sensor 1. [Figure 5] FIG. 1 is a cross-sectional view illustrating a step of supporting nanoparticles. [Figure 6] 1A to 1C are cross-sectional views illustrating a process of forming a sputtered film. [Figure 7] FIG. 2 is a schematic diagram of a sputtering device 70. [Figure 8A] FIG. 10 is an enlarged cross-sectional view of a gas adsorption section 60 in Example 2. [Figure 8B] FIG. 10 is an enlarged cross-sectional view of a gas adsorption section 60 in a first modified example of the second embodiment. [Figure 9] FIG. 10 is an enlarged cross-sectional view of a gas adsorption section 60 in Example 3. [Figure 10] FIG. 10 is an enlarged cross-sectional view of a gas adsorption section 60 in Example 4. [Figure 11] FIG. 10 is a cross-sectional view of the gyro sensor 1 of the fifth embodiment. [Figure 12] FIG. 10 is a cross-sectional view of the gyro sensor 1 of the sixth embodiment. [Figure 13] FIG. 1 is a perspective view showing a state before bonding of the Si wafers. [Figure 14] 2 is a diagram showing a cross-sectional structure of a sensor element 240. FIG. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0008] FIG. 1 shows a top view of a gyro sensor 1 according to this embodiment. For clarity, FIG. 1 shows a state in which a lid 130 has been removed. FIG. 2 shows a cross-sectional view taken along line II-II in FIG. 1. FIG. 2 is a cross-sectional view passing through a central axis CA. The gyro sensor 1 mainly comprises a sensor element 10, a package 100, and the lid 130. The sensor element 10 is vacuum-tightly sealed within the package 100.

[0009] (Configuration of sensor element 10) The sensor element 10 mainly comprises a base electrode 20, a glass oscillator 30, and paste 40. The base electrode 20 has a structure in which a silicon substrate 22 is laminated on a glass substrate 21.

[0010] The glass substrate 21 is made of a glass material that can be anodically bonded to the silicon substrate 22. An annular ring groove 21r is formed on the surface 21f of the glass substrate 21. A rim portion 30r of the glass vibrator 30 is inserted into the ring groove 21r.

[0011] The silicon substrate 22 includes a ring electrode 22c, multiple segmented electrodes 22d, and an outer peripheral electrode 22o. The ring electrode 22c is disposed on the surface 21f of the glass substrate 21. The ring electrode 22c has a cylindrical shape about a central axis CA and includes a through-hole 22h. The central axis CA passes through the center of the glass substrate 21 and is perpendicular to the surface 21f. The multiple segmented electrodes 22d are disposed rotationally symmetrically on a circle centered on the central axis CA. The multiple segmented electrodes 22d surround the ring electrode 22c. An electrode pad 23 is formed on each of the multiple segmented electrodes 22d. An annular ring-shaped through-hole 22r is formed between the outer periphery of the ring electrode 22c and the inner periphery of the multiple segmented electrodes 22d. A rim portion 30r of the glass vibrator 30 is inserted into the ring-shaped through-hole 22r. The outer peripheral electrode 22o surrounds the periphery of the segmented electrode 22d. The peripheral electrode 22o is connected to the annular electrode 22c by four wires 25. In this embodiment, the wires 25 are made of an Al film. BR pads 24 are disposed at the four corners of the peripheral electrode 22o.

[0012] The glass vibrator 30 includes a pillar portion 30p and a peripheral portion 30c. The pillar portion 30p is a tubular portion having a central axis CA. The peripheral portion 30c is a hollow, approximately hemispherical portion centered on the central axis CA. The cross-sectional shape of the glass vibrator 30 in a plane passing through the central axis CA is approximately M-shaped. The material of the glass vibrator 30 is fused silica (quartz).

[0013] A conductive film (not shown) is formed on the surface of the glass vibrator 30. Various materials can be used for the conductive film. In this example, the conductive film was a TiN film.

[0014] The glass vibrator 30 is fixed to the annular electrode 22c so that the central axis CA of the column portion 30p coincides with the central axis CA of the annular electrode 22c. Specifically, the bottom of the column portion 30p is adhered to the annular electrode 22c by paste 40. The paste 40 is a so-called conductive paste. The material form of the paste 40 is the same as that of the die bond material 50 described below. The paste 40 electrically connects the conductive film on the surface of the glass vibrator 30 to the annular electrode 22c. The annular electrode 22c is connected to the BR pad 24 via the wiring 25 and the peripheral electrode 22o. Therefore, the conductive film on the surface of the glass vibrator 30 and the BR pad 24 are electrically connected.

[0015] A die bond material 50 is disposed between the rear surface 21b of the glass substrate 21 and the mounting surface 101 of the package 100. The die bond material 50 is a conductive material used to bond and fix the glass substrate 21 to the mounting surface 101. Various materials can be used for the die bond material 50. For example, it may be a paste material (Ag paste) in which Ag particles are mixed into an organic binder material.

[0016] (Configuration of package 100 and lid 130) The configuration of the package 100 will be described with reference to Figures 1 and 2. A metal mounting surface 101 is disposed on the bottom surface inside the package 100. The multiple electrodes 102 are arranged to surround the mounting surface 101. The multiple electrode pads 23 of the sensor element 10 are connected to the corresponding electrodes 102 by wires 110. In this embodiment, the wires 110 are Au wires. As shown in FIG. 2, multiple pads 102p are arranged outside the package 100. The multiple pads 102p correspond to the multiple electrodes 102 and are connected to the multiple electrodes 102, respectively. The gyro sensor 1 can be connected to an external control circuit (not shown) via the multiple pads 102p.

[0017] A rectangular frame 103 is disposed around the outer periphery of the multiple electrodes 102. The frame 103 may be made of any insulating material (e.g., ceramic). A seal portion 120 is disposed on the upper surface of the frame 103. The seal portion 120 includes a lower electrode frame 121, a seal ring 122, and an upper electrode frame 123. The lower electrode frame 121 is disposed on the upper surface of the frame 103. The upper electrode frame 123 is disposed on the lower surface 130u of the lid 130. The lower electrode frame 121, the seal ring 122, and the upper electrode frame 123 are all rectangular and are formed at corresponding positions. The materials and thicknesses of the lower electrode frame 121, the seal ring 122, and the upper electrode frame 123 may vary. In this embodiment, the lower electrode frame 121 is made of an Au / Ni film, and the upper electrode frame 123 is made of an Au / Cr film. The seal ring 122 is made of AuSn with a thickness of about 100 μm.

[0018] The lid 130 is joined to the frame 103 by the seal portion 120. This forms an internal space IS surrounded by the inside of the package 100, the lid 130, and the seal portion 120. The sensor element 10 is housed in the internal space IS.

[0019] The lid 130 may be made of various materials. For example, a material called borosilicate glass may be used. Alternatively, a metal material based on nickel or Kovar may be used. The thickness of the lid 130 may be adjusted as needed.

[0020] As shown in FIG. 2, the lid 130 has a flat plate shape. The lid 130 covers the entire opening frame 103a. A gas adsorption unit 60 is disposed in an area of ​​the lower surface 130u of the lid 130 that is surrounded by the upper electrode frame 123. That is, the gas adsorption unit 60 is disposed on the upper wall surface that closes the internal space IS. The gas adsorption unit 60 is exposed to the internal space IS. The configuration of the gas adsorption unit 60 will be described later.

[0021] (Gyro sensor 1 operation) A capacitor is formed between each of the multiple split electrodes 22d and the glass vibrator 30. An electrical signal is applied to the multiple split electrodes 22d from an external control circuit (not shown) via the multiple pads 102p. By generating an electrostatic attraction between the glass vibrator 30 and the multiple split electrodes 22d, the glass vibrator 30 is excited in wine-glass mode at the resonant frequency. When an angular velocity ωz is applied around the z-axis in this state, a Coriolis force is generated. An amplitude corresponding to the generated Coriolis force is then generated in the detection direction. The generated amplitude can be detected by a change in capacitance of a capacitor formed between the split electrode 22d and the glass vibrator 30. As described above, gyro sensor 1, which is an inertial force sensor, functions.

[0022] (Configuration of gas adsorption section 60) 3 shows an enlarged cross-sectional view of the gas adsorption unit 60. The gas adsorption unit 60 includes a contact surface 60c, an outer surface 60s, a bulk region 60b, a plurality of first-type pores H1, and a plurality of second-type pores H2. The contact surface 60c is in contact with the lower surface 130u, which is a wall surface within the internal space IS. The outer surface 60s is the surface exposed within the internal space IS. The bulk region 60b is the region between the contact surface 60c and the outer surface 60s.

[0023] The gas adsorption section 60 is made of a getter material. The getter material is a material that adsorbs active gases other than rare gases (e.g., H, CH, H, O, N, CO, O, CO, hydrocarbons, etc.). In this embodiment, the getter material is an alloy made of one or more of zirconium (Zr), vanadium (V), titanium (Ti), niobium (Nb), tantalum (Ta), and hafnium (Hf).

[0024] A plurality of first-type pores H1 and second-type pores H2 are formed inside the gas adsorption unit 60. Each of the plurality of first-type pores H1 has a substantially spherical hollow structure corresponding to a spherical nanoparticle. Each of the plurality of second-type pores H2 has a hollow structure corresponding to a sacrificial particle. The shape of the second-type pores H2 is not limited to a spherical shape and can be various shapes. Note that nanoparticles and sacrificial particles will be described later.

[0025] The average pore volume V2 of the second-type pores H2 is smaller than the average pore volume V1 of the first-type pores H1. Preferably, the average pore volume V2 is equal to or smaller than a fraction of the average pore volume V1.

[0026] Some of the first-type pores H1 are stacked in the film thickness direction (z direction) and merged with one another (see region R1). The stacked and merged first-type pores H1 have a larger volume than individual, non-stacked first-type pores H1.

[0027] Some of the second-type pores H2 are connected to each other and unite to form connecting pores H2c. Some of the connecting pores H2c connect the outer surface 60s of the gas adsorbing section 60 to the first-type pores H1. That is, the connecting pores H2c include some that do not connect the outer surface 60s to the first-type pores H1.

[0028] A sacrificial material 64 is present inside at least one of the multiple first-type voids H1 and multiple second-type voids H2. The sacrificial material 64 is the remaining portion of the nanoparticles 61 and sacrificial particles 63 described below. In FIG. 3, the sacrificial material 64 inside the first-type voids H1 and the second-type voids H2 is indicated by black fill. In this embodiment, the sacrificial material 64 is silicon oxide. The amount of sacrificial material 64 is greater on the contact surface 60c side than on the outer surface 60s side. That is, in FIG. 3, the black fill area increases as you get closer to the contact surface 60c.

[0029] Here, the first peak P1 and the second peak P2 are defined. The first peak P1 is the peak position of the density of the plurality of first-type vacancies H1 in the depth direction (z direction). The second peak P2 is the peak position of the density of the plurality of second-type vacancies H2 in the depth direction. The density is the density of a point when a vacancy is considered to be a point with no volume. As shown in FIG. 3, the second peak P2 is located closer to the outer surface 60s (i.e., in the -z direction) than the first peak P1.

[0030] Grain boundaries GB exist throughout the bulk region 60b. In the drawings of this specification, the grain boundaries GB are schematically shown by a thin mesh. The grain boundaries GB are connected to a plurality of first-type vacancies H1 and a plurality of second-type vacancies H2. The first-type vacancies H1 are not exposed on the outer surface 60s.

[0031] (Manufacturing method of gyro sensor 1) FIG. 4 shows a flowchart outlining the manufacturing process of the gyro sensor 1. In step S10, a package 100 is prepared. In step S20, a sensor element 10 is prepared. In this specification, a Bird-bath Resonator Gyroscope (BRG) using a glass resonator made of fused silica is used as the sensor element 10. Note that a detailed description of the BRG will be omitted. In step S30, a lid 130 corresponding to the size of the opening frame 103a is prepared.

[0032] In step S40, the sensor element 10 is mounted and fixed on the mounting surface 101 of the package 100. Thereafter, the electrode pads 23 and BR pads 24 are electrically connected to the electrodes 102 of the package 100 by Au wires 110.

[0033] In step S50, a process of forming the gas adsorption section 60 is performed. The process of forming the gas adsorption section 60 includes a nanoparticle supporting process (S51), a sputtered film forming process (S52), and an etching process (S53). Each process will be described using the cross-sectional views of FIGS. 5 and 6.

[0034] In step S51, a plurality of nanoparticles 61 are supported on the lower surface 130u, which serves as a carrier for the gas adsorption unit 60 (see FIG. 5). The nanoparticles 61 are spheres made of glass (e.g., silica, quartz glass). Surface modification of the lower surface 130u can be used as a supporting method. Conventional techniques can be applied to the supporting method, so a description thereof will be omitted here. Some of the nanoparticles 61 can be in contact with each other and stacked (see region R2).

[0035] In step S52, a sputtered film 62 is formed using a binary sputtering apparatus 70. The sputtered film 62 is formed to a thickness that covers the plurality of nanoparticles 61. FIG. 7 shows a schematic configuration diagram of the sputtering apparatus 70. A first material 81 is attached to a first target 71. A second material 82 is attached to a second target 72. The first material 81 is made of a getter material, and the second material 82 is made of a material that forms the sacrificial particles 63. Specifically, the first material 81 is made of zirconium (Zr), vanadium (V), titanium (Ti), niobium (Nb), tantalum (Ta), hafnium (Hf), or an alloy of any of these. The second material 82 is made of glass (e.g., silicon oxide, silica, quartz glass, etc.).

[0036] A dedicated tray 75 is placed on a substrate holder 74 in a vacuum chamber 73. A plurality of lids 130 are arranged on the tray 75, and a stencil mask 76 is placed above the lids 130. The stencil mask 76 allows the film formation area of ​​the lid 130 to be limited. Then, based on the principle of the sputtering method, the film is formed in Ar plasma (see FIG. 6). It is preferable to perform sputtering film formation while heating the substrate. This promotes crystallization of the sputtered film 62, making it possible to form grain boundaries GB.

[0037] In the film formation process, the proportions of getter material components and sacrificial particle components in the sputtered film 62 can be controlled by controlling the power applied to the first target 71 and the second target 72. In order to increase the proportion of sacrificial particles 63 in the sputtered film 62, the power of the second target 72 can be set higher relative to the power of the first target 71. After the sputtered film 62 has been formed to the desired thickness, the stencil mask 76 is removed.

[0038] In step S53, the nanoparticles 61 and sacrificial particles 63 are etched. Specifically, the lid 130 on which the sputtered film 62 is formed is placed in a vapor etching device. The etching gas (hydrofluoric acid vapor) penetrates into the interior of the sputtered film 62 through the grain boundaries GB (see FIG. 3). The glass nanoparticles 61 and sacrificial particles 63 are etched and removed, forming a hollow portion. The amount of etching can be controlled by managing the vapor etching time. Furthermore, the portions of the nanoparticles 61 and sacrificial particles 63 that are not removed remain as sacrificial material 64. This completes the gas adsorption section 60 shown in FIG. 3.

[0039] The nanoparticles 61 and the sacrificial particles 63 are vapor-etched via the grain boundaries GB. Therefore, the contact surface 60c side is less susceptible to etching than the outer surface 60s side. That is, the etching rate decreases as the depth from the outer surface 60s increases. Therefore, by appropriately setting the vapor etching time, it is possible to create a state in which the amount of sacrificial material 64 (silicon oxide) is greater on the outer surface 60s side than on the contact surface 60c side.

[0040] In step S60, a vacuum hermetic sealing process is performed. First, an upper electrode frame 123 having a rectangular frame shape is formed on the lid 130. The upper electrode frame 123 has a shape corresponding to the lower electrode frame 121 of the frame body 103. Next, the package 100 formed in step S40 is placed in a vacuum. A seal ring 122 having the same frame shape as the lower electrode frame 121 is placed on top of the lower electrode frame 121. The lid 130 is placed on top of the seal ring 122. At this time, the positions of the lower electrode frame 121, seal ring 122, and upper electrode frame 123 are adjusted so that they overlap with each other. After that, they are heated at 360°C to perform a gas removal process, and the sensor element 10 is vacuum hermetically sealed by eutectic bonding. At this time, a load may be applied to the lid 130 to press it, if necessary. Since the seal portion 120 provides hermetic sealing, the internal pressure of the package 100 can be maintained at a desired vacuum level.

[0041] In step S70, a heat treatment process is performed on the sealed state. This activates the getter material of the gas adsorption section 60, allowing it to adsorb gas remaining in the internal space IS. As a result, the sensor element 10 is hermetically sealed in the internal space IS at a higher degree of vacuum. The heat treatment as the activation process in step S70 may be used in combination with or may be substituted for the heat treatment during bonding in step S60. Through the above processes, the gyro sensor 1 is completed.

[0042] (effect) Outgassing may occur from components inside the package 100 (e.g., the die bond material 50), or active gas may infiltrate the internal space IS from the outside through the seal portion 120 of the package 100. In such cases, it becomes difficult to achieve a high vacuum inside the package 100 or maintain the high vacuum state. Therefore, the technology of this specification provides a gas adsorption section 60 disposed in the internal space IS. The gas adsorption section 60 contains a plurality of first-type pores H1 and second-type pores H2, thereby increasing the surface area per unit volume that can adsorb active gas. As a result, the active gas adsorption capacity of the gas adsorption section 60 can be increased, allowing it to continue adsorbing outgassing from components and active gas that has infiltrated the internal space IS for a long period of time. The high vacuum state inside the package 100 can be maintained for a long period of time.

[0043] In the gas adsorption section 60 of this specification, the connecting holes H2c can connect the outer surface 60s exposed to the internal space IS with the first-type pores H1. This allows the active gas in the internal space IS to be guided to the first-type pores H1 through the connecting holes H2c. Compared to the case where the active gas is guided to the first-type pores H1 through the grain boundaries GB, this allows the active gas to pass through more easily, thereby improving the adsorption efficiency.

[0044] In the gas adsorption section 60 of this specification, the second peak P2 is positioned closer to the outer surface 60s than the first peak P1 (see FIG. 3). That is, the density of the second-type pores H2 is higher on the outer surface 60s side. This makes it easier to realize the above-described configuration in which the outer surface 60s and the first-type pores H1 are connected by the connecting pores H2c.

[0045] In the gas adsorption unit 60 of this specification, the amount of sacrificial material 64 (silicon oxide) is greater on the contact surface 60c side than on the outer surface 60s side (see FIG. 3). This reduces the porosity on the contact surface 60c side, increasing the film strength, thereby improving the adhesion between the gas adsorption unit 60 and the wall surface (lower surface 130u). Furthermore, because the porosity can be made higher on the outer surface 60s side than on the contact surface 60c side, the surface area on the outer surface 60s side can be increased. This makes it possible to improve adsorption efficiency.

[0046] (First Modification of the First Embodiment) The shape of the nanoparticles 61 is not limited to a sphere but can be various shapes. Furthermore, the shape of the first-type voids H1 can also be various shapes according to the shape of the nanoparticles 61. For example, the nanoparticles 61 may be rod-shaped. The cross section perpendicular to the longitudinal axis of the rod is not limited to a circle but may be rectangular.

[0047] (Second Modification of the First Embodiment) The order of the flowchart in Fig. 4 is an example, and the order may be changed as appropriate depending on the ease of manufacturing. [Example]

[0048] In Example 2, an embodiment in which the structure of the gas adsorption unit 60 is different from that of Example 1 will be described. Portions common to Examples 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 8A shows an enlarged cross-sectional view of the gas adsorption unit 60 in Example 2. FIG. 8A is a view of the same location as FIG. 3 in Example 1. As shown in FIG. 8A, the gas adsorption unit 60 in Example 2 has only a plurality of first-type pores H1, and does not have a plurality of second-type pores H2.

[0049] A method for manufacturing the gas adsorption section 60 of Example 2 will be described. Only the different parts of the flowchart (FIG. 4) from Example 1 will be described. In step S52, sputtering film formation is performed using only the first target 71. As a result, the sputtered film 62 is composed only of the getter material, and the sacrificial particles 63 are no longer contained in the sputtered film 62. Thereafter, in step S53, the nanoparticles 61 are etched. As a result, the gas adsorption section 60 of Example 2 shown in FIG. 8A is completed.

[0050] According to the configuration of the second embodiment, it is possible to increase the surface area per unit volume of the gas adsorption portion 60, similarly to the first embodiment. It is possible to maintain a high vacuum state inside the package 100 for a long period of time.

[0051] (First Modification of the Second Embodiment) A portion of the surface of the gas adsorption section 60 shown in FIG. 8A may be removed by ion milling using Ar gas or CMP (Chemical Mechanical Polishing). This allows a new outer surface 60sN to be formed as shown in FIG. 8B. Furthermore, openings of the first-type vacancies H1 can be formed on the new outer surface 60sN. This allows the active gas to pass more easily than when the active gas is guided to the first-type vacancies H1 via the grain boundaries GB, thereby improving the adsorption efficiency. Furthermore, by improving the porosity of the gas adsorption section 60, the surface area of ​​the gas adsorption surface can be expanded. [Example]

[0052] In Example 3, an embodiment in which the structure of the gas adsorption section 60 is different from that of Example 1 will be described. Portions common to Examples 1 and 3 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 9 shows an enlarged cross-sectional view of the gas adsorption section 60 in Example 3. FIG. 9 is a view of the same location as FIG. 3 in Example 1. As shown in FIG. 9, the gas adsorption section 60 in Example 3 only has a plurality of second-type pores H2, and does not have a plurality of first-type pores H1.

[0053] In the gas adsorption portion 60 of Example 3, the density of the second-type pores H2 increases toward the outer surface 60s. In other words, the porosity in the bulk region 60b is higher on the outer surface 60s side than on the contact surface 60c side.

[0054] A method for manufacturing a gas adsorption section 60 of Example 3 will be described. Only the different parts of the flowchart of Example 1 (FIG. 4) will be described. The nanoparticle supporting process of step S51 is omitted. In step S52, sputtering film formation is performed using both the first target 71 and the second target 72. Then, as the thickness of the sputtered film 62 increases, the power of the second target 72 relative to the power of the first target 71 is changed so as to increase. This allows the proportion of sacrificial particle components in the sputtered film 62 to increase toward the outer surface 60s. Thereafter, in step S53, the nanoparticles 61 are etched. This completes the gas adsorption section 60 of Example 3 shown in FIG. 9.

[0055] (effect) In the gas adsorption unit 60 of Example 3, the contact surface 60c side can be made denser than the outer surface 60s side. By reducing the porosity on the contact surface 60c side and increasing the film strength, the adhesion between the gas adsorption unit 60 and the wall surface (lower surface 130u) can be improved. In addition, the porosity on the outer surface 60s side can be increased to increase the surface area, thereby improving the adsorption efficiency. [Example]

[0056] In Example 4, an embodiment in which the structure of the gas adsorption unit 60 is different from that of Example 1 will be described. Portions common to Examples 1 and 4 are designated by the same reference numerals, and description thereof will be omitted. Fig. 10 shows an enlarged cross-sectional view of the gas adsorption unit 60 in Example 4. Fig. 10 is a view of the same location as Fig. 3 of Example 1.

[0057] The gas adsorption unit 60 includes a first layer L1 and a second layer L2. The first layer L1 is a layer that mainly contains first-type vacancies H1. The second layer L2 is a layer that mainly contains second-type vacancies H2. That is, the first layer L1 is a layer in which the density of the first-type vacancies H1 is higher than the density of the second-type vacancies H2. The second layer L2 is a layer in which the density of the second-type vacancies H2 is higher than the density of the first-type vacancies H1. The first layer L1 is disposed on the surface of the lower surface 130u. The second layer L2 is laminated on the surface of the first layer L1. That is, the second layer L2 is located closer to the outer surface 60s of the gas adsorption unit 60 than the first layer L1.

[0058] A method for manufacturing a gas adsorption section 60 according to Example 4 will be described. Only the differences from the flowchart of Example 1 (FIG. 4) will be described. In step S52, first, a first layer L1 is formed. By forming the layer using only the first target 71, the first layer L1 can be composed of only a getter material. Subsequently, a second layer L2 is formed. By forming the layer using both the first target 71 and the second target 72, the second layer L2 can be composed of both a getter material and sacrificial particles. Thereafter, in step S53, the sacrificial particles are removed by etching.

[0059] (effect) In the gas adsorption section 60 of Example 4, the surface area of ​​the first layer L1 can be increased by the first-type pores H1, and the film strength can be increased by forming the first layer L1 only from a getter material. Furthermore, by including a plurality of second-type pores H2 in the second layer L2, the outer surface 60s and the first-type pores H1 can be connected by the connecting holes H2c. This makes it possible to achieve both improved adhesion and improved adsorption efficiency of the gas adsorption section 60. [Example]

[0060] Fig. 11 shows a cross-sectional view of the gyro sensor 1 of Example 5. Fig. 11 is a drawing corresponding to Fig. 2 of Example 1. Components common to Examples 1 and 5 are denoted by the same reference numerals, and description thereof will be omitted.

[0061] A specific wall surface SW is formed on the lower surface 130u of the lid 130 of Example 5. That is, the specific wall surface SW is arranged within the internal space IS. The specific wall surface SW is a surface on which a minute uneven structure is formed. The gas adsorption section 60 of Example 5 is arranged along the unevenness of the specific wall surface SW. This allows the gas adsorption section 60 of Example 5 to have a larger surface area than the gas adsorption section 60 of Example 1 (see FIG. 2), which is arranged on the lower surface 130u without unevenness. This makes it possible to improve adsorption efficiency. [Example]

[0062] Fig. 12 shows a cross-sectional view of the gyro sensor 1 of Example 6. Fig. 12 is a diagram corresponding to Fig. 2 of Example 1. Components common to Examples 1 and 6 are denoted by the same reference numerals, and description thereof will be omitted.

[0063] In Example 6, a gas adsorption section 60 is disposed in the sensor element 10. Specifically, a recessed section 21c is formed on the rear surface 21b of the glass substrate 21. The gas adsorption section 60 is disposed inside the recessed section 21c. This embodiment also enables the gas adsorption section 60 to adsorb outgassing from the die bond material 50 and active gases that have entered the internal space IS.

[0064] 12, the gas adsorption unit 60 may be disposed in various positions. For example, the gas adsorption unit 60 may be disposed on the side surface of the glass substrate 21 or on the inner wall of the frame 103. [Example]

[0065] In Example 7, a WLP (Wafer Level Packaging) structure using Si wafer bonding technology will be described. Fig. 13 shows the state before the Si wafer is bonded. The WLP structure 201 includes a package base 210 and a lid 230.

[0066] The package base 210 includes a Si substrate 211, an oxide film layer 212, and a Si element substrate 213. The Si element substrate 213 and the Si substrate 211 are bonded via the oxide film layer 212. In other words, the package base 210 is an SOI (Silicon On Insulator) wafer. A plurality of sensor elements 240 are formed on the Si element substrate 213. The structure of the sensor elements 240 will be described later.

[0067] FIG. 14 shows the cross-sectional structure of a representative sensor element 240. The sensor element 240 mainly comprises an oscillator 241 and an electrode portion 242. The oscillator 241 and the electrode portion 242 are formed on a Si element substrate 213 by deep etching of Si. The oscillator 241 and the electrode portion 242 have a structure that is generally used in MEMS (Micro Electro Mechanical Systems) sensors. Therefore, a detailed description will be omitted. The sensor element 240 can detect angular velocity by reading the change in capacitance that occurs between the oscillator 241 and the electrode portion 242 with a comb-tooth structure.

[0068] The lid portion 230 is made of a single single-crystal Si substrate. A recess 230d is formed on the lower surface 230u of the lid portion 230 by deep etching of Si. This forms a bonding ring 230r on the lid portion 230. The bonding ring 230r is an integral part of the lid portion 230 and is made of Si. A bonding layer 220 made of a silicon oxide film is disposed on the surface of the bonding ring 230r.

[0069] A bonding ring 213r is formed on the Si element substrate 213. The bonding ring 213r is made of Si and is an integral part of the package base 210. The bonding ring 213r of the Si element substrate 213 has the same shape as the bonding ring 230r of the lid portion 230.

[0070] A gas adsorption unit 260 is exposed on the upper wall surface (the lower surface of the lid portion 230) that closes the internal space IS. The gas adsorption unit 260 is similar to the gas adsorption unit 60 described in Examples 1-4. Note that, since semiconductor manufacturing technology is used in Example 7, it is preferable in terms of the manufacturing process to apply the structure of the gas adsorption unit 60 of Example 3 to the gas adsorption unit 260.

[0071] When fabricating the WLP structure 201 of Example 7, the gas adsorption portion 260 can be formed at the wafer level. That is, a stencil mask is placed on the desired cap wafer, and the gas adsorption portion 260 is formed by sputtering. This method allows the gas adsorption portion 260 to be selectively formed only on the desired portion of the cap wafer.

[0072] (effect) In the sensor element 240 of Example 7, the gas in the internal space IS can be adsorbed by the gas adsorption section 260. This makes it possible to maintain the internal space IS in a high vacuum state for a long period of time. Furthermore, since the sensor element 240 can be manufactured using MEMS technology, it can be made smaller in size than the sensors of Examples 1-6, which do not use MEMS technology.

[0073] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives itself has technical utility.

[0074] (Variation) The material of the nanoparticles 61 and the sacrificial particles 63 is not limited to glass (silicon oxide), and various materials can be used. In this case, in step S53, the silicon particles can be etched away by vapor-phase etching using xenon difluoride (XeF2, xenon difluoride).

[0075] Aspects of the present technology are listed below. [Aspect 1] a package having an opening frame; a sensor unit disposed inside the package; a lid portion that covers the entire opening frame and is joined to the opening frame; An inertial force sensor comprising: A closed space is formed inside the package by the lid, the inertial force sensor includes a gas adsorption unit disposed in the closed space, The gas adsorption portion has a plurality of pores therein. Inertial force sensor. [Aspect 2] the gas adsorption unit includes a contact surface in contact with a wall surface within the closed space, an outer surface exposed within the closed space, and a bulk region between the contact surface and the outer surface; 2. The inertial force sensor according to aspect 1, wherein the porosity of the pores in the bulk region is higher on the outer surface side than on the contact surface side. [Aspect 3] the plurality of pores include a plurality of first-type pores and a plurality of second-type pores, an average pore volume of the plurality of second-type pores is smaller than an average pore volume of the plurality of first-type pores; 3. The inertial force sensor according to aspect 1 or 2, wherein a depth direction peak of the density of the second-type vacancies is located closer to the outer surface of the gas adsorption portion than a depth direction peak of the density of the first-type vacancies. [Aspect 4] the plurality of pores include connected pores formed by connecting the plurality of second-type pores to each other, 4. The inertial force sensor according to aspect 3, wherein the connecting hole connects an outer surface of the gas adsorbing portion exposed in the closed space to the first-type pores. [Aspect 5] the plurality of pores include a plurality of first-type pores and a plurality of second-type pores, an average pore volume of the plurality of second-type pores is smaller than an average pore volume of the plurality of first-type pores; The gas adsorption section is a first layer in which the density of the first-type vacancies is higher than the density of the second-type vacancies; a second layer in which the density of the second-type vacancies is higher than the density of the first-type vacancies; It is equipped with 3. The inertial force sensor according to aspect 1 or 2, wherein the second layer is located closer to the outer surface of the gas adsorbing portion than the first layer. [Aspect 6] the plurality of pores include connected pores formed by connecting the plurality of second-type pores to each other, 6. The inertial force sensor according to aspect 5, wherein the connecting hole connects the outer surface of the gas adsorbing portion and the first-type pores. [Aspect 7] the gas adsorption unit has a contact surface in contact with a wall surface within the closed space and an outer surface exposed within the closed space, the gas adsorption portion is made of an alloy, silicon oxide or silicon is present inside at least one of the plurality of pores, The inertial force sensor according to any one of aspects 1 to 6, wherein the amount of silicon oxide or silicon present is greater on the contact surface side than on the outer surface side. [Aspect 8] A specific wall surface having projections and recesses is arranged in the closed space, The inertial force sensor according to any one of aspects 1 to 7, wherein the gas adsorption portion is disposed along the irregularities of the specific wall surface. [Aspect 9] The inertial force sensor according to any one of aspects 1 to 8, wherein the gas adsorption unit is disposed in the lid unit that forms part of the closed space, or in the sensor unit. [Aspect 10] a package having an opening frame; a sensor unit disposed inside the package; a lid portion that covers the entire opening frame and is joined to the opening frame; A method for manufacturing an inertial force sensor comprising: A closed space is formed inside the package by the lid, the inertial force sensor includes a gas adsorption unit disposed in the closed space, the gas adsorption portion has a plurality of pores therein, fixing the sensor unit inside the package; forming a sputtered film containing at least one of nanoparticles and sacrificial particles; removing the nanoparticles and the sacrificial particles in the sputtered film by etching; a step of joining the opening frame and the lid portion in a vacuum atmosphere; performing a heat treatment; A method for manufacturing an inertial force sensor, comprising: [Explanation of symbols]

[0076] 1: Gyro sensor 10: Sensor element 60: Gas adsorption portion 60c: Contact surface 60b: Bulk region 60s: Outer surface 100: Package 103a: Opening frame 121: Lower electrode frame 123: Upper electrode frame 130: Lid H1: First type hole H2: Second type hole IS: Internal space

Claims

1. a package having an opening frame; a sensor unit disposed inside the package; a lid portion that covers the entire opening frame and is joined to the opening frame; An inertial force sensor comprising: A closed space is formed inside the package by the lid, the inertial force sensor includes a gas adsorption unit disposed in the closed space, The gas adsorption portion has a plurality of pores therein. Inertial force sensor.

2. the gas adsorption unit includes a contact surface in contact with a wall surface within the closed space, an outer surface exposed within the closed space, and a bulk region between the contact surface and the outer surface; 2. The inertial force sensor according to claim 1, wherein a porosity of the pores in the bulk region is higher on the outer surface side than on the contact surface side.

3. the plurality of pores include a plurality of first-type pores and a plurality of second-type pores, an average pore volume of the plurality of second-type pores is smaller than an average pore volume of the plurality of first-type pores; 2. The inertial force sensor according to claim 1, wherein a depth direction peak of the density of the second-type vacancies is located closer to the outer surface of the gas adsorption portion than a depth direction peak of the density of the first-type vacancies.

4. the plurality of pores include connecting pores formed by connecting the plurality of second-type pores to each other, 4. The inertial force sensor according to claim 3, wherein the connecting hole connects an outer surface of the gas adsorption portion exposed in the closed space to the first-type pores.

5. the plurality of pores include a plurality of first-type pores and a plurality of second-type pores, an average pore volume of the plurality of second-type pores is smaller than an average pore volume of the plurality of first-type pores; The gas adsorption section is a first layer in which the density of the first-type vacancies is higher than the density of the second-type vacancies; a second layer in which the density of the second-type vacancies is higher than the density of the first-type vacancies; It is equipped with 2. The inertial force sensor according to claim 1, wherein the second layer is located closer to the outer surface of the gas adsorption portion than the first layer.

6. the plurality of pores include connecting pores formed by connecting the plurality of second-type pores to each other, The inertial force sensor according to claim 5 , wherein the connecting hole connects an outer surface of the gas adsorption portion and the first-type pores.

7. the gas adsorption unit has a contact surface in contact with a wall surface within the closed space and an outer surface exposed within the closed space, the gas adsorption portion is made of an alloy, silicon oxide or silicon is present inside at least one of the plurality of pores, 2. The inertial force sensor according to claim 1, wherein the amount of silicon oxide or silicon present is greater on the contact surface side than on the outer surface side.

8. A specific wall surface having projections and recesses is arranged in the closed space, The inertial force sensor according to claim 1 , wherein the gas adsorption portion is disposed along the irregularities of the particular wall surface.

9. 2. The inertial force sensor according to claim 1, wherein the gas adsorption portion is disposed in the lid portion that forms a part of the closed space, or in the sensor portion.

10. a package having an opening frame; a sensor unit disposed inside the package; a lid portion that covers the entire opening frame and is joined to the opening frame; A method for manufacturing an inertial force sensor comprising: A closed space is formed inside the package by the lid, the inertial force sensor includes a gas adsorption unit disposed in the closed space, the gas adsorption portion has a plurality of pores therein, fixing the sensor unit inside the package; forming a sputtered film containing at least one of nanoparticles and sacrificial particles; removing the nanoparticles and the sacrificial particles in the sputtered film by etching; a step of joining the opening frame and the lid portion in a vacuum atmosphere; performing a heat treatment; A method for manufacturing an inertial force sensor, comprising:

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