JP7578166B2 - Capacitive MEMS sensor, electronic device and mobile object - Google Patents

Description

The present invention relates to electronic devices, methods for manufacturing electronic devices, electronic equipment, and mobile objects.

Conventionally, for example, as electronic devices equipped with functional elements that detect physical quantities using silicon MEMS (Micro Electro Mechanical Systems) technology, there are known acceleration sensors and gyro sensors in which functional elements formed from a silicon substrate or the like are provided on a package substrate (base) such as a semiconductor substrate or glass substrate, and the functional elements are hermetically sealed with a sealing material.

For example, Patent Document 1 discloses a method for manufacturing such an electronic device by heating low-melting-point glass as a sealing material above its flow point in a reduced pressure atmosphere and bonding the base substrate and lid together to produce a package. The low-melting-point glass described in Patent Document 1 contains a gap material, and a method for manufacturing an electronic device is disclosed in which the gap material is used to keep the gap between the base substrate and the lid constant, ensuring the presence of the low-melting-point glass to bond them together.

JP 2014-38969 A

However, in the method of manufacturing an electronic device described in Patent Document 1, by adding a gap material that does not have a bonding function to the low-melting glass, the content of components with a bonding function contained in the low-melting glass is reduced, and there is a risk of the bonding strength between the base substrate and the lid being reduced.

The present invention has been made to solve at least some of the above problems, and can be realized in the following forms or application examples.

[Application Example 1] The electronic device according to this application example includes a base, a functional element bonded onto the base, and a lid that is bonded to a joint on the base via a bonding material and covers the functional element to form an internal space between the base and the lid, and includes a gap member that is in contact with the surface of the base facing the lid and the surface of the lid facing the base, and the height of the gap member is greater than the thickness of the bonding material.

With this configuration, when the base and the lid are joined via the bonding material, the distance between the base and the lid is determined by the height of the gap member. As a result, regardless of the amount of bonding material applied to the joint, the bonding material can be reliably inserted at a constant height (amount) between the base and the lid.

Therefore, even if the amount of bonding material applied to the joint is greater than the specified amount, it is possible to prevent the gap between the base and the lid from becoming larger. Also, even if the amount of bonding material applied to the joint is less than the specified amount, it is possible to prevent the gap between the base and the lid from becoming smaller. As a result, the gap between the base and the lid can be kept constant and the joint can be reliably bonded, thereby reducing deterioration in the bonding strength and providing a highly reliable electronic device.

[Application Example 2] In the electronic device according to the above application example, the height of the gap member is approximately the same as the thickness of the functional element.

This configuration allows the gap member and the functional element to be easily formed together from the same substrate, reducing costs.

[Application Example 3] The electronic device according to the above application example is characterized in that the gap member is made of the same material as the functional element.

With this configuration, a manufacturing process just for forming the gap member is not required, so the gap member can be obtained without increasing costs.

[Application Example 4] The electronic device according to the above application example is characterized in that the gap member is arranged to surround the functional element.

According to this configuration, when the base and the lid are joined via the bonding material, the distance between the base and the lid is determined by the height of the gap member around the periphery of the functional element. As a result, regardless of the amount of bonding material applied to the joint, the bonding material can be reliably inserted at a constant height (amount) between the base and the lid around the periphery of the functional element. As a result, the base and the lid can be reliably joined.

[Application Example 5] In the electronic device according to the above application example, the gap member is characterized by being formed containing silicon.

This configuration makes it possible to apply processing techniques used in the manufacture of silicon semiconductor devices when forming the gap member. As a result, the gap member can be formed finely and with high precision.

[Application Example 6] In the electronic device according to the above application example, the lid is characterized in that it is formed to contain silicon.

This configuration makes it possible to apply processing techniques used in the manufacture of silicon semiconductor devices when forming the lid. As a result, the lid can be formed finely and with high precision.

[Application Example 7] In the electronic device according to the above application example, the gap member is integrated with the lid.

This configuration allows the gap member and the lid to be easily formed from the same substrate at the same time, reducing costs.

[Application Example 8] In the electronic device according to the above application example, the substrate is characterized in that it is formed to contain glass.

With this configuration, when maintaining insulation between the substrate and the functional element, there is no need to interpose an insulating film on the substrate, and insulation separation can be easily achieved.

[Application Example 9] The electronic device according to the above application example is characterized in that the bonding material is formed to contain low-melting point glass.

With this configuration, the base and the lid can be joined at a lower temperature than when they are joined using resin, metal, soda glass, etc. As a result, the base and the lid are less exposed to high temperatures, and damage to them can be suppressed.

[Application Example 10] The method for manufacturing an electronic device according to this application example includes a first bonding step of bonding a functional element onto a base, an etching step of forming a gap member, and a second bonding step of bonding a lid to a joint of the base via a flexible bonding material so as to cover the functional element and form an internal space between the functional element and the base, the second bonding step including a step of abutting the gap member against a surface of the base facing the lid and a surface of the lid facing the base, and the height of the gap member is greater than the thickness of the bonding material.

According to this method, when the base and the lid are joined via the bonding material, the distance between the base and the lid is determined by the height of the gap member. As a result, the bonding material can be reliably inserted at a constant height between the base and the lid, regardless of the amount of bonding material applied to the joint.

Therefore, even if the amount of bonding material applied to the joint is greater than the specified amount, the gap between the base and the lid can be prevented from becoming larger. Also, even if the amount of bonding material applied to the joint is less than the specified amount, the gap between the base and the lid can be prevented from becoming smaller. As a result, the base and the lid can be reliably bonded, reducing the deterioration of the bonding strength and providing a method for manufacturing a highly reliable electronic device.

[Application Example 11] The electronic device according to this application example is characterized by including the electronic device described above.

With such electronic equipment, the electronic device described above is installed, making it possible to obtain highly reliable electronic equipment.

[Application Example 12] The moving object according to this application example is characterized by being equipped with the electronic device described above.

With such a mobile body, the above-mentioned electronic device is installed, making it possible to obtain a highly reliable mobile body.

FIG. 1 is a plan view illustrating a schematic configuration of an acceleration sensor as an example of an electronic device. FIG. 2 is a front cross-sectional view taken along line AA in FIG. 1, illustrating a schematic configuration of the acceleration sensor. FIG. 3 is an enlarged front cross-sectional view of a gap member and a protrusion portion of FIG. 2 . 4 is a flowchart showing an outline of a manufacturing method for the acceleration sensor according to the embodiment. 1A to 1C are front cross-sectional views showing a process flow 1 of a method for manufacturing an acceleration sensor. 4A to 4C are front cross-sectional views showing process flows 2 and 4 of the manufacturing method of the acceleration sensor. 5A to 5C are front cross-sectional views showing a process flow 3 of the manufacturing method of the acceleration sensor. 5A to 5C are front cross-sectional views showing a process flow 5 of the manufacturing method of the acceleration sensor. 6A to 6C are front cross-sectional views showing a process flow 6 of the manufacturing method of the acceleration sensor. 7A to 7C are front cross-sectional views showing a process flow 7 of the manufacturing method of the acceleration sensor. FIG. 11 is an enlarged front cross-sectional view of the acceleration sensor according to the first modification example, showing a gap member and a protrusion. FIG. 11 is a schematic plan view showing an arrangement of gap members according to Modification 2. FIG. 11 is a schematic plan view showing an arrangement of gap members according to Modification 3. FIG. 13 is a schematic plan view showing an arrangement of gap members according to Modification 4. FIG. 13 is a schematic plan view showing an arrangement of gap members according to Modification 5. FIG. 13 is a schematic plan view showing an arrangement of gap members according to Modification 6. FIG. 1 is a perspective view showing a schematic configuration of a mobile (or notebook) personal computer as an example of an electronic device provided with the electronic device. FIG. 1 is a perspective view showing a schematic configuration of a mobile phone (including a PHS) as an example of an electronic device provided with the electronic device. FIG. 1 is a perspective view showing a schematic configuration of a digital still camera as an example of an electronic device. FIG. 1 is a perspective view illustrating a vehicle as an example of a moving object equipped with an electronic device.

The present embodiment will be described below. Note that the present embodiment described below does not unduly limit the contents of the present invention described in the claims. Furthermore, not all of the configurations described in the present embodiment are necessarily essential components of the present invention. Furthermore, for the sake of convenience in the following description, the X-axis, Y-axis, and Z-axis are illustrated in each figure as three mutually orthogonal axes, and the direction parallel to the X-axis is referred to as the "X-axis direction," the direction parallel to the Y-axis is referred to as the "Y-axis direction," and the direction parallel to the Z-axis is referred to as the "Z-axis direction." Additionally, the +Z-axis direction side is referred to as the "upper" and the -Z-axis direction side is referred to as the "lower."

<Embodiment>
[Accelerometer]
The structure of an acceleration sensor as an electronic device according to an embodiment of the present invention will be described with reference to Figures 1 to 3. Figures 1 and 2 show a schematic configuration of an acceleration sensor as an example of an electronic device according to the present embodiment, with Figure 1 being a plan view and Figure 2 being a front cross-sectional view taken along line AA in Figure 1.

As shown in Figures 1 and 2, the acceleration sensor 100 according to this embodiment includes a base body 10, a groove portion 15, wiring 20, an external connection terminal 30, a cover body 50, a bonding material 60, a functional element 80, and a gap member 90.

The acceleration sensor 100 also includes grooves 16, 17, wiring 22, 24, external connection terminals 32, 34, a through hole 58, and a sealing member 70. For convenience, FIG. 1 shows the cover 50, the through hole 58, and the sealing member 70 in a see-through manner.

(Base)
The base 10 is made of glass (borosilicate glass). The material of the base 10 is not limited to glass, and may be, for example, silicon. As shown in Fig. 2, the base 10 has an upper surface (hereinafter referred to as a first surface 11) of the base 10 and a lower surface (hereinafter referred to as a second surface 12) opposite to the first surface 11. A recess 14 is provided on the first surface 11.

The movable part 86 and the movable electrode part 87 of the functional element 80 are arranged in the +Z-axis direction of the recess 14, and the movable part 86 and the movable electrode part 87 can move in the desired direction without being obstructed by the base body 10 due to the recess 14. In a plan view from the Z-axis direction, the shape of the recess 14 is not particularly limited, but is rectangular in this embodiment.

The groove portion 15 is provided on the first surface 11 of the base body 10 and extends from the inside to the outside of the internal space 56 surrounded by the base body 10 and the lid body 50. The groove portion 15 has a planar shape that corresponds to the planar shapes of the wiring 20 and the external connection terminal 30, for example.

Similarly, the grooves 16 and 17 are provided on the first surface 11 of the base 10 so as to follow the outer periphery of the recess 14. More specifically, the groove 16 extends in the -X-axis direction from the external connection terminal 32, along the outer periphery of the recess 14, passing through the +Y-axis side and -X-axis side of the recess 14, to the fixed electrode portion 88 that is located on the extreme +X-axis side of the -Y-axis side.

The groove portion 17 extends from the external connection terminal 34 in the -X-axis direction, along the outside of the groove portion 16, through the +Y-axis side and -X-axis side of the recess 14, and up to the fixed electrode portion 89, which is located on the extreme +X-axis side of the -Y-axis side.

The depth (size in the Z-axis direction) of the grooves 15, 16, and 17 is greater than the thickness (size in the Z-axis direction) of the wiring 20, 22, and 24 and the external connection terminals 30, 32, and 34. This makes it possible to prevent the wiring 20, 22, and 24 and the external connection terminals 30, 32, and 34 from protruding in the +Z-axis direction from the first surface 11.

(wiring)
The wiring 20 is provided in the groove 15. Specifically, the wiring 20 is provided on the surface of the base 10 that defines the bottom surface of the groove 15. The wiring 20 electrically connects the functional element 80 and the external connection terminal 30. The wiring 20 is connected to a fixing portion 81 of the functional element 80 via a contact portion 40 provided in the groove 15.

The wiring 22 is provided in the groove 16. Specifically, the wiring 22 is provided on the surface of the base 10 that defines the bottom surface of the groove 16. The wiring 22 electrically connects the functional element 80 and the external connection terminal 32. The wiring 22 is connected to the fixed electrode portion 88 of the functional element 80 via the contact portion 42.

The wiring 24 is provided in the groove 17. Specifically, the wiring 24 is provided on the surface of the base 10 that defines the bottom surface of the groove 17. The wiring 24 electrically connects the functional element 80 and the external connection terminal 34. The wiring 24 is connected to the fixed electrode portion 89 of the functional element 80 via the contact portion 44.

The external connection terminal 30 is provided on the wiring 20 in the groove portion 15. The external connection terminal 30 is disposed outside the internal space 56 and is provided at a position overlapping with the terminal hole 55 of the lid body 50 in a plan view seen from the Z-axis direction. The terminal hole 55 is a hole that penetrates the lid body 50 in the Z-axis direction to connect an external device (not shown) to the external connection terminal 30.

Similarly, the external connection terminal 32 is provided on the wiring 22 in the groove 16, and the external connection terminal 34 is provided on the wiring 24 in the groove 17. The external connection terminals 32 and 34 are disposed outside the internal space 56. The external connection terminals 30, 32, and 34 are disposed side by side along the Y-axis direction.

The wiring 20, 22, 24 and the external connection terminals 30, 32, 34 are made of materials such as ITO (Indium Tin Oxide), aluminum, gold, platinum, titanium, tungsten, chromium, etc. The contact portions 40, 42, 44 are made of materials such as gold, copper, aluminum, platinum, titanium, tungsten, chromium, etc.

If the wiring 20, 22, 24 and the external connection terminals 30, 32, 34 are made of a transparent electrode material such as ITO, and if the base 10 is transparent, then, for example, foreign matter present on the wiring 20, 22, 24 or the external connection terminals 30, 32, 34 can be easily confirmed from the second surface 12 side of the base 10.

In the above, an acceleration sensor 100 having three wirings 20, 22, and 24 and three external connection terminals 30, 32, and 34 has been described as an example, but the number of wirings and external connection terminals can be changed as appropriate depending on the shape and number of functional elements 80.

(Lid)
The lid 50 is bonded onto the first surface 11 of the base 10 via a bonding material 60, covers the functional element 80, and forms an internal space 56 between the lid 50 and the base 10. The lid 50 is made of silicon.

The lid 50 has an upper surface (hereinafter referred to as the third surface 51) of the lid 50 and a lower surface (hereinafter referred to as the fourth surface 52) opposite the third surface 51. A recess 57 is provided in the fourth surface 52. The recess 57 of the lid 50 also has a fifth surface 54 that defines an internal space 56 that houses the functional element 80. The internal space 56 is sealed in an inert gas atmosphere such as nitrogen gas or in a reduced pressure state.

The protrusion 53 is a portion of the lid body 50 that protrudes in the -Z axis direction and is provided on the outer periphery of the lid body 50.

(Joint material)
The base 10 and the lid 50 are joined at a joint 61 by a bonding material 60 .
The bonding material 60 may be, for example, low-melting glass. The bonding material 60 is not particularly limited, and may be, for example, lead silicate (PbO-SiO ₂ ) salt, boric acid (B ₂ O ₃ ) salt, phosphoric acid (P ₂ O ₅ ) salt, germanic acid (GeO ₂ ) salt, thallium acid (Tl ₂ O) salt, molybdenum acid (MoO ₃ ) salt, telluric acid (TeO ₂ ) salt, vanadium acid (V ₂ O ₅ ) salt, etc.

One of these may be used alone or two or more may be used in combination, that is, mixed or laminated. The constituent material of the bonding material 60 may be appropriately determined depending on the materials of the base body 10 and the lid body 50.

(Through hole)
The through-hole 58 penetrates the lid body 50 in the Z-axis direction from the third surface 51 to the fifth surface 54 of the lid body 50, and communicates with the internal space 56. The through-hole 58 has a tapered shape in which the opening diameter becomes smaller from the third surface 51 toward the fifth surface 54.

This prevents the solder balls from falling when melting them, as described below. In addition, the opening area becomes narrower from the third surface 51 toward the fifth surface 54, allowing for more reliable sealing.

The sealing member 70 is disposed within the through hole 58 and blocks the through hole 58. The internal space 56 is sealed by the sealing member 70. The material of the sealing member 70 is, for example, an alloy such as AuGe, AuSi, AuSn, SnPb, PbAg, SnAgCu, or SnZnBi.

By providing the through-hole 58 and the sealing member 70, the internal space 56 can be filled with an inert gas atmosphere such as nitrogen gas through the through-hole 58. In addition, the degree of vacuum in the internal space 56 can be adjusted through the through-hole 58.

(Functional element)
The functional element 80 is housed in the internal space 56 and is joined to the first surface 11 of the base body 10. In the following, a case will be described in which the functional element 80 is an acceleration sensor element (capacitive MEMS acceleration sensor element) that detects acceleration in the horizontal direction (X-axis direction).

The functional element 80 includes fixed portions 81 and 82, connecting portions 84 and 85, a movable portion 86, a movable electrode portion 87, and fixed electrode portions 88 and 89. The material of the functional element 80 is silicon that has been doped with impurities such as phosphorus or boron to give it electrical conductivity.

The fixing parts 81 and 82 are joined to the first surface 11 of the base 10. The fixing parts 81 and 82 are arranged to straddle the outer periphery of the recess 14 in a plan view from the Z-axis direction.

The connecting parts 84 and 85 connect the movable part 86 to the fixed parts 81 and 82. The connecting parts 84 and 85 have a desired spring constant and are configured so that the movable part 86 is displaced in the X-axis direction.

The connecting portion 84 is composed of two beams 84a and 84b that extend in the X-axis direction while meandering in the Y-axis direction. Similarly, the connecting portion 85 is composed of two beams 85a and 85b that extend in the X-axis direction while meandering in the Y-axis direction.

The movable part 86 is provided between the fixed part 81 and the fixed part 82. In a plan view seen from the Z-axis direction, the movable part 86 is a rectangle with its long side aligned along the X-axis direction.

The movable part 86 displaces in the +X-axis direction or the -X-axis direction while elastically deforming the connecting parts 84 and 85 in response to changes in acceleration in the X-axis direction. With this displacement, the size of the gap between the movable electrode part 87 and the fixed electrode part 88, and the size of the gap between the movable electrode part 87 and the fixed electrode part 89 change.

In other words, as a result of this displacement, the magnitude of the capacitance between the movable electrode portion 87 and the fixed electrode portion 88, and the magnitude of the capacitance between the movable electrode portion 87 and the fixed electrode portion 89 change. Based on these changes in capacitance, the functional element 80 can detect acceleration in the X-axis direction.

The movable electrode portions 87 are connected to the movable portion 86 and are provided in multiple numbers. The movable electrode portions 87 protrude from the movable portion 86 in the +Y-axis direction and the -Y-axis direction, and are arranged along the X-axis direction to form a comb-tooth shape.

The fixed electrode parts 88 and 89 have one end joined to the first surface 11 of the base 10 as a fixed end, and the other end extending toward the movable part 86 as a free end. The fixed electrode part 88 is electrically connected to the wiring 22, and the fixed electrode part 89 is electrically connected to the wiring 24.

The fixed electrode parts 88, 89 are arranged alternately in the X-axis direction to form a comb-like shape. The fixed electrode parts 88, 89 are arranged opposite the movable electrode part 87 at a distance, with the fixed electrode part 88 located on the -X-axis side of the movable electrode part 87 and the fixed electrode part 89 located on the +X-axis side.

The fixed parts 81 and 82, the connecting parts 84 and 85, the movable part 86, and the movable electrode part 87 are integrally formed.

When the material of the base 10 is glass containing alkali metal ions and the material of the functional element 80 is silicon, for example, the method of bonding the base 10 and the functional element 80 (fixed portions 81, 82 and fixed electrode portions 88, 89) can be anodic bonding. In this embodiment, the base 10 and the functional element 80 are bonded by anodic bonding.

In the acceleration sensor 100, the capacitance between the movable electrode portion 87 and the fixed electrode portion 88 can be measured by using the external connection terminals 30 and 32. Furthermore, in the acceleration sensor 100, the capacitance between the movable electrode portion 87 and the fixed electrode portion 89 can be measured by using the external connection terminals 30 and 34.

In this way, the acceleration sensor 100 can measure the capacitance between the movable electrode portion 87 and the fixed electrode portion 88, and the capacitance between the movable electrode portion 87 and the fixed electrode portion 89 separately, and detect acceleration with high accuracy based on these measurement results.

In the above, the functional element 80 is described as an acceleration sensor element that detects acceleration in the X-axis direction, but the functional element 80 may be an acceleration sensor element that detects acceleration in the Y-axis direction, or an acceleration sensor element that detects acceleration in the vertical direction (Z-axis direction).

Furthermore, the functional element 80 is not limited to an acceleration sensor element, but may be, for example, a gyro sensor element that detects angular velocity, or a pressure sensor element that detects pressure. Furthermore, the acceleration sensor 100 may be equipped with multiple such functional elements 80, or may combine elements having different functions.

(Gap member)
Next, the gap member 90 will be described with reference to Fig. 2 and Fig. 3. Fig. 3 is an enlarged front cross-sectional view of the gap member and the protrusion portion of Fig. 2. As shown in Fig. 2 and Fig. 3, the gap member 90 of this embodiment is disposed on the outer side of the functional element 80 on the first surface 11 of the base body 10 in a plan view seen from the Z-axis direction, at a position facing the functional element 80, and is provided in contact with the first surface 11 of the base body 10 and the fourth surface 52 of the cover body 50.

The length h1 of the gap member 90 in the Z-axis direction (hereinafter referred to as the height) is greater than the height of the bonding material 60, i.e., the distance h2 between the base 10 and the lid 50 (h1>h2). The height h3 of the protrusion 53 is less than the height h1 of the gap member 90 (h1>h3). The height h2 of the bonding material 60 combined with the height h3 of the protrusion 53 equals the height h1 of the gap member 90 (h1=h2+h3).

The height h2 of the bonding material 60 (the distance between the base 10 and the lid 50) is determined from the viewpoint of the bonding strength between the base 10 and the lid 50. In this embodiment, the height h2 of the bonding material 60 (the distance between the base 10 and the lid 50) is about 10 μm.

Similarly, the height h3 of the protrusion 53 is determined taking into account the thickness of the functional element 80. The height h1 of the gap member 90 is determined by the height h2 of the bonding material 60 (the distance between the base 10 and the lid 50) and the height h3 of the protrusion 53.

In this case, the height h1 of the gap member 90 may be the same as the thickness of the functional element 80. As an example, if the height h2 of the bonding material 60 (the distance between the base 10 and the lid 50) is 10 μm and the height h3 of the protrusion 53 is 20 μm, the height h1 of the gap member 90 is 30 μm.

It is also desirable that the length (hereinafter referred to as width) W1 of the gap member 90 in the Y-axis direction is approximately 50 μm, the width W2 of the bonding material 60 is approximately 200 μm, and the width W3 of the protrusion 53 is approximately 200 μm.

If the width W1 of the gap member 90, the width W2 of the bonding material 60, and the width W3 of the protrusion 53 are too large, they may come into contact with the functional element 80, which may reduce detection accuracy. On the other hand, if the width W1 of the gap member 90, the width W2 of the bonding material 60, and the width W3 of the protrusion 53 are too small, it is difficult to determine the height h2 of the bonding material 60 (the distance between the base 10 and the lid 50).

The material of the gap member 90 can be, for example, glass (borosilicate glass) or silicon. The gap member 90 may be made of the same material as the functional element 80, and may be made of, for example, silicon that has been doped with impurities such as phosphorus or boron to give it electrical conductivity.

[Manufacturing method of acceleration sensor]
Next, a method for manufacturing the acceleration sensor 100 as an electronic device according to this embodiment will be described with reference to Figs. 4 to 10. Fig. 4 is a flow chart showing an outline of the method for manufacturing the acceleration sensor according to this embodiment. Figs. 5 to 10 are process flow diagrams (front cross-sectional views showing the acceleration sensor in each process) showing the method for manufacturing the acceleration sensor, with Fig. 5 showing process flow 1, Fig. 6 showing process flows 2 and 4, Fig. 7 showing process flow 3, Fig. 8 showing process flow 5, Fig. 9 showing process flow 6, and Fig. 10 showing process flow 7. The cross-sectional positions in each of Figs. 5 to 10 are the same as those in Fig. 2.

As shown in FIG. 4, the manufacturing method of the acceleration sensor 100 includes the following preparatory steps: a base preparation step (step S101), a silicon substrate preparation step (step S102), and a lid preparation step (step S103).

The manufacturing method of the acceleration sensor 100 also includes a first bonding step (step S104), an etching step (step S105), and a second bonding step (step S106). Furthermore, the manufacturing method of the acceleration sensor 100 may also include a sealing step (step S107).

(1) Substrate preparation process (step S101)
As shown in Fig. 5, the base body 10 is prepared. The recess 14 and the grooves 15, 16, and 17 are formed on the first surface 11 of the base body 10 (see Fig. 1). The substrate 10 is formed by, for example, photolithography and etching techniques. The substrate 10 is made of, for example, borosilicate glass containing alkali metal ions.

Wirings 20, 22, and 24 are formed in the grooves 15, 16, and 17, respectively. Next, an external connection terminal 30 and a contact portion 40 are formed on the wiring 20 on the first surface 11 side of the base 10 so as to be electrically connected to the wiring 20.

Similarly, an external connection terminal 32 and a contact portion 42 are formed on the wiring 22 so as to be electrically connected to the wiring 22 (see FIG. 1). Also, an external connection terminal 34 and a contact portion 44 are formed on the wiring 24 so as to be electrically connected to the wiring 24 (see FIG. 1).

The wirings 20, 22, and 24 are formed, for example, by forming a conductive layer (not shown) by a method such as sputtering or CVD (Chemical Vapor Deposition), and then patterning the conductive layer. The patterning is performed by photolithography and etching techniques.

As another method, a lift-off method can be used in which a conductive film is formed after patterning with photoresist, and unnecessary film is peeled off at the same time as the photoresist to form wiring.
The external connection terminals 30, 32, and 34 and the contact portions 40, 42, and 44 are formed, for example, in the same manner as the wirings 20, 22, and 24.

Through the above steps, a base 10 is prepared that includes a recess 14, wiring 20, 22, 24, external connection terminals 30, 32, 34, and contact portions 40, 42, 44, etc.

(2) Silicon substrate preparation process (step S102)
As shown in FIG. 6, a silicon substrate 8 serving as an original substrate for forming a functional element 80 is prepared by placing it on a base 10 .

(3) Lid preparation process (step S103)
As shown in Fig. 7, a lid 50 is prepared. The lid 50 may be made of, for example, silicon or glass. A recess 57 that forms an internal space 56 between the base 10 and the lid 50, and a through hole 58 that penetrates from the third surface 51 to the fifth surface 54 are formed. The recess 57 and the through hole 58 may be formed by photolithography and etching.

(4) First joining process (step S104)
6, the silicon substrate 8 prepared in the silicon substrate preparation step (step S102) is bonded to the base body 10 by anodic bonding. As a condition for the anodic bonding, for example, it is preferable to apply a DC voltage of about 800 V to 1 kV while heating to about 300° C.
The heating temperature for the anodic bonding can be in the range of about 250° C. to 500° C. Thus, the region where the base body 10 and the silicon substrate 8 are in contact with each other is bonded.

By anodically bonding the base body 10 and the silicon substrate 8 (functional element 80), the bonding strength can be increased and a stable bond can be achieved. This makes it possible to perform etching and other processes on the silicon substrate 8.

(5) Etching process (step S105)
As shown in FIG. 8, the silicon substrate 8 anodically bonded to the base body 10 in the first bonding process (step S104) is patterned to form a functional element 80 (see FIGS. 1 and 2) and a gap member 90 (see FIGS. 1 and 2).

The patterning can be performed using photolithography and dry or wet etching. Preferably, a dry etching method using inductively coupled plasma (ICP) technology is used. Note that the silicon substrate 8 may be thinned to a desired thickness before patterning.

(6) Second bonding process (step S106)
As shown in FIG. 9, low-melting-point glass is applied as a bonding material 60 to the underside of the protrusion 53 of the lid 50 prepared in the lid preparation step (step S103) by screen printing, and the lid 50 is bonded to the base 10.

Specifically, the lid body 50 houses the functional element 80 formed in the etching process (step S105) in the internal space 56, and one end of the gap member 90 abuts against the surface of the base body 10 facing the lid body 50, and the other end of the gap member 90 abuts against the surface of the lid body 50 facing the base body 10. At this time, it is preferable that the height of the gap member 90 is greater than the thickness of the bonding material 60.

Then, the base 10 and the lid 50 are stacked with the low-melting point glass between them and heat treated. This increases the bonding strength between the base 10 and the lid 50 via the low-melting point glass, and allows for stable bonding. This ensures that the lid 50 provides an airtight seal.

(7) Sealing process (step S107)
10, the atmosphere in the internal space 56 is adjusted by the through-hole 58, and the internal space 56 is sealed by closing the through-hole 58 with a sealing member 70. At this time, for example, the internal space 56 may be filled with an inert gas (nitrogen gas) atmosphere through the through-hole 58, or may be in a reduced pressure state.

For example, if the functional element 80 is an acceleration sensor element, it is desirable that the internal space 56 be in a reduced pressure state. This can prevent the vibration phenomenon of the acceleration sensor element from being damped by air viscosity.

Specifically, a spherical solder ball (not shown) is placed in the through hole 58, and the solder ball is melted by irradiation with laser light to form the sealing member 70.

Even if the through-hole 58 is not provided, the internal space 56 can be in a reduced pressure state by performing the second bonding step (step S106) in a reduced pressure atmosphere, thereby simplifying the process.
Through the above steps, the acceleration sensor 100 can be manufactured.

In the above embodiment, the first bonding step (step S104) is described as using anodic bonding. However, the electronic device manufacturing method according to the present invention can be applied to manufacturing methods that perform multiple anodic bonding operations, and can also be applied to manufacturing methods that perform more than two anodic bonding operations (three or more operations).

In addition, although the above describes a method using anodic bonding in the first bonding step, the present invention can also be applied to bonding methods that do not use other adhesive materials. Specifically, the present invention can also be applied to direct bonding techniques that require flatness and cleanliness of the bonding surfaces, such as low-temperature plasma activation bonding.

As described above, the acceleration sensor 100 according to this embodiment can provide the following effects.
(1) Since the gap member 90 is included which is in contact with the surface 11 of the base 10 facing the lid body 50 and the fourth surface 52 of the lid body 50 facing the base 10, when the base 10 and the lid body 50 are joined together via the joining material 60 (low-melting point glass), the height of the gap member 90 determines the distance h2 between the base 10 and the lid body 50.
As a result, regardless of the amount of bonding material 60 applied to the joint 61, the bonding material 60 can be reliably inserted at a constant height (amount) between the base 10 and the lid 50. In other words, even if the amount of bonding material 60 applied to the joint 61 is greater than the specified amount, the gap h2 between the base 10 and the lid 50 can be prevented from becoming large.
Furthermore, even if the amount of bonding material 60 applied to the bonding portion 61 is less than the specified amount, it is possible to prevent the gap h2 between the base body 10 and the lid body 50 from becoming smaller. As a result, the gap h2 between the base body 10 and the lid body 50 can be kept constant and bonded reliably, thereby reducing deterioration in bonding strength and providing a highly reliable acceleration sensor 100.

(2) Because the gap member 90 and the functional element 80 are made of the same material, no manufacturing process is required just to form the gap member 90, and the gap member 90 can be obtained without increasing costs.

(3) Because the gap member 90 and the functional element 80 are made of silicon, the gap member 90 and the functional element 80 can be easily formed together from the same substrate, thereby reducing costs.

(4) Since the gap member 90 is arranged surrounding the functional element 80, when the base body 10 and the lid body 50 are joined via the low-melting point glass, the height h1 of the gap member 90 determines the distance h2 between the base body 10 and the lid body 50 around the functional element 80.
As a result, regardless of the amount of bonding material 60 applied to the bonding portion 61, the bonding material 60 can be reliably inserted at a constant height (amount) between the base 10 and the lid 50 around the periphery of the functional element 80. As a result, the base 10 and the lid 50 can be reliably bonded to each other.

(5) Since the gap member 90 contains silicon, it is possible to apply processing techniques used in the manufacture of silicon semiconductor devices when forming the gap member 90. As a result, the gap member 90 can be formed finely and with high precision.

(6) Because the lid body 50 contains silicon, it is possible to apply processing techniques used in the manufacture of silicon semiconductor devices when forming the lid body 50. As a result, the lid body 50 can be formed finely and with high precision.

(7) Since the substrate 10 is formed containing glass, there is no need to interpose an insulating film on the substrate 10 when maintaining insulation between the substrate 10 and the functional element 80, and insulation separation can be easily achieved.

(8) The base 10 and the lid 50 are joined using low-melting-point glass, so they can be joined at low temperatures. As a result, exposure of the base 10 and the lid 50 to high temperatures is reduced, and damage can be suppressed.

(Variation 1)
Fig. 11 is a front cross-sectional view showing an enlarged view of the gap member and the protrusions of the acceleration sensor according to the modified example 1. In the above embodiment, the acceleration sensor 100 is described as including the gap member 90 in contact with the surface of the base 10 facing the lid 50 and the surface of the lid 50 facing the base 10 as shown in Fig. 2, but is not limited to this configuration.
The following describes the acceleration sensor 200 according to Modification 1. Note that the same components as those in the embodiment are given the same reference numbers, and duplicated descriptions will be omitted.

The gap member 290 is formed integrally with the lid body 250 and is made of a material such as glass (borosilicate glass) or silicon.

In the manufacturing method of the acceleration sensor 200 according to this modified example, the gap member 90 is not formed in the etching process (step S105) described in the embodiment, but the gap member 290 is formed in the lid preparation process (step S103). Photolithography and etching techniques can be used for the formation.

As described above, the acceleration sensor 200 according to this modified example can provide the following effects in addition to those of the embodiment.

Because the gap member 290 is integrated with the lid body 250, the gap member 290 and the lid body 250 can be easily formed together from the same substrate, thereby reducing costs.

In addition, in the above embodiment, the gap members 90 are not limited to being arranged on two sides facing each other across the functional element 80. Figures 12 to 16 are schematic plan views showing the arrangement of the gap members 90 according to modified examples.

(Variation 2)
12 , in the above acceleration sensor, the gap member 90 may be provided along at least one corner of the functional element 80. In FIG. 12 , the gap member 90 is disposed at each of the four corners of the functional element 80.

(Variation 3)
13, in the above acceleration sensor, the gap members 90 may be provided at diagonally opposing positions of the functional element 80. Fig. 13 shows an example in which the gap members 90 are provided at a corner portion of the functional element 80 in the +X-axis direction and in the +Y-axis direction, and at a corner portion of the functional element in the -X-axis direction and in the -Y-axis direction.

(Variation 4)
As shown in FIG. 14 , in the acceleration sensor described above, the gap member 90 may be provided along the periphery of the functional element 80 .

(Variation 5)
As shown in FIG. 15, in the acceleration sensor described above, the gap member 90 may be provided outside the functional element 80 along the X-axis and Y-axis directions.

(Variation 6)
As shown in FIG. 16, in the acceleration sensor described above, the gap members 90 may be provided at positions that sandwich the functional element 80 along the X-axis direction.

[Electronic devices]
Next, an electronic device equipped with the above electronic device will be described. Fig. 17 is a perspective view showing a typical configuration of a mobile (or notebook) personal computer as an example of an electronic device equipped with the electronic device.

As shown in FIG. 17, the personal computer 1100 is composed of a main body 1104 having a keyboard 1102 and a display unit 1106 having a display unit 1101, and the display unit 1106 is rotatably supported on the main body 1104 via a hinge structure. Such a personal computer 1100 has the electronic device described above (e.g., the acceleration sensor 100) built in.

Figure 18 is a perspective view showing a schematic configuration of a mobile phone (including a PHS) as an electronic device equipped with the above electronic device. As shown in Figure 18, a mobile phone 1200 has a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206, and a display unit 1201 is disposed between the operation buttons 1202 and the earpiece 1204. Such a mobile phone 1200 has a built-in electronic device (e.g., an acceleration sensor 100).

Figure 19 is a perspective view showing a schematic configuration of a digital still camera as an electronic device equipped with the above electronic device (e.g., acceleration sensor 100). Note that Figure 19 also shows a simplified diagram of connections to external devices.

Here, while a normal camera exposes silver halide photographic film to the light image of the subject, the digital still camera 1300 photoelectrically converts the light image of the subject using an imaging element such as a CCD (Charge Coupled Device) to generate an imaging signal (image signal).

A display unit 1310 is provided on the rear (front side in the figure) of the case (body) 1302 of the digital still camera 1300, and is configured to display images based on image signals captured by the CCD. The display unit 1310 functions as a viewfinder that displays the subject as an electronic image.

In addition, a light receiving unit 1304 including an optical lens (image pickup optical system) and a CCD is provided on the front side (rear side in the figure) of the case 1302. When the photographer checks the subject image displayed on the display unit 1310 and presses the shutter button 1306, the image pickup signal of the CCD at that time is transferred to and stored in the memory 1308.

In addition, in this 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.
A television monitor 1430 is connected to the video signal output terminal 1312, and a personal computer 1440 is connected to the data communication input/output terminal 1314, respectively, as required.

Furthermore, by performing a predetermined operation, the image signal stored in the memory 1308 is output to a television monitor 1430 or a personal computer 1440. Such a digital still camera 1300 has a built-in electronic device.

Since such electronic devices are equipped with the electronic devices described above, they achieve the effects described in the above embodiments, are compact, and are highly reliable.

In addition to these, examples of electronic devices equipped with the above electronic devices include inkjet discharge devices (e.g., inkjet printers), laptop personal computers, televisions, video cameras, video tape recorders, various navigation devices, pagers, electronic organizers (including those with communication functions), electronic dictionaries, calculators, electronic game machines, word processors, workstations, videophones, security television monitors, electronic binoculars, POS terminals, medical equipment (e.g., electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasound diagnostic devices, electronic endoscopes), fish finders, various measuring devices, instruments, flight simulators, etc.

In either case, since these electronic devices are equipped with the above electronic devices, the effects described in the above embodiments are reflected and the electronic devices are highly reliable.

[Mobile object]
Next, a moving object equipped with the above electronic device will be described. Fig. 20 is a perspective view showing a model of an automobile as an example of a moving object. The above electronic device is mounted on an automobile 1500.

For example, as shown in FIG. 20, an automobile 1500 as a moving object has an electronic control unit 1502 mounted on a vehicle body 1501, which has a built-in electronic device (e.g., acceleration sensor 100) and controls tires 1503 and the like. Thus, since the automobile 1500 is equipped with the electronic device, the effects described in the above embodiment are reflected, and the automobile 1500 has excellent reliability.

The above electronic devices can also be widely applied to electronic control units (ECUs) in keyless entry, immobilizers, car navigation systems, car air conditioners, anti-lock braking systems (ABS), airbags, tire pressure monitoring systems (TPMS), engine controls, battery monitors for hybrid and electric vehicles, and vehicle attitude control systems.

The electronic device described above can be suitably used as an attitude detection sensor for moving objects including not only the automobile 1500, but also self-propelled robots, self-propelled transport equipment, trains, ships, airplanes, and artificial satellites, and in any case, the effects described in the above embodiment are reflected, making it possible to provide a highly reliable moving object.

The electronic device described above is not limited to the acceleration sensor 100, but may be an angular velocity sensor in which a functional element has an angular velocity detection function, a pressure sensor in which a functional element has a pressure detection function, a weight sensor in which a functional element has a weight detection function, or a composite sensor that combines these sensors (including an acceleration sensor).
The electronic device may also be a vibrator in which the functional element is a vibrating piece, an oscillator, a frequency filter, or the like.

8...silicon substrate, 10...base, 11...first surface, 12...second surface, 14...recess, 15, 16, 17...groove, 20, 22, 24...wiring, 30, 32, 34...external connection terminal, 40, 42, 44...contact portion, 50...lid, 51...third surface, 52...fourth surface, 53...projection portion, 54...fifth surface, 55...terminal hole, 56...internal space, 57...recess, 58...through hole, 60 ...bonding material, 61...bonding portion, 70...sealing member, 80...functional element, 81...fixed portion, 82...fixed portion, 84...connecting portion, 84a...beam, 85...connecting portion, 85a...beam, 86...movable portion, 87...movable electrode portion, 88...fixed electrode portion, 89...fixed electrode portion, 90...gap member, 100...acceleration sensor as electronic device, 200...acceleration sensor, 250...lid, 290...gap Spacer, 1100...personal computer as electronic device, 1101...display section, 1102...keyboard, 1104...main body, 1106...display unit, 1200...mobile phone as electronic device, 1201...display section, 1202...operation buttons, 1204...earpiece, 1206...mouthpiece, 1300...digital still camera as electronic device, 1302...case, 1304...light receiving unit, 1306...shutter button, 1308...memory, 1310...display section, 1312...video signal output terminal, 1314...input/output terminal, 1430...television monitor, 1440...personal computer, 1500...automobile as mobile object, 1501...vehicle body, 1502...electronic control unit, 1503...tires.

Claims (14)

When the three mutually orthogonal axes are the X-axis, the Y-axis, and the Z-axis,
a base including a first surface and a second surface that are perpendicular to the Z axis and have a front-back relationship with each other, the base having a functional element integrated on the first surface side that detects a physical quantity based on a change in capacitance ;
a cover including a third surface and a fourth surface that are perpendicular to the Z axis and have a front-back relationship with each other, the cover having a recess on the fourth surface side ;
a bonding material bonding the first surface of the base body and the fourth surface of the lid body such that the recess overlaps the functional element in a plan view from a Z-axis direction along the Z-axis;
a gap member disposed between the first surface and the fourth surface;
Including ,
The functional element is
It is made of silicon that has been doped with impurities to give it electrical conductivity,
The gap member is
A space is provided between the bonding material and the adhesive.
A capacitive MEMS sensor comprising: a first surface and a fourth surface ; In claim 1,
A capacitive MEMS sensor, characterized in that , in the plan view, the gap member surrounds the functional element . In claim 1 or 2,
the lid body includes a protrusion protruding from the first surface side toward the fourth surface side,
The capacitive MEMS sensor is characterized in that the bonding material is provided between the protrusion and the fourth surface . In claim 3,
The capacitive MEMS sensor is characterized in that the protrusion is spaced apart from the gap member . In claim 3 or 4,
The thickness of the bonding material in the Z-axis direction is
The length of the gap member along the Z-axis direction; and
A length of the protrusion along the Z-axis direction; and
A capacitive MEMS sensor characterized by being defined by : In any one of claims 1 to 5,
A capacitive MEMS sensor , characterized in that the length of the gap member along the Z-axis direction defines the distance between the first surface and the fourth surface . In any one of claims 1 to 6,
The capacitive MEMS sensor is characterized in that the gap member is integrated with the lid. In any one of claims 1 to 7,
The capacitive MEMS sensor is characterized in that the base body has wiring on the first surface that is connected to the functional element . In claim 8,
A capacitive MEMS sensor, characterized in that , in the plan view, the wiring intersects with the bonding material . In any one of claims 1 to 9,
The capacitive MEMS sensor is characterized in that the material of the gap member contains glass or silicon . In any one of claims 1 to 10,
The capacitive MEMS sensor is characterized in that the lid has a through hole that is sealed with a sealing member. In any one of claims 1 to 11,
The capacitive MEMS sensor is characterized in that the functional element is sealed in a vacuum state. 13. An electronic device comprising the capacitive MEMS sensor according to claim 1. A moving object comprising the capacitive MEMS sensor according to claim 1 .

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