Transducer

Abstract

To provide a highly reliable transducer which can be reliably bonded within a bonding area. [Solution] The transducer includes a first substrate, a second substrate, a functional element provided between the first substrate and the second substrate, and a metal eutectic layer that bonds the first substrate and the second substrate in a bonding region located around the functional element, and a recess is provided on a first surface of the second substrate facing the first substrate, and the recess has a second surface that is a bottom and a sidewall that connects the first surface and the second surface, and is provided with an insulating layer having a first portion provided on the first surface, a second portion provided on the sidewall, and a third portion provided on the second surface, and the insulating layer is provided on both sides of the bonding region.

Description

[Technical Field]

[0001] The present invention relates to a transducer. [Background technology]

[0002] Conventionally, a sensor device has been known that includes a base body having a cavity, a sensor element suspended within the cavity, and a lid body that seals the cavity. The base body and the lid body are bonded together via a bonding material. The bonding material is required to have high bonding strength and high long-term sealing reliability.

[0003] For example, Patent Document 1 discloses an inertial sensor that uses an AlGe eutectic as a bonding material. According to this document, the concentration of Ge in the AlGe eutectic is either uniform or a function of the distance from the lid or base. In particular, it is disclosed that the concentration of Ge becomes uniform when a long-term heat treatment is performed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2010 / 0059835 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology of Patent Document 1, there is a risk that the AlGe eutectic bonding material may spread beyond the bonding area or may scatter due to the heat treatment when forming the AlGe eutectic bonding material. In particular, if the AlGe eutectic scatters due to a long-term heat treatment, there is a risk that it may cause malfunction of the inertial sensor. The inertial sensor is an example of a transducer. In other words, there was a need for a highly reliable transducer that could be reliably bonded within the bonding area. [Means for solving the problem]

[0006] A transducer according to one embodiment of the present application includes a first substrate, a second substrate, a functional element disposed between the first substrate and the second substrate, and a metal eutectic layer that bonds the first substrate and the second substrate in a bonding region located around the functional element, wherein a recess is provided on a first surface of the second substrate facing the first substrate, and the recess has a second surface that is a bottom and a sidewall that connects the first surface and the second surface, and includes an insulating layer having a first portion provided on the first surface, a second portion provided on the sidewall, and a third portion provided on the second surface, and the insulating layer is disposed on either side of the bonding region. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a plan view of the transducer according to the first embodiment. [Figure 2] 2 is a cross-sectional view of the transducer taken along the bb section of FIG. 1. [Figure 3] Enlarged view of part c in Figure 2. [Figure 4] Enlarged view of part d in Figure 2. [Figure 5] FIG. 3 is a cross-sectional view of a main part of the base body and the lid body before bonding. [Figure 6] FIG. 2 is a perspective view of a main part showing the electrical wiring structure of a metal eutectic layer. [Figure 7] FIG. 4 is a flowchart showing the flow of a method for manufacturing the lid body. [Figure 8] 1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 9] 1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 10] 1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 11] 1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 12] 1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 13] 1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 14]1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 15] 1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 16] 1A to 1C are cross-sectional views of a main part showing one aspect of a manufacturing process. [Figure 17] FIG. 10 is a cross-sectional view of a bonding region according to one embodiment of the present invention. [Figure 18] 10A and 10B are cross-sectional views of different bonding regions. [Figure 19] A comparison table of contact resistance depending on whether or not a barrier layer is present. [Figure 20] FIG. 10 is a plan view of a transducer according to a third embodiment. [Figure 21] FIG. [Figure 22] FIG. [Figure 23] FIG. 10 is a perspective view of a transducer according to a fourth embodiment. [Figure 24] FIG. 2 is a plan view of a main part showing the configuration of a transducer. [Figure 25] FIG. 25 is a cross-sectional side view taken along the line dd in FIG. 24 . DETAILED DESCRIPTION OF THE INVENTION

[0008] Embodiment 1 ***Transducer Configuration*** Fig. 1 is a plan view of a transducer according to embodiment 1. Fig. 2 is a cross-sectional view of the transducer taken along the line bb in Fig. 1 . The configuration of a transducer 100 according to this embodiment will be described with reference to FIGS.

[0009] The transducer 100 is, for example, an acceleration sensor that detects acceleration in the vertical direction. Each figure illustrates three mutually orthogonal axes: the X-axis, the Y-axis, and the Z-axis. In this embodiment, the Z-axis direction is the vertical direction, but this is not limiting. The direction along the X-axis is referred to as the "X-direction," the direction along the Y-axis as the "Y-direction," and the direction along the Z-axis as the "Z-direction." The tip of the arrow in each axis direction is also referred to as the "plus side," and the base of the arrow is also referred to as the "minus side." For example, the Y-direction refers to both the positive and negative Y-directions. The positive Z-direction is also referred to as "up," and the negative Z-direction is also referred to as "down." In the following figures, dimensions and scales may differ from the actual dimensions for clarity.

[0010] The transducer 100 is a uniaxial acceleration sensor made of a MEMS (Micro Electro Mechanical Systems) device. Generally, a transducer refers to a converter that converts one physical quantity into another, and examples include electromechanical transducers, acoustic-electric transducers, and optoelectric transducers. The transducer according to one embodiment of the present application may be any transducer in which a base and a lid are joined by a bonding material, and may be an inertial sensor that converts acceleration or angular velocity into an electrical signal, a vibrator (timing device) in which mechanical vibrations are excited by an electrical signal, an ultrasonic sensor that converts an ultrasonic signal into an electrical signal, an RF filter that utilizes the electromechanical coupling coefficient of a piezoelectric material, a piezoelectric mirror, a piezoelectric actuator, a pressure sensor, or the like. In this first embodiment, an acceleration sensor, which is one type of inertial sensor, will be used as an example of a transducer. In an acceleration sensor in which a MEMS device element formed in a base is sealed with a lid, when acceleration is applied as an external force, an inertial force acts within the MEMS device element, causing a change in the capacitance value within the element. This change in capacitance is converted into an electrical signal using a differential detection circuit or the like and extracted as a sensor signal.

[0011] As shown in Figure 2, the transducer 100 is composed of a base 10 as a first substrate, a functional element 80 arranged on the base 10, a wiring layer 7 extending from the functional element 80, and a lid 30 as a second substrate covering the functional element 80. The base 10 is constructed by laminating an SOI (Silicon On Insulator) substrate consisting of a substrate 1, a buried insulating layer 2, and a semiconductor layer 3, an interlayer insulating layer 6, a wiring layer 7, and a surface insulating layer 8 in this order along the Z direction. The substrate 1 is a single crystal silicon substrate, and the buried insulating layer 2 is provided on its upper surface. The buried insulating layer 2 is preferably SiO2 formed by thermal oxidation.

[0012] The substrate 1 has a substrate recess 5 dug down from the peripheral edge. The substrate recess 5 is a cavity, and is one portion that forms a storage space S that stores a functional element 80. The substrate recess 5 allows a movable body 55 (FIG. 1) of the functional element 80 to oscillate. Note that although FIG. 2 shows a buried insulating layer 2 provided on the bottom surface of the substrate recess 5, this may not be necessary. The semiconductor layer 3 is a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), or arsenic (As). In a preferred embodiment, the semiconductor layer 3 and the buried insulating layer 2 are bonded together by a Si-SiO2 SOI junction. Bonding via an insulating film such as SiO2 is also called direct bonding, fusion bonding, or permanent bonding.

[0013] The functional element 80 is an acceleration sensor element, and is formed by etching and patterning the semiconductor layer 3. In a preferred embodiment, a deep etching technique known as the Bosch process is used. The functional element 80 is fixed to the substrate 1 by a fixing portion 65 (FIG. 1). In this embodiment, the functional element 80 is an acceleration sensor element, but it may also be another type of sensor element, a vibration element that constitutes a vibrator, or a piezoelectric mirror element that constitutes a piezoelectric mirror. As a preferred example, the lid 30 uses a silicon substrate. The surface of the lid 30 facing the functional element 80 is referred to as the inner surface 30b, and the surface opposite the inner surface 30b is referred to as the outer surface 30a. The inner surface 30b corresponds to the first surface. The inner surface 30b of the lid 30 is provided with a lid recess 35 dug down from the periphery. The lid recess 35 is a cavity and is one portion that forms the storage space S for storing the functional element 80. That is, the storage space S is formed by the substrate recess 5 and the lid recess 35. The lid recess 35 is provided with a stopper portion 29, which is a protrusion that restricts excessive oscillation of the movable body 55 of the functional element 80. The base 10 and the lid 30 are bonded by a metal eutectic layer 20 at a bonding region 25 provided on the periphery. The bonding method will be described in detail later.

[0014] The lid 30 also has a sealing hole 36 penetrating the lid. The sealing hole 36 serves to communicate between the outside air and the storage space S when the base 10 and the lid 30 are joined. The sealing hole 36 is formed in a recess recessed from the outer surface 30a of the lid 30, and can be sealed with, for example, a solder ball 37 after the base 10 and the lid 30 are joined. Alternatively, sealing can be performed by directly melting the lid 30 around the sealing hole 36 with laser light. By providing the sealing hole 36, outgassing and moisture generated from the base 10 and the lid 30 during the formation of the metal eutectic layer 20 can be released to the outside through the sealing hole 36. Thereafter, the sealing hole 36 is sealed with laser light, thereby maintaining a clean atmosphere within the storage space S. In a preferred embodiment, the storage space S is hermetically sealed with an inert gas such as nitrogen, helium, or argon. Preferably, the storage space S is at approximately atmospheric pressure or in a vacuum state in an operating temperature environment of approximately -50°C to 150°C. For example, if the functional element 80 is an acceleration sensor, the storage space S should be at a pressure close to atmospheric pressure, and if the functional element 80 is an angular velocity sensor, the storage space S should be at a vacuum pressure.

[0015] ***Configuration of functional elements*** As shown in FIG. 1, the functional element 80 is an acceleration sensor that detects acceleration in the Z direction, and employs a so-called one-sided seesaw structure in which the movable body 55 oscillates around an oscillating axis 61 as an axis. The functional element 80 is composed of a fixed part 65, a movable body 55 that is swingable around an oscillation axis 61 that passes through the center of the fixed part 65 and is along the Y-axis, and a first rotation spring 54a, a second rotation spring 54b, etc. that connect the fixed part 65 and the movable body 55. The fixed part 65 is fixed to a base part (not shown) that protrudes from the substrate 1 (FIG. 2). The periphery of the base part is a substrate recess 5 (FIG. 2), which allows the movable body 55 to swing. In FIG. 1, a line segment that is perpendicular to the oscillation axis 61 and that passes through the center of the functional element 80 along the X-axis is defined as a center line 60.

[0016] The movable body 55 has a first bar 52a extending in the X-positive direction from the first rotation spring 54a, a second bar 52b extending in the X-positive direction from the second rotation spring 54b, and a third bar 53 connecting the first bar 52a and the second bar 52b. The third bar 53 is provided with four comb-shaped movable electrode groups 73a to 73d. The movable electrode group 73a is composed of six movable electrodes 71c extending in the positive X direction from the third bar 53 on the negative Y side of the center line 60. The movable electrode group 73b is composed of six movable electrodes 71c extending in the negative X direction from the third bar 53 on the negative Y side of the center line 60. Note that the number of movable electrodes 71c is not limited to six, and any number may be used as long as it is plural. The movable electrode groups 73c and 73d are provided at positions that are line-symmetrical to the movable electrode groups 73a and 73b on the Y positive side, with the center line 60 as the axis of symmetry.

[0017] On the substrate 1 (FIG. 2) side, a group of fixed electrodes 74a to 74d are provided so as to face the group of movable electrodes 73a to 73d. The fixed electrode group 74a is composed of a support portion 75a fixed to the substrate 1 and seven fixed electrodes 72 extending from the support portion 75a in the negative X direction. The fixed electrode group 74b is composed of a support portion 75b fixed to the substrate 1 and seven fixed electrodes 72 extending in the positive X direction from the support portion 75b. The number of fixed electrodes 74a, 74b is not limited to seven, but may be any number corresponding to the number of movable electrodes 71c. More preferably, fixed electrodes 74a, 74b are configured to surround movable electrode 71c on three sides. This cancels out unnecessary electrostatic attraction and enables accurate detection of the desired acceleration in the Z-axis direction. The fixed electrode groups 74c and 74d are provided at positions that are line-symmetrical to the fixed electrode groups 74a and 74b on the Y positive side, with the center line 60 as the axis of symmetry.

[0018] The detection unit formed by the fixed electrode group 74a and the movable electrode group 73a and the detection unit formed by the fixed electrode group 74b and the movable electrode group 73b are collectively referred to as an N-type detection unit 76n. In the N-type detection unit 76n, a parallel plate capacitance is formed by the fixed electrode 72 and the movable electrode 71c arranged opposite to each other. The capacitance changes in accordance with the change in the overlapping area between the fixed electrode 72 and the movable electrode 71c as the movable electrode 71c is displaced due to acceleration. Similarly, the detection unit formed by fixed electrode group 74c and movable electrode group 73c and the detection unit formed by fixed electrode group 74d and movable electrode group 73d are collectively referred to as P-type detection unit 76p. In P-type detection unit 76p, a parallel plate capacitance is formed by fixed electrode 72c and movable electrode 71, which are arranged opposite each other. This capacitance changes in accordance with the change in the overlapping area between fixed electrode 72c and movable electrode 71 as movable electrode 71 is displaced due to acceleration.

[0019] The movable electrodes 71c of the N-type detection portion 76n are thinner in the Z direction than the movable electrodes 71 of the P-type detection portion 76p. More specifically, the movable electrodes 71c are thinned by being cut out in a stepped pattern midway along the extension direction from the same thickness as the base third bar 53. As a result, the thickness of each of the twelve movable electrodes 71c on the positive Z side is thinner in the portion facing the fixed electrode 72. The fixed electrodes 72c of the P-type detection unit 76p are thinner in the Z direction than the fixed electrodes 72 of the N-type detection unit 76n. More specifically, the fixed electrodes 72c are thinned by being cut out in a stepped pattern midway along the extension direction from the thickness at the base on the support portions 75c, 75d side. As a result, the thickness of all 14 fixed electrodes 72c on the positive Z side is thinner in the portion facing the movable electrode 71.

[0020] With this configuration, when acceleration is applied in the positive Z direction, the movable body 55 is displaced in the negative Z direction due to inertial force, and the overlapping area of ​​the N-type detection unit 76n decreases. Meanwhile, the overlapping area of ​​the P-type detection unit 76p is maintained. Also, when acceleration is applied in the negative Z direction, the movable body 55 is displaced in the positive Z direction due to inertial force, and the overlapping area of ​​the N-type detection unit 76n is maintained while the overlapping area of ​​the P-type detection unit 76p decreases. Based on this correlation, the functional element 80 can detect acceleration in the plus / minus Z direction by differentially detecting the change in the overlapping area between the N-type detection portion 76n and the P-type detection portion 76p as a change in capacitance.

[0021] ***Terminals and Joint Areas*** 1, the base 10 has a substantially rectangular shape, and the short side in the negative X direction forms a protruding portion 11 that protrudes beyond the short side of the lid 30. The protruding portion 11 is provided with terminals 91 to 94 for external connection. The terminal 91 is a movable electrode terminal, and is electrically connected to all the movable electrodes 71 and 71c by the wiring 81. The terminal 92 is an N-type fixed electrode terminal, and is electrically connected to all the fixed electrodes 72 of the N-type detector 76n by wiring 82. The terminal 93 is a P-type fixed electrode terminal, and is electrically connected by wiring 83 to all of the fixed electrodes 72c of the P-type detection section 76p. The terminal 94 is a GND terminal, and is electrically connected to the metal eutectic layer 20 by the wiring 84. Details of the connection between the terminal 94 and the metal eutectic layer 20 will be described later. In other words, the wirings 81 to 84 pass through the bonding region 25 from outside the bonding region 25 and are electrically connected to the functional element 80.

[0022] The base 10 and the lid 30 are bonded by the metal eutectic layer 20 in a quadrangular annular bonding region 25 that surrounds the periphery of the functional element 80. The bonding region 25 is provided along a recess 34 of the lid 30. As shown in FIG. 2, the recess 34 is a groove provided on the inner surface 30b of the lid 30. The recess 34 is a cavity that is rectangular in cross section, and the metal eutectic layer 20 is provided within the recess 34. 1, the recess 34 is provided in a quadrangular ring shape in plan view surrounding the periphery of the functional element 80. The bonding region 25 is a region in the recess 34 where the metal eutectic layer 20 is provided. The metal eutectic layer 20 intersects with the wirings 81 to 83 in plan view. In other words, the transducer 100 includes a base 10 as a first substrate, a lid 30 as a second substrate, a functional element 80 provided between the base 10 and the lid 30, and a metal eutectic layer 20 that bonds the base 10 and the lid 30 in a bonding region 25 located around the functional element 80, and a recess 34 is provided on an inner surface 30b of the lid 30 as a first surface facing the base 10.

[0023] ***Details of the metal eutectic layer*** Fig. 3 is an enlarged view of part c in Fig. 2. Fig. 4 is an enlarged view of part d in Fig. 2. Fig. 5 is a cross-sectional view of the main parts of the base body and the lid body before bonding. 3 shows a cross section of a portion where the metal eutectic layer 20 overlaps with the underlying wiring 82. The wiring 82 extends from the terminal 92 to the functional element 80 side. The base 10 is formed by laminating, in order from the negative Z direction, a substrate 1, a buried insulating layer 2, a semiconductor layer 3, an interlayer insulating layer 6, a wiring layer 7 including wiring 82, a surface insulating layer 8, and a barrier layer 12. In Fig. 3, the substrate 1 to the barrier layer 12 are depicted as the base 10. Furthermore, a lid 30 is joined via a metal eutectic layer 20. In a preferred example, the interlayer insulating layer 6 is an SiO2 layer. In this first embodiment, a high temperature oxide layer (HTO) formed using a high temperature CVD method is used. The interlayer insulating layer 6 may also be a SiN layer. Since the surface insulating layer 8 is the upper layer of the wiring layer 7, an insulating film that can be formed at a relatively low temperature is preferred. In this first embodiment, a P-TEOS (Tetra Eth Oxy Silane) film is used using a plasma CVD (Chemical Vapor Deposition) apparatus.

[0024] The wiring layer 7 is formed of multiple layers, for example, a four-layer structure in which Ti, TiN, AlCu, and TiN are stacked in this order from the bottom. The respective thicknesses are 60 nm for Ti, 100 nm for TiN, 600 nm for AlCu, and 100 nm for TiN. AlCu is mainly composed of Al, and the Cu content is 0.1 to 1.0%. The wiring layer 7 may be made of any metal layer as long as it has good conductivity. The barrier layer 12 has a two-layer structure of Ti and TiN, and is selectively provided in the area overlapping with the metal eutectic layer 20. The Ti of the barrier layer 12 is 60 nm, and the TiN is 100 nm. The Ti layer serves to improve adhesion to the surface insulating layer 8, and the TiN layer serves to prevent Al from diffusing from AlCu. The barrier layer 12 may be any other metal film such as TaN, W, or TiW as long as it has the effect of preventing Al diffusion. If adhesion to the surface insulating layer 8 is good, the Ti layer can be omitted.

[0025] The metal eutectic layer 20 is a eutectic layer formed by heating and pressurizing the first bonding portion 15 and the second bonding portion 16 shown in FIG. 5 . Eutectic generally refers to an alloy formed by solidifying a liquid phase mixture of two or more metals. Specifically, the laminate consisting of the base 10 and the lid 30 is heated above the eutectic temperature of the two metals contained in the first bonding portion 15 and the second bonding portion 16, bringing the two metals into a liquid phase, and then weight is applied. The laminate is then cooled and returned to a solid phase, thereby bonding the two metals together. In a preferred embodiment, the laminate is placed on a heating jig stage with the base 10 facing downward. Once the laminate reaches a predetermined temperature, a load is applied from the lid 30 side using a weighting jig for a predetermined period of time. The weighting jig is also heated during this process. Once the two metals form a eutectic layer, the weight is removed and the laminate is cooled. In this embodiment, the metal eutectic layer 20 includes a first metal in the first bonding portion 15 and a second metal in the second bonding portion 16, where the first metal is Al and the second metal is Ge. The eutectic temperature of the AlGe eutectic alloy, which is a eutectic of Al and Ge, is approximately 420°C.

[0026] As shown in FIG. 5, before the metal eutectic layer 20 is formed, the base 10 is provided with a first bonding portion 15, and the lid 30 is provided with a second bonding portion 16. The first bonding portion 15 has a two-layer structure consisting of a barrier layer 12 and a first metal layer 13. The barrier layer 12 has a two-layer structure of Ti and TiN, and the first metal layer 13 is an AlCu layer containing Al as its main component. The second bonding portion 16 is made of a single layer of the second metal layer, which is a Ge layer. However, the Cu in the AlCu layer is mixed in for the purpose of preventing electromigration, and its content is low. In this embodiment, the Cu content in AlCu is set to 0.1 to 1.0%. On the other hand, the main component of the second bonding portion 16, which is made of the second metal layer, is Ge. In other words, the main component of the first bonding portion 15 is aluminum, the main component of the second bonding portion 16 is germanium, and the metal eutectic layer 20 formed therefrom contains aluminum and germanium.

[0027] The metal eutectic layer 20 shown in FIG. 3 is a faithful tracing of a micrograph of the eutectic layer. 3, the elemental analysis revealed that the metal eutectic layer 20 is formed with a first region 21 containing Al as a main component as a first metal adjacent to a second region 22 containing Ge as a main component as a second metal. The content of the first metal in the first region 21 is higher than that in the second region 22. The content of the second metal in the second region 22 is higher than that in the first region 21. The second region 22 extends widely along the lid 30, with a portion of it reaching the boundary with the base 10. For example, in FIG. 3, the extensions 22a and 22b reach the base 10. However, the diffusion of the extensions 22a and 22b is stopped by the barrier layer 12 because the barrier layer 12 has the function of preventing the diffusion of Al. The boundary between the first region 21 and the second region 22 is complex and intricate, with many intrusions and extrusions. Furthermore, the extension portion of the second region 22 is greater in the second region 22 than in the first region 21.

[0028] The distribution of Ge in the metal eutectic layer 20 is not uniform, with a relatively large amount present in the second region 22, which is uniform and has no concentration gradient within that region. However, Ge is also present uniformly, albeit in small amounts, within the first region 21. The first region 21 and the second region 22 are in contact with each other without any gaps, and the contact area is larger than the plane area of ​​the bonding region 25. In other words, the first region 21 and the second region 22 are randomly fitted together, resulting in very high bonding strength. In other words, the contact area between the first region 21 and the second region 22 is larger than the area of ​​the bonding region 25 where the base 10 and the lid 30 are bonded by the metal eutectic layer 20.

[0029] It is generally known that Ge has a diamond structure and Al has a face-centered cubic lattice structure, and if there is a large amount of Ge as the main component of the eutectic layer, a solid solution with a diamond structure will be formed, and if there is a large amount of Al, a solid solution with a face-centered cubic lattice structure will be formed. A solid solution is a state in which two elements are dissolved together to form a solid phase with a relatively uniform concentration. However, each solid solution has a different component ratio within the range of the solid solubility limit. That is, the second region 22 containing a large amount of Ge forms a solid solution with a diamond structure, while the first region 21 containing a large amount of Al forms a solid solution with a face-centered cubic lattice structure. Surface energy is a measure when cutting a crystal to extract its surface, and it is known that when comparing the surface energy per unit area of ​​Ge and Al, Ge has a higher surface energy in any plane orientation. In other words, the metal eutectic layer 20 has a plurality of adjacent first regions 21 each having a face-centered cubic lattice structure and a first metal as the main component, and a second region 22 each having a diamond structure and a second metal as the main component.

[0030] As shown in FIG. 3 , a portion of the second region 22 reaches the boundary with the base 10. The second region 22 extends from the lid 30 to the base 10. In other words, the second region 22 reaches the boundary with the base 10. That is, the second region 22 reaches the base 10 regardless of the distance from the lid 30. At the same time, the Ge-rich second region 22 contains Al within a range that does not exceed the solid solubility limit for Ge. The Ge to Al component ratio in the second region 22 is relatively uniform and does not depend on the distance from the lid 30. From the viewpoint of surface energy, the bonding strength is higher when the Ge-rich second region 22 reaches the boundary with the base 10. It is more preferable that the Ge-rich second region 22 extends from the lid 30 to the base 10 in a larger area. 3, at the boundary between the lid body 30 and the metal eutectic layer 20, the second bonding portion 16 made of Ge is formed directly on the lid body 30 (FIG. 5), and therefore Ge diffuses into the silicon that is the lid body 30. That is, the second region 22, which is mainly made of Ge, forms a fine uneven shape at the boundary with the lid body 30 (dotted line in FIG. 3), increasing the contact area and the bonding strength.

[0031] ***Recess and insulating layer*** As shown in FIG. 3, the metal eutectic layer 20 is provided in the recess . The recess 34 is a rectangular groove provided on the inner surface 30b of the lid 30, and has a bottom surface 38 as the bottom portion and side walls 39 on both ends of the bottom surface 38. The bottom surface 38 corresponds to the second surface. In other words, the recess 34 has the bottom surface 38 as the second surface and the side walls 39 connecting the inner surface 30b as the first surface and the bottom surface 38 as the second surface.

[0032] An insulating layer 40 is formed on one side wall 39 of the recess 34. The insulating layer 40 corresponds to the insulating layer in the claims. The insulating layer 40 has a crank-like cross section along the recess 34 and is composed of a first portion 31 provided on the inner surface 30b, a second portion 32 provided on the side wall 39, and a third portion 33 provided on the bottom surface 38. An insulating layer 40 with the same configuration is also formed on the other side wall 39. The two insulating layers 40 are provided symmetrically on both sides of the metal eutectic layer 20. In FIG. 3, the first portion 31 of the insulating layer 40 is in physical contact with the surface insulating layer 8 on the base 10 side. In other words, the insulating layer 40 has a first portion 31 provided on the inner surface 30b as the first surface, a second portion 32 provided on the sidewall 39, and a third portion 33 provided on the bottom surface 38 as the second surface. The insulating layer 40 is provided with the bonding region 25 sandwiched between them.

[0033] In a preferred example, the material of the insulating layer 40 is a SiO2 film. However, the material is not limited to a SiO2 film, and any chemically stable insulating material may be used, such as a SiN film, a B2O3 film, or a Bi2O3 film. In other words, the insulating layer 40 is any one of a silicon oxide layer, a silicon nitride layer, a boron oxide layer, and a bismuth oxide layer.

[0034] When the metal eutectic layer 20 is formed, the Al of the first bonding portion 15 and the Ge of the second bonding portion 16 are heat-treated in the recess 34. The eutectic layer of Al and Ge changes to a liquid phase at the eutectic point, which may cause it to spread or scatter, but the insulating layer 40 formed on both sides of the recess 34 can prevent this. More specifically, since the insulating layer 40 is made of a chemically stable material such as an SiO2 film, eutectic formation with AlGe does not progress, and it functions as a stopper layer. Therefore, the liquid phase eutectic layer 20 can be prevented from scattering onto the functional element 80 during the formation of the metal eutectic layer 20, and the base 10 and the lid 30 can be reliably bonded by the metal eutectic layer 20 in the bonding region 25 within the recess 34.

[0035] ***Differences depending on whether or not there is an intersection with the wiring layer*** 4 is an enlarged view of portion d in FIG. 2, showing a cross section of a portion where there is no underlying wiring layer 7. As shown in FIG. 4, in the portion where there is no underlying wiring layer 7, the height of the surface insulating layer 8 on the base 10 side is lower by the thickness of the wiring layer 7 than in the portion where there is the wiring layer 7. For this reason, the first portion 31 of the insulating layer 40 and the surface insulating layer 8 of the base 10 are not in physical contact with each other, and a gap may occur between them. However, because the gap is narrow by design, the liquid eutectic layer does not splash out of the recess 34. On the other hand, the volume of the recess 34 where there is no wiring layer 7 below in FIG. 4 is larger than the volume of the recess 34 where there is a wiring layer 7 in FIG.

[0036] Here, if the thickness of the metal eutectic layer 20 in the recess 34 where the wiring layer 7 is present in FIG. 3 is defined as height t1 and the width is defined as width w1, and the thickness of the metal eutectic layer 20 in the recess 34 where the wiring layer 7 is not present in FIG. 4 is defined as height t2 and the width is defined as width w2, then t1<t2およびw1> This is because the width of the liquid phase eutectic layer during the formation of the metal eutectic layer 20 is automatically adjusted to an optimum width depending on the distance between the bottom surface 38 of the recess 34 and the surface insulating layer 8 on the base 10 side. As a result, the width of the metal eutectic layer 20 in the plan view of FIG. 1 is a wide width w1 only at the portions intersecting with the wirings 81 to 84, and the remaining portions have a width w2. In other words, the width of the metal eutectic layer 20 is wider in the portion overlapping the wiring than in other portions, and the height of the metal eutectic layer 20 is lower in the portion overlapping the wiring than in other portions.

[0037] Return to Figure 3. In one example, the width of the recess 34 is 90 to 100 μm, and the depth of the recess 34 is 0.1 to 0.5 μm. In this case, the width of the metal eutectic layer 20 is 60 μm or less. Note that this is just an example, and the width may be set appropriately depending on the size and specifications of the device.

[0038] FIG. 6 is a perspective view of the main part showing the electrical wiring structure of the metal eutectic layer, and is an enlarged perspective view of the periphery of the terminal 94 in FIG. 6, the metal eutectic layer 20 is electrically connected to the terminal 94, which is a GND terminal, by the protrusion 15b of the first joint 15 (FIG. 5). The protrusion 15b is a wiring pattern formed together with the first joint 15, and protrudes from the joint region 25 toward the terminal 94. The protrusion 15b does not have an opposing portion on the second joint 16 (FIG. 5) side, and therefore functions as an electrical wiring drawn out from the metal eutectic layer 20.

[0039] The protrusion 15b is provided so as to overlap with the wiring 84 connected to the terminal 94 via the surface insulating layer 8. A conductive contact portion 18 is provided in the portion of the surface insulating layer 8 where the wiring 84 and the protrusion 15b overlap. As a result, the terminal 94 and the metal eutectic layer 20 are electrically connected via the wiring 84, the contact portion 18, and the protrusion 15b. Note that the potential is not limited to the GND potential, and any electrically stable potential may be used, such as a constant potential including the power supply potential. In other words, the lid 30 is electrically connected to any one of the multiple electrical wirings provided on the base 10 via the metal eutectic layer 20.

[0040] ***Lid manufacturing method*** Fig. 7 is a flow chart showing the flow of the method for manufacturing the lid. Figs. 8 to 16 are cross-sectional views of the main part showing one aspect of the manufacturing process. Here, a method for manufacturing the lid 30 having the recess 34 including the insulating layer 40 will be described mainly with reference to FIG. 7 and with reference to other figures as appropriate.

[0041] In step S10, a silicon substrate 30s is prepared, and oxide films are formed on both surfaces of the silicon substrate 30s. This state is shown in FIG. 8, where the oxide film 64 on the inner surface 30b side is formed thicker than the oxide film 63 on the outer surface 30a side. More specifically, after oxide films are formed on both surfaces by thermal oxidation, a P-TEOS film is laminated on the inner surface 30b using a plasma CVD apparatus to thicken the oxide film 64, resulting in asymmetric film thicknesses on the front and back. Note that in FIGS. 8 to 16, the inner surface 30b side of the lid 30 is shown at the top of the drawings.

[0042] In step S11, the outer surface 30a of the silicon substrate 30s is patterned by photolithography to selectively remove the oxide film 63 from areas such as where the sealing holes will be formed. The silicon is then etched by anisotropic etching. This state is shown in FIG. Note that in the following description, "patterning" refers to the use of photolithography.

[0043] In step S12, the oxide films 63 and 64 on both sides of the silicon substrate 30s are removed, and then oxidation is performed again on both sides to form oxide films 66 and 67, as shown in Fig. 10. In a preferred example, wet oxidation is performed to ensure a thermal oxide film thick enough to withstand the subsequent Bosch process.

[0044] In step S13, recesses 34 are formed on the inner surface 30b of the silicon substrate 30s. More specifically, the oxide film 67 is patterned where the recesses 34 are to be formed, and the oxide film 67 and the silicon surface are etched to form the recesses 34. Subsequently, a P-TEOS film is deposited using a plasma CVD apparatus, and then patterned to selectively form an insulating layer 40 around the sidewalls of the recesses 34. This state is shown in FIG.

[0045] In step S14, a Ge film is formed by sputtering on the entire surface of the inner surface 30b of the silicon substrate 30s, and then patterned to form the second bonding portion 16 in the recess 34. This state is shown in FIG. 12. In a preferred example, a protective film 68 made of a P-TEOS film is formed on the entire surface of the inner surface 30b, including the second bonding portion 16. The protective film 68 protects the second bonding portion 16 in the subsequent cavity formation process.

[0046] In step S15, openings 36a, which serve as starting points of sealing holes, are formed in the oxide film 67 on the inner surface 30b side. More specifically, as shown in Fig. 13, the openings 36a are formed in the oxide film 67 using a stepper exposure machine. Then, as shown in Fig. 13, resist 96 is formed in the remaining portions including the recesses 34 and the stopper portions 29 (Fig. 5).

[0047] In step S16, a primary deep drilling process is performed on the inner surface 30b side by the Bosch process. This state is shown in Figure 14, where the sealing hole 36b is drilled from the opening 36a to the primary depth. In addition, the oxide film 67 is thinned.

[0048] In step S17, the lid recess 35, which is the cavity of the lid 30, is formed. First, as shown in FIG. 15, the oxide film 67 on the inner surface 30b side is removed to expose the surface of the silicon substrate 30s in the portion that will become the cavity. Next, a secondary deep trenching process is performed using the Bosch process. This state is shown in FIG. 16, in which the lid recess 35 is formed and the sealing hole 36 is penetrated. At this time, the protective film 68 remains on the surface of the second bonding portion 16.

[0049] In step S18, all of the oxide film is removed by wet etching using BHF (Buffered Hydrogen Fluoride), thereby forming the lid 30 shown in FIG.

[0050] As described above, the transducer 100 of this embodiment can provide the following effects. The transducer 100 includes a base 10 as a first substrate, a lid 30 as a second substrate, a functional element 80 provided between the base 10 and the lid 30, and a metal eutectic layer 20 that bonds the base 10 and the lid 30 in a bonding region 25 located around the functional element 80. A recess 34 is provided on an inner surface 30b of the lid 30 as a first surface facing the base 10. The recess 34 has a bottom surface 38 as a second surface and a sidewall 39 connecting the inner surface 30b (first surface) and the bottom surface 38 (second surface). The transducer 100 includes an insulating layer 40 having a first portion 31 provided on the inner surface 30b (first surface), a second portion 32 provided on the sidewall 39, and a third portion 33 provided on the bottom surface 38 (second surface), and the insulating layer 40 is provided on both sides of the bonding region 25.

[0051] This allows the base 10 and the lid 30 to be reliably bonded by the metal eutectic layer 20 in the bonding region 25. Specifically, when the metal eutectic layer 20 is formed, the Al of the first bonding portion 15 and the Ge of the second bonding portion 16 are heated in the recess 34. The eutectic layer of Al and Ge changes to a liquid phase at the eutectic point, which may cause the layer to spread or scatter. However, the insulating layer 40 formed on both sides of the recess 34 prevents this. This is because the insulating layer 40 is made of a chemically stable material, such as SiO2, and therefore does not undergo eutectic formation with AlGe, acting as a stopper layer. Therefore, the liquid eutectic layer 20 can be prevented from scattering onto the functional element 80 during the formation of the metal eutectic layer 20, and the base 10 and the lid 30 can be reliably bonded by the metal eutectic layer 20 in the bonding region 25 in the recess 34. Therefore, bonding can be performed reliably within the bonding region 25, and a highly reliable transducer 100 can be provided.

[0052] The metal eutectic layer 20 contains aluminum and germanium, and the insulating layer 40 is any one of a silicon oxide layer, a silicon nitride layer, a boron oxide layer, and a bismuth oxide layer. According to this, since the insulating layer 40 is made of a chemically stable material, eutectic formation does not progress between the insulating layer 40 and AlGe, and the insulating layer 40 can function as a stopper layer.

[0053] Furthermore, the width of the metal eutectic layer 20 is wider in the portion overlapping the wiring than in other portions. According to this, when the metal eutectic layer 20 is formed, the liquid phase eutectic layer naturally expands and is adjusted to an optimal width according to the distance between the bottom surface 38 of the recess 34 and the surface insulating layer 8 on the base 10 side, thereby ensuring reliable bonding of the base 10 and the lid 30.

[0054] Furthermore, the height of the metal eutectic layer 20 is lower in the portion overlapping the wiring than in other portions. According to this, when the metal eutectic layer 20 is formed, the liquid phase eutectic layer naturally spreads and is adjusted to an optimal height according to the distance between the bottom surface 38 of the recess 34 and the surface insulating layer 8 on the base 10 side, thereby ensuring reliable bonding of the base 10 and the lid 30.

[0055] Embodiment 2 ***Different aspects of the bonding area*** Fig. 17 is a cross-sectional view of a bonding region according to one aspect of embodiment 2, corresponding to Fig. 3. Fig. 18 is a cross-sectional view of a bonding region according to a different aspect, corresponding to Fig. 4. In the above embodiment, the second bonding portion 16 is described as being formed directly on the lid body 30, but this is not limited thereto, and a barrier layer 17 may be provided as a base. Hereinafter, the same parts as in the above embodiment will be assigned the same numbers, and duplicated explanations will be omitted.

[0056] In this embodiment, a barrier layer 17 is provided between the lid 30 and the second bonding portion 16 (FIG. 5). Other than this, the configuration is the same as that of the above embodiment. The barrier layer 17, like the barrier layer 12, has a two-layer structure of Ti and TiN, and is selectively provided in a portion overlapping the metal eutectic layer 20. The barrier layer 17 is stacked in this order of Ti and TiN from the lid 30 side.

[0057] 17 shows a cross section of the portion where the metal eutectic layer 20 overlaps with the underlying wiring 82. Therefore, similar to FIG. 3, the first portion 31 of the insulating layer 40 is in physical contact with the surface insulating layer 8 on the base 10 side. On the other hand, in FIG. 18, similar to FIG. 4, the first portion 31 of the insulating layer 40 is not in physical contact with the surface insulating layer 8 on the base 10 side. 17, the metal eutectic layer 20 is formed such that a first region 21 containing Al as a primary component and a second region 22 containing Ge as a primary component are adjacent to each other. The second region 22 extends widely along the lid 30, with a portion of it reaching the boundary with the base 10. In other words, as in the description of FIG. 3, the metal eutectic layer 20 achieves a bond with high bonding strength.

[0058] FIG. 19 is a comparative table of contact resistance depending on whether or not a barrier layer is present. Furthermore, providing the barrier layer 17 prevents Ge from diffusing into the lid 30 and improves electrical contact with the silicon that constitutes the lid 30. In other words, the barrier layer 17 enables ohmic contact between the metal eutectic layer 20 and the lid 30. Table 95 in FIG. 19 shows the results of an experiment conducted by the inventors. When the second bonding portion 16 is formed directly on the lid 30, as in Comparative Example 1 in Table 95, ohmic contact is achieved between Si and Ge, but the contact resistance is relatively high at approximately 38.4 MΩ. Note that the contact resistance is the resistance at one contact of the same size. In contrast, as shown in the examples in Table 95, when a Ti / TiN barrier layer 17 was provided, ohmic contact was achieved and the contact resistance was a small value of approximately 1.9 kΩ. This result shows that better electrical conduction can be achieved by providing a Ti / TiN barrier layer 17 between the lid 30 and the metal eutectic layer 20. The same applies to the portion of FIG. 18 where there is no wiring below the metal eutectic layer 20.

[0059] On the other hand, as shown in Comparative Example 2 in Table 95, when one barrier layer 17 made of TiN was provided, ohmic contact was not achieved and the contact resistance value was larger than that of Comparative Example 1. In the above, pure Ge containing no impurities is used for the Ge of the second junction 16, but according to the results of experiments conducted by the inventors, it has been confirmed that when a Ti / TiN barrier layer 17 is provided, even if P-type Ge containing impurities such as Ga is used instead of pure Ge, an ohmic contact is achieved and the contact resistance value is a small value of approximately 62.3 kΩ. Therefore, it is also possible to select to use P-type Ge for the second junction 16.

[0060] As described above, according to the transducer 100 of this embodiment, in addition to the effects of the above embodiment, the following effects can be obtained. The transducer 100 includes a barrier layer 17 of Ti / TiN between the lid 30 and the metal eutectic layer 20 . Therefore, the potential can be supplied to the lid body satisfactorily. Therefore, bonding can be performed reliably within the bonding region 25, and a more reliable transducer 100 can be provided.

[0061] Embodiment 3 ***Application to Inertial Measurement Units*** FIG. 20 is a plan view of a transducer according to the third embodiment, and corresponds to FIG. In the above embodiment, the transducer 100 is described as housing one functional element 80, but this is not limited thereto and the transducer 100 may house multiple functional elements. Hereinafter, the same parts as those in the above embodiment will be assigned the same numbers, and duplicated descriptions will be omitted.

[0062] As shown in FIG. 20, the transducer 110 of this embodiment includes functional elements 85 and 86 in addition to the functional element 80 described above. Functional element 85 is a capacitance change type acceleration sensor that detects acceleration in the X direction. Functional element 86 is a capacitance change type acceleration sensor that detects acceleration in the Y direction. In other words, transducer 110 is a three-axis acceleration sensor that can detect acceleration in three axes: the X, Y, and Z directions. As in FIG. 1, base 10 is substantially rectangular and has a protruding portion 11 that protrudes from cover 30 on the long side in the negative X direction. Protruding portion 11 is provided with multiple terminals for external connection. Like the transducer 100, the transducer 110 has a configuration in which a base 10 and a lid 30 are bonded together in a bonding region 25 with a metal eutectic layer 20, and a recess 34 is provided in the lid 30. The bonding region 25 is formed in a planar manner within the recess 34. The area inside the bonding region 25 is a storage space S.

[0063] Three functional elements 80, 85, and 86 are stored in the storage space S in a state in which they can swing for detection. In Fig. 20, the bonding area 25 is a rectangular ring-shaped area that is slightly smaller than the outer periphery of the lid 30, but this is not limited to this. The bonding area 25 only needs to surround and close the functional elements 80, 85, and 86, and may be polygonal or elliptical. However, the bonding area 25 is configured to intersect with lead wiring (not shown) in a plan view.

[0064] As described above, according to the transducer 110 of this embodiment, in addition to the effects of the above embodiment, the following effects can be obtained. In the transducer 110, similar to the transducer 100, the base 10 and the lid 30 are joined together by a metal eutectic layer 20 in a joining region 25, and the joining region 25 is formed in a planar manner within a recess 34 of the lid 30. Therefore, bonding can be performed reliably within the bonding region 25, and a highly reliable transducer 110 can be provided.

[0065] Fig. 21 is an exploded perspective view of the inertial measurement unit, and Fig. 22 is a perspective view of the board. 21, an inertial measurement unit 2000 of this embodiment is equipped with a transducer 110. The inertial measurement unit 2000 has a rectangular parallelepiped shape that is approximately square in plan view. The inertial measurement unit 2000 is an inertial measurement sensor unit (IMU) that detects the posture and behavior of an object to which it is attached, such as an automobile, a robot, etc. The inertial measurement unit 2000 functions as a so-called six-axis motion sensor that includes a three-axis acceleration sensor and an angular velocity sensor around three axes.

[0066] The inertial measurement unit 2000 includes an outer case 301, a joint member 310, and a sensor module 325 in which the transducer 110 is mounted. The external shape of outer case 301 is a rectangular parallelepiped with a substantially square planar shape, similar to the overall shape of inertial measurement unit 2000, and screw holes 302 are formed near each of two vertices located diagonally across the square. Two screws can be inserted into these two screw holes 302 to secure inertial measurement unit 2000 to the mounting surface of an object such as an automobile.

[0067] Further, outer case 301 is box-shaped and houses sensor module 325 inside. Specifically, sensor module 325 is inserted into outer case 301 with joining member 310 interposed therebetween.

[0068] The sensor module 325 includes an inner case 320 and a substrate 315 . Inner case 320 is a member that supports substrate 315, and substrate 315 is bonded to the bottom surface of inner case 320 via an adhesive.

[0069] Furthermore, inner case 320 is shaped to fit inside outer case 301. Inner case 320 is formed with inner case recess 331 for preventing contact with substrate 315 and opening 321 for exposing connector 316 (described later). Inner case 320 is joined to outer case 301 via joining member 310.

[0070] Next, the substrate 315 on which the transducer 110 is mounted will be described. 22, transducer 110, connector 316, angular velocity sensor 317z that detects angular velocity around the Z axis, and the like are mounted on the surface of substrate 315 that faces inner case 320, which is the top surface. Angular velocity sensor 317x that detects angular velocity around the X axis and angular velocity sensor 317y that detects angular velocity around the Y axis are mounted on the side surface of substrate 315. Note that transducer 100 may be mounted instead of transducer 110.

[0071] Furthermore, a control IC 319 serving as a control unit is mounted on the underside of substrate 315, which faces outer case 301. Control IC 319 is an MCU (Micro Controller Unit) that incorporates a storage unit including nonvolatile memory, an A / D converter, and the like, and controls each unit of inertial measurement unit 2000. The storage unit stores programs that define the order and content for detecting acceleration and angular velocity, a program that digitizes the detected data and incorporates it into packet data, and associated data. Note that multiple other electronic components are also mounted on substrate 315.

[0072] According to such an inertial measurement unit 2000, since the transducer 110 is used, it is possible to provide an inertial measurement unit 2000 that enjoys the effects of the above embodiment and has excellent long-term reliability.

[0073] Embodiment 4 ***Application to timing devices*** Fig. 23 is a perspective view of a transducer according to embodiment 4. Fig. 24 is a plan view of a main part showing the configuration of the transducer. Fig. 25 is a side cross-sectional view taken along line dd in Fig. 24. In the above embodiment, the transducers 100 and 110 have been described, but the present invention is not limited to this and may be applied to timing devices such as vibrators and oscillators as transducers. Hereinafter, the same parts as in the above embodiment will be assigned the same numbers, and duplicated explanations will be omitted.

[0074] The transducer 120 of this embodiment shown in Fig. 23 is an oscillator. The transducer 120 includes a functional element 78. The functional element 78 is a vibration element made of a MEMS device (Fig. 24). 23, the transducer 120 has a flat rectangular parallelepiped shape and is composed of a first substrate 45, a lid 88, etc. In each drawing, the stacking direction of the lid 88 with respect to the first substrate 45 is the Z positive direction. The first substrate 45 is a base substrate made of an SOI substrate. As shown in FIG. 24 , a functional element 78 formed integrally with the first substrate 45 is provided approximately in the center of the substrate. The functional element 78 includes a base 19 supported by the first substrate 45 and a movable portion 14 extending from the base 19. A pair of excitation electrodes (not shown) is formed on the functional element 78. Although FIG. 24 shows three movable portions 14, this is not limitative. As described above, the functional element 78 of this embodiment is a silicon vibration element. Note that the functional element 78 is not limited to a silicon vibration element, and may be a vibration element such as a quartz vibration element or a ceramic vibration element.

[0075] As shown in FIG. 23, the cover 88 has a substantially square shape in plan view, and is composed of a second substrate 46, a circuit layer 47, an interlayer insulating layer 48, an external electrode 49, and the like. The second substrate 46 is made of a silicon substrate, and is provided with a circuit layer 47, an interlayer insulating layer 48, and external electrodes 49 in this order in the positive Z direction. The circuit layer 47 is a circuit layer formed by a semiconductor process on one surface of the second substrate 46, and within this layer is formed an oscillator circuit 59 (FIG. 25) consisting of an integrated circuit including active elements such as transistors and passive elements such as capacitors and resistors. The oscillator circuit 59 is an oscillator circuit that oscillates the functional element 78 to generate an output signal of a predetermined frequency. In this embodiment, the transducer 120 is an oscillator that includes an oscillator circuit, but this is not limited thereto, and the transducer 120 does not necessarily have to include an oscillator circuit. Therefore, the transducer 120 may be a vibrator or other timing device. In a preferred embodiment, the interlayer insulating layer 48 is an SiO2 layer. The external electrodes 49 are rectangular mounting terminals, and a pair of them are provided at diagonal corners of the lid 88. That is, when the transducer 120 is mounted, it is surface-mounted with the lid 88 side facing the mounting surface of a substrate or the like.

[0076] 24, like the transducer 100, the transducer 120 has a configuration in which a first substrate 45 and a second substrate 46 (lid body 88) are bonded together in a bonding region 25 with a metal eutectic layer 20, and a recess 34 is provided in the second substrate 46. The recess 34 is provided in a rectangular ring shape on the periphery of the second substrate 46. The bonding region 25 is formed in the recess 34 in a planar manner. A storage space S is provided inside the bonding region 25.

[0077] As shown in FIG. 25, the storage space S is a space formed by overlapping the cavity of the first substrate 45 and the cavity of the second substrate 46, and the functional element 78 is provided within the storage space S so as to be able to swing. A through electrode 9 is provided between the bonding region 25 and the storage space S. The through electrode 9 is a through electrode provided in a contact hole that penetrates the second substrate 46, and electrically connects the excitation electrode of the functional element 78 and the oscillation circuit 59. In this embodiment, a pair of through electrodes 9 are provided at positions overlapping with the external electrodes 49. One end of the through electrode 9 is electrically connected to the oscillation circuit 59, and the other end is electrically connected to a connection terminal 79 of the second substrate 46. The connection terminal 79 is electrically connected to one excitation electrode of the functional element 78 by a wiring (not shown). Similarly, the other excitation electrode of the functional element 78 is also electrically connected to the oscillation circuit 59 via the corresponding through electrode 9.

[0078] The oscillation circuit 59 and one of the external electrodes 49 are electrically connected by a contact electrode 69. The other external electrode 49 and the oscillation circuit 59 are also electrically connected by a contact electrode 69. The configuration of the recess 34 including the insulating layer 40 and the metal eutectic layer 20 is the same as that described in the above embodiment. Although there are no wirings intersecting the metal eutectic layer 20 in Fig. 24, there may be wirings intersecting the metal eutectic layer 20 as in the above embodiment.

[0079] As described above, according to the transducer 120 of this embodiment, in addition to the effects of the above embodiment, the following effects can be obtained. In the transducer 120, similar to the transducer 100, the first substrate 45 and the second substrate 46 are bonded together by a metal eutectic layer 20 in a bonding region 25, and the bonding region 25 is formed in a planar manner within the recess 34 of the lid 88. Therefore, bonding can be performed reliably within the bonding region 25, and a highly reliable transducer 120 can be provided. [Explanation of symbols]

[0080] 1...substrate, 2...buried insulating layer, 3...semiconductor layer, 5...substrate recess, 6...interlayer insulating layer, 7...wiring layer, 8...surface insulating layer, 9...through electrode, 10...base, 11...extension, 12...barrier layer, 13...first metal layer, 14...movable portion, 15...first bonding portion, 15b...protrusion, 16...second bonding portion, 17...barrier layer, 18...contact portion, 19...base, 20...metal eutectic layer, 21...first region, 22...second region, 22a...extension, 22b...extension, 25...bonding region, 29...stopper portion, 30...lid, 3 0a...outer surface, 30b...inner surface, 30s...silicon substrate, 31...first portion, 32...second portion, 33...third portion, 34...recess, 35...lid recess, 36...sealing hole, 36a...opening, 36b...sealing hole, 37...solder ball, 38...bottom surface, 39...side wall, 40...insulating layer, 45...first substrate, 46...second substrate, 47...circuit layer, 48...interlayer insulating layer, 49...external electrode, 52a...first bar, 52b...second bar, 53...third bar, 54a...first rotation spring, 54b...second rotation spring, 55...movable body, 59...oscillating circuit Path, 60...center line, 61...oscillating axis, 63, 64...oxide film, 65...fixed portion, 67...oxide film, 68...protective film, 71, 71c...movable electrode, 72, 72c...fixed electrode, 73a to 73d...movable electrode group, 74a to 74d...fixed electrode group, 75a to 75d...support portion, 76n...N-type detection portion, 76p...P-type detection portion, 78...functional element, 79...connection terminal, 80...functional element, 81 to 84...wiring, 85...functional element, 86...functional element, 88...lid, 91 to 94...terminal, 95...surface, 96...resist, 100... Transducer, 110...transducer, 120...transducer, 301...outer case, 302...screw hole, 310...jointing member, 315...board, 316...connector, 317x...angular velocity sensor, 317y...angular velocity sensor, 317z...angular velocity sensor, 320...inner case, 321...opening, 325...sensor module, 331...inner case recess, 2000...inertial measurement unit, control IC...319, t1...height, t2...height, w1...width, w2...width.

Claims

1. a first substrate; A second substrate; a functional element provided between the first substrate and the second substrate; a metal eutectic layer that bonds the first substrate and the second substrate together in a bonding region located around the functional element, wherein a recess is provided on a first surface of the second substrate that faces the first substrate, The recess has a second surface that is a bottom portion, and a sidewall connecting the first surface and the second surface, an insulating layer having a first portion provided on the first surface, a second portion provided on the sidewall, and a third portion provided on the second surface; The insulating layers are provided on both sides of the bonding region. Transducer.

2. the metal eutectic layer includes aluminum and germanium; the insulating layer is any one of a silicon oxide layer, a silicon nitride layer, a boron oxide layer, and a bismuth oxide layer; The transducer of claim 1 .

3. a wiring that passes through the bonding region from outside the bonding region and is electrically connected to the functional element, and the width of the metal eutectic layer is wider in a portion that overlaps with the wiring than in other portions; The transducer of claim 2 .

4. the height of the metal eutectic layer is lower in the portion overlapping the wiring than in other portions; The transducer of claim 3 .

Images