Inertial sensor and electronic component

Abstract

An inertial sensor and an electronic component. An inertial sensor or an electronic component is provided with: a base; a cover body; the functional element is arranged between the base body and the cover body; a metal eutectic layer that bonds the base body and the lid body in a bonding region located around the functional element; a plurality of wirings connected to the functional element through the bonding region; and a dummy pattern disposed overlapping the metal eutectic layer at the same height as the wiring in the bonding region.

Description

Technical Field

[0001] The present invention relates to an inertial sensor and an electronic component. Background Art

[0002] Conventionally, a sensor device is known that includes a substrate having a chamber, a sensor element suspended in the chamber, and a lid for sealing the chamber. The substrate and the lid are joined by a joining material. For the joining material, high joining strength and high long-term reliability of sealing have been sought.

[0003] For example, Patent Document 1 discloses using an AlGe eutectic as a joining material. According to this document, the concentration of Ge in the AlGe eutectic is uniform or a function of the distance from the lid or the substrate.

[0004] Prior Art Documents

[0005] Patent Document 1: U.S. Patent Application Publication No. 2010 / 0059835

[0006] However, in the technology of Patent Document 1, the joining strength based on the joining material may decrease. Specifically, if the concentration of Ge decreases according to the distance from the lid, AlGe eutectic formation cannot be achieved on the substrate side, and only an Al layer remains, which may reduce the joining strength. In addition, in the case of eutectic joining, due to the unevenness caused by the lead wires from the sensor element, it is difficult to provide a eutectic joining portion directly above the wire, or the joining material may overflow from the joining area, which may affect the sensor element. That is, there has been a demand for an inertial sensor and an electronic component with high joining strength and excellent reliability between the substrate and the lid. Summary of the Invention

[0007] The inertial sensor according to one aspect of the present application is an electrostatic capacitance change type inertial sensor, and includes: a substrate; a lid; a functional element provided between the substrate and the lid; a metal eutectic layer that joins the substrate and the lid in a joining area surrounding the functional element; a plurality of wirings that pass through the joining area and are connected to the functional element; and dummy patterns provided in the joining area so as to overlap the metal eutectic layer at the same height as the wirings.

[0008] The electronic component according to one aspect of the present application includes: a substrate; a lid; a functional element provided between the substrate and the lid; a metal eutectic layer that joins the substrate and the lid in a joining area surrounding the functional element; a plurality of wirings that pass through the joining area and are connected to the functional element; and dummy patterns provided in the joining area so as to overlap the metal eutectic layer at the same height as the wirings. Brief Description of the Drawings

[0009] Figure 1 It is a top view of the inertial sensor according to Embodiment 1.

[0010] Figure 2 It is along Figure 1 a cross-sectional view of the inertial sensor along the center line of

[0011] Figure 3 It is a main part cross-sectional view of the base body and the cover before joining.

[0012] Figure 4 It is Figure 2 an enlarged view of part b of

[0013] Figure 5 It is Figure 1 a cross-sectional view at the c-c section of

[0014] Figure 6 It is Figure 1 a cross-sectional view at the d-d section of

[0015] Figure 7 It is a cross-sectional view showing the cross-section of Figure 4 in a layer structure.

[0016] Figure 8 It is a top view of the inertial sensor according to Embodiment 2.

[0017] Figure 9 It is Figure 8 a partial enlarged view in the top view of

[0018] Figure 10 It is a main part cross-sectional view of the cover according to Embodiment 3.

[0019] Figure 11 It is an exploded perspective view of the inertial measurement device.

[0020] Figure 12 It is a perspective view of the substrate.

[0021] Reference numeral description

[0022] 1: Substrate; 2: Insulating layer; 3: Semiconductor layer; 5: Recess; 6: Insulating layer; 7: Wiring layer; 8: Insulating layer; 10: Substrate body; 11: Protrusion; 15: First joint portion (first metal layer); 16: Second joint portion (second metal layer); 18: Contact portion; 19: Recess; 20: Metal eutectic layer; 20a: Joint region; 21: First region; 22: Second region; 22a: Extension; 22b: Extension; 25: Recess; 30: Cover; 31: Stopper; 33: Cover; 35: Recess; 40: First dummy pattern; 40c - 40h: First dummy pattern; 41: Second dummy pattern; 41a, 41b: Second dummy pattern; 42 - 49: Terminals; 52a: First rod; 52b: Second rod; 53: Third rod; 54a: First torsion spring; 54b: Second torsion spring; 55: Movable body; 60: Center line; 61: Swing axis; 65: Fixed portion; 71, 71c: Movable electrodes; 72, 72c: Fixed electrodes; 73a - 73d: Groups of movable electrodes; 74a - 74d: Groups of fixed electrodes; 75a: Support portion; 75b: Support portion; 75c: Support portion; 75d: Support portion; 76n: N-type detection portion; 76p: P-type detection portion; 80: Sensor element; 81 - 84: Wiring; 85: Sensor element; 86: Sensor element; 91 - 94: Terminals; 100: Inertial sensor; 110: Inertial sensor; 142: Wiring; 142b: Extension; 142c: Extension; 143: Wiring; 144: Wiring; 144b: Extension; 145: Wiring; 145b: Extension; 145c: Extension; 146 - 149: Wiring; 301: Housing; 302: Threaded hole; 310: Joining component; 315: Substrate; 316: Connector; 317x: Angular velocity sensor; 317y: Angular velocity sensor; 317z: Angular velocity sensor; 320: Inner housing; 321: Opening; 325: Sensor module; 331: Recess; 2000: Inertial measurement device. Detailed implementation manners

[0023] Embodiment 1

[0024] ***Structure of the inertial sensor***

[0025] Figure 1 is a top view of the inertial sensor according to Embodiment 1. Figure 2 is along Figure 1 a cross-sectional view of the inertial sensor along the center line 60.

[0026] Use Figure 1 , Figure 2 to describe the structure of the inertial sensor 100 of this embodiment.

[0027] The inertial sensor 100 is, for example, an acceleration sensor that detects the acceleration in the vertical direction. In addition, in each figure, three mutually perpendicular axes, namely the X-axis, Y-axis, and Z-axis, are illustrated. In the present embodiment, the Z-axis direction is set as the vertical direction, but it is not limited thereto. The direction along the X-axis is referred to as the "X direction", the direction along the Y-axis is referred to as the "Y direction", and the direction along the Z-axis is referred to as the "Z direction". In addition, the end side of the arrow in each axis direction is also referred to as the "positive side", and the base end side of the arrow is referred to as the "negative side". For example, the Y direction refers to the two directions of the positive side and the negative side of the Y direction. In addition, the positive side of the Z direction is also referred to as "up", and the negative side of the Z direction is referred to as "down". In addition, in the following figures, for the sake of easy understanding of the description, the dimensions and scales may sometimes be described differently from the actual ones.

[0028] The inertial sensor 100 is a uniaxial acceleration sensor composed of a MEMS (Micro Electro Mechanical Systems) device. In addition, it is not limited to an acceleration sensor, and as long as it is an electrostatic capacitance change type inertial sensor, it can also be, for example, an angular velocity sensor.

[0029] As Figure 2 shown, the inertial sensor 100 is composed of a base 10, a sensor element 80 disposed on the base 10, a cover 30 covering the sensor element 80, and the like.

[0030] The base 10 is a SOI (Silicon On Insulator) substrate, and is formed by laminating a substrate 1, an insulating layer 2, and a semiconductor layer 3 in the Z direction in sequence. The substrate 1 is a single crystal silicon substrate, and an insulating layer 2 is provided on its upper surface. The insulating layer 2 is a buried insulating layer made of SiO2.

[0031] A recess 5 dug downward from the peripheral portion is provided on the substrate 1. The recess 5 is a chamber and is a part of the accommodation space S for accommodating the sensor element 80. Through the recess 5, the movable body 55 ( Figure 1 ) of the sensor element 80 becomes a structure capable of swinging. In addition, in Figure 2 , an insulating layer 2 is provided on the bottom surface of the recess 5, but the insulating layer 2 may not be provided on the bottom surface of the recess 5.

[0032] The semiconductor layer 3 is, for example, a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), and arsenic (As). In a preferred example, the semiconductor layer 3 and the insulating layer 2 are joined by Si - SiO2 fusion bonding.

[0033] The sensor element 80 is a functional element formed by etching and patterning the semiconductor layer 3. In a preferred example, a deep etching technique based on the Bosch process is used. The sensor element 80 is fixed to the substrate 1 by means of a fixing portion 65 ( Figure 1 ).

[0034] As a preferred example, the cover body 30 uses a silicon substrate. A recess 35 is provided in the cover body 30 and is formed by digging downward from the peripheral portion. The recess 35 is a part of the accommodation space S for accommodating the sensor element 80. A convex portion, i.e., a stopper portion 31, for restricting the excessive swing of the movable body 55 of the sensor element 80 is provided in the recess 35.

[0035] As Figure 2 shown, the base body 10 and the cover body 30 are joined at their peripheral portions by a metal eutectic layer 20. Details of the metal eutectic layer 20 will be described later. In a preferred example, the accommodation space S is filled with an inert gas such as nitrogen, helium, or argon and is hermetically sealed. In addition, in a use temperature environment of about -40°C to 120°C, it is preferably at approximately atmospheric pressure.

[0036] ***Structure of the sensor element***

[0037] As Figure 1 shown, the sensor element 80, which is a functional element, is an acceleration sensor for detecting acceleration in the Z direction and adopts a so-called single-sided seesaw structure in which the movable body 55 swings about a swing axis 61.

[0038] The sensor element 80 is composed of a fixing portion 65, a movable body 55 that can swing about a swing axis 61 passing through the center of the fixing portion 65 and along the Y axis, and first and second torsion springs 54a, 54b, etc. that connect the fixing portion 65 and the movable body 55. The fixing portion 65 is fixed to an unillustrated pedestal portion protruding from the substrate 1 ( Figure 2 ). A recess 5 ( Figure 2 ) is formed around the pedestal portion, and the movable body 55 is configured to be able to swing. In addition, in Figure 1 , a line segment perpendicular to the swing axis 61 and passing through the center of the sensor element 80 along the X axis is defined as the center line 60.

[0039] The movable body 55 has a first rod 52a extending in the positive X direction from the first torsion spring 54a, a second rod 52b extending in the positive X direction from the second torsion spring 54b, and a third rod 53 connecting the first rod 52a and the second rod 52b.

[0040] Four movable electrode groups 73a to 73d in a comb shape are provided on the third rod 53.

[0041] The movable electrode group 73a is composed of six movable electrodes 71c that extend from the third rod 53 in the positive X direction on the negative Y side of the center line 60.

[0042] The movable electrode group 73b is composed of six movable electrodes 71c that extend from the third rod 53 in the negative X direction on the negative Y side of the center line 60. In addition, the number of the movable electrodes 71c is not limited to six, and any number of them can be used as long as it is plural.

[0043] The movable electrode groups 73c and 73d are provided at positions that are line-symmetrical with the movable electrode groups 73a and 73b on the positive Y side with the center line 60 as the axis of symmetry.

[0044] Moreover, on the substrate 1 ( Figure 2 ) side, fixed electrode groups 74a to 74d are provided opposite to the movable electrode groups 73a to 73d.

[0045] The fixed electrode group 74a is composed of a support portion 75a fixed to the substrate 1 and seven fixed electrodes 72 that extend from the support portion 75a in the negative X direction.

[0046] The fixed electrode group 74b is composed of a support portion 75b fixed to the substrate 1 and seven fixed electrodes 72 that extend from the support portion 75b in the positive X direction. In addition, the number is not limited to seven, and any number corresponding to the number of the movable electrodes 71c can be used.

[0047] The fixed electrode groups 74c and 74d are provided at positions that are line-symmetrical with the fixed electrode groups 74a and 74b on the positive Y side with the center line 60 as the axis of symmetry.

[0048] The detection portions based on the fixed electrode group 74a and the movable electrode group 73a, and the detection portions based on the fixed electrode group 74b and the movable electrode group 73b are collectively referred to as the N-type detection portion 76n.

[0049] In the N-type detection portion 76n, a parallel plate type capacitor is formed by the opposed fixed electrode 72 and movable electrode 71c. This capacitor changes according to the change in the overlapping area with the fixed electrode 72 as the displacement of the movable electrode 71c caused by acceleration.

[0050] Similarly, the detection portions based on the fixed electrode group 74c and the movable electrode group 73c, and the detection portions based on the fixed electrode group 74d and the movable electrode group 73d are collectively referred to as the P-type detection portion 76p. In the P-type detection portion 76p, a parallel plate type capacitor is formed by the opposed fixed electrode 72c and movable electrode 71. This capacitor changes according to the change in the overlapping area with the fixed electrode 72c as the displacement of the movable electrode 71 caused by acceleration.

[0051] The movable electrode 71c of the N-type detection unit 76n is thinner in the Z direction than the movable electrode 71 of the P-type detection unit 76p. Specifically, the movable electrode 71c is stepped and thinned from the same thickness as the third rod 53 at the root in the middle of the extending direction. Thus, at the portion facing the fixed electrode 72, the thickness on the positive Z side of all 12 movable electrodes 71c becomes thinner.

[0052] The fixed electrode 72c of the P-type detection unit 76p is thinner in the Z direction than the fixed electrode 72 of the N-type detection unit 76n. Specifically, the fixed electrode 72c is stepped and thinned from the thickness at the root on the support part 75c, 75d side in the middle of the extending direction. Thus, at the portion facing the movable electrode 71, the thickness on the positive Z side of all 14 fixed electrodes 72c becomes thinner.

[0053] According to such a structure, when an acceleration is generated in the positive Z direction, the overlapping area decreases in the N-type detection unit 76n, and the overlapping area is maintained in the P-type detection unit 76p. In addition, when an acceleration in the negative Z direction is generated, the overlapping area is maintained in the N-type detection unit 76n, and the overlapping area decreases in the P-type detection unit 76p.

[0054] Based on such a correlation, in the sensor element 80, by differentially detecting the change in the overlapping area in the N-type detection unit 76n and the P-type detection unit 76p as a change in electrostatic capacitance, the acceleration in the positive / negative Z direction can be detected.

[0055] ***Structure of the bonding region***

[0056] As Figure 1 shown, the base body 10 is substantially rectangular, and the short side in the negative X direction becomes the protruding portion 11 that protrudes from the short side of the cover body 30. Terminals 91 to 94 for external connection are provided on the protruding portion 11.

[0057] Terminal 91 is a movable electrode terminal and is electrically connected to all the movable electrodes 71, 71c through the wiring 81.

[0058] Terminal 92 is an N-type fixed electrode terminal and is electrically connected to all the fixed electrodes 72 of the N-type detection unit 76n through the wiring 82.

[0059] Terminal 93 is a P-type fixed electrode terminal and is electrically connected to all the fixed electrodes 72c of the P-type detection unit 76p through the wiring 83.

[0060] Terminal 94 is a GND terminal and is electrically connected to the metal eutectic layer 20 through the wiring 84. In addition, the details of the connection method between the terminal 94 and the metal eutectic layer 20 will be described later.

[0061] The base body 10 and the lid body 30 are joined at a four-sided annular joining region 20a surrounding the sensor element 80. The joining region 20a is a four-sided annular region that is one circle smaller than the outer peripheral edge of the lid body 30. A metal eutectic layer 20 is formed in the joining region 20a. Further, the metal eutectic layer 20 is formed to cross the wirings 81 to 83 in a plan view.

[0062] In other words, the capacitance change type inertial sensor 100 includes a base body 10, a lid body 30, a sensor element 80 as a functional element provided between the base body 10 and the lid body 30, and a metal eutectic layer 20 that joins the base body 10 and the lid body 30 around the sensor element 80.

[0063] A first dummy pattern 40 is provided on the lower side of the metal eutectic layer 20. The first dummy pattern 40 is a wiring layer formed by the same process as the wirings 81 to 84 and is provided as a four-sided ring along the joining region 20a.

[0064] The portions of the first dummy pattern 40 through which the wirings 81 to 83 pass in the joining region 20a are disconnected, and the first dummy pattern 40 is electrically insulated from each wiring. The first dummy pattern 40 is formed as an island pattern at the disconnected portions of the wirings. For example, a first dummy pattern 40a that is provided as an island between the wiring 81 and the wiring 82. Similarly, a first dummy pattern 40b that is provided as an island between the wiring 82 and the wiring 83. In other words, the first dummy pattern 40 is insulated from the plurality of wirings 81 to 83, and the first dummy pattern 40 is provided between the plurality of wirings 81 to 83 in a plan view. Further, the plurality of wirings 81 to 83 pass through the joining region 20a and are connected to the sensor element 80. In addition, when not distinguishing the island patterns, the first dummy pattern 40 including the first dummy patterns 40a and 40b is referred to as the first dummy pattern 40.

[0065] Further, a four-sided annular second dummy pattern 41 that is one circle smaller than the first dummy pattern 40 is provided on the inner peripheral side of the first dummy pattern 40. Similar to the first dummy pattern 40, the second dummy pattern 41 is a wiring layer formed by the same process as the wirings 81 to 84, the portions of the second dummy pattern 41 through which the wirings 81 to 83 pass are disconnected, and the second dummy pattern 41 is electrically insulated from each wiring. An island-shaped second dummy pattern 41a is provided between the wiring 81 and the wiring 82, and an island-shaped second dummy pattern 41b is provided between the wiring 82 and the wiring 83. When not distinguishing the island patterns, the second dummy pattern 41 including the second dummy patterns 41a and 41b is referred to as the second dummy pattern 41. In addition, a similar four-sided annular dummy pattern may also be provided on the outer peripheral side of the first dummy pattern 40. In other words, a different nth dummy pattern from the first dummy pattern 40 may be provided on the inner peripheral side, or the outer peripheral side, or both sides of the first dummy pattern 40.

[0066] Figure 3is a main part cross-sectional view of the base body and the cover body before joining, corresponding to Figure 2 Corresponding.

[0067] As Figure 3 shown, before forming the metal eutectic layer 20, a first joint portion 15 is provided on the base body 10, and a second joint portion 16 is provided on the cover body 30.

[0068] The first joint portion 15 is an AlCu layer as the first metal layer. The first joint portion 15 is formed, for example, by patterning after film formation using the DC sputtering method. In addition, the first joint portion 15 is also referred to as the first metal layer 15. Cu in the AlCu layer is mixed to prevent electromigration and has a low content rate. Therefore, the main component of the first joint portion 15 is Al.

[0069] The second joint portion 16 is a Ge layer as the second metal layer. In the present embodiment, the second joint portion 16 made of Ge is directly formed on the silicon substrate constituting the cover body 30. In a preferred example, after forming the Ge layer by DC sputtering, patterning is performed to form the second joint portion 16. The second joint portion 16 is also referred to as the second metal layer 16. In other words, the main component of the first metal layer is Al, and the main component of the second metal layer is Ge.

[0070] The first joint portion 15 and the second joint portion 16 are joined by a heating process and a pressing process. Specifically, the laminate formed by overlapping the base body 10 and the cover body 30 is heated to a temperature above the eutectic temperature of the first metal layer 15 and the second metal layer 16, and then pressing is applied in the heated state, thereby performing eutectic bonding. In addition, the eutectic temperature of AlGe is about 420°C. In a preferred example, the laminate is placed on the workbench of the heating jig with the base body 10 facing downward, and when the laminate reaches a specified temperature, a load is applied from the cover body 30 side using a pressing jig for a specified time. At this time, the pressing jig is also heated. Eutectic generally refers to an alloy formed by solidification of two or more metals from a mixed liquid phase state.

[0071] Figure 4 Is Figure 2 an enlarged view of part b, showing the morphology of the joined metal eutectic layer 20.

[0072] When the first joint portion 15 and the second joint portion 16 are joined, by applying heating and pressing, the joining material softens and melts, and a part of it is flattened and overflows.

[0073] Figure 4This state is shown, and it can be seen that the end of the metal eutectic layer 20 on the sensor element 80 side overflows, but the second dummy pattern 41b serves as a dike, and the overflowed part is received in the recess 19. The recess 19 is a groove-shaped depression formed in the upper insulating layer 8 between the first dummy pattern 40b and the second dummy pattern 41b. The recess 19 is formed in a quadrilateral ring shape between the first dummy pattern 40 and the second dummy pattern 41 in a top view.

[0074] In this way, the second dummy pattern 41b functions as a dike to prevent the overflow of the metal eutectic layer 20 and prevent it from entering the sensor element 80 side.

[0075] Figure 5 is Figure 1 a cross-sectional view taken along the c-c section.

[0076] Figure 5 is a cross-sectional view of the terminal 94 as a GND terminal and its wiring 84, corresponding to Figure 4 corresponding.

[0077] As Figure 1 shown, the terminal 94 is connected to the first dummy pattern 40 through the wiring 84. Moreover, as Figure 5 shown, a contact portion 18 is provided in a part of the insulating layer 8 above the first dummy pattern 40. The contact portion 18 is a contact hole, and a part of the metal eutectic layer 20 is filled in the contact portion 18 as an opening portion during bonding, whereby the first dummy pattern 40 is electrically connected to the metal eutectic layer 20. In other words, a GND potential is applied to the first dummy pattern 40 as the first potential, the first dummy pattern 40 is electrically connected to the metal eutectic layer 20, and the first potential is applied to the cover body 30 via the metal eutectic layer 20.

[0078] Figure 6 is Figure 1 a cross-sectional view taken along the d-d section.

[0079] Figure 6 is a cross-sectional view in the extending direction of the Y direction of the bonding region 20a, and the wiring 82 is observed between the first dummy pattern 40a and the first dummy pattern 40b.

[0080] Here, several depressions are generated in the insulating layer 8 above the wiring 82 between the first dummy pattern 40a and the first dummy pattern 40b, but since the intervals between the wiring 82 and the first dummy patterns 40a, 40b are narrow and the thicknesses of the three are the same, it is generally flat as a whole and becomes a state that does not hinder the formation of the metal eutectic layer 20. In other words, the first dummy pattern 40 as a dummy pattern is disposed to overlap the metal eutectic layer 20 at the same height as the wirings 81 to 84 in the bonding region 20a.

[0081] ***Structure of the metal eutectic layer***

[0082] Figure 7 is shown in a layer structure Figure 4 of a cross-sectional view.

[0083] As Figure 7 shown, an insulating layer 6, a wiring layer 7 including a first dummy pattern 40, an insulating layer 8, a metal eutectic layer 20, and a cover 30 are sequentially stacked on a substrate 10.

[0084] The insulating layer 6 is an interlayer insulating layer, and in a preferred example, it is a SiO2 layer. In addition, the insulating layer 6 may also be a SiN layer.

[0085] The wiring layer 7 is formed of multiple layers. For example, it is configured as a four-layer structure stacked in sequence from the bottom up with Ti, TiN, AlCu, and TiN, or a two-layer structure stacked in sequence with TiN and AiCu. In addition, the first dummy pattern 40, the second dummy pattern 41, and wirings 81 to 84 are also included in the wiring layer 7 and are formed in the same process.

[0086] The insulating layer 8 is an interlayer insulating layer, and in a preferred example, it is a SiO2 layer. In addition, the insulating layer 8 may also be a SiN layer. In other words, in the bonding region 20a, the insulating layer 8 is provided on the multiple wirings 81 to 84 and the first dummy pattern 40 and the second dummy pattern 41.

[0087] Figure 7 The shown metal eutectic layer 20 is obtained by faithfully tracing a micrograph of the eutectic layer.

[0088] As a result of elemental analysis, as Figure 7 shown, the metal eutectic layer 20 is formed with a first region 21 mainly composed of Al as the first metal and a second region 22 mainly composed of Ge as the second metal in an adjacent state. The content rate of the first metal in the first region 21 is higher than that of the first metal in the second region 22. The content rate of the second metal in the second region 22 is higher than that of the second metal in the first region 21.

[0089] The second region 22 extends widely along the cover 30, but a part of it reaches the boundary between the metal eutectic layer 20 and the substrate 10. For example, in Figure 7 it, the extending portions 22a and 22b reach the substrate 10. The boundary between the first region 21 and the second region 22 has many undulations and is intricately entangled with each other. In addition, regarding the part extending from the cover 30 to the substrate 10, the second region 22 is more than the first region 21.

[0090] The distribution of Ge in the metal eutectic layer 20 is not uniform and is present in a relatively large amount within the second region 22, where it is uniform and has no concentration gradient. However, within the first region 21, although in a small amount, Ge is also uniformly present. The first region 21 and the second region 22 are in contact with each other without a gap, and their contact area is larger than the planar area of the bonding region 20a. That is, the first region 21 and the second region 22 are randomly fitted together, and their bonding strength is very high. 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 20a where the base body 10 and the cover body 30 are bonded through the metal eutectic layer 20.

[0091] Generally, it is known that Ge has a diamond structure and Al has a face-centered cubic lattice structure. As the main components of the eutectic layer, if there is more Ge, a solid solution with a diamond structure is formed, and if there is more Al, a solid solution with a face-centered cubic lattice structure is formed. A solid solution refers to a substance in which two elements are fused and the whole becomes a solid phase with a relatively uniform concentration. However, each solid solution has different composition ratios within the solid solubility limit.

[0092] That is, the second region 22 with more Ge realizes a solid solution with a diamond structure, and the first region 21 with more Al realizes a solid solution with a face-centered cubic lattice structure. When cutting the crystal to expose the surface, the target is the surface energy. It is known that when comparing Ge and Al in terms of the surface energy per unit area, Ge is higher in any crystal plane orientation. In other words, the metal eutectic layer 20 has multiple first regions 21 with the first metal as the main component and having a face-centered cubic lattice structure and second regions 22 with the second metal as the main component and having a diamond structure, and the first region 21 and the second region 22 are adjacent.

[0093] As Figure 7 shown, a part of the second region 22 reaches the boundary between the metal eutectic layer 20 and the base body 10. Moreover, the second region 22 extends from the cover body 30 to the base body 10. In other words, the second region 22 reaches the boundary between the metal eutectic layer 20 and the base body 10. That is, the second region 22 reaches the base body 10 regardless of the distance from the cover body 30. At the same time, the second region 22 with more Ge contains Al within the range not exceeding the solid solubility limit with respect to Ge. Moreover, the composition ratio of Ge and Al in the second region 22 is relatively uniform and does not depend on the distance from the cover body 30. From the perspective of surface energy, when the second region 22 with more Ge reaches the boundary between the metal eutectic layer 20 and the base body 10, the bonding strength is high. More preferably, it is better when a relatively large part of the second region 22 with more Ge extends from the cover body 30 to the base body 10.

[0094] On the other hand, at the boundary between the cover body 30 and the metal eutectic layer 20 in Figure 7 , a second bonding portion 16 made of Ge is directly formed on the cover body 30 ( Figure 3), so Ge diffuses into the silicon of the lid 30. That is, the second region 22 mainly composed of Ge forms a fine concavo-convex shape at the boundary portion ( Figure 7 the dashed line in) with the lid 30, the contact area increases, and the bonding strength becomes higher.

[0095] In addition, in the above description, the sensor element 80 is described as an acceleration sensor in the Z direction, but it is not limited thereto. As long as it is an electronic component that requires an airtight environment, for example, it can also be an MEMS device such as an angular velocity sensor, a quartz oscillator, a ceramic oscillation element, or other timing devices.

[0096] As described above, according to the inertial sensor 100 of the present embodiment, the following effects can be obtained.

[0097] The inertial sensor 100 is an electrostatic capacitance change type inertial sensor, and includes: a base body 10; a lid 30; a sensor element 80, which is a functional element and is disposed between the base body 10 and the lid 30; a metal eutectic layer 20 that joins the base body 10 and the lid 30 around the sensor element 80; a plurality of wirings 81 to 83 that pass through the joining region 20a and are connected to the sensor element 80; and a first dummy pattern 40 that is disposed in the joining region 20a to overlap the metal eutectic layer 20 at the same height as the wirings 81 to 83.

[0098] Thus, the metal eutectic layer 20 is formed on the first dummy pattern 40 and the wirings 81 to 83. The first dummy pattern 40 is at the same height as the wirings 81 to 83, so the unevenness caused by the plurality of wirings is alleviated, the height of the joining region 20a becomes substantially constant, and it is easy to form the metal eutectic layer 20. Moreover, the base body 10 and the lid 30 are joined by the metal eutectic layer 20 formed by randomly interlocking the first region 21 composed of a face-centered cubic lattice structure and the second region 22 composed of a diamond structure, so a high bonding strength can be obtained.

[0099] Therefore, an inertial sensor 100 with high bonding strength between the base body 10 and the lid 30 and excellent long-term reliability can be provided.

[0100] In addition, the first dummy pattern 40 is insulated from the plurality of wirings 81 to 83, and the first dummy pattern 40 is disposed between the plurality of wirings 81 to 83 in a top view.

[0101] Thus, while ensuring the necessary electrical connection, the height of the joining region 20a where the metal eutectic layer 20 is formed can be made substantially uniform.

[0102] In addition, in the joining region 20a, an insulating layer 8 is provided on the plurality of wirings 81 to 84, the first dummy pattern 40, and the second dummy pattern 41.

[0103] Accordingly, the insulating layer 8 covers the first dummy pattern 40, the second dummy pattern 41 and the gaps between the wirings to fill the gap portions, so that the unevenness is alleviated and the height of the bonding region 20a can be made more uniform.

[0104] In addition, a n-th dummy pattern different from the first dummy pattern 40 may be provided on the inner peripheral side, the outer peripheral side, or both sides of the first dummy pattern 40.

[0105] Accordingly, for example, when the second dummy pattern 41 is provided on the inner peripheral side of the first dummy pattern 40, the second dummy pattern 41b functions as a dike to prevent the metal eutectic layer 20 from overflowing, and can prevent entry into the sensor element 80 side. Therefore, the desired performance can be obtained without hindering the operation of the sensor element 80, and reliability can be ensured.

[0106] In addition, a GND potential is applied to the first dummy pattern 40 as the first potential, the first dummy pattern 40 is electrically connected to the metal eutectic layer 20, and the first potential is applied to the cover 30 via the metal eutectic layer 20.

[0107] Accordingly, since the cover 30 becomes a power supply potential and is electrically stable, it is not easily affected by noise, the operation of the sensor element 80 can be stabilized, and reliability can be ensured.

[0108] In addition, the metal eutectic layer 20 has a plurality of first regions 21 mainly composed of a first metal and having a face-centered cubic lattice structure, and second regions 22 mainly composed of a second metal and having a diamond structure, and the first regions 21 and the second regions 22 are adjacent to each other.

[0109] Accordingly, the base 10 and the cover 30 are joined by the metal eutectic layer 20 in which the first regions 21 having a face-centered cubic lattice structure and the second regions 22 having a diamond structure are randomly interlocked, so that high joining strength can be obtained. Further, the entire bonding region 20a is AlGe eutecticized, so that the reliability is excellent.

[0110] Therefore, an inertial sensor 100 having high bonding strength between the base 10 and the cover 30 and excellent reliability can be provided.

[0111] In addition, the second region 22 reaches the boundary between the metal eutectic layer 20 and the base 10.

[0112] Accordingly, the second region 22 rich in Ge reaches the boundary between the metal eutectic layer 20 and the base 10, so that the bonding strength in the bonding region 20a becomes high.

[0113] In addition, the second region 22 extends from the cover 30 to the base 10.

[0114] Accordingly, the bonding strength in the bonding region 20a becomes even higher.

[0115] In addition, regarding the portion extending from the lid body 30 to the base body 10, the second region 22 is larger than the first region 21. Thus, the extension of the second region 22 with more Ge is larger, and therefore the bonding strength in the bonding region 20a becomes higher.

[0116] In addition, the contact area between the first region 21 and the second region 22 is larger than the area of the bonding region 20a where the base body 10 and the lid body 30 are bonded through the metal eutectic layer 20.

[0117] Thus, since the first region 21 and the second region 22 are randomly fitted with a large contact area, their bonding strength becomes very high.

[0118] In addition, the first metal is Al and the second metal is Ge.

[0119] Thus, a metal eutectic layer 20 with high bonding strength can be formed.

[0120] Embodiment 2

[0121] ***Different modes of the inertial sensor***

[0122] Figure 8 is a top view of the inertial sensor according to Embodiment 2, corresponding to Figure 1 Corresponding.

[0123] In the above embodiment, the case where the inertial sensor 100 houses one sensor element 80 has been described, but it is not limited thereto, and multiple sensor elements may also be housed. Hereinafter, the same parts as those in the above embodiment are denoted by the same reference numerals, and repeated descriptions are omitted.

[0124] As Figure 8 shown, in addition to the above-described sensor element 80, the inertial sensor 110 of the present embodiment further includes a sensor element 85 and a sensor element 86.

[0125] The sensor element 85 is a capacitance change type acceleration sensor that detects acceleration in the Y direction. The sensor element 86 is a capacitance change type acceleration sensor that detects acceleration in the X direction. That is, the inertial sensor 110 is a three-axis acceleration sensor that can detect accelerations in three axes of the XYZ directions.

[0126] Similar to the inertial sensor 100, the inertial sensor 110 has a structure in which the base body 10 and the lid body 30 are joined in the joining region 20a through the metal eutectic layer 20, and has a storage space S inside. Three sensor elements 80, 85, and 86 are stored in the storage space S in a swingable state.

[0127] External connection terminals 42 to 49 are provided at the protruding portion 11 of the base 10.

[0128] Terminal 42 is a movable electrode terminal and is electrically connected to the movable electrodes of all the sensor elements 80, 85, and 86 through a wiring 142. In addition, illustration of the wiring pattern within the accommodation space S for the wiring 142 is omitted. The same applies to the other wirings 144 to 149.

[0129] Terminal 43 is a GND terminal and is electrically connected to the metal eutectic layer 20 through a wiring 143 and a contact portion 18.

[0130] Terminal 44 is the first fixed electrode terminal of the sensor element 86 and is electrically connected to the first fixed electrode of the sensor element 86 through a wiring 144.

[0131] Terminal 45 is the second fixed electrode terminal of the sensor element 86 and is electrically connected to the second fixed electrode of the sensor element 86 through a wiring 145.

[0132] Terminal 46 is the first fixed electrode terminal of the sensor element 85 and is electrically connected to the first fixed electrode of the sensor element 85 through a wiring 146.

[0133] Terminal 47 is the second fixed electrode terminal of the sensor element 85 and is electrically connected to the second fixed electrode of the sensor element 85 through a wiring 147.

[0134] Terminal 48 is the first fixed electrode terminal of the sensor element 80 and is electrically connected to the first fixed electrode of the sensor element 80 through a wiring 148.

[0135] Terminal 49 is the second fixed electrode terminal of the sensor element 80 and is electrically connected to the second fixed electrode of the sensor element 80 through a wiring 149.

[0136] The first dummy pattern 40 includes the first dummy pattern portions 40c to 40h as a plurality of island-like portions. Similarly, the second dummy pattern 41 includes the second dummy pattern portions 41c to 41g as a plurality of island-like portions. The wirings 144 to 149 pass through between these island-like portions in a crank shape and enter the accommodation space S.

[0137] After extending in the positive X direction, the wiring 142 bends in the positive Y direction, extends along the first dummy pattern 40, and then bends in the positive X direction to enter the accommodation space S. Here, the portion extending along the first dummy pattern 40 can exhibit the same dike effect as the second dummy pattern 41.

[0138] After extending in the positive X direction, the wiring 144 bends in the negative Y direction, extends along the first dummy pattern 40, and then bends in the positive X direction to enter the accommodation space S.

[0139] Similarly, after extending in the positive X direction, wirings 145 to 147 bend in the negative Y direction, and after extending along the first dummy pattern 40, they bend in the positive X direction and enter the storage space S.

[0140] After extending in the positive X direction, wiring 148 bends in the positive Y direction, and after extending along the first dummy pattern 40, it bends in the positive X direction and enters the storage space S.

[0141] After extending in the positive X direction, wiring 149 bends in the negative Y direction, and after extending along the first dummy pattern 40, it bends in the positive X direction and enters the storage space S.

[0142] Thus, each of wirings 142, 144 to 149 has a bent portion bent in a crank shape and an extending portion extending along the first dummy pattern 40, and this extending portion functions as a dike to prevent the metal eutectic layer 20 from overflowing into the storage space S. In other words, wirings 142, 144 to 149 have a bent portion and an extending portion extending along the first dummy pattern 40.

[0143] Figure 9 is Figure 8 a partial enlarged view in the top view, and is an enlarged view of the peripheral portion of the terminal 43.

[0144] As Figure 9 shown, an extension portion 142b branching in the positive Y direction and an extension portion 142c branching in the negative Y direction are provided in the extending portion of wiring 142. Thereby, the extending portion of wiring 142 along the first dummy pattern 40 becomes longer by the amounts of the extension portions 142b and 142c. Similarly, an extension portion 144c branching in the negative Y direction is provided in the extending portion of wiring 144. Thereby, the extending portion of wiring 144 along the first dummy pattern 40 becomes longer by the amount of the extension portion 144c.

[0145] An extension portion 145b branching in the positive Y direction and an extension portion 145c branching in the negative Y direction are provided in the extending portion of wiring 145. Thereby, the extending portion of wiring 145 along the first dummy pattern 40 becomes longer by the amounts of the extension portions 145b and 145c. Although wirings 146 to 149 are not shown in Figure 9 , the extending portions are extended in the same manner as the above-described wirings.

[0146] By adding extension portions to the extending portions of the wirings in this way, a longer dike wiring along the first dummy pattern 40 is formed, and thus it is possible to prevent the metal eutectic layer 20 from overflowing into the storage space S.

[0147] Embodiment 3

[0148] ***Different forms of the lid body***

[0149] Figure 10 is a cross-sectional view of the main part of the lid according to Embodiment 3, corresponding to Figure 3 .

[0150] In the above embodiment, the case where an overflow prevention structure for preventing the metal eutectic layer 20 from overflowing is provided on the base 10 side has been described. However, an overflow prevention structure for preventing the metal eutectic layer 20 from overflowing may also be provided on the lid 30 side. Hereinafter, the same parts as those in the above embodiment are denoted by the same reference numerals, and repeated descriptions are omitted.

[0151] Figure 10 is an enlarged view of the periphery of the bonding area 20a in the lid 33 before bonding. In the lid 33 of the present embodiment, a recess 25 is provided along the bonding area 20a. The recess 25 is a groove with a flat bottom surface. Before bonding, as Figure 10 shown, a second bonding portion 16 is formed in the recess 25.

[0152] When the second bonding portion 16 is bonded to the first bonding portion 15 to form the metal eutectic layer 20, the overflow amount of the metal eutectic layer 20 is absorbed into the recess 25 to function as preventing lateral outflow. In other words, a recess 25 is provided in the lid 33 along the bonding area 20a.

[0153] The lid 33 can be applied in place of the lids 30 of the above-described inertial sensors 100 and 110. By using the lid 33, the dike effect can be further improved.

[0154] Embodiment 4

[0155] ***Application to Inertial Measurement Device***

[0156] Figure 11 is an exploded perspective view of an inertial measurement device. Figure 12 is a perspective view of a substrate.

[0157] In Figure 11 the inertial measurement device 2000 of the present embodiment shown, an inertial sensor 110 is mounted. The inertial measurement device 2000 is a rectangular parallelepiped having a substantially square shape when viewed from above.

[0158] The inertial measurement device 2000 is an inertial measurement sensor unit (IMU: Inertial Measurement Unit) that detects the posture and behavior of an object to be mounted such as an automobile or a robot. The inertial measurement device 2000 functions as a so-called 6-axis motion sensor including a three-axis acceleration sensor and angular velocity sensors around the three axes.

[0159] The inertial measurement device 2000 includes a housing 301, a bonding member 310, and a sensor module 325 on which the inertial sensor 110 is mounted.

[0160] The outer shell 301 has the same overall shape as the inertial measurement device 2000, and is a rectangular parallelepiped with a substantially square top view shape. Threaded holes 302 are formed near two vertices located in the diagonal direction of the square. Two screws can pass through the two threaded holes 302 to fix the inertial measurement device 2000 to the mounting surface of a mounted object such as an automobile.

[0161] In addition, the outer shell 301 is box-shaped, and a sensor module 325 is housed inside it. Specifically, it has a structure in which the joining member 310 is interposed and the sensor module 325 is inserted inside the outer shell 301.

[0162] The sensor module 325 has an inner shell 320 and a substrate 315.

[0163] The inner shell 320 is a member that supports the substrate 315, and the substrate 315 is joined to the lower surface of the inner shell 320 by an adhesive.

[0164] In addition, the inner shell 320 is shaped to be housed inside the outer shell 301. A recess 331 for preventing contact with the substrate 315 and an opening 321 for exposing a connector 316 described later are formed in the inner shell 320. The inner shell 320 is joined to the outer shell 301 by the joining member 310.

[0165] Next, the substrate 315 on which the inertial sensor 110 is mounted will be described.

[0166] As Figure 12 shown, on the upper surface of the substrate 315, that is, the surface on the inner shell 320 side, an inertial sensor 110, a connector 316, an angular velocity sensor 317z for detecting the angular velocity around the Z axis, etc. are mounted. On the side surface of the substrate 315, an angular velocity sensor 317x for detecting the angular velocity around the X axis and an angular velocity sensor 317y for detecting the angular velocity around the Y axis are mounted. In addition, an inertial sensor 100 can be mounted instead of the inertial sensor 110.

[0167] In addition, a control IC 319 as a control unit is mounted on the lower surface of the substrate 315, that is, the surface on the outer shell 301 side. The control IC 319 is an MCU (Micro Controller Unit), and has a storage unit including a non-volatile memory, an A / D converter, etc. inside, and controls each part of the inertial measurement device 2000. Programs that define the sequence and content for detecting acceleration and angular velocity, programs for digitizing the detection data and assembling it into packet data, attached data, etc. are stored in the storage unit. In addition, a plurality of electronic components are mounted on the substrate 315.

[0168] According to such an inertial measurement device 2000, since the inertial sensor 110 is used, it is possible to provide an inertial measurement device 2000 with excellent reliability that enjoys the effects involved in the above-described embodiments.

Claims

1. An inertial sensor, which is an electrostatic capacitance change type inertial sensor, comprising: A substrate; A cover; A functional element disposed between the substrate and the cover; A metal eutectic layer that joins the substrate and the cover in a joining region around the functional element; A plurality of wirings that pass through the joining region and are connected to the functional element; And A dummy pattern that is disposed in the joining region to overlap the metal eutectic layer at the same height as the wirings.

2. The inertial sensor according to claim 1, wherein The dummy pattern is insulated from the plurality of wirings, The dummy pattern is disposed between the plurality of wirings in a top view.

3. The inertial sensor according to claim 2, wherein In the joining region, an insulating layer is provided over the plurality of wirings and the dummy pattern.

4. The inertial sensor according to claim 3, wherein When the dummy pattern is a first dummy pattern, On the inner peripheral side, or the outer peripheral side, or both the inner peripheral side and the outer peripheral side of the first dummy pattern, there is further provided an nth dummy pattern different from the first dummy pattern.

5. The inertial sensor according to claim 3, wherein A first potential is applied to the dummy pattern, The dummy pattern is electrically connected to the metal eutectic layer, The first potential is applied to the cover via the metal eutectic layer.

6. The inertial sensor according to claim 3, wherein The wiring has a bent portion and an extending portion that extends along the dummy pattern.

7. The inertial sensor according to claim 5, wherein A recess is provided in the cover along the joining region.

8. The inertial sensor according to claim 4, wherein The metal eutectic layer has a plurality of first regions mainly composed of a first metal and having a face-centered cubic lattice structure and second regions mainly composed of a second metal and having a diamond structure, and the first regions and the second regions are adjacent to each other.

9. The inertial sensor according to claim 8, wherein The second region reaches the boundary between the metal eutectic layer and the substrate.

10. The inertial sensor according to claim 9, wherein The second region extends from the cover to the substrate.

11. The inertial sensor according to claim 10, wherein Regarding the portion extending from the cover to the substrate, the second region is more than the first region.

12. The inertial sensor according to claim 11, wherein The contact area between the first region and the second region is larger than the area of the joining region where the substrate and the cover are joined by the metal eutectic layer.

13. The inertial sensor according to claim 12, wherein The first metal is Al and the second metal is Ge.

14. An electronic component, comprising: A substrate; A cover; A functional element disposed between the substrate and the cover; A metal eutectic layer that joins the substrate and the cover in a joining region around the functional element; A plurality of wirings that pass through the joining region and are connected to the functional element; And Dummy pattern, which is disposed in the bonding region so as to overlap with the wiring at the same height and the metal eutectic layer.

15. The electronic component according to claim 14, wherein the dummy pattern is insulated from the plurality of wirings, the dummy pattern is disposed between the plurality of wirings in a plan view.

16. The electronic component according to claim 15, wherein in the bonding region, an insulating layer is provided above the plurality of wirings and the dummy pattern.

17. The electronic component according to claim 16, wherein when the dummy pattern is set as the first dummy pattern, a second dummy pattern different from the first dummy pattern is further provided on the inner peripheral side, or the outer peripheral side, or both the inner peripheral side and the outer peripheral side of the first dummy pattern.

18. The electronic component according to claim 16, wherein a first potential is applied to the dummy pattern, the dummy pattern is electrically connected to the metal eutectic layer, the first potential is applied to the cover via the metal eutectic layer.

19. The electronic component according to claim 17, wherein the metal eutectic layer has a plurality of first regions mainly composed of a first metal and having a face-centered cubic lattice structure and second regions mainly composed of a second metal and having a diamond structure, and the first regions and the second regions are adjacent to each other.

20. The electronic component according to claim 19, wherein the second region reaches the boundary between the metal eutectic layer and the substrate.

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