Vibration device

Abstract

To provide a vibration device that is excellent in the reliability of electrical connection.SOLUTION: A vibration device 1 has: a base 10 that has a first surface 10a; a first conductive layer 43 that is arranged on the first surface 10a; a vibration element 25 that is located on a side of the first surface 10a, and includes an element substrate 30 and a second conductive layer 44 located on a surface of the element substrate 30 facing the base 10; a metal bump 41 that is arranged between the base 10 and the vibration element 25, joins the base 10 and the vibration element 25 to each other, and electrically connects the first conductive layer 43 and the second conductive layer 44 to each other; and a resin layer 42 that is arranged between the first conductive layer 43 and the base 10. The first conductive layer 43 includes a first portion 61 that is arranged on the base 10, a second portion 62 to which the metal bump 41 is joined, and an intermediate portion 63 that is located between the first portion 61 and the second portion 62. The resin layer 42 is arranged between the second portion 62 and intermediate portion 63 and the base 10. The angle θ1 between the intermediate portion 63 and the base 10 satisfies θ1<90°.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] For example, Patent Document 1 discloses a vibration device having a base, a vibration element located on the upper surface of the base, a conductive layer disposed on the upper surface, metal bumps disposed between the base and the vibration element and joining the base and the vibration element, and a low elastic modulus layer interposed between the base and the conductive layer and having a lower elastic modulus than the metal bump. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-085834 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the vibration device described in Patent Document 1, the conductive layer is formed so as to cover the resin layer disposed on the base. Therefore, depending on the shape of the resin layer, a corner that is almost perpendicular to the conductive layer is formed in a cross-sectional view. As a result, there is a problem that the conductive layer is disconnected at the corner, and the reliability of the electrical connection is not sufficiently obtained. [Means for solving the problem]

[0005] The vibration device has a base having a first surface and a second surface which are in a front-back relationship, a first conductive layer arranged on the first surface, a vibration element located on the first surface side of the base and including an element substrate and a second conductive layer arranged on the base side surface of the element substrate, metal bumps arranged between the base and the vibration element, bonding the base and the vibration element and electrically connecting the first conductive layer and the second conductive layer, and a resin layer arranged between the first conductive layer and the base, wherein the first conductive layer includes a first portion arranged on the base, a second portion to which the metal bump is bonded, and an intermediate portion located between the first portion and the second portion, and the resin layer is arranged between the second portion and the intermediate portion and the base, and an angle θ1 between the intermediate portion and the base satisfies θ1<90°. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing a schematic structure of a vibration device according to a first embodiment. [Diagram 2] FIG. 1 is a plan view showing a schematic structure of a vibration device according to a first embodiment. [Diagram 3] Cross-sectional view taken along line A1-A1 in Figure 2. [Figure 4] Enlarged view of part B in Figure 3. [Diagram 5] FIG. 11 is an enlarged cross-sectional view showing a schematic structure of a vibration device according to a second embodiment. [Figure 6] FIG. 11 is a plan view showing a schematic structure of a vibration device according to a third embodiment. [Figure 7] Cross-sectional view taken along line A2-A2 in Figure 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] 1. First embodiment First, an oscillator including a vibration element 25 will be taken as an example of the vibration device 1 according to the first embodiment and will be described with reference to FIGS. 1 to 4. FIG. In FIG. 2, for convenience of explanation of the internal configuration of the vibration device 1, the cover 20 is removed. For convenience of explanation, the following perspective views, plan views, and cross-sectional views show three mutually perpendicular axes, the X-axis, the Y-axis, and the Z-axis. The direction along the X-axis is called the "X-direction", the direction along the Y-axis is called the "Y-direction", and the direction along the Z-axis is called the "Z-direction". The arrow side of each axis is also called the "plus side", and the opposite side to the arrow is also called the "minus side". The plus side of the Z direction is also called the "upper", and the minus side of the Z direction is also called the "lower".

[0008] 1, 2, and 3, the vibration device 1 includes a base 10 having a first surface 10a and a second surface 10b in a front-back relationship, a first conductive layer 43 disposed on the first surface 10a, a vibration element 25 located on the first surface 10a side of the base 10 and including an element substrate 30 and a second conductive layer 44 located on the surface of the element substrate 30 on the base 10 side, a metal bump 41 disposed between the base 10 and the vibration element 25, bonding the base 10 and the vibration element 25 and electrically connecting the first conductive layer 43 and the second conductive layer 44, a resin layer 42 disposed between the first conductive layer 43 and the base 10, and a lid 20 bonded to the base 10 and housing the vibration element 25 between the base 10 and the lid 20. The base 10 and the lid 20 constitute a package 2 housing the vibration element 25.

[0009] The base 10 is a semiconductor substrate, in particular a silicon substrate. However, the base 10 is not particularly limited, and may be a substrate made of a semiconductor material other than silicon, such as Ge, GaP, GaAs, or InP.

[0010] The base 10 is a rectangular flat plate in plan view from the Z direction, and has a first surface 10a and a second surface 10b that are in a front-back relationship, a resin layer 42 is disposed on the first surface 10a, and a first conductive layer 43 that becomes the internal terminal 12 is formed so as to cover the resin layer 42. That is, the resin layer 42 is disposed between the base 10 and the first conductive layer 43. In addition, the vibration element 25 is bonded onto the first conductive layer 43 via a metal bump 41.

[0011] An external terminal 13 and a circuit section 50 are formed on the second surface 10b of the base 10. A through electrode (not shown) that penetrates the first surface 10a and the second surface 10b is formed on the base 10, and the through electrode electrically connects the internal terminal 12 and the circuit section 50. The circuit section 50 has an oscillation circuit 51 electrically connected to the vibration element 25. The oscillation circuit 51 oscillates the vibration element 25 to generate a reference signal such as a clock signal, and outputs the reference signal from the external terminal 13.

[0012] The configuration of the first conductive layer 43 is not particularly limited, but for example, in this embodiment, the first conductive layer 43 has a four-layer configuration in which a surface layer made of a laminate of a TiW layer and an Au layer is laminated on a base layer made of a laminate of a TiW layer and a Cu layer. That is, the TiW layer, the Cu layer, the TiW layer, and the Au layer are laminated in this order from the first surface 10a side. With this configuration, the first conductive layer 43 as a whole can be thickened by thickening the Cu layer while keeping the expensive Au layer thin. Therefore, the first conductive layer 43 having a mechanical strength that can sufficiently withstand deformation when an impact is applied can be formed relatively inexpensively. The external terminal 13 provided on the second surface 10b of the base 10 has a similar configuration. The first conductive layer 43 may have a two-layer configuration in which a Ti layer and an Au layer are laminated in this order from the first surface 10a side.

[0013] The resin layer 42 is disposed so as to overlap the pad electrode 34 of the vibration element 25, as described later. The elastic modulus of the resin layer 42 is smaller than that of the metal bump 41. That is, the resin layer 42 is softer than the metal bump 41. The elastic modulus of the resin layer 42 is not particularly limited, but is preferably 1 / 10 or less, more preferably 1 / 50 or less, and even more preferably 1 / 100 or less of that of the metal bump 41. This makes the resin layer 42 sufficiently soft, and the shock is less likely to be transmitted to the vibration element 25 via the metal bump 41 due to the shock mitigation effect, so that sufficient shock resistance can be exhibited.

[0014] The material of the resin layer 42 is not particularly limited, but is preferably a photosensitive resin material such as an ultraviolet-curable type, such as epoxy resin, polyimide resin, or phenolic resin. In particular, in this embodiment, phenolic resin is used. This allows the resin layer 42 to be finely processed, and the resin layer 42 can be formed with high accuracy, and the resonator device 1 can be made smaller. In addition, since the resin layer 42 can be formed using a semiconductor process, the resonator device 1 can be manufactured efficiently. In addition, the resin layer 42 may contain additives such as metal fillers for the purpose of adjusting the linear expansion coefficient, imparting electrical conductivity, or other purposes.

[0015] The lid 20 is a semiconductor substrate, a silicon substrate, like the base 10. This makes the linear expansion coefficients of the base 10 and the lid 20 equal, suppressing the generation of thermal stress caused by thermal expansion, and resulting in a vibration device 1 with excellent vibration characteristics. In addition, since the vibration device 1 can be formed by a semiconductor process, the vibration device 1 can be manufactured with high precision and can be made compact. However, the material of the lid 20 is not particularly limited, and a semiconductor substrate other than silicon, such as a semiconductor substrate of Ge, GaP, GaAs, InP, etc., may be used.

[0016] The lid 20 is rectangular in plan view from the Z direction, has a third surface 20a and a fourth surface 20b that are in a front-back relationship, and has a recess 22 that opens to the base 10 side. The third surface 20a of the lid 20 is directly bonded to the first surface 10a of the base 10, and together with the base 10, forms an accommodation space 23 that accommodates the vibration element 25. The accommodation space 23 is airtight and in a reduced pressure state, preferably closer to a vacuum state. This reduces viscous resistance and improves the vibration characteristics of the vibration element 25. However, the atmosphere of the accommodation space 23 is not particularly limited.

[0017] The direct bonding between the base 10 and the lid 20 may be any type of bonding that does not require an intermediate material between two bonding surfaces made of the same material. The bonding method is not limited to this, and may be a bonding method using glass frit or the like, a metal eutectic bonding method in which metal films formed on the first surface 10a of the base 10 and the third surface 20a of the lid 20 are bonded to each other, or an activation bonding method in which the surface of the first surface 10a of the base 10 and the surface of a metal film such as Au formed on the third surface 20a of the lid 20 are activated by plasma irradiation to bond them.

[0018] The vibration element 25 is located on the first surface 10a side of the base 10, and has an element substrate 30, a first electrode 31a arranged on the base 10 side of the element substrate 30, and a second electrode 31b arranged on the cover body 20 side, which is the opposite side of the base 10 side of the element substrate 30. The first electrode 31a and the second electrode 31b are formed of a second conductive layer 44, and have an excitation electrode 32 that vibrates the element substrate 30, a pad electrode 34 that outputs a vibration signal to the outside and fixes the vibration element 25 to the base 10, and a lead electrode 33 that electrically connects the excitation electrode 32 and the pad electrode 34. The second electrode 31b further has a side electrode 35 that electrically connects the lead electrode 33 formed on the element substrate 30 and the pad electrode 34 formed under the element substrate 30. That is, the vibration element 25 has a second conductive layer 44 that becomes the pad electrode 34 located on the surface of the element substrate 30 on the base 10 side. Moreover, the area of ​​the excitation electrode 32 of the first electrode 31a and the area of ​​the excitation electrode 32 of the second electrode 31b are the same, and are arranged to overlap each other in a plan view from the Z direction.

[0019] The vibration element 25 is disposed on the first surface 10a side of the base 10, and is fixed to the internal terminal 12 formed by the first conductive layer 43 of the base 10 via the metal bump 41 at the portion of the pad electrode 34 formed by the second conductive layer 44. Therefore, the excitation electrode 32 of the vibration element 25 is electrically connected to the oscillation circuit 51 via the metal bump 41 and the internal terminal 12, and the element substrate 30 can be vibrated.

[0020] The configuration of the second conductive layer 44 is not particularly limited, but for example, in this embodiment, the second conductive layer 44 has a two-layer configuration in which a Cr layer is used as a base layer and an Au layer is used as a surface layer. That is, the Cr layer and the Au layer are laminated in this order from the element substrate 30 side. By using the Cr layer as the base layer, it is possible to improve the adhesion between the element substrate 30 and the Au layer.

[0021] The element substrate 30 has a thickness-shear vibration mode, and in this embodiment is made of an AT-cut quartz crystal substrate. The AT-cut quartz crystal substrate has a third-order frequency-temperature characteristic, and therefore the vibration element 25 has excellent temperature characteristics.

[0022] The configuration of the vibration element 25 is not limited to the above configuration. For example, the vibration element 25 may be a mesa type in which the vibration area sandwiched between the excitation electrodes 32 protrudes from its surroundings, or conversely, may be an inverted mesa type in which the vibration area is recessed from its surroundings. In addition, bevel processing for grinding the periphery of the element substrate 30, or convex processing for making the upper and lower surfaces into convex curved surfaces may be performed.

[0023] The vibration element 25 is not limited to one that vibrates in a thickness-shear vibration mode, and may be, for example, a vibration element in which a plurality of vibrating arms vibrate in an in-plane direction. That is, the element substrate 30 is not limited to one formed from an AT-cut quartz substrate, and may be formed from a quartz substrate other than an AT-cut quartz substrate, for example, an X-cut quartz substrate, a Y-cut quartz substrate, a Z-cut quartz substrate, a BT-cut quartz substrate, an SC-cut quartz substrate, an ST-cut quartz substrate, or the like. In the present embodiment, the element substrate 30 is made of quartz, but is not limited thereto, and may be made of a piezoelectric single crystal such as lithium niobate, lithium tantalate, lithium tetraborate, langalite, potassium niobate, or gallium phosphate, or may be made of a piezoelectric single crystal other than these. Furthermore, the vibration element 25 is not limited to a piezoelectric drive type vibration element, and may be an electrostatic drive type vibration element using electrostatic force.

[0024] Next, the structure of the joint between the base 10 and the vibration element 25 will be described with reference to FIG. The first conductive layer 43, which is the internal terminal 12, covers the entire surface of the resin layer 42. Therefore, the gas generated from the resin layer 42 can be trapped within the first conductive layer 43, and the gas can be prevented from being released into the accommodation space 23, and the change or deterioration of the vibration characteristics of the vibration element 25 due to the gas causing contamination of the atmosphere in the accommodation space 23, pressure change, etc. can be prevented. Thus, the vibration device 1 has excellent reliability.

[0025] The first conductive layer 43 includes a first portion 61 disposed on the base 10, a second portion 62 to which the metal bump 41 is bonded, and an intermediate portion 63 located between the first portion 61 and the second portion 62, and the intermediate portion 63 has a curved shape in a cross-sectional view. The angle θ1 between the intermediate portion 63 and the base 10 satisfies θ1<90°. That is, the corner of the resin layer 42 is configured such that the base 10 side is an acute angle and the vibration element 25 side is a curved angle. Therefore, it is possible to suppress disconnection of the first conductive layer 43 at the corner of the resin layer 42. The reason why the intermediate portion 63 has a curved shape is that the corner of the resin layer 42, which was nearly vertical, is transformed into a curved shape by performing an annealing process after the resin layer 42 is patterned using a semiconductor process.

[0026] The side surface 41a of the metal bump 41 on the base 10 side has an outer shape portion 66 that approaches the central axis c1 of the metal bump 41 from the vibration element 25 side toward the base 10 side in a cross-sectional view, and the end portion of the second portion 62 of the first conductive layer 43 on the side of the intermediate portion 63 is joined to the outer shape portion 66. The outer shape portion 66 is an arc shape. This is because, when the base 10 and the vibration element 25 are joined via the metal bump 41, the resin layer 42, which is softer than the metal bump 41, is depressed because the resin layer 42 is pressed from the vibration element 25 side. Therefore, the second portion 62 of the first conductive layer 43 is also depressed toward the base 10 side along the shape of the metal bump 41.

[0027] As described above, in the vibration device 1 of this embodiment, the resin layer 42 is disposed between the second portion 62 and the intermediate portion 63 of the first conductive layer 43 and the base 10, and the angle θ1 between the intermediate portion 63 and the base 10 satisfies θ1<90°, so that the corners of the resin layer 42 are formed with acute angles or curves, and it is possible to suppress breakage of the first conductive layer 43 at the corners of the resin layer 42. Therefore, it is possible to obtain a vibration device 1 with excellent reliability of electrical connection.

[0028] 2. Second embodiment Next, a vibration device 1a according to a second embodiment will be described with reference to FIG. FIG. 5 is an enlarged view of the vibration device 1a at the same position as part B in FIG.

[0029] The resonator device 1a of this embodiment is similar to the resonator device 1 of the first embodiment, except that the cross-sectional structure of the first conductive layer 43, which is the internal terminal 12a, is different from that of the resonator device 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment described above, and similar items will be denoted by the same reference numerals and their description will be omitted.

[0030] As shown in FIG. 5, the vibration device 1a includes a first conductive layer 43a, which is an internal terminal 12a, and includes a first portion 61 disposed on the base 10, a second portion 62 to which the metal bump 41 is bonded, and an intermediate portion 63a located between the first portion 61 and the second portion 62, and the resin layer 42 is disposed between the second portion 62 and the intermediate portion 63a of the first conductive layer 43a and the base 10. The intermediate portion 63a also includes a first straight portion 64 and a second straight portion 65 in a cross-sectional view, and an angle θ2 between the first straight portion 64 and the second straight portion 65 satisfies θ2>90°. That is, the corner of the resin layer 42 on the base 10 side is an acute angle with respect to the base 10, and the corner of the resin layer 42 on the vibration element 25 side is an obtuse angle, so that the breakage of the first conductive layer 43 can be suppressed compared to the case where the corner of the resin layer 42 is almost vertical.

[0031] With this configuration, the angle θ1 between the intermediate portion 63 and the base 10 satisfies θ1<90°, and the angle θ2 between the first straight portion 64 and the second straight portion 65 satisfies θ2>90°, so that the same effect as in the first embodiment can be obtained.

[0032] 3. Third embodiment Next, a vibration device 1b according to a third embodiment will be described with reference to FIGS. In FIG. 6, for the sake of convenience in explaining the internal configuration of the vibration device 1b, the cover 20 is removed.

[0033] The resonator device 1b of this embodiment is similar to the resonator device 1 of the first embodiment, except that the arrangement of the circuit section 50b of the base 10c is different from that of the resonator device 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment, and similar items will be denoted by the same reference numerals and their description will be omitted.

[0034] 6 and 7, the vibration device 1b includes a base 10c, a first conductive layer 43, a vibration element 25, metal bumps 41, a resin layer 42, and a lid 20. The base 10c and the lid 20 form a package 2a that houses the vibration element 25.

[0035] The base 10c has a circuit section 50b disposed on the first surface 10a side. The circuit section 50b has an oscillation circuit 51 electrically connected to the vibration element 25.

[0036] Moreover, the resin layer 42 is disposed between the second portion 62 and the intermediate portion 63 of the first conductive layer 43 and the base 10, the intermediate portion 63 of the first conductive layer 43 has a curved shape in a cross-sectional view, and the angle θ1 between the intermediate portion 63 and the base 10 satisfies θ1<90°. Therefore, the same effect as in the first embodiment can be obtained. [Explanation of symbols]

[0037] 1,1a,1b...vibration device, 2...package, 10...base, 10a...first surface, 10b...second surface, 12...internal terminal, 13...external terminal, 20...lid, 20a...third surface, 20b...fourth surface, 22...recess, 23...accommodation space, 25...vibration element, 30...element substrate, 31a...first electrode, 31b...second electrode, 32...excitation electrode, 33...lead electrode, 34...pad electrode, 35...side electrode, 41...metal bump, 41a...side, 42...resin layer, 43...first conductive layer, 44...second conductive layer, 50...circuit portion, 51...oscillating circuit, 61...first portion, 62...second portion, 63...middle portion, 64...first straight portion, 65...second straight portion, 66...outer portion, c1...central axis, θ1, θ2...angle.

Claims

1. a base having a first surface and a second surface in a reverse relationship; a first conductive layer disposed on the first surface; a vibration element located on the first surface side of the base, the vibration element including an element substrate and a second conductive layer located on a surface of the element substrate on the base side; a metal bump disposed between the base and the vibration element, joining the base and the vibration element and electrically connecting the first conductive layer and the second conductive layer; a resin layer disposed between the first conductive layer and the base; having The first conductive layer is A first portion disposed on the base; a second portion to which the metal bump is bonded; an intermediate portion located between the first portion and the second portion; Including, the resin layer is disposed between the second portion and the intermediate portion and the base, The angle θ1 between the intermediate portion and the base satisfies θ1<90°. Vibration devices.

2. The intermediate portion has a curved shape in cross section. The vibration device according to claim 1 .

3. a side surface of the metal bump on the base side has an outer shape portion that approaches a central axis of the metal bump from the vibration element side toward the base side in a cross-sectional view; an end portion of the second portion of the first conductive layer on the side of the intermediate portion is joined to the outer portion; The vibration device according to claim 1 .

4. The outer shape is an arc shape. The vibration device according to claim 3 .

5. The intermediate portion includes a first straight portion and a second straight portion in a cross-sectional view, The angle θ2 between the first straight portion and the second straight portion satisfies θ2>90°. The vibration device according to claim 1 .

6. a lid body joined to the base and housing the vibration element between the lid body and the base, The base includes a semiconductor substrate on which an oscillator circuit electrically connected to the vibration element is formed. A vibration device according to any one of claims 1 to 5.

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