Vibration device

Abstract

To provide a vibration device having a vibration element with a high Q-value.SOLUTION: A vibration device 1 includes: a base 10; and a vibration element 20 having a vibration unit 22 and a thin part 23, the vibration element also having an excitation electrode 31 formed in the inner side than the outer form of the vibration unit 22 in planer view. The vibration element 20 includes a first side 41 and a second side 42 opposed to the first side 41 and is joined to the base 10 by a metal bump 27 between the first side 41 and the vibration unit 22 in planer view. The vibration unit 22 includes a third side 43 located on the first side 41 side and a fourth side 44 located on the second side 42 side. The excitation electrode 31 includes a fifth side 45 along the third side 43 and a sixth side 46 along the fourth side 44. When the distance between the third side 43 and the fourth side 44 is denoted by L1, the distance between the third side 43 and the fifth side 45 is denoted by D1, and the distance between the fourth side 44 and the sixth side 46 is denoted by D2, at least one of 0.03≤D1 / L1≤0.07 and 0.03≤D2 / L1≤0.07 is satisfied.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A vibration device is known that includes a vibration element with a mesa structure having a vibrating vibration part and a thin-walled part that is thinner than the vibration part and integrated into the outer edge of the vibration part, thereby confining vibration energy in the vibration part and improving the Q value. For example, Patent Document 1 discloses a vibrator as a vibration device in which the amplitude of bending vibration generated in a vibrating piece is attenuated by optimizing the size of a bonding material that bonds a vibrating piece having a mesa structure as a vibration element to a base substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-152477 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the vibration device described in Patent Document 1 had the problem that when metal bumps were used as bonding materials, the hardness was greater than that of conductive adhesives, which significantly affected the vibration state of the vibration element, degrading the vibration characteristics and lowering the Q value. [Means for solving the problem]

[0005] The vibration device includes a base, a vibration part, and a vibration element having a thin portion that is thinner than the vibration part, and in a planar view, an excitation electrode is formed inside the outer shape of the vibration part, the vibration element includes a first side and a second side opposite the first side, and is joined to the base between the first side and the vibration part by a metal bump in a planar view, the vibration part includes a third side located on the first side side and a fourth side located on the second side side, the excitation electrode includes a fifth side along the third side and a sixth side along the fourth side, and when the distance between the third side and the fourth side is L1, the distance between the third side and the fifth side is D1, and the distance between the fourth side and the sixth side is D2, at least one of 0.03≦D1 / L1≦0.07 and 0.03≦D2 / L1≦0.07 is satisfied. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view showing a schematic structure of a vibration device according to a first embodiment. [Diagram 2] Cross-sectional view taken along line A1-A1 in Figure 1. [Diagram 3] FIG. 2 is a plan view showing a schematic structure of a vibration element included in the vibration device according to the first embodiment. [Figure 4] Cross-sectional view taken along line A2-A2 in Figure 3. [Diagram 5] 11 is a diagram showing the Q value of a vibration element relative to the distance between the outer shape of the vibration part and the outer shape of the excitation electrode. [Figure 6] FIG. 11 is a plan view showing a schematic structure of a vibration device according to a second embodiment. [Figure 7] 7 is a cross-sectional view taken along line B1-B1 in FIG. 6. [Figure 8] FIG. 11 is a plan view showing a schematic structure of a vibration element included in a vibration device according to a second embodiment. [Figure 9] 9 is a cross-sectional view taken along line B2-B2 in FIG. 8. [Figure 10] FIG. 11 is a plan view showing a schematic structure of a vibration device according to a third embodiment. [Figure 11] 11 is a cross-sectional view taken along line C1-C1 in FIG. 10 . [Figure 12]FIG. 11 is a plan view showing a schematic structure of a vibration element included in a vibration device according to a third embodiment. [Figure 13] 13 is a cross-sectional view taken along line C2-C2 in FIG. 12. [Figure 14] FIG. 13 is a plan view showing a schematic structure of a vibration device according to a fourth embodiment. [Figure 15] Cross-sectional view taken along line DD in Figure 14. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] 1. First embodiment First, a vibration device 1 according to a first embodiment will be described with reference to FIGS. For ease of explanation, the following figures show three mutually orthogonal 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 tip of the arrow in each axial direction is also called the "plus side", the base end is 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] As shown in Figures 1 and 2, the vibration device 1 has a base 10, a vibration element 20 arranged on a first surface 11 of the base 10, metal bumps 27 that join the vibration element 20 to the base 10, and a lid 16 that covers the vibration element 20 and is joined to the first surface 11 of the base 10.

[0009] The base 10 is a silicon substrate, and has a first surface 11 and a second surface 12, which are opposite surfaces. The vibration element 20 is joined to the first surface 11 by a metal bump 27, and two internal terminals 14 are provided. An oscillation circuit 13 electrically connected to the vibration element 20 is provided on the silicon substrate. In this embodiment, the oscillation circuit 13 is provided on the first surface 11 side of the base 10, which is a silicon substrate. In other words, the base 10 is a semiconductor integrated circuit substrate with the first surface 11 as an active surface. The oscillation circuit 13 oscillates the vibration element 20 to generate a frequency of a reference signal such as a clock signal. The oscillation circuit 13 and the internal terminal 14 are electrically connected to each other.

[0010] A plurality of external terminals 15 for outputting the frequency of a reference signal are provided on the second surface 12 of the base 10. The external terminals 15 are electrically connected to the oscillator circuit 13 by wiring or through electrodes (not shown). Note that the external terminals 15 may be disposed between the base 10 and the external terminals 15 via an insulating layer (not shown).

[0011] The lid 16 is provided with a recess 25 that opens to the base 10 side, and is joined to the first surface 11 of the base 10 via a joining member 17, and together with the base 10, forms an accommodation space 26 that accommodates the vibration element 20. The inside of the accommodation space 26 is in a reduced pressure state, preferably a state closer to a vacuum. This reduces viscous resistance and improves the oscillation characteristics of the vibration element 20. Silicon is preferable as a constituent material of the lid 16, but glass, ceramics, etc. may also be used.

[0012] 3 and 4, the vibration element 20 has a substrate 21 having a vibration portion 22, a thin portion 23, and a support portion 24, excitation electrodes 31 provided on the upper and lower surfaces of the vibration portion 22, and two pad electrodes 32 provided on the lower surface of the support portion 24. The vibration element 20 also has a first side 41 on the negative side in the X direction and a second side 42 on the opposite side to the first side 41, i.e., on the positive side in the X direction, and is joined to the base 10 by a metal bump 27 at the support portion 24 between the first side 41 and the vibration portion 22.

[0013] The substrate 21 is a rectangle whose length in the X direction is long, and has a vibrating portion 22, a thin portion 23 that is thinner than the vibrating portion 22, and a supporting portion 24 that is thicker than the thin portion 23. The supporting portion 24 is connected to the vibrating portion 22 via the thin portion 23, and is joined to the base 10 by a metal bump 27. The thin portion 23 is disposed so as to surround the vibrating portion 22 in a plan view, and is recessed to the same depth from the upper and lower surfaces of the vibrating portion 22. Thus, the substrate 21 has a double-sided mesa structure. The constituent material of the substrate 21 is quartz, and an AT-cut quartz substrate is preferable.

[0014] The excitation electrodes 31 provided on the upper and lower surfaces of the vibrating part 22 are formed inside the outer shape of the vibrating part 22 in a plan view, and the two excitation electrodes 31 are arranged so as to overlap. The excitation electrode 31 provided on the upper surface of the vibrating part 22 is electrically connected to one pad electrode 32 via a lead electrode 33 extending in the negative X-direction and a side electrode 34 provided on the side surface of the substrate 21 on the negative X-direction side. In addition, the excitation electrode 31 provided on the lower surface of the vibrating part 22 is electrically connected to the other pad electrode 32 via a lead electrode 33 extending in the negative X-direction side.

[0015] The two pad electrodes 32 of the vibration element 20 are disposed at positions overlapping with the two internal terminals 14 provided on the first surface 11 of the base 10, respectively, and are mechanically and electrically joined via metal bumps 27. Therefore, the excitation electrodes 31 provided on the upper and lower surfaces of the vibrating part 22 are electrically connected to the oscillation circuit 13 provided on the base 10, so that the vibration element 20 can be oscillated.

[0016] The vibration element 20 has a cantilever structure in which the support portion 24 arranged on the first side 41 side is joined to the base 10 by the metal bump 27, thereby making it possible to lengthen the distance from the metal bump 27 to the vibration portion 22 and reduce the effect on the vibration characteristics of the residual stress of the metal bump 27 due to the joining. Therefore, the longer the distance from the metal bump 27 to the vibration portion 22, the smaller the effect on the vibration characteristics. However, the length of the vibration element 20 in the X direction becomes longer, making miniaturization an issue.

[0017] Therefore, as a method for miniaturizing the vibration element 20 while improving the Q value of the vibration element 20, the influence of the distance between the outer shape of the vibration part 22, which is the mesa part, and the outer shape of the excitation electrode 31 on the Q value of the vibration element 20 was investigated.

[0018] As shown in Figure 3, when the distance between the third side 43 located on the first side 41 side of the vibration part 22 and the fourth side 44 located on the second side 42 side is L1, the distance between the fifth side 45 along the third side 43 of the excitation electrode 31 and the third side 43 of the vibration part 22 is D1, and the distance between the sixth side 46 along the fourth side 44 of the excitation electrode 31 and the fourth side 44 of the vibration part 22 is D2, the results of simulating the Q value of the vibration element 20 when the distance D1 or distance D2 is changed are shown in Figure 5.

[0019] The dimensions of each part of the vibration element 20 used in the simulation, shown in Figures 3 and 4, are L = 720 μm, L1 = 453 μm, L2 = 89 μm, L3 = 90 μm, M = 493 μm, M1 = 31.5 μm, t1 = 28.5 μm, h1 = 2 μm, and the simulation was performed by changing D1 and D2 from 0 μm to 43.5 μm.

[0020] 5, the horizontal axis represents D1 / L1 or D2 / L1 with the distance L1 as a reference, and the vertical axis represents Q / Q0 with the Q value of the vibration element 20 when the distances D1 and D2 are zero as a reference, and the results of simulating the Q value versus D1 / L1 or D2 / L1 are plotted to show an approximation curve. Note that this simulation is performed for the case where the distances D1 and D2 are the same value, and for the case where the length h1 of the step on the upper surface and the length of the step on the lower surface are the same value.

[0021] 5, as D1 / L1 or D2 / L1 increases, Q / Q0 increases from around 0.025, and reaches a maximum value at around 0.048. After that, Q / Q0 tends to decrease as D1 / L1 or D2 / L1 increases.

[0022] As shown in Figure 5, when the relationship between the distance L1 and the distances D1 and D2 satisfies 0.03≦D1 / L1≦0.07 and 0.03≦D2 / L1≦0.07, the Q value can be increased to 1.2 times or more compared to the Q0 value of the vibration element 20 when the distances D1 and D2 are zero.

[0023] Furthermore, as shown in Figure 5, when the relationship between the distance L1 and the distances D1 and D2 satisfies 0.036≦D1 / L1≦0.062 and 0.036≦D2 / L1≦0.062, the Q value can be increased by more than three times compared to the Q0 value of the vibration element 20 when the distances D1 and D2 are zero.

[0024] Furthermore, as shown in FIG. 5, when the relationship between the distance L1 and the distances D1 and D2 satisfies 0.04≦D1 / L1≦0.058 and 0.04≦D2 / L1≦0.058, the Q value can be increased by more than five times compared to the Q0 value of the vibration element 20 when the distances D1 and D2 are zero.

[0025] Therefore, by setting the distance D1 and the distance D2, which are the distances between the outer shape of the vibration part 22 and the outer shape of the excitation electrode 31, within the above-mentioned range, the vibration energy can be efficiently confined within the excitation electrode 31 area, so that even when joined with the metal bump 27, which has a higher hardness than the conductive adhesive, the Q value of the vibration element 20 can be made larger than the Q0 value of the vibration element 20 when the distance D1 and the distance D2 are zero. Note that even when either one of the distances D1 and D2 is set within the above-mentioned range, the Q value of the vibration element 20 can be made larger than the Q0 value of the vibration element 20 when the distances D1 and D2 are zero.

[0026] As described above, in the vibration device 1 of this embodiment, the relationship between the distance L1 between the third side 43 and the fourth side 44, the distance D1 between the third side 43 and the fifth side 45, and the distance D2 between the fourth side 44 and the sixth side 46 satisfies at least one of 0.03≦D1 / L1≦0.07 and 0.03≦D2 / L1≦0.07, so that the Q value can be increased compared to the Q0 value of the vibration element 20 when the distance D1 and the distance D2 are zero. Therefore, the Q value can be improved by the vibration energy trapping effect rather than the deterioration of the Q value caused by bonding the vibration element 20 of the mesa structure to the base 10 with the metal bump 27, which has a higher hardness than the conductive adhesive, and the vibration device 1 including the vibration element 20 having a high Q value can be obtained.

[0027] Furthermore, since the relationship between the distance L1 and the distances D1 and D2 satisfies at least one of 0.036≦D1 / L1≦0.062 and 0.036≦D2 / L1≦0.062, the Q value can be made larger than the Q0 value when the distances D1 and D2 are zero.

[0028] Furthermore, since the relationship between the distance L1 and the distances D1 and D2 satisfies at least one of 0.04≦D1 / L1≦0.058 and 0.04≦D2 / L1≦0.058, the Q value can be made significantly larger than the Q0 value when the distances D1 and D2 are zero.

[0029] 2. Second embodiment Next, a vibration device 1a according to a second embodiment will be described with reference to FIGS.

[0030] The vibration device 1a of this embodiment is similar to the vibration device 1 of the first embodiment, except that the structure of the vibration element 20a is different from that of the vibration device 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment, and descriptions of similar points will be omitted.

[0031] As shown in Figures 6 and 7, the vibration device 1a has a base 10, a vibration element 20a arranged on a first surface 11 of the base 10, metal bumps 27 that join the vibration element 20a to the base 10, and a lid 16 that covers the vibration element 20a and is joined to the first surface 11 of the base 10.

[0032] 8 and 9, the substrate 21a of the vibration element 20a is a rectangle whose length in the X direction is long, and has a vibration section 22, a thin section 23 that is thinner than the vibration section 22, and a support section 24a that has the same thickness as the thin section 23. In addition, the support section 24a is connected to the vibration section 22 via the thin section 23.

[0033] In the vibration device 1a of this embodiment, the support portion 24a of the vibration element 20a has the same thickness as the thin-walled portion 23, but by setting the distance D1 and distance D2, which are the distances between the outer shape of the vibration portion 22 and the outer shape of the excitation electrode 31, within a predetermined range, it is possible to obtain the same effect as in the first embodiment.

[0034] 3. Third embodiment Next, a vibration device 1b according to a third embodiment will be described with reference to FIGS.

[0035] The resonator device 1b of this embodiment is similar to the resonator device 1 of the first embodiment, except that the structure of the resonator element 20b 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 descriptions of similar matters will be omitted.

[0036] As shown in Figures 10 and 11, the vibration device 1b has a base 10, a vibration element 20b arranged on a first surface 11 of the base 10, metal bumps 27 that join the vibration element 20b to the base 10, and a lid 16 that covers the vibration element 20b and is joined to the first surface 11 of the base 10.

[0037] 12 and 13, the substrate 21b of the vibration element 20b is a rectangle whose length in the X direction is long, and has a vibration part 22b, a thin part 23b that is thinner than the vibration part 22b, and a support part 24b that is thicker than the thin part 23b. The support part 24b is connected to the vibration part 22b via the thin part 23b.

[0038] In the vibration element 20b, the thin portion 23b is disposed so as to surround the vibration portion 22b in a plan view and is recessed from the lower surface of the vibration portion 22b. Therefore, the substrate 21b has a single-sided mesa structure in which the upper surface side is flat and the lower surface side has a mesa portion.

[0039] In the vibration device 1b of this embodiment, the vibration element 20b has a single-sided mesa structure, but by setting the distance D1 and distance D2, which are the distances between the outline of the vibration part 22b and the outline of the excitation electrode 31, within a predetermined range, it is possible to obtain the same effect as in the first embodiment.

[0040] 4. Fourth embodiment Next, a vibration device 1c according to a fourth embodiment will be described with reference to FIGS.

[0041] The resonator device 1c of this embodiment is similar to the resonator device 1 of the first embodiment, except that a quartz substrate 18 is disposed between the metal bumps 27 and the base 10. The following description will focus on the differences from the first embodiment, and will omit a description of the similar points.

[0042] 14 and 15, the vibration device 1c includes a base 10, a vibration element 20 disposed on a first surface 11 of the base 10, metal bumps 27 that bond the vibration element 20 to the base 10, a quartz substrate 18 disposed between the metal bumps 27 and the base 10, and a lid 16 that covers the vibration element 20 and is bonded to the first surface 11 of the base 10. The vibration element 20 is a quartz vibration element.

[0043] In the resonator device 1c, a quartz substrate 18 is disposed between the metal bumps 27 and the base 10. The quartz substrate 18 is bonded to the base 10 via a bonding member 19. Therefore, compared to a case where the resonator element 20 is directly bonded to the base 10 by the metal bumps 27, it is possible to reduce stress caused by a difference in linear expansion coefficient between the base 10 and the resonator element 20. It is preferable that the crystal direction of the quartz substrate 18 is the same as the crystal direction of the resonator element 20. By making the crystal directions the same, it is possible to further reduce stress caused by a difference in linear expansion coefficient between the base 10 and the resonator element 20.

[0044] In the vibration device 1c of this embodiment, a quartz substrate 18 is arranged between the metal bump 27 and the base 10, so that the stress caused by the difference in linear expansion coefficient between the base 10 and the vibration element 20 can be reduced, and by setting the distance D1 and distance D2, which are the distances between the outline of the vibration part 22 and the outline of the excitation electrode 31, within a predetermined range, an effect equivalent to that of the first embodiment can be obtained.

[0045] 5. Variations The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. In the above-described first to fourth embodiments, the case where the oscillation circuit 13 is formed on the first surface 11 side of the base 10 has been described, but the oscillation circuit 13 may be formed on the second surface 12 side of the base 10. In this case, a through electrode may be further formed in the base 10, which penetrates from the first surface 11 to the second surface 12 of the base 10 and electrically connects between the vibration element 20 and the oscillation circuit 13. [Explanation of symbols]

[0046] 1, 1a, 1b, 1c...vibration device, 10...base, 11...first surface, 12...second surface, 13...oscillating circuit, 14...internal terminal, 15...external terminal, 16...lid, 17...jointing member, 18...quartz substrate, 19...jointing member, 20...vibration element, 21...substrate, 22...vibrating portion, 23...thin portion, 24...support portion, 25...recess, 26...accommodation space, 27...metal bump, 31...excitation electrode, 32...pad electrode, 33...lead electrode, 34...side electrode, 41...first side, 42...second side, 43...third side, 44...fourth side, 45...fifth side, 46...sixth side, D1, D2, L1...distance.

Claims

1. With the base, a vibration element having a vibration section and a thin-walled section having a thickness smaller than that of the vibration section, and an excitation electrode formed inside an outer shape of the vibration section in a plan view; the vibration element includes a first side and a second side opposite to the first side, and is joined to the base by a metal bump between the first side and the vibration portion in a plan view; the vibration portion includes a third side located on the first side and a fourth side located on the second side, the excitation electrode includes a fifth side along the third side and a sixth side along the fourth side, The distance between the third side and the fourth side is L1, The distance between the third side and the fifth side is D1, When the distance between the fourth side and the sixth side is D2, At least one of 0.03≦D1 / L1≦0.07 and 0.03≦D2 / L1≦0.07 is satisfied; Vibration devices.

2. The L1, the D1, and the D2 are At least one of 0.036≦D1 / L1≦0.062 and 0.036≦D2 / L1≦0.062 is satisfied, The vibration device according to claim 1 .

3. The L1, the D1, and the D2 are At least one of 0.04≦D1 / L1≦0.058 and 0.04≦D2 / L1≦0.058 is satisfied, The vibration device according to claim 1 .

4. a support portion connected to the vibration portion via the thin portion and thicker than the thin portion; The support portion is joined to the base by the metal bump. The vibration device according to claim 1 .

5. The base comprises a silicon substrate. A vibration device according to any one of claims 1 to 4.

6. a lid body bonded to the silicon substrate and housing the vibration element between the lid body and the silicon substrate; the silicon substrate includes a first surface and a second surface opposite the first surface; The vibration element is bonded to the first surface side by the metal bump, An oscillator circuit electrically connected to the vibration element is formed on the silicon substrate. The vibration device according to claim 5 .

7. The vibration element is a quartz crystal vibration element, A quartz substrate is provided between the metal bumps and the base. The vibration device according to claim 1 .

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