Resonator element and resonator device

Abstract

The invention provides a resonator element and a resonator device, which ensure the adhesion of electrodes and have excellent vibration characteristics. The resonator element includes: a substrate made of quartz; and an electrode disposed on the surface of the substrate, the electrode including an upper electrode layer and a base electrode layer disposed between the substrate and the upper electrode layer, the electrode including, in plan view, a first region (21) in which the base electrode layer is dispersed in an island shape and the area ratio of the base electrode layer per unit area is 10% or more and less than 50%.

Description

Technical Field

[0001] The present invention relates to a vibration plate and a vibration device. Background Art

[0002] For example, Patent Document 1 discloses an inverse mesa-type piezoelectric vibrating piece, which has a thin-walled portion as a vibration region in the central portion of the piezoelectric plate, and a thick-walled portion formed around the entire circumference or a portion of the thin-walled portion to reinforce the thin-walled portion, wherein a contact metal composed of a plurality of separate metal thin films is provided on the entire surface of the piezoelectric plate. When a conductive adhesive is applied to the thick-walled portion of the piezoelectric vibrating piece, the surface tension acts on the conductive adhesive due to the plurality of concavo-convexities of the contact metal, thereby preventing the conductive adhesive from flowing from the inclined portion between the thick-walled portion and the thin-walled portion into the vibration region of the thin-walled portion.

[0003] Patent document 1: WO2014 / 006868

[0004] However, the piezoelectric vibrating piece described in Patent Document 1, in addition to being able to prevent the conductive adhesive from flowing into the vibration area, does not describe the effect of the amount of contact metal on the vibration characteristics, especially the effect of the amount of contact metal under the electrode on the vibration characteristics. For example, when the amount of contact metal under the electrode is small, the electrode is easily peeled off, and when the amount of contact metal under the electrode is large, the vibration characteristics are degraded due to the diffusion of the contact metal to the electrode. In addition, when the contact metal is formed on the entire surface, the vibration characteristics may be degraded due to film stress. Summary of the invention

[0005] The vibrating piece comprises: a substrate made of quartz; and an electrode arranged on the surface of the substrate, the electrode comprising an upper electrode layer and a base electrode layer arranged between the substrate and the upper electrode layer, and when viewed from above, the electrode comprises a first area, in which the base electrode layer is dispersed in an island shape, and the area ratio of the base electrode layer per unit area is greater than 10% and less than 50%.

[0006] The vibration device comprises: the vibration piece described above; a package having a terminal; and a metal bump connecting the mounting electrode and the terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a plan view showing a schematic structure of the vibration device according to the first embodiment.

[0008] Figure 2 yes Figure 1 Cross-sectional view at line A1-A1.

[0009] Figure 3It is a plan view showing a schematic structure of a vibrating element included in the vibrating device according to the first embodiment.

[0010] Figure 4 yes Figure 3 Cross-sectional view at line A2-A2.

[0011] Figure 5 It is a graph showing the relationship between the sheet resistance ratio and the area ratio of the base electrode layer.

[0012] Figure 6 It is a plan view showing a schematic structure of a vibrator element included in the vibrator device according to the second embodiment.

[0013] Figure 7 yes Figure 6 A cross-sectional view taken along the A3-A3 line.

[0014] Figure 8 It is a plan view showing a schematic structure of a vibrator element included in the vibrator device according to the third embodiment.

[0015] Fig. 9 yes Figure 8 A cross-sectional view taken along the A4-A4 line.

[0016] Fig.10 It is a plan view showing a schematic structure of a vibrator element included in the vibrator device according to the fourth embodiment.

[0017] Fig.11 yes Fig.10 Cross-sectional view at line A5-A5.

[0018] Description of symbols

[0019] 1, 1a, 1b, 1c: vibration device; 2: package; 3, 3a, 3b, 3c: vibration piece; 10: base substrate; 11: terminal; 13: third surface; 14: fourth surface; 15: external terminal; 16: cover; 17: recess; 18: storage space; 19: bonding part; 20: electrode; 21: first area; 22: second area; 23: upper electrode layer; 24: base electrode layer; 30: substrate; 31: first surface; 32: second surface; 33: excitation electrode; 34: lead-out electrode; 35: side electrode; 36: mounting electrode; 38: metal bump. DETAILED DESCRIPTION

[0020] 1. First Implementation

[0021] First, regarding the vibration device 1 of the first embodiment, a vibration element in which the vibration piece 3 is housed in the package 2 is taken as an example. Figure 1 and Figure 2 Provide explanation.

[0022] In addition, Figure 1 In order to facilitate the description of the internal structure of the vibration device 1, the state in which the cover 16 is removed is shown. Figure 5 In the following figures, the X-axis, Y-axis, and Z-axis are shown as three axes perpendicular to each other. In addition, 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". In addition, the front end side of the arrow in each axis direction is also called the "positive side", the base end side is called the "negative side", and the positive side in the Z direction is called the "up".

[0023] like Figure 1 and Figure 2 As shown, the vibration device 1 of the present embodiment includes a package 2 , a vibration piece 3 housed in the package 2 , and metal bumps 38 .

[0024] The package 2 is composed of a base substrate 10 and a lid 16 .

[0025] The base substrate 10 has a third surface 13 and a fourth surface 14 in a front-back relationship, and the third surface 13 is opposite to the second surface 32 of the vibration piece 3. On the third surface 13, two terminals 11 for bonding the vibration piece 3 are arranged along the Y direction, and a plurality of external terminals 15 for supplying power and outputting frequency are provided on the fourth surface 14. In addition, the terminal 11 and the external terminal 15 are electrically connected through wiring and through electrodes not shown. In addition, as a constituent material of the base substrate 10, silicon is preferred, and glass, ceramic, etc. may also be used.

[0026] The cover 16 is provided with a recess 17 opened toward the base substrate 10, and is bonded to the third surface 13 of the base substrate 10 via a bonding component 19, and together with the base substrate 10, forms a storage space 18 for storing the vibration piece 3. In addition, the cover 16 and the base substrate 10 may be bonded directly without using the bonding component 19. In addition, the storage space 18 is in a reduced pressure state, preferably a state closer to a vacuum. As a result, the viscous resistance is reduced, and the oscillation characteristics of the vibration piece 3 are improved. In addition, as a constituent material of the cover 16, silicon is preferred, but glass, ceramics, etc. may also be used.

[0027] The vibrating element 3 includes a substrate 30 and an electrode 20 .

[0028] The substrate 30 is rectangular in a plan view, with the X direction as the long side direction, the Y direction as the short side direction, and the Z direction as the thickness direction. In addition, the substrate 30 has a first surface 31 and a second surface 32 in a front-back relationship, and the electrodes 20 are formed on the surfaces of the first surface 31 and the second surface 32, and the second surface 32 is opposite to the third surface 13 of the base substrate 10. In addition, the constituent material of the substrate 30 is quartz, preferably an AT-cut quartz substrate.

[0029] The electrode 20 includes an excitation electrode 33, a mounting electrode 36, and an extraction electrode 34 connecting the excitation electrode 33 and the mounting electrode 36, and the excitation electrode 33 and the extraction electrode 34 are provided on the first surface 31 of the substrate 30. The excitation electrode 33, the extraction electrode 34, and two mounting electrodes 36 arranged along the Y direction are provided on the second surface 32 of the substrate 30. In addition, the excitation electrode 33 provided on the first surface 31 of the substrate 30 is electrically connected to the mounting electrode 36 provided on the second surface 32 via the extraction electrode 34 and the side electrode 35 provided on the side surface on the negative side of the substrate 30 in the X direction. In addition, the excitation electrode 33 provided on the first surface 31 and the excitation electrode 33 provided on the second surface 32 are arranged to overlap when viewed from above.

[0030] The metal bump 38 is disposed between the mounting electrode 36 of the vibration piece 3 and the terminal 11 on the base substrate 10, electrically connects the mounting electrode 36 and the terminal 11, and joins the vibration piece 3 and the base substrate 10. The metal bump 38 is made of Au, Cu, solder, etc., and Au is preferably used because it is not easily affected by oxidation.

[0031] Alternatively, a conductive adhesive may be used instead of the metal bumps 38 . The conductive adhesive can increase the bonding strength by increasing the diameter, and is suitable for bonding a small-sized vibrating element 3 to the base substrate 10 .

[0032] Next, refer to Figure 3 and Figure 4 The resonator element 3 included in the resonator device 1 according to the present embodiment will be described.

[0033] like Figure 3 and Figure 4 As shown, the resonator element 3 included in the resonator device 1 of the present embodiment has electrodes 20 arranged on the surfaces of the first surface 31 and the second surface 32 of the substrate 30 .

[0034] The electrode 20 includes an upper electrode layer 23 and a base electrode layer 24 disposed between the substrate 30 and the upper electrode layer 23, and is composed of an excitation electrode 33, a mounting electrode 36, and an extraction electrode 34 connecting the excitation electrode 33 and the mounting electrode 36. When viewed from above, the base electrode layer 24 of the region of the excitation electrode 33 of the first region 21 of the electrode 20 is scattered in an island shape. In addition, in the present embodiment, the shape of the island of the base electrode layer 24 is a quadrilateral, but it is not limited to this, and it can also be a triangle, a polygon, a circle, an ellipse, etc. In addition, the size of the island of the base electrode layer 24 may not be fixed.

[0035] The constituent material of the upper electrode layer 23 is Au, Pt, Ag, Cu, etc., and Au is preferred because it is less susceptible to oxidation and the like and has excellent aging characteristics.

[0036] The constituent material of the base electrode layer 24 is Cr, Ti, TiW, Ni, or the like, and Cr is preferred because it further improves the adhesion of the electrode 20 .

[0037] Next, refer to Figure 5 The relationship between the area ratio per unit area of ​​the foundation electrode layer 24 in the first region 21 and the sheet resistance ratio of the electrode 20 will be described.

[0038] Figure 5 This is a diagram depicting the results of simulating the sheet resistance ratio of the electrode 20 relative to the area ratio per unit area of ​​the base electrode layer 24, based on the sheet resistance value of the electrode 20 with an area ratio of 100%. In addition, the simulation is as follows: the base electrode layer 24 is Cr with a film thickness of 7.5nm, and the upper electrode layer 23 is Au with a film thickness of 200nm.

[0039] according to Figure 5 As the area ratio of the base electrode layer 24 decreases, the sheet resistance ratio of the electrode 20 decreases. This is because, as the area ratio of the base electrode layer 24 decreases, the amount of Cr diffused from the base electrode layer 24 to the Au of the upper electrode layer 23 decreases, and the sheet resistance value of the electrode 20 decreases. If the area ratio of the base electrode layer 24 is less than 50%, the sheet resistance ratio of the electrode 20 can be made less than 0.4. In addition, when the area ratio of the base electrode layer 24 is less than 10%, the sheet resistance ratio of the electrode 20 can be further reduced, but the adhesion of the electrode 20 to the substrate 30 is reduced, and there is a possibility of peeling.

[0040] Therefore, in the present embodiment, the area ratio of the base electrode layer 24 per unit area of ​​the first region 21 which is the region of the excitation electrodes 33 is set to 10% or more and less than 50%.

[0041] Furthermore, by setting the area ratio of the base electrode layer 24 per unit area of ​​the region where the electrode 36 is mounted to 100%, the amount of Cr of the base electrode layer 24 diffused to the surface of the upper electrode layer 23 can be increased.

[0042] In this case, by using a conductive adhesive having good adhesion to Cr instead of the metal bumps 38 , the adhesion and bonding strength between the electrode 20 and the substrate 30 can be further improved.

[0043] In this embodiment, the vibrator having the vibrating piece 3 of the thickness shear vibration system is described as an example, but the present invention is not limited thereto and may be a vibrator of a tuning fork type vibrating piece having a bending vibration system. In addition, an oscillator in which the vibrating piece 3 and the oscillation circuit are housed in the package 2 may be used.

[0044] As described above, the vibration piece 3 of the present embodiment has the electrode 20 including the first region 21, in which the base electrode layer 24 is dispersed in an island shape in the first region 21 when viewed from above, and the area ratio of the base electrode layer 24 per unit area is 10% or more and less than 50%, so that the adhesion of the electrode 20 can be ensured, and the increase in the sheet resistance value of the electrode 20 caused by the diffusion of the base electrode layer 24 can be suppressed, thereby suppressing the degradation of the vibration characteristics. Therefore, the vibration device 1 having the vibration piece 3 of the present embodiment is excellent in reliability and vibration characteristics.

[0045] 2. Second Implementation

[0046] Next, refer to Figure 6 and Figure 7 The vibration piece 3a included in the vibration device 1a of the second embodiment is described. The vibration device 1a of this embodiment is the same as the vibration device 1 of the first embodiment except that the structure of the electrode 20a of the vibration piece 3a is different. The description will be centered on the differences from the first embodiment described above, and the description of the same matters will be omitted.

[0047] like Figure 6 and Figure 7 As shown, in the vibration piece 3a possessed by the vibration device 1a of the present embodiment, the base electrode layer 24 is dispersed in an island shape and the area ratio of the base electrode layer 24 per unit area is greater than 10% and less than 50%. The first region 21a is the region of the excitation electrode 33 and the lead-out electrode 34, and the area ratio of the base electrode layer 24 per unit area of ​​the base electrode layer 24 in the region of the mounting electrode 36 is 100%.

[0048] By adopting such a structure, the sheet resistance in the region of the extraction electrode 34 can be reduced, and the same effect as that of the first embodiment can be obtained.

[0049] 3. Third Implementation

[0050] Next, refer to Figure 8 and Fig. 9 The vibration piece 3b of the vibration device 1b of the third embodiment is described. The vibration device 1b of this embodiment is the same as the vibration device 1 of the first embodiment except that the structure of the electrode 20b of the vibration piece 3b is different. In addition, the description is centered on the differences from the first embodiment described above, and the description of the same matters is omitted.

[0051] like Figure 8 as well as Fig. 9As shown, in the vibration piece 3b of the vibration device 1b of this embodiment, the base electrode layer 24 is dispersed in an island shape and the area ratio of the base electrode layer 24 per unit area is greater than 10% and less than 50%. The first area 21b is the area of ​​the excitation electrode 33, the lead-out electrode 34 and the mounting electrode 36.

[0052] With such a structure, all electrode regions can be formed under the same conditions, so electrode formation becomes easy and the same effects as those of the first embodiment can be obtained.

[0053] 4. Fourth Implementation

[0054] Next, refer to Fig.10 and Fig.11 The vibration piece 3c of the vibration device 1c of the fourth embodiment is described. In addition, the vibration device 1c of this embodiment is the same as the vibration device 1 of the first embodiment except that the structure of the electrode 20c of the vibration piece 3c and the use of a conductive adhesive instead of the metal bump 38. In addition, the description is centered on the differences from the first embodiment described above, and the description of the same matters is omitted.

[0055] like Fig.10 and Fig.11 As shown, in the vibration piece 3c possessed by the vibration device 1c of the present embodiment, the base electrode layer 24 is dispersed in an island shape, and the area ratio of the base electrode layer 24 per unit area is greater than 10% and less than 50%. The first region 21c is the region of the excitation electrode 33 and the lead-out electrode 34, and the base electrode layer 24 in the region of the mounting electrode 36 of the second region 22 is dispersed in an island shape, and the area ratio of the base electrode layer 24 per unit area is greater than 50%.

[0056] By forming such a structure, the amount of Cr of the base electrode layer 24 diffused toward the surface of the upper electrode layer 23 can be increased at the mounting electrode 36, the close adhesion with the conductive adhesive can be ensured, and the sheet resistance in the area of ​​the excitation electrode 33 and the lead-out electrode 34 can be reduced, thereby achieving the same effect as the first embodiment.

Claims

1. A vibrating plate, comprising: a substrate composed of quartz; and an electrode disposed on a surface of the substrate, The electrode comprises an upper electrode layer and a base electrode layer arranged between the substrate and the upper electrode layer. When viewed in a plan view, the electrode includes a first region in which the base electrode layer is dispersed in an island shape and an area ratio of the base electrode layer per unit area is 10% or more and less than 50%.

2. The vibrating piece according to claim 1, wherein: The material of the base electrode layer is Cr.

3. The vibrating piece according to claim 2, wherein: The material of the upper electrode layer is Au.

4. The vibrating piece according to any one of claims 1 to 3, wherein: The electrodes include an excitation electrode, a mounting electrode, and an extraction electrode connecting the excitation electrode and the mounting electrode. The first region is included in at least the excitation electrode of the excitation electrode and the extraction electrode.

5. The vibrating piece according to claim 4, wherein: The first region is also included in the mounting electrode.

6. The vibrating piece according to claim 4, wherein: The electrode includes a second region whose area ratio per unit area of ​​the base electrode layer is 50% or more, The second region is included in the mounting electrode.

7. A vibration device, comprising: The vibrating plate according to claim 4; a package having terminals; and A conductive adhesive connects the mounting electrode and the terminal.

8. A vibration device, comprising: The vibrating plate according to claim 6; a package having terminals; and A metal bump connects the mounting electrode and the terminal.

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