Vibration piece and vibration device

Abstract

To provide a vibration piece and a vibration device, in which an adhesion of an electrode is secured, and which have an excellent vibration characteristic.SOLUTION: A vibration piece 3 comprises: a substrate 30 formed by a crystal; and an electrode 20 that is arranged to a front surface of the substrate 30. The electrode 20 contains an underground electrode layer 24 that is arranged to between an upper electrode layer 23, the substrate 30, and the upper electrode layer 23. In the electrode 20, the underground electrode layer 24 is scattered / attached an island shape in a plan view, and a first region 21 where an area ratio of the underground electrode layer 24 per a unit area is 10% or more and is less than 50% is contained.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vibrating element and a vibrating device. [Background technology]

[0002] For example, Patent Document 1 discloses an inverted mesa type piezoelectric vibrating piece having a thin portion as a vibration region in the center of the piezoelectric plate and a thick portion formed all around or partially around the thin portion to reinforce the thin portion, in which contact metal consisting of many separated metal thin films is provided on the entire surface of the piezoelectric plate. When a conductive adhesive is applied to the thick portion of this piezoelectric vibrating piece, the many projections and recesses of the contact metal act as a surface tension on the conductive adhesive, preventing the conductive adhesive from flowing into the vibration region of the thin portion from the inclined portion between the thick and thin portions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2014 / 006868 issue Summary of the Invention [Problem to be solved by the invention]

[0004] However, the piezoelectric vibrating piece described in Patent Document 1, apart from being able to prevent the conductive adhesive from flowing into the vibration region, does not mention the effect of the amount of contact metal on vibration characteristics, particularly the effect of the amount of contact metal under the electrode on vibration characteristics. For example, if the amount of contact metal under the electrode is small, the electrode is likely to peel off, and if it is large, the vibration characteristics will deteriorate due to the diffusion of the contact metal into the electrode. Furthermore, if a contact metal film is formed over the entire surface, the vibration characteristics may deteriorate due to film stress. [Means for solving the problem]

[0005] The vibrating piece comprises a substrate made of quartz crystal and an electrode arranged on a surface of the substrate, the electrode including an upper electrode layer and a base electrode layer arranged between the substrate and the upper electrode layer, the electrode including a first region in which the base electrode layer is scattered in an island-like manner in a planar view and the area ratio of the base electrode layer per unit area is 10% or more and less than 50%.

[0006] The vibrating device includes the vibrating piece described above, a package having terminals, and metal bumps connecting the mount electrodes and the terminals. [Brief description of the drawings]

[0007] [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 vibrating element included in the vibrating device according to the first embodiment. [Figure 4] Cross-sectional view taken along line A2-A2 in Figure 3. [Diagram 5] FIG. 13 is a graph showing the relationship between the sheet resistance ratio and the area ratio of a base electrode layer. [Figure 6] FIG. 11 is a plan view showing a schematic structure of a vibrating element included in a vibrating device according to a second embodiment. [Figure 7] Cross-sectional view taken along line A3-A3 in Figure 6. [Figure 8] FIG. 11 is a plan view showing a schematic structure of a vibrating element included in a vibrating device according to a third embodiment. [Figure 9] Cross-sectional view taken along line A4-A4 in Figure 8. [Figure 10] FIG. 13 is a plan view showing a schematic structure of a vibrating element included in a vibrating device according to a fourth embodiment. [Figure 11] Cross-sectional view taken along line A5-A5 in Figure 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 1. First embodiment First, a resonator in which a resonator element 3 is housed in a package 2 will be taken as an example of a resonator device 1 according to a first embodiment and will be described with reference to FIGS. 1 and 2. FIG. In addition, in FIG. 1, for convenience of explanation of the internal configuration of the vibration device 1, the cover 16 is removed. Also, for convenience of explanation, in each of the subsequent figures except for FIG. 5, the X-axis, the Y-axis, and the Z-axis are illustrated as three mutually perpendicular axes. Also, 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". Also, the tip side of the arrow in each axial direction is called the "plus side", the base end side is called the "minus side", and the plus side of the Z direction is called the "up".

[0009] As shown in FIGS. 1 and 2, a resonator device 1 of the present embodiment includes a package 2, a resonator element 3 housed in the package 2, and metal bumps .

[0010] The package 2 is composed of a base substrate 10 and a lid 16 . The base substrate 10 has a third surface 13 and a fourth surface 14, which are opposite surfaces, and the third surface 13 faces the second surface 32 of the vibrating bar 3. On the third surface 13, two terminals 11 for joining the vibrating bar 3 are arranged side by side along the Y direction, and on the fourth surface 14, a plurality of external terminals 15 are provided for supplying power and outputting frequencies. The terminals 11 and the external terminals 15 are electrically connected by wiring or through electrodes (not shown). Silicon is suitable as a material for forming the base substrate 10, but glass, ceramics, etc. may also be used.

[0011] The lid 16 is provided with a recess 17 that opens to the base substrate 10 side, and is joined to the third surface 13 of the base substrate 10 via a joining member 19, and together with the base substrate 10, forms an accommodation space 18 that accommodates the vibrating element 3. The lid 16 and the base substrate 10 may be joined directly without using the joining member 19. The accommodation space 18 is in a reduced pressure state, preferably a state closer to a vacuum. This reduces viscous resistance and improves the oscillation characteristics of the vibrating element 3. Silicon is a suitable material for the lid 16, but glass, ceramics, etc. may also be used.

[0012] The vibrator element 3 has a substrate 30 and an electrode 20 . The substrate 30 is rectangular in plan view, with the X direction being the long side direction, the Y direction being the short side direction, and the Z direction being the thickness direction. The substrate 30 has a first surface 31 and a second surface 32 which are opposite sides, with electrodes 20 formed on the surfaces of the first surface 31 and the second surface 32, and the second surface 32 facing the third surface 13 of the base substrate 10. The material constituting the substrate 30 is quartz, and an AT-cut quartz substrate is preferable.

[0013] The electrode 20 includes an excitation electrode 33, a mount electrode 36, and an extraction electrode 34 connecting the excitation electrode 33 and the mount electrode 36, and the first surface 31 of the substrate 30 is provided with the excitation electrode 33 and the extraction electrode 34. The second surface 32 of the substrate 30 is provided with the excitation electrode 33, the extraction electrode 34, and two mount electrodes 36 arranged along the Y direction. The excitation electrode 33 provided on the first surface 31 of the substrate 30 is electrically connected to the mount electrode 36 provided on the second surface 32 via the extraction electrode 34 and a side electrode 35 provided on the side surface of the substrate 30 on the negative side in the X direction. The excitation electrode 33 provided on the first surface 31 and the excitation electrode 33 provided on the second surface 32 are arranged so as to overlap each other in a plan view.

[0014] The metal bumps 38 are disposed between the mount electrodes 36 of the vibrating element 3 and the terminals 11 on the base substrate 10, electrically connecting the mount electrodes 36 and the terminals 11 and joining the vibrating element 3 to the base substrate 10. The constituent materials of the metal bumps 38 are Au, Cu, solder, etc., and Au is preferable because it is less susceptible to the effects of oxidation, etc. Moreover, a conductive adhesive can be used instead of the metal bumps 38. The conductive adhesive can improve the adhesive strength by increasing the diameter, and is suitable for bonding a small resonator element 3 to the base substrate 10.

[0015] Next, the vibrator element 3 included in the vibrator device 1 of this embodiment will be described with reference to FIGS. The vibrating element 3 included in the vibrating device 1 of this embodiment has electrodes 20 arranged on the surfaces of a first surface 31 and a second surface 32 of a substrate 30, as shown in FIGS.

[0016] 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 configured of an excitation electrode 33, a mount electrode 36, and an extraction electrode 34 connecting the excitation electrode 33 and the mount electrode 36. In a plan view, the electrode 20 has the base electrode layer 24 in the region of the excitation electrode 33, which is the first region 21, scattered in an island shape. In this embodiment, the shape of the islands of the base electrode layer 24 is a rectangle, but is not limited thereto, and may be a triangle, a polygon, a circle, an ellipse, or the like. The size of the islands of the base electrode layer 24 does not have to be constant.

[0017] The upper electrode layer 23 may be made of Au, Pt, Ag, Cu, or the like, with Au being preferred since it is less susceptible to the effects of oxidation and has excellent aging characteristics. The constituent material of the base electrode layer 24 is Cr, Ti, TiW, Ni, etc., with Cr being preferred since it enhances the adhesion of the electrode 20 .

[0018] Next, the relationship between the area ratio per unit area of ​​the base electrode layer 24 in the first region 21 and the sheet resistance ratio of the electrode 20 will be described with reference to FIG. 5 is a plot of the results of simulating the sheet resistance ratio of the electrode 20 based on the sheet resistance value of the electrode 20 at an area ratio of 100% per unit area of ​​the base electrode layer 24. The simulation was performed assuming that the base electrode layer 24 was made of Cr and had a film thickness of 7.5 nm, and the upper electrode layer 23 was made of Au and had a film thickness of 200 nm.

[0019] 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 in the base electrode layer 24 that diffuses into the Au of the upper electrode layer 23 decreases, and the sheet resistance value of the electrode 20 decreases. When 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. When the area ratio of the base electrode layer 24 is less than 10%, the sheet resistance ratio of the electrode 20 can be made smaller, but the adhesion of the electrode 20 to the substrate 30 decreases, and there is a risk of peeling off. Therefore, in this 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 electrode 33, is set to 10% or more and less than 50%.

[0020] Furthermore, by making the area ratio of the base electrode layer 24 per unit area of ​​the mount electrode 36 100%, the amount of Cr in the base electrode layer 24 that diffuses into the surface of the upper electrode layer 23 can be increased. In this case, by using a conductive adhesive that has good adhesion to Cr instead of the metal bumps 38, it is possible to further increase the adhesive bonding strength between the electrodes 20 and the substrate 30.

[0021] In this embodiment, a vibrator having a vibration piece 3 of a thickness-slide vibration system is described as an example, but the present invention is not limited to this, and a vibrator having a tuning-fork type vibration piece of a bending vibration system may be used. Also, an oscillator in which the vibration piece 3 and an oscillation circuit are housed in a package 2 may be used.

[0022] As described above, the vibrating piece 3 of this embodiment has the electrode 20 including the first region 21 in which the base electrode layer 24 is scattered like islands in a plan view 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 an increase in the sheet resistance value of the electrode 20 due to diffusion of the base electrode layer 24 can be suppressed, and deterioration of vibration characteristics can be suppressed. Therefore, the vibrating device 1 including the vibrating piece 3 of this embodiment has excellent reliability and vibration characteristics.

[0023] 2. Second embodiment Next, a vibrating element 3a included in a vibrating device 1a according to a second embodiment will be described with reference to Fig. 6 and Fig. 7. The vibrating device 1a of this embodiment is similar to the vibrating device 1 of the first embodiment, except that the configuration of the electrode 20a of the vibrating element 3a is different. The following description will focus on the differences from the first embodiment, and the description of the similar points will be omitted.

[0024] As shown in Figures 6 and 7, the vibrating piece 3a provided in the vibrating device 1a of this embodiment has the base electrode layer 24 scattered in an island-like manner, and the first region 21a, in which the area ratio of the base electrode layer 24 per unit area is 10% or more and less than 50%, is the region of the excitation electrode 33 and the extraction electrode 34, and the area ratio of the base electrode layer 24 per unit area in the region of the mount electrode 36 is 100%.

[0025] With this configuration, the sheet resistance in the region of the extraction electrode 34 can also be reduced, and the same effects as in the first embodiment can be obtained.

[0026] 3. Third embodiment Next, a vibrating element 3b included in a vibrating device 1b according to a third embodiment will be described with reference to Fig. 8 and Fig. 9. The vibrating device 1b of this embodiment is similar to the vibrating device 1 of the first embodiment, except that the configuration of the electrode 20b of the vibrating element 3b is different. The following description will focus on the differences from the first embodiment, and the description of the similar matters will be omitted.

[0027] As shown in Figures 8 and 9, the vibrating element 3b provided in the vibrating device 1b of this embodiment has a first region 21b in which the underlying electrode layer 24 is scattered in an island-like manner and the area ratio of the underlying electrode layer 24 per unit area is 10% or more and less than 50%, which is the region of the excitation electrode 33, the extraction electrode 34, and the mount electrode 36.

[0028] With this configuration, all electrode regions can be formed under the same conditions, which makes it easier to form the electrodes and provides the same effects as in the first embodiment.

[0029] 4. Fourth embodiment Next, a vibrating piece 3c included in a vibrating device 1c according to a fourth embodiment will be described with reference to Fig. 10 and Fig. 11. The vibrating device 1c of this embodiment is similar to the vibrating device 1 of the first embodiment, except for the configuration of the electrodes 20c of the vibrating piece 3c and the use of a conductive adhesive instead of the metal bumps 38. The following description will focus on the differences from the first embodiment, and will omit a description of similar matters.

[0030] As shown in Figures 10 and 11, the vibrating piece 3c provided in the vibrating device 1c of this embodiment has a first region 21c in which the underlying electrode layer 24 is scattered in an island-like manner and the area ratio of the underlying electrode layer 24 per unit area is 10% or more and less than 50%, which is the region of the excitation electrode 33 and the extraction electrode 34, and the underlying electrode layer 24 in the region of the mount electrode 36 which is the second region 22 is scattered in an island-like manner and the area ratio of the underlying electrode layer 24 per unit area is 50% or more.

[0031] With this configuration, the amount of Cr in the base electrode layer 24 in the mount electrode 36 that diffuses to the surface of the upper electrode layer 23 can be increased, ensuring adhesion with the conductive adhesive and reducing the sheet resistance in the areas of the excitation electrode 33 and the extraction electrode 34, thereby achieving the same effects as in the first embodiment. [Explanation of symbols]

[0032] 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...lid, 17...recess, 18...accommodation space, 19...bonding member, 20...electrode, 21...first region, 22...second region, 23...upper electrode layer, 24...underlying electrode layer, 30...substrate, 31...first surface, 32...second surface, 33...excitation electrode, 34...extraction electrode, 35...side electrode, 36...mount electrode, 38...metal bump.

Claims

1. A substrate made of quartz crystal; an electrode disposed on a surface of the substrate; the electrode includes an upper electrode layer and a base electrode layer disposed between the substrate and the upper electrode layer; the electrode includes a first region in which the base electrode layer is scattered like islands in a plan view and an area ratio of the base electrode layer per unit area is 10% or more and less than 50%; vibrating piece.

2. The material of the base electrode layer is Cr. The vibrator element according to claim 1 .

3. The material of the upper electrode layer is Au. The vibrator element according to claim 2 .

4. the electrodes include an excitation electrode, a mount electrode, and an extraction electrode connecting the excitation electrode and the mount electrode; The first region is included in at least the excitation electrode of the excitation electrode and the extraction electrode. The vibrator element according to claim 1 .

5. The first region is also included in the mount electrode. The vibrator element according to claim 4 .

6. the electrode includes a second region in which an area ratio of the base electrode layer per unit area is 50% or more, The second region is included in the mount electrode. The vibrator element according to claim 4 .

7. The vibrating element according to claim 4 , a package having a terminal; and a conductive adhesive that connects the mount electrode and the terminal. Vibration devices.

8. The vibrator element according to claim 6 , a package having a terminal; and a metal bump connecting the mount electrode and the terminal. Vibration devices.

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