Resonator element, resonator, and oscillator

Abstract

The invention provides a resonator element, a resonator, and an oscillator with high frequency and low CI value. The resonator element includes: a quartz substrate having a resonator portion including a resonator region and a support portion having a thickness larger than that of the resonator portion; and an excitation electrode disposed in the vibration region, the excitation electrode satisfying the following relationship: y < = 11.4 exp (-x / 174.8) + 1.8, where y [nm] is the surface roughness and x [MHz] is the oscillation frequency in the vibration region of the quartz substrate.

Description

Technical Field

[0001] The present invention relates to a vibration element, a vibrator and an oscillator. Background Art

[0002] Patent document 1 discloses a small piezoelectric vibration element that uses a fundamental wave to achieve a low CI value and suppresses nearby parasitic high frequencies. The vibration element comprises: a rectangular vibration portion; an L-shaped thick-walled portion formed integrally with the vibration portion; and a gap arranged in the thick-walled portion.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-7693

[0004] Communications equipment demands higher speeds and larger capacity, driving the need for higher frequencies in resonator components. However, with higher frequencies, CI values ​​tend to increase, increasingly failing to meet the required oscillator performance. Therefore, simply focusing on the configuration of the vibrating and thick-walled sections, as in the piezoelectric resonator element described in Patent Document 1, faces limitations in achieving higher frequencies or lower CI values. Summary of the Invention

[0005] The vibration element comprises: a quartz substrate having a vibration portion including a vibration region and a support portion having a thickness greater than that of the vibration portion; and an excitation electrode arranged in the vibration region, wherein when the surface roughness of the vibration region of the quartz substrate is y [nm] and the oscillation frequency is x [MHz], the following relationship is satisfied: y≤11.4exp(-x / 174.8)+1.8.

[0006] The vibrator includes: the above-mentioned vibration element; and a container that houses the vibration element.

[0007] An oscillator includes: the vibration element described above; an oscillation circuit for exciting the vibration element; and a container for housing the vibration element and the oscillation circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a perspective view showing the structure of the vibration element according to the first embodiment.

[0009] Figure 2 This is a diagram explaining the relationship between an AT-cut quartz substrate and the crystal axis of quartz.

[0010] Figure 3 yes Figure 1 A top view of the vibrating element is shown.

[0011] Figure 4 yes Figure 3 Cross-sectional view at line A1-A1 in FIG.

[0012] Figure 5 is a graph showing a relationship between an oscillation frequency and a surface roughness of a vibration region.

[0013] Figure 6 is a plan view showing a structure of a vibration element of the second embodiment.

[0014] Figure 7 is a cross-sectional view at A2-A2 line in Figure 6

[0015] Figure 8 is a plan view showing a structure of a vibration element of the third embodiment.

[0016] Figure 9 is a cross-sectional view at A3-A3 line in Figure 8

[0017] Figure 10 is a plan view showing a structure of a vibration element of the fourth embodiment.

[0018] Figure 11 is a cross-sectional view at A4-A4 line in Figure 10

[0019] Figure 12 is a plan view showing a structure of a vibration element of the fifth embodiment.

[0020] Figure 13 is a cross-sectional view at A5-A5 line in Figure 12

[0021] Figure 14 is a plan view showing a structure of a vibration element of the sixth embodiment.

[0022] Figure 15 is a cross-sectional view at A6-A6 line in Figure 14

[0023] Figure 16 is a plan view showing a structure of a vibrator of the seventh embodiment.

[0024] Figure 17 is a cross-sectional view at A7-A7 line in Figure 16

[0025] Figure 18 is a plan view showing a structure of an oscillator of the eighth embodiment.

[0026] Figure 19 is a cross-sectional view at A8-A8 line in Figure 18 Explanation of Reference Signs

[0027]

[0028] ​​​​​​​1, 1a, 1b, 1c, 1d, 1e: Vibration element; 2: Vibrator; 3: Oscillator; 10: Quartz substrate; 11: Vibration part; 12: Support part; 13: Vibration area; 14: One surface; 15: Other surface; 16: Connecting part; 17: Connecting part; 20: Container; 21: Cover; 22: Recessed part; 23: Storage space; 24: Inner bottom surface; 25: Base; 26: Lower surface; 27: Upper surface; 28: Inner end 29: External terminal; 31, 32: Excitation electrodes; 33, 34: Pad electrodes; 35, 36: Lead-out electrodes; 40: Container; 41: Cover; 42: Recess; 43: Accommodation space; 44: Inner bottom surface; 46: Lower surface; 47: Upper surface; 48: Internal terminal; 49: External terminal; 50, 51, 52: Joining parts; 60, 61: Bonding wires; 70: Oscillation circuit; 71: Circuit terminal; Y: Approximate curve. DETAILED DESCRIPTION

[0029] 1. First Implementation

[0030] Reference Figures 1-4 The vibration element 1 according to the first embodiment will be described.

[0031] In addition, for the sake of convenience, Figure 2 、 Figure 5 、 Figure 18 as well as Figure 19 In the following figures, the X-axis, Y'-axis, and Z'-axis are shown as three mutually perpendicular axes. Furthermore, the longitudinal direction of the vibration element 1 is referred to as the "X direction" along the X-axis, the thickness direction of the vibration element 1 is referred to as the "Y' direction" along the Y' axis, and the direction perpendicular to the X-axis and Y' axis is referred to as the "Z' direction" along the Z' axis. Furthermore, the arrow side of each axis is referred to as the "positive side," and the side opposite to the arrow is referred to as the "negative side."

[0032] like Figure 1 As shown, the vibration element 1 of this embodiment includes a quartz substrate 10 having a vibration portion 11 including a vibration region 13 and a support portion 12 having a thickness greater than that of the vibration portion 11 ; and excitation electrodes 31 and 32 arranged in the vibration region 13 .

[0033] The quartz substrate 10 is a plate-shaped substrate. Here, the quartz used as the material of the quartz substrate 10 belongs to the trigonal system, such as Figure 2As shown, the crystal axes X, Y, Z are perpendicular to each other. The X axis, Y axis, and Z axis are respectively referred to as the electric axis, the mechanical axis, and the optical axis. The quartz substrate 10 of the present embodiment is a "rotated Y-cut quartz substrate" cut along a plane after rotating the XZ plane around the X axis by a prescribed angle Θ, and for example, a substrate cut along a plane after rotating Θ = 35° 15' is referred to as an "AT-cut quartz substrate". By using such a quartz substrate 10, a vibration element 1 having excellent temperature characteristics is obtained.

[0034] However, as the quartz substrate 10, as long as it is possible to excite thickness shear vibration, it is not limited to an AT-cut quartz substrate, and for example, a BT-cut quartz substrate can also be used.

[0035] Further, hereinafter, the Y axis and Z axis rotated around the X axis in correspondence with the angle Θ are set as a Y' axis and a Z' axis. That is, the quartz substrate 10 has a thickness in the Y' direction and has an extension in the XZ' plane direction.

[0036] The quartz substrate 10 has an elongated shape with the X direction as the long side and the Z' direction as the short side when viewed from above. Further, the quartz substrate 10 has the negative X direction as the tip side and the positive X direction as the base side.

[0037] As shown in Figure 1 and Figure 3 , the quartz substrate 10 has a vibration portion 11 including a region in which vibration energy is enclosed, that is, a vibration region 13, and a support portion 12 integrated with the vibration portion 11 and having a thickness greater than that of the vibration portion 11.

[0038] The vibration portion 11 is biased toward the negative side of the X direction and the negative side of the Z' direction with respect to the center of the quartz substrate 10, and a part of the outer edge thereof is exposed from the support portion 12. That is, a part of the outer edge of the vibration portion 11 constitutes a part of the outer edge of the quartz substrate 10. When the vibration element 1 is viewed from above, the area of the vibration portion 11 is preferably 1 / 2 or less of the area of the quartz substrate 10. Thereby, the support portion 12 having high mechanical strength can be formed wide enough, and thus the rigidity of the vibration portion 11 can be sufficiently ensured.

[0039] The support portion 12 protrudes from the vibration portion 11 on the side of one face 14 of the vibration portion 11. Specifically, as shown in Figure 1 , Figure 3 and Figure 4 , the main face of the support portion 12 on the positive side of the Y' direction is provided to protrude toward the positive side of the Y' direction more than the main face of the vibration portion 11 on the positive side of the Y' direction, that is, the one face 14. On the other hand, the main face of the support portion 12 on the negative side of the Y' direction is provided on the same plane as the main face of the vibration portion 11 on the negative side of the Y' direction, that is, the other face 15.

[0040] The support portion 12 has a support portion 12 connected to the outer edge of the positive side in the X direction of the vibration portion 11 and a support portion 12 connected to the outer edge of the positive side in the Z' direction of the vibration portion 11. Thus, the support portion 12 has a configuration curved along the vibration portion 11 in plan view, and is substantially L-shaped. Thus, it is possible to reduce the mass of the tip side of the vibration element 1 while maintaining the rigidity of the vibration portion 11 of the vibration element 1. Also, it is possible to achieve miniaturization of the vibration element 1.

[0041] The support portion 12 has a connection portion 16 connected between the support portion 12 and the vibration portion 11, which is provided in connection with the outer edge of the positive side in the Z' direction of the vibration portion 11 and has an inclined portion in which the thickness gradually increases toward the positive Z' direction, and a connection portion 17 provided in connection with the outer edge of the positive side in the X direction of the vibration portion 11 and having an inclined portion in which the thickness gradually increases toward the positive X direction. In addition, the support portion 12 on the connection portion 17 side becomes a mounting portion, and is fixed to a container or the like using a conductive adhesive or the like.

[0042] A pair of excitation electrodes 31, 32, a pair of pad electrodes 33, 34, and a pair of lead electrodes 35, 36 are formed in the quartz substrate 10.

[0043] The excitation electrodes 31, 32 are disposed in the vibration region 13 of the vibration portion 11. The excitation electrode 31 is disposed on one face 14 of the vibration portion 11. On the other hand, the excitation electrode 32 is disposed on the other face 15 of the vibration portion 11 so as to oppose the excitation electrode 31. The excitation electrodes 31, 32 are each substantially rectangular with the X direction as the long side and the Z' direction as the short side.

[0044] The pad electrodes 33, 34 are disposed on the base end portion of the support portion 12 on the connection portion 17 side. The pad electrode 33 is disposed on the one face 14 side of the vibration portion 11. On the other hand, the pad electrode 34 is disposed on the other face 15 side of the vibration portion 11 so as to oppose the pad electrode 33.

[0045] The lead electrodes 35, 36 are disposed on the vibration portion 11 and the support portion 12. The lead electrode 35 electrically connects the excitation electrode 31 and the pad electrode 33. On the other hand, the lead electrode 36 electrically connects the excitation electrode 32 and the pad electrode 34. The lead electrodes 35, 36 are disposed so as not to overlap with each other across the quartz substrate 10. Thus, it is possible to suppress the electrostatic capacitance between the lead electrodes 35, 36.

[0046] Next, in order to achieve further high frequency and low CI value, reference is made to Figure 5 The relationship between the oscillation frequency of the vibration element 1 and the surface roughness of the vibration region 13 will be described.

[0047] Figure 5is a graph in which surface roughness of the vibration region 13 in which the CI value with respect to the oscillation frequency of the vibration element 1 satisfies a prescribed value is actually measured and plotted, and is a graph showing an approximate curve Y calculated by the least squares method according to three times of plotting.

[0048] In a case where the surface roughness in the vibration region 13 of the quartz substrate 10 is y [nm] and the oscillation frequency is x [MHz], the approximate curve Y satisfies the following relationship: y ≤ 11.4exp(-x / 174.8) + 1.8. In addition, the surface roughness in the vibration region 13 of the quartz substrate 10 is a root mean square height measured by a white light interferometer.

[0049] According to Figure 5 , the vibration element 1 having a low CI value can be obtained by making the surface roughness in the vibration region 13 be the value of the approximate curve Y at each oscillation frequency.

[0050] Further, when the surface roughness in the vibration region 13 is set to 6 nm or less, the vibration element 1 having a low CI value at an oscillation frequency of 174 MHz or less can be obtained.

[0051] Further, when the surface roughness in the vibration region 13 is set to 3 nm or less, the vibration element 1 having a low CI value at an oscillation frequency of 392 MHz or less can be obtained.

[0052] Further, when the surface roughness in the vibration region 13 is set to 2 nm or less, the vibration element 1 having a low CI value at an oscillation frequency of 700 MHz or less can be obtained.

[0053] That is, the vibration element 1 having a low CI value can be obtained by making the surface roughness in the vibration region 13 be the value of the approximate curve Y or less at each oscillation frequency.

[0054] As described above, the vibration element 1 of the present embodiment satisfies the following relationship: y ≤ 11.4exp(-x / 174.8) + 1.8 in a case where the surface roughness in the vibration region 13 of the quartz substrate 10 is y [nm] and the oscillation frequency is x [MHz], and thus can become a low CI value also at a high frequency. Therefore, the required performance of an oscillator for a communication device for high-speed and large-capacity communication can be satisfied.

[0055] 2. Second Embodiment

[0056] Next, the vibration element 1a of the second embodiment will be described with reference to Figure 6 and Figure 7 .

[0057] The vibration element 1a of the present embodiment is the same as the vibration element 1 of the first embodiment except for the configuration of the quartz substrate 10a. In addition, the same reference numerals are attached to the same matters and the description thereof is omitted, with the focus on the differences from the first embodiment.

[0058] As shown in FIG. 1A, the vibration element 1a has a quartz substrate 10a having a vibration portion 11 including a vibration region 13 and a support portion 12a having a larger thickness than the vibration portion 11, and drive electrodes 31, 32 disposed in the vibration region 13. Figure 6 Figure 7 As shown in FIG. 1A, the vibration element 1a has a quartz substrate 10a having a vibration portion 11 including a vibration region 13 and a support portion 12a having a larger thickness than the vibration portion 11, and drive electrodes 31, 32 disposed in the vibration region 13.

[0059] The support portion 12a protrudes from the vibration portion 11 on one face 14 side and also protrudes from the vibration portion 11 on the other face 15 side opposite to the one face 14. That is, the vibration portion 11 is formed by etching the vibration portion 11 from both the one face 14 and the other face 15, and thus the etching amount of the single face can be reduced and the vibration element 1a having a small plate thickness deviation of the vibration portion 11 can be obtained.

[0060] The support portion 12a has a connection portion 16a connected to the outer edge of the vibration portion 11 on the positive side of the Z' direction and having a slope portion in which the thickness gradually increases toward the positive Z' direction, a connection portion 17a connected to the outer edge of the vibration portion 11 on the positive side of the X direction and having a slope portion in which the thickness gradually increases toward the positive X direction, and a connection portion 18a connected to the outer edge of the vibration portion 11 on the negative side of the Z' direction and having a slope portion in which the thickness gradually increases toward the negative Z' direction.

[0061] The outer edges of the vibration portion 11 on the positive side of the X direction, the positive side of the Z' direction, and the negative side of the Z' direction are connected to the support portion 12a, and a part of the outer edge of the vibration portion 11, that is, the outer edge on the negative side of the X direction constitutes a part of the outer edge of the quartz substrate 10a. Thus, the rigidity of the vibration portion 11 of the vibration element 1a is further improved.

[0062] In the present embodiment, the support portion 12a is connected to the three outer edges of the vibration portion 11, but as in the first embodiment, the support portion 12a can be connected to the two outer edges of the vibration portion 11.

[0063] By adopting such a configuration, the vibration element 1a has a low CI value at a high frequency, the plate thickness deviation of the vibration portion 11 can be reduced, and the vibration element 1a having further improved rigidity of the vibration portion 11 can be obtained.

[0064] 3. Third Embodiment

[0065] Next, the third embodiment will be described with reference to​Figure 8 and Figure 9 The third embodiment of the vibration element 1b will be described.

[0066] The vibration element 1b of the present embodiment is the same as the vibration element 1 of the first embodiment except for the configuration of the quartz substrate 10b. Further, the description will be made focusing on the difference from the first embodiment described above, the same reference numerals are attached to the same matters and the description thereof is omitted.

[0067] As shown in Figs. 1 and 2, the vibration element 1b has a quartz substrate 10b having a vibration portion 11 including a vibration region 13 and a support portion 12b having a larger thickness than the vibration portion 11, and drive electrodes 31, 32 disposed in the vibration region 13. Figure 8 and Figure 9 As shown in Figs. 1 and 2, the vibration element 1b has a quartz substrate 10b having a vibration portion 11 including a vibration region 13 and a support portion 12b having a larger thickness than the vibration portion 11, and drive electrodes 31, 32 disposed in the vibration region 13.

[0068] The support portion 12b includes a first support portion 121 disposed along one outer edge of the vibration portion 11, i.e., the positive Z' side outer edge, and a second support portion 122 disposed along the other outer edge of the vibration portion 11 opposite to the one outer edge, i.e., the negative Z' side outer edge, the first support portion 121 protruding from the vibration portion 11 on the one face 14 side, and the second support portion 122 protruding from the vibration portion 11 on the other face 15 side opposite to the one face 14. That is, the support portion 12b is formed by etching from both faces toward the vibration portion 11, so that the etching amount of the single face can be reduced, and the vibration element 1b having a small plate thickness deviation of the vibration portion 11 can be obtained.

[0069] The first support portion 121 is connected to the vibration portion 11 by means of a connecting portion 16b provided in connection with the outer edge 111 of the vibration portion 11 on the positive Z' side and having a sloped portion in which the thickness gradually increases toward the positive Z' direction. Further, the support portion 12b is connected to the vibration portion 11 by means of a connecting portion 17b provided in connection with the outer edge of the vibration portion 11 on the positive X' side and having a sloped portion in which the thickness gradually increases toward the positive X' direction. The second support portion 122 is connected to the vibration portion 11 by means of a connecting portion 18b provided in connection with the outer edge 112 of the vibration portion 11 on the negative Z' side and having a sloped portion in which the thickness gradually increases toward the negative Z' direction. Thus, the vibration region 13 of the vibration portion 11 can be enlarged.

[0070] In the vibration portion 11, only a part of the outer edge of the vibration portion 11, i.e., the outer edge on the negative X' side, constitutes a part of the outer edge of the quartz substrate 10b. Thus, the rigidity of the vibration portion 11 of the vibration element 1b is further improved.

[0071] By adopting such a structure, the vibration element 1b has a low CI value at a high frequency, can reduce the plate thickness deviation of the vibration portion 11, can expand the vibration region 13 of the vibration portion 11, and can obtain a vibration element 1b further improved in rigidity of the vibration portion 11.

[0072] 4. Fourth Embodiment

[0073] Next, the vibration element 1c of the fourth embodiment will be described with reference to Figure 10 and Figure 11 The vibration element 1c of the fourth embodiment will be described.

[0074] The vibration element 1c of the present embodiment is the same as the vibration element 1 of the first embodiment except for the configuration of the quartz substrate 10c. Further, the description will be made focusing on the difference from the above-described first embodiment, the same reference numerals are attached to the same matters and the description thereof will be omitted.

[0075] As shown in Figure 10 and Figure 11 The vibration element 1c has a quartz substrate 10c having a vibration portion 11 including a vibration region 13 and a support portion 12c having a larger thickness than the vibration portion 11, and drive electrodes 31, 32 disposed in the vibration region 13.

[0076] The support portion 12c protrudes on the one face 14 side of the vibration portion 11.

[0077] Further, the support portion 12c has a connecting portion 16c connected to the outer edge of the vibration portion 11 on the positive side of the Z' direction, which is provided so as to have a slope portion in which the thickness gradually increases toward the positive Z' direction, a connecting portion 17c connected to the outer edge of the vibration portion 11 on the positive side of the X direction, which is provided so as to have a slope portion in which the thickness gradually increases toward the positive X direction, and a connecting portion 18c connected to the outer edge of the vibration portion 11 on the negative side of the X direction, which is provided so as to have a slope portion in which the thickness gradually increases toward the negative X direction.

[0078] The outer edge on the positive side of the Z' direction, the outer edge on the positive side of the X direction, and the outer edge on the negative side of the X direction of the vibration portion 11 are connected to the support portion 12c, and a part of the outer edge of the vibration portion 11, i.e., the outer edge on the negative side of the Z' direction constitutes a part of the outer edge of the quartz substrate 10c. Therefore, the rigidity of the vibration portion 11 of the vibration element 1c is further improved.

[0079] In the present embodiment, the vibration portion 11 is formed by etching from the one face 14 side, but as in the second and third embodiments, the vibration portion 11 can also be formed by etching from the other face 15 side at the same time.

[0080] By adopting such a structure, the vibration element 1c has a low CI value at a high frequency, and a vibration element 1c in which the rigidity of the vibration portion 11 is further improved can be obtained.

[0081] 5. Fifth Embodiment

[0082] Next, the vibration element 1d of the fifth embodiment will be described with reference to Figure 12 and Figure 13 The vibration element 1d of the fifth embodiment is the same as the vibration element 1 of the first embodiment except for the configuration of the quartz substrate 10d. Further, the same reference numerals are attached to the same matters and the description thereof will be omitted, with the focus on the differences from the first embodiment described above.

[0083] The vibration element 1d of the fifth embodiment is the same as the vibration element 1 of the first embodiment except for the configuration of the quartz substrate 10d. Further, the same reference numerals are attached to the same matters and the description thereof will be omitted, with the focus on the differences from the first embodiment described above.

[0084] As shown in Figure 12 and Figure 13 , the vibration element 1d has a quartz substrate 10d having a vibration portion 11 including a vibration region 13 and a support portion 12d having a larger thickness than the vibration portion 11, and drive electrodes 31, 32 disposed in the vibration region 13.

[0085] The support portion 12d protrudes on the one face 14 side of the vibration portion 11.

[0086] Further, the support portion 12d has a connecting portion 17d connected between the support portion 12d and the vibration portion 11, the connecting portion 17d being connected to the outer edge on the positive X direction side of the vibration portion 11, and having an inclined portion in which the thickness gradually increases toward the positive X direction.

[0087] The outer edge on the positive X direction side of the vibration portion 11 is connected to the support portion 12d, and a part of the outer edge of the vibration portion 11, i.e., the outer edge on the positive Z' direction side, the outer edge on the negative X direction side, and the outer edge on the negative Z' direction side constitute a part of the outer edge of the quartz substrate 10d. Thus, the vibration region 13 of the vibration portion 11 can be enlarged.

[0088] In the present embodiment, the vibration portion 11 is formed by etching from the one face 14 side, but as in the second and third embodiments, the vibration portion 11 can be formed by simultaneously etching from the other face 15 side.

[0089] By adopting such a structure, the vibration element 1d has a low CI value at a high frequency, and a vibration element 1d in which the vibration region 13 of the vibration portion 11 is large can be obtained.

[0090] 6. Sixth Embodiment

[0091] Next, the vibration element 1d of the fifth embodiment will be described with reference to Figure 14 and Figure 15 The vibration element 1d of the fifth embodiment is the same as the vibration element 1 of the first embodiment except for the configuration of the quartz substrate 10d. Further, the same reference numerals are attached to the same matters and the description thereof will be omitted, with the focus on the differences from the first embodiment described above.The sixth embodiment of the vibration element 1e will be described.

[0092] The vibration element 1e of the present embodiment is the same as the vibration element 1 of the first embodiment except for the configuration of the quartz substrate 10e. Further, the description will be made focusing on the difference from the first embodiment described above, the same reference numerals are attached to the same matters and the description thereof will be omitted.

[0093] As shown in Figure 14 and Figure 15 , the vibration element 1e has a quartz substrate 10e having a vibration portion 11 including a vibration region 13 and a support portion 12e having a larger thickness than the vibration portion 11, and drive electrodes 31, 32 disposed in the vibration region 13.

[0094] The support portion 12e protrudes on the one face 14 side of the vibration portion 11.

[0095] Further, the support portion 12e surrounds the vibration portion 11 when viewed from the top. That is, the support portion 12e has a connection portion 16e disposed in connection with the outer edge of the vibration portion 11 on the positive side of the Z' direction, having a slope portion in which the thickness gradually increases toward the positive Z' direction, a connection portion 17e disposed in connection with the outer edge of the vibration portion 11 on the positive side of the X direction, having a slope portion in which the thickness gradually increases toward the positive X direction, a connection portion 18e disposed in connection with the outer edge of the vibration portion 11 on the negative side of the X direction, having a slope portion in which the thickness gradually increases toward the negative X direction, and a connection portion 19e disposed in connection with the outer edge of the vibration portion 11 on the negative side of the Z' direction, having a slope portion in which the thickness gradually increases toward the negative Z' direction. Thus, the rigidity of the vibration portion 11 of the vibration element 1e is further improved.

[0096] In the present embodiment, the vibration portion 11 is formed by etching from the one face 14 side, but as in the second and third embodiments, the vibration portion 11 can be formed by etching from the other face 15 side at the same time.

[0097] By adopting such a configuration, the vibration element 1e has a low CI value at a high frequency, and a vibration element 1e in which the rigidity of the vibration portion 11 is further improved can be obtained.

[0098] 7. Seventh Embodiment

[0099] Next, the vibrator 2 of the seventh embodiment will be described with reference to Figure 16 and Figure 17 . In the present description, the vibrator 2 having the vibration element 1 described above is exemplified as an example. Further, in the following description, the same reference numerals are attached to the same matters as those of the first to sixth embodiments and the description thereof will be omitted. Figure 16In the present embodiment, in order to facilitate explanation of the internal structure of the vibrator 2, a state in which the cover 21 is removed is illustrated.

[0100] As shown in FIG. 1, the vibrator 2 has the vibration element 1, the container 20 that houses the vibration element 1, and the cover 21 that forms a housing space 23 with the container 20. Figure 16 Figure 17 As shown in FIG. 1, the vibrator 2 has the vibration element 1, the container 20 that houses the vibration element 1, and the cover 21 that forms a housing space 23 with the container 20.

[0101] The container 20 has a recess 22 that is open to the cover 21 side, and the cover 21 is joined to the upper surface 27 so as to close the opening of the recess 22. By closing the recess 22 of the container 20 with the cover 21, the housing space 23 that houses the vibration element 1 is formed. The housing space 23 can be in a reduced pressure or vacuum state, or can be sealed with an inert gas such as nitrogen (Ni), helium (He), or argon (Ar).

[0102] As the material that constitutes the container 20, various ceramics such as alumina can be used without particular limitation. In addition, as the material that constitutes the cover 21, a member having a linear expansion coefficient that is similar to that of the material that constitutes the container 20 can be used without particular limitation. In addition, the joining of the container 20 and the cover 21 is not particularly limited, and for example, the joining can be performed via an adhesive, or the joining can be performed by seam welding or the like.

[0103] An internal terminal 28 is formed on the inner bottom surface 24 of the container 20, and the internal terminal 28 is formed on a pedestal portion 25 that protrudes from the inner bottom surface 24 toward the cover 21. In addition, a plurality of external terminals 29 are formed on the lower surface 26 of the container 20. The internal terminal 28 on the inner bottom surface 24 is electrically connected to the external terminal 29 via a through electrode that is not shown and is formed in the container 20, and the internal terminal 28 on the pedestal portion 25 is electrically connected to the external terminal 29 via a through electrode that is not shown and is formed in the container 20.

[0104] The vibration element 1 housed in the housing space 23 has one face 14 of the vibration portion 11 facing the inner bottom surface 24 of the container 20, and is fixed to the container 20 at the support portion 12 by a joining member 50 that is a conductive adhesive. The joining member 50 is disposed in contact with the internal terminal 28 and the pad electrode 33. Thus, the internal terminal 28 and the pad electrode 33 are electrically connected via the joining member 50. By supporting the vibration element 1 at one or a point using the joining member 50, for example, stress that is generated in the vibration element 1 due to a difference in thermal expansion rate between the container 20 and the quartz substrate 10 can be suppressed.

[0105] ​The pad electrode 34 of the vibration element 1 is electrically connected to the internal terminal 28 via the bonding wire 60. As described above, the pad electrode 34 is disposed in opposition to the pad electrode 33, and thus is located directly above the joining member 50 in a state where the vibration element 1 is fixed to the container 20. Therefore, leakage of ultrasonic vibrations applied to the pad electrode 34 at the time of wire bonding can be suppressed, and connection of the bonding wire 60 to the pad electrode 34 can be performed more reliably.

[0106] By adopting such a structure, the vibrator 2 is provided with the vibration element 1 having a low CI value at a high frequency, and thus a vibrator 2 having a high frequency and a low CI value can be obtained.

[0107] Further, in the seventh embodiment, various ceramics are exemplified as the material of the container 20 and the lid 21, but the material is not limited thereto, and a semiconductor substrate can also be used.

[0108] 8. Eighth Embodiment

[0109] Next, the eighth embodiment will be described with reference to Figure 18 and Figure 19 The oscillator 3 of the eighth embodiment will be described. In the present description, an oscillator 3 provided with the vibrator 2 having the vibration element 1 described above is exemplified as an example. In Figure 18 , in order to facilitate description of the internal structure of the oscillator 3, a state where the lid 41 is removed is illustrated. Further, in Figure 19 , the cross-sectional configuration of the vibrator 2 is described in the above Figure 17 , and thus illustration thereof is omitted.

[0110] As illustrated in Figure 18 and Figure 19 , the oscillator 3 has: the vibrator 2 having the vibration element 1; an oscillation circuit 70 that excites the vibration element 1; a container 40 that houses the vibrator 2 and the oscillation circuit 70; and a lid 41 that forms a housing space 43 with the container 40.

[0111] The container 40 has a recessed portion 42 that is open to the lid 41 side, and the lid 41 that closes the opening of the recessed portion 42 is joined to the upper surface 47. By closing the recessed portion 42 of the container 40 with the lid 41, the housing space 43 that houses the vibrator 2 and the oscillation circuit 70 is formed.

[0112] As the material of the container 40, various ceramics such as alumina can be used. Further, as the material of the lid 41, there is no particular limitation. Further, the joining of the container 40 and the lid 41 is not particularly limited, and for example, the joining can be performed via an adhesive, or the joining can be performed by seam welding or the like.

[0113] A plurality of internal terminals 48 are formed on the inner bottom surface 44 of the container 40. In addition, a plurality of external terminals 49 are formed on the lower surface 46 of the container 40. Of the internal terminals 48 on the inner bottom surface 44, the internal terminals 48 disposed around the oscillation circuit 70 in a plan view are electrically connected to the external terminals 49 via a through electrode and a wiring not shown formed in the container 40. In addition, the internal terminals 48 disposed in positions overlapping the vibrator 2 in a plan view are electrically connected to the internal terminals 48 disposed around the oscillation circuit 70 via a wiring not shown.

[0114] The vibrator 2 housed in the housing space 43 is fixed to the container 40 at the external terminals 29 by a joining member 51 such as a conductive adhesive or solder. The external terminals 29 are electrically connected to the internal terminals 48 via the joining member 51.

[0115] The oscillation circuit 70 housed in the housing space 43 is fixed to the container 40 by a joining member 52 such as an adhesive. A plurality of circuit terminals 71 are provided on a side of the oscillation circuit 70 facing the lid 41, and the circuit terminals 71 are electrically connected to the internal terminals 48 disposed around the oscillation circuit 70 via the bonding wires 61. Some of the circuit terminals 71 are electrically connected to the external terminals 29 of the vibrator 2 via the internal terminals 48, and thus the vibration element 1 can be excited. In addition, some of the circuit terminals 71 are electrically connected to the external terminals 49 via the internal terminals 48, and thus power can be input from the external terminals 49, and an oscillation frequency output from the oscillation circuit 70 can be output from the external terminals 49.

[0116] With this configuration, the oscillator 3 has the vibration element 1 having a high frequency and a low CI value, and thus an oscillator 3 having a high frequency and excellent oscillation characteristics can be obtained.

[0117] In addition, in the eighth embodiment, the vibrator 2 housing the vibration element 1 in the container 20 is fixed to the container 40, but a configuration in which the vibration element 1 itself is mounted to the container 40 can also be employed. In addition, although not shown, as the container 40, a semiconductor substrate on which the oscillation circuit 70 is formed can also be used. By mounting the vibration element 1 on this semiconductor substrate, a space for the oscillation circuit 70 housed in the housing space 43 is not required, and the oscillator 3 can be made smaller.

Claims

1. A vibration element, comprising: a quartz substrate having a vibration portion including a vibration region and a support portion having a thickness greater than the vibration portion; and an excitation electrode disposed in the vibration region, when a surface roughness in the vibration region of the quartz substrate is y [nm] and an oscillation frequency is x [MHz], a relationship y < 11.4 exp(-x / 174.8) + 1.8 is satisfied.

2. The vibration element according to claim 1, wherein the surface roughness is 6 nm or less and the oscillation frequency is 174 MHz or less.

3. The vibration element according to claim 1, wherein the surface roughness is 3 nm or less and the oscillation frequency is 392 MHz or less.

4. The vibration element according to claim 1, wherein the surface roughness is 2 nm or less and the oscillation frequency is 700 MHz or less.

5. The vibration element according to any one of claims 1 to 4, wherein the support portion protrudes from the vibration portion on one face side of the vibration portion.

6. The vibration element according to claim 5, wherein the support portion also protrudes from the vibration portion on the other face side opposite to the one face.

7. The vibration element according to any one of claims 1 to 4, wherein the support portion includes: a first support portion disposed along one outer edge of the vibration portion; and a second support portion disposed along the other outer edge opposite to the one outer edge of the vibration portion with respect to the vibration portion, the first support portion protrudes from the vibration portion on one face side of the vibration portion, and the second support portion protrudes from the vibration portion on the other face side opposite to the one face.

8. The vibration element according to any one of claims 1 to 4, wherein a part of an outer edge of the vibration portion constitutes a part of an outer edge of the quartz substrate.

9. The vibration element according to any one of claims 1 to 4, wherein the support portion surrounds the vibration portion in a plan view.

10. An oscillator, comprising: the vibration element according to any one of claims 1 to 4; and a container that houses the vibration element.

11. An oscillator, comprising: the vibration element according to any one of claims 1 to 4; an oscillation circuit that excites the vibration element; and a container that houses the vibration element and the oscillation circuit. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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