JP2013098841A - Piezoelectric vibrator, and oscillator including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small piezoelectric vibrator for obtaining a frequency signal stable over a wide temperature range, and an oscillator including the piezoelectric vibrator.SOLUTION: Vibration units 11 and 21 are provided for a common piezoelectric plate 1, and a frame-like body 31 is disposed surrounding these vibration units 11 and 21. First and second support units 12 and 22 for supporting the vibration units 11 and 21, respectively relative to the frame-like body 31 are provided for the piezoelectric plate 1. The frame-like body 31 is provided with electrode pads 15 and 25 connected to excitation electrodes 13 and 23 of the vibration units 11 and 21, respectively. Between these vibration units 11 and 21 is provided an elastic boundary region 32 formed by twin crystallization of the piezoelectric plate 1, for example, thereby suppressing the propagation of the vibration of the piezoelectric plate 1. Further, the elastic boundary region 32 is provided for the first support unit 12 and the second support unit 22.

Description

  The present invention relates to a piezoelectric vibrator in which excitation electrodes are formed so as to sandwich a piezoelectric plate from the thickness direction, and an oscillator including the piezoelectric vibrator.

  For example, a crystal (piezoelectric) vibrator in which excitation electrodes are formed on both upper and lower surfaces of a piezoelectric plate made of quartz or the like is widely used in an oscillator such as a TCXO (Temperature Compensated Crystal Oscillator) as a reference frequency source that outputs a stable frequency signal. Has been. This TCXO has a temperature compensation circuit using a temperature sensitive element, and has an advantage that a stable frequency signal can be obtained over a wide temperature range, and that it is small and lightweight. As a TCXO capable of obtaining a more stable frequency signal, for example, as described in Patent Document 1, two vibrators are formed on a common piezoelectric plate, and one of these vibrators is used as a temperature sensor. The structure to do is known.

By the way, as electronic devices are further reduced in size, the quartz resonator is also required to be reduced in size, and as described in Patent Document 2, for example, vibration supported by an outer frame in a cantilever manner or a both-end manner. A method of manufacturing a child by a photolithography method is known.
However, these Patent Documents 1 and 2 or Patent Documents 3 to 12 specifically describe a technique for forming a TCXO using a photolithography method and an extraction electrode for inputting / outputting an electric signal to / from the TCXO. Not listed.

JP 2006-33195 A JP 7-212171 A JP 53-3179 JP 2004-146965 A JP2008-22378 JP 2011-35546 A JP2011-41113A JP2003-23339 JP-A-5-160659 JP 61-238116 A JP 61-13809 JP 2001-144578 A

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a small piezoelectric vibrator for obtaining a stable frequency signal over a wide temperature range and an oscillator including the piezoelectric vibrator. There is to do.

The piezoelectric vibrator of the present invention is
A first vibration unit and a second vibration unit configured to be provided with a pair of excitation electrodes on both sides of each of the left and right regions of the piezoelectric plate and having different resonance frequencies;
A frame-like body formed on the piezoelectric plate so as to surround the first vibrating portion and the second vibrating portion via a gap region;
From the left part of the frame-like body, the first support part extending toward the first vibration part to support the first vibration part, and from the right part of the frame-like body, the second part A second support portion extending toward the second vibration portion to support the vibration portion;
A first lead electrode formed on the first support part and connected to the excitation electrode of the first vibration part, and an excitation of the second vibration part formed on the second support part. A second extraction electrode connected to the electrode;
A first electrode pad and a second electrode pad provided on the frame-like body and connected to the first extraction electrode and the second extraction electrode, respectively;
Between the first vibrating part and the second vibrating part, the first supporting part and the second supporting part are formed in at least one place for suppressing propagation of vibration of the piezoelectric plate. And a boundary region.

  One electrode pad of the first electrode pad and the second electrode pad is for suppressing stress from being transmitted through the electrode pad to one vibrating portion connected to the electrode pad. You may arrange | position in the position which approached the other vibration part side on the said frame-like body.

The piezoelectric vibrator of the present invention is
A first vibration unit and a second vibration unit configured to be provided with a pair of excitation electrodes on both sides of each of the left and right regions of the piezoelectric plate and having different resonance frequencies;
A frame-like body formed on the piezoelectric plate so as to surround the first vibrating portion and the second vibrating portion via a gap region;
In order to support the first vibration part and the second vibration part, respectively, a first support part and a first support part extending from the frame body toward the first vibration part and the second vibration part, respectively. Two support parts;
A first lead electrode formed on the first support part and connected to the excitation electrode of the first vibration part, and an excitation of the second vibration part formed on the second support part. A second extraction electrode connected to the electrode;
A first electrode pad and a second electrode pad provided on the frame-like body and connected to the first lead electrode and the second lead electrode, respectively, are provided.

The oscillator of the present invention is
The previously described piezoelectric vibrator,
A first oscillation circuit connected to the first electrode pad;
A second oscillation circuit connected to the second electrode pad to use the second vibrating section as a temperature sensor;
And a signal output unit for obtaining a set frequency signal based on respective output signals of the first oscillation circuit and the second oscillation circuit.

  In the present invention, a first vibrating portion and a second vibrating portion are provided on a common piezoelectric plate, and a frame-like body surrounding the first vibrating portion and the second vibrating portion is disposed. On the other hand, a support portion for supporting the first vibrating portion and the second vibrating portion is provided on the piezoelectric plate. Therefore, a small piezoelectric vibrator for obtaining a stable frequency signal over a wide temperature range can be configured. Further, by providing support portions for supporting the first vibrating portion and the second vibrating portion on the left side portion of the frame-like body and the right side portion of the frame-like body, a piezoelectric vibrator having excellent mechanical strength can be obtained. Can be obtained. In addition, since the electrode pads connected to the excitation electrodes of the first vibrating portion and the second vibrating portion are provided in the frame-like body, mechanical stress from the electrode pad side, external of the piezoelectric vibrator, It is possible to suppress the expansion and contraction of the electrode pad due to the temperature change from being transmitted to each vibration part. Furthermore, by providing a boundary region for suppressing the propagation of the vibration of the piezoelectric plate between the first vibrating portion and the second vibrating portion, mutual interference between these vibrating portions can be suppressed. . In addition, since a boundary region is provided in at least one of the first support part and the second support part, leakage of vibration energy from the vibration part to the support part can be suppressed, so that a stable output signal can be obtained. Can do.

It is a perspective view which shows an example of the crystal oscillator of this invention. It is a top view which shows the surface side of the said crystal oscillator. It is a top view which shows the back surface side of the said crystal oscillator. It is a longitudinal cross-sectional view which shows the said crystal oscillator. It is a longitudinal cross-sectional view which shows a mode that the elastic boundary area | region in the said crystal oscillator is formed. It is a schematic diagram which shows the frequency characteristic of the said crystal oscillator. It is a schematic diagram which shows the frequency temperature characteristic of the said crystal oscillator. It is a circuit diagram which shows the oscillator provided with the said crystal oscillator. It is a longitudinal cross-sectional view which shows the other example of the said crystal oscillator. It is a longitudinal cross-sectional view which shows the other example of the said crystal oscillator. It is a longitudinal cross-sectional view which shows the other example of the said crystal oscillator. It is a longitudinal cross-sectional view which shows the other example of the said crystal oscillator. It is a longitudinal cross-sectional view which shows the other example of the said crystal oscillator. It is a longitudinal cross-sectional view which shows the other example of the said crystal oscillator. It is a top view which shows the other example of the said crystal oscillator. It is a top view which shows the other example of the said crystal oscillator. It is a top view which shows the other example of the said crystal oscillator.

  A crystal resonator as an example of an embodiment of a piezoelectric resonator of the present invention will be described with reference to FIGS. First, the outline of the crystal resonator will be described. As shown in FIG. 1, the crystal resonator includes two vibrating portions 11 arranged so as to face each other on a common piezoelectric plate 1 made of, for example, crystal. 21 is provided. The piezoelectric plate 1 is provided with a frame-like body 31 disposed so as to surround the vibrating portions 11 and 21 through a gap region when viewed in a plane, and the vibrating portions 11 and 21 are supported respectively. It is supported by the frame-like body 31 via the parts 12 and 22. In this example, the piezoelectric plate 1 is composed of an AT cut plate that is cut so that the longitudinal direction (X direction in FIG. 2) is the X axis of the crystal axis. In FIG. 1, reference numerals 2 and 3 denote a substantially box-shaped exterior body whose upper side opens to accommodate a crystal resonator, and a lid body that covers the upper surface of the exterior body, each of which is made of ceramics such as alumina (Al2O3). In addition, they are sealed together by, for example, direct bonding. Further, reference numeral 4 in FIG. 1 denotes an input / output electrode formed on the floor surface of the exterior body 2, and an electric signal is input / output to / from the crystal resonator via the input / output electrode 4. In FIG. 1, a part of the lid 3 is cut away.

  The direction in which the vibrating portions 11 and 21 are arranged is referred to as a left-right direction (X direction in FIG. 2), and “first” and “second” are attached to the left vibrating portion 11 and the right vibrating portion 21, respectively. The first vibrating portion 11 includes a first support portion 12 that extends in parallel to each other from a portion (left side portion) on the left side of the first vibrating portion 11 toward the first vibrating portion 11 in the frame-shaped body 31. 12 is supported. In addition, the second vibrating portion 21 is a second support that extends in parallel to each other from a portion (right side portion) on the right side of the second vibrating portion 21 in the frame-shaped body 31 toward the second vibrating portion 21. Supported by the portions 22 and 22. And the right end part of the 1st vibration part 11 and the left end part of the 2nd vibration part 21 are mutually connected. Therefore, the configuration including the vibrating parts 11 and 21 is supported by the frame-like body 31 with both left and right sides via the support parts 12 and 22.

  An elastic boundary region 32 for suppressing the vibration of the piezoelectric plate 1 from propagating through the region is formed in a region between the vibrating parts 11 and 21. In this example, the elastic boundary region 32 is formed by twinning the piezoelectric plate 1. Specifically, the elastic boundary region 32 is formed by, for example, irradiating and heating the piezoelectric plate 1 with laser light so that the piezoelectric plate 1 has a temperature equal to or higher than the α-β transition point of the crystal. It is formed by reversing the axis, that is, the X axis, and is formed across the longitudinal direction (Y direction in FIG. 2) and the thickness direction of the piezoelectric plate 1 as shown in FIGS. .

  That is, the elastic boundary region 32 is a region in which the piezoelectric plate 1 is altered so that the physical properties (resonance frequency) of the vibrating portions 11 and 21 are different from those of the piezoelectric plate 1. The vibration of the piezoelectric plate 1 is difficult to propagate through the elastic boundary region 32. Specifically, for example, vibration generated in the first vibrating section 11 tends to go to the second vibrating section 21 via the elastic boundary region 32, but the resonance frequency of the elastic boundary region 32 is the first. Therefore, the vibration is attenuated in the elastic boundary region 32, and the transmission to the second vibrating portion 21 is hindered. Similarly, the vibration generated in the second vibrating portion 21 is inhibited from propagating to the first vibrating portion 11 by the elastic boundary region 32. In FIG. 1, the elastic boundary region 32 is omitted.

  The elastic boundary region 32 is also formed in the support portions 12 and 22 between the vibrating portions 11 and 21 and the frame-like body 31 as shown in FIGS. Therefore, the vibration energy of each of the vibration parts 11 and 21 is suppressed from leaking to the frame body 31 via the support parts 12 and 22. Therefore, it can be said that the energy generated based on the vibration of the piezoelectric plate 1 is confined in each of the vibration portions 11 and 21.

  Then, the 1st vibration part 11 among these vibration parts 11 and 21 is demonstrated. On the upper surface side and the lower surface side of the first vibrating section 11, a pair of excitation electrodes formed in a rectangular shape so as to have the same film thickness, for example, about 0.1 μm, so as to sandwich the piezoelectric plate 1 from the thickness direction. 13a and 13b are arranged. The excitation electrode 13 a on the upper surface (front surface) side of the piezoelectric plate 1 includes the upper surface of the first support portion 12 on the near side and the side surface of the first support portion 12 of the two first support portions 12 and 12. One end side of the first extraction electrode 14 extending toward the lower surface (rear surface) side of the piezoelectric plate 1 is connected. As shown in FIG. 3, the other end side of the first lead electrode 14 extends toward the corner of the frame body 31 on the lower surface of the frame body 31 to form the first electrode pad 15. ing. In this embodiment, when the piezoelectric plate 1 is viewed in a plane (front side, FIG. 2), the front-rear direction is referred to as the front side and the back side.

  On the lower side of the first electrode pad 15, a bump made of a conductive material (in order to electrically connect the input / output electrode 4 formed on the floor surface of the exterior body 2 and the first electrode pad 15 ( A conductive adhesive 16 is formed. As shown in FIG. 4, an electrode 5 is formed on the lower surface of the exterior body 2 below the bump 16, and through a through wiring 6 provided so as to penetrate the lid body 3 in the vertical direction. Thus, an electric signal is input / output from the input / output electrode 4 to the first vibrating section 11.

  As shown in FIGS. 2 and 3, the excitation electrode 13 b on the back surface side of the first vibrating portion 11 is an extraction electrode formed on the back surface side of the back support portion 12 of the two support portions 12 and 12. One end side of the lead electrode 14 is connected, and the other end side of the lead electrode 14 extends from the back side of the frame-like body 31 toward the back side to form a first electrode pad 15. Similarly, the first electrode pad 15 is connected to the input / output electrode 4 via the bump 16 and the through wiring 6. Accordingly, the elastic boundary regions 32 described above are located between the first vibrating portion 11 and the first electrode pads 15 and 15, respectively.

  The second vibration part 21 is arranged so as to be point-symmetrical via the center position of the elastic boundary region 32 in the elastic boundary region 32 between the vibration parts 11 and 21 when viewed in a plane. That is, a pair of excitation electrodes 23 a and 23 b formed to have the same film thickness are disposed on the upper surface side and the lower surface side of the second vibrating portion 21. The film thicknesses of the excitation electrodes 23a and 23b are different from the excitation electrodes 13a and 13b described above in order to make the resonance frequency of the first vibration unit 11 and the resonance frequency of the second vibration unit 21 different from each other. Different dimensions, for example, about 0.3 μm.

  The excitation electrode 23 a on the upper surface side of the second vibration part 21 is connected to one end side of the extraction electrode 24 formed on the upper surface side of the support part 22 on the back side among the two support parts 22 and 22. The other end side of the lead electrode 24 extends to the right side in FIG. 2 and wraps around the lower surface side of the piezoelectric plate 1 to form a second electrode pad 25 at the corner of the frame 31. As shown in FIG. 4, the second electrode pad 25 is connected to the input / output electrode 4 on the lower side of the exterior body 2 through the bump 26, the electrode 5, and the through wiring 6.

  One end side of an extraction electrode 24 formed on the lower surface side of the support portion 22 on the front side of the two support portions 22, 22 is connected to the excitation electrode 23 b on the back surface side of the second vibration portion 21. The other end side of the extraction electrode 24 extends from the back side of the frame-shaped body 31 toward the front side to form a second electrode pad 25. The second electrode pad 25 is also connected to the input / output electrode 4 on the lower surface side of the exterior body 2 through the bump 26, the electrode 5, and the through wiring 6. Accordingly, the elastic boundary region 32 is located between the second vibrating part 21 and the second electrode pads 25 and 25 in the second vibrating part 21 as well. In FIG. 4, the thickness of the excitation electrodes 13 and 23 is exaggerated and drawn greatly.

  Next, a method for manufacturing the crystal resonator will be briefly described. First, the frame 31 and the vibrating portion 11 are formed on a wafer made of quartz crystal whose thickness is cut to about 100 μm and whose upper and lower surfaces are polished by, for example, photolithography using a resist mask and wet etching. , 21, a region between the frame-shaped body 31 and the support parts 12 and 22, and a region between the support parts 12 and 12 (22 and 22). Next, as already described, the elastic boundary region 32 is formed by partially heating the quartz wafer using, for example, laser light.

  Subsequently, excitation electrodes 13a, 13b, 23a, and 23b are formed on the upper and lower surfaces of the quartz wafer. Specifically, a resist mask patterned so as to open the areas where the excitation electrodes 13a and 13b are formed and cover the areas other than the areas is formed on the quartz wafer, and for example, sputtering or electroless is applied to the wafer. A metal film made of, for example, gold (Au) is formed by plating or the like. Next, the quartz wafer is immersed in, for example, an organic solvent or an alkaline aqueous solution, and the surplus metal film formed on the resist mask is removed together with the resist mask, thereby forming the excitation electrodes 13a and 13b. Subsequently, a resist mask patterned so as to open the regions where the excitation electrodes 23a and 23b are formed and to cover the regions other than the regions is formed on the quartz wafer, and the excitation electrodes 23a and 23b are formed in the same manner as the previous method. Form. Thereafter, the extraction electrodes 14 and 24 and the electrode pads 15 and 25 are formed by the same method, and then the piezoelectric plate 1 is separated into pieces by, for example, dicing. The size of the piezoelectric plate 1 when viewed in a plane is, for example, about 1650 μm × 3100 μm.

  The bumps 16 and 26 are disposed inside the exterior body 2 in which the input / output electrodes 4, the electrodes 5, and the through wiring 6 are formed, and the piezoelectric plate 1 is accommodated above the bumps 16 and 26. Next, the bumps 16 and 26 are melted by, for example, laser light irradiation, and the input / output electrode 4 and the crystal resonator (excitation electrodes 13 and 23) are electrically connected. Subsequently, the opening of the exterior body 2 is hermetically closed using the lid 3 in a vacuum atmosphere, and the exterior body 2 and the lid 3 are pressed against each other while being heated. And are joined directly.

  Accordingly, since the film thickness of the excitation electrodes 13a and 13b and the film thickness of the excitation electrodes 23a and 23b are shifted from each other, for example, as shown in FIG. 6, the resonance frequency and the second vibration of the first vibration unit 11 are obtained. The resonance frequency of the part 21 is different from each other. In addition, since the two vibrating portions 11 and 21 are formed on the common piezoelectric plate 1, the temperature of the atmosphere in which the vibrating portions 11 and 21 are placed is almost the same. Therefore, as shown in FIG. 7, the temperature characteristics (the degree to which the resonance frequency changes with respect to the temperature change) of the vibrating parts 11 and 21 are also aligned with each other. 6 and 7 schematically show the characteristics of the vibrating portions 11 and 21.

Next, an example of an oscillator including the crystal resonator described above will be described with reference to FIG. 8 taking the above-described TCXO as an example. This TCXO is a circuit for outputting a signal of the set frequency f _{0 to} the outside, and outputs this set frequency f ₀ without depending on the temperature change outside the TCXO or suppressing the influence of the external temperature change. It is configured to be able to. The set frequency f ₀ is an output frequency obtained when the reference voltage V ₀ is applied to the first oscillation circuit 17 at the reference temperature T _0, for example, 29 ° C.

A first oscillation circuit 17 is connected to the first vibration part 11 via electrode pads 15 and 15, and the second vibration part 21 is similarly connected to the first vibration part 11 via electrode pads 25 and 25. A second oscillation circuit 27 for using the second vibration unit 21 as a temperature sensor is connected. The temperature of the crystal unit is estimated between the oscillation circuits 17 and 27 based on the temperature compensation frequency signal input from the second oscillation circuit 27, and the first oscillation circuit 17 is connected to the temperature at this temperature. Thus, a control voltage supply unit 41 for calculating a control voltage V _c (V _c = V ₀ −ΔV) at which the set frequency f ₀ is obtained is provided as a signal output unit. 8 of 42 is an input terminal of the control voltage V ₁₀ to the second oscillation circuit 27 is inputted, 43 is an output end of the oscillator. In FIG. 8, 44 is a varicap diode.

Specifically, the control voltage supply unit 41 includes a frequency detection unit 45 including, for example, a frequency counter for measuring the frequency f from the frequency signal input from the second oscillation circuit 27, and the frequency detection unit 45 A temperature estimation unit 46 that estimates the temperature T based on the measured frequency f, a compensation voltage calculation unit 47 that calculates the compensation voltage ΔV based on the temperature T estimated by the temperature estimation unit 46, and a compensation voltage calculation unit 47 It includes an adder 48 for outputting a control voltage V _c to the computed compensation voltage ΔV is subtracted from the reference voltage V ₀ to the first oscillation circuit 17, the at. The temperature estimation unit 46 stores a frequency temperature characteristic (for example, a cubic function) of the second oscillation circuit 27 expressed by the following equation (1). This temperature characteristic and the oscillation frequency of the second oscillation circuit 27 are stored. Based on f, the temperature of the crystal unit is obtained.
f = f ₁₀ {1 + α ₂ (T−T ₁₀ ) ³ + β ₂ (T−T ₁₀ ) + γ ₂ } (1)

Further, the compensation voltage calculation unit 47 includes, for example, a cubic function generator that is a temperature characteristic of the first oscillation circuit 17, and the compensation voltage is calculated based on the following equations (2) to (4) and the temperature T. It is comprised so that (DELTA) V may be calculated | required.
ΔV = V ₀ (Δf / f ₀ ) (2)
Δf / f ₀ = α ₁ (T−T ₀ ) ³ + β ₁ (T−T ₀ ) + γ ₁ (3)
ΔV = V ₀ {α ₁ (T−T ₀ ) ³ + β ₁ (T−T ₀ ) + γ ₁ } (4)
α ₁ , β ₁ , γ ₁ and α ₂ , β ₂ , γ ₂ are constants specific to the first oscillating circuit 17 and the second oscillating circuit 27, respectively. It is obtained by measuring. Δf = f−f ₀ , and f ₁₀ is an output frequency obtained when the reference voltage V ₁₀ is applied at the reference temperature T ₁₀ in the second oscillation circuit 27.

When the control voltage V ₁₀ is input to the input terminal 42 in this oscillator, the second oscillation circuit 27 generates a fundamental wave at the oscillation frequency f obtained by the above-described equation (1) based on the temperature T of the crystal resonator. Oscillates with thickness shear vibration. As described above, the oscillation frequency f is input to the temperature estimation unit 46 via the frequency detection unit 45, and the temperature estimation unit 46 estimates the temperature T of the crystal resonator. The compensation voltage calculation unit 47 calculates the compensation voltage ΔV based on the temperature T obtained by the temperature estimation unit 46, and the control voltage V _c is applied to the first oscillation circuit 17 via the addition unit 48. The The first oscillation circuit 17 vibrates with thickness shear vibration at an oscillation frequency f corresponding to the temperature T of the crystal resonator and the control voltage V _c , that is, a set frequency f ₀ . That is, at the temperature T, the first oscillation circuit 17 causes the oscillation frequency f to follow the cubic function of the frequency temperature characteristic of the first oscillation circuit 17 by the difference (T−T _o ) from the reference temperature T _0. but when you Zureyo from the set frequency f _0. However, since the control voltage V _c for obtaining the set frequency f ₀ is applied to the first oscillation circuit 17, that is, the control voltage V lower (or higher) than the reference voltage V ₀ by the amount corresponding to the difference. _{Since c} is applied, an output frequency (set frequency f ₀ ) in which the difference is canceled is obtained.

  According to the above-described embodiment, the vibration parts 11 and 21 are provided on the common piezoelectric plate 1, the frame body 31 surrounding the vibration parts 11 and 21 is disposed, and the vibration part is disposed with respect to the frame body 31. Support portions 12 and 22 that respectively support 11 and 21 are provided on the piezoelectric plate 1. Therefore, a small crystal unit for obtaining a stable frequency signal over a wide temperature range can be configured. Further, as can be seen from FIG. 2 and the like, the crystal resonator is symmetrical with respect to the long side direction (X direction) via a straight line passing between the vibration portions 11 and 21 when viewed in a plane, and the support portion 12 and It is line symmetric also in the short side direction (Y direction) through straight lines passing through 12 and between the support portions 22 and 22. For this reason, for example, stress applied from the outside of the crystal resonator is evenly distributed, so that good mechanical strength can be obtained. In other words, good mechanical resistance can be obtained by making the configuration symmetrical in the vertical and horizontal directions in this way.

  In addition, since the electrode pads 15 and 25 connected to the excitation electrodes 13 and 23 of the vibrating portions 11 and 21 are provided on the frame-shaped body 31, mechanical stress from the exterior body 2 side, the piezoelectric vibrator It is possible to suppress the expansion and contraction of the electrode pads 15 and 25 due to an external temperature change from being transmitted to the vibrating portions 11 and 21 via the electrode pads 15 and 25. Further, by providing an elastic boundary region 32 for suppressing the propagation of vibration of the piezoelectric plate 1 between the vibrating parts 11 and 21, mutual interference between the vibrating parts 11 and 21 can be suppressed. Therefore, a stable output frequency can be obtained over a wide temperature range. Furthermore, since the elastic boundary region 32 is provided in the first support part 12 and the second support part 22, leakage of vibration energy from the vibration parts 11 and 21 to the support parts 12 and 22 can be suppressed. A stable output signal can be obtained, and deterioration (increase) in CI (crystal impedance) value can be suppressed. Further, in the crystal resonator of the present invention, good thermal hysteresis characteristics can be obtained.

  Other examples of the crystal resonator described above are listed below. Although an example in which the piezoelectric plate 1 is twinned as the elastic boundary region 32 has been described, it may be made amorphous. FIG. 9 shows an example in which grooves 33 are formed on both upper and lower surfaces as the elastic boundary region 32 instead of twinning the piezoelectric plate 1. This groove 33 is formed by, for example, wet etching before forming the excitation electrodes 13 and 23, for example. By forming the groove 33 in the piezoelectric plate 1 in this way, the film thickness of the piezoelectric plate 1 is thinner in the elastic boundary region 32 than in the region where the vibrating portions 11 and 21 are formed. For this reason, in the elastic boundary region 32, the resonance frequency changes with respect to the vibrating portions 11 and 21, so that the vibration of the piezoelectric plate 1 is difficult to propagate and the same effect as described above can be obtained. In FIG. 9, the drawing of the elastic boundary region 32 in the support portions 12 and 22 is omitted. The same applies to the subsequent FIGS.

  At this time, when a through-hole is formed between the vibrating parts 11 and 21, so that the vibrating parts 11 and 21 are separated, acoustic coupling occurs between the vibrating parts 11 and 21, and vibration energy propagates. It is preferable to form the groove 33 instead of the through hole. Further, the groove 33 may be formed only on either the upper surface side or the lower surface side, and FIG. 10 shows an example in which the groove 33 is formed on the upper surface side of the piezoelectric plate 1.

  Further, as the elastic boundary region 32, instead of twinning the piezoelectric plate 1 or forming the groove 33, a convex portion 34 may be provided as shown in FIG. The thickness dimension of the convex part 34 is set to, for example, about twice that of the piezoelectric plate 1 in each of the vibration parts 11 and 21. In the case of manufacturing a crystal resonator having such a convex portion 34, for example, after forming the piezoelectric plate 1 so as to have the thickness dimension of the convex portion 34, the elastic boundary region 32 is formed by photolithography and wet etching. Other regions (respective vibration parts 11, 21, etc.) are thinned, and then the excitation electrodes 13, 23, etc. are formed. By providing the convex portion 34, the resonance frequency becomes a value different from the region where the vibration portions 11 and 21 are formed, as in the case where the groove 33 is formed, and therefore the same effect as in each of the examples described above can be obtained. . Moreover, since the piezoelectric plate 1 becomes thicker than other portions (vibrating portions 11 and 21) by providing the convex portion 34, the mechanical strength of the piezoelectric plate 1 is improved. The protrusions 34 may also be provided on both the upper and lower surfaces as shown in FIG. 11, or may be provided only on either the upper surface side or the lower surface side.

  FIG. 12 shows an example in which the elastic boundary region 32 is formed only between the vibration parts 11 and 21 and not formed on the support parts 12 and 22. FIG. 13 shows an example in which the elastic boundary region 32 is not formed between the vibration parts 11 and 21 but formed on the support parts 12 and 22. Further, FIG. 14 shows an example in which the elastic boundary region 32 is formed only on the support portion 12 without forming the elastic boundary region 32 between the vibrating portions 11 and 21 and the support portion 22. As described above, in the present invention, the elastic boundary region 32 may be provided in at least one of the support portions 12 and 22 between the vibration portions 11 and 21.

As the piezoelectric plate 1 described above, an AT cut plate cut out so that the longitudinal direction is the X axis of the crystal axis is taken as an example, but an AT cut plate whose longitudinal direction is the Z axis may be used. Further, as the piezoelectric plate 1, a substrate in which the natural r-plane is exposed on both upper and lower surfaces may be used. When forming the r surface on the upper and lower surfaces of the piezoelectric plate 1, for example, a mask made of metal is formed on the side surface of the piezoelectric plate 1, and then, for example, ammonium fluoride (until the r surface is exposed on both the upper and lower surfaces. The piezoelectric plate 1 is immersed in NH ₄ F) liquid or the like. Thereafter, the elastic boundary region 32 and the excitation electrodes 13 and 23 are formed on the piezoelectric plate 1. Further, as the piezoelectric plate 1, a surface orthogonal to the Y axis of the crystal axis of the crystal is rotated about 33 ° around the X axis, and is rotated about 22 ° around the new Z ′ axis from this position. You may use the SC cut board cut out from. When this SC cut plate is used, as the elastic boundary region 32, the piezoelectric plate 1 may be made amorphous by irradiating a femtosecond laser. This SC cut plate is suitably used for OCXO (Temperature Compensated Crystal Oscillator) described later.

  Further, as shown in FIG. 15, the bumps 16 and 26 may be provided at positions separated from the support portions 12 and 22. In this example, the bump 16 is formed on the frame-like body 31 on the second vibrating portion 21 side with respect to the first vibrating portion 11, and the bump 26 has the first vibration than the second vibrating portion 21. It is formed in the frame-like body 31 on the part 11 side. In other words, it can be said that the bumps 16 and 26 are arranged so as to be separated from the support portions 12 and 22 as much as possible on the peripheral surface surrounding the piezoelectric plate 1. Accordingly, the bumps 16 and 26 are arranged at positions close to each other. Thus, by separating the bumps 16 and 26 and the support portions 12 and 22, it is possible to further suppress the influence of mechanical stress and thermal stress from the bumps 16 and 26 side (the outer package 2).

  Further, as shown in FIG. 16, the elastic boundary region 32 may not be formed. Further, instead of supporting the configuration including the vibrating portions 11 and 21 from the left and right sides, as shown in FIG. 17, for example, the vibrating portions 11 and 21 may be supported in a cantilevered manner from the front side. . Even in such a configuration, the elastic boundary region 32 may be formed in the same manner as in the examples described above.

The TCXO shown in FIG. 8 is taken as an example of the oscillator including the crystal resonator of the present invention. However, since the frequency temperature characteristics of the vibrating parts 11 and 21 are uniform, the frequency between the vibrating parts 11 and 21 is the same. The difference is a substantially constant value over a wide temperature range. Therefore, it may be used to this difference as a set frequency f _0. In this case, the calculation unit that calculates the difference serves as a signal output unit. Further, a waveform shaping filter may be provided on the rear side of the first vibration unit 11 (between the first vibration unit 11 and the output end 43) in the TCXO. Then, as this waveform shaping filter, a quartz crystal resonator in which a pair of excitation electrodes is provided on the piezoelectric plate 1 common to the first vibrating portion 11 and the second vibrating portion 21 in the same manner as the vibrating portions 11 and 12. By using, the frequency temperature characteristics of the vibrating parts 11 and 12 and the filter are aligned. Therefore, by using such a filter, a signal having a favorable waveform can be obtained without disturbing the waveform of the output signal output from the first vibrating unit 11.

  In addition to TCXO, the crystal resonator of the present invention may be applied to OCXO. In this case, by using the crystal resonator of the present invention instead of the temperature detection sensor used when controlling the heater of the OCXO, specifically, the difference between the oscillation frequencies of the vibration parts 11 and 21 is calculated. By using this difference as a temperature detection signal, a small OCXO can be obtained.

DESCRIPTION OF SYMBOLS 1 Piezoelectric plate 11, 21 Vibration part 12, 22 Support part 13, 23 Excitation electrode 14, 24 Extraction electrode 17, 27 Oscillation circuit 31 Frame-shaped body 32 Elastic boundary area

Claims (4)

A first vibration unit and a second vibration unit configured to be provided with a pair of excitation electrodes on both sides of each of the left and right regions of the piezoelectric plate and having different resonance frequencies;
A frame-like body formed on the piezoelectric plate so as to surround the first vibrating portion and the second vibrating portion via a gap region;
From the left part of the frame-like body, the first support part extending toward the first vibration part to support the first vibration part, and from the right part of the frame-like body, the second part A second support portion extending toward the second vibration portion to support the vibration portion;
A first lead electrode formed on the first support part and connected to the excitation electrode of the first vibration part, and an excitation of the second vibration part formed on the second support part. A second extraction electrode connected to the electrode;
A first electrode pad and a second electrode pad provided on the frame-like body and connected to the first extraction electrode and the second extraction electrode, respectively;
Between the first vibrating part and the second vibrating part, the first supporting part and the second supporting part are formed in at least one place for suppressing propagation of vibration of the piezoelectric plate. And a boundary region.   One electrode pad of the first electrode pad and the second electrode pad is for suppressing stress from being transmitted through the electrode pad to one vibrating portion connected to the electrode pad. The piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrator is disposed at a position close to the other vibration part side on the frame-like body. A first vibration unit and a second vibration unit configured to be provided with a pair of excitation electrodes on both sides of each of the left and right regions of the piezoelectric plate and having different resonance frequencies;
A frame-like body formed on the piezoelectric plate so as to surround the first vibrating portion and the second vibrating portion via a gap region;
In order to support the first vibration part and the second vibration part, respectively, a first support part and a first support part extending from the frame body toward the first vibration part and the second vibration part, respectively. Two support parts;
A first lead electrode formed on the first support part and connected to the excitation electrode of the first vibration part, and an excitation of the second vibration part formed on the second support part. A second extraction electrode connected to the electrode;
A piezoelectric vibrator comprising: a first electrode pad and a second electrode pad provided on the frame-like body and connected to the first lead electrode and the second lead electrode, respectively. . The piezoelectric vibrator according to any one of claims 1 to 3,
A first oscillation circuit connected to the first electrode pad;
A second oscillation circuit connected to the second electrode pad to use the second vibrating section as a temperature sensor;
An oscillator comprising: a signal output unit for obtaining a set frequency signal based on respective output signals of the first oscillation circuit and the second oscillation circuit.