JP2011228980A - Vibration piece, vibrator, oscillator, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration piece which is improved in Q value, and a vibrator and an oscillator which use the same, or an electronic apparatus which uses the same.SOLUTION: Excitation electrodes each comprising a stack formed by stacking a first electrode 20, a piezoelectric film 22, and a second electrode 26 in this order are formed on first surfaces 12 of respective vibration arms 18a, 18b and 18c extended from one end portion of a base 16 of a vibration piece 1 in parallel. Members 30 made of materials which are insulating materials and have lower thermal resistivity than crystal as forming materials of at least the vibration arms 18a, 18b and 18c and the base 16 are formed covering the entire regions of the vibration arms 18a, 18b and 18c where the second electrodes 26 are formed, and the base 16 nearby roots of the respective vibration arms 18a,18b and 18c for the base 16, and also leaving gaps so as to make the respective vibration arms 18a, 18b and 18c thermally independent.

Description

  The present invention relates to a resonator element, a vibrator and an oscillator using the resonator element, or an electronic apparatus using the resonator element.

  Conventionally, as a flexural vibration piece that vibrates in a flexural vibration mode, for example, a pair of vibration arms are extended in parallel from a base portion made of a base material for a flexural vibration body such as a piezoelectric material, and the vibration arms are horizontally aligned. Tuning-fork type bending vibration pieces that vibrate in directions toward or away from each other are widely used. When the vibration arm of the tuning fork-type bending vibration piece is excited, if a loss occurs in the vibration energy, it causes a decrease in the performance of the vibration piece, such as an increase in CI (Crystal Impedance) value and a decrease in Q value. Therefore, various ideas have been conventionally made in order to prevent or reduce such loss of vibration energy.

  For example, a tuning-fork type crystal vibrating piece in which cut portions or cut grooves having a predetermined depth are formed on both sides of a base portion from which a vibration arm extends is known (see, for example, Patent Document 1 and Patent Document 2). This tuning fork type crystal vibrating piece improves the confinement effect of vibration energy by suppressing the leakage of vibration from the base portion by the cut portion or the cut groove when the vibration of the vibration arm also includes a vertical component. The value is controlled, and the variation of the CI value between the resonator elements is prevented.

In addition to the loss of mechanical vibration energy, a temperature difference occurs between the compression part where the compressive stress of the vibrating arm that vibrates and the extension part where the tensile stress acts, and this acts to alleviate this temperature difference. Loss of vibration energy also occurs due to heat conduction. This decrease in the Q value caused by heat conduction is called a thermoelastic loss effect.
In order to prevent or suppress such a decrease in the Q value due to the thermoelastic loss effect, a tuning-fork type vibrating piece in which a groove or a hole is formed on the center line of a vibrating arm (vibrating beam) having a rectangular cross section is disclosed in, for example, a patent. It is introduced in Reference 3.

The resonator element described in Patent Document 3 will be specifically described with reference to the drawings.
In FIG. 9, the resonator element of Patent Document 3 is a tuning-fork type crystal resonator element 100 made of crystal, and includes a base portion 102 and two mutually parallel vibrating arms 103 and 104 extending from the base portion 102. In addition, linear grooves or holes 106 and 107 are provided on the center lines of the vibrating arms 103 and 104, respectively. When a predetermined drive voltage is applied to excitation electrodes (not shown) provided on both main surfaces (the same surfaces as the grooves or holes 106 and 107) of the vibration arms 103 and 104 of the tuning-fork type crystal vibrating piece 100, the vibration arms 103 and 104 bend and vibrate in directions toward or away from each other, as indicated by imaginary lines (two-dot chain lines) and arrows in the figure.

Due to this bending vibration, a mechanical strain is generated in a base region with the base 102 of each vibration arm 103, 104. That is, at the base of the vibration arm 103 with the base 102, a first region 110 where compressive stress or tensile stress acts by bending vibration, and when compressive stress acts on the first region 110, tensile stress acts, When tensile stress is applied to the first region 110, there is a second region 111 in a relationship in which compressive stress is applied. In these first region 110 and second region 111, the temperature is applied when the compressive stress is applied. Rises and the temperature drops when tensile stress is applied.
Similarly, at the base of the vibration arm 104 with the base portion 102, a first region 112 in which compressive stress or tensile stress is applied by bending vibration, and when compressive stress is applied to the first region 112, tensile stress is applied. When the tensile stress acts on the first region 112, there is a second region 113 in which the compressive stress acts, and the compressive stress acts on the first region 112 and the second region 113. Sometimes the temperature rises, and when tensile stress is applied, the temperature falls.

Due to the temperature gradient generated in this way, heat conduction is generated between the first regions 110 and 112 and the second regions 111 and 113 inside the base portion of the vibration arms 103 and 104 with the base 102. . The temperature gradient is generated in the opposite direction corresponding to the bending vibration of each of the vibrating arms 103 and 104, and the heat conduction is also reversed in the corresponding direction. Due to this heat conduction, a part of the vibration energy of the vibration arms 103 and 104 is always lost as a thermoelastic loss even during vibration. As a result, the Q value of the tuning-fork type crystal vibrating piece 100 is lowered and vibration characteristics are not good. It becomes stable and it becomes difficult to achieve desired performance.
In the tuning-fork type crystal vibrating piece 100 of Patent Document 3, heat transfer from the compression side to the tension side is prevented by grooves or holes 106, 107 provided on the center lines of the respective vibrating arms 103, 104. It is possible to prevent or reduce the decrease in the Q value due to the elastic loss. Specifically, by bypassing the bending vibration body along the grooves or holes 106 and 107 provided in the vibration arms 103 and 104, the heat conduction path becomes long and the thermal relaxation time τ is extended. 1 / thermal relaxation frequency obtained in (2.pi..tau), as shown in relaxation frequency f ₁₀ of the curve F ₁ shown in FIG. 10, the curve F and its relaxation frequency f ₀ of the conventional quartz crystal resonator element is not provided with grooves or holes Shifts to the left in the figure.

JP 2002-261575 A Japanese Patent Laid-Open No. 2004-260718 Actual Application No. Sho 63-110151

  However, in the tuning-fork type crystal vibrating piece 100 described in Patent Document 3, it is very difficult to form a groove or a hole because the vibrating arm becomes a thin piece as the miniaturization progresses, and thermal relaxation is performed by the groove or the hole. There is a problem that the effect of extending the time is reduced, and the effect of suppressing the decrease in the Q value cannot be obtained sufficiently.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A vibrating piece according to this application example includes a base, and a vibrating arm extending from one end of the base and provided with a drive electrode on a first surface. A first region where compressive stress or tensile stress is applied to one surface by vibration of the vibrating arm; a second surface connected to the first surface by a side surface perpendicular to the first surface; and the first region. A second region that has a relationship in which a tensile stress acts when compressive stress acts and a compressive stress acts when tensile stress acts on the first region, and the first region and the second region And the side surface connecting the first region and the second region is covered with a member made of a material having a lower thermal resistivity than a material forming at least the base and the vibration arm. And

According to this configuration, the member that thermally connects the first region and the second region serves as a heat conduction path, and heat conduction between the first region and the second region is efficient via the heat conduction path. Therefore, the thermal relaxation time required to bring the temperature of the first region and the second region into an equilibrium state is shortened, and a decrease in Q value can be suppressed. Further, the thermal relaxation frequency curve of the present invention is shifted to a higher frequency side than the conventional thermal relaxation frequency curve when no groove or hole is provided, and the mechanical vibration frequency (resonance frequency) of the vibrating arm is fr. In the range where fr is less than or equal to the thermal relaxation frequency f ₀ , that is, in the range satisfying 1 ≧ fr / f ₀ , the Q value in the thermal relaxation frequency curve of the present invention is always higher than the thermal relaxation frequency curve of the conventional structure. Also gets higher. Further, even in a range lower than the frequency of the intersection of the thermal relaxation frequency curve of the present invention and the thermal relaxation frequency curve of the conventional structure, the Q value of the conventional structure is higher.
Moreover, since it is not necessary to form holes or grooves in the bending vibration body as in the conventional measures described above, it is easy to cope with downsizing of the bending vibration piece.
Therefore, it is possible to provide a small flexural vibration piece that suppresses a decrease in the Q value and has stable vibration characteristics.

  Application Example 2 In the resonator element according to the application example described above, the member includes one layer or a plurality of layers, and at least a part or all of the member that contacts the first surface, the second surface, and the side surface of the member. Is made of a non-conductive material.

According to this configuration, it is possible to provide a heat conduction path on the electrodes without worrying about a short circuit with an excitation electrode or the like, which increases the degree of freedom in design and is advantageous for downsizing. Also, the manufacture becomes easy.
Furthermore, since a heat transfer road between the first region and the second region can be formed by a single member made of a non-conductive material, the heat relaxation time can be shortened and the decrease in the Q value can be suppressed by a simple process. can do.

  Application Example 3 In the resonator element according to the application example, the non-conductive material is diamond.

  The inventor has found that the reduction of the Q value can be suppressed particularly effectively by forming the member using diamond having a particularly low thermal resistivity.

  Application Example 4 In the resonator element according to the application example, the member is formed on the insulating base layer formed on the first surface, the second surface, and the side surface, and on the base layer. And a metal layer.

  According to this configuration, by interposing the insulating film as the base layer, the thermal relaxation time can be shortened by the metal layer made of a wide range of metal materials, and the decrease in the Q value can be suppressed.

  Application Example 5 In the resonator element according to the application example, the base portion and the vibration arm are formed using a piezoelectric material.

  According to this configuration, by using a piezoelectric material that has been widely used as a material for a resonator element, a high-performance piezoelectric resonator element that uses the piezoelectric effect in consideration of known principles and know-how is provided. be able to.

  Application Example 6 In the resonator element according to the application example, crystal is used as the piezoelectric material.

  According to this configuration, by using quartz, it is possible to suppress a decrease in temperature characteristics (temperature dependence such as frequency characteristics) associated with downsizing of the resonator element.

  Application Example 7 A vibrator according to this application example includes the resonator element according to the application example and a package that accommodates the resonator element.

  According to this configuration, since the resonator element in which the decrease in the Q value shown in the application example is suppressed is provided, a vibrator having stable vibration characteristics can be provided.

  Application Example 8 An oscillator according to this application example includes the resonator element according to the application example, a circuit element including an oscillation circuit that oscillates the resonator element, and a package that accommodates the resonator element and the circuit element. It is characterized by including.

  According to this configuration, since the resonator element in which the decrease in the Q value shown in the application example is suppressed is provided, a small-sized oscillator having stable oscillation frequency characteristics and low power consumption is provided. Can do.

  Application Example 9 An electronic apparatus according to this application example includes the vibrator according to the application example or the oscillator according to the application example.

  According to this configuration, since the vibrator having the stable vibration characteristics according to the application example or the oscillator having the stable oscillation frequency characteristics according to the application example is mounted, the structure is small and has excellent characteristics. Can be provided.

FIG. 6 is a schematic plan view illustrating one embodiment of a vibrating piece. (A), (b) is a perspective view which shows the process of electrode formation of a vibration piece, (c) is the sectional view on the AA 'line of (a), (d) is BB of (b). A sectional view taken along the line ′. (E), (f) is a perspective view which shows the process of electrode formation of a vibration piece, (g) is CC 'sectional view taken on the line of (e), (h) is DD of (f). A sectional view taken along the line ′. The figure which shows the material applicable as a material for forming a member, and each thermal resistivity. The diagram showing the relationship between the relaxation frequency for every member formation material in the vibration piece which formed the member, and the minimum value of Q value. (A) is a schematic plan view explaining one Embodiment of the vibrator | oscillator using the resonator element of this invention, (b) is the EE 'sectional view taken on the line of (a). (A) is a schematic plan view explaining one Embodiment of the oscillator using the resonator element of this invention, (b) is FF 'sectional view taken on the line of (a). FIG. 6 is a schematic cross-sectional view illustrating a modification of a resonator element. FIG. 6 is a schematic plan view showing a typical example of a conventional vibrating piece (tuning fork type quartz vibrating piece). The diagram showing the relationship between the relaxation frequency and the minimum value of Q value in the vibration piece in the bending vibration mode. (A) is a figure which shows the mobile telephone as an electronic device carrying the vibrator | oscillator and oscillator of this invention, (b) is a figure which similarly shows the mobile computer as an electronic device.

  Hereinafter, an embodiment of a resonator element according to the invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic plan view for explaining an embodiment of a resonator element. 2 and 3 illustrate the process of electrode formation of the resonator element. FIGS. 2A and 2B are perspective views, and FIG. 2C is the AA ′ line in FIG. Sectional view, (d) is a sectional view taken along line BB 'in (b), FIGS. 3 (e) and (f) are perspective views, (g) is a sectional view taken along line CC' in (e), (h) ) Is a sectional view taken along line DD 'in (f).

[Vibration piece]
In FIG. 1, the resonator element 1 according to the present embodiment includes a base portion 16 formed by processing a resonator element forming material, and three base portions extending in parallel from one end side (the upper end side in the drawing) of the base portion 16. The vibrating arms 18a, 18b, and 18c are formed. As the vibrating piece forming material, for example, a piezoelectric material can be used. In the present embodiment, a material that is cut out from a single crystal of quartz that has been widely used as a piezoelectric vibrating piece forming material is used. For example, from a so-called Z-cut crystal thin plate, the Y axis of the crystal crystal axis is in the extending direction of the vibrating arms 18a, 18b, 18c, the X axis is in the width direction orthogonal to the extending direction, and the Z axis is in the vibrating piece. The first surface 12 and the second surface 10 as the front and back main surfaces are formed so as to be oriented in the vertical direction. The external shape of such a resonator element 1 can be precisely formed by wet etching or dry etching a quartz substrate material (quartz wafer) with a hydrofluoric acid solution or the like using photolithography, for example. .

Note that a piezoelectric material other than the above-described quartz can be used as the vibrating piece forming material. For example, oxide substrates such as aluminum nitride (AlN), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), lead zirconate titanate (PZT), and lithium tetraborate (Li ₂ B ₄ O ₇ ) A piezoelectric substrate formed by stacking a piezoelectric material such as aluminum nitride or tantalum pentoxide (Ta ₂ O ₅ ) on a glass substrate can be used.
In addition to the piezoelectric material, the resonator element can be formed of, for example, a silicon semiconductor material.
However, the resonance frequency of the bending vibration piece is proportional to the square root of the value obtained by dividing the Young's modulus of the bending vibration material by the mass density, and the smaller the value obtained by dividing the Young's modulus by the mass density, the smaller the bending vibration piece. It is advantageous. Therefore, the bending vibration piece made of crystal like the vibration piece 1 of the present embodiment is advantageous for miniaturization because the square root of the value obtained by dividing the Young's modulus by the mass density can be reduced as compared with a silicon semiconductor material or the like. Since the frequency temperature characteristics are excellent, the material used for the resonator element 1 is particularly preferable.

Excitation electrodes are formed on the first surface 12 of each vibration arm 18a, 18b, 18c. The excitation electrode of the resonator element 1 according to the present embodiment includes a laminated body in which the first electrode 20, the piezoelectric film 22, and the second electrode 26 are laminated in this order (details of each electrode and the piezoelectric film will be described later). To do).
Excitation electrodes formed on each vibration arm are drawn out to the base 16 and connected to external connection electrodes 26 a and 26 b provided on the base 16 for connection to the outside. In the present embodiment, of the three vibrating arms, the first electrode 20 formed on the vibrating arms 18 a and 18 c at both ends and drawn out to the base 16, and formed on the central vibrating arm 18 b and drawn out to the base 16. The first electrode 20 and the second electrode 26 connected in conduction by two openings 24 (corresponding to each of the external connection electrodes 26a and 26b) formed in the piezoelectric film 22 on the base 16 are used to connect the external connection electrode 26a. 26b are formed).

Further, the first surface 12, the second surface 10, and both side surfaces connecting the first surface 12 and the second surface 10 of the vibration arms 18a, 18b, 18c of the vibration piece 1, and the vibration arms 18a, 18b. , 18c, an insulating member 30 made of a material having low thermal resistivity is formed in a region including the vicinity of the base with the base portion 16. In the resonator element 1 of the present embodiment, the member 30 includes an excitation electrode including the first electrode 20, the piezoelectric film 22, and the second electrode 26 provided on the vibration arms 18a, 18b, and 18c, and the vibration arms 18a. , 18b, 18c are provided with a gap so as to cover the base 16 and the base of the base portion 16 up to the base portion 16, and the members 30 formed on the respective vibration arms 18a, 18b, 18c are thermally independent. ing.
The vibration piece 1 having such a configuration includes, among the three vibration pieces, the vibration arms 18 a and 18 c at both ends having the external connection electrode 26 a as a common electrode, and the vibration arm 18 b at the center are the first surface 12 and the second vibration piece 18. Bending vibration is alternately performed in a direction (Z direction) orthogonal to the surface 10.

[Electrode formation]
Next, the process of forming the electrode of the resonator element 1 will be described.
As shown in FIGS. 2A and 2C, first, the first electrode 20 is formed on the first surface 12 of the vibrating arms 18a, 18b, and 18c. In the present embodiment, the first electrode 20 is approximately 2 minutes the length of each vibration arm 18a, 18b, 18c in the extending direction from the base to the base 16 of the vibration arms 18a, 18b, 18c toward the tip side. In order to make an electrical connection with the external connection electrodes 26a and 26b to be formed on the base portion 16 later, a lead-out wiring is formed on the base portion 16.

Next, as shown in FIGS. 2B and 2D, the piezoelectric film 22 is formed so as to cover the first electrode 20 and a part of the base portion 16, and the first electrode 20 and later are formed on the piezoelectric film 22. An opening 24 for conducting connection with the second electrode 26 to be formed is formed.
Next, as shown in FIGS. 3E and 3G, the second electrode 26 is formed on the piezoelectric film 22. At this time, the first electrode 20 of the vibrating arms 18a and 18c and the second electrode 26 of the vibrating arm 18b are connected via one opening 24 of the piezoelectric film 22, and the second electrode 26 of the vibrating arms 18a and 18c is connected to the second electrode 26. The first electrode 20 of the vibration arm 18 b is connected to the other opening 24 of the piezoelectric film 22, and the corresponding external connection electrodes 26 a and 26 b provided by being drawn out from the second electrode 26 onto the base 16. Connected to.

  Next, as shown in FIGS. 3 (f) and 3 (h), the entire surface of the region where the second electrode 26 of each vibration arm 18a, 18b, 18c is formed, and the base of each vibration arm 18a, 18b, 18c. 16 so as to cover the base 16 in the vicinity of the base to the base 16 and to provide a gap so as to make the vibration arms 18a, 18b, 18c thermally independent, and is insulative, and at least the vibration arms 18a, 18b. , 18c and the base portion 16 are formed, the vibrating element 1 is completed by forming the member 30 made of a material having lower thermal efficiency than that of quartz.

  As described above, the vibration of the vibration piece 1 is the vibration of the first surface 12 and the second surface 10 by the vibration arms 18a, 18c at both ends and the vibration arm 18b at the center of the three vibration arms 18a, 18b, 18c. Bending vibrations alternately in a direction (Z direction) perpendicular to the axis. By this bending vibration, compressive stress and tensile stress are generated on the front and back surfaces of the base portion in the vibration direction of the vibration arms 18a, 18b, 18c at the connecting portion between the base 16 and the vibration arms 18a, 18b, 18c. When the vibration arms 18a and 18c bend and vibrate in the + Z-axis direction, the compressive stress acts on the first region on the surface (the first surface 12 side) of the vibration arms 18a and 18c. The temperature rises, and tensile stress acts on the second region of the back surface (second surface 10), and the temperature falls. On the other hand, the vibrating arm 18b bends and vibrates in the −Z-axis direction, the tensile stress acts on the first region of the surface of the vibrating arm 18b, the temperature drops, and the compressive stress acts on the second region of the back surface. The temperature rises. As described above, a temperature gradient is generated between the portion where the compressive stress acts and the portion where the tensile stress acts inside the connecting portion of each of the vibrating arms 18a, 18b, and 18c with the base portion 16, and the inclination is The direction is reversed depending on the vibration direction of the vibration arms 18a, 18b, and 18c. Due to this temperature gradient, heat is transferred from the compression side portion to the tension side portion, that is, from the high temperature side to the low temperature side. In the resonator element 1 of the present embodiment, the surface of the vibrating arms 18a, 18b, and 18c is used for heat transfer from the compression side portion to the extension side portion (heat transfer between the first region and the second region). And a material having a lower thermal resistivity than a crystal (thermal resistivity = 0.125 mk / W) formed so as to cover the base 16 near the base with the base 16 of each vibration arm 18a, 18b, 18c. A part of the member 30 is used as a heat conduction path.

As described above, the member 30 serving as the heat conduction path between the first region and the second region is made of a material having a thermal resistance lower than that of the crystal that is the material for forming the resonator element 1. The heat conduction time from the compression side to the expansion side is faster than in the case of the conventional structure in which the inside of the base material (quartz) of the piece 1 is a heat conduction path between the first region and the second region. That is, the relaxation time τ ₁ until the temperature is in an equilibrium state between the first region and the second region when the vibration arms 18a, 18b, 18c of the resonator element 1 flexurally vibrates has no conventional heat conduction path. It becomes shorter than the relaxation time τ _{0 of the} structure. Therefore, since τ ₁ <τ ₀ at the thermal relaxation frequency f ₂₀ = 1 / (2πτ ₁ ) of the resonator element 1 of the present embodiment, the thermal relaxation frequency f ₀ = 1 / (2πτ _{0 of the} resonator _{element having the} conventional structure. ).
Looking at the relationship between the mechanical vibration frequency (resonance frequency) and the Q value of the resonator element in FIG. 10, the shape of the curve F itself does not change. This means that the frequency has shifted to the position of the curve F _{2 in} the direction of increasing frequency (to the right in the drawing). Therefore, in the range where fr is equal to or less than the thermal relaxation frequency f ₀ when the mechanical vibration frequency (resonance frequency) of the vibrating arm is fr, the curve F2 is in a range satisfying 1 ≧ fr / f ₀ (region A). The Q value at is always higher than the curve F of the conventional structure. In addition, in the frequency band lower than the frequency of the intersection of the curve F and the curve F2 in the curve F2, it becomes higher than the Q value in the curve F of the resonator element having the conventional structure.
As described above, the resonator element 1 of the present embodiment has the surface of the vibration arms 18a, 18b, and 18c and the base portion 16 of each vibration arm 18a, 18b, and 18c in the heat transfer between the first region and the second region. A part of the member 30 made of a material having a lower thermal resistivity than that of the quartz formed so as to cover the base 16 near the base of the substrate functions as a heat conduction path, thereby improving the Q value and improving the performance. Can be realized.
In addition, unlike the conventional measures for suppressing the decrease in the Q value due to the thermoelastic loss, it is not necessary to form holes or grooves in the vibrating body, so that it is possible to cope with the size reduction of the vibrating piece. Thus, it is possible to provide the resonator element 1 that is small in size and has a stable vibration characteristic while suppressing a decrease in the Q value.

[Material for forming members]
Here, a specific example of a material for forming the member 30 that functions as a heat conduction path between the first region and the second region in the resonator element 1 of the present embodiment will be described with reference to the drawings.
FIG. 4 is a diagram showing examples of materials applicable as the material for forming the member 30 and the thermal resistivity of each. However, FIG. 4 includes a material that does not satisfy insulating properties, that is, a conductive material (metal), among the necessary requirements for the member 30 provided in the resonator element 1 of the present embodiment.
FIG. 5 is a diagram showing the result of confirming the relationship between the relaxation frequency and the minimum Q value in the resonator element 1 on which the member 30 is formed for each of the plurality of member 30 forming materials. The horizontal axis in FIG. 5 indicates a value (fr / f ₀ ) obtained by dividing the mechanical vibration frequency fr by the thermal relaxation frequency f ₀ , and the vertical axis indicates the Q value.

First, in FIG. 4, a material that can be used for the member 30 formed in the resonator element 1 of the present embodiment, that is, an insulating material and a material for forming the base portion 16 and the vibrating arms 18 a, 18 b, and 18 c. The materials with lower thermal efficiency than quartz are diamond (C), aluminum nitride (AlN), and silicon (Si).
In addition to the insulating member 30 forming material, a conductive metal among the materials shown in FIG. 4 should be used in combination with an insulating material as will be described in a later-described modification. Therefore, it can be used as a member forming material of the present invention.

Further, as a result of confirming the relationship between the relaxation frequency and the minimum value of the Q value in the resonator element 1 in which the member 30 is formed of a part of the member forming material illustrated in FIG. 4, as illustrated in FIG. 5, The inventor has found that the Q value of the resonator element in which the member is formed of diamond is particularly improved. More specifically, in FIG. 5, when the thickness of the vibrating arms 18a, 18b, 18c in the Z direction is reduced, the characteristics when the member 30 is Qz, Au, Cr, Ti, Al, Mo, AlN. 1 can suppress the deterioration of the Q value due to the thermoelastic loss in the range of fr / f ₀ ≦ 1 (region B). The characteristic 2 when the member 30 is diamond is shifted to a higher frequency side (right side in the figure) than the characteristic 1, and fr / f ₀ is lower than the intersection of the characteristic 1 and the characteristic 2 (region C). ), The deterioration of the Q value due to the thermoelastic loss can be suppressed. That is, by using diamond for the member 30, the range in which the thermoelastic loss can be improved can be expanded as compared with the case where Qz, Au, Cr, Ti, Al, Mo, and AlN are used.
From this result, it can be said that diamond is particularly preferable as a material for forming the insulating member 30 formed in the resonator element 1 of the present embodiment in view of the effect of improving the Q value.

(Second Embodiment)
[Vibrator]
Next, a vibrator using the vibrating piece 1 will be described.
FIGS. 6A and 6B are diagrams for explaining an embodiment of a vibrator using the resonator element 1, wherein FIG. 6A is a schematic plan view seen from above, and FIG. 6B is a cross-sectional view taken along line EE of FIG. It is. 6A illustrates a state in which the lid 91 (see FIG. 6B) provided above the vibrator 500 is removed for convenience of describing the internal structure of the vibrator.

  In FIG. 6, the vibrator 500 has a package 70 provided with a recess having a step. The resonator element 1 is joined to the concave bottom portion of the concave portion of the package 70, and a lid 91 as a lid is joined to the open upper end of the package 70.

  The package 70 is formed by laminating a rectangular annular second layer substrate 72 and a third layer substrate 73 having different opening sizes on a flat plate-like first layer substrate 71 in this order. A recess having an opening and a step in the interior is formed. As a material of the package 70, for example, ceramic, glass, or the like can be used.

In the recess of the package 70, a plurality of vibration piece connection terminals 76 to which the vibration piece 1 is bonded are provided on the step formed by the second layer substrate 72. In addition, an external mounting terminal 75 used for bonding to an external substrate or the like is provided on the surface opposite to the concave surface of the first layer substrate 71 which is the outer bottom surface of the package 70.
In the above-described various terminals provided in the package 70, the corresponding terminals are connected to each other by an intra-layer wiring such as a lead wiring or a through hole (not shown).

  The resonator element 1 is bonded to the recess of the package 70. In the present embodiment, the resonator element provided on the step formed by the second layer substrate 72 of the package 70 on the surface opposite to the surface on which the external connection electrodes 26 a and 26 b of the base portion 16 of the resonator element 1 are formed. It is bonded and fixed in the vicinity of the connection terminal 76 via a bonding member 99 such as an adhesive, and the external connection electrodes 26a and 26b of the vibration piece 1 and the corresponding vibration piece connection terminal 76 of the package 70 are bonded to the bonding wire. 95 is electrically connected. As a result, the resonator element 1 is cantilevered with the vibration arms 18 a, 18 b, and 18 c as free ends while leaving a gap between the resonator element 1 and the first layer substrate 71 that forms the concave bottom portion of the recess in the package 70. Fixed in a manner.

  As shown in FIG. 6B, a lid 91 as a lid is disposed on the upper end of the package 70 to which the resonator element 1 is bonded in the recess, and the opening of the package 70 is sealed. As the material of the lid 91, for example, a metal such as 42 alloy (an alloy containing 42% nickel in iron) or Kovar (an alloy of iron, nickel and cobalt), ceramics, glass, or the like can be used. The lid 91 made of metal can be joined to the package 70 by, for example, seam welding via a seal ring 79 formed by punching a Kovar alloy or the like into a rectangular ring shape. An internal space formed in the package 70 by joining the lid 91 becomes a space for the vibration piece 1 to operate. The internal space can be sealed and sealed in a reduced pressure space or an inert gas atmosphere.

  According to the vibrator 500 having the above-described configuration, since the resonator element 1 having the above-described structure is provided, the member 30 provided on the resonator element 1 efficiently performs thermal relaxation between the first region and the second region. As a result, the thermal relaxation time is shortened and thermoelastic loss is suppressed, so that a small vibrator 500 having a high Q value and excellent vibration characteristics can be provided.

(Third embodiment)
[Oscillator]
Next, an oscillator using the vibrating piece 1 will be described.
FIGS. 7A and 7B illustrate an embodiment of an oscillator on which the resonator element 1 is mounted. FIG. 7A is a schematic plan view seen from above, and FIG. 7B is a cross-sectional view taken along line FF ′ in FIG. It is. FIG. 7A shows a state in which the lid 92 provided above the oscillator 600 is removed for convenience of explaining the internal structure of the oscillator.

  In FIG. 7, the oscillator 600 includes a package 80 provided with a recess having a step. An IC chip 60 as a circuit element and the resonator element 1 disposed above the IC chip 60 are joined to the concave bottom portion of the concave portion of the package 80, and a lid is formed on the upper end of the package 80 having an opening. The lid 92 is joined.

The package 80 is configured by laminating a rectangular annular second layer substrate 82, a third layer substrate 83, and a fourth layer substrate 84 having different opening sizes on a flat first layer substrate 81 in this order. As a result, a recess having an opening on the upper surface side and having a step inside is formed.
A die pad 86 on which the IC chip 60 is disposed is provided on the first layer substrate 81 which is a concave bottom portion of the concave portion of the package 80. In addition, an external mounting terminal 85 used for bonding to an external substrate or the like is provided on the surface opposite to the surface on which the die pad 86 of the first layer substrate 81 is provided as the outer bottom surface of the package 80.
A plurality of IC connection terminals 87 for electrical connection with the IC chip 60 are provided on the step formed by the second layer substrate 82 in the recess of the package 80. On the step formed by the third layer substrate 83, a plurality of vibrating piece connection terminals 88 to which the vibrating piece 1 is bonded are provided. As described above, the various terminals provided in the package 80 are connected to each other by inter-layer wirings such as routing wirings and through holes (not shown).

  The IC chip 60 is a semiconductor circuit element including an oscillation circuit that oscillates the resonator element 1 and a temperature compensation circuit. The IC chip 60 is bonded and fixed to, for example, a brazing material 98 on a die pad 86 provided on the concave bottom portion of the concave portion of the package 80. Further, in the present embodiment, the IC chip 60 and the package 80 are electrically connected using a wire bonding method. Specifically, the plurality of electrode pads 35 provided on the IC chip 60 and the corresponding IC connection terminals 87 of the package 80 are connected by bonding wires 95.

  In addition, the resonator element 1 is bonded to the concave portion of the package 80 above the IC chip 60. Specifically, the base 16 of the resonator element 1 is bonded to the vicinity of the resonator element connection terminal 88 provided on the step formed by the third layer substrate 83 of the package 80 via a bonding member 99 such as an adhesive. In addition to being fixed, the external connection electrodes 26 a and 26 b of the resonator element 1 and the corresponding resonator element connection terminals 88 of the package 80 are electrically connected by the bonding wire 95. As a result, the resonator element 1 is fixed in a manner that it is cantilevered with the vibration arms 18 a, 18 b, and 18 c as free ends while leaving a gap between the resonator element 1 and the IC chip 60 bonded downward in the package 80. The

  As shown in FIG. 7B, a lid 92 is disposed at the upper end of the package 80 in which the IC chip 60 and the resonator element 1 are joined in the recess, and the package is formed by, for example, seam welding via a seal ring 89. 80. An internal space serving as a space for operating the resonator element 1 in the package 80 can be sealed and sealed in a reduced pressure space or an inert gas atmosphere.

  According to the oscillator 600 configured as described above, by providing the member 30, the first region and the second region are efficiently subjected to thermal relaxation, the thermal relaxation time is shortened, and the thermoelastic loss is suppressed. Since the resonator element 1 having a Q value is mounted, the oscillator 600 having a small size and stable oscillation characteristics can be provided.

(Fourth embodiment)
〔Electronics〕
The electronic device including the vibrator 500 according to the second embodiment including the resonator element 1 according to the first embodiment and the oscillator 600 according to the third embodiment is reduced in size and performance. It is possible.
For example, as a signal source of the mobile phone 200 as the electronic device shown in FIG. 11A or the mobile computer 300 as the electronic device shown in FIG. By mounting the vibrator 500 and the oscillator 600 including the above, the mobile phone 200 and the mobile computer 300 can be downsized and enhanced in function.
In addition to these mobile phones 200 and mobile computers 300, in small-sized communication equipment such as a portable information terminal such as a PDA (Personal Digital Assistant) or a global positioning system widely known as GPS (Global Positioning System). In recent years, there has been an increasing demand for miniaturization and thinning. Therefore, a resonator element having a small and stable vibration characteristic, and a vibrator 500 and an oscillator 600 using the resonator element are mounted. This makes it possible to reduce the size and performance of electronic devices.

  The resonator element described in the above embodiment can also be implemented as the following modifications.

(Modification)
In the resonator element 1 of the above-described embodiment, the member 30 is formed as a single-layer member 30 using a non-conductive material that has lower thermal efficiency than the crystal that is the material for forming the base 16 and the vibrating arms 18a, 18b, and 18c. The configuration. However, the present invention is not limited to this, and the member may be a laminated body having a plurality of layers. In addition, when the member is a member having a plurality of layers, the member may include a layer made of a conductive material such as metal.
FIG. 8 illustrates a modification of the resonator element in which a multi-layer member including a metal layer is formed. The same cross section as the DD ′ line cross section of FIG. 3F in the resonator element 1 of the above embodiment. It is a schematic sectional drawing which shows the cross section of one vibration arm among these. Note that, among the configurations of the resonator element (vibrating arm) of the present modified example, the same components as those in the above embodiment are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 8, the first electrode 20, the piezoelectric film 22, and the second electrode 26 are stacked in this order on one main surface (first main surface) of the vibrating arm 68 of the vibrating piece 50 of the present modification. An excitation electrode made of a body is formed.
Similarly to the vibrating piece 1 of the first embodiment, the first surface of the vibrating arm 68, the surface opposite to the first surface (second surface), and the first surface and the second surface A layer including an insulating base layer 135 and a metal layer 130 formed on the base layer 135 in a region (not shown) including the vicinity of the base between both side surfaces to be connected and the base of the vibrating arm 68. A structural member is formed.
Although not shown, the members (the base layer 135 and the metal layer 130) of the vibrating piece 50 of the present modification are also placed on the vibrating arm 68 in the same manner as the member 30 of the vibrating piece 1 of the first embodiment. A member formed on the vibration arm 68 so as to cover the base of the excitation electrode formed of the first electrode 20, the piezoelectric film 22, and the second electrode 26 and the base 16 of the vibration arm 68 up to the base. (Underlayer 135 and metal layer 130) are provided with a gap so as to be thermally independent.

In such a member made of the insulating base layer 135 and the metal layer 130, when the vibrating piece 50 bends and vibrates in the thickness direction (Z direction) of the vibrating arm 68, compressive stress or tension is applied to the first and second regions. When the temperature rises or falls due to stress, the metal layer 130 serves as a heat conduction path between the first region and the second region and contributes to shortening of the relaxation time. The material used for the metal layer 130 For example, the metal among the materials shown in FIG. 4, that is, silver (Ag), copper (Cu), gold (Au), aluminum (Al), molybdenum (Mo), chromium (Cr), titanium (Ti ), Platinum (Pt), and the like. In addition, the metal layer 130 is not limited to the single metal layer 130 of such a single metal, and the metal layer 130 may be formed by stacking a plurality of metal layers, or the metal layer 130 may be formed of a plurality of metal alloys. It is good also as composition to do.
In addition, as the insulating member material used as the base layer 135, a material conventionally used as an insulating film of an electronic circuit element can be applied. For example, silicon dioxide (SiO ₂ ) or silicon nitride (SiN) ) Etc. can be used. Among these, it is preferable to form the base layer 135 using silicon dioxide because it has an effect of improving the temperature characteristics of the resonator element 50. This is because when an insulating film is formed on the piezoelectric vibrating piece, in many insulating film materials, the frequency decreases when the ambient temperature rises, whereas when the insulating film is formed of silicon dioxide, This is because the frequency increases when the ambient temperature increases.

  According to the resonator element 50 of the present modified example, by interposing the insulating base layer 135, the metal layer 130 made of a metal material with a wide range of options can shorten the thermal relaxation time and suppress the decrease in the Q value. Therefore, the Q value of the small vibrating piece 50 can be improved at low cost.

  The embodiment of the present invention made by the inventor has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications are made without departing from the scope of the present invention. Is possible.

  For example, in the above embodiment, the vibration piece 1 having the three vibration arms 18a, 18b, and 18c has been described. The vibration piece of the present invention is not limited to this, and may be a strip-shaped so-called beam-type bending vibration piece, or a so-called tuning-fork type vibration piece having two vibration arms, or four or more vibration arms. Even if it is a vibration piece, the same effect as an above-mentioned embodiment and a modification can be acquired.

Further, in the vibrator 500 of the second embodiment and the oscillator 600 of the third embodiment, the resonator element 1 is mechanically joined to the packages 70 and 80 by the joining member 99, and further, a wire bonding method is used. And the resonator element 1 and the packages 70 and 80 are electrically connected by a bonding wire 95. Not limited to this, the external connection electrodes 26 a and 26 b of the resonator element 1 are provided on the second main surface side of the base portion 16, and the external connection electrodes 26 a and 26 b and the corresponding resonator element connection terminals 76 of the packages 70 and 80 are provided. 88 can be configured to be joined by a conductive joining member such as a silver paste. In this case, mechanical joining and electrical connection of the resonator element 1 to the packages 70 and 80 can be realized at the same time.
In the oscillator 600 of the third embodiment, the configuration in which the IC chip 60 is connected to the package 80 by the bonding wire 95 using the wire bonding method has been described. However, the present invention is not limited to this, and an electronic component such as the IC chip 60 may be face-down bonded using another mounting method, for example, a bonding member such as a metal bump or a conductive adhesive.

  DESCRIPTION OF SYMBOLS 1,50 ... Vibrating piece, 10 ... 2nd surface, 12 ... 1st surface, 16,102 ... Base, 18a-18c, 68, 103,104 ... Vibrating arm, 20 ... 1st electrode, 22 ... Piezoelectric film, 24 ... Opening part, 26 ... Second electrode, 26a, 26b ... External connection electrode, 30 ... Member, 35 ... Electrode pad, 60 ... IC chip as circuit element, 70,80 ... Package, 71,81 ... First layer substrate 72, 82 ... second layer substrate, 73, 83 ... third layer substrate, 75 ... external mounting terminal, 76, 88 ... vibrating piece connection terminal, 79 ... seal ring, 84 ... fourth layer substrate, 86 ... die pad, 87 ... IC connection terminal, 91, 92 ... lid, 95 ... bonding wire, 98 ... brazing material, 99 ... bonding member, 100 ... crystal vibrating piece (as a conventional vibrating piece), 106, 107 ... groove or hole, 110 , 112 ... 1st region , 111, 113 ... second region, 130 ... metal layer, 135 ... base layer, 200 ... mobile phone as an electronic apparatus, 300 ... mobile computer as an electronic device, 500 ... transducer, 600 ... oscillator.

Claims (9)

The base,
A vibration arm extending from one end of the base and provided with a drive electrode on the first surface;
A first region in which compressive stress or tensile stress acts on the first surface by vibration of the vibrating arm;
When compressive stress is applied to the first region on the second surface connected to the first surface by the side surface orthogonal to the first surface, tensile stress is applied to the first region, and tensile stress is applied to the first region. Has a second region in which compression stress acts,
The side surface connecting the first region and the second region, and the first region and the second region is made of a material having a lower thermal resistance than at least the material forming the base and the vibrating arm. A vibrating piece covered with a member. The resonator element according to claim 1,
The member consists of one layer or a plurality of layers,
A vibrating piece, wherein at least a part or all of the member in contact with the first surface, the second surface, and the side surface is made of a non-conductive material. The resonator element according to claim 2,
The resonator element, wherein the non-conductive material is diamond. The resonator element according to claim 2,
The vibration characterized in that the member includes an insulating underlayer formed on the first surface, the second surface, and the side surface, and a metal layer formed on the underlayer. Fragment.   5. The vibrating piece according to claim 1, wherein the base and the vibrating arm are formed using a piezoelectric material. The resonator element according to claim 5,
A resonator element, wherein crystal is used as the piezoelectric material.   A vibrator comprising: the resonator element according to claim 1; and a package that accommodates the resonator element.   A vibration piece according to any one of claims 1 to 6, a circuit element including an oscillation circuit that oscillates the vibration piece, and a package that houses the vibration piece and the circuit element. Oscillator.   An electronic device equipped with the vibrator according to claim 7 or the oscillator according to claim 8.

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