JP5982898B2 - Vibration element, vibrator, electronic device, oscillator, and electronic device - Google Patents

Description

  The present invention relates to a vibration element in a thickness vibration mode, and particularly relates to a vibration element, a vibrator, an electronic device, an oscillator, and an electronic apparatus having a so-called mesa structure.

AT-cut quartz resonators are used in various fields such as electronic equipment because the vibration mode is thickness-shear vibration, and they exhibit a cubic curve that is suitable for miniaturization and higher frequency and has excellent frequency-temperature characteristics. .
In Patent Literature 1 and Patent Literature 2, the frequency of the quartz resonator element is f, the length of the long side (X axis) of the quartz substrate is X, the thickness of the mesa portion (vibrating portion) is t, and the long side of the mesa portion is When the length is Mx, the length of the long side of the excitation electrode is Ex, and the wavelength of the bending vibration generated in the long side direction of the quartz substrate is λ, the following four formulas:
λ / 2 = (1.332 / f) −0.0024
(Mx−Ex) / 2 = λ / 2
Mx / 2 = (n / 2 + 1/4) λ (where n is an integer)
X ≧ 20t
It is disclosed that the coupling between the thickness shear vibration and the bending vibration can be suppressed by setting the parameters f, X, Mx, and Ex so as to satisfy the above. The bending displacement component is reduced when the position of the edge of the vibration part and the edge of the excitation electrode is set so as to coincide with the position of the antinode of the displacement of the bending vibration. It is disclosed that a certain bending vibration can be suppressed.

  Patent Document 3 proposes a mesa type vibration element that increases frequency variable sensitivity and suppresses unnecessary vibration. Generally, in the vibration element, the equivalent series capacitance C1 increases as the excitation electrode increases, and the frequency variable sensitivity can be increased. It is disclosed that a mesa type vibration element with a large excitation electrode can oscillate easily and can widen the frequency change with respect to the load capacity.

Patent Document 4 discloses a mesa-type piezoelectric vibration element. The length of the long side of the quartz substrate is X, the depth of the stepped portion (the height of the mesa portion) is Md, the plate thickness of the vibrating portion is t, and the ratio of the depth of the stepped portion Md to the plate thickness t is y ( %), Y is
y = −1.32 × (X / t) +42.87
y ≦ 30
And the ratio of the length X of the long side to the plate thickness t of the vibrating portion of the quartz substrate, that is, the side ratio X / t is 30 or less, the electrical characteristics of the piezoelectric vibrating element are deteriorated. It is disclosed that CI can be reduced without incurring.

JP 2006-340023 A JP 2007-053820 A JP 2008-306594 A JP 2007-124441 A

However, recently, a further smaller vibrator having a container size has been demanded. The X-side ratio (ratio X / t of the long side X to the thickness t) of the vibration element having a mesa structure housed in the small container is 20 or less. Even if the means as disclosed in the prior art is applied to such a small vibrator, the high-order vibration of the contour system is superimposed on the thickness shear vibration, and smooth frequency temperature characteristics cannot be obtained. There is a problem that CI (crystal impedance) cannot be realized.
The present invention has been made in order to solve the above-described problems, and is a thickness-shear mode vibration element having a long side in the X-axis direction, and a smooth frequency-temperature characteristic of a vibration element having a small X-side ratio, and CI. An object of the present invention is to provide a mesa type vibration element that can reduce the above.

  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 vibration element according to the present invention is excited by thickness shear vibration, and is provided on a first convex portion provided on one main surface, on the other main surface on the back side with respect to the one main surface. At least two or more steps provided at the ends of the vibrating portion including the second protruding portion, the first protruding portion, and the second protruding portion that intersect the vibration direction of the thickness shear vibration. A substrate including an edge portion and an outer edge portion disposed along an outer edge of the vibrating portion and having a thickness smaller than a thickness of the vibrating portion; a first excitation electrode provided on a surface of the first convex portion; A second excitation electrode provided on the surface of the second convex portion, and when the number of steps of the step edge is represented by a positive integer i of 2 or more, the thickness shear vibration of the step edge of the i-th step along the length along the vibration direction Mx _i, the vibration direction of the thickness shear vibration of the step edge of the outermost Mx is the length along the direction perpendicular to the vibration direction of the thickness-shear vibration of the first step edge, and Mz is the length along the vibration direction of the thickness-slip vibration of the excitation electrode. Ex, where Ez is the length of the excitation electrode along the direction perpendicular to the vibration direction of the thickness shear vibration, and λ is the wavelength of the flexural vibration that vibrates in the vibration direction of the thickness shear vibration,
−0.2 <((Mx _i−1 −Mx _i ) / 2−nλ / 2) / (λ / 2) <0.2 (1)
−0.2 <((Ex−Mx) −kλ / 2) / (λ / 2) <0.2 (2)
It is a vibration element characterized by satisfying. However, n is a positive integer and k is an integer.

  According to this configuration, the vibrating portion has a mesa structure having at least two stepped portions so that the thickness of the vibrating portion gradually decreases toward the outer edge of the entire outer peripheral edge, and each stepped portion. And the length of the excitation electrode are set based on the equations (1) and (2), so that the bending vibration is suppressed, and the excitation electrode cancels the electric charge of the bending vibration to be picked up. The CI temperature characteristic has an effect that a smooth characteristic can be obtained. In addition, by forming the entire outer peripheral edge of the vibration part to have a step structure of at least two steps, vibration energy is confined in the excitation part, and a vibration element having a small CI can be obtained.

  [Application Example 2] Further, in the vibration element described in Application Example 1, the step number i of the stepped portion is 2, the positive integer n is 1, the integer k is -1, and the Ex and the Mx The vibration element is characterized in that Ex <Mx.

  According to this configuration, the length of each stepped portion and the size of the excitation electrode satisfy the expressions (1) and (2), the number of steps of the stepped portion is two, and the size of the excitation electrode is the outermost ( Since it is set shorter than the length of the uppermost step), there is an effect that smooth frequency temperature characteristics and CI characteristics can be obtained. Furthermore, there is an effect that the equivalent inductance of the vibration element can be increased.

  [Application Example 3] Further, in the vibration element according to Application Example 1, the step number i of the stepped portion is 2, the positive integer n is 1, the integer k is 2, and the Ex, the Mx, The vibration element is characterized in that there is a relationship of Mx <Ex.

  According to this configuration, the length of each stepped portion and the size of the excitation electrode satisfy the expressions (1) and (2), the number of steps of the stepped portion is two, and the size of the excitation electrode is the outermost ( Since it is set larger than the length of the uppermost step), there is an effect that smooth frequency temperature characteristics and CI characteristics can be obtained. Furthermore, there is an effect that the equivalent inductance of the vibration element can be reduced. In addition, since most of the charges generated by the vibration can be picked up, there is an effect that the capacitance ratio of the vibration element can be reduced.

  Application Example 4 In the vibration element according to Application Example 1, the step number i of the stepped portion is 2, the positive integer n is 2, the integer k is 1, and the Ex and the Mx The vibration element is characterized in that there is a relationship of Mx <Ex.

  According to this configuration, the length of each stepped portion and the size of the excitation electrode satisfy the expressions (1) and (2), the number of steps of the stepped portion is two, and the size of the excitation electrode is the outermost ( Since it is set larger than the length of the uppermost step), there is an effect that smooth frequency temperature characteristics and CI characteristics can be obtained. Furthermore, there is an effect that the shape of the vibration displacement distribution is smoothed and CI temperature characteristics with little CI dip are obtained.

  [Application Example 5] Further, in the application example 1, in the application example 1, the step number i of the stepped portion is 3, the positive integer n is 1, the integer k is 3, and the Ex and the maximum of the vibrating portion are used. The vibration element is characterized in that there is a relationship of Mx <Ex between the upper principal surface and the length Mx along the vibration direction of the thickness shear vibration.

  According to this configuration, the length of each stepped portion and the size of the excitation electrode satisfy the expressions (1) and (2), the number of steps of the stepped portion is two, and the size of the excitation electrode is the outermost ( Since it is set larger than the length of the uppermost step), there is an effect that smooth frequency temperature characteristics and CI characteristics can be obtained. Furthermore, since the number of steps of the step portion is three, the vibration displacement distribution becomes steeper and the influence of the support is reduced, so that the CI of the vibration element can be further reduced.

  [Application Example 6] Further, in the application example 1, in the application example 1, the step number i of the stepped portion is 3, the positive integer n is 1, the integer k is 2, and the Ex and the maximum of the vibrating portion. The vibration element is characterized in that there is a relationship of Mx <Ex between Mx along the vibration direction of the thickness-shear vibration of the upper main surface.

  According to this configuration, the length of each stepped portion and the size of the excitation electrode satisfy the expressions (1) and (2), the number of steps of the stepped portion is two, and the size of the excitation electrode is the outermost ( Since it is set larger than the length of the uppermost step), there is an effect that smooth frequency temperature characteristics and CI characteristics can be obtained. Furthermore, since the number of steps of the stepped portion is three, the vibration displacement distribution becomes steeper and the influence of the support becomes smaller, so the effect of reducing the CI of the vibrating element and the size of the electrode can be adjusted to the specifications. There is an effect that can be combined.

  Application Example 7 In addition, the vibration element according to Application Example 1, wherein the substrate is a rotating Y-cut substrate, and the vibration unit has a side along the X-axis direction as a long side and extends along the Z′-axis direction. The vibration element is characterized in that the short side is a short side.

  According to this configuration, since the vibration substrate is formed of a quartz substrate, the frequency temperature characteristic and the CI temperature characteristic can be obtained smoothly, and the vibration element having a small QA and a large Q value of the vibration element can be obtained. There is an effect that it is obtained.

  [Application Example 8] Further, in any one of Application Examples 1 to 7, the vibration element satisfies a relationship of 0.6 ≦ Mz / Z ≦ 0.8 when Ez <Mz, and when Ez> Mz. The vibration element satisfies the relationship of 0.5 ≦ Mz / Z ≦ 0.7.

  According to this configuration, in addition to the above effects, CI can be reduced, and there is an effect that a vibration element having no coupling with unnecessary vibration such as bending vibration can be obtained.

  Application Example 9 A vibrator according to the present invention includes the vibration element according to any one of Application Examples 1 to 8, and a container that houses the vibration element. It is.

  According to this configuration, there is an effect that a small vibrator having a small CI value, that is, a large Q value, little secular change, smooth frequency temperature characteristics, and CI characteristics can be obtained by suppressing bending vibration. .

  Application Example 10 An electronic device according to the present invention includes the vibration element according to any one of application examples 1 to 8, an electronic element, and a container that accommodates the vibration element and the electronic element. There is an electronic device characterized by this.

  According to this configuration, the small vibration element having a small CI according to the present invention is provided, and by combining with the electronic element to be used, various electronic devices can be configured in accordance with customer specifications. .

  Application Example 11 An electronic device according to the present invention is an electronic device according to Application Example 10, wherein the electronic element is at least one of a thermistor, a capacitor, a reactance element, and a semiconductor element.

  According to this configuration, the combination of the small-sized vibration element having a small CI according to the present invention and the above-described electronic element makes it possible to configure a temperature-compensated vibration element, a vibration element having a wide variable range, an oscillator, and the like. is there.

  Application Example 12 An oscillator according to the present invention includes the vibrator according to Application Example 9 and an oscillation circuit that drives the vibrator.

  According to this configuration, it is possible to reduce the size of the oscillator and to realize an oscillator with low power consumption and excellent frequency temperature characteristics.

  Application Example 13 An electronic device according to the present invention is an electronic device including the vibration element according to any one of Application Examples 1 to 8.

  According to this configuration, it is possible to reduce the size of the electronic device and to obtain an electronic device having excellent frequency stability, frequency temperature characteristics, and impact resistance.

It is the schematic which shows the structure of the vibration element 1 of embodiment which concerns on this invention, (a) is a top view, (b) is QQ sectional drawing of (a), (c) is (a ) PP sectional view. The figure which shows the relationship between the new orthogonal axis | shaft X, Y ', Z' axis | shaft formed by theta rotation of the crystal axes X, Y, and Z of quartz around the X-axis, and an AT cut quartz crystal substrate. FIG. 3 is a diagram in which isobaric lines formed by connecting points having equal vibration displacement energy on a plane showing the configuration of the vibration element 1 are overwritten. The structure of the vibration element 1s used in the experiment is shown. (A) is a plan view, (b) is a QQ sectional view of (a), and (c) is a PP sectional view of (a). . The figure which shows the relationship between electrode area S and CI. The figure which shows the distance (DELTA) X from an electrode edge part to a support part, and CI. It is a figure which shows the vibration element 2 of 2nd Embodiment, (a) is a top view, (b) is QQ sectional drawing of (a), (c) is P-- of (a). P sectional drawing. It is a figure which shows the vibration element 3 of 3rd Embodiment, (a) is a top view, (b) is QQ sectional drawing of (a), (c) is P-- of (a). P sectional drawing. It is a figure which shows the vibration element 4 of 4th Embodiment, (a) is a top view, (b) is QQ sectional drawing of (a), (c) is P-- of (a). P sectional drawing. It is a figure which shows the vibration element 5 of 5th Embodiment, (a) is a top view, (b) is QQ sectional drawing of (a), (c) is P-- of (a). P sectional drawing. (A) thru | or (d) is sectional drawing which shows typically the manufacturing method of the vibration element of this embodiment. (A) thru | or (d) is sectional drawing which shows typically the manufacturing method of the vibration element of this embodiment. Sectional drawing which shows the structure of a vibrator | oscillator. (A), (b) is sectional drawing which shows the structure of an electronic device, respectively. Sectional drawing which shows the structure of an oscillator. FIG. 6 is a plan view showing a configuration of a modification of the vibration element 1 shown in FIG. 1. FIG. 6 is a plan view showing a configuration of a modification of the vibration element 1 shown in FIG. 1. 1 is a schematic plan view of an electronic device according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a configuration of a vibration element 1 according to an embodiment of the present invention. 1A is a plan view of the resonator element 1, FIG. 1B is a cross-sectional view taken along the line QQ in FIG. 1A, and FIG. 1C is a cross-sectional view taken along the line P-P in FIG. .
The vibration element 1 according to the present invention includes a vibration substrate 10, excitation electrodes 20 a and 20 b disposed opposite to both main surfaces of the vibration substrate 10, and one end portion of the vibration substrate 10 from the excitation electrodes 20 a and 20 b. The vibrating element includes lead electrodes 22a and 22b extending in the direction and electrode pads 24a and 24b electrically connected to the lead electrodes 22a and 22b and formed at two corners of the vibration substrate 10, respectively. .
The vibration substrate 10 includes a vibration part 14 having a maximum thickness, and an outer edge part 12 that is thinner than the vibration part 14 and protrudes in a bowl shape from a middle part in the thickness direction of the entire circumferential side surface of the vibration part 14. ,have. The vibration substrate 10 is formed symmetrically with respect to the center line in the thickness direction from the point of vibration balance. In other words, it is formed symmetrically with respect to a plane passing through the center in the thickness direction and parallel to the main surface.

The vibration part 14 includes at least two step edges so that the thickness of the vibration part 14 gradually decreases stepwise toward the outer edge 12 on the entire outer periphery. The vibration element 1 according to the embodiment shown in FIG. 1 has step edge portions each formed of two steps on the front and back surfaces of the outer peripheral edge of the vibration portion 14. The step edge portion includes step edge portions 14c and 14d extending parallel to the Z′-axis direction and step edge portions 14a and 14b extending parallel to the X-axis direction. That is, the vibration substrate 10 includes a vibration portion 14 that is a thick portion (including a step edge portion) in which the center portion of the substrate protrudes in a direction orthogonal to both main surfaces, and the thickness of the entire peripheral side surface of the vibration portion 14. It has a so-called mesa structure having an outer edge portion 12 protruding in the main surface direction from the middle portion in the vertical direction.
The vibration part 14 is a main vibration area located at the center of the vibration substrate 10, and the outer edge part 12 which is thinner than the vibration part 14 and formed on the entire circumferential side surface of the vibration part 14 is a sub vibration area. That is, the vibration region extends over the vibration part 14 and a part of the outer edge part 12 as described later.

  Excitation electrodes 20a and 20b (hereinafter, represented by 20a) are formed in a part of the vibration part 14 in the embodiment shown in FIG. The excitation electrode 20a, the extraction electrodes 22a and 22b (hereinafter represented by 22a), and the electrode pads 24a and 24b (hereinafter represented by 24a) are formed on both surfaces of the vibration substrate 10 by sputtering or vacuum deposition. Metal films such as chromium (Cr) and gold (Au) are formed in this order. A vibrating element is configured by forming an excitation electrode 20a, an extraction electrode 22a, and an electrode pad 24a having a predetermined shape on the formed metal thin film by a photolithography technique. When an alternating voltage is applied to each excitation electrode 20a, the vibration element 1 is excited at a specific vibration frequency.

  A case where a quartz substrate is used as the vibration substrate 10 will be described. A piezoelectric material such as quartz belongs to the trigonal system and has crystal axes X, Y, and Z orthogonal to each other as shown in FIG. The X axis, the Y axis, and the Z axis are referred to as an electric axis, a mechanical axis, and an optical axis, respectively. The rotated Y-cut substrate is a flat plate cut out from crystal along a plane obtained by rotating the XZ plane about the X axis by an angle θ. For example, in the case of the AT-cut quartz substrate 10, the angle θ is approximately 35 ° 15 ′. The Y-axis and the Z-axis are also rotated around the X-axis by the angle [theta] to be a Y'-axis and a Z'-axis, respectively. Accordingly, the rotating Y-cut substrate has orthogonal coordinate axes X, Y ', and Z'. The rotating Y-cut substrate has a thickness direction of the Y ′ axis, an XZ ′ plane (a plane including the X axis and the Z ′ axis) orthogonal to the Y ′ axis is a main surface, and a thickness shear vibration is a main vibration. Excited.

That is, as shown in FIG. 2, the quartz substrate 10 is centered on the X axis of an orthogonal coordinate system composed of the X axis (electric axis), the Y axis (mechanical axis), and the Z axis (optical axis), and the Z axis is the Y axis. The axis tilted in the −Y direction is the Z ′ axis, the Y axis is the Y ′ axis is the axis tilted in the + Z direction of the Z axis, and is composed of surfaces parallel to the X and Z ′ axes. It consists of an AT-cut quartz substrate with the thickness in the parallel direction.
In the embodiment shown in FIG. 1, the vibration substrate 10 has a direction parallel to the Y axis (hereinafter referred to as “Y ′ axis direction”) and a direction parallel to the X axis (hereinafter referred to as “X axis direction”). And a rectangular shape having a short side in a direction parallel to the Z ′ axis (hereinafter referred to as “Z ′ axis direction”). Here, the lengths of the long side and the short side are X and Z, respectively. The vibration substrate 10 has a thick vibration part 14 positioned substantially at the center part, and an outer edge part 12 projecting like a bowl from the center part of the entire circumferential side surface of the vibration part 14.

As shown in the embodiment of FIG. 1, the vibration portion 14 is surrounded by the outer edge portion 12 at the center of the entire circumferential side surface, and has a thickness t that is thicker than the thickness t ′ of the outer edge portion 12 in the Y′-axis direction. Have That is, the vibration part 14 protrudes in the Y′-axis direction with respect to the outer edge part 12 as shown in FIGS. In the example of FIG. 1, the vibrating portion 14 protrudes on the + Y ′ axis side and the −Y ′ axis side with respect to the outer edge portion 12. For example, the vibrating portion 14 has a point (not shown) that is a center of symmetry, and can have a shape that is point-symmetric with respect to the center point.
As shown in FIG. 1, the vibrating section 14 has a rectangular shape with the long side in the X-axis direction and the short side in the Z′-axis direction. The vibration unit 14 includes a thickest first portion 15 and a second portion 16 having a thickness smaller than the first portion 15. The first portion 15, as shown in FIG. 1, (in the figure 1 (b) indicated by _Mx 2/2) in length parallel to the X axis Mx ₂ having a rectangular shape with the long side of. The second portion 16 is formed around the entire side surface of the first portion 15, and has a length Mx ₁ (in FIG. 1B) parallel to the X axis, which is a shape obtained by adding the first portion 15 and the second portion 16. Has a rectangular shape with a long side of Mx _1/2 ) and a short side of a length Mz parallel to the Z ′ axis. That is, the vibration substrate 10 is a two-stage mesa substrate.
Due to such a configuration, the vibrating portion 14 has a structure including step edge portions 14a and 14b extending in the X-axis direction and step edge portions 14c and 14d extending in the Z′-axis direction. In the embodiment shown in FIG. 1, of the step edges 14a and 14b, the step edge 14a is a step edge on the + Z ′ axis side, and the step edge 14b is a step edge on the −Z ′ axis side. Of the step edges 14c and 14d, the step edge 14c is a step edge on the −X axis side, and the step edge 14d is a step edge on the + X axis side.

As shown in FIG. 1B, the step edge 14d extending in the Z′-axis direction is formed so as to protrude from the outer edge 12 on the + Y′-axis side and the −Y′-axis side, respectively. The same applies to the step edge portions 14a, 14b, and 14c.
The steps of the step edge portions 14c and 14d of the vibration portion 14 are formed by differences in thickness between the first portion 15 and the second portion 16, and the surface parallel to the Y′Z ′ plane of the first portion 15 and the second portion 15 are formed. The portion 16 is constituted by a plane parallel to the XZ ′ plane and a plane parallel to the Y′Z ′ plane of the second portion 16. Similarly, the steps of the step edge portions 14 a and 14 b of the vibration unit 14 are formed by differences in thickness between the first portion 15 and the second portion 16. In the illustrated example, the step edge portions 14 a and 14 b are provided on the plane parallel to the XY ′ plane of the first portion 15, the plane parallel to the XZ ′ plane of the second portion 16, and the XY ′ plane of the second portion 16. And parallel surfaces. Thus, the vibration part 14 has two types of first parts and second parts 15 and 16 having different thicknesses, and it can be said that the vibration element 1 has a two-stage mesa structure. The vibration unit 14 can vibrate with thickness shear vibration as the main vibration.
As described above, since the vibration part 14 has the two-stage mesa structure, when the thickness shear vibration is excited, the vibration energy is confined in the vibration part 14 and can have a so-called confinement effect. .

  FIG. 3 shows an isotropic force formed by connecting the points where the vibration displacement energy (the product of the square of the vibration displacement and the mass at the position) is equal when the vibration element 1 is excited on the plan view of the vibration element 1. The line distribution is indicated by a one-dot chain line. The energy level of the contour lines located at the center is the highest, and the energy level of the contour lines located outside is lower. In the example of the resonator element 1 shown in FIG. 3, the vibrating portion 14 has a rectangular shape that is long in the X-axis direction. Therefore, the contour lines have a long major axis in the X-axis direction and a short minor axis in the Z′-axis direction. Oval shape. The magnitude of the vibration displacement is maximum at the center portion of the vibration portion 14 and decreases as the distance from the center portion increases. That is, both the X-axis direction and the Z′-axis direction are distributed almost on the cosine on the excitation electrode 20a, and are attenuated exponentially on the quartz substrate without the excitation electrode 20a. Since the vibration region extends in an elliptical shape in the vibration portion 14 and the outer edge portion 12 connected to the vibration portion 14, the vibration element having the excitation electrode only on the vibration portion 14 is excited on the quartz substrate 10. Cannot be collected (cannot be picked up). The vibration element 1 in which the excitation electrode 20a is arranged on at least a part of the outer edge part 12 connected to the vibration part 14 and is configured to collect charges excited by the quartz substrate 10 reduces the capacitance ratio of the vibration element. It is possible to widen the frequency variable range when configuring the oscillator.

  4A is a plan view of the resonator element 1s used in the experiment, FIG. 4B is a QQ cross-sectional view of FIG. 4A, and FIG. It is -P sectional drawing. As shown in FIGS. 4B and 4C, the vibration element 1 s includes the vibration part 14 having two steps in the X-axis direction and one step in the Z′-axis direction of the outer peripheral edge, and all of the vibration parts 14. At least a vibration substrate 10 having a thin outer edge portion 12 projecting like a bowl from a middle portion in the thickness direction of the peripheral side surface, the entire area on both main surfaces of the vibration portion 14, and the outer edge portion 12 connected to the vibration portion 14. Excitation electrodes 20a and 20b that are partially opposed to each other, extraction electrodes 22a and 22b extending from the excitation electrodes 20a and 20b toward the end of the vibration substrate 10, and end portions of the extraction electrodes 22a and 22b. In addition, electrode pads 24 a and 24 b formed respectively at two corners of the vibration substrate 10 are roughly provided. When an alternating voltage is applied to the excitation electrodes 20 a and 20 b, the vibration element 1 s is excited at a specific vibration frequency, and the vibration region straddles the vibration portion 14 and a part of the outer edge portion 12.

  FIG. 5 shows the vibration element shown in FIG. 4 when the area S of the excitation electrode 20a formed on the vibration substrate 10 having a mesa structure with a dimension X in the X-axis direction of 1100 μm and a thickness t of 65 μm is changed. It is the curve which measured CI of the vibration element 1s. The horizontal axis represents the area S of the excitation electrode 20a, and the vertical axis represents the CI value. From this experiment, it can be seen that the CI of the crystal resonator is large when the area S is small, the CI is small as the area S is large, and the CI is large when the area S is further increased. That is, it has been experimentally found that there is an electrode area S that minimizes CI when the dimensions of the quartz substrate are determined.

  Furthermore, experiments were repeated to examine the relationship between the dimension of the vibration substrate 10 in the X-axis direction and the dimension of the excitation electrode 20a. As shown in FIG. 4, the X-axis direction dimension of the vibration substrate 10 is X, and the X-axis direction dimension of the excitation electrode 20a is Le. In the example of FIG. 4, the excitation electrode 20 a straddles the entire area of the vibrating portion 14 and a part of the outer edge portion 12. The size of the support region 26 (the region in which the vibration substrate 10 is fixed to the support member using a conductive adhesive) provided in each electrode pad 24a of the vibration substrate 10 is Ad, and the vibration substrate 10 in the support region 26 is provided. ΔX is the distance between the center-side end of the electrode and the left-side end of the excitation electrode 20a facing the support region 26 in the figure.

FIG. 6 is a diagram illustrating the relationship between the distance ΔX and the CI of the vibrator 1s. When the distance ΔX is small, the CI is large. As the distance ΔX is increased, the CI is decreased. When the distance ΔX is further increased, the CI is increased.
The ΔX-CI curve in FIG. 6 was assumed to be composed of curves showing two different mechanisms of properties, that is, a curve A that monotonously decreases and a curve B that monotonously increases. The CI represented by the curve A decreases as the distance ΔX increases. This mechanism is considered as follows. The vibration displacement distribution on the excitation electrode 20a is substantially cosine-like, and the vibration displacement of the outer edge portion 12 without the excitation electrode 20a decreases exponentially with the distance from the end of the excitation electrode 20a as a variable. The support area 26 is a part for applying a conductive adhesive or the like to this area and fixing the vibration substrate 10 to a support member such as a package. The vibration displacement energy that is rapidly decreasing from the end of the excitation electrode 20a reaches the support region 26, and the leaked vibration energy is absorbed by the adhesive applied to the support region 26 and dissipated. That is, the greater the distance ΔX, the smaller the vibration energy that reaches the end of the support region 26 (the right end in the drawing), and the less the energy that leaks. As a result, the Q value of the crystal resonator is large and the CI is small.
On the other hand, when the distance ΔX is small, the vibration energy reaching the end of the support region 26 (the right end in the drawing) is large, the leaking energy is large, and the Q value is small. For this reason, CI becomes large. CI is a curve A that monotonously decreases as the distance ΔX increases.

On the other hand, the curve B is considered as follows. It is well known that the Q value of a crystal resonator determined only by internal loss decreases in inverse proportion to the frequency f. When the frequency range is not so large, in the vibration substrate (quartz substrate) 10 having a dimension in the X-axis direction of about 1.1 mm, when the shape dimension is determined, the Q value is almost the same unless the dimensions of the excitation electrode are significantly changed. It is considered constant. It is also well known that the equivalent series inductance (motional inductance) L1 of the vibrator is proportional to the cube of the thickness t of the vibration substrate and inversely proportional to the electrode area.
As shown in FIG. 4, the excitation electrode 20 a is arranged symmetrically with respect to a center line Cn corresponding to the longitudinal center of the vibration part 14. Here, consider a case where it is ideally supported and fixed to such an extent that the influence of the adhesive fixing the vibration substrate 10 can be ignored. As the distance ΔX is smaller, that is, as the dimension Le of the excitation electrode 20 is larger, the charges excited on the vibration substrate 10 can be collected. Since the vibration displacement is distributed in a cosine shape with the center of the vibration portion 14 as the apex, the charge collection efficiency at the end of the excitation electrode 20a is deteriorated. Therefore, the excitation electrode 20a is not necessarily large.

The capacitance ratio γ, which is the ratio C0 / C1 between the equivalent series capacitance C1 determined according to the size of the excitation electrode 20a and the capacitance C0 determined in proportion to the size of the excitation electrode 20a, is the size of the excitation electrode 20a. There is a size of the excitation electrode 20a that minimizes the capacitance ratio γ. Since the equivalent series inductance L1 and the equivalent series capacitance C1 have a relationship of ω ₀ ² = 1 / (L1 · C1), the series inductance L1 is reduced when the dimension Le of the excitation electrode 20a is increased. When the Q value is substantially constant, the CI of the vibrator becomes small. That is, when the excitation electrode 20a is increased (the dimension Le is increased), that is, when ΔX is decreased, the CI is decreased.

However, since the vibration displacement is reduced at the periphery of the outer edge portion 12, the electric charge excited at that portion is small, and it is not efficient to provide an electrode there. It is also necessary to consider leakage from the support / fixing part. As the distance ΔX increases, the dimension Le of the excitation electrode 20 decreases, but there is a dimension Le of the excitation electrode 20a that collects charges excited on the quartz substrate 10 most efficiently. That is, there is a dimension Le that minimizes the capacity ratio γ. Further, as the distance ΔX increases, the dimension Le decreases and the series inductance L1 increases. If the Q value is substantially constant, this corresponds to an increase in CI. Therefore, as shown by the monotonous increase curve of curve B in FIG. 6, it can be explained that the CI increases as the distance ΔX increases.
That is, when the dimensions of the vibration substrate 10 are determined, focusing on the CI of the vibrator, the distance ΔX from the support region 26 has a range in which the CI is reduced. From FIG. 6, when CI is 68Ω, the range of ΔX is 0.04 mm ≦ ΔX ≦ 0.06 mm. This ΔX range was tested in the range of 14 ≦ X / t ≦ 18 as the X side ratio X / t. The same was true for X / t ≦ 14.

Further, as the vibration element 1 s having a two-stage mesa structure, the dimension in the Z′-axis direction (short side dimension) of the vibration substrate 10 is Z, the short side dimension of the vibration part 14 is Mz, and the thickness of the vibration part 14 When (the thickness of the first portion 15 of the vibrating portion 14) is t, it is preferable to satisfy the relationship of the following formula (1).
8 ≦ Z / t ≦ 11 and 0.6 ≦ Mz / Z ≦ 0.8 (1)

As a result, the coupling between the thickness shear vibration and the unnecessary mode such as the contour vibration (bending vibration) can be suppressed, and the CI can be reduced and the frequency temperature characteristic can be improved. Such coupling between the thickness shear vibration and the contour vibration is generally difficult to suppress as the area of the vibration substrate is smaller. Therefore, for example, in the case of a small vibration element that satisfies the relationship of the following equation (2) when the dimension (long side dimension) in the X-axis direction of the vibration substrate 10 is X, the relationship of the above equation (1) is satisfied. If it is designed so as to satisfy simultaneously, the coupling between the thickness shear vibration and the contour vibration can be suppressed more remarkably.
X / t ≦ 18 (2)

As shown in FIGS. 1B and 1C, the dimensions of each part of the vibration substrate 10 are set as follows. The length of the long side direction (X-axis direction) of the vibration substrate 10 is X, the length of the short side direction (Z′-axis direction) is Z, the length of the vibration part 14 in the Z′-axis direction is Mz, and the vibration part 14 The thickness of the outer edge 12 is t ′, the length of the first portion 15 of the vibrating portion 14 is Mx ₂ , and the first portion 15 and the second portion are added in the X-axis direction. The length is Mx ₁ , the length of the excitation electrode 20a in the X-axis direction is Ex, the amount of excavation at the step portion between the vibration portion 14 and the outer edge portion 12 (height of the vibration portion 14) is Md / 2, and the vibration portion 14 Let y be the ratio of the trench amount Md to the thickness t, and λ be the wavelength of bending vibration that occurs in the long side direction (X-axis method) of the vibration substrate 10. In FIG. 1B, the length of the right half in the figure with respect to the center line C of the vibration part 14 is displayed.

It is known that thickness vibration, which is the main vibration, is excited on the vibration substrate 10, but at the same time bending vibration is superimposed. The excitation electrode is set so that the amplitude of the bending vibration becomes “antinode” at each of the edge of the excitation electrode 20a, the edge of the first portion 15 of the vibration portion 14, and the edge of the second portion 16 of the embodiment of FIG. By setting 20a and the step edge portion 14d (14c), the amplitude of the bending vibration at each edge can be suppressed to the minimum. In other words, it can be expressed by the following equation.
(Mx ₁ -Mx ₂ ) / 2 = nλ / 2 (3)
(Ex−Mx ₂ ) = kλ / 2 (4)
Set each parameter to satisfy. However, n is a positive integer and k is an integer. In the embodiment shown in FIG. 1, a case where n = 1 and k = −1 is shown. Equation (4) is based on the length Mx of the first portion 15 of the vibrating portion 14 in the X-axis direction (Mx _{2 in} FIG. 1, the length of the outermost step in the X-axis direction) as a reference. When the length Ex in the X-axis direction is smaller than Mx, a sign “−” is attached, and when it is larger than Mx, a sign “+” is attached.
Here, in consideration of manufacturing variations, the influence on the characteristics of the vibration element 1 is small, and the following expression is obtained as an allowable range.
−0.2 <((Mx ₁ −Mx ₂ ) / 2−nλ / 2) / (λ / 2) <0.2 (5)
−0.2 <((Ex−Mx ₂ ) −kλ / 2) / (λ / 2) <0.2 (6)
The ratio of the moat amount Md to the thickness t is set as in the prior art.

In addition, as shown in FIG. 1C, the mesa-type vibration element 1 has a Z-axis dimension (short side dimension) of the vibration substrate 10 as Z and a short side dimension of the vibration unit 14 as Mz. When the length in the Z′-axis direction of the excitation electrode 20a (20b) is Ez and the thickness of the vibration part 14 is t, it is preferable that the relationship of the following formula (7) is satisfied.
In the case of Ez <Mz, 0.6 ≦ Mz / Z ≦ 0.8 (7)
In the case of Ez> Mz, 0.5 ≦ Mz / Z ≦ 0.7 (7)

The number of steps of the step edge 14d (14c) of the vibration substrate 10 is represented by i, the length in the X-axis direction of the _i- th step edge is Mx _i (i is a positive integer), and the outermost step edge The length in the X-axis direction is represented by Mx. When n is a positive integer, k is a positive number, the length of the excitation electrode in the X-axis direction is Ex, and the wavelength of bending vibration excited by the vibration substrate 10 is represented by λ, the equations (1) and (2 ) Can be expressed as the following equation.
(Mx _i-1 −Mx _i ) / 2 = nλ / 2 (8)
(Ex−Mx) = kλ / 2 (9)
In consideration of variations at the time of manufacture, the following expression is obtained as an allowable range with little influence on the characteristics of the vibration element 1.
−0.2 <((Mx _i−1 −Mx _i ) / 2−nλ / 2) / (λ / 2) <0.2 (10)
−0.2 <((Ex−Mx) −kλ / 2) / (λ / 2) <0.2 (11)

FIG. 7 is a schematic diagram illustrating a configuration of the vibration element 2 according to the second embodiment. 7A is a plan view of the vibration element 2, FIG. 7B is a QQ cross-sectional view of FIG. 7A, and FIG. 7C is a PP cross-sectional view of FIG. . The vibration element 2 shown in FIG. 7 is different from the vibration element 1 shown in FIG. 1 in the size of the excitation electrode 20a. The excitation electrode 20a extends to the outside of the step edges 14c, 14d, 14a, and 14b. Yes. When applied to general formulas (10) and (11), the number of steps i = 2, a positive integer n = 1, and an integer k = 2.
Similarly to the vibration element 1 shown in FIG. 1, the relationship between the Z′-axis direction dimension (short-side dimension) Z of the vibration substrate 10 and the short-side dimension Mz of the vibration unit 14 is expressed by Equation (7). It is desirable to be applied. By setting various parameters as described above, unnecessary vibration generated in the vibration element 2 is suppressed, and the vibration element 2 having a small CI can be obtained.

FIG. 8 is a schematic diagram illustrating a configuration of the vibration element 3 according to the third embodiment. 8A is a plan view of the resonator element 3, FIG. 8B is a cross-sectional view taken along the line QQ in FIG. 8A, and FIG. 8C is a cross-sectional view taken along the line P-P in FIG. . The vibration element 3 shown in FIG. 8 is different from the vibration element 1 shown in FIG. 1 in the size (width, protrusion length) of the second portion 16 of the vibration unit 14 and the size of the area of the excitation electrode 20a. The length of the XZ ′ surface of the second portion 16 in the X-axis direction is λ on one side, and the size of the excitation electrode 20a is larger than Ex (= Mx ₂ ) by λ / 2 on one side. When applied to the equations (10) and (11), the number of steps i = 2, a positive integer n = 2, and an integer k = 1.
Similarly to the vibration element 1 shown in FIG. 1, the relationship between the Z′-axis direction dimension (short-side dimension) Z of the vibration substrate 10 and the short-side dimension Mz of the vibration unit 14 is expressed by Equation (7). It is desirable to be applied. By setting various parameters as described above, unnecessary vibration generated in the vibration element 3 is suppressed, and the vibration element 3 having a small CI can be obtained.

FIG. 9 is a schematic diagram illustrating a configuration of the vibration element 4 according to the fourth embodiment. 9A is a plan view of the vibration element 4, FIG. 9B is a cross-sectional view taken along the line QQ in FIG. 9A, and FIG. 9C is a cross-sectional view taken along the line P-P in FIG. . The vibration element 4 shown in FIG. 9 is a vibration element having a mesa structure having three step edges in the X-axis direction and the Z′-axis direction, respectively. That is, the vibration unit 14 of the vibration element 4 includes a third portion 17 having a thickness smaller than that of the second portion 16 in addition to the first portion 15 and the second portion 16. The third portion 17 is formed at the central portion of the entire circumferential side surface of the second portion 16 so as to sandwich the first portion 15 and the second portion 16 from the X-axis direction and the Z′-axis direction. The steps of the step edge portions 14c and 14d extending in the X-axis direction are formed by the difference in thickness between the first portion 15, the second portion 16, and the third portion 17, as shown in FIG. 9B. In the illustrated example, the steps of the step edge portions 14c and 14d are formed such that the surface parallel to the Y′Z ′ plane of the first portion 15, the surface parallel to the XZ ′ plane of the second portion 16, and the second portion 16 A plane parallel to the Y′Z ′ plane, a plane parallel to the XZ ′ plane of the third portion 17, and a plane parallel to the Y′Z ′ plane of the third portion 17 are configured.
Further, the steps of the step edge portions 14a and 14b extending in the Z′-axis direction are formed by the difference in thickness of the first portion 15, the second portion 16, and the third portion 17, as shown in FIG. 9C. ing. In the example shown in FIG. 9C, the steps of the step edge portions 14a and 14b have a plane parallel to the XY ′ plane of the first portion 15, a plane parallel to the XZ ′ plane of the second portion 16, and the second The surface of the part 16 is parallel to the XY ′ plane, the surface of the third part 17 is parallel to the XZ ′ plane, and the surface of the third part 17 is parallel to the XY ′ plane.

The vibrating portion 14 including the first portion 15, the second portion 16, and the third portion 17 is projected in a bowl shape from the intermediate portion in the thickness direction of the entire circumferential side surface of the third portion 17, and the thickness of the third portion 17. A thinner outer edge 12 is formed. Excitation electrodes 20a and 20b formed on the vibrating portion 14 and a part of the outer edge portion 12 so as to face each other, the extraction electrodes 22a and 22b from the excitation electrodes 20a and 20b, and two terminations of the extraction electrodes 22a and 22b The electrode pads 24 a and 24 b are also formed in the same manner as the vibration element 1. The vibration element 4 can be manufactured by applying the method for manufacturing the vibration element 1. According to the vibration element 4, the energy confinement effect can be further enhanced as compared with the vibration elements 1, 2 and 3 having a two-stage mesa structure.
As is apparent from the step edge portions 14c and 14d, the three-stage mesa resonator shown in FIG. 6 has both the lengths (Mx _i-1 -Mx _i ) of adjacent step portions in the X-axis direction being λ / 2. is there. The size of the excitation electrode 20a is in the X-axis direction of the Mx ₁ longer by lambda / 2 on one side than the length. When applied to the equations (10) and (11), the number of steps i = 3, a positive integer n = 1, and an integer k = 3.
Similarly to the vibration element 1 shown in FIG. 1, the relationship between the Z′-axis direction dimension (short-side dimension) Z of the vibration substrate 10 and the short-side dimension Mz of the vibration unit 14 is expressed by Equation (7). It is desirable to be applied. By setting various parameters as described above, unnecessary vibration generated in the vibration element 4 is suppressed, and the vibration element 4 having a small CI can be obtained.

FIG. 10 is a schematic diagram illustrating a configuration of the vibration element 5 according to the fifth embodiment. FIG. 10A is a plan view of the vibration element 5, FIG. 10B is a cross-sectional view taken along the line QQ in FIG. 10A, and FIG. 10C is a cross-sectional view taken along the line P-P in FIG. . The vibration element 5 shown in FIG. 10 is different from the vibration element 4 shown in FIG. 9 in the size of the area of the excitation electrode 20a. The size of the excitation electrode 20 a is formed to be equal to the length in the X-axis direction of the edge of the third portion 17 of the vibrating portion 14. When applied to equations (10) and (11), the number of steps i = 3, n = 1, and k = 2.
Similarly to the vibration element 1 shown in FIG. 1, the relationship between the Z′-axis direction dimension (short-side dimension) Z of the vibration substrate 10 and the short-side dimension Mz of the vibration unit 14 is expressed by Equation (5). It is desirable to be applied. By setting various parameters as described above, unnecessary vibration generated in the vibration element 5 is suppressed, and the vibration element 5 having a small CI can be obtained.
In the above example, the description has been given of the vibration element 1 to the vibration element 5 having the two-stage type and the three-stage type mesa structure. However, the invention according to the present application is a multi-stage type mesa structure, and the number of stages of the mesa structure is particularly limited. Not.

The vibration element according to the present invention has a mesa structure including at least two step portions so that the entire outer peripheral edge of the vibration portion 14 of the vibration substrate 10 gradually decreases toward the outer edge portion 12. Since the length of the portion and the length of the excitation electrode are set based on the equations (10) and (11), the bending vibration is suppressed, and the excitation electrodes 20a and 20b cancel the electric charges of the bending vibration to be picked up. The frequency temperature characteristic and the CI temperature characteristic have an effect that smooth characteristics can be obtained. In addition, by forming the entire outer peripheral edge of the vibration part with at least a two-step structure, vibration energy is confined in the excitation part 14 and an effect is obtained that a vibration element with a small CI can be obtained.
In addition, since the bending vibration generated by the vibration substrate 10 is set appropriately for the length of each stage of the vibration portion 14 and the length of the excitation electrodes 20a and 20b, smooth frequency-temperature characteristics and CI characteristics can be obtained. There is an effect. Furthermore, by setting the sizes of the excitation electrodes 20a and 20b appropriately, there is an effect that the equivalent inductance of the vibration element can be matched with the customer's request.

It is possible to change the shape of the vibration displacement distribution by changing the number of steps of the vibration part 14 of the vibration substrate 10 and by changing the interval between adjacent steps, and an appropriate CI according to customer specifications. There is an effect that the inductance can be set. Further, by concentrating the vibration displacement distribution in the central portion, there is an effect that the influence of the support portion can be made difficult.
When the vibration substrate 10 is made of a quartz substrate, the frequency temperature characteristic and the CI temperature characteristic can be obtained smoothly, and the vibration element having small secular change and a large Q value of the vibration element can be obtained. .

  Next, a method for manufacturing the vibration element 1 shown in FIG. 1 will be described with reference to the drawings. FIG.11 and FIG.12 is a figure which shows typically the manufacturing process of the quartz substrate 10 of the vibration element 1 which concerns on this embodiment. As shown in FIG. 11A, the anticorrosion film 30 is formed on the front and back main surfaces (surfaces parallel to the XZ ′ plane) of the AT-cut quartz crystal substrate 10. The corrosion resistant film 30 is formed by, for example, laminating chromium (Cr) and gold (Au) in this order by sputtering or vacuum deposition, and then patterning the chromium and gold. The patterning is performed by, for example, a photolithography technique and an etching technique. The corrosion-resistant film 30 has corrosion resistance against a solution containing hydrofluoric acid that becomes an etching solution when the AT-cut quartz crystal substrate 10 is processed.

As shown in FIG. 11B, after applying a positive type photoresist film on the corrosion resistant film 30, the photoresist film is exposed and developed through a mask (not shown) arranged on both the front and back surfaces. Then, a resist film 40 having a predetermined shape is formed. The resist film 40 is formed so as to cover a part of the corrosion resistant film 30.
Next, as shown in FIG. 11C, a part of the resist film 40 is exposed again using a mask M to form a photosensitive portion 42. In the figure, the mask M is shown separated from the corrosion-resistant film 30 for easy understanding, but in actuality, the exposure is performed in close contact.
Next, as shown in FIG. 11D, the AT cut quartz crystal substrate 10 is etched using the corrosion resistant film 30 as a mask. Etching is performed using, for example, a mixed liquid of hydrofluoric acid (hydrofluoric acid) and ammonium fluoride as an etching liquid. Thereby, the external shape (shape when seen from the Y′-axis direction) of the quartz substrate 10 is formed.

Next, as shown in FIG. 12A, after etching the corrosion-resistant film 30 with a predetermined etching solution using the resist film 40 as a mask, the AT-cut quartz crystal substrate 10 is further formed using the above-mentioned mixed solution as an etching solution. When half-etching to a predetermined depth, the outer shape of the vibrating portion 14 is formed.
Next, as shown in FIG. 12B, the photosensitive portion 42 of the resist film 40 is developed and removed. Thereby, a part of the corrosion-resistant film 30 is exposed. Before developing the photosensitive portion 42, for example, an altered layer (not shown) formed on the surface of the resist film 40 is ashed by oxygen plasma generated by discharge in a vacuum or a reduced pressure atmosphere. Thereby, the photosensitive part 42 can be reliably developed and removed.

  Next, as shown in FIG. 12C, the resist film 40 is used as a mask and the exposed portion of the corrosion-resistant film 30 is removed by etching with a predetermined etching solution. The substrate 10 is half-etched to a predetermined depth. Thereby, a step (two steps in the example of FIG. 12) can be formed in each of the step edge portions 14c and 14d extending in the X′-axis direction. Further, although not shown, a step can be formed in each of the step edge portions 14a and 14b extending in the Z′-axis direction.

  Through the above steps, the quartz substrate 10 having the outer edge portion 12 and the vibrating portion 14 can be formed. After removing the resist film 40 and the corrosion-resistant film 30, chromium and gold are stacked in this order by, for example, sputtering or vacuum deposition, and then the chromium and gold are patterned, whereby the excitation electrode 20 a is applied to the quartz substrate 10. The extraction electrode 22a and the electrode pad 24a are formed. That is, as shown in the embodiment of FIG. 1, the excitation electrode 20 a is formed with the vibration element 1 provided in the entire region of the vibration portion 14 and a partial region of the outer edge portion 12 connected to the vibration portion 14. .

  Through the above steps, the resonator element 1 according to this embodiment can be manufactured. According to the method for manufacturing the vibration element 3, the resist film 40 used for forming the outer shape of the vibration portion 14 is developed to remove the photosensitive portion, and then the AT crystal substrate 10 is etched again using the resist film 40. Thus, the vibrating portion 14 can be formed. Therefore, the vibration part 14 having a two-stage mesa structure can be formed with high accuracy. For example, when a resist film is applied twice to form the vibrating portion 14 (for example, after forming the outer shape of the vibrating portion using the first resist film, the first resist film is peeled off and a new first resist film is formed). In the case where the two resist films are applied to expose the side surfaces of the vibration part, misalignment may occur between the first resist film and the second resist film, and the vibration part 14 may not be formed accurately. Such a problem can be solved by the manufacturing method of the vibration element 1.

Next, the vibrator according to the present embodiment will be described with reference to the drawings. FIG. 13 is a cross-sectional view schematically showing the vibrator 6 according to this embodiment. FIG. 13 is a cross-sectional view of the vibrator 6 in the longitudinal direction (X-axis direction), and is a cross-sectional view at the same position as the cross-sectional view of the resonator element 1 shown in FIG. The vibrator 6 is a vibration element 1 according to the present invention (in the illustrated example, the vibration element 1 is shown, but the vibration element may be the vibration element shown in FIG. 4, FIG. 5, FIG. 6, or FIG. 7), And a container 50.
The container 50 can accommodate the vibration element 1 in the cavity 52. Examples of the material of the container 50 include ceramic and glass. The cavity 52 is a space for the vibration element 1 to operate. The cavity 52 is hermetically sealed and has a reduced pressure space or an inert gas atmosphere.

  The vibration element 1 is accommodated in the cavity 52 of the container 50. A plurality of element mounting pads 55 a are provided at the end of the inner bottom surface of the cavity 52, and each element mounting pad 55 a is electrically connected to the plurality of mounting terminals 53 by an internal conductor 57. The vibration element 1 is mounted on the element mounting pad 55a, and the electrode pads 24a and 24b and the element mounting pads 55a are electrically connected and fixed via the conductive adhesive 60. In the illustrated example, the vibration element 1 is cantilevered in the cavity 52 by the conductive adhesive 60 applied to two points of the electrode pads 24a and 24b formed along the Z′-axis direction at the end. It is fixed to. As the conductive adhesive 60, for example, solder, silver paste, or the like can be used. A seal ring ring 50b is fired on the upper portion of the container body 50a. A lid member 50c is placed on the seal ring ring 50b and welded using a resistance welder to hermetically seal the cavity 52. The cavity 52 may be evacuated or filled with an inert gas.

  By configuring the vibrator as described above, bending vibration is suppressed and the CI value is reduced, that is, a small Q value having a large Q value, little secular change, smooth frequency temperature characteristics, and CI characteristics. There is an effect that a vibrator is obtained.

Next, the electronic device according to the present embodiment will be described with reference to the drawings.
FIG. 14A is a cross-sectional view of an example of an embodiment according to the electronic device 7 of the present invention. The electronic device 7 roughly includes the vibration element 1 of the present invention, a thermistor 58 that is a temperature-sensitive element, and a container 50 that houses the vibration element 1 and the thermistor 58. The container 50 includes a container body 50a and a lid member 50c. The container main body 50a is formed with a cavity 52 for accommodating the vibration element 1 on the upper surface side and a recess 54a for accommodating the thermistor 58 on the lower surface side. A plurality of element mounting pads 55 a are provided at the end of the inner bottom surface of the cavity 52, and each element mounting pad 55 a is electrically connected to the plurality of mounting terminals 53 by an internal conductor 57. The vibration element 3 is placed on the element mounting pad 55a, and each pad 24 and each element mounting pad 55a are electrically connected via the conductive adhesive 60 and fixed. A seal ring ring 50b is fired on the upper portion of the container body 50a. A lid member 50c is placed on the seal ring ring 50b and welded using a resistance welder to hermetically seal the cavity 52. The cavity 52 may be evacuated or filled with an inert gas.
On the other hand, a recess 54a is formed in the approximate center of the lower surface side of the container body 50a, and an electronic component mounting pad 55b is baked on the upper surface of the recess 54a. The thermistor 58 is mounted on the electronic component mounting pad 55b using solder or the like. The electronic component mounting pad 55 b is electrically connected to the plurality of mounting terminals 53 by the internal conductor 57.

FIG. 14B shows an electronic device 8 according to a modification of FIG. 14A, which is different from the electronic device 7 in that a concave portion 54b is formed on the bottom surface of the cavity 52 of the container body 50a. The thermistor 58 is connected to the electronic component mounting pad 55b fired on the bottom surface through a metal bump or the like. The electronic component mounting pad 55 b is electrically connected to the mounting terminal 53. That is, the vibration element 1 and the thermistor 58 of the temperature sensitive element are accommodated in the cavity 52 and hermetically sealed.
In the above, the example in which the vibration element 1 and the thermistor 58 are accommodated in the container 50 has been described. However, as an electronic component to be accommodated in the container 50, an electronic that accommodates at least one of a thermistor, a capacitor, a reactance element, and a semiconductor element. It is desirable to configure the device.

  As described above, the small vibration element 1 having a small CI according to the present invention is provided, and, for example, a temperature compensated vibration element, a vibration element with a wide variable range, a small oscillator, and the like are configured by combining with the electronic element to be used. Therefore, it is possible to provide various electronic devices according to customer specifications.

FIG. 15 is a cross-sectional view of an example of an embodiment according to the oscillator 9 of the present invention. The oscillator 9 includes the vibration element 1 of the present invention (an example of the vibration element 1 is shown in FIG. 15, but may be another vibration element of the present invention), a single-layer insulating substrate 70, and the vibration element 1. And an IC (semiconductor element) 88 for driving and a convex lid member 80 for hermetically sealing the surface space of the insulating substrate 70 including the vibration element 1 and the IC 88. The insulating substrate 70 has a plurality of element mounting pads 74a and electronic component mounting pads 74b for mounting the vibration element 1 and the IC 88 on the front surface, and a mounting terminal 76 for connection to an external circuit on the back surface. The element mounting pad 74 a and the electronic component mounting pad 74 b and the mounting terminal 76 are electrically connected by a conductor 78 that penetrates the insulating substrate 70. Furthermore, the element mounting pad 74a and the electronic component mounting pad 74b are electrically connected by a conductor wiring (not shown) formed on the surface of the insulating substrate 70. After the IC 88 is mounted on the electronic component mounting pad 74b using a metal bump or the like, the conductive adhesive 60 is applied to the element mounting pad 74a, and the electrode pads 24a and 24b of the vibration element 3 are placed on the IC mounting pad 74a. It is cured in the tank to make it conductive and fixed. The convex lid member 80 is hermetically sealed by melting the metallized 85 formed on the peripheral edge of the insulating substrate. At this time, the inside can be evacuated by performing the sealing step in a vacuum. As a sealing means, a means for melting and welding the lid member 80 using a laser beam or the like is also used. The internal space sealed with the lid member 80 may be a vacuum or may be filled with an inert gas.
In the above description, the embodiment in which the oscillator is configured using the vibration element has been described. However, the oscillator may be configured using the vibrator 6 and the semiconductor element (IC) 88 illustrated in FIG.
As described above, there is an effect that the oscillator can be downsized, and an oscillator having low power consumption and excellent frequency temperature characteristics can be realized.

16 and 17 are modifications of the embodiment of the vibration element 1 shown in FIG. 16 differs from the vibration element 1 in the size of the electrodes 20a and 20b in the X-axis direction, and the length of the electrodes 20a and 20b in the X-axis direction is the length of the first stepped portion. a point which is equal to the mx _1. 17 is different from the resonator element 1 in the size of the electrodes 20a and 20b in the Z′-axis direction, and the length of the electrodes 20a and 20b in the Z′-axis direction is the first step. This is a point set equal to the length Mz of the part. When the electrodes 20a and 20b are made larger in this way, the CI becomes smaller and the variable range becomes wider when used as an oscillator.
In the above description, the modification of FIG. 1 is described. However, in each of the resonator elements of FIGS. 7, 8, 9, and 10, the lengths of the electrodes 20a and 20b in the X-axis direction and the length in the Z′-axis direction are illustrated. 16 and 17 may be modified.

Next, the electronic apparatus according to the present embodiment will be described with reference to the drawings. FIG. 18 is a plan view schematically showing a mobile phone (smart phone) 100 as an electronic apparatus according to the present embodiment. The smartphone 100 includes the vibration element according to the present invention. More specifically, the smartphone 100 includes the electronic device according to the present invention. Below, as shown in FIG. 18, the example using the electronic device 9 provided with the vibration element 1 (1s, 2, 3, 4, 5) as an electronic device which concerns on this invention is demonstrated. For convenience, FIG. 18 shows the electronic device 9 in a simplified manner.
The smartphone 100 uses the electronic device 9 as a timing device such as a reference clock oscillation source, for example. The smartphone 100 can further include a display unit (liquid crystal display, organic EL display, etc.) 101, an operation unit 102, and a sound output unit 103 (microphone, etc.). The smartphone 100 may also use the display unit 101 as an operation unit by providing a contact detection mechanism for the display unit 101.

According to the smartphone 100, it is possible to have the vibration element 1 that can simplify the manufacturing process while suppressing bending vibration.
Note that, as described above, an electronic device typified by the smartphone (mobile phone) 100 includes an oscillation circuit that drives the vibration element 1 and a temperature compensation circuit that corrects a frequency variation caused by a temperature change of the vibration element 1. It is preferable to provide.
According to this, the electronic device represented by the smartphone 100 includes the oscillation circuit that drives the vibration element 1 and the temperature compensation circuit that corrects the frequency variation accompanying the temperature change of the vibration element 1. Therefore, it is possible to provide temperature compensation for the resonance frequency at which oscillation occurs and to provide an electronic device having excellent temperature characteristics.
In addition, the electronic device including the vibration element according to the present invention is not limited to the above smartphone, but an electronic book, a personal computer, a television, a digital still camera, a video camera, a video recorder, a navigation device, a pager, an electronic notebook, a calculator, and a word processor. It can be suitably used as a timing device for a workstation, a videophone, a POS terminal, a device equipped with a touch panel, or the like.

The above-described embodiments and modifications are merely examples, and the present invention is not limited to these. For example, it is possible to appropriately combine each embodiment and each modification.
The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1, 1s, 2, 3, 4, 5 ... Vibration element, 6 ... Vibrator, 7, 8 ... Electronic device, 9 ... Oscillator, 10 ... Vibration board, 12 ... Outer edge part, 13 ... Support part, 13a ... Support part Side surface, 14 ... vibrating portion, 14a, 14b, 14c, 14d ... step edge, 15 ... first portion, 16 ... second portion, 17 ... third portion, 20a, 20b ... excitation electrode, 22a, 22b ... extraction electrode 24a, 24b ... electrode pads, 26 ... support region, corrosion resistant film ... 30, resist film ... 40, 50 ... container, 50a ... container body, 50b ... seal ring, 50c ... lid member, 52 ... cavity, 53 ... mounting Terminals 54a ... Recesses 55a ... Element mounting pads 55b ... Electronic component mounting pads 57 ... Internal conductors 58 ... Thermistors 60 ... Electrical adhesives 70 ... Insulating substrates 74a ... Element mounting pads 74b ... Electronic component mounting De, 76 ... mounting terminal, 78 ... conductor, 80 ... cover member, 85 ... metallization, 88 ... IC, X ... X-axis direction length of the vibration substrate, Z ... vibration substrate Z 'in the axial length, Mx ₁ , Mx ₂ , Mx ₃ ... Length of the vibration part in the X-axis direction, Mz... Length of the vibration part in the Z′-axis direction, Ex... Length of the excitation electrode in the X-axis direction, Ez. Axial length, t ... thickness of vibrating part, t '... thickness of outer edge part

Claims (13)

A vibration part including a first convex part provided on one main surface and a second convex part provided on the other main surface on the back side with respect to the one main surface, excited by thickness shear vibration,
Step edges of at least two or more steps provided at ends of the first protrusion and the second protrusion in a direction intersecting the vibration direction of the thickness shear vibration ,
Thin outer edge thicknesses than the thickness of the disposed along the outer edge of the front Symbol vibration unit the vibrating portion,
And a support region in which an adhesive is disposed at a distance from the vibrating portion at the outer edge portion,
A substrate comprising:
A first excitation electrode provided on a surface of the first convex portion;
A second excitation electrode provided on the surface of the second convex part,
When the number of steps of the step edge is represented by a positive integer i of 2 or more,
i-th stage the stepped edge length along the front Kifu movement direction of the Mx _i,
Mx a length along the front Kifu movement direction of the step edge of the outermost in the direction of the thickness,
The length along the front Kifu movement direction before Symbol excitation electrodes Ex,
When the wavelength of bending vibration which vibrates in the vibration direction is lambda,
−0.2 <((Mx _i−1 −Mx _i ) / 2−nλ / 2) / (λ / 2) <0.2 (1)
−0.2 <((Ex−Mx) −kλ / 2) / (λ / 2) <0.2 (2)
(Where n is a positive integer and k is an integer)
A vibrating element characterized by satisfying And have you to claim 1,
The step number i of the stepped portion is 2,
The positive integer n is 1,
The integer k is -1,
A vibration element characterized in that Ex <Mx has a relationship between Ex and Mx. And have you to claim 1,
The step number i of the stepped portion is 2,
The positive integer n is 1,
The integer k is 2;
A vibration element characterized in that there is a relationship of Mx <Ex between the Ex and the Mx. And have you to claim 1,
The step number i of the stepped portion is 2,
The positive integer n is 2,
The integer k is 1;
A vibration element characterized in that there is a relationship of Mx <Ex between the Ex and the Mx. In claim 1,
The step number i of the stepped portion is 3,
The positive integer n is 1,
The integer k is 3,
And the Ex and the vibration element, characterized in that there is a relationship between Mx <Ex between the front Symbol M x. In claim 1,
The step number i of the stepped portion is 3,
The positive integer n is 1,
The integer k is 2;
And the Ex and the vibration element, characterized in that there is a relationship between Mx <Ex between the front Symbol M x. And have you to claim 1,
The substrate is a rotating Y-cut substrate;
The vibrating element has a side along the X-axis direction as a long side and a side along the Z′-axis direction as a short side. In any one of Claims 1 thru | or 7,
The length along the direction orthogonal to the vibration direction of the step edge of the first step is Mz,
When the length along the direction orthogonal to the vibration direction of the excitation electrode is Ez,
When Ez <Mz, the relationship 0.6 ≦ Mz / Z ≦ 0.8 is satisfied,
A vibration element characterized by satisfying a relationship of 0.5 ≦ Mz / Z ≦ 0.7 when Ez> Mz.   A vibrator comprising: the vibration element according to claim 1; and a container that houses the vibration element.   An electronic device comprising: the vibration element according to claim 1; an electronic element; and a container that houses the vibration element and the electronic element. In claim 10,
An electronic device, wherein the electronic element is at least one of a thermistor, a capacitor, a reactance element, and a semiconductor element.   An oscillator comprising: the vibrator according to claim 9; and an oscillation circuit that drives the vibrator.   An electronic device comprising the vibration element according to claim 1.

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