JP6137274B2 - Vibration element, vibrator, electronic device, and electronic apparatus - Google Patents

Description

  The present invention relates to a piezoelectric vibrator that excites a thickness shear vibration mode, and more particularly, to a piezoelectric vibration element, a piezoelectric vibrator, an electronic device, and an electronic device using the piezoelectric vibrator having a so-called inverted mesa structure.

AT-cut quartz resonators have thickness shear vibration as the main vibration mode to be excited, and are suitable for miniaturization and higher frequency, and exhibit a cubic curve with excellent frequency temperature characteristics. Used in many ways.
Patent Document 1 discloses an AT-cut crystal resonator having a so-called inverted mesa structure in which a concave portion is formed on a part of a main surface to increase the frequency. A so-called Z ′ long substrate is used in which the length in the Z′-axis direction of the quartz substrate is longer than the length in the X-axis direction.
Patent Document 2 discloses an AT-cut quartz resonator having an inverted mesa structure in which a thick support portion is connected to three sides of a rectangular thin vibration portion, and one side of the thin vibration portion is exposed. Is disclosed. Further, the quartz crystal resonator piece is an in-plane rotated AT-cut quartz substrate formed by rotating the X-axis and the Z′-axis of the AT-cut quartz substrate in the range of −120 ° to + 60 ° around the Y′-axis, It is said to be a structure that secures a vibration region and is excellent in mass productivity (multiple picking).

In Patent Documents 3 and 4, an AT-cut crystal having an inverted mesa structure in which a thick support portion is connected to three sides of a rectangular thin vibration portion, and one side of the thin vibration portion is exposed. A resonator is disclosed, and a so-called X long substrate in which the length in the X-axis direction of the quartz crystal substrate is longer than the length in the Z′-axis direction is used as the quartz crystal resonator element.
In Patent Document 5, a thick support portion is connected to two adjacent sides of a rectangular thin vibration portion, and a thick portion is provided in an L shape in plan view. An AT-cut crystal resonator having an inverted mesa structure having a structure in which two sides are exposed is disclosed. A Z ′ long substrate is used as the quartz substrate.
However, in Patent Document 5, in order to obtain an L-shaped thick portion, as described in FIGS. 1 (c) and 1 (d) of Patent Document 5, along the line segment α and the line segment β. The thick part is deleted, but the deletion is based on the premise that it will be deleted by machining such as dicing, so the chipping or cracking damage will occur on the cut surface, and the ultra thin part will be damaged. There is. In addition, problems such as generation of unnecessary vibration that causes spurious noise and an increase in CI value occur in the vibration region.
Patent Document 6 discloses an AT-cut crystal resonator having an inverted mesa structure having a structure in which a thick support portion is connected to only one side of a thin vibration portion and three sides of the thin vibration portion are exposed. Yes.

Patent Document 7 discloses an AT-cut vibrator having an inverted mesa structure in which a concave portion is formed so as to be opposed to each other on both main surfaces and front and back surfaces of a quartz substrate. An X long substrate is used as the quartz substrate, and a structure is proposed in which excitation electrodes are provided in a region where the flatness of the vibration region formed in the recessed portion is ensured.
By the way, it is known that the thickness-shear vibration mode excited in the vibration region of the AT-cut crystal resonator has an elliptical shape in which the vibration displacement distribution has a major axis in the X-axis direction due to the anisotropy of the elastic constant. Patent Document 8 discloses a piezoelectric vibrator that excites thickness-shear vibration having a pair of ring-shaped electrodes arranged symmetrically on the front and back surfaces of a piezoelectric substrate. The difference between the outer peripheral diameter and the inner peripheral diameter of the ring electrode is set so that the ring electrode excites only the symmetrical zero-order mode and hardly excites the other nonharmonic higher-order modes.

Patent Document 9 discloses a piezoelectric vibrator in which the shape of a piezoelectric substrate and excitation electrodes provided on the front and back surfaces of the piezoelectric substrate are both elliptical.
Patent Document 10 discloses that both ends of the quartz substrate in the longitudinal direction (X-axis direction) and both ends of the electrode in the X-axis direction are semi-elliptical, and the ratio of the major axis to the minor axis of the ellipse (long) A crystal resonator having an axis / short axis) of approximately 1.26 is disclosed.
Patent Document 11 discloses a crystal resonator in which an elliptical excitation electrode is formed on an elliptical crystal substrate. The ratio of the major axis to the minor axis is preferably 1.26: 1, but considering the variation in manufacturing dimensions, the range of 1.14 to 1.39: 1 is practical.

Patent Document 12 discloses a piezoelectric vibrator having a structure in which a notch or a slit is provided between a vibrating part and a support part in order to further improve the energy confinement effect of the thickness-slip piezoelectric vibrator.
By the way, when the piezoelectric vibrator is miniaturized, there is a case where the electrical characteristics are deteriorated or the frequency aging characteristics are deteriorated due to the residual stress caused by the adhesive. Patent Literature 13 discloses a crystal resonator in which a notch or a slit is provided between a vibrating portion and a support portion of a rectangular flat plate AT-cut crystal resonator. By using such a structure, it is possible to suppress the residual stress from spreading to the vibration region.
Patent Document 14 discloses a vibrator in which a notch or a slit is provided between a vibrating portion and a support portion of an inverted mesa piezoelectric vibrator in order to improve (relax) mount strain (stress). . Patent Document 15 discloses a piezoelectric vibrator in which conduction between electrodes on the front and back surfaces is ensured by providing a slit (through hole) in a support portion of an inverted mesa piezoelectric vibrator.

Patent Document 16 discloses a crystal resonator that suppresses an unnecessary mode of a higher-order contour system by providing a slit in a support portion of an AT-cut crystal resonator in a thickness shear vibration mode.
Further, in Patent Document 17, a spurious structure is provided by providing a slit in a connecting portion of a thin vibrating portion of an inverted mesa AT-cut crystal resonator and a thick holding portion, that is, a residue portion having an inclined surface. A vibrator that suppresses the above is disclosed.

JP 2004-165743 A JP 2009-164824 A JP 2006-203700 A JP 2002-198772 A JP 2002-033640 A JP 2001-144578 A JP 2003-264446 A JP-A-2-079508 JP 9-246903 A JP 2007-158486 A JP 2007-214941 A Japanese Utility Model Publication No. 61-187116 Japanese Patent Laid-Open No. 9-326667 JP 2009-158999 A JP 2004-260695 A JP 2009-188483 A JP 2003-087087 A

In recent years, there has been a strong demand for miniaturization, high frequency, and high performance of piezoelectric devices. However, in order to reduce the size and increase the frequency, the piezoelectric vibrator having the structure as described above has the CI value of the main vibration and the CI value ratio of adjacent spurious (= CIs / CIm, where CIm is the CI value of the main vibration. CIs is a CI value of spurious, and one example of the standard is 1.8 or more), etc. In particular, when the frequency is as high as several hundred MHz, the film thickness of the excitation electrode and the lead electrode formed on the piezoelectric vibration element becomes a problem. When only the main vibration of the piezoelectric vibration element is set to the confinement mode, there is a problem that the electrode film becomes thin, ohmic cross occurs, and the CI value of the piezoelectric vibration element increases.
In addition, when the film thickness is increased in order to prevent ohmic crossing of the electrode film, there is a problem in that many in-harmonic modes other than the main vibration become a confinement mode and the adjacent spurious CI value ratio cannot be satisfied.
Therefore, the present invention has been made to solve the above-described problem, and has achieved high frequency (100 to 500 MHz band), reduced the CI value of the main vibration, and satisfied electrical requirements such as a spurious CI value ratio. It is an object of the present invention to provide a piezoelectric vibration element, a piezoelectric vibrator, an electronic device, and an electronic apparatus using the piezoelectric vibrator of the present invention.

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.
A vibration element according to an aspect of the present invention has a surface along the X-axis direction and the Z-axis direction in the XYZ orthogonal coordinate system and a thickness along the Y-axis direction, the first region including the vibration region, and the first A substrate including a second region having a thickness greater than one region; a first excitation electrode provided on one main surface side of the substrate in the first region; and the other main surface side of the substrate A second excitation electrode provided in the first region, wherein the first region includes a first outer edge and a second outer edge along the Z-axis direction, and along the X-axis direction. And the second region includes a first thick portion main body provided along the first outer edge, and the first outer edge and the first thickness. The thickness increases between the first outer edge and the first thick part main body provided between the first main body and the first main body. A first thick part having an inclined part, a second thick part main body provided along the third outer edge, and the third outer edge and the second thick part main body. A second thick portion having a second inclined portion that is provided between the third outer edge and increases in thickness toward the second thick portion main body. The first thick portion is provided on the one main surface side and connected to the first excitation electrode, and the first thick portion is provided on the other main surface side, and the first thick portion in the plan view. A second pad electrode overlapping with the second excitation electrode and connected to the second excitation electrode, wherein the first excitation electrode has a fifth outer edge and a sixth outer edge along the X-axis direction. The first pad electrode passes through the fifth outer edge and passes through the first imaginary line along the X-axis direction and the sixth outer edge in a plan view. A between the second imaginary line along the axial direction, characterized in that it is arranged on the first virtual line closer.
In the resonator element according to another aspect of the invention, one main surface of the first thick portion protrudes from one main surface of the first region, and the other of the first thick portions. The main surface of the first region and the other main surface of the first region are the same surface, and one main surface of the second thick portion protrudes from one main surface of the first region, The other main surface of the thick part 2 and the other main surface of the first region are the same surface.
In the resonator element according to another embodiment of the present invention, the substrate is a crystal axis of crystal, the electric axis is the X axis, the mechanical axis is the Y axis, the optical axis is the Z axis, and the X axis is The Z axis is tilted so that the + Z side rotates in the −Y direction of the Y axis, and the Y axis is tilted so that the + Y side rotates in the + Z direction of the Z axis. The quartz substrate is characterized in that the axis is the Y′-axis, the surface including the X-axis and the Z′-axis is the main surface, and the thickness along the direction along the Y′-axis.
In the resonator element according to another aspect of the invention, the one main surface of the first thick portion and the one main surface of the second thick portion are the one of the first regions. Projecting in the + Y direction of the Y ′ axis from the main surface of the Y ′ axis .
In the vibration element according to another aspect of the present invention, the second thick portion is in the + Z ′ direction of the Z ′ axis.
In the vibration element according to another aspect of the present invention, the first thick portion is in the + X direction of the X axis.
A vibrator according to an aspect of the invention includes the vibration element according to the aspect of the invention and a package in which the vibration element is housed.
An electronic device according to an aspect of the present invention includes the vibration element according to the above aspect of the present invention and an electronic component.
An electronic device according to another aspect of the invention is characterized in that the electronic component is any one of a variable capacitance element, a thermistor, an inductor, and a capacitor.
An electronic device according to another embodiment of the present invention is characterized in that a package includes an oscillation circuit that excites the vibration element.
An electronic apparatus according to another aspect of the invention includes the vibrator.

  Application Example 1 A piezoelectric vibration element according to the present invention includes a piezoelectric substrate having a vibration part including a vibration region, and a support unit that is integrated with the vibration part and is thicker than the vibration region. A piezoelectric vibration element having a pair of excitation electrodes disposed so as to face each other on the front and back sides, wherein the support section includes a first support section disposed along one side of the vibration section, and A second support portion provided along one side and the other side adjacent to the one side, and each of the first support portion and the second support portion is provided with one end connected thereto, One main surface of one support portion protrudes from one main surface of the vibration portion, and the other main surface of the first support portion and the other main surface of the vibration portion are the same surface. The one main surface of the second support portion protrudes from the one main surface of the vibrating portion, and the other main surface of the second support portion. The other main surface of the vibration part is the same surface, and the thickness of the first support part increases as the distance from the one edge connected to one side of the vibration area increases toward the other edge. A first inclined portion, and a first support body that is connected to the other end edge of the first inclined portion, and the first support portion has at least one slit. The piezoelectric vibration element is provided.

  According to this configuration, the high-frequency piezoelectric vibration element using the fundamental wave is miniaturized and mass-produced. Furthermore, by providing a slit between the support portion and the vibration region, it is possible to suppress the spread of stress caused by adhesion and fixation, and thus a piezoelectric vibration element having excellent frequency temperature characteristics, CI temperature characteristics, and frequency aging characteristics can be obtained. There is an effect that it is. In addition, since the excitation electrode, the lead electrode, and the pad electrode are made of metal materials having different configurations and are formed with an appropriate film thickness, the CI value of the main vibration is small, and the CI value of the main vibration is small. There is an effect that a piezoelectric vibration element having a large ratio of CI values of adjacent spurious, that is, a large CI value ratio can be obtained.

  Application Example 2 The piezoelectric substrate includes the X axis of an orthogonal coordinate system including an X axis as an electric axis that is a crystal axis of crystal, a Y axis as a mechanical axis, and a Z axis as an optical axis. An axis obtained by tilting the Z-axis by a predetermined angle in the −Y direction of the Y-axis as a center is defined as a Z′-axis, and an axis tilted by the predetermined angle in the + Z-direction of the Z-axis by a predetermined angle as Y ′. The piezoelectric vibration element according to Application Example 1, wherein the piezoelectric vibration element is a quartz substrate that includes a plane parallel to the X-axis and the Z′-axis and has a thickness parallel to the Y′-axis. is there.

  By using the piezoelectric substrate cut at the cutting angle as described above to configure the piezoelectric vibration element, it is possible to configure the piezoelectric vibration element of the required specification with a more suitable cut angle and There is an effect that it is possible to obtain a high-frequency piezoelectric vibration element having a frequency frequency characteristic with a small CI value and a large CI value ratio.

  [Application Example 3] In the piezoelectric vibration element according to Application Example 2, the first and second support portions protrude on the plus side of the Y ′ axis.

  By configuring the first and second support parts in this way, there is an advantage that the piezoelectric vibration element can be fixed to the container while avoiding distortion applied to the vibration part.

  Application Example 4 The piezoelectric vibration element according to Application Example 2 or 3, wherein the projecting portion of the second support portion is on the plus side of the Z ′ axis.

  By configuring the second support portion in this manner, there is an advantage that the piezoelectric vibration element can be fixed to the container while avoiding a two-step inclination due to etching generated on the plus side of the Z ′ axis.

  Application Example 5 In the piezoelectric vibration element according to any one of Application Examples 2 to 4, wherein the projecting portion of the first support portion is on the plus side of the X axis.

  By configuring the projecting portion of the first support portion in this manner, there is an advantage that the piezoelectric vibration element can be fixed to the container while avoiding a two-step inclination caused by etching that occurs on the positive side of the X axis. .

  Application Example 6 The application example 1 is characterized in that the slit is disposed in the first support body along the boundary between the first inclined portion and the first support body. The piezoelectric vibration element according to claim 1.

  According to this configuration, the piezoelectric vibration element is miniaturized, and a slit is provided between the vibration region and the supported portion, so that the spread of stress generated when the piezoelectric vibration element is bonded and fixed can be suppressed. Therefore, there is an effect that a piezoelectric vibration element having excellent frequency temperature characteristics, CI temperature characteristics, and frequency aging characteristics can be obtained.

  Application Example 7 The piezoelectric vibration according to any one of Application Examples 1 to 5, wherein the slit is disposed in the first inclined portion so as to be separated from one side of the vibration region. It is an element.

  According to this configuration, the piezoelectric vibration element is reduced in size, and the slit is provided in the inclined portion between the vibration region and the supported portion, so that the slit can be easily formed, and the piezoelectric vibration element is bonded and fixed. Since it is possible to suppress the spread of the stress that occurs during the process, it is possible to obtain a piezoelectric vibration element having excellent frequency temperature characteristics and CI temperature characteristics.

  Application Example 8 The slit includes a first slit disposed in the first support body, and a second slit disposed away from one side of the vibration region in the first inclined portion. The piezoelectric vibration element according to any one of Application Examples 1 to 5, wherein the piezoelectric vibration element is provided.

  According to this configuration, the piezoelectric vibration element is miniaturized and two slits are provided between the vibration region and the supported portion, so that the stress spread generated when the piezoelectric vibration element is bonded and fixed can be reduced. The piezoelectric vibration element can be obtained with excellent suppression of frequency reproducibility, frequency temperature characteristics, CI temperature characteristics, and frequency aging characteristics.

  Application Example 9 In the application example, the first slit is disposed in the first support portion main body along a boundary portion between the first inclined portion and the first support portion main body. The piezoelectric vibration element according to Application Example 8.

  As described above, since the first slit is provided along the boundary between the first inclined portion and the first support portion main body, the spread of stress generated when the piezoelectric vibration element is bonded and fixed is further suppressed. There is an effect that can be.

  Application Example 10 A piezoelectric vibrator including the piezoelectric vibration element according to any one of Application Examples 1 to 9 and a package that accommodates the piezoelectric vibration element.

  According to this configuration, the high-frequency fundamental piezoelectric vibrator is downsized, and the portion supporting the piezoelectric vibration element is a single point, so that stress caused by adhesion and fixation can be reduced, and frequency reproducibility, There is an effect that a piezoelectric vibrator excellent in frequency temperature characteristics, CI temperature characteristics, and frequency aging characteristics can be obtained. Furthermore, since the excitation electrode, the lead electrode, and the pad electrode are made of metal materials having different configurations and are formed with an appropriate film thickness, the CI value of the main vibration is small and the CI value of the main vibration is small. There is an effect that a piezoelectric vibrator having a large ratio of CI values of adjacent spurious, that is, a large CI value ratio, and a piezoelectric vibrator having a small capacitance ratio can be obtained.

  Application Example 11 An electronic device comprising a package including the piezoelectric vibration element according to any one of Application Examples 1 to 9 and an electronic component.

  When an electronic device in which a piezoelectric vibration element and an electronic component (thermistor) are housed in a package is configured as described above, the temperature change of the piezoelectric vibration element is changed because the thermistor of the temperature sensitive element is disposed very close to the piezoelectric vibration element. There is an effect that can be detected quickly. Further, by incorporating the electronic component, there is an effect that the burden on the device side to be used can be reduced.

  Application Example 12 In the electronic device according to Application Example 11, the electronic component is any one of a variable capacitance element, a thermistor, an inductor, and a capacitor.

  In this way, when an electronic device (piezoelectric device) is configured by using any one of a variable capacitance element, thermistor, inductor, and capacitor as an electronic component, a device that is more suitable for the electronic device with the required specifications can be reduced in size and cost. There is an effect that it can be realized.

  [Application Example 13] The electronic device according to Application Example 11 or 12, wherein the package includes an oscillation circuit for exciting the piezoelectric vibration element.

According to this configuration, there is an effect that a voltage-controlled piezoelectric oscillator having excellent frequency reproducibility, frequency temperature characteristics, and aging characteristics and having a small size and a high frequency (for example, 490 MHz band) can be obtained. In addition, since the piezoelectric device uses a piezoelectric vibration element having a fundamental wave, the capacitance ratio is small and the frequency variable width is widened. Furthermore, there is an effect that a voltage controlled piezoelectric oscillator having a good S / N ratio can be obtained.
In addition, a piezoelectric oscillator, a temperature compensated piezoelectric oscillator, or the like can be configured as the piezoelectric device, and there is an effect that a piezoelectric oscillator excellent in frequency reproducibility, aging characteristics, and frequency temperature characteristics can be configured.

  Application Example 14 An electronic apparatus comprising the piezoelectric vibrator according to Application Example 10.

  According to this configuration, since the piezoelectric vibrator of the present invention is used for an electronic device, there is an effect that an electronic device including a reference frequency source having a high frequency and excellent frequency stability and a good S / N ratio can be configured.

It is the schematic which showed the structure of the piezoelectric vibration element 1 which concerns on this invention, (a) is a top view, (b) is sectional drawing which looked at the PP cross section from + X-axis direction, (c) is It is sectional drawing which looked at PP section from the -X-axis direction, (d) is sectional drawing which looked at QQ section from + Z'-axis direction. The figure explaining the relationship between an AT cut quartz substrate and a crystal axis. (A) is a top view which shows the structure of a lead electrode and a pad electrode, (b) is a top view which shows the structure of an excitation electrode. FIG. 6 is a plan view showing a configuration of a modification of the piezoelectric vibration element 1. FIG. 6 is a plan view showing a configuration of another modification of the piezoelectric vibration element 1. It is the schematic which showed the structure of the piezoelectric vibration element 2 of 2nd Embodiment, (a) is a top view, (b) is sectional drawing which looked at the PP cross section from + X-axis direction, (c ) Is a cross-sectional view of the PP cross section viewed from the −X axis direction, and (d) is a cross section of the QQ cross section viewed from the + Z ′ axis direction. It is the schematic which showed the structure of the piezoelectric vibration element 3 of 3rd Embodiment, (a) is a top view, (b) is sectional drawing which looked at the PP cross section from + X-axis direction, (c ) Is a cross-sectional view of the PP cross section viewed from the −X axis direction, and (d) is a cross section of the QQ cross section viewed from the + Z ′ axis direction. FIG. 4A is a plan view illustrating a configuration of a modification of the piezoelectric vibration element 3, and FIG. 5B is a plan view illustrating a configuration of a modification of the piezoelectric vibration element 1. FIG. 6 is a plan view showing a configuration of a modification of the piezoelectric vibration element 1. The manufacturing process figure of the piezoelectric substrate of this invention. The manufacturing process figure of the excitation electrode and lead electrode of the piezoelectric vibration element of this invention. (A) is a top view of each recessed part formed in the piezoelectric wafer, (b)-(e) is sectional drawing of the X-axis direction of a recessed part. (A) is a top view of each recessed part formed in the piezoelectric wafer, (b)-(e) is sectional drawing of the Z'-axis direction of a recessed part. (A) is a perspective view of the piezoelectric vibrator 1 shown in FIG. 1, and (b) is a QQ longitudinal sectional view (a view showing only a cut surface). (A) is a longitudinal cross-sectional view of the piezoelectric vibrator 5 according to the present invention, and (b) is a plan view. FIG. 3 is a longitudinal sectional view of an electronic device (piezoelectric device) 6. (A) is a longitudinal cross-sectional view of the electronic device (piezoelectric device) 7, (b) is a top view. The longitudinal cross-sectional view of the modification of the electronic device (piezoelectric device) 7. FIG. FIG. (A), (b), (c) is structure explanatory drawing of the piezoelectric substrate which concerns on a modification. (A), (b), (c) is structure explanatory drawing of the piezoelectric substrate which concerns on another modification. It is a modification of the piezoelectric vibration element 1 which concerns on this invention, (a) is a top view, (b) is an enlarged view of the principal part, (c) is sectional drawing of the principal part.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a configuration of a piezoelectric vibration element 1 according to an embodiment of the present invention. 1A is a plan view of the piezoelectric vibration element 1, FIG. 1B is a cross-sectional view of the PP cross section viewed from the + X axis direction, and FIG. 1C is a cross section of the PP cross section viewed from the −X axis direction. It is sectional drawing, (d) is sectional drawing which looked at the QQ cross section from + Z 'axial direction.
The piezoelectric vibration element 1 includes a rectangular vibration portion 12 including a thin vibration region, a piezoelectric substrate 10 having a thicker thickness than the vibration region 12 and integrated with the vibration region 12, and the surface of the vibration region 12. Excitation electrodes 25a and 25b respectively disposed on the back surface, and lead electrodes 27a and 27b provided extending from the respective excitation electrodes 25a and 25b toward the pad electrodes 29a and 29b provided on the support portion 13, respectively. It is equipped with. Here, the vibration region refers to a region where vibration energy is confined, that is, a region where the vibration energy is almost zero, and the ratio between the size of the vibration region in the X-axis direction and the size of the vibration region in the Z′-axis direction. As is well known, it is 1.26: 1. Further, the vibration part refers to the entire piezoelectric substrate including the vibration area and its peripheral part.

The piezoelectric substrate 10 has a rectangular and thin plate-like vibration region 12, a first support portion 14 disposed along one side 12 a of the four sides of the vibration region 12, and one side of the vibration region 12. And a second support portion 15 disposed along another side 12b adjacent to 12a. That is, the piezoelectric substrate 10 includes L-shaped thick support portions (support portions) 13 (14, 15) integrated along two adjacent sides 12a, 12b of the vibration region 12.
The first support portion 14 is connected to one side 12 a of the thin flat plate-like vibration region 12, and is connected from one end (inner end edge) to the other end (outer end edge) connected to one side 12 a of the vibration region 12. The first inclined portion 14b whose thickness gradually increases as the distance from the first inclined portion 14b increases, and the thick square columnar first support portion that is connected to the other end (outer end edge) of the first inclined portion 14b. And a main body 14a. Similarly, the second support portion 15 is connected to one side 12b of the thin flat plate-like vibration region 12, and from one edge (inner edge) connected to the one side 12b of the vibration region 12 to the other edge. A second inclined portion 15b having a thickness that gradually increases as it is separated toward the (outer end edge), and a thick quadrangular prism-shaped first connecting to the other end (outer end edge) of the second inclined portion 15b. 2 support part main bodies 15a.

One main surface (back surface) of the vibration region 12 and one main surface (back surface) of each of the first and second support portions 14 and 15 are on the same plane, that is, the X-axis of the coordinate axis shown in FIG. It is on a plane parallel to the Z ′ plane, and one main surface (the back surface side of FIG. 1B) is called a flat surface (flat surface), and the other main surface is the opposite surface (FIG. 1 ( The surface side b) is referred to as a concave surface.
The first and second support portions 14 and 15 are provided so as to protrude only on the other main surface side (surface side) of the piezoelectric substrate.
One main surface of the first support portion 14 is formed so as to protrude from one main surface (surface) of the vibration portion 12. The other main surface of the first support portion 14 and the other main surface of the vibrating portion are continuously connected to each other and are configured to be the same surface. Even when there is a protruding energy confinement region on the mesa in the vibration region, the main surface of the peripheral portion of the vibration region is continuously connected to the other main surface of the first support portion 14, What is necessary is just to be comprised so that it may become the same surface.
One main surface of the second support portion 15 is formed so as to protrude from one main surface (surface) of the vibration portion 12. The other main surface of the second support portion 15 and one main surface of the vibrating portion are continuously connected to each other and are configured to be the same surface. Even when there is a protruding energy confinement region on the mesa in the vibration region, the main surface of the peripheral portion of the vibration region is continuously connected to the other main surface of the second support portion 15; What is necessary is just to be comprised so that it may become the same surface.
The first support portion 14 includes at least one stress relaxation slit 20 that accompanies mounting of the piezoelectric vibration element 1 between the vibration region 12 and the pad electrodes 29a and 29b that are supported portions. It is formed so as to penetrate along the direction. In the embodiment shown in FIG. 1, the slit 20 is formed in the plane of the first support body 14a along the boundary (joint section) between the second inclined portion 14b and the first support body 14a. Has been.
The support body (14a, 15a) refers to a region having a constant thickness in the Y′-axis direction.

  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. In the quartz substrate, a flat plate cut out from the quartz along a plane obtained by rotating the XZ plane around the X axis by a predetermined angle θ is used for the piezoelectric vibration element. For example, in the case of the AT-cut quartz substrate 10, θ is approximately 35 ° 15 ′. Note that the Y-axis and the Z-axis are also rotated by θ around the X-axis to be the Y′-axis and the Z′-axis, respectively. Accordingly, the AT cut quartz crystal substrate 10 has orthogonal crystal axes X, Y ′, and Z ′. The AT-cut quartz substrate 10 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 thickness shear vibration is the main vibration. Excited.

That is, as shown in FIG. 2, the piezoelectric substrate 10 is centered on the X axis of an orthogonal coordinate system composed of an X axis (electrical axis), a Y axis (mechanical axis), and a 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. This is an AT-cut quartz substrate having a thickness in a parallel direction.
As shown in FIG. 1A, the piezoelectric substrate 10 has a direction parallel to the X axis (hereinafter referred to as “X axis”) with a direction parallel to the Y ′ axis (hereinafter referred to as “Y ′ axis direction”) as a thickness direction. It has a rectangular shape having a long side as a “direction” and a short side as a direction parallel to the Z ′ axis (hereinafter referred to as “Z ′ direction”).
The piezoelectric substrate 10 is not limited to a rectangular shape, and may be a square or other quadrangular shape. In addition, the piezoelectric substrate according to the present invention is not limited to the AT cut with the angle θ of approximately 35 ° 15 ′, but can be applied to a wide variety of piezoelectric substrates such as a BT cut that excites thickness shear vibration. Yes.

  In the embodiment shown in FIG. 1, the excitation electrodes 25 a and 25 b that drive the piezoelectric substrate 10 have a quadrangular shape, and are formed to face both the front and back surfaces (upper surface and lower surface both surfaces) of the substantially central portion of the vibration region 12. Yes. The size of the area of the excitation electrode 25b on the back surface (flat surface) side is set to be sufficiently larger than the size of the excitation electrode 25a on the front surface side (concave surface side). This is because the energy confinement coefficient due to the mass effect of the excitation electrode is not increased more than necessary. That is, by sufficiently increasing the excitation electrode 25b on the back surface side (flat surface side), the plate back amount Δ (= (fs−fe) / fs, where fs is the cutoff frequency of the piezoelectric substrate and fe is the piezoelectric substrate. The frequency when the excitation electrode is attached to the entire surface depends only on the mass effect of the excitation electrode 25a on the surface side (upper surface side).

The excitation electrodes 25a and 25b are formed by depositing, for example, nickel (Ni) on a base and superposing gold (Au) thereon using a vapor deposition apparatus or a sputtering apparatus. The thickness of the gold (Au) is such that only the main vibration (S0) is confined in a range in which the ohmic cross does not increase, and the oblique symmetric inharmonic mode (A0, A1...) And the symmetric inharmonic mode (S1) , S3...) Are preferably not in the confinement mode. However, for example, if an attempt is made to configure a piezoelectric vibration element of an extremely high frequency band such as the 490 MHz band, if the film is formed so as to avoid ohmic crossing of the electrode film thickness, the lower-order inharmonic mode should not be confined. I can't.
The lead electrode 27a extended from the excitation electrode 25a formed on the front surface side passes through the second inclined portion 15b and the second support portion main body 15a from the vibration region 12, and the first support portion main body 14a. Is electrically connected to a pad electrode 29a formed on the upper surface of the substrate. Further, the lead electrode 27b extending from the excitation electrode 25b formed on the back surface side passes through the edge of the back surface of the piezoelectric substrate 10 and the pad electrode 29b formed on the back surface of the first support body 14a. And continuity connection.

The embodiment shown in FIG. 1A is an example of a lead-out structure of the lead electrodes 27a and 27b, and the lead electrode 27a may pass through another support portion. However, it is desirable that the length of the lead electrodes 27a and 27b is the shortest, and it is desirable to suppress the increase in capacitance by considering that the lead electrodes 27a and 27b do not intersect with each other with the piezoelectric substrate 10 interposed therebetween.
Further, in the embodiment example of FIG. 1, an example in which the pad electrodes 29 a and 29 b are formed facing the front and back surfaces of the piezoelectric substrate 10, respectively. When the piezoelectric vibration element 1 is accommodated in the package, as described later, the piezoelectric vibration element 1 is turned over, and the pad electrode 29a and the element mounting pad of the package are mechanically fixed and electrically connected with a conductive adhesive. The pad electrode 29b and the electrode terminal of the package are electrically connected using a bonding wire. Thus, when the site | part which supports the piezoelectric vibration element 1 becomes one point, it is possible to make small the stress resulting from a conductive adhesive.

The reason why the slit 20 is provided between the vibration region 12 and the pad electrodes 29a and 29b that are the support portions of the piezoelectric vibration element 1 is to prevent the spread of stress generated when the conductive adhesive is cured.
That is, when the piezoelectric vibration element is bonded and fixed to the package with a conductive adhesive, first, the conductive adhesive is applied to the supported portion (pad electrode) 29a of the first supporting portion main body 14a, and this is applied to the package. Place it on the element mounting pad and apply weight. In order to cure the conductive adhesive, it is held at a high temperature for a predetermined time. In the high temperature state, both the first support part main body 14a and the package expand and the adhesive temporarily softens, so that no stress is generated in the first support part main body 14a. When the conductive adhesive is cured and the first support portion main body 14a and the package are cooled and the temperature returns to room temperature (25 ° C.), the conductive adhesive, the package, and the first support portion main body 14a. The difference in coefficient of linear expansion results in the stress that arises from the cured electroconductive adhesive. This stress spreads from the first support part main body 14a to the second support part 15, from the first inclined part 14b, and from the second inclined part 15b to the vibration region 12. In order to prevent the spread of the stress, a slit 20 for stress relaxation is provided.
Thus, since the slit 20 is arranged close to the boundary portion (connection portion) of the first support body 14a, a large area of the supported portion (pad electrode) 29a of the first support portion body 14a is ensured. The diameter of the conductive adhesive to be applied can be increased. On the other hand, when the slit 20 is disposed near the supported portion (pad electrode) 29a of the first support body 14a, the area of the supported portion (pad electrode) 29a is reduced, and the diameter of the conductive adhesive is reduced. Must be reduced. As a result, the absolute amount of the conductive filler contained in the conductive adhesive is also reduced, the conductivity is deteriorated, the resonance frequency of the piezoelectric vibration element 1 is not stabilized, and the frequency fluctuation (commonly referred to as F jump) is likely to occur. There is.
Therefore, it is preferable that the slit 20 is arranged close to the boundary portion (joint portion) of the first support body 14a.

In order to obtain the stress (strain) distribution generated in the piezoelectric substrate 10, a simulation is generally performed using a finite element method. The smaller the stress in the vibration region 12, the better the piezoelectric vibration element having frequency temperature characteristics, frequency reproducibility, frequency aging characteristics, and the like.
Silicone-based, epoxy-based, polyimide-based, bismaleimide-based, etc. are generally used as the conductive adhesive, but taking into account the frequency aging of the piezoelectric vibration element 1 due to degassing, polyimide-based conductivity An adhesive was used. Since the polyimide-based conductive adhesive is hard, it is possible to reduce the magnitude of the generated stress by supporting one point rather than supporting two separate points (two-point support). For this reason, a single-point support (single-point support) structure is used for the piezoelectric vibration element 1 for a voltage-controlled piezoelectric oscillator (VCXO) having a high frequency band of 100 to 500 MHz, for example, 490 MHz. That is, as will be described later, the pad electrode 29a is mechanically fixed to the element mounting pad of the package using conductive adhesion and is also electrically connected. The other pad electrode 29b is connected to the electrode terminal of the package and the bonding wire. It was decided to make an electrical connection using.

  Further, the outer shape of the piezoelectric substrate 10 shown in FIG. 1 is a so-called X-long in which the length in the X-axis direction is longer than the length in the Z′-axis direction. This is because stress is generated when the piezoelectric substrate 10 is bonded and fixed with a conductive adhesive or the like. As is well known, the frequency change when pressure is applied to both ends of the AT-cut quartz substrate in the X-axis direction. And frequency change when the same pressure is applied to both ends in the Z′-axis direction are compared, the frequency change is smaller when pressure is applied to both ends in the Z′-axis direction. That is, it is preferable to provide the support points along the Z′-axis direction because the frequency change due to stress is reduced.

  3A is a plan view showing the arrangement and configuration of the lead electrodes 27a and 27b and the pad electrodes 29a and 29b formed on the piezoelectric substrate 10, and FIG. 3B is a plan view of the excitation electrodes 25a and 25b. It is a top view which shows arrangement | positioning and a structure. The lead electrode 27a extends from the edge of the excitation electrode 25a assumed on the surface, passes through the surface of the second support portion 15, and is provided on the surface of the center portion of the first support portion 14 as a pad electrode 29a. It is formed so as to be continuously provided. The lead electrode 27b extends from the edge of the excitation electrode 25b assumed on the back surface, and is a pad electrode provided on the back surface of the central portion of the first support portion 14 along the periphery of the back surface (flat surface). It is formed so as to be connected to 29b. Each of the lead electrodes 27a and 27b includes a first layer made of a chromium (Cr) thin film and a second layer made of a gold (Au) thin film laminated on the first layer. An enlarged view of the RR cross section of a part 27aA of the lead electrode 27a is shown in a broken line circle 27A on the left side. A lead electrode 27a is formed by laminating a thin gold film 27g on the chromium thin film 27c on the surface side (upper surface side) of the second support body 15a. The same applies to the lead electrode 27b.

The pad electrodes 29a and 29b provided on the front and back surfaces of the central portion of the first support portion 14 are each composed of a first layer made of a thin film of chromium (Cr) and gold laminated on the first layer ( And a second layer made of a thin film of Au). An enlarged view of the TT cross section of a part 29A of the pad electrode 29a is shown in a lower broken line circle 29A. A pad electrode 29a is formed by laminating a thin gold film 29g on the chromium thin film 29c on the surface side (upper surface side) of the first support body 14a. The same applies to the pad electrode 29b.
Since the lead electrodes 27a and 27b and the pad electrodes 29a and 29b are formed in the same process, an example of the film thickness is that the first layer of chromium (Cr) thin film is 100 mm (1 mm = 0.1 nm (nanometer)). ), A gold (Au) thin film is formed as thick as 2000 mm. For this reason, the ohmic cross of the lead electrodes 27a and 27b and the pad electrodes 29a and 29b does not occur, and the bonding strength is sufficient.
Note that another metal film may be sandwiched between a chromium (Cr) thin film and a gold (Au) thin film.

FIG. 3B is a plan view showing the arrangement and configuration of the excitation electrodes 25a and 25b formed on the piezoelectric substrate 10 so as to be aligned with the lead electrodes 27a and 27b formed in the previous step. The excitation electrode 25a is formed on the front surface side where the concave portion 11 is present, and the excitation electrode 25b which is sufficiently larger than the area of the excitation electrode 25a and fits within the area is formed on the back surface side (flat surface side).
Here, in forming the excitation electrodes 25a and 25b, the excitation electrodes 25a and 25b are formed so as to at least partially overlap the lead electrodes 27a and 27b previously formed in the previous step. For example, as shown in FIG. 3B, the excitation electrode 25a has a portion 27d of the lead electrode extending from the end. A portion 27d of the lead electrode is configured to overlap the surface of the lead electrode 27a. By configuring in this way, the excitation electrode 25a and the lead electrode 27a can be electrically and reliably connected, and it is possible to prevent conduction failure. The excitation electrode 25b formed on the back side (flat surface side) has the same configuration.
Or you may form so that a part of lead electrode 27b previously formed in a previous process may enter into the field of excitation electrode 25b (overlap). At this time, since the plate back amount that determines the resonance frequency depends only on the mass effect of the excitation electrode 25a formed on the main surface on the concave side that is the surface side, the plate back amount does not change from the design value. As described above, a part of the lead electrode 27b is configured to be located outside the outer shape of the excitation electrode 25a so as not to overlap with the excitation electrode 25a sandwiching the piezoelectric substrate 10 therebetween.
An example of the configuration of the excitation electrodes 25a and 25b includes a first layer made of a nickel (Ni) thin film and a second layer made of a gold (Au) thin film laminated on the first layer. . A part of the excitation electrodes 25a and 25b and a U-U cross-sectional view of a broken line circle are shown in a broken line circle on the right side. A thin film 25n of nickel (Ni) is formed on the first layer on the front and back surfaces of the vibration region 12, and a thin film 25g of gold (Au) is formed on the second layer. As an example of the film thickness, the nickel (Ni) thin film of the first layer is 70 mm, and the gold (Au) thin film is 600 mm.
Note that another metal film may be sandwiched between a nickel (Ni) thin film and a gold (Au) thin film.

  When the fundamental frequency of the vibration region 12 of the piezoelectric substrate 10 is set to a very high frequency band of 490 MHz, the electrode materials of the lead electrodes 27a and 27b, the pad electrodes 29a and 29b, and the excitation electrodes 25a and 25b, respectively. The reason why the electrode film thickness is made different will be described below. The lead electrodes 27a and 27b, the pad electrodes 29a and 29b, and the excitation electrodes 25a and 25b are composed of, for example, a 70-thick nickel (Ni) thin film in the first layer and a 600-thick gold (Au) thin film in the second layer. . Although the main vibration is sufficiently confined and its crystal impedance (CI; equivalent resistance) is also small, the film thickness of the gold (Au) of the lead electrodes 27a and 27b is so thin that there is a risk that an ohmic cross of the thin film may occur. . Furthermore, if the pad electrodes 29a and 29b are formed of a 70 mm nickel (Ni) thin film and a 600 mm gold (Au) thin film, the wire bonding strength may be insufficient.

  The lead electrodes 27a and 27b, the pad electrodes 29a and 29b, and the excitation electrodes 25a and 25b are composed of, for example, a 70-thin chromium (Cr) thin film in the first layer and a 600-thin gold (Au) thin film in the second layer. Then, since the thin film of gold (Au) is thin, chromium (Cr) is diffused into the thin film of gold (Au) by heat, so that ohmic cross of the thin film is generated and the CI of the main vibration may be increased.

Therefore, in the present invention, the formation process of the lead electrodes 27a and 27b, the pad electrodes 29a and 29b, and the excitation electrodes 25a and 25b is separated, and the material and the film thickness of each electrode thin film are changed. I decided to set it to be optimal for the function. That is, the excitation electrodes 25a and 25b have the main vibration as a confinement mode and the adjacent in-harmonic mode as a propagation mode (non-confinement mode) as much as possible. Thinly set. On the other hand, the lead electrodes 27a and 27b and the pad electrodes 29a and 29b are made of a chromium (Cr) film having a thickness of 100 mm and a gold (Au) film in order to reduce the film resistance of the thin lead electrode and increase the bonding strength of bonding. The thickness was set to 2000 mm.
The above film thickness is an example and is not limited to this value. In consideration of energy confinement theory and thin film ohmic cross, a multilayer film of nickel (Ni) and gold (Au) having an optimum film thickness was used for the excitation electrodes 25a and 25b. The lead electrodes 27a and 27b and the pad electrodes 29a and 29b are formed in a laminated film of chromium (Cr) and gold (Au) having a necessary thickness in consideration of the thin film ohmic cross and the bonding strength. Was used.
A method for manufacturing the excitation electrodes 25a and 25b, the lead electrodes 27a and 27b, and the pad electrodes 29a and 29b will be described later.

In the embodiment shown in FIG. 1, an example in which the excitation electrodes 25a and 25b are quadrangular, that is, square or rectangular (the long side is the X-axis direction) is shown, but it is not necessary to be limited to this. In the embodiment shown in FIG. 4, the excitation electrode 25a on the front surface side is circular, and the excitation electrode 25b on the back surface side is a quadrangle sufficiently larger than the area of the excitation electrode 25a. The excitation electrode 25b on the back side may be a circle with a sufficiently large area.
In the embodiment shown in FIG. 5, the excitation electrode 25a on the front surface side is elliptical, and the excitation electrode 25b on the back surface side is a quadrangle sufficiently larger than the area of the excitation electrode 25a. In the case of quartz, the displacement distribution in the X-axis direction differs from the displacement in the Z′-axis direction due to the anisotropy of the elastic constant, and the cut surface obtained by cutting the displacement distribution by a plane parallel to the XZ ′ plane is elliptical. become. Therefore, the piezoelectric vibration element 1 can be driven most efficiently when the elliptical excitation electrode 25a is used. That is, the capacitance ratio γ (= C0 / C1, where C0 is the capacitance and C1 is the series resonance capacitance) of the piezoelectric vibration element 1 can be minimized. The excitation electrode 25a may be oval.

FIG. 6 is a schematic diagram illustrating a configuration of the piezoelectric vibration element 2 according to the second embodiment. 6A is a plan view of the piezoelectric vibration element 2, FIG. 6B is a cross-sectional view of the PP cross section viewed from the + X axis direction, and FIG. 6C is a cross section of the PP cross section viewed from the −X axis direction. It is sectional drawing, (d) is sectional drawing which looked at the QQ cross section from + Z 'axial direction.
The piezoelectric vibrating element 2 is different from the piezoelectric vibrating element 1 shown in FIG. 1 in the position where a stress relaxation slit 20 is provided. In this example, the slit 20 is formed in the first inclined portion 14 b that is separated from the edge of the one side 12 a of the thin vibration region 12. Rather than forming the slit 20 in the first inclined portion 14b so that one edge of the slit 20 is in contact with the one side 12a along one side 12a of the vibration region 12, both ends of the first inclined portion 14b are formed. A slit 20 is provided apart from the edge. That is, in the first inclined portion 14b, an extremely thin inclined portion 14bb connected to the edge of the one side 12a of the vibration region 12 is left. In other words, an extremely thin inclined portion 14bb is formed between the side 12a and the slit 20.

  The reason for leaving the ultra-thin inclined portion 14bb is as follows. That is, when a high frequency voltage is applied to the excitation electrodes 25a and 25b arranged in the vibration region 12 to excite the vibration region 12, the inharmonic mode (A0, S1, A1, S2,...) In addition to the main vibration (S0). Is excited. Desirably, only the main vibration (S0) mode is set as a confinement mode, and the other inharmonic modes are set as propagation modes (unconfined modes). However, when the vibration region 12 becomes thin and the fundamental frequency becomes several hundred MHz, the excitation electrode needs to have a predetermined thickness or more in order to avoid ohmic cross of the electrode film. For this reason, when the thickness of the excitation electrode is equal to or greater than the predetermined thickness, the low-order inharmonic mode close to the main vibration becomes the confinement mode. The inventor of the present application has come to realize that in order to suppress the magnitude (CI) of the amplitude of the low-order inharmonic mode, it is only necessary to prevent the condition that the standing wave of the inharmonic mode is satisfied. . That is, the shape of both end edges in the Z′-axis direction of the vibration region 12 in FIG. 6 is asymmetric, and the shape of both end edges in the X-axis direction is also asymmetric with the strips 14bb remaining. It was found that the amplitude of the standing wave was suppressed.

FIG. 7 is a schematic diagram illustrating a configuration of the piezoelectric vibration element 3 according to the third embodiment. 7A is a plan view of the piezoelectric vibration element 3, FIG. 7B is a cross-sectional view of the PP cross section viewed from the + X axis direction, and FIG. 7C is a cross section of the PP cross section viewed from the −X axis direction. It is sectional drawing, (d) is sectional drawing which looked at the QQ cross section from + Z 'axial direction.
The piezoelectric vibration element 3 is different from the piezoelectric vibration element 1 shown in FIG. 1 in that a first slit 20a is provided in the surface of the first support body 14a and a first slit 20b is formed in the surface of the first inclined portion 14b. The second slit 20b is formed, and two slits for stress relaxation are provided. The purpose of forming individual slits in the plane of the first support section main body 14a and in the plane of the second inclined section 14b has already been described, and is omitted here.

FIG. 8A is a plan view showing a configuration of a modification of the piezoelectric vibration element 3 shown in FIG. The 1st slit 20a is provided in the surface of the 1st support part main body 14a, and the 2nd slit 20b is provided in the surface of the 1st inclination part 14b. However, the first slit 20a and the second slit 20b are not stepped in the X-axis direction as shown in the plan view of FIG. 7A, but are stepped so as to be separated from each other in the Z′-axis direction. The piezoelectric vibration element 3 is different from the piezoelectric vibration element 3 in that the piezoelectric vibration element 3 is arranged to be shifted. By providing the two slits 20a and 20b, the effect of suppressing the stress caused by the conductive adhesive so as not to spread to the vibration region 12 can be enhanced.
FIG. 8B is a modification of the piezoelectric vibration elements 1 and 2 of the first and second embodiments shown in FIGS. 1 and 6, and the slit 20 includes the first support body 14a and the first inclined portion. 14b and 14b. By forming the slit 20 in this way, it is possible to expect the effect of simultaneously satisfying the effects of the structures of FIGS. 1 and 6, and the effect of suppressing the stress caused by the conductive adhesive so as not to extend to the vibration region 12. Can be increased.

FIG. 9 is a plan view showing a configuration of a modification of the piezoelectric vibration element 1 of the embodiment shown in FIG. The lead electrode 27a extends from the edge of the excitation electrode 25a on the front surface, passes through the surface of the second support portion 15, and continues to the pad electrode 29a provided on the center surface of the first support portion 14. It is formed to be installed. The lead electrode 27b extends from the edge of the excitation electrode 25b on the back surface, and is connected to the pad electrode 29b provided on the back surface of the center portion of the first support portion 14 via the end portion of the back surface. It is formed as follows. A difference from the piezoelectric vibration element 1 of the embodiment shown in FIG. 1 is a position where the pad electrodes 29a and 29b are arranged. The pad electrodes 29a and 29b are provided apart from each other on the surface of the first support body 14a. The pad electrode 29b is formed with a conductor thin film across the edge of the piezoelectric substrate 10 so as to be electrically connected to the lead electrode 27b formed on the back surface. The pad electrodes 29a and 29b are configured so that conduction is easily achieved when a conductive adhesive is applied to the pad electrodes 29a and 29b on the surface side, and is inverted and placed on the element mounting pad of the package. Has been.
That is, in the embodiment of FIG. 9, a conductive adhesive is applied to two places (two points) of the first support portion 14 on one surface of the piezoelectric vibration element 1 so as to achieve conduction, support and fixation. This is the structure. Although the structure is suitable for reducing the height, the stress caused by the conductive adhesive may be slightly increased. Therefore, it can be expected that the influence of the stress on the vibration region can be suppressed by employing a piezoelectric vibration element provided with two slits as shown in FIGS. 7 and 8 as the third embodiment. Alternatively, when the hardness of the conductive adhesive is relatively hard, by reducing the center-to-center distance between the “two places (two points)” where the conductive adhesive is applied, the distortion caused by the mounting between the two points. There is also a technique for reducing (stress). On the other hand, by using a silicone-based adhesive whose conductive adhesive is relatively soft, the conductive adhesive is buffered and the distortion (stress) associated with the mounting between the two points is reduced. There is also a technique.

FIG. 10 is a manufacturing process diagram relating to the formation of the recessed portion 11, the outer shape, and the slit of the piezoelectric substrate 10. Here, a quartz wafer is taken as an example of the piezoelectric wafer, and the drawing shows only a cross section. In step S1, a quartz wafer 10W having a predetermined thickness, eg, 80 μm, whose both surfaces are polished is sufficiently washed and dried, and then chromium (Cr) is ground on the front and back surfaces by sputtering or the like. A metal film (corrosion resistant film) M in which gold (Au) is laminated is formed.
In step S2, a photoresist film (referred to as a resist film) R is applied to both surfaces of the metal film M on the front and back surfaces. In step S3, the resist film R in a portion corresponding to the recessed portions on the front and back surfaces is exposed using an exposure apparatus and a mask pattern. When the exposed resist film R is developed and the exposed resist film is peeled off, the metal films M at positions corresponding to the recessed portions on the front and back surfaces are exposed. When the gold layer films M exposed from the respective resist films R are dissolved and removed using a solution such as aqua regia, the crystal planes at positions corresponding to the recessed portions on the front and back surfaces are exposed.

In step S4, the exposed quartz surface is etched from the surface using a mixed solution of hydrofluoric acid (hydrofluoric acid) and ammonium fluoride until a desired thickness is obtained. In step S5, the resist films R on both sides are peeled off using a predetermined solution, and the exposed metal films M on both sides are removed using aqua regia or the like. At this stage, the quartz wafer 10W is in a state in which the recessed portions 11 formed on one side are regularly arranged in a lattice shape. In step S6, a metal film M (Cr + Au) is formed on both surfaces of the quartz wafer 10W obtained in step S5. In step S7, a resist film R is applied to both surfaces of the metal film M (Cr + Au) formed in step S6.
In step S8, each resist film R in a portion corresponding to the outer shape of the piezoelectric substrate 10 and a slit (not shown) is exposed from both the front and back surfaces using an exposure apparatus and a predetermined mask pattern, and developed to develop each resist. The film R is peeled off. Further, the exposed metal film M is removed by dissolving with a solution such as aqua regia.

In step S9, the exposed quartz surface is etched using a mixed liquid of hydrofluoric acid (hydrofluoric acid) and ammonium fluoride to form the outer shape of the piezoelectric substrate 10 and a slit. In step S10, the remaining resist film R is peeled off, and the exposed excess metal film M is dissolved and removed. At this stage, the quartz wafer 10W is in a state in which the piezoelectric substrates 10 are connected by supporting strips and are regularly arranged in a lattice shape.
In addition, although the external shape of the cross section orthogonal to the X axis is shown, the external shape of the cross section orthogonal to the Z ′ axis is also processed by double-sided etching so that the shape shown in FIG. 1 is obtained.
After step S10 is completed, the thickness of the vibration region 12 of each piezoelectric substrate 10 regularly arranged in a lattice pattern on the quartz wafer 10W is measured using, for example, an optical technique. When the measured thickness of each vibration region 12 is thicker than a predetermined thickness, the thickness is finely adjusted so as to fall within the predetermined thickness range.

  Next, after the thickness of the vibration region 12 of each piezoelectric substrate 10 formed on the quartz wafer 10 </ b> W is adjusted within a predetermined thickness range, excitation electrodes 25 a and 25 b and lead electrodes are applied to each piezoelectric substrate 10. The procedure for forming 27a and 27b will be described with reference to the manufacturing process diagram shown in FIG. In step S11, a chromium (Cr) thin film is formed on the entire front and back surfaces of the quartz wafer 10W by sputtering or the like, and a gold (Au) thin film is stacked thereon to form a metal film M. Next, in step S12, a resist is applied to each of the metal films M to form a resist film R. In step 13, the resist film R in a portion corresponding to the lead electrode and the pad electrode is exposed using the mask pattern Mk for the lead electrode and the pad electrode. In the next step S14, the resist film R is developed, and the unnecessary resist film R is peeled off. The metal film M exposed by the peeling is dissolved and removed with a solution such as aqua regia. The resist film on the lead electrode and the pad electrode is left as it is.

  In the next step S15, a nickel (Ni) thin film is formed on the entire front and back surfaces of the quartz wafer 10W by sputtering or the like, and a gold (Au) thin film is laminated thereon to form a metal film M. Further, a resist film R is applied on the metal film M. In the figure of step S15, the metal film for the lead electrode and the pad electrode and the resist film (M + R) are represented by the symbol C in order to avoid complexity. Then, the resist film R in a portion corresponding to the excitation electrode is exposed using the mask pattern Mk for the excitation electrode. In step S16, the exposed resist film R is developed to remove the unnecessary resist film R using a solution. In the next step S17, the metal film M exposed by peeling off the resist film R is dissolved and removed with a solution such as aqua regia. In step S18, the symbol C (metal film and resist film for lead electrode and pad electrode) is expressed by returning to (M + R), and when the unnecessary resist film R remaining on the metal film M is peeled off, each piezoelectric substrate 10 is exposed. (Ni + Au) excitation electrodes 25a and 25b, (Cr + Au) lead electrodes 27a and 27b, and pad electrodes 29a and 29b are formed (step S19). By dividing the half-etched support strip connected to the quartz wafer 10W, a divided piezoelectric vibration element can be obtained.

By the way, when the crystal is wet-etched, the etching proceeds along the Z-axis, but has an etching anisotropy peculiar to the crystal in which the etching rate varies depending on the direction of each crystal axis. Therefore, the etching surface that appears due to the anisotropy of the etching appears to differ depending on the direction of each crystal axis. Has been discussed. However, despite this background, there is no clearly organized data on the etching anisotropy of quartz, and the nanofabrication technical aspects are so strong that the etching conditions (types of etching solutions) Depending on the literature, there are many cases where there are differences in the crystal planes appearing, depending on the difference in the etching rate and etching temperature.
Therefore, the inventor of the present invention repeats etching simulation and trial production, and surface analysis and observation at the nano level in manufacturing the piezoelectric substrate according to the present invention using the photolithography technique and the wet etching technique, and the present invention relates to the present invention. The piezoelectric vibrator has been found to be in the following mode, and will be described in detail below.

FIGS. 12 and 13 are diagrams for explaining the cross-sectional shape of the recessed portion 11 on the AT-cut quartz crystal wafer 10W formed by the photolithography technique and the etching technique.
FIG. 12A is a plan view of the quartz wafer 10W in step S5 of FIG. At this stage, the concave portions 11 are regularly formed in a lattice shape on one surface of the quartz wafer 10W. FIG. 12B is a cross-sectional view in the X-axis direction, and each wall surface of the recessed portion 11 is not a vertical wall surface but an inclined surface. That is, the wall surface in the −X axis direction forms the inclined surface X1, and the wall surface in the + X axis direction forms the inclined surface X2. When a groove perpendicular to the X axis is formed, the wall surface X3 of the cross section of the groove has a wedge shape. FIGS. 10C to 10E are enlarged views of the wall surfaces X1 and X2 of the recessed portion 11 and the wall surface X3 of the groove portion. The wall surface in the −X-axis direction is etched with an inclination of approximately 62 degrees with respect to the plane of the crystal wafer 10W, as shown in FIG. As shown in FIG. 10D, the wall surface in the + X axis direction is orthogonal (90 degrees) to the plane of the quartz wafer 10W and etching proceeds slightly, but thereafter, etching proceeds with a gentle inclination. The bottom surface of the formed recess 11 is etched parallel to the original plane of the quartz wafer. That is, the vibration region 12 has a flat plate shape whose front and back surfaces are parallel.
FIG. 12E is a cross-sectional view of the groove portion for breaking formed in the quartz wafer 10W. The cross section of the groove formed perpendicular to the X axis has a wedge shape. This is because the wall surface X3 of the groove portion is formed by the wall surface X1 in the −X axis direction and the wall surface X2 in the + X axis direction, so that it becomes a wedge shape.
When providing an electrode on the surface on which the recessed portion 11 is formed, it is necessary to pay attention to the vertical wall surface of the wall surface X2 formed in the + X axis direction. It is desirable to avoid the electrode film because it tends to tear.

FIG. 13 is a view for explaining the wall surface of the recessed portion 11 formed in the piezoelectric substrate 10, particularly a sectional view in the Z′-axis direction. FIG. 13A is a plan view of the quartz wafer 10W. FIG. 13B is a cross-sectional view of the quartz wafer 10W in the Z′-axis direction. The wall surface in the −Z′-axis direction forms an inclined surface Z1, and the wall surface in the + Z′-axis direction forms an inclined surface Z2. When the groove portion orthogonal to the Z ′ axis is formed, the wall surface Z3 of the cross section of the groove portion has a wedge shape.
FIGS. 11C to 11E are enlarged views of the wall surfaces Z1 and Z2 of the recessed portion 11 and the wall surface Z3 of the groove portion. The wall surface in the −Z′-axis direction is etched with a relatively gentle inclination with respect to the plane of the quartz wafer 10 </ b> W, as shown in FIG. As shown in FIG. 11D, the wall surface Z2 in the + Z′-axis direction is etched with a steeply inclined surface Z2a with respect to the plane of the crystal wafer 10W, but thereafter, etching proceeds with a gently inclined surface Z2b. After that, the inclined surface Z2c becomes gentler. FIG. 13E is a cross-sectional view of a groove portion formed perpendicular to the Z′-axis direction, which is a wedge-shaped cross section Z3. This groove is a groove for folding the quartz crystal wafer 10W. Since the wall surface Z3 of the groove is formed of the wall surface Z1 in the -Z 'axis direction and the wall surface Z2 in the + Z' axis direction, the wall surface Z2a and the wall surface Z2b have a substantially wedge-shaped cross section. If the groove for folding is formed in the X-axis direction and the Z′-axis direction, the cross-sectional shape becomes a wedge shape, and the folding is easy.

One of the features of the present invention is that, as shown in FIG. 13 (d), a gentle inclined surface Z2c that is not parallel to the original plane on the right side of the dotted line indicated by Zc in the vibration region 11 and connected to this. This is to reduce the size of the piezoelectric substrate by etching away the thick portion 17 to be provided, the inclined surface X2 shown in FIG. 12 (d), and the thick portion 16 provided continuously therewith. That is, the vibration region 12 is the piezoelectric substrate 10 in which two adjacent sides are held by the L-shaped support portion 13.
Furthermore, a manufacturing method was established on the premise that both the gently inclined surface Z2 and the thick portion 17 and the inclined surface X2 and the thick portion 16 were deleted. For this reason, the area of the flat ultrathin portion that becomes the vibration region is ensured to be larger than that of the conventional structure having thick portions existing at both ends of the vibration region along the X axis as described in the prior art. Realized that. As a result, in the thickness-shear vibration mode excited in the vibration region, it is possible to design considering the fact that the vibration displacement distribution becomes an ellipse having a major axis in the X-axis direction due to the anisotropy of the elastic constant. Therefore, the ratio of the major axis to the minor axis is preferably 1.26: 1. However, considering the variation in manufacturing dimensions, etc., it is sufficiently designed to be in the range of 1.14 to 1.39: 1. It has become possible.

14 is a more detailed view of the piezoelectric vibration element 1 shown in FIG. 1, FIG. 14 (a) is a perspective view, and FIG. 14 (b) is a cut view of a QQ section in FIG. 1 (a). It is. As shown in FIGS. 14A and 14B, the outer shape of the piezoelectric vibration element 1 has an inclined surface on the end surface intersecting the X axis. That is, the inclined surface 1 in FIG. 14A appears on the end surface on the −X axis side, and the inclined surface 2 in FIG. 14B appears on the end surface on the + X axis side. The cross-sectional shapes parallel to the XY ′ plane of the inclined surface 1 and the inclined surface 2 are different.
In addition, in the vicinity where both the inclined surfaces 1 and 2 intersect with the main surface of the piezoelectric substrate, a vertical wall surface of the wall surface X2 formed in the + X axis direction as shown in FIGS. 12B and 12D appears. Absent. The reason for this is that, compared to the etching time required to form the recess 11, the time for forming the inclined surface 1 and the inclined surface 2 starts etching the piezoelectric substrate (quartz substrate) from the front and back, and the front and back penetrates. Since the etching time is sufficiently long, the vertical wall surface does not appear due to the overetching action.
The inclined surfaces a1 and a2 constituting the inclined surface 1 are substantially symmetrical with respect to the X axis, and in the inclined surfaces b1, b2, b3 and b4 constituting the inclined surface 2, b1 and b4, b2 and b3 are , Each of which is found to be substantially symmetrical with respect to the X axis. Further, the inclination angle α with respect to the X axis of the inclined surfaces a1 and a2 and the inclination angle β with respect to the X axis of the inclined surfaces b1 and b4 are in a relationship of β <α.

As shown in FIG. 1, FIG. 6, and FIG. 7, the high-frequency piezoelectric vibration element using the fundamental wave is miniaturized and mass-produced, and a slit is provided between the support portion and the vibration region. Since the spread of stress due to adhesion / fixation can be suppressed, there is an effect that a piezoelectric vibration element having excellent frequency temperature characteristics, CI temperature characteristics, and frequency aging characteristics can be obtained. Further, as shown in the embodiment of FIG. 3, the excitation electrodes 25a and 25, the lead electrodes 27a and 27b, and the pad electrodes 29a and 29b are made of metal materials having different configurations, and have appropriate film thicknesses. As a result, there is an effect that a piezoelectric vibration element having a small CI value of the main vibration and a ratio of the CI value of the adjacent spurious to the CI value of the main vibration, that is, a large CI value ratio can be obtained.
1 and 3, the excitation electrodes 25a and 25b are formed of a laminated film of nickel and gold, and the lead electrodes 27a and 27b and the pad electrodes 29a and 29b are laminated of chrome and gold. Since it is formed of a film, the CI value of the main vibration is small, and the ratio of the CI value of the adjacent spurious to the CI value of the main vibration, that is, the CI value ratio is large. effective.

Since the piezoelectric substrate 10 is formed as shown in the cutting angle diagram of FIG. 2, it is possible to configure the piezoelectric vibration element of the required specification with a more suitable cut angle, and the frequency temperature according to the specification. There is an effect that a high-frequency piezoelectric vibration element having characteristics, a small CI value, and a large CI value ratio can be obtained.
In addition, by using a quartz AT-cut quartz substrate as the piezoelectric substrate 10, the experience and experience regarding photolithography and etching techniques can be utilized, so that not only mass production of piezoelectric substrates is possible, but also a highly accurate piezoelectric substrate is obtained. Accordingly, there is an effect that the piezoelectric vibration element having a small CI value and a large CI value ratio can be mass-produced.

FIGS. 15A and 15B are diagrams showing a configuration of the piezoelectric vibrator 5 according to the embodiment of the present invention. FIG. 15A is a longitudinal sectional view, and FIG. 15B is a plan view in which a lid member is omitted. . The piezoelectric vibrator 5 includes, for example, a piezoelectric vibration element 1 and a package that accommodates the piezoelectric vibration element 1. The package includes a package main body 40 formed in a rectangular box shape and a lid member 49 made of metal, ceramic, glass, or the like.
As shown in FIG. 15, the package body 40 is formed by laminating a first substrate 41, a second substrate 42, and a third substrate 43, and an aluminum oxide ceramic as an insulating material. -Green sheet is formed into a box shape and then sintered. A plurality of mounting terminals 45 are formed on the outer bottom surface of the first substrate 41. The third substrate 43 is an annular body from which the central portion is removed, and a metal seal ring 44 such as Kovar is formed on the upper peripheral edge of the third substrate 43.
The third substrate 43 and the second substrate 42 form a recess (cavity) that accommodates the piezoelectric vibration element 1. A plurality of element mounting pads 47 that are electrically connected to the mounting terminals 45 by conductors 46 are provided at predetermined positions on the upper surface of the second substrate 42. The position of the element mounting pad 47 is arranged so as to correspond to the pad electrode 29a formed on the first support body 14a when the piezoelectric vibration element 1 is placed.

  When fixing the piezoelectric vibrator 5, first, the conductive adhesive 30 is applied to the pad electrode 29 a of the piezoelectric vibration element 1, and this is reversed (inverted) and placed on the element mounting pad 47 of the package body 40. Apply a load. As a characteristic of the conductive adhesive 30, the magnitude of stress (strain) caused by the adhesive 30 increases in the order of a silicone-based adhesive, an epoxy-based adhesive, and a polyimide-based adhesive. Further, degassing increases in the order of polyimide adhesive, epoxy adhesive, and silicone adhesive. As the conductive adhesive 30, it was decided to use a polyimide adhesive with little degassing in consideration of the secular change.

In order to cure the conductive adhesive 30 of the piezoelectric vibrator 1 mounted on the package body 40, it is placed in a high temperature furnace at a predetermined temperature for a predetermined time. After the conductive adhesive 30 is cured, the pad electrode 29b that is inverted to the surface side and the electrode terminal 48 of the package body 40 are electrically connected by the bonding wire BW. As shown in FIG. 15B, the piezoelectric vibration element 1 is supported / fixed to the package body 40 only at one place (one point), that is, the fixed part between the pad electrode 29a and the element mounting pad 47. For this reason, it is possible to reduce the magnitude of the stress generated by the support fixation.
After the annealing treatment, the frequency is adjusted by adding mass to the excitation electrodes 25a and 25b or reducing the mass. The lid member 49 is placed on the seal ring 44 formed on the upper surface of the package body 40, and the lid member 49 is sealed by seam welding in a vacuum or in an atmosphere of nitrogen N2 gas, whereby the piezoelectric vibrator 5 is completed. To do. Alternatively, there is also a method in which the lid member 49 is placed on the low melting point glass applied to the upper surface of the package body 40 and melted and adhered. Also in this case, the package cavity is evacuated or filled with an inert gas such as nitrogen N 2 gas to complete the piezoelectric vibrator 5.

  Each of the piezoelectric vibration elements 1, 2, and 3 shown in FIGS. 1, 6, and 7 is formed with pad electrodes 29 a and 29 b facing the upper and lower surfaces of the piezoelectric substrate 10. As shown in FIG. 15, when the piezoelectric vibration element 1 is accommodated in a package, the piezoelectric vibration element 1 is turned over, and the pad electrode 29a and the element mounting pad 47 of the package are fixed and connected with a conductive adhesive. The pad electrode 29b on the front surface side and the electrode terminal 48 of the package are connected by a bonding wire BW. Thus, when the site | part which supports the piezoelectric vibration element 1 becomes one point, the stress resulting from a conductive adhesive will become small. Further, when the piezoelectric vibrating element 1 is turned upside down and accommodated in a package, and the larger excitation electrode 25b is placed on the upper surface, fine tuning of the frequency of the piezoelectric vibrating element 1 is facilitated.

Alternatively, the piezoelectric vibrator 5 may be configured using piezoelectric vibration elements formed with the pad electrodes 29a and 29b spaced apart. In this case as well, a piezoelectric vibrator can be configured similarly to the piezoelectric vibrator 5 described with reference to FIG.
Further, as shown in FIG. 9, the piezoelectric vibrator 5 may be configured by using the piezoelectric vibration element 1 in which the pad electrodes 29a and 29b are formed on the same surface with a space therebetween. In this case, the piezoelectric vibration element is applied to the pad electrodes 29a and 29b by applying a conductive adhesive, placed on the element mounting pad formed on the package body 40 by being inverted, and supported and fixed by applying a load. It is the structure which aimed at. Although it is a structure suitable for a low profile, since the supported part has two points, the stress caused by the conductive adhesive may be slightly increased.
In the above-described embodiment of the piezoelectric vibrator 5, an example in which a laminated plate is used for the package body 40 has been described. However, a single-layer ceramic plate is used for the package body 40, and a cap that is drawn on the lid is used. A piezoelectric vibrator may be configured.

Since the piezoelectric vibrator shown in FIG. 15 is configured using the piezoelectric vibrators 1, 2, and 3 shown in the embodiments of FIGS. 1, 6, and 7, the high-frequency piezoelectric vibrator is downsized, Since the site for supporting the piezoelectric vibration elements 1, 2 and 3 is one point, and by providing a slit between the support portion and the vibration region, it is possible to reduce the stress caused by the conductive adhesive, There is an effect that a piezoelectric vibrator excellent in frequency reproducibility, frequency temperature characteristics, CI temperature characteristics, and frequency aging characteristics can be obtained.
1 and FIG. 3, the electrode materials of the excitation electrodes 25a and 25b are made different from the electrode materials of the lead electrodes 27a and 27b and the pad electrodes 29a and 29b. Since the piezoelectric vibration elements 1, 2, and 3 configured so that the film thickness is optimal for each function are used, the CI value of the main vibration is small, and the ratio of the CI value of the adjacent spurious to the CI value of the main vibration is That is, there is an effect that piezoelectric vibrators 1, 2, and 3 having a large CI value ratio can be obtained.

  FIG. 16 is a longitudinal sectional view showing an embodiment of the piezoelectric device 6 according to the present invention. The electronic device 6 includes the piezoelectric vibration element 1 of the present invention (which may be the piezoelectric vibration elements 2 and 3), thermistor Th that is one of electronic components and is a temperature sensor as a temperature sensor, the piezoelectric vibration element 1, And a package for housing the thermistor Th. The package includes a package main body 40 a and a lid member 49. The package body 40a has a cavity 31 for accommodating the piezoelectric vibration element 1 on the upper surface side, and a recess 32 for accommodating the thermistor Th on the outer lower surface side. An element mounting pad 47 is provided at an end of the inner bottom surface of the cavity 31, and the element mounting pad 47 is electrically connected to the mounting terminal 45 by an internal conductor 46. The conductive adhesive 30 is applied to the pad electrode 29 a of the piezoelectric vibration element 1, and this is reversed and placed on the element mounting pad 47. The pad electrode 29b that is reversed and becomes the surface side is connected to the electrode terminal 48 by a bonding wire BW. A seal ring 44 made of Kovar or the like is fired on the upper portion of the package main body 40a. A lid member 49 is placed on the seal ring 44 and welded using a resistance welding machine or the like to hermetically seal the cavity 31. To do. The cavity 31 may be evacuated or filled with an inert gas. The terminal of the thermistor Th is connected to the concave portion 32 on the back surface using a solder ball or the like to complete the electronic device 6.

In the above embodiment example, the concave portion 32 is formed on the outer lower surface side of the package body 40a and the electronic component is mounted. However, the concave portion 32 is formed on the inner bottom surface of the package body 40a and the electronic component is mounted. May be.
Moreover, although the example which accommodated the piezoelectric vibration element 2 and the thermistor Th in the package 40a was demonstrated, as an electronic component accommodated in the package 40a, at least one of a thermistor, a capacitor | condenser, a reactance element, and a semiconductor element is accommodated. It is desirable to construct an electronic device.

When the electronic device 6 in which the piezoelectric vibration element 1 and the thermistor Th are accommodated in the package 40a is configured as in the embodiment shown in FIG. 16, the thermistor Th as a temperature-sensitive element is arranged very close to the piezoelectric vibration element 1. Therefore, there is an effect that a temperature change of the piezoelectric vibration element 1 can be sensed quickly. Moreover, since an electronic device is comprised with the piezoelectric vibration element of this invention and said electronic component, since a high frequency and a small electronic device can be comprised, there exists an effect that it can utilize for various uses.
In addition, when an electronic device (piezoelectric device) is configured using any one of a variable capacitance element, thermistor, inductor, and capacitor as an electronic component, an electronic device suitable for the required specifications can be realized in a small size and at low cost. effective.

FIG. 17 is a view showing a configuration of a piezoelectric oscillator 7 which is a kind of electronic device according to an embodiment of the present invention, where FIG. 17 (a) is a longitudinal sectional view and FIG. 17 (b) is a lid member. FIG. The piezoelectric oscillator 7 includes a package main body 40b, a lid member 49, the piezoelectric vibration element 1, an IC component 51 on which an oscillation circuit for exciting the piezoelectric vibration element 1 is mounted, a variable capacitance element whose capacitance changes with voltage, and temperature. And at least one of electronic components 52 such as a thermistor and an inductor whose resistance changes.
A conductive adhesive (polyimide) 30 is applied to the pad electrode 29 a of the piezoelectric vibration element 1, and this is reversed and placed on the element mounting pad 47 of the package body 40 b, and the pad electrode 29 a and the element mounting pad 47 are connected. Ensuring continuity. The pad electrode 29b that is turned upside down and is connected to the other electrode terminal 48 of the package main body 40b by a bonding wire, and electrical connection with one electrode terminal 55 of the IC component 51 is achieved. The IC component 51 is fixed at a predetermined position on the package body 40b, and the terminal of the IC component 51 and the electrode terminal 55 of the package body 40b are connected by the bonding wire BW. Further, the electronic component 52 is placed at a predetermined position of the package body 40b and connected using metal bumps or the like. The package body 40b is filled with an inert gas such as vacuum or nitrogen, and the package body 40b is sealed with a lid member 49 to complete the electronic device (piezoelectric oscillator) 7.
In the method of connecting the pad electrode 29b and the electrode terminal 48 of the package with the bonding wire BW, the portion supporting the piezoelectric vibration element 1 becomes one point, and the stress caused by the conductive adhesive is reduced. Further, since the piezoelectric vibrating element 1 is inverted and the larger excitation electrode 25b is placed on the upper surface when housed in the package, fine tuning of the frequency of the electronic device (piezoelectric oscillator) 7 is facilitated.

In the electronic device (piezoelectric oscillator) 7 shown in the embodiment of FIG. 17, the piezoelectric vibration element 1, the IC component 51, and the electronic component are arranged on the same piezoelectric substrate, but the electronic device (piezoelectric) of the embodiment shown in FIG. The oscillator 7 uses an H-type package main body 60, and the piezoelectric vibration element 1 is accommodated in a cavity 31 formed in the upper part, and the inside of the cavity is filled with vacuum or nitrogen N 2 gas and sealed with a lid member 61. In the lower part, an IC component 51 on which an oscillation circuit, an amplification circuit, etc. for exciting the piezoelectric vibration element 1 are mounted, a variable capacitance element, and an electronic component 52 such as an inductor, thermistor, capacitor, etc., as needed, are provided with metal bumps (Au Conductive and connected to the terminal 67 of the package body 60 via the bumps 68.
The electronic device (piezoelectric oscillator) 7 according to the present invention separates the piezoelectric vibration element 1 from the IC component 51 and the electronic component 52 and hermetically seals the piezoelectric vibration element 1 alone. Excellent frequency aging characteristics.

As shown in FIGS. 17 and 18, by configuring a piezoelectric device (for example, a voltage-controlled piezoelectric oscillator), the frequency reproducibility, frequency temperature characteristics, and aging characteristics are excellent, and the voltage is small and has a high frequency (for example, 490 MHz band). There is an effect that a control type piezoelectric oscillator can be obtained. Further, since the piezoelectric device uses the piezoelectric vibration element 1 of the fundamental wave, the capacitance ratio is small and the frequency variable width is widened. Furthermore, there is an effect that a voltage controlled piezoelectric oscillator having a good S / N ratio can be obtained.
In addition, a piezoelectric oscillator, a temperature compensated piezoelectric oscillator, or the like can be configured as the piezoelectric device, and there is an effect that a piezoelectric oscillator excellent in frequency reproducibility, aging characteristics, and frequency temperature characteristics can be configured.

FIG. 19 is a schematic configuration diagram showing a configuration of an electronic apparatus according to the present invention. The electronic device 8 includes the piezoelectric vibrator 5 described above. Examples of the electronic device 8 using the piezoelectric vibrator 5 include a transmission device. In these electronic devices 8, the piezoelectric vibrator 5 is used as a reference signal source, a voltage variable piezoelectric oscillator (VCXO), or the like, and can provide a small-sized electronic device having good characteristics.
As shown in the schematic diagram of FIG. 19, by using the piezoelectric vibrator of the present invention for an electronic device, an electronic device having a reference frequency source having a high frequency and excellent frequency stability and a good S / N ratio can be configured. There is an effect.

[Modified Embodiment]
As a technique for further reducing and suppressing the stress caused by mounting the piezoelectric vibration element, the following structure can be adopted.
The piezoelectric substrate 10 in the embodiment of FIG. 20A is a piezoelectric substrate 10 provided with a thin part having a vibration region 12 and a thick part provided at the periphery of the thin part and thicker than the thin part. In the piezoelectric substrate, the mount portion F is connected to the thick support portion 13 side by side through the buffer portion S in the direction of the edge, and the buffer portion S is interposed between the mount portion and the thick support portion. It has a slit 20, and the mount part F has chamfered parts 21 at both ends in a direction orthogonal to the direction in which the mount part F, the buffer part S, and the thick support part 13 are arranged. To do.
The piezoelectric substrate 10 of FIG. 20B is a piezoelectric substrate 10 including a thin portion having a vibration region 12 and a thick support portion 13 provided at the periphery of the thin portion and thicker than the thin portion. Mount portions F are connected to the meat support portion 13 side by side through the buffer portion S, and the buffer portion S has a slit 20 between the mount portion F and the thick wall support portion 13. The mounting portion F, the buffer portion S, and the thick support portion 13 have notch portions 22 at both ends in the direction orthogonal to the direction in which the mounting portion F, the buffer portion S, and the thick support portion 13 are arranged, and the longitudinal direction of the slit 20 is parallel to the orthogonal direction. The width in the orthogonal direction is narrower than the width in the longitudinal direction of the slit, and both end portions in the longitudinal direction of the slit are closer to the outer periphery in the orthogonal direction of the buffer portion S than both end portions of the mount portion F.
The piezoelectric substrate 10 in FIG. 20C is a piezoelectric substrate 10 including a thin portion having a vibration region 12 and a thick support portion 13 provided on the periphery of the thin portion. The buffer portion S and the mount portion F are sequentially connected, and the buffer portion S has a slit 20 between the mount portion F and the thick wall support portion 13, and the mount portion F includes the mount portion F and the buffer portion S. And the thick-walled support portion 13 are characterized by having cutout portions 22 at both ends in a direction perpendicular to the direction in which the thick support portions 13 are arranged.

FIG. 21 is characterized in that it takes the form of two-point support, that is, the mount portion F1 and the mount portion F2, with respect to the structure of FIG.
In FIGS. 20 and 21, inclined portions are illustrated on the inner walls of the support portions 14 and 15 of the thick support portion 13, while the outer side wall surface of the thick support portion 13 is illustrated in FIG. 14. Although the inclined surfaces as shown in FIG. 1 are not shown, these inclined portions and inclined surfaces are formed at corresponding portions as shown in FIG.
In addition, each code | symbol in FIG. 20, FIG. 21 respond | corresponds with the site | part which the same code | symbol of said each embodiment shows.

[Modified Example 2]
22A is a plan view of the piezoelectric vibration element 2, and FIG. 22B is an enlarged plan view of an embodiment of the pad electrode 29a (mount portion F) of the piezoelectric vibration element 1. FIG. FIG. 3C shows a cross-sectional view of the mount portion F. In this mount part F, the area is gained by making it uneven in order to improve the adhesive strength.

1, 2, 3 ... Piezoelectric vibration element 5, Piezoelectric vibrator 6, 7... Piezoelectric device, 8 ... Electronic device 10 ... Piezoelectric substrate 10 W ... Quartz wafer, 11 ... Recessed part 12 ... Vibration region 12b ... one side of the vibration region, 13 ... support part, 14 ... first support part, 14a ... first support part body, 14b ... first slope part, 14bb ... extremely slant part, 15 ... second support Part, 15a ... second support part main body, 15b ... second inclined part, 20 ... slit, 20a ... first slit, 20b ... second slit, 21 ... chamfered part, 22 ... notch part, 25a, 25b: Excitation electrode, 27a, 27b, 27c, 27d, 27g ... Lead electrode, 29a, 29b, 29c, 29g ... Pad electrode, 30 ... Conductive adhesive, 31 ... Cavity, 32 ... Recess, 33 ... For mounting electronic components Pad, 40, 40a, 40 DESCRIPTION OF SYMBOLS ... Package body, 41 ... First substrate, 42 ... Second substrate, 43 ... Third substrate, 44 ... Seal ring, 45 ... Mounting terminal, 46 ... Conductor, 47 ... Element mounting pad, 48 ... Electrode terminal, 49 ... lid member, 51 ... IC component, 52 electronic component, 55 ... electrode terminal, 60 ... package body, 61 ... lid member, 65 ... mounting terminal, 66 ... conductor, 67 ... component terminal, 68 ... metal bump (Au bump) ), Th ... Thermistor, F, F1, F2 ... Mount part, S ... Buffer part

Claims (10)

The crystal axis of quartz, the electrical axis is the X axis, the mechanical axis is the Y axis, the optical axis is the Z axis, and the X axis is the rotation axis so that the Z axis rotates in the −Y direction of the Y axis on the + Z side. The axis tilted in the direction of Z is the Z ′ axis, the Y axis is the axis tilted so that the + Y side rotates in the + Z direction of the Z axis, the Y ′ axis, and the plane including the X axis and the Z ′ axis is the principal surface and then, the Y'thickness direction along the axis Satoshi, a quartz substrate including a first region, and the second region the thickness is thicker than the first region including a vibration region,
A first excitation electrode provided in the first region on one main surface side of the quartz substrate;
A second excitation electrode provided in the first region on the other main surface side of the quartz substrate;
With
The first region is
A first outer edge and a second outer edge along the Z′- axis direction; and a third outer edge and a fourth outer edge along the X-axis direction;
The second region is
The first thick part main body provided along the first outer edge, and the first thick part from the first outer edge provided between the first outer edge and the first thick part main body. A first thick part having a first inclined part whose thickness increases toward the part body;
The second thick part main body provided along the third outer edge, and the second thick part from the third outer edge provided between the third outer edge and the second thick part main body. A second thick part having a second inclined part that increases in thickness toward the part main body,
The first thick portion is provided on the one main surface side and connected to the first excitation electrode, and on the other main surface side, and is provided on the other main surface side in the plan view. A second pad electrode overlapping the first pad electrode and connected to the second excitation electrode;
The first excitation electrode includes a fifth outer edge and a sixth outer edge along the X-axis direction ,
Flat surface view, the fifth edge of the imaginary straight line along the street the X-axis direction of the first imaginary line, the sixth imaginary straight line along the street the X-axis direction outer second virtual lines, the When a virtual straight line passing through the center in the Z′-axis direction of the first excitation electrode and along the X-axis direction is defined as a third virtual line,
Wherein at least a portion of the first pad electrode in plan view, a between the front Symbol the second virtual line and the first imaginary line, a position closer to the first virtual line than the third imaginary line are arranged to,
The vibration element , wherein a center of the first pad electrode in the Z′-axis direction is disposed closer to the first imaginary line than the third imaginary line . In claim 1,
One main surface of the first thick part protrudes from one main surface of the first region,
The other main surface of the first thick part and the other main surface of the first region are the same surface,
One main surface of the second thick part is protruded from one main surface of the first region,
The vibration element, wherein the other main surface of the second thick part and the other main surface of the first region are the same surface. In claim 2 ,
The one main surface of the first thick portion and the one main surface of the second thick portion protrude from the one main surface of the first region in the + Y direction of the Y ′ axis. A vibrating element characterized by being provided. In any one of Claims 1 thru | or 3 ,
The vibrating element according to claim 2, wherein the second thick portion is in the + Z 'direction of the Z' axis. In any one of Claims 1 thru | or 4 ,
The first thick portion is in the + X direction of the X axis. The vibration element according to any one of claims 1 to 5 ,
A package containing the vibration element;
A vibrator characterized by comprising: The vibration element according to any one of claims 1 to 5 ,
Electronic components,
An electronic device comprising: In claim 7 ,
The electronic component is
An electronic device characterized by being one of a variable capacitance element, a thermistor, an inductor, and a capacitor. In claim 7 or 8 ,
An electronic device comprising an oscillation circuit for exciting the vibration element in a package. An electronic apparatus comprising the vibrator according to claim 6 .

Images